1	// SPDX-License-Identifier: GPL-2.0
2	/*
3	* Copyright (C) 2007 Oracle. All rights reserved.
4	*/
5
6	#include <linux/sched.h>
7	#include <linux/sched/signal.h>
8	#include <linux/pagemap.h>
9	#include <linux/writeback.h>
10	#include <linux/blkdev.h>
11	#include <linux/sort.h>
12	#include <linux/rcupdate.h>
13	#include <linux/kthread.h>
14	#include <linux/slab.h>
15	#include <linux/ratelimit.h>
16	#include <linux/percpu_counter.h>
17	#include <linux/lockdep.h>
18	#include <linux/crc32c.h>
19	#include "ctree.h"
20	#include "extent-tree.h"
21	#include "transaction.h"
22	#include "disk-io.h"
23	#include "print-tree.h"
24	#include "volumes.h"
25	#include "raid56.h"
26	#include "locking.h"
27	#include "free-space-cache.h"
28	#include "free-space-tree.h"
29	#include "qgroup.h"
30	#include "ref-verify.h"
31	#include "space-info.h"
32	#include "block-rsv.h"
33	#include "discard.h"
34	#include "zoned.h"
35	#include "dev-replace.h"
36	#include "fs.h"
37	#include "accessors.h"
38	#include "root-tree.h"
39	#include "file-item.h"
40	#include "orphan.h"
41	#include "tree-checker.h"
42	#include "raid-stripe-tree.h"
43
44	#undef SCRAMBLE_DELAYED_REFS
45
46
47	static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
48	struct btrfs_delayed_ref_head *href,
49	struct btrfs_delayed_ref_node *node, u64 parent,
50	u64 root_objectid, u64 owner_objectid,
51	u64 owner_offset,
52	struct btrfs_delayed_extent_op *extra_op);
53	static void __run_delayed_extent_op(struct btrfs_delayed_extent_op *extent_op,
54	struct extent_buffer *leaf,
55	struct btrfs_extent_item *ei);
56	static int alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
57	u64 parent, u64 root_objectid,
58	u64 flags, u64 owner, u64 offset,
59	struct btrfs_key *ins, int ref_mod, u64 oref_root);
60	static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
61	struct btrfs_delayed_ref_node *node,
62	struct btrfs_delayed_extent_op *extent_op);
63	static int find_next_key(struct btrfs_path *path, int level,
64	struct btrfs_key *key);
65
66	static int block_group_bits(struct btrfs_block_group *cache, u64 bits)
67	{
68	return (cache->flags & bits) == bits;
69	}
70
71	/* simple helper to search for an existing data extent at a given offset */
72	int btrfs_lookup_data_extent(struct btrfs_fs_info *fs_info, u64 start, u64 len)
73	{
74	struct btrfs_root *root = btrfs_extent_root(fs_info, bytenr: start);
75	int ret;
76	struct btrfs_key key;
77	struct btrfs_path *path;
78
79	path = btrfs_alloc_path();
80	if (!path)
81	return -ENOMEM;
82
83	key.objectid = start;
84	key.offset = len;
85	key.type = BTRFS_EXTENT_ITEM_KEY;
86	ret = btrfs_search_slot(NULL, root, key: &key, p: path, ins_len: 0, cow: 0);
87	btrfs_free_path(p: path);
88	return ret;
89	}
90
91	/*
92	* helper function to lookup reference count and flags of a tree block.
93	*
94	* the head node for delayed ref is used to store the sum of all the
95	* reference count modifications queued up in the rbtree. the head
96	* node may also store the extent flags to set. This way you can check
97	* to see what the reference count and extent flags would be if all of
98	* the delayed refs are not processed.
99	*/
100	int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,
101	struct btrfs_fs_info *fs_info, u64 bytenr,
102	u64 offset, int metadata, u64 *refs, u64 *flags,
103	u64 *owning_root)
104	{
105	struct btrfs_root *extent_root;
106	struct btrfs_delayed_ref_head *head;
107	struct btrfs_delayed_ref_root *delayed_refs;
108	struct btrfs_path *path;
109	struct btrfs_extent_item *ei;
110	struct extent_buffer *leaf;
111	struct btrfs_key key;
112	u32 item_size;
113	u64 num_refs;
114	u64 extent_flags;
115	u64 owner = 0;
116	int ret;
117
118	/*
119	* If we don't have skinny metadata, don't bother doing anything
120	* different
121	*/
122	if (metadata && !btrfs_fs_incompat(fs_info, SKINNY_METADATA)) {
123	offset = fs_info->nodesize;
124	metadata = 0;
125	}
126
127	path = btrfs_alloc_path();
128	if (!path)
129	return -ENOMEM;
130
131	if (!trans) {
132	path->skip_locking = 1;
133	path->search_commit_root = 1;
134	}
135
136	search_again:
137	key.objectid = bytenr;
138	key.offset = offset;
139	if (metadata)
140	key.type = BTRFS_METADATA_ITEM_KEY;
141	else
142	key.type = BTRFS_EXTENT_ITEM_KEY;
143
144	extent_root = btrfs_extent_root(fs_info, bytenr);
145	ret = btrfs_search_slot(NULL, root: extent_root, key: &key, p: path, ins_len: 0, cow: 0);
146	if (ret < 0)
147	goto out_free;
148
149	if (ret > 0 && metadata && key.type == BTRFS_METADATA_ITEM_KEY) {
150	if (path->slots[0]) {
151	path->slots[0]--;
152	btrfs_item_key_to_cpu(eb: path->nodes[0], cpu_key: &key,
153	nr: path->slots[0]);
154	if (key.objectid == bytenr &&
155	key.type == BTRFS_EXTENT_ITEM_KEY &&
156	key.offset == fs_info->nodesize)
157	ret = 0;
158	}
159	}
160
161	if (ret == 0) {
162	leaf = path->nodes[0];
163	item_size = btrfs_item_size(eb: leaf, slot: path->slots[0]);
164	if (item_size >= sizeof(*ei)) {
165	ei = btrfs_item_ptr(leaf, path->slots[0],
166	struct btrfs_extent_item);
167	num_refs = btrfs_extent_refs(eb: leaf, s: ei);
168	extent_flags = btrfs_extent_flags(eb: leaf, s: ei);
169	owner = btrfs_get_extent_owner_root(fs_info, leaf,
170	slot: path->slots[0]);
171	} else {
172	ret = -EUCLEAN;
173	btrfs_err(fs_info,
174	"unexpected extent item size, has %u expect >= %zu",
175	item_size, sizeof(*ei));
176	if (trans)
177	btrfs_abort_transaction(trans, ret);
178	else
179	btrfs_handle_fs_error(fs_info, ret, NULL);
180
181	goto out_free;
182	}
183
184	BUG_ON(num_refs == 0);
185	} else {
186	num_refs = 0;
187	extent_flags = 0;
188	ret = 0;
189	}
190
191	if (!trans)
192	goto out;
193
194	delayed_refs = &trans->transaction->delayed_refs;
195	spin_lock(lock: &delayed_refs->lock);
196	head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
197	if (head) {
198	if (!mutex_trylock(lock: &head->mutex)) {
199	refcount_inc(r: &head->refs);
200	spin_unlock(lock: &delayed_refs->lock);
201
202	btrfs_release_path(p: path);
203
204	/*
205	* Mutex was contended, block until it's released and try
206	* again
207	*/
208	mutex_lock(&head->mutex);
209	mutex_unlock(lock: &head->mutex);
210	btrfs_put_delayed_ref_head(head);
211	goto search_again;
212	}
213	spin_lock(lock: &head->lock);
214	if (head->extent_op && head->extent_op->update_flags)
215	extent_flags |= head->extent_op->flags_to_set;
216	else
217	BUG_ON(num_refs == 0);
218
219	num_refs += head->ref_mod;
220	spin_unlock(lock: &head->lock);
221	mutex_unlock(lock: &head->mutex);
222	}
223	spin_unlock(lock: &delayed_refs->lock);
224	out:
225	WARN_ON(num_refs == 0);
226	if (refs)
227	*refs = num_refs;
228	if (flags)
229	*flags = extent_flags;
230	if (owning_root)
231	*owning_root = owner;
232	out_free:
233	btrfs_free_path(p: path);
234	return ret;
235	}
236
237	/*
238	* Back reference rules. Back refs have three main goals:
239	*
240	* 1) differentiate between all holders of references to an extent so that
241	* when a reference is dropped we can make sure it was a valid reference
242	* before freeing the extent.
243	*
244	* 2) Provide enough information to quickly find the holders of an extent
245	* if we notice a given block is corrupted or bad.
246	*
247	* 3) Make it easy to migrate blocks for FS shrinking or storage pool
248	* maintenance. This is actually the same as #2, but with a slightly
249	* different use case.
250	*
251	* There are two kinds of back refs. The implicit back refs is optimized
252	* for pointers in non-shared tree blocks. For a given pointer in a block,
253	* back refs of this kind provide information about the block's owner tree
254	* and the pointer's key. These information allow us to find the block by
255	* b-tree searching. The full back refs is for pointers in tree blocks not
256	* referenced by their owner trees. The location of tree block is recorded
257	* in the back refs. Actually the full back refs is generic, and can be
258	* used in all cases the implicit back refs is used. The major shortcoming
259	* of the full back refs is its overhead. Every time a tree block gets
260	* COWed, we have to update back refs entry for all pointers in it.
261	*
262	* For a newly allocated tree block, we use implicit back refs for
263	* pointers in it. This means most tree related operations only involve
264	* implicit back refs. For a tree block created in old transaction, the
265	* only way to drop a reference to it is COW it. So we can detect the
266	* event that tree block loses its owner tree's reference and do the
267	* back refs conversion.
268	*
269	* When a tree block is COWed through a tree, there are four cases:
270	*
271	* The reference count of the block is one and the tree is the block's
272	* owner tree. Nothing to do in this case.
273	*
274	* The reference count of the block is one and the tree is not the
275	* block's owner tree. In this case, full back refs is used for pointers
276	* in the block. Remove these full back refs, add implicit back refs for
277	* every pointers in the new block.
278	*
279	* The reference count of the block is greater than one and the tree is
280	* the block's owner tree. In this case, implicit back refs is used for
281	* pointers in the block. Add full back refs for every pointers in the
282	* block, increase lower level extents' reference counts. The original
283	* implicit back refs are entailed to the new block.
284	*
285	* The reference count of the block is greater than one and the tree is
286	* not the block's owner tree. Add implicit back refs for every pointer in
287	* the new block, increase lower level extents' reference count.
288	*
289	* Back Reference Key composing:
290	*
291	* The key objectid corresponds to the first byte in the extent,
292	* The key type is used to differentiate between types of back refs.
293	* There are different meanings of the key offset for different types
294	* of back refs.
295	*
296	* File extents can be referenced by:
297	*
298	* - multiple snapshots, subvolumes, or different generations in one subvol
299	* - different files inside a single subvolume
300	* - different offsets inside a file (bookend extents in file.c)
301	*
302	* The extent ref structure for the implicit back refs has fields for:
303	*
304	* - Objectid of the subvolume root
305	* - objectid of the file holding the reference
306	* - original offset in the file
307	* - how many bookend extents
308	*
309	* The key offset for the implicit back refs is hash of the first
310	* three fields.
311	*
312	* The extent ref structure for the full back refs has field for:
313	*
314	* - number of pointers in the tree leaf
315	*
316	* The key offset for the implicit back refs is the first byte of
317	* the tree leaf
318	*
319	* When a file extent is allocated, The implicit back refs is used.
320	* the fields are filled in:
321	*
322	* (root_key.objectid, inode objectid, offset in file, 1)
323	*
324	* When a file extent is removed file truncation, we find the
325	* corresponding implicit back refs and check the following fields:
326	*
327	* (btrfs_header_owner(leaf), inode objectid, offset in file)
328	*
329	* Btree extents can be referenced by:
330	*
331	* - Different subvolumes
332	*
333	* Both the implicit back refs and the full back refs for tree blocks
334	* only consist of key. The key offset for the implicit back refs is
335	* objectid of block's owner tree. The key offset for the full back refs
336	* is the first byte of parent block.
337	*
338	* When implicit back refs is used, information about the lowest key and
339	* level of the tree block are required. These information are stored in
340	* tree block info structure.
341	*/
342
343	/*
344	* is_data == BTRFS_REF_TYPE_BLOCK, tree block type is required,
345	* is_data == BTRFS_REF_TYPE_DATA, data type is requiried,
346	* is_data == BTRFS_REF_TYPE_ANY, either type is OK.
347	*/
348	int btrfs_get_extent_inline_ref_type(const struct extent_buffer *eb,
349	struct btrfs_extent_inline_ref *iref,
350	enum btrfs_inline_ref_type is_data)
351	{
352	struct btrfs_fs_info *fs_info = eb->fs_info;
353	int type = btrfs_extent_inline_ref_type(eb, s: iref);
354	u64 offset = btrfs_extent_inline_ref_offset(eb, s: iref);
355
356	if (type == BTRFS_EXTENT_OWNER_REF_KEY) {
357	ASSERT(btrfs_fs_incompat(fs_info, SIMPLE_QUOTA));
358	return type;
359	}
360
361	if (type == BTRFS_TREE_BLOCK_REF_KEY ||
362	type == BTRFS_SHARED_BLOCK_REF_KEY ||
363	type == BTRFS_SHARED_DATA_REF_KEY ||
364	type == BTRFS_EXTENT_DATA_REF_KEY) {
365	if (is_data == BTRFS_REF_TYPE_BLOCK) {
366	if (type == BTRFS_TREE_BLOCK_REF_KEY)
367	return type;
368	if (type == BTRFS_SHARED_BLOCK_REF_KEY) {
369	ASSERT(fs_info);
370	/*
371	* Every shared one has parent tree block,
372	* which must be aligned to sector size.
373	*/
374	if (offset && IS_ALIGNED(offset, fs_info->sectorsize))
375	return type;
376	}
377	} else if (is_data == BTRFS_REF_TYPE_DATA) {
378	if (type == BTRFS_EXTENT_DATA_REF_KEY)
379	return type;
380	if (type == BTRFS_SHARED_DATA_REF_KEY) {
381	ASSERT(fs_info);
382	/*
383	* Every shared one has parent tree block,
384	* which must be aligned to sector size.
385	*/
386	if (offset &&
387	IS_ALIGNED(offset, fs_info->sectorsize))
388	return type;
389	}
390	} else {
391	ASSERT(is_data == BTRFS_REF_TYPE_ANY);
392	return type;
393	}
394	}
395
396	WARN_ON(1);
397	btrfs_print_leaf(l: eb);
398	btrfs_err(fs_info,
399	"eb %llu iref 0x%lx invalid extent inline ref type %d",
400	eb->start, (unsigned long)iref, type);
401
402	return BTRFS_REF_TYPE_INVALID;
403	}
404
405	u64 hash_extent_data_ref(u64 root_objectid, u64 owner, u64 offset)
406	{
407	u32 high_crc = ~(u32)0;
408	u32 low_crc = ~(u32)0;
409	__le64 lenum;
410
411	lenum = cpu_to_le64(root_objectid);
412	high_crc = crc32c(crc: high_crc, address: &lenum, length: sizeof(lenum));
413	lenum = cpu_to_le64(owner);
414	low_crc = crc32c(crc: low_crc, address: &lenum, length: sizeof(lenum));
415	lenum = cpu_to_le64(offset);
416	low_crc = crc32c(crc: low_crc, address: &lenum, length: sizeof(lenum));
417
418	return ((u64)high_crc << 31) ^ (u64)low_crc;
419	}
420
421	static u64 hash_extent_data_ref_item(struct extent_buffer *leaf,
422	struct btrfs_extent_data_ref *ref)
423	{
424	return hash_extent_data_ref(root_objectid: btrfs_extent_data_ref_root(eb: leaf, s: ref),
425	owner: btrfs_extent_data_ref_objectid(eb: leaf, s: ref),
426	offset: btrfs_extent_data_ref_offset(eb: leaf, s: ref));
427	}
428
429	static int match_extent_data_ref(struct extent_buffer *leaf,
430	struct btrfs_extent_data_ref *ref,
431	u64 root_objectid, u64 owner, u64 offset)
432	{
433	if (btrfs_extent_data_ref_root(eb: leaf, s: ref) != root_objectid ||
434	btrfs_extent_data_ref_objectid(eb: leaf, s: ref) != owner ||
435	btrfs_extent_data_ref_offset(eb: leaf, s: ref) != offset)
436	return 0;
437	return 1;
438	}
439
440	static noinline int lookup_extent_data_ref(struct btrfs_trans_handle *trans,
441	struct btrfs_path *path,
442	u64 bytenr, u64 parent,
443	u64 root_objectid,
444	u64 owner, u64 offset)
445	{
446	struct btrfs_root *root = btrfs_extent_root(fs_info: trans->fs_info, bytenr);
447	struct btrfs_key key;
448	struct btrfs_extent_data_ref *ref;
449	struct extent_buffer *leaf;
450	u32 nritems;
451	int ret;
452	int recow;
453	int err = -ENOENT;
454
455	key.objectid = bytenr;
456	if (parent) {
457	key.type = BTRFS_SHARED_DATA_REF_KEY;
458	key.offset = parent;
459	} else {
460	key.type = BTRFS_EXTENT_DATA_REF_KEY;
461	key.offset = hash_extent_data_ref(root_objectid,
462	owner, offset);
463	}
464	again:
465	recow = 0;
466	ret = btrfs_search_slot(trans, root, key: &key, p: path, ins_len: -1, cow: 1);
467	if (ret < 0) {
468	err = ret;
469	goto fail;
470	}
471
472	if (parent) {
473	if (!ret)
474	return 0;
475	goto fail;
476	}
477
478	leaf = path->nodes[0];
479	nritems = btrfs_header_nritems(eb: leaf);
480	while (1) {
481	if (path->slots[0] >= nritems) {
482	ret = btrfs_next_leaf(root, path);
483	if (ret < 0)
484	err = ret;
485	if (ret)
486	goto fail;
487
488	leaf = path->nodes[0];
489	nritems = btrfs_header_nritems(eb: leaf);
490	recow = 1;
491	}
492
493	btrfs_item_key_to_cpu(eb: leaf, cpu_key: &key, nr: path->slots[0]);
494	if (key.objectid != bytenr ||
495	key.type != BTRFS_EXTENT_DATA_REF_KEY)
496	goto fail;
497
498	ref = btrfs_item_ptr(leaf, path->slots[0],
499	struct btrfs_extent_data_ref);
500
501	if (match_extent_data_ref(leaf, ref, root_objectid,
502	owner, offset)) {
503	if (recow) {
504	btrfs_release_path(p: path);
505	goto again;
506	}
507	err = 0;
508	break;
509	}
510	path->slots[0]++;
511	}
512	fail:
513	return err;
514	}
515
516	static noinline int insert_extent_data_ref(struct btrfs_trans_handle *trans,
517	struct btrfs_path *path,
518	u64 bytenr, u64 parent,
519	u64 root_objectid, u64 owner,
520	u64 offset, int refs_to_add)
521	{
522	struct btrfs_root *root = btrfs_extent_root(fs_info: trans->fs_info, bytenr);
523	struct btrfs_key key;
524	struct extent_buffer *leaf;
525	u32 size;
526	u32 num_refs;
527	int ret;
528
529	key.objectid = bytenr;
530	if (parent) {
531	key.type = BTRFS_SHARED_DATA_REF_KEY;
532	key.offset = parent;
533	size = sizeof(struct btrfs_shared_data_ref);
534	} else {
535	key.type = BTRFS_EXTENT_DATA_REF_KEY;
536	key.offset = hash_extent_data_ref(root_objectid,
537	owner, offset);
538	size = sizeof(struct btrfs_extent_data_ref);
539	}
540
541	ret = btrfs_insert_empty_item(trans, root, path, key: &key, data_size: size);
542	if (ret && ret != -EEXIST)
543	goto fail;
544
545	leaf = path->nodes[0];
546	if (parent) {
547	struct btrfs_shared_data_ref *ref;
548	ref = btrfs_item_ptr(leaf, path->slots[0],
549	struct btrfs_shared_data_ref);
550	if (ret == 0) {
551	btrfs_set_shared_data_ref_count(eb: leaf, s: ref, val: refs_to_add);
552	} else {
553	num_refs = btrfs_shared_data_ref_count(eb: leaf, s: ref);
554	num_refs += refs_to_add;
555	btrfs_set_shared_data_ref_count(eb: leaf, s: ref, val: num_refs);
556	}
557	} else {
558	struct btrfs_extent_data_ref *ref;
559	while (ret == -EEXIST) {
560	ref = btrfs_item_ptr(leaf, path->slots[0],
561	struct btrfs_extent_data_ref);
562	if (match_extent_data_ref(leaf, ref, root_objectid,
563	owner, offset))
564	break;
565	btrfs_release_path(p: path);
566	key.offset++;
567	ret = btrfs_insert_empty_item(trans, root, path, key: &key,
568	data_size: size);
569	if (ret && ret != -EEXIST)
570	goto fail;
571
572	leaf = path->nodes[0];
573	}
574	ref = btrfs_item_ptr(leaf, path->slots[0],
575	struct btrfs_extent_data_ref);
576	if (ret == 0) {
577	btrfs_set_extent_data_ref_root(eb: leaf, s: ref,
578	val: root_objectid);
579	btrfs_set_extent_data_ref_objectid(eb: leaf, s: ref, val: owner);
580	btrfs_set_extent_data_ref_offset(eb: leaf, s: ref, val: offset);
581	btrfs_set_extent_data_ref_count(eb: leaf, s: ref, val: refs_to_add);
582	} else {
583	num_refs = btrfs_extent_data_ref_count(eb: leaf, s: ref);
584	num_refs += refs_to_add;
585	btrfs_set_extent_data_ref_count(eb: leaf, s: ref, val: num_refs);
586	}
587	}
588	btrfs_mark_buffer_dirty(trans, buf: leaf);
589	ret = 0;
590	fail:
591	btrfs_release_path(p: path);
592	return ret;
593	}
594
595	static noinline int remove_extent_data_ref(struct btrfs_trans_handle *trans,
596	struct btrfs_root *root,
597	struct btrfs_path *path,
598	int refs_to_drop)
599	{
600	struct btrfs_key key;
601	struct btrfs_extent_data_ref *ref1 = NULL;
602	struct btrfs_shared_data_ref *ref2 = NULL;
603	struct extent_buffer *leaf;
604	u32 num_refs = 0;
605	int ret = 0;
606
607	leaf = path->nodes[0];
608	btrfs_item_key_to_cpu(eb: leaf, cpu_key: &key, nr: path->slots[0]);
609
610	if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
611	ref1 = btrfs_item_ptr(leaf, path->slots[0],
612	struct btrfs_extent_data_ref);
613	num_refs = btrfs_extent_data_ref_count(eb: leaf, s: ref1);
614	} else if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
615	ref2 = btrfs_item_ptr(leaf, path->slots[0],
616	struct btrfs_shared_data_ref);
617	num_refs = btrfs_shared_data_ref_count(eb: leaf, s: ref2);
618	} else {
619	btrfs_err(trans->fs_info,
620	"unrecognized backref key (%llu %u %llu)",
621	key.objectid, key.type, key.offset);
622	btrfs_abort_transaction(trans, -EUCLEAN);
623	return -EUCLEAN;
624	}
625
626	BUG_ON(num_refs < refs_to_drop);
627	num_refs -= refs_to_drop;
628
629	if (num_refs == 0) {
630	ret = btrfs_del_item(trans, root, path);
631	} else {
632	if (key.type == BTRFS_EXTENT_DATA_REF_KEY)
633	btrfs_set_extent_data_ref_count(eb: leaf, s: ref1, val: num_refs);
634	else if (key.type == BTRFS_SHARED_DATA_REF_KEY)
635	btrfs_set_shared_data_ref_count(eb: leaf, s: ref2, val: num_refs);
636	btrfs_mark_buffer_dirty(trans, buf: leaf);
637	}
638	return ret;
639	}
640
641	static noinline u32 extent_data_ref_count(struct btrfs_path *path,
642	struct btrfs_extent_inline_ref *iref)
643	{
644	struct btrfs_key key;
645	struct extent_buffer *leaf;
646	struct btrfs_extent_data_ref *ref1;
647	struct btrfs_shared_data_ref *ref2;
648	u32 num_refs = 0;
649	int type;
650
651	leaf = path->nodes[0];
652	btrfs_item_key_to_cpu(eb: leaf, cpu_key: &key, nr: path->slots[0]);
653
654	if (iref) {
655	/*
656	* If type is invalid, we should have bailed out earlier than
657	* this call.
658	*/
659	type = btrfs_get_extent_inline_ref_type(eb: leaf, iref, is_data: BTRFS_REF_TYPE_DATA);
660	ASSERT(type != BTRFS_REF_TYPE_INVALID);
661	if (type == BTRFS_EXTENT_DATA_REF_KEY) {
662	ref1 = (struct btrfs_extent_data_ref *)(&iref->offset);
663	num_refs = btrfs_extent_data_ref_count(eb: leaf, s: ref1);
664	} else {
665	ref2 = (struct btrfs_shared_data_ref *)(iref + 1);
666	num_refs = btrfs_shared_data_ref_count(eb: leaf, s: ref2);
667	}
668	} else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
669	ref1 = btrfs_item_ptr(leaf, path->slots[0],
670	struct btrfs_extent_data_ref);
671	num_refs = btrfs_extent_data_ref_count(eb: leaf, s: ref1);
672	} else if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
673	ref2 = btrfs_item_ptr(leaf, path->slots[0],
674	struct btrfs_shared_data_ref);
675	num_refs = btrfs_shared_data_ref_count(eb: leaf, s: ref2);
676	} else {
677	WARN_ON(1);
678	}
679	return num_refs;
680	}
681
682	static noinline int lookup_tree_block_ref(struct btrfs_trans_handle *trans,
683	struct btrfs_path *path,
684	u64 bytenr, u64 parent,
685	u64 root_objectid)
686	{
687	struct btrfs_root *root = btrfs_extent_root(fs_info: trans->fs_info, bytenr);
688	struct btrfs_key key;
689	int ret;
690
691	key.objectid = bytenr;
692	if (parent) {
693	key.type = BTRFS_SHARED_BLOCK_REF_KEY;
694	key.offset = parent;
695	} else {
696	key.type = BTRFS_TREE_BLOCK_REF_KEY;
697	key.offset = root_objectid;
698	}
699
700	ret = btrfs_search_slot(trans, root, key: &key, p: path, ins_len: -1, cow: 1);
701	if (ret > 0)
702	ret = -ENOENT;
703	return ret;
704	}
705
706	static noinline int insert_tree_block_ref(struct btrfs_trans_handle *trans,
707	struct btrfs_path *path,
708	u64 bytenr, u64 parent,
709	u64 root_objectid)
710	{
711	struct btrfs_root *root = btrfs_extent_root(fs_info: trans->fs_info, bytenr);
712	struct btrfs_key key;
713	int ret;
714
715	key.objectid = bytenr;
716	if (parent) {
717	key.type = BTRFS_SHARED_BLOCK_REF_KEY;
718	key.offset = parent;
719	} else {
720	key.type = BTRFS_TREE_BLOCK_REF_KEY;
721	key.offset = root_objectid;
722	}
723
724	ret = btrfs_insert_empty_item(trans, root, path, key: &key, data_size: 0);
725	btrfs_release_path(p: path);
726	return ret;
727	}
728
729	static inline int extent_ref_type(u64 parent, u64 owner)
730	{
731	int type;
732	if (owner < BTRFS_FIRST_FREE_OBJECTID) {
733	if (parent > 0)
734	type = BTRFS_SHARED_BLOCK_REF_KEY;
735	else
736	type = BTRFS_TREE_BLOCK_REF_KEY;
737	} else {
738	if (parent > 0)
739	type = BTRFS_SHARED_DATA_REF_KEY;
740	else
741	type = BTRFS_EXTENT_DATA_REF_KEY;
742	}
743	return type;
744	}
745
746	static int find_next_key(struct btrfs_path *path, int level,
747	struct btrfs_key *key)
748
749	{
750	for (; level < BTRFS_MAX_LEVEL; level++) {
751	if (!path->nodes[level])
752	break;
753	if (path->slots[level] + 1 >=
754	btrfs_header_nritems(eb: path->nodes[level]))
755	continue;
756	if (level == 0)
757	btrfs_item_key_to_cpu(eb: path->nodes[level], cpu_key: key,
758	nr: path->slots[level] + 1);
759	else
760	btrfs_node_key_to_cpu(eb: path->nodes[level], cpu_key: key,
761	nr: path->slots[level] + 1);
762	return 0;
763	}
764	return 1;
765	}
766
767	/*
768	* look for inline back ref. if back ref is found, *ref_ret is set
769	* to the address of inline back ref, and 0 is returned.
770	*
771	* if back ref isn't found, *ref_ret is set to the address where it
772	* should be inserted, and -ENOENT is returned.
773	*
774	* if insert is true and there are too many inline back refs, the path
775	* points to the extent item, and -EAGAIN is returned.
776	*
777	* NOTE: inline back refs are ordered in the same way that back ref
778	* items in the tree are ordered.
779	*/
780	static noinline_for_stack
781	int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
782	struct btrfs_path *path,
783	struct btrfs_extent_inline_ref **ref_ret,
784	u64 bytenr, u64 num_bytes,
785	u64 parent, u64 root_objectid,
786	u64 owner, u64 offset, int insert)
787	{
788	struct btrfs_fs_info *fs_info = trans->fs_info;
789	struct btrfs_root *root = btrfs_extent_root(fs_info, bytenr);
790	struct btrfs_key key;
791	struct extent_buffer *leaf;
792	struct btrfs_extent_item *ei;
793	struct btrfs_extent_inline_ref *iref;
794	u64 flags;
795	u64 item_size;
796	unsigned long ptr;
797	unsigned long end;
798	int extra_size;
799	int type;
800	int want;
801	int ret;
802	bool skinny_metadata = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
803	int needed;
804
805	key.objectid = bytenr;
806	key.type = BTRFS_EXTENT_ITEM_KEY;
807	key.offset = num_bytes;
808
809	want = extent_ref_type(parent, owner);
810	if (insert) {
811	extra_size = btrfs_extent_inline_ref_size(type: want);
812	path->search_for_extension = 1;
813	path->keep_locks = 1;
814	} else
815	extra_size = -1;
816
817	/*
818	* Owner is our level, so we can just add one to get the level for the
819	* block we are interested in.
820	*/
821	if (skinny_metadata && owner < BTRFS_FIRST_FREE_OBJECTID) {
822	key.type = BTRFS_METADATA_ITEM_KEY;
823	key.offset = owner;
824	}
825
826	again:
827	ret = btrfs_search_slot(trans, root, key: &key, p: path, ins_len: extra_size, cow: 1);
828	if (ret < 0)
829	goto out;
830
831	/*
832	* We may be a newly converted file system which still has the old fat
833	* extent entries for metadata, so try and see if we have one of those.
834	*/
835	if (ret > 0 && skinny_metadata) {
836	skinny_metadata = false;
837	if (path->slots[0]) {
838	path->slots[0]--;
839	btrfs_item_key_to_cpu(eb: path->nodes[0], cpu_key: &key,
840	nr: path->slots[0]);
841	if (key.objectid == bytenr &&
842	key.type == BTRFS_EXTENT_ITEM_KEY &&
843	key.offset == num_bytes)
844	ret = 0;
845	}
846	if (ret) {
847	key.objectid = bytenr;
848	key.type = BTRFS_EXTENT_ITEM_KEY;
849	key.offset = num_bytes;
850	btrfs_release_path(p: path);
851	goto again;
852	}
853	}
854
855	if (ret && !insert) {
856	ret = -ENOENT;
857	goto out;
858	} else if (WARN_ON(ret)) {
859	btrfs_print_leaf(l: path->nodes[0]);
860	btrfs_err(fs_info,
861	"extent item not found for insert, bytenr %llu num_bytes %llu parent %llu root_objectid %llu owner %llu offset %llu",
862	bytenr, num_bytes, parent, root_objectid, owner,
863	offset);
864	ret = -EUCLEAN;
865	goto out;
866	}
867
868	leaf = path->nodes[0];
869	item_size = btrfs_item_size(eb: leaf, slot: path->slots[0]);
870	if (unlikely(item_size < sizeof(*ei))) {
871	ret = -EUCLEAN;
872	btrfs_err(fs_info,
873	"unexpected extent item size, has %llu expect >= %zu",
874	item_size, sizeof(*ei));
875	btrfs_abort_transaction(trans, ret);
876	goto out;
877	}
878
879	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
880	flags = btrfs_extent_flags(eb: leaf, s: ei);
881
882	ptr = (unsigned long)(ei + 1);
883	end = (unsigned long)ei + item_size;
884
885	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK && !skinny_metadata) {
886	ptr += sizeof(struct btrfs_tree_block_info);
887	BUG_ON(ptr > end);
888	}
889
890	if (owner >= BTRFS_FIRST_FREE_OBJECTID)
891	needed = BTRFS_REF_TYPE_DATA;
892	else
893	needed = BTRFS_REF_TYPE_BLOCK;
894
895	ret = -ENOENT;
896	while (ptr < end) {
897	iref = (struct btrfs_extent_inline_ref *)ptr;
898	type = btrfs_get_extent_inline_ref_type(eb: leaf, iref, is_data: needed);
899	if (type == BTRFS_EXTENT_OWNER_REF_KEY) {
900	ASSERT(btrfs_fs_incompat(fs_info, SIMPLE_QUOTA));
901	ptr += btrfs_extent_inline_ref_size(type);
902	continue;
903	}
904	if (type == BTRFS_REF_TYPE_INVALID) {
905	ret = -EUCLEAN;
906	goto out;
907	}
908
909	if (want < type)
910	break;
911	if (want > type) {
912	ptr += btrfs_extent_inline_ref_size(type);
913	continue;
914	}
915
916	if (type == BTRFS_EXTENT_DATA_REF_KEY) {
917	struct btrfs_extent_data_ref *dref;
918	dref = (struct btrfs_extent_data_ref *)(&iref->offset);
919	if (match_extent_data_ref(leaf, ref: dref, root_objectid,
920	owner, offset)) {
921	ret = 0;
922	break;
923	}
924	if (hash_extent_data_ref_item(leaf, ref: dref) <
925	hash_extent_data_ref(root_objectid, owner, offset))
926	break;
927	} else {
928	u64 ref_offset;
929	ref_offset = btrfs_extent_inline_ref_offset(eb: leaf, s: iref);
930	if (parent > 0) {
931	if (parent == ref_offset) {
932	ret = 0;
933	break;
934	}
935	if (ref_offset < parent)
936	break;
937	} else {
938	if (root_objectid == ref_offset) {
939	ret = 0;
940	break;
941	}
942	if (ref_offset < root_objectid)
943	break;
944	}
945	}
946	ptr += btrfs_extent_inline_ref_size(type);
947	}
948
949	if (unlikely(ptr > end)) {
950	ret = -EUCLEAN;
951	btrfs_print_leaf(l: path->nodes[0]);
952	btrfs_crit(fs_info,
953	"overrun extent record at slot %d while looking for inline extent for root %llu owner %llu offset %llu parent %llu",
954	path->slots[0], root_objectid, owner, offset, parent);
955	goto out;
956	}
957
958	if (ret == -ENOENT && insert) {
959	if (item_size + extra_size >=
960	BTRFS_MAX_EXTENT_ITEM_SIZE(root)) {
961	ret = -EAGAIN;
962	goto out;
963	}
964	/*
965	* To add new inline back ref, we have to make sure
966	* there is no corresponding back ref item.
967	* For simplicity, we just do not add new inline back
968	* ref if there is any kind of item for this block
969	*/
970	if (find_next_key(path, level: 0, key: &key) == 0 &&
971	key.objectid == bytenr &&
972	key.type < BTRFS_BLOCK_GROUP_ITEM_KEY) {
973	ret = -EAGAIN;
974	goto out;
975	}
976	}
977	*ref_ret = (struct btrfs_extent_inline_ref *)ptr;
978	out:
979	if (insert) {
980	path->keep_locks = 0;
981	path->search_for_extension = 0;
982	btrfs_unlock_up_safe(path, level: 1);
983	}
984	return ret;
985	}
986
987	/*
988	* helper to add new inline back ref
989	*/
990	static noinline_for_stack
991	void setup_inline_extent_backref(struct btrfs_trans_handle *trans,
992	struct btrfs_path *path,
993	struct btrfs_extent_inline_ref *iref,
994	u64 parent, u64 root_objectid,
995	u64 owner, u64 offset, int refs_to_add,
996	struct btrfs_delayed_extent_op *extent_op)
997	{
998	struct extent_buffer *leaf;
999	struct btrfs_extent_item *ei;
1000	unsigned long ptr;
1001	unsigned long end;
1002	unsigned long item_offset;
1003	u64 refs;
1004	int size;
1005	int type;
1006
1007	leaf = path->nodes[0];
1008	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1009	item_offset = (unsigned long)iref - (unsigned long)ei;
1010
1011	type = extent_ref_type(parent, owner);
1012	size = btrfs_extent_inline_ref_size(type);
1013
1014	btrfs_extend_item(trans, path, data_size: size);
1015
1016	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1017	refs = btrfs_extent_refs(eb: leaf, s: ei);
1018	refs += refs_to_add;
1019	btrfs_set_extent_refs(eb: leaf, s: ei, val: refs);
1020	if (extent_op)
1021	__run_delayed_extent_op(extent_op, leaf, ei);
1022
1023	ptr = (unsigned long)ei + item_offset;
1024	end = (unsigned long)ei + btrfs_item_size(eb: leaf, slot: path->slots[0]);
1025	if (ptr < end - size)
1026	memmove_extent_buffer(dst: leaf, dst_offset: ptr + size, src_offset: ptr,
1027	len: end - size - ptr);
1028
1029	iref = (struct btrfs_extent_inline_ref *)ptr;
1030	btrfs_set_extent_inline_ref_type(eb: leaf, s: iref, val: type);
1031	if (type == BTRFS_EXTENT_DATA_REF_KEY) {
1032	struct btrfs_extent_data_ref *dref;
1033	dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1034	btrfs_set_extent_data_ref_root(eb: leaf, s: dref, val: root_objectid);
1035	btrfs_set_extent_data_ref_objectid(eb: leaf, s: dref, val: owner);
1036	btrfs_set_extent_data_ref_offset(eb: leaf, s: dref, val: offset);
1037	btrfs_set_extent_data_ref_count(eb: leaf, s: dref, val: refs_to_add);
1038	} else if (type == BTRFS_SHARED_DATA_REF_KEY) {
1039	struct btrfs_shared_data_ref *sref;
1040	sref = (struct btrfs_shared_data_ref *)(iref + 1);
1041	btrfs_set_shared_data_ref_count(eb: leaf, s: sref, val: refs_to_add);
1042	btrfs_set_extent_inline_ref_offset(eb: leaf, s: iref, val: parent);
1043	} else if (type == BTRFS_SHARED_BLOCK_REF_KEY) {
1044	btrfs_set_extent_inline_ref_offset(eb: leaf, s: iref, val: parent);
1045	} else {
1046	btrfs_set_extent_inline_ref_offset(eb: leaf, s: iref, val: root_objectid);
1047	}
1048	btrfs_mark_buffer_dirty(trans, buf: leaf);
1049	}
1050
1051	static int lookup_extent_backref(struct btrfs_trans_handle *trans,
1052	struct btrfs_path *path,
1053	struct btrfs_extent_inline_ref **ref_ret,
1054	u64 bytenr, u64 num_bytes, u64 parent,
1055	u64 root_objectid, u64 owner, u64 offset)
1056	{
1057	int ret;
1058
1059	ret = lookup_inline_extent_backref(trans, path, ref_ret, bytenr,
1060	num_bytes, parent, root_objectid,
1061	owner, offset, insert: 0);
1062	if (ret != -ENOENT)
1063	return ret;
1064
1065	btrfs_release_path(p: path);
1066	*ref_ret = NULL;
1067
1068	if (owner < BTRFS_FIRST_FREE_OBJECTID) {
1069	ret = lookup_tree_block_ref(trans, path, bytenr, parent,
1070	root_objectid);
1071	} else {
1072	ret = lookup_extent_data_ref(trans, path, bytenr, parent,
1073	root_objectid, owner, offset);
1074	}
1075	return ret;
1076	}
1077
1078	/*
1079	* helper to update/remove inline back ref
1080	*/
1081	static noinline_for_stack int update_inline_extent_backref(
1082	struct btrfs_trans_handle *trans,
1083	struct btrfs_path *path,
1084	struct btrfs_extent_inline_ref *iref,
1085	int refs_to_mod,
1086	struct btrfs_delayed_extent_op *extent_op)
1087	{
1088	struct extent_buffer *leaf = path->nodes[0];
1089	struct btrfs_fs_info *fs_info = leaf->fs_info;
1090	struct btrfs_extent_item *ei;
1091	struct btrfs_extent_data_ref *dref = NULL;
1092	struct btrfs_shared_data_ref *sref = NULL;
1093	unsigned long ptr;
1094	unsigned long end;
1095	u32 item_size;
1096	int size;
1097	int type;
1098	u64 refs;
1099
1100	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1101	refs = btrfs_extent_refs(eb: leaf, s: ei);
1102	if (unlikely(refs_to_mod < 0 && refs + refs_to_mod <= 0)) {
1103	struct btrfs_key key;
1104	u32 extent_size;
1105
1106	btrfs_item_key_to_cpu(eb: leaf, cpu_key: &key, nr: path->slots[0]);
1107	if (key.type == BTRFS_METADATA_ITEM_KEY)
1108	extent_size = fs_info->nodesize;
1109	else
1110	extent_size = key.offset;
1111	btrfs_print_leaf(l: leaf);
1112	btrfs_err(fs_info,
1113	"invalid refs_to_mod for extent %llu num_bytes %u, has %d expect >= -%llu",
1114	key.objectid, extent_size, refs_to_mod, refs);
1115	return -EUCLEAN;
1116	}
1117	refs += refs_to_mod;
1118	btrfs_set_extent_refs(eb: leaf, s: ei, val: refs);
1119	if (extent_op)
1120	__run_delayed_extent_op(extent_op, leaf, ei);
1121
1122	type = btrfs_get_extent_inline_ref_type(eb: leaf, iref, is_data: BTRFS_REF_TYPE_ANY);
1123	/*
1124	* Function btrfs_get_extent_inline_ref_type() has already printed
1125	* error messages.
1126	*/
1127	if (unlikely(type == BTRFS_REF_TYPE_INVALID))
1128	return -EUCLEAN;
1129
1130	if (type == BTRFS_EXTENT_DATA_REF_KEY) {
1131	dref = (struct btrfs_extent_data_ref *)(&iref->offset);
1132	refs = btrfs_extent_data_ref_count(eb: leaf, s: dref);
1133	} else if (type == BTRFS_SHARED_DATA_REF_KEY) {
1134	sref = (struct btrfs_shared_data_ref *)(iref + 1);
1135	refs = btrfs_shared_data_ref_count(eb: leaf, s: sref);
1136	} else {
1137	refs = 1;
1138	/*
1139	* For tree blocks we can only drop one ref for it, and tree
1140	* blocks should not have refs > 1.
1141	*
1142	* Furthermore if we're inserting a new inline backref, we
1143	* won't reach this path either. That would be
1144	* setup_inline_extent_backref().
1145	*/
1146	if (unlikely(refs_to_mod != -1)) {
1147	struct btrfs_key key;
1148
1149	btrfs_item_key_to_cpu(eb: leaf, cpu_key: &key, nr: path->slots[0]);
1150
1151	btrfs_print_leaf(l: leaf);
1152	btrfs_err(fs_info,
1153	"invalid refs_to_mod for tree block %llu, has %d expect -1",
1154	key.objectid, refs_to_mod);
1155	return -EUCLEAN;
1156	}
1157	}
1158
1159	if (unlikely(refs_to_mod < 0 && refs < -refs_to_mod)) {
1160	struct btrfs_key key;
1161	u32 extent_size;
1162
1163	btrfs_item_key_to_cpu(eb: leaf, cpu_key: &key, nr: path->slots[0]);
1164	if (key.type == BTRFS_METADATA_ITEM_KEY)
1165	extent_size = fs_info->nodesize;
1166	else
1167	extent_size = key.offset;
1168	btrfs_print_leaf(l: leaf);
1169	btrfs_err(fs_info,
1170	"invalid refs_to_mod for backref entry, iref %lu extent %llu num_bytes %u, has %d expect >= -%llu",
1171	(unsigned long)iref, key.objectid, extent_size,
1172	refs_to_mod, refs);
1173	return -EUCLEAN;
1174	}
1175	refs += refs_to_mod;
1176
1177	if (refs > 0) {
1178	if (type == BTRFS_EXTENT_DATA_REF_KEY)
1179	btrfs_set_extent_data_ref_count(eb: leaf, s: dref, val: refs);
1180	else
1181	btrfs_set_shared_data_ref_count(eb: leaf, s: sref, val: refs);
1182	} else {
1183	size = btrfs_extent_inline_ref_size(type);
1184	item_size = btrfs_item_size(eb: leaf, slot: path->slots[0]);
1185	ptr = (unsigned long)iref;
1186	end = (unsigned long)ei + item_size;
1187	if (ptr + size < end)
1188	memmove_extent_buffer(dst: leaf, dst_offset: ptr, src_offset: ptr + size,
1189	len: end - ptr - size);
1190	item_size -= size;
1191	btrfs_truncate_item(trans, path, new_size: item_size, from_end: 1);
1192	}
1193	btrfs_mark_buffer_dirty(trans, buf: leaf);
1194	return 0;
1195	}
1196
1197	static noinline_for_stack
1198	int insert_inline_extent_backref(struct btrfs_trans_handle *trans,
1199	struct btrfs_path *path,
1200	u64 bytenr, u64 num_bytes, u64 parent,
1201	u64 root_objectid, u64 owner,
1202	u64 offset, int refs_to_add,
1203	struct btrfs_delayed_extent_op *extent_op)
1204	{
1205	struct btrfs_extent_inline_ref *iref;
1206	int ret;
1207
1208	ret = lookup_inline_extent_backref(trans, path, ref_ret: &iref, bytenr,
1209	num_bytes, parent, root_objectid,
1210	owner, offset, insert: 1);
1211	if (ret == 0) {
1212	/*
1213	* We're adding refs to a tree block we already own, this
1214	* should not happen at all.
1215	*/
1216	if (owner < BTRFS_FIRST_FREE_OBJECTID) {
1217	btrfs_print_leaf(l: path->nodes[0]);
1218	btrfs_crit(trans->fs_info,
1219	"adding refs to an existing tree ref, bytenr %llu num_bytes %llu root_objectid %llu slot %u",
1220	bytenr, num_bytes, root_objectid, path->slots[0]);
1221	return -EUCLEAN;
1222	}
1223	ret = update_inline_extent_backref(trans, path, iref,
1224	refs_to_mod: refs_to_add, extent_op);
1225	} else if (ret == -ENOENT) {
1226	setup_inline_extent_backref(trans, path, iref, parent,
1227	root_objectid, owner, offset,
1228	refs_to_add, extent_op);
1229	ret = 0;
1230	}
1231	return ret;
1232	}
1233
1234	static int remove_extent_backref(struct btrfs_trans_handle *trans,
1235	struct btrfs_root *root,
1236	struct btrfs_path *path,
1237	struct btrfs_extent_inline_ref *iref,
1238	int refs_to_drop, int is_data)
1239	{
1240	int ret = 0;
1241
1242	BUG_ON(!is_data && refs_to_drop != 1);
1243	if (iref)
1244	ret = update_inline_extent_backref(trans, path, iref,
1245	refs_to_mod: -refs_to_drop, NULL);
1246	else if (is_data)
1247	ret = remove_extent_data_ref(trans, root, path, refs_to_drop);
1248	else
1249	ret = btrfs_del_item(trans, root, path);
1250	return ret;
1251	}
1252
1253	static int btrfs_issue_discard(struct block_device *bdev, u64 start, u64 len,
1254	u64 *discarded_bytes)
1255	{
1256	int j, ret = 0;
1257	u64 bytes_left, end;
1258	u64 aligned_start = ALIGN(start, 1 << SECTOR_SHIFT);
1259
1260	/* Adjust the range to be aligned to 512B sectors if necessary. */
1261	if (start != aligned_start) {
1262	len -= aligned_start - start;
1263	len = round_down(len, 1 << SECTOR_SHIFT);
1264	start = aligned_start;
1265	}
1266
1267	*discarded_bytes = 0;
1268
1269	if (!len)
1270	return 0;
1271
1272	end = start + len;
1273	bytes_left = len;
1274
1275	/* Skip any superblocks on this device. */
1276	for (j = 0; j < BTRFS_SUPER_MIRROR_MAX; j++) {
1277	u64 sb_start = btrfs_sb_offset(mirror: j);
1278	u64 sb_end = sb_start + BTRFS_SUPER_INFO_SIZE;
1279	u64 size = sb_start - start;
1280
1281	if (!in_range(sb_start, start, bytes_left) &&
1282	!in_range(sb_end, start, bytes_left) &&
1283	!in_range(start, sb_start, BTRFS_SUPER_INFO_SIZE))
1284	continue;
1285
1286	/*
1287	* Superblock spans beginning of range. Adjust start and
1288	* try again.
1289	*/
1290	if (sb_start <= start) {
1291	start += sb_end - start;
1292	if (start > end) {
1293	bytes_left = 0;
1294	break;
1295	}
1296	bytes_left = end - start;
1297	continue;
1298	}
1299
1300	if (size) {
1301	ret = blkdev_issue_discard(bdev, sector: start >> SECTOR_SHIFT,
1302	nr_sects: size >> SECTOR_SHIFT,
1303	GFP_NOFS);
1304	if (!ret)
1305	*discarded_bytes += size;
1306	else if (ret != -EOPNOTSUPP)
1307	return ret;
1308	}
1309
1310	start = sb_end;
1311	if (start > end) {
1312	bytes_left = 0;
1313	break;
1314	}
1315	bytes_left = end - start;
1316	}
1317
1318	if (bytes_left) {
1319	ret = blkdev_issue_discard(bdev, sector: start >> SECTOR_SHIFT,
1320	nr_sects: bytes_left >> SECTOR_SHIFT,
1321	GFP_NOFS);
1322	if (!ret)
1323	*discarded_bytes += bytes_left;
1324	}
1325	return ret;
1326	}
1327
1328	static int do_discard_extent(struct btrfs_discard_stripe *stripe, u64 *bytes)
1329	{
1330	struct btrfs_device *dev = stripe->dev;
1331	struct btrfs_fs_info *fs_info = dev->fs_info;
1332	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
1333	u64 phys = stripe->physical;
1334	u64 len = stripe->length;
1335	u64 discarded = 0;
1336	int ret = 0;
1337
1338	/* Zone reset on a zoned filesystem */
1339	if (btrfs_can_zone_reset(device: dev, physical: phys, length: len)) {
1340	u64 src_disc;
1341
1342	ret = btrfs_reset_device_zone(device: dev, physical: phys, length: len, bytes: &discarded);
1343	if (ret)
1344	goto out;
1345
1346	if (!btrfs_dev_replace_is_ongoing(dev_replace) ||
1347	dev != dev_replace->srcdev)
1348	goto out;
1349
1350	src_disc = discarded;
1351
1352	/* Send to replace target as well */
1353	ret = btrfs_reset_device_zone(device: dev_replace->tgtdev, physical: phys, length: len,
1354	bytes: &discarded);
1355	discarded += src_disc;
1356	} else if (bdev_max_discard_sectors(bdev: stripe->dev->bdev)) {
1357	ret = btrfs_issue_discard(bdev: dev->bdev, start: phys, len, discarded_bytes: &discarded);
1358	} else {
1359	ret = 0;
1360	*bytes = 0;
1361	}
1362
1363	out:
1364	*bytes = discarded;
1365	return ret;
1366	}
1367
1368	int btrfs_discard_extent(struct btrfs_fs_info *fs_info, u64 bytenr,
1369	u64 num_bytes, u64 *actual_bytes)
1370	{
1371	int ret = 0;
1372	u64 discarded_bytes = 0;
1373	u64 end = bytenr + num_bytes;
1374	u64 cur = bytenr;
1375
1376	/*
1377	* Avoid races with device replace and make sure the devices in the
1378	* stripes don't go away while we are discarding.
1379	*/
1380	btrfs_bio_counter_inc_blocked(fs_info);
1381	while (cur < end) {
1382	struct btrfs_discard_stripe *stripes;
1383	unsigned int num_stripes;
1384	int i;
1385
1386	num_bytes = end - cur;
1387	stripes = btrfs_map_discard(fs_info, logical: cur, length_ret: &num_bytes, num_stripes: &num_stripes);
1388	if (IS_ERR(ptr: stripes)) {
1389	ret = PTR_ERR(ptr: stripes);
1390	if (ret == -EOPNOTSUPP)
1391	ret = 0;
1392	break;
1393	}
1394
1395	for (i = 0; i < num_stripes; i++) {
1396	struct btrfs_discard_stripe *stripe = stripes + i;
1397	u64 bytes;
1398
1399	if (!stripe->dev->bdev) {
1400	ASSERT(btrfs_test_opt(fs_info, DEGRADED));
1401	continue;
1402	}
1403
1404	if (!test_bit(BTRFS_DEV_STATE_WRITEABLE,
1405	&stripe->dev->dev_state))
1406	continue;
1407
1408	ret = do_discard_extent(stripe, bytes: &bytes);
1409	if (ret) {
1410	/*
1411	* Keep going if discard is not supported by the
1412	* device.
1413	*/
1414	if (ret != -EOPNOTSUPP)
1415	break;
1416	ret = 0;
1417	} else {
1418	discarded_bytes += bytes;
1419	}
1420	}
1421	kfree(objp: stripes);
1422	if (ret)
1423	break;
1424	cur += num_bytes;
1425	}
1426	btrfs_bio_counter_dec(fs_info);
1427	if (actual_bytes)
1428	*actual_bytes = discarded_bytes;
1429	return ret;
1430	}
1431
1432	/* Can return -ENOMEM */
1433	int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
1434	struct btrfs_ref *generic_ref)
1435	{
1436	struct btrfs_fs_info *fs_info = trans->fs_info;
1437	int ret;
1438
1439	ASSERT(generic_ref->type != BTRFS_REF_NOT_SET &&
1440	generic_ref->action);
1441	BUG_ON(generic_ref->type == BTRFS_REF_METADATA &&
1442	generic_ref->tree_ref.ref_root == BTRFS_TREE_LOG_OBJECTID);
1443
1444	if (generic_ref->type == BTRFS_REF_METADATA)
1445	ret = btrfs_add_delayed_tree_ref(trans, generic_ref, NULL);
1446	else
1447	ret = btrfs_add_delayed_data_ref(trans, generic_ref, reserved: 0);
1448
1449	btrfs_ref_tree_mod(fs_info, generic_ref);
1450
1451	return ret;
1452	}
1453
1454	/*
1455	* Insert backreference for a given extent.
1456	*
1457	* The counterpart is in __btrfs_free_extent(), with examples and more details
1458	* how it works.
1459	*
1460	* @trans: Handle of transaction
1461	*
1462	* @node: The delayed ref node used to get the bytenr/length for
1463	* extent whose references are incremented.
1464	*
1465	* @parent: If this is a shared extent (BTRFS_SHARED_DATA_REF_KEY/
1466	* BTRFS_SHARED_BLOCK_REF_KEY) then it holds the logical
1467	* bytenr of the parent block. Since new extents are always
1468	* created with indirect references, this will only be the case
1469	* when relocating a shared extent. In that case, root_objectid
1470	* will be BTRFS_TREE_RELOC_OBJECTID. Otherwise, parent must
1471	* be 0
1472	*
1473	* @root_objectid: The id of the root where this modification has originated,
1474	* this can be either one of the well-known metadata trees or
1475	* the subvolume id which references this extent.
1476	*
1477	* @owner: For data extents it is the inode number of the owning file.
1478	* For metadata extents this parameter holds the level in the
1479	* tree of the extent.
1480	*
1481	* @offset: For metadata extents the offset is ignored and is currently
1482	* always passed as 0. For data extents it is the fileoffset
1483	* this extent belongs to.
1484	*
1485	* @extent_op Pointer to a structure, holding information necessary when
1486	* updating a tree block's flags
1487	*
1488	*/
1489	static int __btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
1490	struct btrfs_delayed_ref_node *node,
1491	u64 parent, u64 root_objectid,
1492	u64 owner, u64 offset,
1493	struct btrfs_delayed_extent_op *extent_op)
1494	{
1495	struct btrfs_path *path;
1496	struct extent_buffer *leaf;
1497	struct btrfs_extent_item *item;
1498	struct btrfs_key key;
1499	u64 bytenr = node->bytenr;
1500	u64 num_bytes = node->num_bytes;
1501	u64 refs;
1502	int refs_to_add = node->ref_mod;
1503	int ret;
1504
1505	path = btrfs_alloc_path();
1506	if (!path)
1507	return -ENOMEM;
1508
1509	/* this will setup the path even if it fails to insert the back ref */
1510	ret = insert_inline_extent_backref(trans, path, bytenr, num_bytes,
1511	parent, root_objectid, owner,
1512	offset, refs_to_add, extent_op);
1513	if ((ret < 0 && ret != -EAGAIN) || !ret)
1514	goto out;
1515
1516	/*
1517	* Ok we had -EAGAIN which means we didn't have space to insert and
1518	* inline extent ref, so just update the reference count and add a
1519	* normal backref.
1520	*/
1521	leaf = path->nodes[0];
1522	btrfs_item_key_to_cpu(eb: leaf, cpu_key: &key, nr: path->slots[0]);
1523	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1524	refs = btrfs_extent_refs(eb: leaf, s: item);
1525	btrfs_set_extent_refs(eb: leaf, s: item, val: refs + refs_to_add);
1526	if (extent_op)
1527	__run_delayed_extent_op(extent_op, leaf, ei: item);
1528
1529	btrfs_mark_buffer_dirty(trans, buf: leaf);
1530	btrfs_release_path(p: path);
1531
1532	/* now insert the actual backref */
1533	if (owner < BTRFS_FIRST_FREE_OBJECTID)
1534	ret = insert_tree_block_ref(trans, path, bytenr, parent,
1535	root_objectid);
1536	else
1537	ret = insert_extent_data_ref(trans, path, bytenr, parent,
1538	root_objectid, owner, offset,
1539	refs_to_add);
1540
1541	if (ret)
1542	btrfs_abort_transaction(trans, ret);
1543	out:
1544	btrfs_free_path(p: path);
1545	return ret;
1546	}
1547
1548	static void free_head_ref_squota_rsv(struct btrfs_fs_info *fs_info,
1549	struct btrfs_delayed_ref_head *href)
1550	{
1551	u64 root = href->owning_root;
1552
1553	/*
1554	* Don't check must_insert_reserved, as this is called from contexts
1555	* where it has already been unset.
1556	*/
1557	if (btrfs_qgroup_mode(fs_info) != BTRFS_QGROUP_MODE_SIMPLE ||
1558	!href->is_data || !is_fstree(rootid: root))
1559	return;
1560
1561	btrfs_qgroup_free_refroot(fs_info, ref_root: root, num_bytes: href->reserved_bytes,
1562	type: BTRFS_QGROUP_RSV_DATA);
1563	}
1564
1565	static int run_delayed_data_ref(struct btrfs_trans_handle *trans,
1566	struct btrfs_delayed_ref_head *href,
1567	struct btrfs_delayed_ref_node *node,
1568	struct btrfs_delayed_extent_op *extent_op,
1569	bool insert_reserved)
1570	{
1571	int ret = 0;
1572	struct btrfs_delayed_data_ref *ref;
1573	u64 parent = 0;
1574	u64 flags = 0;
1575
1576	ref = btrfs_delayed_node_to_data_ref(node);
1577	trace_run_delayed_data_ref(fs_info: trans->fs_info, ref: node, full_ref: ref, action: node->action);
1578
1579	if (node->type == BTRFS_SHARED_DATA_REF_KEY)
1580	parent = ref->parent;
1581
1582	if (node->action == BTRFS_ADD_DELAYED_REF && insert_reserved) {
1583	struct btrfs_key key;
1584	struct btrfs_squota_delta delta = {
1585	.root = href->owning_root,
1586	.num_bytes = node->num_bytes,
1587	.is_data = true,
1588	.is_inc = true,
1589	.generation = trans->transid,
1590	};
1591
1592	if (extent_op)
1593	flags |= extent_op->flags_to_set;
1594
1595	key.objectid = node->bytenr;
1596	key.type = BTRFS_EXTENT_ITEM_KEY;
1597	key.offset = node->num_bytes;
1598
1599	ret = alloc_reserved_file_extent(trans, parent, root_objectid: ref->root,
1600	flags, owner: ref->objectid,
1601	offset: ref->offset, ins: &key,
1602	ref_mod: node->ref_mod, oref_root: href->owning_root);
1603	free_head_ref_squota_rsv(fs_info: trans->fs_info, href);
1604	if (!ret)
1605	ret = btrfs_record_squota_delta(fs_info: trans->fs_info, delta: &delta);
1606	} else if (node->action == BTRFS_ADD_DELAYED_REF) {
1607	ret = __btrfs_inc_extent_ref(trans, node, parent, root_objectid: ref->root,
1608	owner: ref->objectid, offset: ref->offset,
1609	extent_op);
1610	} else if (node->action == BTRFS_DROP_DELAYED_REF) {
1611	ret = __btrfs_free_extent(trans, href, node, parent,
1612	root_objectid: ref->root, owner_objectid: ref->objectid,
1613	owner_offset: ref->offset, extra_op: extent_op);
1614	} else {
1615	BUG();
1616	}
1617	return ret;
1618	}
1619
1620	static void __run_delayed_extent_op(struct btrfs_delayed_extent_op *extent_op,
1621	struct extent_buffer *leaf,
1622	struct btrfs_extent_item *ei)
1623	{
1624	u64 flags = btrfs_extent_flags(eb: leaf, s: ei);
1625	if (extent_op->update_flags) {
1626	flags |= extent_op->flags_to_set;
1627	btrfs_set_extent_flags(eb: leaf, s: ei, val: flags);
1628	}
1629
1630	if (extent_op->update_key) {
1631	struct btrfs_tree_block_info *bi;
1632	BUG_ON(!(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK));
1633	bi = (struct btrfs_tree_block_info *)(ei + 1);
1634	btrfs_set_tree_block_key(eb: leaf, item: bi, key: &extent_op->key);
1635	}
1636	}
1637
1638	static int run_delayed_extent_op(struct btrfs_trans_handle *trans,
1639	struct btrfs_delayed_ref_head *head,
1640	struct btrfs_delayed_extent_op *extent_op)
1641	{
1642	struct btrfs_fs_info *fs_info = trans->fs_info;
1643	struct btrfs_root *root;
1644	struct btrfs_key key;
1645	struct btrfs_path *path;
1646	struct btrfs_extent_item *ei;
1647	struct extent_buffer *leaf;
1648	u32 item_size;
1649	int ret;
1650	int metadata = 1;
1651
1652	if (TRANS_ABORTED(trans))
1653	return 0;
1654
1655	if (!btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1656	metadata = 0;
1657
1658	path = btrfs_alloc_path();
1659	if (!path)
1660	return -ENOMEM;
1661
1662	key.objectid = head->bytenr;
1663
1664	if (metadata) {
1665	key.type = BTRFS_METADATA_ITEM_KEY;
1666	key.offset = extent_op->level;
1667	} else {
1668	key.type = BTRFS_EXTENT_ITEM_KEY;
1669	key.offset = head->num_bytes;
1670	}
1671
1672	root = btrfs_extent_root(fs_info, bytenr: key.objectid);
1673	again:
1674	ret = btrfs_search_slot(trans, root, key: &key, p: path, ins_len: 0, cow: 1);
1675	if (ret < 0) {
1676	goto out;
1677	} else if (ret > 0) {
1678	if (metadata) {
1679	if (path->slots[0] > 0) {
1680	path->slots[0]--;
1681	btrfs_item_key_to_cpu(eb: path->nodes[0], cpu_key: &key,
1682	nr: path->slots[0]);
1683	if (key.objectid == head->bytenr &&
1684	key.type == BTRFS_EXTENT_ITEM_KEY &&
1685	key.offset == head->num_bytes)
1686	ret = 0;
1687	}
1688	if (ret > 0) {
1689	btrfs_release_path(p: path);
1690	metadata = 0;
1691
1692	key.objectid = head->bytenr;
1693	key.offset = head->num_bytes;
1694	key.type = BTRFS_EXTENT_ITEM_KEY;
1695	goto again;
1696	}
1697	} else {
1698	ret = -EUCLEAN;
1699	btrfs_err(fs_info,
1700	"missing extent item for extent %llu num_bytes %llu level %d",
1701	head->bytenr, head->num_bytes, extent_op->level);
1702	goto out;
1703	}
1704	}
1705
1706	leaf = path->nodes[0];
1707	item_size = btrfs_item_size(eb: leaf, slot: path->slots[0]);
1708
1709	if (unlikely(item_size < sizeof(*ei))) {
1710	ret = -EUCLEAN;
1711	btrfs_err(fs_info,
1712	"unexpected extent item size, has %u expect >= %zu",
1713	item_size, sizeof(*ei));
1714	btrfs_abort_transaction(trans, ret);
1715	goto out;
1716	}
1717
1718	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
1719	__run_delayed_extent_op(extent_op, leaf, ei);
1720
1721	btrfs_mark_buffer_dirty(trans, buf: leaf);
1722	out:
1723	btrfs_free_path(p: path);
1724	return ret;
1725	}
1726
1727	static int run_delayed_tree_ref(struct btrfs_trans_handle *trans,
1728	struct btrfs_delayed_ref_head *href,
1729	struct btrfs_delayed_ref_node *node,
1730	struct btrfs_delayed_extent_op *extent_op,
1731	bool insert_reserved)
1732	{
1733	int ret = 0;
1734	struct btrfs_fs_info *fs_info = trans->fs_info;
1735	struct btrfs_delayed_tree_ref *ref;
1736	u64 parent = 0;
1737	u64 ref_root = 0;
1738
1739	ref = btrfs_delayed_node_to_tree_ref(node);
1740	trace_run_delayed_tree_ref(fs_info: trans->fs_info, ref: node, full_ref: ref, action: node->action);
1741
1742	if (node->type == BTRFS_SHARED_BLOCK_REF_KEY)
1743	parent = ref->parent;
1744	ref_root = ref->root;
1745
1746	if (unlikely(node->ref_mod != 1)) {
1747	btrfs_err(trans->fs_info,
1748	"btree block %llu has %d references rather than 1: action %d ref_root %llu parent %llu",
1749	node->bytenr, node->ref_mod, node->action, ref_root,
1750	parent);
1751	return -EUCLEAN;
1752	}
1753	if (node->action == BTRFS_ADD_DELAYED_REF && insert_reserved) {
1754	struct btrfs_squota_delta delta = {
1755	.root = href->owning_root,
1756	.num_bytes = fs_info->nodesize,
1757	.is_data = false,
1758	.is_inc = true,
1759	.generation = trans->transid,
1760	};
1761
1762	BUG_ON(!extent_op || !extent_op->update_flags);
1763	ret = alloc_reserved_tree_block(trans, node, extent_op);
1764	if (!ret)
1765	btrfs_record_squota_delta(fs_info, delta: &delta);
1766	} else if (node->action == BTRFS_ADD_DELAYED_REF) {
1767	ret = __btrfs_inc_extent_ref(trans, node, parent, root_objectid: ref_root,
1768	owner: ref->level, offset: 0, extent_op);
1769	} else if (node->action == BTRFS_DROP_DELAYED_REF) {
1770	ret = __btrfs_free_extent(trans, href, node, parent, root_objectid: ref_root,
1771	owner_objectid: ref->level, owner_offset: 0, extra_op: extent_op);
1772	} else {
1773	BUG();
1774	}
1775	return ret;
1776	}
1777
1778	/* helper function to actually process a single delayed ref entry */
1779	static int run_one_delayed_ref(struct btrfs_trans_handle *trans,
1780	struct btrfs_delayed_ref_head *href,
1781	struct btrfs_delayed_ref_node *node,
1782	struct btrfs_delayed_extent_op *extent_op,
1783	bool insert_reserved)
1784	{
1785	int ret = 0;
1786
1787	if (TRANS_ABORTED(trans)) {
1788	if (insert_reserved) {
1789	btrfs_pin_extent(trans, bytenr: node->bytenr, num: node->num_bytes, reserved: 1);
1790	free_head_ref_squota_rsv(fs_info: trans->fs_info, href);
1791	}
1792	return 0;
1793	}
1794
1795	if (node->type == BTRFS_TREE_BLOCK_REF_KEY ||
1796	node->type == BTRFS_SHARED_BLOCK_REF_KEY)
1797	ret = run_delayed_tree_ref(trans, href, node, extent_op,
1798	insert_reserved);
1799	else if (node->type == BTRFS_EXTENT_DATA_REF_KEY ||
1800	node->type == BTRFS_SHARED_DATA_REF_KEY)
1801	ret = run_delayed_data_ref(trans, href, node, extent_op,
1802	insert_reserved);
1803	else if (node->type == BTRFS_EXTENT_OWNER_REF_KEY)
1804	ret = 0;
1805	else
1806	BUG();
1807	if (ret && insert_reserved)
1808	btrfs_pin_extent(trans, bytenr: node->bytenr, num: node->num_bytes, reserved: 1);
1809	if (ret < 0)
1810	btrfs_err(trans->fs_info,
1811	"failed to run delayed ref for logical %llu num_bytes %llu type %u action %u ref_mod %d: %d",
1812	node->bytenr, node->num_bytes, node->type,
1813	node->action, node->ref_mod, ret);
1814	return ret;
1815	}
1816
1817	static inline struct btrfs_delayed_ref_node *
1818	select_delayed_ref(struct btrfs_delayed_ref_head *head)
1819	{
1820	struct btrfs_delayed_ref_node *ref;
1821
1822	if (RB_EMPTY_ROOT(&head->ref_tree.rb_root))
1823	return NULL;
1824
1825	/*
1826	* Select a delayed ref of type BTRFS_ADD_DELAYED_REF first.
1827	* This is to prevent a ref count from going down to zero, which deletes
1828	* the extent item from the extent tree, when there still are references
1829	* to add, which would fail because they would not find the extent item.
1830	*/
1831	if (!list_empty(head: &head->ref_add_list))
1832	return list_first_entry(&head->ref_add_list,
1833	struct btrfs_delayed_ref_node, add_list);
1834
1835	ref = rb_entry(rb_first_cached(&head->ref_tree),
1836	struct btrfs_delayed_ref_node, ref_node);
1837	ASSERT(list_empty(&ref->add_list));
1838	return ref;
1839	}
1840
1841	static void unselect_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
1842	struct btrfs_delayed_ref_head *head)
1843	{
1844	spin_lock(lock: &delayed_refs->lock);
1845	head->processing = false;
1846	delayed_refs->num_heads_ready++;
1847	spin_unlock(lock: &delayed_refs->lock);
1848	btrfs_delayed_ref_unlock(head);
1849	}
1850
1851	static struct btrfs_delayed_extent_op *cleanup_extent_op(
1852	struct btrfs_delayed_ref_head *head)
1853	{
1854	struct btrfs_delayed_extent_op *extent_op = head->extent_op;
1855
1856	if (!extent_op)
1857	return NULL;
1858
1859	if (head->must_insert_reserved) {
1860	head->extent_op = NULL;
1861	btrfs_free_delayed_extent_op(op: extent_op);
1862	return NULL;
1863	}
1864	return extent_op;
1865	}
1866
1867	static int run_and_cleanup_extent_op(struct btrfs_trans_handle *trans,
1868	struct btrfs_delayed_ref_head *head)
1869	{
1870	struct btrfs_delayed_extent_op *extent_op;
1871	int ret;
1872
1873	extent_op = cleanup_extent_op(head);
1874	if (!extent_op)
1875	return 0;
1876	head->extent_op = NULL;
1877	spin_unlock(lock: &head->lock);
1878	ret = run_delayed_extent_op(trans, head, extent_op);
1879	btrfs_free_delayed_extent_op(op: extent_op);
1880	return ret ? ret : 1;
1881	}
1882
1883	u64 btrfs_cleanup_ref_head_accounting(struct btrfs_fs_info *fs_info,
1884	struct btrfs_delayed_ref_root *delayed_refs,
1885	struct btrfs_delayed_ref_head *head)
1886	{
1887	u64 ret = 0;
1888
1889	/*
1890	* We had csum deletions accounted for in our delayed refs rsv, we need
1891	* to drop the csum leaves for this update from our delayed_refs_rsv.
1892	*/
1893	if (head->total_ref_mod < 0 && head->is_data) {
1894	int nr_csums;
1895
1896	spin_lock(lock: &delayed_refs->lock);
1897	delayed_refs->pending_csums -= head->num_bytes;
1898	spin_unlock(lock: &delayed_refs->lock);
1899	nr_csums = btrfs_csum_bytes_to_leaves(fs_info, csum_bytes: head->num_bytes);
1900
1901	btrfs_delayed_refs_rsv_release(fs_info, nr_refs: 0, nr_csums);
1902
1903	ret = btrfs_calc_delayed_ref_csum_bytes(fs_info, num_csum_items: nr_csums);
1904	}
1905	/* must_insert_reserved can be set only if we didn't run the head ref. */
1906	if (head->must_insert_reserved)
1907	free_head_ref_squota_rsv(fs_info, href: head);
1908
1909	return ret;
1910	}
1911
1912	static int cleanup_ref_head(struct btrfs_trans_handle *trans,
1913	struct btrfs_delayed_ref_head *head,
1914	u64 *bytes_released)
1915	{
1916
1917	struct btrfs_fs_info *fs_info = trans->fs_info;
1918	struct btrfs_delayed_ref_root *delayed_refs;
1919	int ret;
1920
1921	delayed_refs = &trans->transaction->delayed_refs;
1922
1923	ret = run_and_cleanup_extent_op(trans, head);
1924	if (ret < 0) {
1925	unselect_delayed_ref_head(delayed_refs, head);
1926	btrfs_debug(fs_info, "run_delayed_extent_op returned %d", ret);
1927	return ret;
1928	} else if (ret) {
1929	return ret;
1930	}
1931
1932	/*
1933	* Need to drop our head ref lock and re-acquire the delayed ref lock
1934	* and then re-check to make sure nobody got added.
1935	*/
1936	spin_unlock(lock: &head->lock);
1937	spin_lock(lock: &delayed_refs->lock);
1938	spin_lock(lock: &head->lock);
1939	if (!RB_EMPTY_ROOT(&head->ref_tree.rb_root) || head->extent_op) {
1940	spin_unlock(lock: &head->lock);
1941	spin_unlock(lock: &delayed_refs->lock);
1942	return 1;
1943	}
1944	btrfs_delete_ref_head(delayed_refs, head);
1945	spin_unlock(lock: &head->lock);
1946	spin_unlock(lock: &delayed_refs->lock);
1947
1948	if (head->must_insert_reserved) {
1949	btrfs_pin_extent(trans, bytenr: head->bytenr, num: head->num_bytes, reserved: 1);
1950	if (head->is_data) {
1951	struct btrfs_root *csum_root;
1952
1953	csum_root = btrfs_csum_root(fs_info, bytenr: head->bytenr);
1954	ret = btrfs_del_csums(trans, root: csum_root, bytenr: head->bytenr,
1955	len: head->num_bytes);
1956	}
1957	}
1958
1959	*bytes_released += btrfs_cleanup_ref_head_accounting(fs_info, delayed_refs, head);
1960
1961	trace_run_delayed_ref_head(fs_info, head_ref: head, action: 0);
1962	btrfs_delayed_ref_unlock(head);
1963	btrfs_put_delayed_ref_head(head);
1964	return ret;
1965	}
1966
1967	static struct btrfs_delayed_ref_head *btrfs_obtain_ref_head(
1968	struct btrfs_trans_handle *trans)
1969	{
1970	struct btrfs_delayed_ref_root *delayed_refs =
1971	&trans->transaction->delayed_refs;
1972	struct btrfs_delayed_ref_head *head = NULL;
1973	int ret;
1974
1975	spin_lock(lock: &delayed_refs->lock);
1976	head = btrfs_select_ref_head(delayed_refs);
1977	if (!head) {
1978	spin_unlock(lock: &delayed_refs->lock);
1979	return head;
1980	}
1981
1982	/*
1983	* Grab the lock that says we are going to process all the refs for
1984	* this head
1985	*/
1986	ret = btrfs_delayed_ref_lock(delayed_refs, head);
1987	spin_unlock(lock: &delayed_refs->lock);
1988
1989	/*
1990	* We may have dropped the spin lock to get the head mutex lock, and
1991	* that might have given someone else time to free the head. If that's
1992	* true, it has been removed from our list and we can move on.
1993	*/
1994	if (ret == -EAGAIN)
1995	head = ERR_PTR(error: -EAGAIN);
1996
1997	return head;
1998	}
1999
2000	static int btrfs_run_delayed_refs_for_head(struct btrfs_trans_handle *trans,
2001	struct btrfs_delayed_ref_head *locked_ref,
2002	u64 *bytes_released)
2003	{
2004	struct btrfs_fs_info *fs_info = trans->fs_info;
2005	struct btrfs_delayed_ref_root *delayed_refs;
2006	struct btrfs_delayed_extent_op *extent_op;
2007	struct btrfs_delayed_ref_node *ref;
2008	bool must_insert_reserved;
2009	int ret;
2010
2011	delayed_refs = &trans->transaction->delayed_refs;
2012
2013	lockdep_assert_held(&locked_ref->mutex);
2014	lockdep_assert_held(&locked_ref->lock);
2015
2016	while ((ref = select_delayed_ref(head: locked_ref))) {
2017	if (ref->seq &&
2018	btrfs_check_delayed_seq(fs_info, seq: ref->seq)) {
2019	spin_unlock(lock: &locked_ref->lock);
2020	unselect_delayed_ref_head(delayed_refs, head: locked_ref);
2021	return -EAGAIN;
2022	}
2023
2024	rb_erase_cached(node: &ref->ref_node, root: &locked_ref->ref_tree);
2025	RB_CLEAR_NODE(&ref->ref_node);
2026	if (!list_empty(head: &ref->add_list))
2027	list_del(entry: &ref->add_list);
2028	/*
2029	* When we play the delayed ref, also correct the ref_mod on
2030	* head
2031	*/
2032	switch (ref->action) {
2033	case BTRFS_ADD_DELAYED_REF:
2034	case BTRFS_ADD_DELAYED_EXTENT:
2035	locked_ref->ref_mod -= ref->ref_mod;
2036	break;
2037	case BTRFS_DROP_DELAYED_REF:
2038	locked_ref->ref_mod += ref->ref_mod;
2039	break;
2040	default:
2041	WARN_ON(1);
2042	}
2043	atomic_dec(v: &delayed_refs->num_entries);
2044
2045	/*
2046	* Record the must_insert_reserved flag before we drop the
2047	* spin lock.
2048	*/
2049	must_insert_reserved = locked_ref->must_insert_reserved;
2050	/*
2051	* Unsetting this on the head ref relinquishes ownership of
2052	* the rsv_bytes, so it is critical that every possible code
2053	* path from here forward frees all reserves including qgroup
2054	* reserve.
2055	*/
2056	locked_ref->must_insert_reserved = false;
2057
2058	extent_op = locked_ref->extent_op;
2059	locked_ref->extent_op = NULL;
2060	spin_unlock(lock: &locked_ref->lock);
2061
2062	ret = run_one_delayed_ref(trans, href: locked_ref, node: ref, extent_op,
2063	insert_reserved: must_insert_reserved);
2064	btrfs_delayed_refs_rsv_release(fs_info, nr_refs: 1, nr_csums: 0);
2065	*bytes_released += btrfs_calc_delayed_ref_bytes(fs_info, num_delayed_refs: 1);
2066
2067	btrfs_free_delayed_extent_op(op: extent_op);
2068	if (ret) {
2069	unselect_delayed_ref_head(delayed_refs, head: locked_ref);
2070	btrfs_put_delayed_ref(ref);
2071	return ret;
2072	}
2073
2074	btrfs_put_delayed_ref(ref);
2075	cond_resched();
2076
2077	spin_lock(lock: &locked_ref->lock);
2078	btrfs_merge_delayed_refs(fs_info, delayed_refs, head: locked_ref);
2079	}
2080
2081	return 0;
2082	}
2083
2084	/*
2085	* Returns 0 on success or if called with an already aborted transaction.
2086	* Returns -ENOMEM or -EIO on failure and will abort the transaction.
2087	*/
2088	static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
2089	u64 min_bytes)
2090	{
2091	struct btrfs_fs_info *fs_info = trans->fs_info;
2092	struct btrfs_delayed_ref_root *delayed_refs;
2093	struct btrfs_delayed_ref_head *locked_ref = NULL;
2094	int ret;
2095	unsigned long count = 0;
2096	unsigned long max_count = 0;
2097	u64 bytes_processed = 0;
2098
2099	delayed_refs = &trans->transaction->delayed_refs;
2100	if (min_bytes == 0) {
2101	max_count = delayed_refs->num_heads_ready;
2102	min_bytes = U64_MAX;
2103	}
2104
2105	do {
2106	if (!locked_ref) {
2107	locked_ref = btrfs_obtain_ref_head(trans);
2108	if (IS_ERR_OR_NULL(ptr: locked_ref)) {
2109	if (PTR_ERR(ptr: locked_ref) == -EAGAIN) {
2110	continue;
2111	} else {
2112	break;
2113	}
2114	}
2115	count++;
2116	}
2117	/*
2118	* We need to try and merge add/drops of the same ref since we
2119	* can run into issues with relocate dropping the implicit ref
2120	* and then it being added back again before the drop can
2121	* finish. If we merged anything we need to re-loop so we can
2122	* get a good ref.
2123	* Or we can get node references of the same type that weren't
2124	* merged when created due to bumps in the tree mod seq, and
2125	* we need to merge them to prevent adding an inline extent
2126	* backref before dropping it (triggering a BUG_ON at
2127	* insert_inline_extent_backref()).
2128	*/
2129	spin_lock(lock: &locked_ref->lock);
2130	btrfs_merge_delayed_refs(fs_info, delayed_refs, head: locked_ref);
2131
2132	ret = btrfs_run_delayed_refs_for_head(trans, locked_ref, bytes_released: &bytes_processed);
2133	if (ret < 0 && ret != -EAGAIN) {
2134	/*
2135	* Error, btrfs_run_delayed_refs_for_head already
2136	* unlocked everything so just bail out
2137	*/
2138	return ret;
2139	} else if (!ret) {
2140	/*
2141	* Success, perform the usual cleanup of a processed
2142	* head
2143	*/
2144	ret = cleanup_ref_head(trans, head: locked_ref, bytes_released: &bytes_processed);
2145	if (ret > 0 ) {
2146	/* We dropped our lock, we need to loop. */
2147	ret = 0;
2148	continue;
2149	} else if (ret) {
2150	return ret;
2151	}
2152	}
2153
2154	/*
2155	* Either success case or btrfs_run_delayed_refs_for_head
2156	* returned -EAGAIN, meaning we need to select another head
2157	*/
2158
2159	locked_ref = NULL;
2160	cond_resched();
2161	} while ((min_bytes != U64_MAX && bytes_processed < min_bytes) ||
2162	(max_count > 0 && count < max_count) ||
2163	locked_ref);
2164
2165	return 0;
2166	}
2167
2168	#ifdef SCRAMBLE_DELAYED_REFS
2169	/*
2170	* Normally delayed refs get processed in ascending bytenr order. This
2171	* correlates in most cases to the order added. To expose dependencies on this
2172	* order, we start to process the tree in the middle instead of the beginning
2173	*/
2174	static u64 find_middle(struct rb_root *root)
2175	{
2176	struct rb_node *n = root->rb_node;
2177	struct btrfs_delayed_ref_node *entry;
2178	int alt = 1;
2179	u64 middle;
2180	u64 first = 0, last = 0;
2181
2182	n = rb_first(root);
2183	if (n) {
2184	entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
2185	first = entry->bytenr;
2186	}
2187	n = rb_last(root);
2188	if (n) {
2189	entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
2190	last = entry->bytenr;
2191	}
2192	n = root->rb_node;
2193
2194	while (n) {
2195	entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
2196	WARN_ON(!entry->in_tree);
2197
2198	middle = entry->bytenr;
2199
2200	if (alt)
2201	n = n->rb_left;
2202	else
2203	n = n->rb_right;
2204
2205	alt = 1 - alt;
2206	}
2207	return middle;
2208	}
2209	#endif
2210
2211	/*
2212	* Start processing the delayed reference count updates and extent insertions
2213	* we have queued up so far.
2214	*
2215	* @trans: Transaction handle.
2216	* @min_bytes: How many bytes of delayed references to process. After this
2217	* many bytes we stop processing delayed references if there are
2218	* any more. If 0 it means to run all existing delayed references,
2219	* but not new ones added after running all existing ones.
2220	* Use (u64)-1 (U64_MAX) to run all existing delayed references
2221	* plus any new ones that are added.
2222	*
2223	* Returns 0 on success or if called with an aborted transaction
2224	* Returns <0 on error and aborts the transaction
2225	*/
2226	int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, u64 min_bytes)
2227	{
2228	struct btrfs_fs_info *fs_info = trans->fs_info;
2229	struct btrfs_delayed_ref_root *delayed_refs;
2230	int ret;
2231
2232	/* We'll clean this up in btrfs_cleanup_transaction */
2233	if (TRANS_ABORTED(trans))
2234	return 0;
2235
2236	if (test_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags))
2237	return 0;
2238
2239	delayed_refs = &trans->transaction->delayed_refs;
2240	again:
2241	#ifdef SCRAMBLE_DELAYED_REFS
2242	delayed_refs->run_delayed_start = find_middle(&delayed_refs->root);
2243	#endif
2244	ret = __btrfs_run_delayed_refs(trans, min_bytes);
2245	if (ret < 0) {
2246	btrfs_abort_transaction(trans, ret);
2247	return ret;
2248	}
2249
2250	if (min_bytes == U64_MAX) {
2251	btrfs_create_pending_block_groups(trans);
2252
2253	spin_lock(lock: &delayed_refs->lock);
2254	if (RB_EMPTY_ROOT(&delayed_refs->href_root.rb_root)) {
2255	spin_unlock(lock: &delayed_refs->lock);
2256	return 0;
2257	}
2258	spin_unlock(lock: &delayed_refs->lock);
2259
2260	cond_resched();
2261	goto again;
2262	}
2263
2264	return 0;
2265	}
2266
2267	int btrfs_set_disk_extent_flags(struct btrfs_trans_handle *trans,
2268	struct extent_buffer *eb, u64 flags)
2269	{
2270	struct btrfs_delayed_extent_op *extent_op;
2271	int level = btrfs_header_level(eb);
2272	int ret;
2273
2274	extent_op = btrfs_alloc_delayed_extent_op();
2275	if (!extent_op)
2276	return -ENOMEM;
2277
2278	extent_op->flags_to_set = flags;
2279	extent_op->update_flags = true;
2280	extent_op->update_key = false;
2281	extent_op->level = level;
2282
2283	ret = btrfs_add_delayed_extent_op(trans, bytenr: eb->start, num_bytes: eb->len, extent_op);
2284	if (ret)
2285	btrfs_free_delayed_extent_op(op: extent_op);
2286	return ret;
2287	}
2288
2289	static noinline int check_delayed_ref(struct btrfs_root *root,
2290	struct btrfs_path *path,
2291	u64 objectid, u64 offset, u64 bytenr)
2292	{
2293	struct btrfs_delayed_ref_head *head;
2294	struct btrfs_delayed_ref_node *ref;
2295	struct btrfs_delayed_data_ref *data_ref;
2296	struct btrfs_delayed_ref_root *delayed_refs;
2297	struct btrfs_transaction *cur_trans;
2298	struct rb_node *node;
2299	int ret = 0;
2300
2301	spin_lock(lock: &root->fs_info->trans_lock);
2302	cur_trans = root->fs_info->running_transaction;
2303	if (cur_trans)
2304	refcount_inc(r: &cur_trans->use_count);
2305	spin_unlock(lock: &root->fs_info->trans_lock);
2306	if (!cur_trans)
2307	return 0;
2308
2309	delayed_refs = &cur_trans->delayed_refs;
2310	spin_lock(lock: &delayed_refs->lock);
2311	head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
2312	if (!head) {
2313	spin_unlock(lock: &delayed_refs->lock);
2314	btrfs_put_transaction(transaction: cur_trans);
2315	return 0;
2316	}
2317
2318	if (!mutex_trylock(lock: &head->mutex)) {
2319	if (path->nowait) {
2320	spin_unlock(lock: &delayed_refs->lock);
2321	btrfs_put_transaction(transaction: cur_trans);
2322	return -EAGAIN;
2323	}
2324
2325	refcount_inc(r: &head->refs);
2326	spin_unlock(lock: &delayed_refs->lock);
2327
2328	btrfs_release_path(p: path);
2329
2330	/*
2331	* Mutex was contended, block until it's released and let
2332	* caller try again
2333	*/
2334	mutex_lock(&head->mutex);
2335	mutex_unlock(lock: &head->mutex);
2336	btrfs_put_delayed_ref_head(head);
2337	btrfs_put_transaction(transaction: cur_trans);
2338	return -EAGAIN;
2339	}
2340	spin_unlock(lock: &delayed_refs->lock);
2341
2342	spin_lock(lock: &head->lock);
2343	/*
2344	* XXX: We should replace this with a proper search function in the
2345	* future.
2346	*/
2347	for (node = rb_first_cached(&head->ref_tree); node;
2348	node = rb_next(node)) {
2349	ref = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
2350	/* If it's a shared ref we know a cross reference exists */
2351	if (ref->type != BTRFS_EXTENT_DATA_REF_KEY) {
2352	ret = 1;
2353	break;
2354	}
2355
2356	data_ref = btrfs_delayed_node_to_data_ref(node: ref);
2357
2358	/*
2359	* If our ref doesn't match the one we're currently looking at
2360	* then we have a cross reference.
2361	*/
2362	if (data_ref->root != root->root_key.objectid ||
2363	data_ref->objectid != objectid ||
2364	data_ref->offset != offset) {
2365	ret = 1;
2366	break;
2367	}
2368	}
2369	spin_unlock(lock: &head->lock);
2370	mutex_unlock(lock: &head->mutex);
2371	btrfs_put_transaction(transaction: cur_trans);
2372	return ret;
2373	}
2374
2375	static noinline int check_committed_ref(struct btrfs_root *root,
2376	struct btrfs_path *path,
2377	u64 objectid, u64 offset, u64 bytenr,
2378	bool strict)
2379	{
2380	struct btrfs_fs_info *fs_info = root->fs_info;
2381	struct btrfs_root *extent_root = btrfs_extent_root(fs_info, bytenr);
2382	struct extent_buffer *leaf;
2383	struct btrfs_extent_data_ref *ref;
2384	struct btrfs_extent_inline_ref *iref;
2385	struct btrfs_extent_item *ei;
2386	struct btrfs_key key;
2387	u32 item_size;
2388	u32 expected_size;
2389	int type;
2390	int ret;
2391
2392	key.objectid = bytenr;
2393	key.offset = (u64)-1;
2394	key.type = BTRFS_EXTENT_ITEM_KEY;
2395
2396	ret = btrfs_search_slot(NULL, root: extent_root, key: &key, p: path, ins_len: 0, cow: 0);
2397	if (ret < 0)
2398	goto out;
2399	if (ret == 0) {
2400	/*
2401	* Key with offset -1 found, there would have to exist an extent
2402	* item with such offset, but this is out of the valid range.
2403	*/
2404	ret = -EUCLEAN;
2405	goto out;
2406	}
2407
2408	ret = -ENOENT;
2409	if (path->slots[0] == 0)
2410	goto out;
2411
2412	path->slots[0]--;
2413	leaf = path->nodes[0];
2414	btrfs_item_key_to_cpu(eb: leaf, cpu_key: &key, nr: path->slots[0]);
2415
2416	if (key.objectid != bytenr || key.type != BTRFS_EXTENT_ITEM_KEY)
2417	goto out;
2418
2419	ret = 1;
2420	item_size = btrfs_item_size(eb: leaf, slot: path->slots[0]);
2421	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
2422	expected_size = sizeof(*ei) + btrfs_extent_inline_ref_size(BTRFS_EXTENT_DATA_REF_KEY);
2423
2424	/* No inline refs; we need to bail before checking for owner ref. */
2425	if (item_size == sizeof(*ei))
2426	goto out;
2427
2428	/* Check for an owner ref; skip over it to the real inline refs. */
2429	iref = (struct btrfs_extent_inline_ref *)(ei + 1);
2430	type = btrfs_get_extent_inline_ref_type(eb: leaf, iref, is_data: BTRFS_REF_TYPE_DATA);
2431	if (btrfs_fs_incompat(fs_info, SIMPLE_QUOTA) && type == BTRFS_EXTENT_OWNER_REF_KEY) {
2432	expected_size += btrfs_extent_inline_ref_size(BTRFS_EXTENT_OWNER_REF_KEY);
2433	iref = (struct btrfs_extent_inline_ref *)(iref + 1);
2434	}
2435
2436	/* If extent item has more than 1 inline ref then it's shared */
2437	if (item_size != expected_size)
2438	goto out;
2439
2440	/*
2441	* If extent created before last snapshot => it's shared unless the
2442	* snapshot has been deleted. Use the heuristic if strict is false.
2443	*/
2444	if (!strict &&
2445	(btrfs_extent_generation(eb: leaf, s: ei) <=
2446	btrfs_root_last_snapshot(s: &root->root_item)))
2447	goto out;
2448
2449	/* If this extent has SHARED_DATA_REF then it's shared */
2450	type = btrfs_get_extent_inline_ref_type(eb: leaf, iref, is_data: BTRFS_REF_TYPE_DATA);
2451	if (type != BTRFS_EXTENT_DATA_REF_KEY)
2452	goto out;
2453
2454	ref = (struct btrfs_extent_data_ref *)(&iref->offset);
2455	if (btrfs_extent_refs(eb: leaf, s: ei) !=
2456	btrfs_extent_data_ref_count(eb: leaf, s: ref) ||
2457	btrfs_extent_data_ref_root(eb: leaf, s: ref) !=
2458	root->root_key.objectid ||
2459	btrfs_extent_data_ref_objectid(eb: leaf, s: ref) != objectid ||
2460	btrfs_extent_data_ref_offset(eb: leaf, s: ref) != offset)
2461	goto out;
2462
2463	ret = 0;
2464	out:
2465	return ret;
2466	}
2467
2468	int btrfs_cross_ref_exist(struct btrfs_root *root, u64 objectid, u64 offset,
2469	u64 bytenr, bool strict, struct btrfs_path *path)
2470	{
2471	int ret;
2472
2473	do {
2474	ret = check_committed_ref(root, path, objectid,
2475	offset, bytenr, strict);
2476	if (ret && ret != -ENOENT)
2477	goto out;
2478
2479	ret = check_delayed_ref(root, path, objectid, offset, bytenr);
2480	} while (ret == -EAGAIN);
2481
2482	out:
2483	btrfs_release_path(p: path);
2484	if (btrfs_is_data_reloc_root(root))
2485	WARN_ON(ret > 0);
2486	return ret;
2487	}
2488
2489	static int __btrfs_mod_ref(struct btrfs_trans_handle *trans,
2490	struct btrfs_root *root,
2491	struct extent_buffer *buf,
2492	int full_backref, int inc)
2493	{
2494	struct btrfs_fs_info *fs_info = root->fs_info;
2495	u64 bytenr;
2496	u64 num_bytes;
2497	u64 parent;
2498	u64 ref_root;
2499	u32 nritems;
2500	struct btrfs_key key;
2501	struct btrfs_file_extent_item *fi;
2502	struct btrfs_ref generic_ref = { 0 };
2503	bool for_reloc = btrfs_header_flag(eb: buf, BTRFS_HEADER_FLAG_RELOC);
2504	int i;
2505	int action;
2506	int level;
2507	int ret = 0;
2508
2509	if (btrfs_is_testing(fs_info))
2510	return 0;
2511
2512	ref_root = btrfs_header_owner(eb: buf);
2513	nritems = btrfs_header_nritems(eb: buf);
2514	level = btrfs_header_level(eb: buf);
2515
2516	if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state) && level == 0)
2517	return 0;
2518
2519	if (full_backref)
2520	parent = buf->start;
2521	else
2522	parent = 0;
2523	if (inc)
2524	action = BTRFS_ADD_DELAYED_REF;
2525	else
2526	action = BTRFS_DROP_DELAYED_REF;
2527
2528	for (i = 0; i < nritems; i++) {
2529	if (level == 0) {
2530	btrfs_item_key_to_cpu(eb: buf, cpu_key: &key, nr: i);
2531	if (key.type != BTRFS_EXTENT_DATA_KEY)
2532	continue;
2533	fi = btrfs_item_ptr(buf, i,
2534	struct btrfs_file_extent_item);
2535	if (btrfs_file_extent_type(eb: buf, s: fi) ==
2536	BTRFS_FILE_EXTENT_INLINE)
2537	continue;
2538	bytenr = btrfs_file_extent_disk_bytenr(eb: buf, s: fi);
2539	if (bytenr == 0)
2540	continue;
2541
2542	num_bytes = btrfs_file_extent_disk_num_bytes(eb: buf, s: fi);
2543	key.offset -= btrfs_file_extent_offset(eb: buf, s: fi);
2544	btrfs_init_generic_ref(generic_ref: &generic_ref, action, bytenr,
2545	len: num_bytes, parent, owning_root: ref_root);
2546	btrfs_init_data_ref(generic_ref: &generic_ref, ref_root, ino: key.objectid,
2547	offset: key.offset, mod_root: root->root_key.objectid,
2548	skip_qgroup: for_reloc);
2549	if (inc)
2550	ret = btrfs_inc_extent_ref(trans, generic_ref: &generic_ref);
2551	else
2552	ret = btrfs_free_extent(trans, ref: &generic_ref);
2553	if (ret)
2554	goto fail;
2555	} else {
2556	bytenr = btrfs_node_blockptr(eb: buf, nr: i);
2557	num_bytes = fs_info->nodesize;
2558	/* We don't know the owning_root, use 0. */
2559	btrfs_init_generic_ref(generic_ref: &generic_ref, action, bytenr,
2560	len: num_bytes, parent, owning_root: 0);
2561	btrfs_init_tree_ref(generic_ref: &generic_ref, level: level - 1, root: ref_root,
2562	mod_root: root->root_key.objectid, skip_qgroup: for_reloc);
2563	if (inc)
2564	ret = btrfs_inc_extent_ref(trans, generic_ref: &generic_ref);
2565	else
2566	ret = btrfs_free_extent(trans, ref: &generic_ref);
2567	if (ret)
2568	goto fail;
2569	}
2570	}
2571	return 0;
2572	fail:
2573	return ret;
2574	}
2575
2576	int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2577	struct extent_buffer *buf, int full_backref)
2578	{
2579	return __btrfs_mod_ref(trans, root, buf, full_backref, inc: 1);
2580	}
2581
2582	int btrfs_dec_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2583	struct extent_buffer *buf, int full_backref)
2584	{
2585	return __btrfs_mod_ref(trans, root, buf, full_backref, inc: 0);
2586	}
2587
2588	static u64 get_alloc_profile_by_root(struct btrfs_root *root, int data)
2589	{
2590	struct btrfs_fs_info *fs_info = root->fs_info;
2591	u64 flags;
2592	u64 ret;
2593
2594	if (data)
2595	flags = BTRFS_BLOCK_GROUP_DATA;
2596	else if (root == fs_info->chunk_root)
2597	flags = BTRFS_BLOCK_GROUP_SYSTEM;
2598	else
2599	flags = BTRFS_BLOCK_GROUP_METADATA;
2600
2601	ret = btrfs_get_alloc_profile(fs_info, orig_flags: flags);
2602	return ret;
2603	}
2604
2605	static u64 first_logical_byte(struct btrfs_fs_info *fs_info)
2606	{
2607	struct rb_node *leftmost;
2608	u64 bytenr = 0;
2609
2610	read_lock(&fs_info->block_group_cache_lock);
2611	/* Get the block group with the lowest logical start address. */
2612	leftmost = rb_first_cached(&fs_info->block_group_cache_tree);
2613	if (leftmost) {
2614	struct btrfs_block_group *bg;
2615
2616	bg = rb_entry(leftmost, struct btrfs_block_group, cache_node);
2617	bytenr = bg->start;
2618	}
2619	read_unlock(&fs_info->block_group_cache_lock);
2620
2621	return bytenr;
2622	}
2623
2624	static int pin_down_extent(struct btrfs_trans_handle *trans,
2625	struct btrfs_block_group *cache,
2626	u64 bytenr, u64 num_bytes, int reserved)
2627	{
2628	struct btrfs_fs_info *fs_info = cache->fs_info;
2629
2630	spin_lock(lock: &cache->space_info->lock);
2631	spin_lock(lock: &cache->lock);
2632	cache->pinned += num_bytes;
2633	btrfs_space_info_update_bytes_pinned(fs_info, sinfo: cache->space_info,
2634	bytes: num_bytes);
2635	if (reserved) {
2636	cache->reserved -= num_bytes;
2637	cache->space_info->bytes_reserved -= num_bytes;
2638	}
2639	spin_unlock(lock: &cache->lock);
2640	spin_unlock(lock: &cache->space_info->lock);
2641
2642	set_extent_bit(tree: &trans->transaction->pinned_extents, start: bytenr,
2643	end: bytenr + num_bytes - 1, bits: EXTENT_DIRTY, NULL);
2644	return 0;
2645	}
2646
2647	int btrfs_pin_extent(struct btrfs_trans_handle *trans,
2648	u64 bytenr, u64 num_bytes, int reserved)
2649	{
2650	struct btrfs_block_group *cache;
2651
2652	cache = btrfs_lookup_block_group(info: trans->fs_info, bytenr);
2653	BUG_ON(!cache); /* Logic error */
2654
2655	pin_down_extent(trans, cache, bytenr, num_bytes, reserved);
2656
2657	btrfs_put_block_group(cache);
2658	return 0;
2659	}
2660
2661	int btrfs_pin_extent_for_log_replay(struct btrfs_trans_handle *trans,
2662	const struct extent_buffer *eb)
2663	{
2664	struct btrfs_block_group *cache;
2665	int ret;
2666
2667	cache = btrfs_lookup_block_group(info: trans->fs_info, bytenr: eb->start);
2668	if (!cache)
2669	return -EINVAL;
2670
2671	/*
2672	* Fully cache the free space first so that our pin removes the free space
2673	* from the cache.
2674	*/
2675	ret = btrfs_cache_block_group(cache, wait: true);
2676	if (ret)
2677	goto out;
2678
2679	pin_down_extent(trans, cache, bytenr: eb->start, num_bytes: eb->len, reserved: 0);
2680
2681	/* remove us from the free space cache (if we're there at all) */
2682	ret = btrfs_remove_free_space(block_group: cache, bytenr: eb->start, size: eb->len);
2683	out:
2684	btrfs_put_block_group(cache);
2685	return ret;
2686	}
2687
2688	static int __exclude_logged_extent(struct btrfs_fs_info *fs_info,
2689	u64 start, u64 num_bytes)
2690	{
2691	int ret;
2692	struct btrfs_block_group *block_group;
2693
2694	block_group = btrfs_lookup_block_group(info: fs_info, bytenr: start);
2695	if (!block_group)
2696	return -EINVAL;
2697
2698	ret = btrfs_cache_block_group(cache: block_group, wait: true);
2699	if (ret)
2700	goto out;
2701
2702	ret = btrfs_remove_free_space(block_group, bytenr: start, size: num_bytes);
2703	out:
2704	btrfs_put_block_group(cache: block_group);
2705	return ret;
2706	}
2707
2708	int btrfs_exclude_logged_extents(struct extent_buffer *eb)
2709	{
2710	struct btrfs_fs_info *fs_info = eb->fs_info;
2711	struct btrfs_file_extent_item *item;
2712	struct btrfs_key key;
2713	int found_type;
2714	int i;
2715	int ret = 0;
2716
2717	if (!btrfs_fs_incompat(fs_info, MIXED_GROUPS))
2718	return 0;
2719
2720	for (i = 0; i < btrfs_header_nritems(eb); i++) {
2721	btrfs_item_key_to_cpu(eb, cpu_key: &key, nr: i);
2722	if (key.type != BTRFS_EXTENT_DATA_KEY)
2723	continue;
2724	item = btrfs_item_ptr(eb, i, struct btrfs_file_extent_item);
2725	found_type = btrfs_file_extent_type(eb, s: item);
2726	if (found_type == BTRFS_FILE_EXTENT_INLINE)
2727	continue;
2728	if (btrfs_file_extent_disk_bytenr(eb, s: item) == 0)
2729	continue;
2730	key.objectid = btrfs_file_extent_disk_bytenr(eb, s: item);
2731	key.offset = btrfs_file_extent_disk_num_bytes(eb, s: item);
2732	ret = __exclude_logged_extent(fs_info, start: key.objectid, num_bytes: key.offset);
2733	if (ret)
2734	break;
2735	}
2736
2737	return ret;
2738	}
2739
2740	static void
2741	btrfs_inc_block_group_reservations(struct btrfs_block_group *bg)
2742	{
2743	atomic_inc(v: &bg->reservations);
2744	}
2745
2746	/*
2747	* Returns the free cluster for the given space info and sets empty_cluster to
2748	* what it should be based on the mount options.
2749	*/
2750	static struct btrfs_free_cluster *
2751	fetch_cluster_info(struct btrfs_fs_info *fs_info,
2752	struct btrfs_space_info *space_info, u64 *empty_cluster)
2753	{
2754	struct btrfs_free_cluster *ret = NULL;
2755
2756	*empty_cluster = 0;
2757	if (btrfs_mixed_space_info(space_info))
2758	return ret;
2759
2760	if (space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
2761	ret = &fs_info->meta_alloc_cluster;
2762	if (btrfs_test_opt(fs_info, SSD))
2763	*empty_cluster = SZ_2M;
2764	else
2765	*empty_cluster = SZ_64K;
2766	} else if ((space_info->flags & BTRFS_BLOCK_GROUP_DATA) &&
2767	btrfs_test_opt(fs_info, SSD_SPREAD)) {
2768	*empty_cluster = SZ_2M;
2769	ret = &fs_info->data_alloc_cluster;
2770	}
2771
2772	return ret;
2773	}
2774
2775	static int unpin_extent_range(struct btrfs_fs_info *fs_info,
2776	u64 start, u64 end,
2777	const bool return_free_space)
2778	{
2779	struct btrfs_block_group *cache = NULL;
2780	struct btrfs_space_info *space_info;
2781	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
2782	struct btrfs_free_cluster *cluster = NULL;
2783	u64 len;
2784	u64 total_unpinned = 0;
2785	u64 empty_cluster = 0;
2786	bool readonly;
2787	int ret = 0;
2788
2789	while (start <= end) {
2790	readonly = false;
2791	if (!cache ||
2792	start >= cache->start + cache->length) {
2793	if (cache)
2794	btrfs_put_block_group(cache);
2795	total_unpinned = 0;
2796	cache = btrfs_lookup_block_group(info: fs_info, bytenr: start);
2797	if (cache == NULL) {
2798	/* Logic error, something removed the block group. */
2799	ret = -EUCLEAN;
2800	goto out;
2801	}
2802
2803	cluster = fetch_cluster_info(fs_info,
2804	space_info: cache->space_info,
2805	empty_cluster: &empty_cluster);
2806	empty_cluster <<= 1;
2807	}
2808
2809	len = cache->start + cache->length - start;
2810	len = min(len, end + 1 - start);
2811
2812	if (return_free_space)
2813	btrfs_add_free_space(block_group: cache, bytenr: start, size: len);
2814
2815	start += len;
2816	total_unpinned += len;
2817	space_info = cache->space_info;
2818
2819	/*
2820	* If this space cluster has been marked as fragmented and we've
2821	* unpinned enough in this block group to potentially allow a
2822	* cluster to be created inside of it go ahead and clear the
2823	* fragmented check.
2824	*/
2825	if (cluster && cluster->fragmented &&
2826	total_unpinned > empty_cluster) {
2827	spin_lock(lock: &cluster->lock);
2828	cluster->fragmented = 0;
2829	spin_unlock(lock: &cluster->lock);
2830	}
2831
2832	spin_lock(lock: &space_info->lock);
2833	spin_lock(lock: &cache->lock);
2834	cache->pinned -= len;
2835	btrfs_space_info_update_bytes_pinned(fs_info, sinfo: space_info, bytes: -len);
2836	space_info->max_extent_size = 0;
2837	if (cache->ro) {
2838	space_info->bytes_readonly += len;
2839	readonly = true;
2840	} else if (btrfs_is_zoned(fs_info)) {
2841	/* Need reset before reusing in a zoned block group */
2842	space_info->bytes_zone_unusable += len;
2843	readonly = true;
2844	}
2845	spin_unlock(lock: &cache->lock);
2846	if (!readonly && return_free_space &&
2847	global_rsv->space_info == space_info) {
2848	spin_lock(lock: &global_rsv->lock);
2849	if (!global_rsv->full) {
2850	u64 to_add = min(len, global_rsv->size -
2851	global_rsv->reserved);
2852
2853	global_rsv->reserved += to_add;
2854	btrfs_space_info_update_bytes_may_use(fs_info,
2855	sinfo: space_info, bytes: to_add);
2856	if (global_rsv->reserved >= global_rsv->size)
2857	global_rsv->full = 1;
2858	len -= to_add;
2859	}
2860	spin_unlock(lock: &global_rsv->lock);
2861	}
2862	/* Add to any tickets we may have */
2863	if (!readonly && return_free_space && len)
2864	btrfs_try_granting_tickets(fs_info, space_info);
2865	spin_unlock(lock: &space_info->lock);
2866	}
2867
2868	if (cache)
2869	btrfs_put_block_group(cache);
2870	out:
2871	return ret;
2872	}
2873
2874	int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans)
2875	{
2876	struct btrfs_fs_info *fs_info = trans->fs_info;
2877	struct btrfs_block_group *block_group, *tmp;
2878	struct list_head *deleted_bgs;
2879	struct extent_io_tree *unpin;
2880	u64 start;
2881	u64 end;
2882	int ret;
2883
2884	unpin = &trans->transaction->pinned_extents;
2885
2886	while (!TRANS_ABORTED(trans)) {
2887	struct extent_state *cached_state = NULL;
2888
2889	mutex_lock(&fs_info->unused_bg_unpin_mutex);
2890	if (!find_first_extent_bit(tree: unpin, start: 0, start_ret: &start, end_ret: &end,
2891	bits: EXTENT_DIRTY, cached_state: &cached_state)) {
2892	mutex_unlock(lock: &fs_info->unused_bg_unpin_mutex);
2893	break;
2894	}
2895
2896	if (btrfs_test_opt(fs_info, DISCARD_SYNC))
2897	ret = btrfs_discard_extent(fs_info, bytenr: start,
2898	num_bytes: end + 1 - start, NULL);
2899
2900	clear_extent_dirty(tree: unpin, start, end, cached: &cached_state);
2901	ret = unpin_extent_range(fs_info, start, end, return_free_space: true);
2902	BUG_ON(ret);
2903	mutex_unlock(lock: &fs_info->unused_bg_unpin_mutex);
2904	free_extent_state(state: cached_state);
2905	cond_resched();
2906	}
2907
2908	if (btrfs_test_opt(fs_info, DISCARD_ASYNC)) {
2909	btrfs_discard_calc_delay(discard_ctl: &fs_info->discard_ctl);
2910	btrfs_discard_schedule_work(discard_ctl: &fs_info->discard_ctl, override: true);
2911	}
2912
2913	/*
2914	* Transaction is finished. We don't need the lock anymore. We
2915	* do need to clean up the block groups in case of a transaction
2916	* abort.
2917	*/
2918	deleted_bgs = &trans->transaction->deleted_bgs;
2919	list_for_each_entry_safe(block_group, tmp, deleted_bgs, bg_list) {
2920	u64 trimmed = 0;
2921
2922	ret = -EROFS;
2923	if (!TRANS_ABORTED(trans))
2924	ret = btrfs_discard_extent(fs_info,
2925	bytenr: block_group->start,
2926	num_bytes: block_group->length,
2927	actual_bytes: &trimmed);
2928
2929	list_del_init(entry: &block_group->bg_list);
2930	btrfs_unfreeze_block_group(cache: block_group);
2931	btrfs_put_block_group(cache: block_group);
2932
2933	if (ret) {
2934	const char *errstr = btrfs_decode_error(error: ret);
2935	btrfs_warn(fs_info,
2936	"discard failed while removing blockgroup: errno=%d %s",
2937	ret, errstr);
2938	}
2939	}
2940
2941	return 0;
2942	}
2943
2944	/*
2945	* Parse an extent item's inline extents looking for a simple quotas owner ref.
2946	*
2947	* @fs_info: the btrfs_fs_info for this mount
2948	* @leaf: a leaf in the extent tree containing the extent item
2949	* @slot: the slot in the leaf where the extent item is found
2950	*
2951	* Returns the objectid of the root that originally allocated the extent item
2952	* if the inline owner ref is expected and present, otherwise 0.
2953	*
2954	* If an extent item has an owner ref item, it will be the first inline ref
2955	* item. Therefore the logic is to check whether there are any inline ref
2956	* items, then check the type of the first one.
2957	*/
2958	u64 btrfs_get_extent_owner_root(struct btrfs_fs_info *fs_info,
2959	struct extent_buffer *leaf, int slot)
2960	{
2961	struct btrfs_extent_item *ei;
2962	struct btrfs_extent_inline_ref *iref;
2963	struct btrfs_extent_owner_ref *oref;
2964	unsigned long ptr;
2965	unsigned long end;
2966	int type;
2967
2968	if (!btrfs_fs_incompat(fs_info, SIMPLE_QUOTA))
2969	return 0;
2970
2971	ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
2972	ptr = (unsigned long)(ei + 1);
2973	end = (unsigned long)ei + btrfs_item_size(eb: leaf, slot);
2974
2975	/* No inline ref items of any kind, can't check type. */
2976	if (ptr == end)
2977	return 0;
2978
2979	iref = (struct btrfs_extent_inline_ref *)ptr;
2980	type = btrfs_get_extent_inline_ref_type(eb: leaf, iref, is_data: BTRFS_REF_TYPE_ANY);
2981
2982	/* We found an owner ref, get the root out of it. */
2983	if (type == BTRFS_EXTENT_OWNER_REF_KEY) {
2984	oref = (struct btrfs_extent_owner_ref *)(&iref->offset);
2985	return btrfs_extent_owner_ref_root_id(eb: leaf, s: oref);
2986	}
2987
2988	/* We have inline refs, but not an owner ref. */
2989	return 0;
2990	}
2991
2992	static int do_free_extent_accounting(struct btrfs_trans_handle *trans,
2993	u64 bytenr, struct btrfs_squota_delta *delta)
2994	{
2995	int ret;
2996	u64 num_bytes = delta->num_bytes;
2997
2998	if (delta->is_data) {
2999	struct btrfs_root *csum_root;
3000
3001	csum_root = btrfs_csum_root(fs_info: trans->fs_info, bytenr);
3002	ret = btrfs_del_csums(trans, root: csum_root, bytenr, len: num_bytes);
3003	if (ret) {
3004	btrfs_abort_transaction(trans, ret);
3005	return ret;
3006	}
3007
3008	ret = btrfs_delete_raid_extent(trans, start: bytenr, length: num_bytes);
3009	if (ret) {
3010	btrfs_abort_transaction(trans, ret);
3011	return ret;
3012	}
3013	}
3014
3015	ret = btrfs_record_squota_delta(fs_info: trans->fs_info, delta);
3016	if (ret) {
3017	btrfs_abort_transaction(trans, ret);
3018	return ret;
3019	}
3020
3021	ret = add_to_free_space_tree(trans, start: bytenr, size: num_bytes);
3022	if (ret) {
3023	btrfs_abort_transaction(trans, ret);
3024	return ret;
3025	}
3026
3027	ret = btrfs_update_block_group(trans, bytenr, num_bytes, alloc: false);
3028	if (ret)
3029	btrfs_abort_transaction(trans, ret);
3030
3031	return ret;
3032	}
3033
3034	#define abort_and_dump(trans, path, fmt, args...) \
3035	({ \
3036	btrfs_abort_transaction(trans, -EUCLEAN); \
3037	btrfs_print_leaf(path->nodes[0]); \
3038	btrfs_crit(trans->fs_info, fmt, ##args); \
3039	})
3040
3041	/*
3042	* Drop one or more refs of @node.
3043	*
3044	* 1. Locate the extent refs.
3045	* It's either inline in EXTENT/METADATA_ITEM or in keyed SHARED_* item.
3046	* Locate it, then reduce the refs number or remove the ref line completely.
3047	*
3048	* 2. Update the refs count in EXTENT/METADATA_ITEM
3049	*
3050	* Inline backref case:
3051	*
3052	* in extent tree we have:
3053	*
3054	* item 0 key (13631488 EXTENT_ITEM 1048576) itemoff 16201 itemsize 82
3055	* refs 2 gen 6 flags DATA
3056	* extent data backref root FS_TREE objectid 258 offset 0 count 1
3057	* extent data backref root FS_TREE objectid 257 offset 0 count 1
3058	*
3059	* This function gets called with:
3060	*
3061	* node->bytenr = 13631488
3062	* node->num_bytes = 1048576
3063	* root_objectid = FS_TREE
3064	* owner_objectid = 257
3065	* owner_offset = 0
3066	* refs_to_drop = 1
3067	*
3068	* Then we should get some like:
3069	*
3070	* item 0 key (13631488 EXTENT_ITEM 1048576) itemoff 16201 itemsize 82
3071	* refs 1 gen 6 flags DATA
3072	* extent data backref root FS_TREE objectid 258 offset 0 count 1
3073	*
3074	* Keyed backref case:
3075	*
3076	* in extent tree we have:
3077	*
3078	* item 0 key (13631488 EXTENT_ITEM 1048576) itemoff 3971 itemsize 24
3079	* refs 754 gen 6 flags DATA
3080	* [...]
3081	* item 2 key (13631488 EXTENT_DATA_REF <HASH>) itemoff 3915 itemsize 28
3082	* extent data backref root FS_TREE objectid 866 offset 0 count 1
3083	*
3084	* This function get called with:
3085	*
3086	* node->bytenr = 13631488
3087	* node->num_bytes = 1048576
3088	* root_objectid = FS_TREE
3089	* owner_objectid = 866
3090	* owner_offset = 0
3091	* refs_to_drop = 1
3092	*
3093	* Then we should get some like:
3094	*
3095	* item 0 key (13631488 EXTENT_ITEM 1048576) itemoff 3971 itemsize 24
3096	* refs 753 gen 6 flags DATA
3097	*
3098	* And that (13631488 EXTENT_DATA_REF <HASH>) gets removed.
3099	*/
3100	static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
3101	struct btrfs_delayed_ref_head *href,
3102	struct btrfs_delayed_ref_node *node, u64 parent,
3103	u64 root_objectid, u64 owner_objectid,
3104	u64 owner_offset,
3105	struct btrfs_delayed_extent_op *extent_op)
3106	{
3107	struct btrfs_fs_info *info = trans->fs_info;
3108	struct btrfs_key key;
3109	struct btrfs_path *path;
3110	struct btrfs_root *extent_root;
3111	struct extent_buffer *leaf;
3112	struct btrfs_extent_item *ei;
3113	struct btrfs_extent_inline_ref *iref;
3114	int ret;
3115	int is_data;
3116	int extent_slot = 0;
3117	int found_extent = 0;
3118	int num_to_del = 1;
3119	int refs_to_drop = node->ref_mod;
3120	u32 item_size;
3121	u64 refs;
3122	u64 bytenr = node->bytenr;
3123	u64 num_bytes = node->num_bytes;
3124	bool skinny_metadata = btrfs_fs_incompat(info, SKINNY_METADATA);
3125	u64 delayed_ref_root = href->owning_root;
3126
3127	extent_root = btrfs_extent_root(fs_info: info, bytenr);
3128	ASSERT(extent_root);
3129
3130	path = btrfs_alloc_path();
3131	if (!path)
3132	return -ENOMEM;
3133
3134	is_data = owner_objectid >= BTRFS_FIRST_FREE_OBJECTID;
3135
3136	if (!is_data && refs_to_drop != 1) {
3137	btrfs_crit(info,
3138	"invalid refs_to_drop, dropping more than 1 refs for tree block %llu refs_to_drop %u",
3139	node->bytenr, refs_to_drop);
3140	ret = -EINVAL;
3141	btrfs_abort_transaction(trans, ret);
3142	goto out;
3143	}
3144
3145	if (is_data)
3146	skinny_metadata = false;
3147
3148	ret = lookup_extent_backref(trans, path, ref_ret: &iref, bytenr, num_bytes,
3149	parent, root_objectid, owner: owner_objectid,
3150	offset: owner_offset);
3151	if (ret == 0) {
3152	/*
3153	* Either the inline backref or the SHARED_DATA_REF/
3154	* SHARED_BLOCK_REF is found
3155	*
3156	* Here is a quick path to locate EXTENT/METADATA_ITEM.
3157	* It's possible the EXTENT/METADATA_ITEM is near current slot.
3158	*/
3159	extent_slot = path->slots[0];
3160	while (extent_slot >= 0) {
3161	btrfs_item_key_to_cpu(eb: path->nodes[0], cpu_key: &key,
3162	nr: extent_slot);
3163	if (key.objectid != bytenr)
3164	break;
3165	if (key.type == BTRFS_EXTENT_ITEM_KEY &&
3166	key.offset == num_bytes) {
3167	found_extent = 1;
3168	break;
3169	}
3170	if (key.type == BTRFS_METADATA_ITEM_KEY &&
3171	key.offset == owner_objectid) {
3172	found_extent = 1;
3173	break;
3174	}
3175
3176	/* Quick path didn't find the EXTEMT/METADATA_ITEM */
3177	if (path->slots[0] - extent_slot > 5)
3178	break;
3179	extent_slot--;
3180	}
3181
3182	if (!found_extent) {
3183	if (iref) {
3184	abort_and_dump(trans, path,
3185	"invalid iref slot %u, no EXTENT/METADATA_ITEM found but has inline extent ref",
3186	path->slots[0]);
3187	ret = -EUCLEAN;
3188	goto out;
3189	}
3190	/* Must be SHARED_* item, remove the backref first */
3191	ret = remove_extent_backref(trans, root: extent_root, path,
3192	NULL, refs_to_drop, is_data);
3193	if (ret) {
3194	btrfs_abort_transaction(trans, ret);
3195	goto out;
3196	}
3197	btrfs_release_path(p: path);
3198
3199	/* Slow path to locate EXTENT/METADATA_ITEM */
3200	key.objectid = bytenr;
3201	key.type = BTRFS_EXTENT_ITEM_KEY;
3202	key.offset = num_bytes;
3203
3204	if (!is_data && skinny_metadata) {
3205	key.type = BTRFS_METADATA_ITEM_KEY;
3206	key.offset = owner_objectid;
3207	}
3208
3209	ret = btrfs_search_slot(trans, root: extent_root,
3210	key: &key, p: path, ins_len: -1, cow: 1);
3211	if (ret > 0 && skinny_metadata && path->slots[0]) {
3212	/*
3213	* Couldn't find our skinny metadata item,
3214	* see if we have ye olde extent item.
3215	*/
3216	path->slots[0]--;
3217	btrfs_item_key_to_cpu(eb: path->nodes[0], cpu_key: &key,
3218	nr: path->slots[0]);
3219	if (key.objectid == bytenr &&
3220	key.type == BTRFS_EXTENT_ITEM_KEY &&
3221	key.offset == num_bytes)
3222	ret = 0;
3223	}
3224
3225	if (ret > 0 && skinny_metadata) {
3226	skinny_metadata = false;
3227	key.objectid = bytenr;
3228	key.type = BTRFS_EXTENT_ITEM_KEY;
3229	key.offset = num_bytes;
3230	btrfs_release_path(p: path);
3231	ret = btrfs_search_slot(trans, root: extent_root,
3232	key: &key, p: path, ins_len: -1, cow: 1);
3233	}
3234
3235	if (ret) {
3236	if (ret > 0)
3237	btrfs_print_leaf(l: path->nodes[0]);
3238	btrfs_err(info,
3239	"umm, got %d back from search, was looking for %llu, slot %d",
3240	ret, bytenr, path->slots[0]);
3241	}
3242	if (ret < 0) {
3243	btrfs_abort_transaction(trans, ret);
3244	goto out;
3245	}
3246	extent_slot = path->slots[0];
3247	}
3248	} else if (WARN_ON(ret == -ENOENT)) {
3249	abort_and_dump(trans, path,
3250	"unable to find ref byte nr %llu parent %llu root %llu owner %llu offset %llu slot %d",
3251	bytenr, parent, root_objectid, owner_objectid,
3252	owner_offset, path->slots[0]);
3253	goto out;
3254	} else {
3255	btrfs_abort_transaction(trans, ret);
3256	goto out;
3257	}
3258
3259	leaf = path->nodes[0];
3260	item_size = btrfs_item_size(eb: leaf, slot: extent_slot);
3261	if (unlikely(item_size < sizeof(*ei))) {
3262	ret = -EUCLEAN;
3263	btrfs_err(trans->fs_info,
3264	"unexpected extent item size, has %u expect >= %zu",
3265	item_size, sizeof(*ei));
3266	btrfs_abort_transaction(trans, ret);
3267	goto out;
3268	}
3269	ei = btrfs_item_ptr(leaf, extent_slot,
3270	struct btrfs_extent_item);
3271	if (owner_objectid < BTRFS_FIRST_FREE_OBJECTID &&
3272	key.type == BTRFS_EXTENT_ITEM_KEY) {
3273	struct btrfs_tree_block_info *bi;
3274
3275	if (item_size < sizeof(*ei) + sizeof(*bi)) {
3276	abort_and_dump(trans, path,
3277	"invalid extent item size for key (%llu, %u, %llu) slot %u owner %llu, has %u expect >= %zu",
3278	key.objectid, key.type, key.offset,
3279	path->slots[0], owner_objectid, item_size,
3280	sizeof(*ei) + sizeof(*bi));
3281	ret = -EUCLEAN;
3282	goto out;
3283	}
3284	bi = (struct btrfs_tree_block_info *)(ei + 1);
3285	WARN_ON(owner_objectid != btrfs_tree_block_level(leaf, bi));
3286	}
3287
3288	refs = btrfs_extent_refs(eb: leaf, s: ei);
3289	if (refs < refs_to_drop) {
3290	abort_and_dump(trans, path,
3291	"trying to drop %d refs but we only have %llu for bytenr %llu slot %u",
3292	refs_to_drop, refs, bytenr, path->slots[0]);
3293	ret = -EUCLEAN;
3294	goto out;
3295	}
3296	refs -= refs_to_drop;
3297
3298	if (refs > 0) {
3299	if (extent_op)
3300	__run_delayed_extent_op(extent_op, leaf, ei);
3301	/*
3302	* In the case of inline back ref, reference count will
3303	* be updated by remove_extent_backref
3304	*/
3305	if (iref) {
3306	if (!found_extent) {
3307	abort_and_dump(trans, path,
3308	"invalid iref, got inlined extent ref but no EXTENT/METADATA_ITEM found, slot %u",
3309	path->slots[0]);
3310	ret = -EUCLEAN;
3311	goto out;
3312	}
3313	} else {
3314	btrfs_set_extent_refs(eb: leaf, s: ei, val: refs);
3315	btrfs_mark_buffer_dirty(trans, buf: leaf);
3316	}
3317	if (found_extent) {
3318	ret = remove_extent_backref(trans, root: extent_root, path,
3319	iref, refs_to_drop, is_data);
3320	if (ret) {
3321	btrfs_abort_transaction(trans, ret);
3322	goto out;
3323	}
3324	}
3325	} else {
3326	struct btrfs_squota_delta delta = {
3327	.root = delayed_ref_root,
3328	.num_bytes = num_bytes,
3329	.is_data = is_data,
3330	.is_inc = false,
3331	.generation = btrfs_extent_generation(eb: leaf, s: ei),
3332	};
3333
3334	/* In this branch refs == 1 */
3335	if (found_extent) {
3336	if (is_data && refs_to_drop !=
3337	extent_data_ref_count(path, iref)) {
3338	abort_and_dump(trans, path,
3339	"invalid refs_to_drop, current refs %u refs_to_drop %u slot %u",
3340	extent_data_ref_count(path, iref),
3341	refs_to_drop, path->slots[0]);
3342	ret = -EUCLEAN;
3343	goto out;
3344	}
3345	if (iref) {
3346	if (path->slots[0] != extent_slot) {
3347	abort_and_dump(trans, path,
3348	"invalid iref, extent item key (%llu %u %llu) slot %u doesn't have wanted iref",
3349	key.objectid, key.type,
3350	key.offset, path->slots[0]);
3351	ret = -EUCLEAN;
3352	goto out;
3353	}
3354	} else {
3355	/*
3356	* No inline ref, we must be at SHARED_* item,
3357	* And it's single ref, it must be:
3358	* | extent_slot ||extent_slot + 1|
3359	* [ EXTENT/METADATA_ITEM ][ SHARED_* ITEM ]
3360	*/
3361	if (path->slots[0] != extent_slot + 1) {
3362	abort_and_dump(trans, path,
3363	"invalid SHARED_* item slot %u, previous item is not EXTENT/METADATA_ITEM",
3364	path->slots[0]);
3365	ret = -EUCLEAN;
3366	goto out;
3367	}
3368	path->slots[0] = extent_slot;
3369	num_to_del = 2;
3370	}
3371	}
3372	/*
3373	* We can't infer the data owner from the delayed ref, so we need
3374	* to try to get it from the owning ref item.
3375	*
3376	* If it is not present, then that extent was not written under
3377	* simple quotas mode, so we don't need to account for its deletion.
3378	*/
3379	if (is_data)
3380	delta.root = btrfs_get_extent_owner_root(fs_info: trans->fs_info,
3381	leaf, slot: extent_slot);
3382
3383	ret = btrfs_del_items(trans, root: extent_root, path, slot: path->slots[0],
3384	nr: num_to_del);
3385	if (ret) {
3386	btrfs_abort_transaction(trans, ret);
3387	goto out;
3388	}
3389	btrfs_release_path(p: path);
3390
3391	ret = do_free_extent_accounting(trans, bytenr, delta: &delta);
3392	}
3393	btrfs_release_path(p: path);
3394
3395	out:
3396	btrfs_free_path(p: path);
3397	return ret;
3398	}
3399
3400	/*
3401	* when we free an block, it is possible (and likely) that we free the last
3402	* delayed ref for that extent as well. This searches the delayed ref tree for
3403	* a given extent, and if there are no other delayed refs to be processed, it
3404	* removes it from the tree.
3405	*/
3406	static noinline int check_ref_cleanup(struct btrfs_trans_handle *trans,
3407	u64 bytenr)
3408	{
3409	struct btrfs_delayed_ref_head *head;
3410	struct btrfs_delayed_ref_root *delayed_refs;
3411	int ret = 0;
3412
3413	delayed_refs = &trans->transaction->delayed_refs;
3414	spin_lock(lock: &delayed_refs->lock);
3415	head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
3416	if (!head)
3417	goto out_delayed_unlock;
3418
3419	spin_lock(lock: &head->lock);
3420	if (!RB_EMPTY_ROOT(&head->ref_tree.rb_root))
3421	goto out;
3422
3423	if (cleanup_extent_op(head) != NULL)
3424	goto out;
3425
3426	/*
3427	* waiting for the lock here would deadlock. If someone else has it
3428	* locked they are already in the process of dropping it anyway
3429	*/
3430	if (!mutex_trylock(lock: &head->mutex))
3431	goto out;
3432
3433	btrfs_delete_ref_head(delayed_refs, head);
3434	head->processing = false;
3435
3436	spin_unlock(lock: &head->lock);
3437	spin_unlock(lock: &delayed_refs->lock);
3438
3439	BUG_ON(head->extent_op);
3440	if (head->must_insert_reserved)
3441	ret = 1;
3442
3443	btrfs_cleanup_ref_head_accounting(fs_info: trans->fs_info, delayed_refs, head);
3444	mutex_unlock(lock: &head->mutex);
3445	btrfs_put_delayed_ref_head(head);
3446	return ret;
3447	out:
3448	spin_unlock(lock: &head->lock);
3449
3450	out_delayed_unlock:
3451	spin_unlock(lock: &delayed_refs->lock);
3452	return 0;
3453	}
3454
3455	void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
3456	u64 root_id,
3457	struct extent_buffer *buf,
3458	u64 parent, int last_ref)
3459	{
3460	struct btrfs_fs_info *fs_info = trans->fs_info;
3461	struct btrfs_block_group *bg;
3462	int ret;
3463
3464	if (root_id != BTRFS_TREE_LOG_OBJECTID) {
3465	struct btrfs_ref generic_ref = { 0 };
3466
3467	/*
3468	* Assert that the extent buffer is not cleared due to
3469	* EXTENT_BUFFER_ZONED_ZEROOUT. Please refer
3470	* btrfs_clear_buffer_dirty() and btree_csum_one_bio() for
3471	* detail.
3472	*/
3473	ASSERT(btrfs_header_bytenr(buf) != 0);
3474
3475	btrfs_init_generic_ref(generic_ref: &generic_ref, action: BTRFS_DROP_DELAYED_REF,
3476	bytenr: buf->start, len: buf->len, parent,
3477	owning_root: btrfs_header_owner(eb: buf));
3478	btrfs_init_tree_ref(generic_ref: &generic_ref, level: btrfs_header_level(eb: buf),
3479	root: root_id, mod_root: 0, skip_qgroup: false);
3480	btrfs_ref_tree_mod(fs_info, generic_ref: &generic_ref);
3481	ret = btrfs_add_delayed_tree_ref(trans, generic_ref: &generic_ref, NULL);
3482	BUG_ON(ret); /* -ENOMEM */
3483	}
3484
3485	if (!last_ref)
3486	return;
3487
3488	if (btrfs_header_generation(eb: buf) != trans->transid)
3489	goto out;
3490
3491	if (root_id != BTRFS_TREE_LOG_OBJECTID) {
3492	ret = check_ref_cleanup(trans, bytenr: buf->start);
3493	if (!ret)
3494	goto out;
3495	}
3496
3497	bg = btrfs_lookup_block_group(info: fs_info, bytenr: buf->start);
3498
3499	if (btrfs_header_flag(eb: buf, BTRFS_HEADER_FLAG_WRITTEN)) {
3500	pin_down_extent(trans, cache: bg, bytenr: buf->start, num_bytes: buf->len, reserved: 1);
3501	btrfs_put_block_group(cache: bg);
3502	goto out;
3503	}
3504
3505	/*
3506	* If there are tree mod log users we may have recorded mod log
3507	* operations for this node. If we re-allocate this node we
3508	* could replay operations on this node that happened when it
3509	* existed in a completely different root. For example if it
3510	* was part of root A, then was reallocated to root B, and we
3511	* are doing a btrfs_old_search_slot(root b), we could replay
3512	* operations that happened when the block was part of root A,
3513	* giving us an inconsistent view of the btree.
3514	*
3515	* We are safe from races here because at this point no other
3516	* node or root points to this extent buffer, so if after this
3517	* check a new tree mod log user joins we will not have an
3518	* existing log of operations on this node that we have to
3519	* contend with.
3520	*/
3521
3522	if (test_bit(BTRFS_FS_TREE_MOD_LOG_USERS, &fs_info->flags)
3523	|| btrfs_is_zoned(fs_info)) {
3524	pin_down_extent(trans, cache: bg, bytenr: buf->start, num_bytes: buf->len, reserved: 1);
3525	btrfs_put_block_group(cache: bg);
3526	goto out;
3527	}
3528
3529	WARN_ON(test_bit(EXTENT_BUFFER_DIRTY, &buf->bflags));
3530
3531	btrfs_add_free_space(block_group: bg, bytenr: buf->start, size: buf->len);
3532	btrfs_free_reserved_bytes(cache: bg, num_bytes: buf->len, delalloc: 0);
3533	btrfs_put_block_group(cache: bg);
3534	trace_btrfs_reserved_extent_free(fs_info, start: buf->start, len: buf->len);
3535
3536	out:
3537
3538	/*
3539	* Deleting the buffer, clear the corrupt flag since it doesn't
3540	* matter anymore.
3541	*/
3542	clear_bit(nr: EXTENT_BUFFER_CORRUPT, addr: &buf->bflags);
3543	}
3544
3545	/* Can return -ENOMEM */
3546	int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_ref *ref)
3547	{
3548	struct btrfs_fs_info *fs_info = trans->fs_info;
3549	int ret;
3550
3551	if (btrfs_is_testing(fs_info))
3552	return 0;
3553
3554	/*
3555	* tree log blocks never actually go into the extent allocation
3556	* tree, just update pinning info and exit early.
3557	*/
3558	if ((ref->type == BTRFS_REF_METADATA &&
3559	ref->tree_ref.ref_root == BTRFS_TREE_LOG_OBJECTID) ||
3560	(ref->type == BTRFS_REF_DATA &&
3561	ref->data_ref.ref_root == BTRFS_TREE_LOG_OBJECTID)) {
3562	btrfs_pin_extent(trans, bytenr: ref->bytenr, num_bytes: ref->len, reserved: 1);
3563	ret = 0;
3564	} else if (ref->type == BTRFS_REF_METADATA) {
3565	ret = btrfs_add_delayed_tree_ref(trans, generic_ref: ref, NULL);
3566	} else {
3567	ret = btrfs_add_delayed_data_ref(trans, generic_ref: ref, reserved: 0);
3568	}
3569
3570	if (!((ref->type == BTRFS_REF_METADATA &&
3571	ref->tree_ref.ref_root == BTRFS_TREE_LOG_OBJECTID) ||
3572	(ref->type == BTRFS_REF_DATA &&
3573	ref->data_ref.ref_root == BTRFS_TREE_LOG_OBJECTID)))
3574	btrfs_ref_tree_mod(fs_info, generic_ref: ref);
3575
3576	return ret;
3577	}
3578
3579	enum btrfs_loop_type {
3580	/*
3581	* Start caching block groups but do not wait for progress or for them
3582	* to be done.
3583	*/
3584	LOOP_CACHING_NOWAIT,
3585
3586	/*
3587	* Wait for the block group free_space >= the space we're waiting for if
3588	* the block group isn't cached.
3589	*/
3590	LOOP_CACHING_WAIT,
3591
3592	/*
3593	* Allow allocations to happen from block groups that do not yet have a
3594	* size classification.
3595	*/
3596	LOOP_UNSET_SIZE_CLASS,
3597
3598	/*
3599	* Allocate a chunk and then retry the allocation.
3600	*/
3601	LOOP_ALLOC_CHUNK,
3602
3603	/*
3604	* Ignore the size class restrictions for this allocation.
3605	*/
3606	LOOP_WRONG_SIZE_CLASS,
3607
3608	/*
3609	* Ignore the empty size, only try to allocate the number of bytes
3610	* needed for this allocation.
3611	*/
3612	LOOP_NO_EMPTY_SIZE,
3613	};
3614
3615	static inline void
3616	btrfs_lock_block_group(struct btrfs_block_group *cache,
3617	int delalloc)
3618	{
3619	if (delalloc)
3620	down_read(sem: &cache->data_rwsem);
3621	}
3622
3623	static inline void btrfs_grab_block_group(struct btrfs_block_group *cache,
3624	int delalloc)
3625	{
3626	btrfs_get_block_group(cache);
3627	if (delalloc)
3628	down_read(sem: &cache->data_rwsem);
3629	}
3630
3631	static struct btrfs_block_group *btrfs_lock_cluster(
3632	struct btrfs_block_group *block_group,
3633	struct btrfs_free_cluster *cluster,
3634	int delalloc)
3635	__acquires(&cluster->refill_lock)
3636	{
3637	struct btrfs_block_group *used_bg = NULL;
3638
3639	spin_lock(lock: &cluster->refill_lock);
3640	while (1) {
3641	used_bg = cluster->block_group;
3642	if (!used_bg)
3643	return NULL;
3644
3645	if (used_bg == block_group)
3646	return used_bg;
3647
3648	btrfs_get_block_group(cache: used_bg);
3649
3650	if (!delalloc)
3651	return used_bg;
3652
3653	if (down_read_trylock(sem: &used_bg->data_rwsem))
3654	return used_bg;
3655
3656	spin_unlock(lock: &cluster->refill_lock);
3657
3658	/* We should only have one-level nested. */
3659	down_read_nested(sem: &used_bg->data_rwsem, SINGLE_DEPTH_NESTING);
3660
3661	spin_lock(lock: &cluster->refill_lock);
3662	if (used_bg == cluster->block_group)
3663	return used_bg;
3664
3665	up_read(sem: &used_bg->data_rwsem);
3666	btrfs_put_block_group(cache: used_bg);
3667	}
3668	}
3669
3670	static inline void
3671	btrfs_release_block_group(struct btrfs_block_group *cache,
3672	int delalloc)
3673	{
3674	if (delalloc)
3675	up_read(sem: &cache->data_rwsem);
3676	btrfs_put_block_group(cache);
3677	}
3678
3679	/*
3680	* Helper function for find_free_extent().
3681	*
3682	* Return -ENOENT to inform caller that we need fallback to unclustered mode.
3683	* Return >0 to inform caller that we find nothing
3684	* Return 0 means we have found a location and set ffe_ctl->found_offset.
3685	*/
3686	static int find_free_extent_clustered(struct btrfs_block_group *bg,
3687	struct find_free_extent_ctl *ffe_ctl,
3688	struct btrfs_block_group **cluster_bg_ret)
3689	{
3690	struct btrfs_block_group *cluster_bg;
3691	struct btrfs_free_cluster *last_ptr = ffe_ctl->last_ptr;
3692	u64 aligned_cluster;
3693	u64 offset;
3694	int ret;
3695
3696	cluster_bg = btrfs_lock_cluster(block_group: bg, cluster: last_ptr, delalloc: ffe_ctl->delalloc);
3697	if (!cluster_bg)
3698	goto refill_cluster;
3699	if (cluster_bg != bg && (cluster_bg->ro ||
3700	!block_group_bits(cache: cluster_bg, bits: ffe_ctl->flags)))
3701	goto release_cluster;
3702
3703	offset = btrfs_alloc_from_cluster(block_group: cluster_bg, cluster: last_ptr,
3704	bytes: ffe_ctl->num_bytes, min_start: cluster_bg->start,
3705	max_extent_size: &ffe_ctl->max_extent_size);
3706	if (offset) {
3707	/* We have a block, we're done */
3708	spin_unlock(lock: &last_ptr->refill_lock);
3709	trace_btrfs_reserve_extent_cluster(block_group: cluster_bg, ffe_ctl);
3710	*cluster_bg_ret = cluster_bg;
3711	ffe_ctl->found_offset = offset;
3712	return 0;
3713	}
3714	WARN_ON(last_ptr->block_group != cluster_bg);
3715
3716	release_cluster:
3717	/*
3718	* If we are on LOOP_NO_EMPTY_SIZE, we can't set up a new clusters, so
3719	* lets just skip it and let the allocator find whatever block it can
3720	* find. If we reach this point, we will have tried the cluster
3721	* allocator plenty of times and not have found anything, so we are
3722	* likely way too fragmented for the clustering stuff to find anything.
3723	*
3724	* However, if the cluster is taken from the current block group,
3725	* release the cluster first, so that we stand a better chance of
3726	* succeeding in the unclustered allocation.
3727	*/
3728	if (ffe_ctl->loop >= LOOP_NO_EMPTY_SIZE && cluster_bg != bg) {
3729	spin_unlock(lock: &last_ptr->refill_lock);
3730	btrfs_release_block_group(cache: cluster_bg, delalloc: ffe_ctl->delalloc);
3731	return -ENOENT;
3732	}
3733
3734	/* This cluster didn't work out, free it and start over */
3735	btrfs_return_cluster_to_free_space(NULL, cluster: last_ptr);
3736
3737	if (cluster_bg != bg)
3738	btrfs_release_block_group(cache: cluster_bg, delalloc: ffe_ctl->delalloc);
3739
3740	refill_cluster:
3741	if (ffe_ctl->loop >= LOOP_NO_EMPTY_SIZE) {
3742	spin_unlock(lock: &last_ptr->refill_lock);
3743	return -ENOENT;
3744	}
3745
3746	aligned_cluster = max_t(u64,
3747	ffe_ctl->empty_cluster + ffe_ctl->empty_size,
3748	bg->full_stripe_len);
3749	ret = btrfs_find_space_cluster(block_group: bg, cluster: last_ptr, offset: ffe_ctl->search_start,
3750	bytes: ffe_ctl->num_bytes, empty_size: aligned_cluster);
3751	if (ret == 0) {
3752	/* Now pull our allocation out of this cluster */
3753	offset = btrfs_alloc_from_cluster(block_group: bg, cluster: last_ptr,
3754	bytes: ffe_ctl->num_bytes, min_start: ffe_ctl->search_start,
3755	max_extent_size: &ffe_ctl->max_extent_size);
3756	if (offset) {
3757	/* We found one, proceed */
3758	spin_unlock(lock: &last_ptr->refill_lock);
3759	ffe_ctl->found_offset = offset;
3760	trace_btrfs_reserve_extent_cluster(block_group: bg, ffe_ctl);
3761	return 0;
3762	}
3763	}
3764	/*
3765	* At this point we either didn't find a cluster or we weren't able to
3766	* allocate a block from our cluster. Free the cluster we've been
3767	* trying to use, and go to the next block group.
3768	*/
3769	btrfs_return_cluster_to_free_space(NULL, cluster: last_ptr);
3770	spin_unlock(lock: &last_ptr->refill_lock);
3771	return 1;
3772	}
3773
3774	/*
3775	* Return >0 to inform caller that we find nothing
3776	* Return 0 when we found an free extent and set ffe_ctrl->found_offset
3777	*/
3778	static int find_free_extent_unclustered(struct btrfs_block_group *bg,
3779	struct find_free_extent_ctl *ffe_ctl)
3780	{
3781	struct btrfs_free_cluster *last_ptr = ffe_ctl->last_ptr;
3782	u64 offset;
3783
3784	/*
3785	* We are doing an unclustered allocation, set the fragmented flag so
3786	* we don't bother trying to setup a cluster again until we get more
3787	* space.
3788	*/
3789	if (unlikely(last_ptr)) {
3790	spin_lock(lock: &last_ptr->lock);
3791	last_ptr->fragmented = 1;
3792	spin_unlock(lock: &last_ptr->lock);
3793	}
3794	if (ffe_ctl->cached) {
3795	struct btrfs_free_space_ctl *free_space_ctl;
3796
3797	free_space_ctl = bg->free_space_ctl;
3798	spin_lock(lock: &free_space_ctl->tree_lock);
3799	if (free_space_ctl->free_space <
3800	ffe_ctl->num_bytes + ffe_ctl->empty_cluster +
3801	ffe_ctl->empty_size) {
3802	ffe_ctl->total_free_space = max_t(u64,
3803	ffe_ctl->total_free_space,
3804	free_space_ctl->free_space);
3805	spin_unlock(lock: &free_space_ctl->tree_lock);
3806	return 1;
3807	}
3808	spin_unlock(lock: &free_space_ctl->tree_lock);
3809	}
3810
3811	offset = btrfs_find_space_for_alloc(block_group: bg, offset: ffe_ctl->search_start,
3812	bytes: ffe_ctl->num_bytes, empty_size: ffe_ctl->empty_size,
3813	max_extent_size: &ffe_ctl->max_extent_size);
3814	if (!offset)
3815	return 1;
3816	ffe_ctl->found_offset = offset;
3817	return 0;
3818	}
3819
3820	static int do_allocation_clustered(struct btrfs_block_group *block_group,
3821	struct find_free_extent_ctl *ffe_ctl,
3822	struct btrfs_block_group **bg_ret)
3823	{
3824	int ret;
3825
3826	/* We want to try and use the cluster allocator, so lets look there */
3827	if (ffe_ctl->last_ptr && ffe_ctl->use_cluster) {
3828	ret = find_free_extent_clustered(bg: block_group, ffe_ctl, cluster_bg_ret: bg_ret);
3829	if (ret >= 0)
3830	return ret;
3831	/* ret == -ENOENT case falls through */
3832	}
3833
3834	return find_free_extent_unclustered(bg: block_group, ffe_ctl);
3835	}
3836
3837	/*
3838	* Tree-log block group locking
3839	* ============================
3840	*
3841	* fs_info::treelog_bg_lock protects the fs_info::treelog_bg which
3842	* indicates the starting address of a block group, which is reserved only
3843	* for tree-log metadata.
3844	*
3845	* Lock nesting
3846	* ============
3847	*
3848	* space_info::lock
3849	* block_group::lock
3850	* fs_info::treelog_bg_lock
3851	*/
3852
3853	/*
3854	* Simple allocator for sequential-only block group. It only allows sequential
3855	* allocation. No need to play with trees. This function also reserves the
3856	* bytes as in btrfs_add_reserved_bytes.
3857	*/
3858	static int do_allocation_zoned(struct btrfs_block_group *block_group,
3859	struct find_free_extent_ctl *ffe_ctl,
3860	struct btrfs_block_group **bg_ret)
3861	{
3862	struct btrfs_fs_info *fs_info = block_group->fs_info;
3863	struct btrfs_space_info *space_info = block_group->space_info;
3864	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
3865	u64 start = block_group->start;
3866	u64 num_bytes = ffe_ctl->num_bytes;
3867	u64 avail;
3868	u64 bytenr = block_group->start;
3869	u64 log_bytenr;
3870	u64 data_reloc_bytenr;
3871	int ret = 0;
3872	bool skip = false;
3873
3874	ASSERT(btrfs_is_zoned(block_group->fs_info));
3875
3876	/*
3877	* Do not allow non-tree-log blocks in the dedicated tree-log block
3878	* group, and vice versa.
3879	*/
3880	spin_lock(lock: &fs_info->treelog_bg_lock);
3881	log_bytenr = fs_info->treelog_bg;
3882	if (log_bytenr && ((ffe_ctl->for_treelog && bytenr != log_bytenr) ||
3883	(!ffe_ctl->for_treelog && bytenr == log_bytenr)))
3884	skip = true;
3885	spin_unlock(lock: &fs_info->treelog_bg_lock);
3886	if (skip)
3887	return 1;
3888
3889	/*
3890	* Do not allow non-relocation blocks in the dedicated relocation block
3891	* group, and vice versa.
3892	*/
3893	spin_lock(lock: &fs_info->relocation_bg_lock);
3894	data_reloc_bytenr = fs_info->data_reloc_bg;
3895	if (data_reloc_bytenr &&
3896	((ffe_ctl->for_data_reloc && bytenr != data_reloc_bytenr) ||
3897	(!ffe_ctl->for_data_reloc && bytenr == data_reloc_bytenr)))
3898	skip = true;
3899	spin_unlock(lock: &fs_info->relocation_bg_lock);
3900	if (skip)
3901	return 1;
3902
3903	/* Check RO and no space case before trying to activate it */
3904	spin_lock(lock: &block_group->lock);
3905	if (block_group->ro || btrfs_zoned_bg_is_full(bg: block_group)) {
3906	ret = 1;
3907	/*
3908	* May need to clear fs_info->{treelog,data_reloc}_bg.
3909	* Return the error after taking the locks.
3910	*/
3911	}
3912	spin_unlock(lock: &block_group->lock);
3913
3914	/* Metadata block group is activated at write time. */
3915	if (!ret && (block_group->flags & BTRFS_BLOCK_GROUP_DATA) &&
3916	!btrfs_zone_activate(block_group)) {
3917	ret = 1;
3918	/*
3919	* May need to clear fs_info->{treelog,data_reloc}_bg.
3920	* Return the error after taking the locks.
3921	*/
3922	}
3923
3924	spin_lock(lock: &space_info->lock);
3925	spin_lock(lock: &block_group->lock);
3926	spin_lock(lock: &fs_info->treelog_bg_lock);
3927	spin_lock(lock: &fs_info->relocation_bg_lock);
3928
3929	if (ret)
3930	goto out;
3931
3932	ASSERT(!ffe_ctl->for_treelog ||
3933	block_group->start == fs_info->treelog_bg ||
3934	fs_info->treelog_bg == 0);
3935	ASSERT(!ffe_ctl->for_data_reloc ||
3936	block_group->start == fs_info->data_reloc_bg ||
3937	fs_info->data_reloc_bg == 0);
3938
3939	if (block_group->ro ||
3940	(!ffe_ctl->for_data_reloc &&
3941	test_bit(BLOCK_GROUP_FLAG_ZONED_DATA_RELOC, &block_group->runtime_flags))) {
3942	ret = 1;
3943	goto out;
3944	}
3945
3946	/*
3947	* Do not allow currently using block group to be tree-log dedicated
3948	* block group.
3949	*/
3950	if (ffe_ctl->for_treelog && !fs_info->treelog_bg &&
3951	(block_group->used || block_group->reserved)) {
3952	ret = 1;
3953	goto out;
3954	}
3955
3956	/*
3957	* Do not allow currently used block group to be the data relocation
3958	* dedicated block group.
3959	*/
3960	if (ffe_ctl->for_data_reloc && !fs_info->data_reloc_bg &&
3961	(block_group->used || block_group->reserved)) {
3962	ret = 1;
3963	goto out;
3964	}
3965
3966	WARN_ON_ONCE(block_group->alloc_offset > block_group->zone_capacity);
3967	avail = block_group->zone_capacity - block_group->alloc_offset;
3968	if (avail < num_bytes) {
3969	if (ffe_ctl->max_extent_size < avail) {
3970	/*
3971	* With sequential allocator, free space is always
3972	* contiguous
3973	*/
3974	ffe_ctl->max_extent_size = avail;
3975	ffe_ctl->total_free_space = avail;
3976	}
3977	ret = 1;
3978	goto out;
3979	}
3980
3981	if (ffe_ctl->for_treelog && !fs_info->treelog_bg)
3982	fs_info->treelog_bg = block_group->start;
3983
3984	if (ffe_ctl->for_data_reloc) {
3985	if (!fs_info->data_reloc_bg)
3986	fs_info->data_reloc_bg = block_group->start;
3987	/*
3988	* Do not allow allocations from this block group, unless it is
3989	* for data relocation. Compared to increasing the ->ro, setting
3990	* the ->zoned_data_reloc_ongoing flag still allows nocow
3991	* writers to come in. See btrfs_inc_nocow_writers().
3992	*
3993	* We need to disable an allocation to avoid an allocation of
3994	* regular (non-relocation data) extent. With mix of relocation
3995	* extents and regular extents, we can dispatch WRITE commands
3996	* (for relocation extents) and ZONE APPEND commands (for
3997	* regular extents) at the same time to the same zone, which
3998	* easily break the write pointer.
3999	*
4000	* Also, this flag avoids this block group to be zone finished.
4001	*/
4002	set_bit(nr: BLOCK_GROUP_FLAG_ZONED_DATA_RELOC, addr: &block_group->runtime_flags);
4003	}
4004
4005	ffe_ctl->found_offset = start + block_group->alloc_offset;
4006	block_group->alloc_offset += num_bytes;
4007	spin_lock(lock: &ctl->tree_lock);
4008	ctl->free_space -= num_bytes;
4009	spin_unlock(lock: &ctl->tree_lock);
4010
4011	/*
4012	* We do not check if found_offset is aligned to stripesize. The
4013	* address is anyway rewritten when using zone append writing.
4014	*/
4015
4016	ffe_ctl->search_start = ffe_ctl->found_offset;
4017
4018	out:
4019	if (ret && ffe_ctl->for_treelog)
4020	fs_info->treelog_bg = 0;
4021	if (ret && ffe_ctl->for_data_reloc)
4022	fs_info->data_reloc_bg = 0;
4023	spin_unlock(lock: &fs_info->relocation_bg_lock);
4024	spin_unlock(lock: &fs_info->treelog_bg_lock);
4025	spin_unlock(lock: &block_group->lock);
4026	spin_unlock(lock: &space_info->lock);
4027	return ret;
4028	}
4029
4030	static int do_allocation(struct btrfs_block_group *block_group,
4031	struct find_free_extent_ctl *ffe_ctl,
4032	struct btrfs_block_group **bg_ret)
4033	{
4034	switch (ffe_ctl->policy) {
4035	case BTRFS_EXTENT_ALLOC_CLUSTERED:
4036	return do_allocation_clustered(block_group, ffe_ctl, bg_ret);
4037	case BTRFS_EXTENT_ALLOC_ZONED:
4038	return do_allocation_zoned(block_group, ffe_ctl, bg_ret);
4039	default:
4040	BUG();
4041	}
4042	}
4043
4044	static void release_block_group(struct btrfs_block_group *block_group,
4045	struct find_free_extent_ctl *ffe_ctl,
4046	int delalloc)
4047	{
4048	switch (ffe_ctl->policy) {
4049	case BTRFS_EXTENT_ALLOC_CLUSTERED:
4050	ffe_ctl->retry_uncached = false;
4051	break;
4052	case BTRFS_EXTENT_ALLOC_ZONED:
4053	/* Nothing to do */
4054	break;
4055	default:
4056	BUG();
4057	}
4058
4059	BUG_ON(btrfs_bg_flags_to_raid_index(block_group->flags) !=
4060	ffe_ctl->index);
4061	btrfs_release_block_group(cache: block_group, delalloc);
4062	}
4063
4064	static void found_extent_clustered(struct find_free_extent_ctl *ffe_ctl,
4065	struct btrfs_key *ins)
4066	{
4067	struct btrfs_free_cluster *last_ptr = ffe_ctl->last_ptr;
4068
4069	if (!ffe_ctl->use_cluster && last_ptr) {
4070	spin_lock(lock: &last_ptr->lock);
4071	last_ptr->window_start = ins->objectid;
4072	spin_unlock(lock: &last_ptr->lock);
4073	}
4074	}
4075
4076	static void found_extent(struct find_free_extent_ctl *ffe_ctl,
4077	struct btrfs_key *ins)
4078	{
4079	switch (ffe_ctl->policy) {
4080	case BTRFS_EXTENT_ALLOC_CLUSTERED:
4081	found_extent_clustered(ffe_ctl, ins);
4082	break;
4083	case BTRFS_EXTENT_ALLOC_ZONED:
4084	/* Nothing to do */
4085	break;
4086	default:
4087	BUG();
4088	}
4089	}
4090
4091	static int can_allocate_chunk_zoned(struct btrfs_fs_info *fs_info,
4092	struct find_free_extent_ctl *ffe_ctl)
4093	{
4094	/* Block group's activeness is not a requirement for METADATA block groups. */
4095	if (!(ffe_ctl->flags & BTRFS_BLOCK_GROUP_DATA))
4096	return 0;
4097
4098	/* If we can activate new zone, just allocate a chunk and use it */
4099	if (btrfs_can_activate_zone(fs_devices: fs_info->fs_devices, flags: ffe_ctl->flags))
4100	return 0;
4101
4102	/*
4103	* We already reached the max active zones. Try to finish one block
4104	* group to make a room for a new block group. This is only possible
4105	* for a data block group because btrfs_zone_finish() may need to wait
4106	* for a running transaction which can cause a deadlock for metadata
4107	* allocation.
4108	*/
4109	if (ffe_ctl->flags & BTRFS_BLOCK_GROUP_DATA) {
4110	int ret = btrfs_zone_finish_one_bg(fs_info);
4111
4112	if (ret == 1)
4113	return 0;
4114	else if (ret < 0)
4115	return ret;
4116	}
4117
4118	/*
4119	* If we have enough free space left in an already active block group
4120	* and we can't activate any other zone now, do not allow allocating a
4121	* new chunk and let find_free_extent() retry with a smaller size.
4122	*/
4123	if (ffe_ctl->max_extent_size >= ffe_ctl->min_alloc_size)
4124	return -ENOSPC;
4125
4126	/*
4127	* Even min_alloc_size is not left in any block groups. Since we cannot
4128	* activate a new block group, allocating it may not help. Let's tell a
4129	* caller to try again and hope it progress something by writing some
4130	* parts of the region. That is only possible for data block groups,
4131	* where a part of the region can be written.
4132	*/
4133	if (ffe_ctl->flags & BTRFS_BLOCK_GROUP_DATA)
4134	return -EAGAIN;
4135
4136	/*
4137	* We cannot activate a new block group and no enough space left in any
4138	* block groups. So, allocating a new block group may not help. But,
4139	* there is nothing to do anyway, so let's go with it.
4140	*/
4141	return 0;
4142	}
4143
4144	static int can_allocate_chunk(struct btrfs_fs_info *fs_info,
4145	struct find_free_extent_ctl *ffe_ctl)
4146	{
4147	switch (ffe_ctl->policy) {
4148	case BTRFS_EXTENT_ALLOC_CLUSTERED:
4149	return 0;
4150	case BTRFS_EXTENT_ALLOC_ZONED:
4151	return can_allocate_chunk_zoned(fs_info, ffe_ctl);
4152	default:
4153	BUG();
4154	}
4155	}
4156
4157	/*
4158	* Return >0 means caller needs to re-search for free extent
4159	* Return 0 means we have the needed free extent.
4160	* Return <0 means we failed to locate any free extent.
4161	*/
4162	static int find_free_extent_update_loop(struct btrfs_fs_info *fs_info,
4163	struct btrfs_key *ins,
4164	struct find_free_extent_ctl *ffe_ctl,
4165	bool full_search)
4166	{
4167	struct btrfs_root *root = fs_info->chunk_root;
4168	int ret;
4169
4170	if ((ffe_ctl->loop == LOOP_CACHING_NOWAIT) &&
4171	ffe_ctl->have_caching_bg && !ffe_ctl->orig_have_caching_bg)
4172	ffe_ctl->orig_have_caching_bg = true;
4173
4174	if (ins->objectid) {
4175	found_extent(ffe_ctl, ins);
4176	return 0;
4177	}
4178
4179	if (ffe_ctl->loop >= LOOP_CACHING_WAIT && ffe_ctl->have_caching_bg)
4180	return 1;
4181
4182	ffe_ctl->index++;
4183	if (ffe_ctl->index < BTRFS_NR_RAID_TYPES)
4184	return 1;
4185
4186	/* See the comments for btrfs_loop_type for an explanation of the phases. */
4187	if (ffe_ctl->loop < LOOP_NO_EMPTY_SIZE) {
4188	ffe_ctl->index = 0;
4189	/*
4190	* We want to skip the LOOP_CACHING_WAIT step if we don't have
4191	* any uncached bgs and we've already done a full search
4192	* through.
4193	*/
4194	if (ffe_ctl->loop == LOOP_CACHING_NOWAIT &&
4195	(!ffe_ctl->orig_have_caching_bg && full_search))
4196	ffe_ctl->loop++;
4197	ffe_ctl->loop++;
4198
4199	if (ffe_ctl->loop == LOOP_ALLOC_CHUNK) {
4200	struct btrfs_trans_handle *trans;
4201	int exist = 0;
4202
4203	/* Check if allocation policy allows to create a new chunk */
4204	ret = can_allocate_chunk(fs_info, ffe_ctl);
4205	if (ret)
4206	return ret;
4207
4208	trans = current->journal_info;
4209	if (trans)
4210	exist = 1;
4211	else
4212	trans = btrfs_join_transaction(root);
4213
4214	if (IS_ERR(ptr: trans)) {
4215	ret = PTR_ERR(ptr: trans);
4216	return ret;
4217	}
4218
4219	ret = btrfs_chunk_alloc(trans, flags: ffe_ctl->flags,
4220	force: CHUNK_ALLOC_FORCE_FOR_EXTENT);
4221
4222	/* Do not bail out on ENOSPC since we can do more. */
4223	if (ret == -ENOSPC) {
4224	ret = 0;
4225	ffe_ctl->loop++;
4226	}
4227	else if (ret < 0)
4228	btrfs_abort_transaction(trans, ret);
4229	else
4230	ret = 0;
4231	if (!exist)
4232	btrfs_end_transaction(trans);
4233	if (ret)
4234	return ret;
4235	}
4236
4237	if (ffe_ctl->loop == LOOP_NO_EMPTY_SIZE) {
4238	if (ffe_ctl->policy != BTRFS_EXTENT_ALLOC_CLUSTERED)
4239	return -ENOSPC;
4240
4241	/*
4242	* Don't loop again if we already have no empty_size and
4243	* no empty_cluster.
4244	*/
4245	if (ffe_ctl->empty_size == 0 &&
4246	ffe_ctl->empty_cluster == 0)
4247	return -ENOSPC;
4248	ffe_ctl->empty_size = 0;
4249	ffe_ctl->empty_cluster = 0;
4250	}
4251	return 1;
4252	}
4253	return -ENOSPC;
4254	}
4255
4256	static bool find_free_extent_check_size_class(struct find_free_extent_ctl *ffe_ctl,
4257	struct btrfs_block_group *bg)
4258	{
4259	if (ffe_ctl->policy == BTRFS_EXTENT_ALLOC_ZONED)
4260	return true;
4261	if (!btrfs_block_group_should_use_size_class(bg))
4262	return true;
4263	if (ffe_ctl->loop >= LOOP_WRONG_SIZE_CLASS)
4264	return true;
4265	if (ffe_ctl->loop >= LOOP_UNSET_SIZE_CLASS &&
4266	bg->size_class == BTRFS_BG_SZ_NONE)
4267	return true;
4268	return ffe_ctl->size_class == bg->size_class;
4269	}
4270
4271	static int prepare_allocation_clustered(struct btrfs_fs_info *fs_info,
4272	struct find_free_extent_ctl *ffe_ctl,
4273	struct btrfs_space_info *space_info,
4274	struct btrfs_key *ins)
4275	{
4276	/*
4277	* If our free space is heavily fragmented we may not be able to make
4278	* big contiguous allocations, so instead of doing the expensive search
4279	* for free space, simply return ENOSPC with our max_extent_size so we
4280	* can go ahead and search for a more manageable chunk.
4281	*
4282	* If our max_extent_size is large enough for our allocation simply
4283	* disable clustering since we will likely not be able to find enough
4284	* space to create a cluster and induce latency trying.
4285	*/
4286	if (space_info->max_extent_size) {
4287	spin_lock(lock: &space_info->lock);
4288	if (space_info->max_extent_size &&
4289	ffe_ctl->num_bytes > space_info->max_extent_size) {
4290	ins->offset = space_info->max_extent_size;
4291	spin_unlock(lock: &space_info->lock);
4292	return -ENOSPC;
4293	} else if (space_info->max_extent_size) {
4294	ffe_ctl->use_cluster = false;
4295	}
4296	spin_unlock(lock: &space_info->lock);
4297	}
4298
4299	ffe_ctl->last_ptr = fetch_cluster_info(fs_info, space_info,
4300	empty_cluster: &ffe_ctl->empty_cluster);
4301	if (ffe_ctl->last_ptr) {
4302	struct btrfs_free_cluster *last_ptr = ffe_ctl->last_ptr;
4303
4304	spin_lock(lock: &last_ptr->lock);
4305	if (last_ptr->block_group)
4306	ffe_ctl->hint_byte = last_ptr->window_start;
4307	if (last_ptr->fragmented) {
4308	/*
4309	* We still set window_start so we can keep track of the
4310	* last place we found an allocation to try and save
4311	* some time.
4312	*/
4313	ffe_ctl->hint_byte = last_ptr->window_start;
4314	ffe_ctl->use_cluster = false;
4315	}
4316	spin_unlock(lock: &last_ptr->lock);
4317	}
4318
4319	return 0;
4320	}
4321
4322	static int prepare_allocation_zoned(struct btrfs_fs_info *fs_info,
4323	struct find_free_extent_ctl *ffe_ctl)
4324	{
4325	if (ffe_ctl->for_treelog) {
4326	spin_lock(lock: &fs_info->treelog_bg_lock);
4327	if (fs_info->treelog_bg)
4328	ffe_ctl->hint_byte = fs_info->treelog_bg;
4329	spin_unlock(lock: &fs_info->treelog_bg_lock);
4330	} else if (ffe_ctl->for_data_reloc) {
4331	spin_lock(lock: &fs_info->relocation_bg_lock);
4332	if (fs_info->data_reloc_bg)
4333	ffe_ctl->hint_byte = fs_info->data_reloc_bg;
4334	spin_unlock(lock: &fs_info->relocation_bg_lock);
4335	} else if (ffe_ctl->flags & BTRFS_BLOCK_GROUP_DATA) {
4336	struct btrfs_block_group *block_group;
4337
4338	spin_lock(lock: &fs_info->zone_active_bgs_lock);
4339	list_for_each_entry(block_group, &fs_info->zone_active_bgs, active_bg_list) {
4340	/*
4341	* No lock is OK here because avail is monotinically
4342	* decreasing, and this is just a hint.
4343	*/
4344	u64 avail = block_group->zone_capacity - block_group->alloc_offset;
4345
4346	if (block_group_bits(cache: block_group, bits: ffe_ctl->flags) &&
4347	avail >= ffe_ctl->num_bytes) {
4348	ffe_ctl->hint_byte = block_group->start;
4349	break;
4350	}
4351	}
4352	spin_unlock(lock: &fs_info->zone_active_bgs_lock);
4353	}
4354
4355	return 0;
4356	}
4357
4358	static int prepare_allocation(struct btrfs_fs_info *fs_info,
4359	struct find_free_extent_ctl *ffe_ctl,
4360	struct btrfs_space_info *space_info,
4361	struct btrfs_key *ins)
4362	{
4363	switch (ffe_ctl->policy) {
4364	case BTRFS_EXTENT_ALLOC_CLUSTERED:
4365	return prepare_allocation_clustered(fs_info, ffe_ctl,
4366	space_info, ins);
4367	case BTRFS_EXTENT_ALLOC_ZONED:
4368	return prepare_allocation_zoned(fs_info, ffe_ctl);
4369	default:
4370	BUG();
4371	}
4372	}
4373
4374	/*
4375	* walks the btree of allocated extents and find a hole of a given size.
4376	* The key ins is changed to record the hole:
4377	* ins->objectid == start position
4378	* ins->flags = BTRFS_EXTENT_ITEM_KEY
4379	* ins->offset == the size of the hole.
4380	* Any available blocks before search_start are skipped.
4381	*
4382	* If there is no suitable free space, we will record the max size of
4383	* the free space extent currently.
4384	*
4385	* The overall logic and call chain:
4386	*
4387	* find_free_extent()
4388	* |- Iterate through all block groups
4389	* | |- Get a valid block group
4390	* | |- Try to do clustered allocation in that block group
4391	* | |- Try to do unclustered allocation in that block group
4392	* | |- Check if the result is valid
4393	* | | |- If valid, then exit
4394	* | |- Jump to next block group
4395	* |
4396	* |- Push harder to find free extents
4397	* |- If not found, re-iterate all block groups
4398	*/
4399	static noinline int find_free_extent(struct btrfs_root *root,
4400	struct btrfs_key *ins,
4401	struct find_free_extent_ctl *ffe_ctl)
4402	{
4403	struct btrfs_fs_info *fs_info = root->fs_info;
4404	int ret = 0;
4405	int cache_block_group_error = 0;
4406	struct btrfs_block_group *block_group = NULL;
4407	struct btrfs_space_info *space_info;
4408	bool full_search = false;
4409
4410	WARN_ON(ffe_ctl->num_bytes < fs_info->sectorsize);
4411
4412	ffe_ctl->search_start = 0;
4413	/* For clustered allocation */
4414	ffe_ctl->empty_cluster = 0;
4415	ffe_ctl->last_ptr = NULL;
4416	ffe_ctl->use_cluster = true;
4417	ffe_ctl->have_caching_bg = false;
4418	ffe_ctl->orig_have_caching_bg = false;
4419	ffe_ctl->index = btrfs_bg_flags_to_raid_index(flags: ffe_ctl->flags);
4420	ffe_ctl->loop = 0;
4421	ffe_ctl->retry_uncached = false;
4422	ffe_ctl->cached = 0;
4423	ffe_ctl->max_extent_size = 0;
4424	ffe_ctl->total_free_space = 0;
4425	ffe_ctl->found_offset = 0;
4426	ffe_ctl->policy = BTRFS_EXTENT_ALLOC_CLUSTERED;
4427	ffe_ctl->size_class = btrfs_calc_block_group_size_class(size: ffe_ctl->num_bytes);
4428
4429	if (btrfs_is_zoned(fs_info))
4430	ffe_ctl->policy = BTRFS_EXTENT_ALLOC_ZONED;
4431
4432	ins->type = BTRFS_EXTENT_ITEM_KEY;
4433	ins->objectid = 0;
4434	ins->offset = 0;
4435
4436	trace_find_free_extent(root, ffe_ctl);
4437
4438	space_info = btrfs_find_space_info(info: fs_info, flags: ffe_ctl->flags);
4439	if (!space_info) {
4440	btrfs_err(fs_info, "No space info for %llu", ffe_ctl->flags);
4441	return -ENOSPC;
4442	}
4443
4444	ret = prepare_allocation(fs_info, ffe_ctl, space_info, ins);
4445	if (ret < 0)
4446	return ret;
4447
4448	ffe_ctl->search_start = max(ffe_ctl->search_start,
4449	first_logical_byte(fs_info));
4450	ffe_ctl->search_start = max(ffe_ctl->search_start, ffe_ctl->hint_byte);
4451	if (ffe_ctl->search_start == ffe_ctl->hint_byte) {
4452	block_group = btrfs_lookup_block_group(info: fs_info,
4453	bytenr: ffe_ctl->search_start);
4454	/*
4455	* we don't want to use the block group if it doesn't match our
4456	* allocation bits, or if its not cached.
4457	*
4458	* However if we are re-searching with an ideal block group
4459	* picked out then we don't care that the block group is cached.
4460	*/
4461	if (block_group && block_group_bits(cache: block_group, bits: ffe_ctl->flags) &&
4462	block_group->cached != BTRFS_CACHE_NO) {
4463	down_read(sem: &space_info->groups_sem);
4464	if (list_empty(head: &block_group->list) ||
4465	block_group->ro) {
4466	/*
4467	* someone is removing this block group,
4468	* we can't jump into the have_block_group
4469	* target because our list pointers are not
4470	* valid
4471	*/
4472	btrfs_put_block_group(cache: block_group);
4473	up_read(sem: &space_info->groups_sem);
4474	} else {
4475	ffe_ctl->index = btrfs_bg_flags_to_raid_index(
4476	flags: block_group->flags);
4477	btrfs_lock_block_group(cache: block_group,
4478	delalloc: ffe_ctl->delalloc);
4479	ffe_ctl->hinted = true;
4480	goto have_block_group;
4481	}
4482	} else if (block_group) {
4483	btrfs_put_block_group(cache: block_group);
4484	}
4485	}
4486	search:
4487	trace_find_free_extent_search_loop(root, ffe_ctl);
4488	ffe_ctl->have_caching_bg = false;
4489	if (ffe_ctl->index == btrfs_bg_flags_to_raid_index(flags: ffe_ctl->flags) ||
4490	ffe_ctl->index == 0)
4491	full_search = true;
4492	down_read(sem: &space_info->groups_sem);
4493	list_for_each_entry(block_group,
4494	&space_info->block_groups[ffe_ctl->index], list) {
4495	struct btrfs_block_group *bg_ret;
4496
4497	ffe_ctl->hinted = false;
4498	/* If the block group is read-only, we can skip it entirely. */
4499	if (unlikely(block_group->ro)) {
4500	if (ffe_ctl->for_treelog)
4501	btrfs_clear_treelog_bg(bg: block_group);
4502	if (ffe_ctl->for_data_reloc)
4503	btrfs_clear_data_reloc_bg(bg: block_group);
4504	continue;
4505	}
4506
4507	btrfs_grab_block_group(cache: block_group, delalloc: ffe_ctl->delalloc);
4508	ffe_ctl->search_start = block_group->start;
4509
4510	/*
4511	* this can happen if we end up cycling through all the
4512	* raid types, but we want to make sure we only allocate
4513	* for the proper type.
4514	*/
4515	if (!block_group_bits(cache: block_group, bits: ffe_ctl->flags)) {
4516	u64 extra = BTRFS_BLOCK_GROUP_DUP |
4517	BTRFS_BLOCK_GROUP_RAID1_MASK |
4518	BTRFS_BLOCK_GROUP_RAID56_MASK |
4519	BTRFS_BLOCK_GROUP_RAID10;
4520
4521	/*
4522	* if they asked for extra copies and this block group
4523	* doesn't provide them, bail. This does allow us to
4524	* fill raid0 from raid1.
4525	*/
4526	if ((ffe_ctl->flags & extra) && !(block_group->flags & extra))
4527	goto loop;
4528
4529	/*
4530	* This block group has different flags than we want.
4531	* It's possible that we have MIXED_GROUP flag but no
4532	* block group is mixed. Just skip such block group.
4533	*/
4534	btrfs_release_block_group(cache: block_group, delalloc: ffe_ctl->delalloc);
4535	continue;
4536	}
4537
4538	have_block_group:
4539	trace_find_free_extent_have_block_group(root, ffe_ctl, block_group);
4540	ffe_ctl->cached = btrfs_block_group_done(cache: block_group);
4541	if (unlikely(!ffe_ctl->cached)) {
4542	ffe_ctl->have_caching_bg = true;
4543	ret = btrfs_cache_block_group(cache: block_group, wait: false);
4544
4545	/*
4546	* If we get ENOMEM here or something else we want to
4547	* try other block groups, because it may not be fatal.
4548	* However if we can't find anything else we need to
4549	* save our return here so that we return the actual
4550	* error that caused problems, not ENOSPC.
4551	*/
4552	if (ret < 0) {
4553	if (!cache_block_group_error)
4554	cache_block_group_error = ret;
4555	ret = 0;
4556	goto loop;
4557	}
4558	ret = 0;
4559	}
4560
4561	if (unlikely(block_group->cached == BTRFS_CACHE_ERROR)) {
4562	if (!cache_block_group_error)
4563	cache_block_group_error = -EIO;
4564	goto loop;
4565	}
4566
4567	if (!find_free_extent_check_size_class(ffe_ctl, bg: block_group))
4568	goto loop;
4569
4570	bg_ret = NULL;
4571	ret = do_allocation(block_group, ffe_ctl, bg_ret: &bg_ret);
4572	if (ret > 0)
4573	goto loop;
4574
4575	if (bg_ret && bg_ret != block_group) {
4576	btrfs_release_block_group(cache: block_group, delalloc: ffe_ctl->delalloc);
4577	block_group = bg_ret;
4578	}
4579
4580	/* Checks */
4581	ffe_ctl->search_start = round_up(ffe_ctl->found_offset,
4582	fs_info->stripesize);
4583
4584	/* move on to the next group */
4585	if (ffe_ctl->search_start + ffe_ctl->num_bytes >
4586	block_group->start + block_group->length) {
4587	btrfs_add_free_space_unused(block_group,
4588	bytenr: ffe_ctl->found_offset,
4589	size: ffe_ctl->num_bytes);
4590	goto loop;
4591	}
4592
4593	if (ffe_ctl->found_offset < ffe_ctl->search_start)
4594	btrfs_add_free_space_unused(block_group,
4595	bytenr: ffe_ctl->found_offset,
4596	size: ffe_ctl->search_start - ffe_ctl->found_offset);
4597
4598	ret = btrfs_add_reserved_bytes(cache: block_group, ram_bytes: ffe_ctl->ram_bytes,
4599	num_bytes: ffe_ctl->num_bytes,
4600	delalloc: ffe_ctl->delalloc,
4601	force_wrong_size_class: ffe_ctl->loop >= LOOP_WRONG_SIZE_CLASS);
4602	if (ret == -EAGAIN) {
4603	btrfs_add_free_space_unused(block_group,
4604	bytenr: ffe_ctl->found_offset,
4605	size: ffe_ctl->num_bytes);
4606	goto loop;
4607	}
4608	btrfs_inc_block_group_reservations(bg: block_group);
4609
4610	/* we are all good, lets return */
4611	ins->objectid = ffe_ctl->search_start;
4612	ins->offset = ffe_ctl->num_bytes;
4613
4614	trace_btrfs_reserve_extent(block_group, ffe_ctl);
4615	btrfs_release_block_group(cache: block_group, delalloc: ffe_ctl->delalloc);
4616	break;
4617	loop:
4618	if (!ffe_ctl->cached && ffe_ctl->loop > LOOP_CACHING_NOWAIT &&
4619	!ffe_ctl->retry_uncached) {
4620	ffe_ctl->retry_uncached = true;
4621	btrfs_wait_block_group_cache_progress(cache: block_group,
4622	num_bytes: ffe_ctl->num_bytes +
4623	ffe_ctl->empty_cluster +
4624	ffe_ctl->empty_size);
4625	goto have_block_group;
4626	}
4627	release_block_group(block_group, ffe_ctl, delalloc: ffe_ctl->delalloc);
4628	cond_resched();
4629	}
4630	up_read(sem: &space_info->groups_sem);
4631
4632	ret = find_free_extent_update_loop(fs_info, ins, ffe_ctl, full_search);
4633	if (ret > 0)
4634	goto search;
4635
4636	if (ret == -ENOSPC && !cache_block_group_error) {
4637	/*
4638	* Use ffe_ctl->total_free_space as fallback if we can't find
4639	* any contiguous hole.
4640	*/
4641	if (!ffe_ctl->max_extent_size)
4642	ffe_ctl->max_extent_size = ffe_ctl->total_free_space;
4643	spin_lock(lock: &space_info->lock);
4644	space_info->max_extent_size = ffe_ctl->max_extent_size;
4645	spin_unlock(lock: &space_info->lock);
4646	ins->offset = ffe_ctl->max_extent_size;
4647	} else if (ret == -ENOSPC) {
4648	ret = cache_block_group_error;
4649	}
4650	return ret;
4651	}
4652
4653	/*
4654	* Entry point to the extent allocator. Tries to find a hole that is at least
4655	* as big as @num_bytes.
4656	*
4657	* @root - The root that will contain this extent
4658	*
4659	* @ram_bytes - The amount of space in ram that @num_bytes take. This
4660	* is used for accounting purposes. This value differs
4661	* from @num_bytes only in the case of compressed extents.
4662	*
4663	* @num_bytes - Number of bytes to allocate on-disk.
4664	*
4665	* @min_alloc_size - Indicates the minimum amount of space that the
4666	* allocator should try to satisfy. In some cases
4667	* @num_bytes may be larger than what is required and if
4668	* the filesystem is fragmented then allocation fails.
4669	* However, the presence of @min_alloc_size gives a
4670	* chance to try and satisfy the smaller allocation.
4671	*
4672	* @empty_size - A hint that you plan on doing more COW. This is the
4673	* size in bytes the allocator should try to find free
4674	* next to the block it returns. This is just a hint and
4675	* may be ignored by the allocator.
4676	*
4677	* @hint_byte - Hint to the allocator to start searching above the byte
4678	* address passed. It might be ignored.
4679	*
4680	* @ins - This key is modified to record the found hole. It will
4681	* have the following values:
4682	* ins->objectid == start position
4683	* ins->flags = BTRFS_EXTENT_ITEM_KEY
4684	* ins->offset == the size of the hole.
4685	*
4686	* @is_data - Boolean flag indicating whether an extent is
4687	* allocated for data (true) or metadata (false)
4688	*
4689	* @delalloc - Boolean flag indicating whether this allocation is for
4690	* delalloc or not. If 'true' data_rwsem of block groups
4691	* is going to be acquired.
4692	*
4693	*
4694	* Returns 0 when an allocation succeeded or < 0 when an error occurred. In
4695	* case -ENOSPC is returned then @ins->offset will contain the size of the
4696	* largest available hole the allocator managed to find.
4697	*/
4698	int btrfs_reserve_extent(struct btrfs_root *root, u64 ram_bytes,
4699	u64 num_bytes, u64 min_alloc_size,
4700	u64 empty_size, u64 hint_byte,
4701	struct btrfs_key *ins, int is_data, int delalloc)
4702	{
4703	struct btrfs_fs_info *fs_info = root->fs_info;
4704	struct find_free_extent_ctl ffe_ctl = {};
4705	bool final_tried = num_bytes == min_alloc_size;
4706	u64 flags;
4707	int ret;
4708	bool for_treelog = (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
4709	bool for_data_reloc = (btrfs_is_data_reloc_root(root) && is_data);
4710
4711	flags = get_alloc_profile_by_root(root, data: is_data);
4712	again:
4713	WARN_ON(num_bytes < fs_info->sectorsize);
4714
4715	ffe_ctl.ram_bytes = ram_bytes;
4716	ffe_ctl.num_bytes = num_bytes;
4717	ffe_ctl.min_alloc_size = min_alloc_size;
4718	ffe_ctl.empty_size = empty_size;
4719	ffe_ctl.flags = flags;
4720	ffe_ctl.delalloc = delalloc;
4721	ffe_ctl.hint_byte = hint_byte;
4722	ffe_ctl.for_treelog = for_treelog;
4723	ffe_ctl.for_data_reloc = for_data_reloc;
4724
4725	ret = find_free_extent(root, ins, ffe_ctl: &ffe_ctl);
4726	if (!ret && !is_data) {
4727	btrfs_dec_block_group_reservations(fs_info, start: ins->objectid);
4728	} else if (ret == -ENOSPC) {
4729	if (!final_tried && ins->offset) {
4730	num_bytes = min(num_bytes >> 1, ins->offset);
4731	num_bytes = round_down(num_bytes,
4732	fs_info->sectorsize);
4733	num_bytes = max(num_bytes, min_alloc_size);
4734	ram_bytes = num_bytes;
4735	if (num_bytes == min_alloc_size)
4736	final_tried = true;
4737	goto again;
4738	} else if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
4739	struct btrfs_space_info *sinfo;
4740
4741	sinfo = btrfs_find_space_info(info: fs_info, flags);
4742	btrfs_err(fs_info,
4743	"allocation failed flags %llu, wanted %llu tree-log %d, relocation: %d",
4744	flags, num_bytes, for_treelog, for_data_reloc);
4745	if (sinfo)
4746	btrfs_dump_space_info(fs_info, info: sinfo,
4747	bytes: num_bytes, dump_block_groups: 1);
4748	}
4749	}
4750
4751	return ret;
4752	}
4753
4754	int btrfs_free_reserved_extent(struct btrfs_fs_info *fs_info,
4755	u64 start, u64 len, int delalloc)
4756	{
4757	struct btrfs_block_group *cache;
4758
4759	cache = btrfs_lookup_block_group(info: fs_info, bytenr: start);
4760	if (!cache) {
4761	btrfs_err(fs_info, "Unable to find block group for %llu",
4762	start);
4763	return -ENOSPC;
4764	}
4765
4766	btrfs_add_free_space(block_group: cache, bytenr: start, size: len);
4767	btrfs_free_reserved_bytes(cache, num_bytes: len, delalloc);
4768	trace_btrfs_reserved_extent_free(fs_info, start, len);
4769
4770	btrfs_put_block_group(cache);
4771	return 0;
4772	}
4773
4774	int btrfs_pin_reserved_extent(struct btrfs_trans_handle *trans,
4775	const struct extent_buffer *eb)
4776	{
4777	struct btrfs_block_group *cache;
4778	int ret = 0;
4779
4780	cache = btrfs_lookup_block_group(info: trans->fs_info, bytenr: eb->start);
4781	if (!cache) {
4782	btrfs_err(trans->fs_info, "unable to find block group for %llu",
4783	eb->start);
4784	return -ENOSPC;
4785	}
4786
4787	ret = pin_down_extent(trans, cache, bytenr: eb->start, num_bytes: eb->len, reserved: 1);
4788	btrfs_put_block_group(cache);
4789	return ret;
4790	}
4791
4792	static int alloc_reserved_extent(struct btrfs_trans_handle *trans, u64 bytenr,
4793	u64 num_bytes)
4794	{
4795	struct btrfs_fs_info *fs_info = trans->fs_info;
4796	int ret;
4797
4798	ret = remove_from_free_space_tree(trans, start: bytenr, size: num_bytes);
4799	if (ret)
4800	return ret;
4801
4802	ret = btrfs_update_block_group(trans, bytenr, num_bytes, alloc: true);
4803	if (ret) {
4804	ASSERT(!ret);
4805	btrfs_err(fs_info, "update block group failed for %llu %llu",
4806	bytenr, num_bytes);
4807	return ret;
4808	}
4809
4810	trace_btrfs_reserved_extent_alloc(fs_info, start: bytenr, len: num_bytes);
4811	return 0;
4812	}
4813
4814	static int alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
4815	u64 parent, u64 root_objectid,
4816	u64 flags, u64 owner, u64 offset,
4817	struct btrfs_key *ins, int ref_mod, u64 oref_root)
4818	{
4819	struct btrfs_fs_info *fs_info = trans->fs_info;
4820	struct btrfs_root *extent_root;
4821	int ret;
4822	struct btrfs_extent_item *extent_item;
4823	struct btrfs_extent_owner_ref *oref;
4824	struct btrfs_extent_inline_ref *iref;
4825	struct btrfs_path *path;
4826	struct extent_buffer *leaf;
4827	int type;
4828	u32 size;
4829	const bool simple_quota = (btrfs_qgroup_mode(fs_info) == BTRFS_QGROUP_MODE_SIMPLE);
4830
4831	if (parent > 0)
4832	type = BTRFS_SHARED_DATA_REF_KEY;
4833	else
4834	type = BTRFS_EXTENT_DATA_REF_KEY;
4835
4836	size = sizeof(*extent_item);
4837	if (simple_quota)
4838	size += btrfs_extent_inline_ref_size(BTRFS_EXTENT_OWNER_REF_KEY);
4839	size += btrfs_extent_inline_ref_size(type);
4840
4841	path = btrfs_alloc_path();
4842	if (!path)
4843	return -ENOMEM;
4844
4845	extent_root = btrfs_extent_root(fs_info, bytenr: ins->objectid);
4846	ret = btrfs_insert_empty_item(trans, root: extent_root, path, key: ins, data_size: size);
4847	if (ret) {
4848	btrfs_free_path(p: path);
4849	return ret;
4850	}
4851
4852	leaf = path->nodes[0];
4853	extent_item = btrfs_item_ptr(leaf, path->slots[0],
4854	struct btrfs_extent_item);
4855	btrfs_set_extent_refs(eb: leaf, s: extent_item, val: ref_mod);
4856	btrfs_set_extent_generation(eb: leaf, s: extent_item, val: trans->transid);
4857	btrfs_set_extent_flags(eb: leaf, s: extent_item,
4858	val: flags | BTRFS_EXTENT_FLAG_DATA);
4859
4860	iref = (struct btrfs_extent_inline_ref *)(extent_item + 1);
4861	if (simple_quota) {
4862	btrfs_set_extent_inline_ref_type(eb: leaf, s: iref, BTRFS_EXTENT_OWNER_REF_KEY);
4863	oref = (struct btrfs_extent_owner_ref *)(&iref->offset);
4864	btrfs_set_extent_owner_ref_root_id(eb: leaf, s: oref, val: oref_root);
4865	iref = (struct btrfs_extent_inline_ref *)(oref + 1);
4866	}
4867	btrfs_set_extent_inline_ref_type(eb: leaf, s: iref, val: type);
4868
4869	if (parent > 0) {
4870	struct btrfs_shared_data_ref *ref;
4871	ref = (struct btrfs_shared_data_ref *)(iref + 1);
4872	btrfs_set_extent_inline_ref_offset(eb: leaf, s: iref, val: parent);
4873	btrfs_set_shared_data_ref_count(eb: leaf, s: ref, val: ref_mod);
4874	} else {
4875	struct btrfs_extent_data_ref *ref;
4876	ref = (struct btrfs_extent_data_ref *)(&iref->offset);
4877	btrfs_set_extent_data_ref_root(eb: leaf, s: ref, val: root_objectid);
4878	btrfs_set_extent_data_ref_objectid(eb: leaf, s: ref, val: owner);
4879	btrfs_set_extent_data_ref_offset(eb: leaf, s: ref, val: offset);
4880	btrfs_set_extent_data_ref_count(eb: leaf, s: ref, val: ref_mod);
4881	}
4882
4883	btrfs_mark_buffer_dirty(trans, buf: path->nodes[0]);
4884	btrfs_free_path(p: path);
4885
4886	return alloc_reserved_extent(trans, bytenr: ins->objectid, num_bytes: ins->offset);
4887	}
4888
4889	static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
4890	struct btrfs_delayed_ref_node *node,
4891	struct btrfs_delayed_extent_op *extent_op)
4892	{
4893	struct btrfs_fs_info *fs_info = trans->fs_info;
4894	struct btrfs_root *extent_root;
4895	int ret;
4896	struct btrfs_extent_item *extent_item;
4897	struct btrfs_key extent_key;
4898	struct btrfs_tree_block_info *block_info;
4899	struct btrfs_extent_inline_ref *iref;
4900	struct btrfs_path *path;
4901	struct extent_buffer *leaf;
4902	struct btrfs_delayed_tree_ref *ref;
4903	u32 size = sizeof(*extent_item) + sizeof(*iref);
4904	u64 flags = extent_op->flags_to_set;
4905	bool skinny_metadata = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
4906
4907	ref = btrfs_delayed_node_to_tree_ref(node);
4908
4909	extent_key.objectid = node->bytenr;
4910	if (skinny_metadata) {
4911	extent_key.offset = ref->level;
4912	extent_key.type = BTRFS_METADATA_ITEM_KEY;
4913	} else {
4914	extent_key.offset = node->num_bytes;
4915	extent_key.type = BTRFS_EXTENT_ITEM_KEY;
4916	size += sizeof(*block_info);
4917	}
4918
4919	path = btrfs_alloc_path();
4920	if (!path)
4921	return -ENOMEM;
4922
4923	extent_root = btrfs_extent_root(fs_info, bytenr: extent_key.objectid);
4924	ret = btrfs_insert_empty_item(trans, root: extent_root, path, key: &extent_key,
4925	data_size: size);
4926	if (ret) {
4927	btrfs_free_path(p: path);
4928	return ret;
4929	}
4930
4931	leaf = path->nodes[0];
4932	extent_item = btrfs_item_ptr(leaf, path->slots[0],
4933	struct btrfs_extent_item);
4934	btrfs_set_extent_refs(eb: leaf, s: extent_item, val: 1);
4935	btrfs_set_extent_generation(eb: leaf, s: extent_item, val: trans->transid);
4936	btrfs_set_extent_flags(eb: leaf, s: extent_item,
4937	val: flags | BTRFS_EXTENT_FLAG_TREE_BLOCK);
4938
4939	if (skinny_metadata) {
4940	iref = (struct btrfs_extent_inline_ref *)(extent_item + 1);
4941	} else {
4942	block_info = (struct btrfs_tree_block_info *)(extent_item + 1);
4943	btrfs_set_tree_block_key(eb: leaf, item: block_info, key: &extent_op->key);
4944	btrfs_set_tree_block_level(eb: leaf, s: block_info, val: ref->level);
4945	iref = (struct btrfs_extent_inline_ref *)(block_info + 1);
4946	}
4947
4948	if (node->type == BTRFS_SHARED_BLOCK_REF_KEY) {
4949	btrfs_set_extent_inline_ref_type(eb: leaf, s: iref,
4950	BTRFS_SHARED_BLOCK_REF_KEY);
4951	btrfs_set_extent_inline_ref_offset(eb: leaf, s: iref, val: ref->parent);
4952	} else {
4953	btrfs_set_extent_inline_ref_type(eb: leaf, s: iref,
4954	BTRFS_TREE_BLOCK_REF_KEY);
4955	btrfs_set_extent_inline_ref_offset(eb: leaf, s: iref, val: ref->root);
4956	}
4957
4958	btrfs_mark_buffer_dirty(trans, buf: leaf);
4959	btrfs_free_path(p: path);
4960
4961	return alloc_reserved_extent(trans, bytenr: node->bytenr, num_bytes: fs_info->nodesize);
4962	}
4963
4964	int btrfs_alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
4965	struct btrfs_root *root, u64 owner,
4966	u64 offset, u64 ram_bytes,
4967	struct btrfs_key *ins)
4968	{
4969	struct btrfs_ref generic_ref = { 0 };
4970	u64 root_objectid = root->root_key.objectid;
4971	u64 owning_root = root_objectid;
4972
4973	ASSERT(root_objectid != BTRFS_TREE_LOG_OBJECTID);
4974
4975	if (btrfs_is_data_reloc_root(root) && is_fstree(rootid: root->relocation_src_root))
4976	owning_root = root->relocation_src_root;
4977
4978	btrfs_init_generic_ref(generic_ref: &generic_ref, action: BTRFS_ADD_DELAYED_EXTENT,
4979	bytenr: ins->objectid, len: ins->offset, parent: 0, owning_root);
4980	btrfs_init_data_ref(generic_ref: &generic_ref, ref_root: root_objectid, ino: owner,
4981	offset, mod_root: 0, skip_qgroup: false);
4982	btrfs_ref_tree_mod(fs_info: root->fs_info, generic_ref: &generic_ref);
4983
4984	return btrfs_add_delayed_data_ref(trans, generic_ref: &generic_ref, reserved: ram_bytes);
4985	}
4986
4987	/*
4988	* this is used by the tree logging recovery code. It records that
4989	* an extent has been allocated and makes sure to clear the free
4990	* space cache bits as well
4991	*/
4992	int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans,
4993	u64 root_objectid, u64 owner, u64 offset,
4994	struct btrfs_key *ins)
4995	{
4996	struct btrfs_fs_info *fs_info = trans->fs_info;
4997	int ret;
4998	struct btrfs_block_group *block_group;
4999	struct btrfs_space_info *space_info;
5000	struct btrfs_squota_delta delta = {
5001	.root = root_objectid,
5002	.num_bytes = ins->offset,
5003	.generation = trans->transid,
5004	.is_data = true,
5005	.is_inc = true,
5006	};
5007
5008	/*
5009	* Mixed block groups will exclude before processing the log so we only
5010	* need to do the exclude dance if this fs isn't mixed.
5011	*/
5012	if (!btrfs_fs_incompat(fs_info, MIXED_GROUPS)) {
5013	ret = __exclude_logged_extent(fs_info, start: ins->objectid,
5014	num_bytes: ins->offset);
5015	if (ret)
5016	return ret;
5017	}
5018
5019	block_group = btrfs_lookup_block_group(info: fs_info, bytenr: ins->objectid);
5020	if (!block_group)
5021	return -EINVAL;
5022
5023	space_info = block_group->space_info;
5024	spin_lock(lock: &space_info->lock);
5025	spin_lock(lock: &block_group->lock);
5026	space_info->bytes_reserved += ins->offset;
5027	block_group->reserved += ins->offset;
5028	spin_unlock(lock: &block_group->lock);
5029	spin_unlock(lock: &space_info->lock);
5030
5031	ret = alloc_reserved_file_extent(trans, parent: 0, root_objectid, flags: 0, owner,
5032	offset, ins, ref_mod: 1, oref_root: root_objectid);
5033	if (ret)
5034	btrfs_pin_extent(trans, bytenr: ins->objectid, num_bytes: ins->offset, reserved: 1);
5035	ret = btrfs_record_squota_delta(fs_info, delta: &delta);
5036	btrfs_put_block_group(cache: block_group);
5037	return ret;
5038	}
5039
5040	#ifdef CONFIG_BTRFS_DEBUG
5041	/*
5042	* Extra safety check in case the extent tree is corrupted and extent allocator
5043	* chooses to use a tree block which is already used and locked.
5044	*/
5045	static bool check_eb_lock_owner(const struct extent_buffer *eb)
5046	{
5047	if (eb->lock_owner == current->pid) {
5048	btrfs_err_rl(eb->fs_info,
5049	"tree block %llu owner %llu already locked by pid=%d, extent tree corruption detected",
5050	eb->start, btrfs_header_owner(eb), current->pid);
5051	return true;
5052	}
5053	return false;
5054	}
5055	#else
5056	static bool check_eb_lock_owner(struct extent_buffer *eb)
5057	{
5058	return false;
5059	}
5060	#endif
5061
5062	static struct extent_buffer *
5063	btrfs_init_new_buffer(struct btrfs_trans_handle *trans, struct btrfs_root *root,
5064	u64 bytenr, int level, u64 owner,
5065	enum btrfs_lock_nesting nest)
5066	{
5067	struct btrfs_fs_info *fs_info = root->fs_info;
5068	struct extent_buffer *buf;
5069	u64 lockdep_owner = owner;
5070
5071	buf = btrfs_find_create_tree_block(fs_info, bytenr, owner_root: owner, level);
5072	if (IS_ERR(ptr: buf))
5073	return buf;
5074
5075	if (check_eb_lock_owner(eb: buf)) {
5076	free_extent_buffer(eb: buf);
5077	return ERR_PTR(error: -EUCLEAN);
5078	}
5079
5080	/*
5081	* The reloc trees are just snapshots, so we need them to appear to be
5082	* just like any other fs tree WRT lockdep.
5083	*
5084	* The exception however is in replace_path() in relocation, where we
5085	* hold the lock on the original fs root and then search for the reloc
5086	* root. At that point we need to make sure any reloc root buffers are
5087	* set to the BTRFS_TREE_RELOC_OBJECTID lockdep class in order to make
5088	* lockdep happy.
5089	*/
5090	if (lockdep_owner == BTRFS_TREE_RELOC_OBJECTID &&
5091	!test_bit(BTRFS_ROOT_RESET_LOCKDEP_CLASS, &root->state))
5092	lockdep_owner = BTRFS_FS_TREE_OBJECTID;
5093
5094	/* btrfs_clear_buffer_dirty() accesses generation field. */
5095	btrfs_set_header_generation(eb: buf, val: trans->transid);
5096
5097	/*
5098	* This needs to stay, because we could allocate a freed block from an
5099	* old tree into a new tree, so we need to make sure this new block is
5100	* set to the appropriate level and owner.
5101	*/
5102	btrfs_set_buffer_lockdep_class(objectid: lockdep_owner, eb: buf, level);
5103
5104	__btrfs_tree_lock(eb: buf, nest);
5105	btrfs_clear_buffer_dirty(trans, buf);
5106	clear_bit(nr: EXTENT_BUFFER_STALE, addr: &buf->bflags);
5107	clear_bit(nr: EXTENT_BUFFER_ZONED_ZEROOUT, addr: &buf->bflags);
5108
5109	set_extent_buffer_uptodate(buf);
5110
5111	memzero_extent_buffer(eb: buf, start: 0, len: sizeof(struct btrfs_header));
5112	btrfs_set_header_level(eb: buf, val: level);
5113	btrfs_set_header_bytenr(eb: buf, val: buf->start);
5114	btrfs_set_header_generation(eb: buf, val: trans->transid);
5115	btrfs_set_header_backref_rev(eb: buf, BTRFS_MIXED_BACKREF_REV);
5116	btrfs_set_header_owner(eb: buf, val: owner);
5117	write_extent_buffer_fsid(eb: buf, fsid: fs_info->fs_devices->metadata_uuid);
5118	write_extent_buffer_chunk_tree_uuid(eb: buf, chunk_tree_uuid: fs_info->chunk_tree_uuid);
5119	if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) {
5120	buf->log_index = root->log_transid % 2;
5121	/*
5122	* we allow two log transactions at a time, use different
5123	* EXTENT bit to differentiate dirty pages.
5124	*/
5125	if (buf->log_index == 0)
5126	set_extent_bit(tree: &root->dirty_log_pages, start: buf->start,
5127	end: buf->start + buf->len - 1,
5128	bits: EXTENT_DIRTY, NULL);
5129	else
5130	set_extent_bit(tree: &root->dirty_log_pages, start: buf->start,
5131	end: buf->start + buf->len - 1,
5132	bits: EXTENT_NEW, NULL);
5133	} else {
5134	buf->log_index = -1;
5135	set_extent_bit(tree: &trans->transaction->dirty_pages, start: buf->start,
5136	end: buf->start + buf->len - 1, bits: EXTENT_DIRTY, NULL);
5137	}
5138	/* this returns a buffer locked for blocking */
5139	return buf;
5140	}
5141
5142	/*
5143	* finds a free extent and does all the dirty work required for allocation
5144	* returns the tree buffer or an ERR_PTR on error.
5145	*/
5146	struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
5147	struct btrfs_root *root,
5148	u64 parent, u64 root_objectid,
5149	const struct btrfs_disk_key *key,
5150	int level, u64 hint,
5151	u64 empty_size,
5152	u64 reloc_src_root,
5153	enum btrfs_lock_nesting nest)
5154	{
5155	struct btrfs_fs_info *fs_info = root->fs_info;
5156	struct btrfs_key ins;
5157	struct btrfs_block_rsv *block_rsv;
5158	struct extent_buffer *buf;
5159	struct btrfs_delayed_extent_op *extent_op;
5160	struct btrfs_ref generic_ref = { 0 };
5161	u64 flags = 0;
5162	int ret;
5163	u32 blocksize = fs_info->nodesize;
5164	bool skinny_metadata = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
5165	u64 owning_root;
5166
5167	#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
5168	if (btrfs_is_testing(fs_info)) {
5169	buf = btrfs_init_new_buffer(trans, root, bytenr: root->alloc_bytenr,
5170	level, owner: root_objectid, nest);
5171	if (!IS_ERR(ptr: buf))
5172	root->alloc_bytenr += blocksize;
5173	return buf;
5174	}
5175	#endif
5176
5177	block_rsv = btrfs_use_block_rsv(trans, root, blocksize);
5178	if (IS_ERR(ptr: block_rsv))
5179	return ERR_CAST(ptr: block_rsv);
5180
5181	ret = btrfs_reserve_extent(root, ram_bytes: blocksize, num_bytes: blocksize, min_alloc_size: blocksize,
5182	empty_size, hint_byte: hint, ins: &ins, is_data: 0, delalloc: 0);
5183	if (ret)
5184	goto out_unuse;
5185
5186	buf = btrfs_init_new_buffer(trans, root, bytenr: ins.objectid, level,
5187	owner: root_objectid, nest);
5188	if (IS_ERR(ptr: buf)) {
5189	ret = PTR_ERR(ptr: buf);
5190	goto out_free_reserved;
5191	}
5192	owning_root = btrfs_header_owner(eb: buf);
5193
5194	if (root_objectid == BTRFS_TREE_RELOC_OBJECTID) {
5195	if (parent == 0)
5196	parent = ins.objectid;
5197	flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
5198	owning_root = reloc_src_root;
5199	} else
5200	BUG_ON(parent > 0);
5201
5202	if (root_objectid != BTRFS_TREE_LOG_OBJECTID) {
5203	extent_op = btrfs_alloc_delayed_extent_op();
5204	if (!extent_op) {
5205	ret = -ENOMEM;
5206	goto out_free_buf;
5207	}
5208	if (key)
5209	memcpy(&extent_op->key, key, sizeof(extent_op->key));
5210	else
5211	memset(&extent_op->key, 0, sizeof(extent_op->key));
5212	extent_op->flags_to_set = flags;
5213	extent_op->update_key = skinny_metadata ? false : true;
5214	extent_op->update_flags = true;
5215	extent_op->level = level;
5216
5217	btrfs_init_generic_ref(generic_ref: &generic_ref, action: BTRFS_ADD_DELAYED_EXTENT,
5218	bytenr: ins.objectid, len: ins.offset, parent, owning_root);
5219	btrfs_init_tree_ref(generic_ref: &generic_ref, level, root: root_objectid,
5220	mod_root: root->root_key.objectid, skip_qgroup: false);
5221	btrfs_ref_tree_mod(fs_info, generic_ref: &generic_ref);
5222	ret = btrfs_add_delayed_tree_ref(trans, generic_ref: &generic_ref, extent_op);
5223	if (ret)
5224	goto out_free_delayed;
5225	}
5226	return buf;
5227
5228	out_free_delayed:
5229	btrfs_free_delayed_extent_op(op: extent_op);
5230	out_free_buf:
5231	btrfs_tree_unlock(eb: buf);
5232	free_extent_buffer(eb: buf);
5233	out_free_reserved:
5234	btrfs_free_reserved_extent(fs_info, start: ins.objectid, len: ins.offset, delalloc: 0);
5235	out_unuse:
5236	btrfs_unuse_block_rsv(fs_info, block_rsv, blocksize);
5237	return ERR_PTR(error: ret);
5238	}
5239
5240	struct walk_control {
5241	u64 refs[BTRFS_MAX_LEVEL];
5242	u64 flags[BTRFS_MAX_LEVEL];
5243	struct btrfs_key update_progress;
5244	struct btrfs_key drop_progress;
5245	int drop_level;
5246	int stage;
5247	int level;
5248	int shared_level;
5249	int update_ref;
5250	int keep_locks;
5251	int reada_slot;
5252	int reada_count;
5253	int restarted;
5254	};
5255
5256	#define DROP_REFERENCE 1
5257	#define UPDATE_BACKREF 2
5258
5259	static noinline void reada_walk_down(struct btrfs_trans_handle *trans,
5260	struct btrfs_root *root,
5261	struct walk_control *wc,
5262	struct btrfs_path *path)
5263	{
5264	struct btrfs_fs_info *fs_info = root->fs_info;
5265	u64 bytenr;
5266	u64 generation;
5267	u64 refs;
5268	u64 flags;
5269	u32 nritems;
5270	struct btrfs_key key;
5271	struct extent_buffer *eb;
5272	int ret;
5273	int slot;
5274	int nread = 0;
5275
5276	if (path->slots[wc->level] < wc->reada_slot) {
5277	wc->reada_count = wc->reada_count * 2 / 3;
5278	wc->reada_count = max(wc->reada_count, 2);
5279	} else {
5280	wc->reada_count = wc->reada_count * 3 / 2;
5281	wc->reada_count = min_t(int, wc->reada_count,
5282	BTRFS_NODEPTRS_PER_BLOCK(fs_info));
5283	}
5284
5285	eb = path->nodes[wc->level];
5286	nritems = btrfs_header_nritems(eb);
5287
5288	for (slot = path->slots[wc->level]; slot < nritems; slot++) {
5289	if (nread >= wc->reada_count)
5290	break;
5291
5292	cond_resched();
5293	bytenr = btrfs_node_blockptr(eb, nr: slot);
5294	generation = btrfs_node_ptr_generation(eb, nr: slot);
5295
5296	if (slot == path->slots[wc->level])
5297	goto reada;
5298
5299	if (wc->stage == UPDATE_BACKREF &&
5300	generation <= root->root_key.offset)
5301	continue;
5302
5303	/* We don't lock the tree block, it's OK to be racy here */
5304	ret = btrfs_lookup_extent_info(trans, fs_info, bytenr,
5305	offset: wc->level - 1, metadata: 1, refs: &refs,
5306	flags: &flags, NULL);
5307	/* We don't care about errors in readahead. */
5308	if (ret < 0)
5309	continue;
5310	BUG_ON(refs == 0);
5311
5312	if (wc->stage == DROP_REFERENCE) {
5313	if (refs == 1)
5314	goto reada;
5315
5316	if (wc->level == 1 &&
5317	(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
5318	continue;
5319	if (!wc->update_ref ||
5320	generation <= root->root_key.offset)
5321	continue;
5322	btrfs_node_key_to_cpu(eb, cpu_key: &key, nr: slot);
5323	ret = btrfs_comp_cpu_keys(k1: &key,
5324	k2: &wc->update_progress);
5325	if (ret < 0)
5326	continue;
5327	} else {
5328	if (wc->level == 1 &&
5329	(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
5330	continue;
5331	}
5332	reada:
5333	btrfs_readahead_node_child(node: eb, slot);
5334	nread++;
5335	}
5336	wc->reada_slot = slot;
5337	}
5338
5339	/*
5340	* helper to process tree block while walking down the tree.
5341	*
5342	* when wc->stage == UPDATE_BACKREF, this function updates
5343	* back refs for pointers in the block.
5344	*
5345	* NOTE: return value 1 means we should stop walking down.
5346	*/
5347	static noinline int walk_down_proc(struct btrfs_trans_handle *trans,
5348	struct btrfs_root *root,
5349	struct btrfs_path *path,
5350	struct walk_control *wc, int lookup_info)
5351	{
5352	struct btrfs_fs_info *fs_info = root->fs_info;
5353	int level = wc->level;
5354	struct extent_buffer *eb = path->nodes[level];
5355	u64 flag = BTRFS_BLOCK_FLAG_FULL_BACKREF;
5356	int ret;
5357
5358	if (wc->stage == UPDATE_BACKREF &&
5359	btrfs_header_owner(eb) != root->root_key.objectid)
5360	return 1;
5361
5362	/*
5363	* when reference count of tree block is 1, it won't increase
5364	* again. once full backref flag is set, we never clear it.
5365	*/
5366	if (lookup_info &&
5367	((wc->stage == DROP_REFERENCE && wc->refs[level] != 1) ||
5368	(wc->stage == UPDATE_BACKREF && !(wc->flags[level] & flag)))) {
5369	BUG_ON(!path->locks[level]);
5370	ret = btrfs_lookup_extent_info(trans, fs_info,
5371	bytenr: eb->start, offset: level, metadata: 1,
5372	refs: &wc->refs[level],
5373	flags: &wc->flags[level],
5374	NULL);
5375	BUG_ON(ret == -ENOMEM);
5376	if (ret)
5377	return ret;
5378	BUG_ON(wc->refs[level] == 0);
5379	}
5380
5381	if (wc->stage == DROP_REFERENCE) {
5382	if (wc->refs[level] > 1)
5383	return 1;
5384
5385	if (path->locks[level] && !wc->keep_locks) {
5386	btrfs_tree_unlock_rw(eb, rw: path->locks[level]);
5387	path->locks[level] = 0;
5388	}
5389	return 0;
5390	}
5391
5392	/* wc->stage == UPDATE_BACKREF */
5393	if (!(wc->flags[level] & flag)) {
5394	BUG_ON(!path->locks[level]);
5395	ret = btrfs_inc_ref(trans, root, buf: eb, full_backref: 1);
5396	BUG_ON(ret); /* -ENOMEM */
5397	ret = btrfs_dec_ref(trans, root, buf: eb, full_backref: 0);
5398	BUG_ON(ret); /* -ENOMEM */
5399	ret = btrfs_set_disk_extent_flags(trans, eb, flags: flag);
5400	BUG_ON(ret); /* -ENOMEM */
5401	wc->flags[level] |= flag;
5402	}
5403
5404	/*
5405	* the block is shared by multiple trees, so it's not good to
5406	* keep the tree lock
5407	*/
5408	if (path->locks[level] && level > 0) {
5409	btrfs_tree_unlock_rw(eb, rw: path->locks[level]);
5410	path->locks[level] = 0;
5411	}
5412	return 0;
5413	}
5414
5415	/*
5416	* This is used to verify a ref exists for this root to deal with a bug where we
5417	* would have a drop_progress key that hadn't been updated properly.
5418	*/
5419	static int check_ref_exists(struct btrfs_trans_handle *trans,
5420	struct btrfs_root *root, u64 bytenr, u64 parent,
5421	int level)
5422	{
5423	struct btrfs_path *path;
5424	struct btrfs_extent_inline_ref *iref;
5425	int ret;
5426
5427	path = btrfs_alloc_path();
5428	if (!path)
5429	return -ENOMEM;
5430
5431	ret = lookup_extent_backref(trans, path, ref_ret: &iref, bytenr,
5432	num_bytes: root->fs_info->nodesize, parent,
5433	root_objectid: root->root_key.objectid, owner: level, offset: 0);
5434	btrfs_free_path(p: path);
5435	if (ret == -ENOENT)
5436	return 0;
5437	if (ret < 0)
5438	return ret;
5439	return 1;
5440	}
5441
5442	/*
5443	* helper to process tree block pointer.
5444	*
5445	* when wc->stage == DROP_REFERENCE, this function checks
5446	* reference count of the block pointed to. if the block
5447	* is shared and we need update back refs for the subtree
5448	* rooted at the block, this function changes wc->stage to
5449	* UPDATE_BACKREF. if the block is shared and there is no
5450	* need to update back, this function drops the reference
5451	* to the block.
5452	*
5453	* NOTE: return value 1 means we should stop walking down.
5454	*/
5455	static noinline int do_walk_down(struct btrfs_trans_handle *trans,
5456	struct btrfs_root *root,
5457	struct btrfs_path *path,
5458	struct walk_control *wc, int *lookup_info)
5459	{
5460	struct btrfs_fs_info *fs_info = root->fs_info;
5461	u64 bytenr;
5462	u64 generation;
5463	u64 parent;
5464	u64 owner_root = 0;
5465	struct btrfs_tree_parent_check check = { 0 };
5466	struct btrfs_key key;
5467	struct btrfs_ref ref = { 0 };
5468	struct extent_buffer *next;
5469	int level = wc->level;
5470	int reada = 0;
5471	int ret = 0;
5472	bool need_account = false;
5473
5474	generation = btrfs_node_ptr_generation(eb: path->nodes[level],
5475	nr: path->slots[level]);
5476	/*
5477	* if the lower level block was created before the snapshot
5478	* was created, we know there is no need to update back refs
5479	* for the subtree
5480	*/
5481	if (wc->stage == UPDATE_BACKREF &&
5482	generation <= root->root_key.offset) {
5483	*lookup_info = 1;
5484	return 1;
5485	}
5486
5487	bytenr = btrfs_node_blockptr(eb: path->nodes[level], nr: path->slots[level]);
5488
5489	check.level = level - 1;
5490	check.transid = generation;
5491	check.owner_root = root->root_key.objectid;
5492	check.has_first_key = true;
5493	btrfs_node_key_to_cpu(eb: path->nodes[level], cpu_key: &check.first_key,
5494	nr: path->slots[level]);
5495
5496	next = find_extent_buffer(fs_info, start: bytenr);
5497	if (!next) {
5498	next = btrfs_find_create_tree_block(fs_info, bytenr,
5499	owner_root: root->root_key.objectid, level: level - 1);
5500	if (IS_ERR(ptr: next))
5501	return PTR_ERR(ptr: next);
5502	reada = 1;
5503	}
5504	btrfs_tree_lock(eb: next);
5505
5506	ret = btrfs_lookup_extent_info(trans, fs_info, bytenr, offset: level - 1, metadata: 1,
5507	refs: &wc->refs[level - 1],
5508	flags: &wc->flags[level - 1],
5509	owning_root: &owner_root);
5510	if (ret < 0)
5511	goto out_unlock;
5512
5513	if (unlikely(wc->refs[level - 1] == 0)) {
5514	btrfs_err(fs_info, "Missing references.");
5515	ret = -EIO;
5516	goto out_unlock;
5517	}
5518	*lookup_info = 0;
5519
5520	if (wc->stage == DROP_REFERENCE) {
5521	if (wc->refs[level - 1] > 1) {
5522	need_account = true;
5523	if (level == 1 &&
5524	(wc->flags[0] & BTRFS_BLOCK_FLAG_FULL_BACKREF))
5525	goto skip;
5526
5527	if (!wc->update_ref ||
5528	generation <= root->root_key.offset)
5529	goto skip;
5530
5531	btrfs_node_key_to_cpu(eb: path->nodes[level], cpu_key: &key,
5532	nr: path->slots[level]);
5533	ret = btrfs_comp_cpu_keys(k1: &key, k2: &wc->update_progress);
5534	if (ret < 0)
5535	goto skip;
5536
5537	wc->stage = UPDATE_BACKREF;
5538	wc->shared_level = level - 1;
5539	}
5540	} else {
5541	if (level == 1 &&
5542	(wc->flags[0] & BTRFS_BLOCK_FLAG_FULL_BACKREF))
5543	goto skip;
5544	}
5545
5546	if (!btrfs_buffer_uptodate(buf: next, parent_transid: generation, atomic: 0)) {
5547	btrfs_tree_unlock(eb: next);
5548	free_extent_buffer(eb: next);
5549	next = NULL;
5550	*lookup_info = 1;
5551	}
5552
5553	if (!next) {
5554	if (reada && level == 1)
5555	reada_walk_down(trans, root, wc, path);
5556	next = read_tree_block(fs_info, bytenr, check: &check);
5557	if (IS_ERR(ptr: next)) {
5558	return PTR_ERR(ptr: next);
5559	} else if (!extent_buffer_uptodate(eb: next)) {
5560	free_extent_buffer(eb: next);
5561	return -EIO;
5562	}
5563	btrfs_tree_lock(eb: next);
5564	}
5565
5566	level--;
5567	ASSERT(level == btrfs_header_level(next));
5568	if (level != btrfs_header_level(eb: next)) {
5569	btrfs_err(root->fs_info, "mismatched level");
5570	ret = -EIO;
5571	goto out_unlock;
5572	}
5573	path->nodes[level] = next;
5574	path->slots[level] = 0;
5575	path->locks[level] = BTRFS_WRITE_LOCK;
5576	wc->level = level;
5577	if (wc->level == 1)
5578	wc->reada_slot = 0;
5579	return 0;
5580	skip:
5581	wc->refs[level - 1] = 0;
5582	wc->flags[level - 1] = 0;
5583	if (wc->stage == DROP_REFERENCE) {
5584	if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
5585	parent = path->nodes[level]->start;
5586	} else {
5587	ASSERT(root->root_key.objectid ==
5588	btrfs_header_owner(path->nodes[level]));
5589	if (root->root_key.objectid !=
5590	btrfs_header_owner(eb: path->nodes[level])) {
5591	btrfs_err(root->fs_info,
5592	"mismatched block owner");
5593	ret = -EIO;
5594	goto out_unlock;
5595	}
5596	parent = 0;
5597	}
5598
5599	/*
5600	* If we had a drop_progress we need to verify the refs are set
5601	* as expected. If we find our ref then we know that from here
5602	* on out everything should be correct, and we can clear the
5603	* ->restarted flag.
5604	*/
5605	if (wc->restarted) {
5606	ret = check_ref_exists(trans, root, bytenr, parent,
5607	level: level - 1);
5608	if (ret < 0)
5609	goto out_unlock;
5610	if (ret == 0)
5611	goto no_delete;
5612	ret = 0;
5613	wc->restarted = 0;
5614	}
5615
5616	/*
5617	* Reloc tree doesn't contribute to qgroup numbers, and we have
5618	* already accounted them at merge time (replace_path),
5619	* thus we could skip expensive subtree trace here.
5620	*/
5621	if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
5622	need_account) {
5623	ret = btrfs_qgroup_trace_subtree(trans, root_eb: next,
5624	root_gen: generation, root_level: level - 1);
5625	if (ret) {
5626	btrfs_err_rl(fs_info,
5627	"Error %d accounting shared subtree. Quota is out of sync, rescan required.",
5628	ret);
5629	}
5630	}
5631
5632	/*
5633	* We need to update the next key in our walk control so we can
5634	* update the drop_progress key accordingly. We don't care if
5635	* find_next_key doesn't find a key because that means we're at
5636	* the end and are going to clean up now.
5637	*/
5638	wc->drop_level = level;
5639	find_next_key(path, level, key: &wc->drop_progress);
5640
5641	btrfs_init_generic_ref(generic_ref: &ref, action: BTRFS_DROP_DELAYED_REF, bytenr,
5642	len: fs_info->nodesize, parent, owning_root: owner_root);
5643	btrfs_init_tree_ref(generic_ref: &ref, level: level - 1, root: root->root_key.objectid,
5644	mod_root: 0, skip_qgroup: false);
5645	ret = btrfs_free_extent(trans, ref: &ref);
5646	if (ret)
5647	goto out_unlock;
5648	}
5649	no_delete:
5650	*lookup_info = 1;
5651	ret = 1;
5652
5653	out_unlock:
5654	btrfs_tree_unlock(eb: next);
5655	free_extent_buffer(eb: next);
5656
5657	return ret;
5658	}
5659
5660	/*
5661	* helper to process tree block while walking up the tree.
5662	*
5663	* when wc->stage == DROP_REFERENCE, this function drops
5664	* reference count on the block.
5665	*
5666	* when wc->stage == UPDATE_BACKREF, this function changes
5667	* wc->stage back to DROP_REFERENCE if we changed wc->stage
5668	* to UPDATE_BACKREF previously while processing the block.
5669	*
5670	* NOTE: return value 1 means we should stop walking up.
5671	*/
5672	static noinline int walk_up_proc(struct btrfs_trans_handle *trans,
5673	struct btrfs_root *root,
5674	struct btrfs_path *path,
5675	struct walk_control *wc)
5676	{
5677	struct btrfs_fs_info *fs_info = root->fs_info;
5678	int ret;
5679	int level = wc->level;
5680	struct extent_buffer *eb = path->nodes[level];
5681	u64 parent = 0;
5682
5683	if (wc->stage == UPDATE_BACKREF) {
5684	BUG_ON(wc->shared_level < level);
5685	if (level < wc->shared_level)
5686	goto out;
5687
5688	ret = find_next_key(path, level: level + 1, key: &wc->update_progress);
5689	if (ret > 0)
5690	wc->update_ref = 0;
5691
5692	wc->stage = DROP_REFERENCE;
5693	wc->shared_level = -1;
5694	path->slots[level] = 0;
5695
5696	/*
5697	* check reference count again if the block isn't locked.
5698	* we should start walking down the tree again if reference
5699	* count is one.
5700	*/
5701	if (!path->locks[level]) {
5702	BUG_ON(level == 0);
5703	btrfs_tree_lock(eb);
5704	path->locks[level] = BTRFS_WRITE_LOCK;
5705
5706	ret = btrfs_lookup_extent_info(trans, fs_info,
5707	bytenr: eb->start, offset: level, metadata: 1,
5708	refs: &wc->refs[level],
5709	flags: &wc->flags[level],
5710	NULL);
5711	if (ret < 0) {
5712	btrfs_tree_unlock_rw(eb, rw: path->locks[level]);
5713	path->locks[level] = 0;
5714	return ret;
5715	}
5716	BUG_ON(wc->refs[level] == 0);
5717	if (wc->refs[level] == 1) {
5718	btrfs_tree_unlock_rw(eb, rw: path->locks[level]);
5719	path->locks[level] = 0;
5720	return 1;
5721	}
5722	}
5723	}
5724
5725	/* wc->stage == DROP_REFERENCE */
5726	BUG_ON(wc->refs[level] > 1 && !path->locks[level]);
5727
5728	if (wc->refs[level] == 1) {
5729	if (level == 0) {
5730	if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF)
5731	ret = btrfs_dec_ref(trans, root, buf: eb, full_backref: 1);
5732	else
5733	ret = btrfs_dec_ref(trans, root, buf: eb, full_backref: 0);
5734	BUG_ON(ret); /* -ENOMEM */
5735	if (is_fstree(rootid: root->root_key.objectid)) {
5736	ret = btrfs_qgroup_trace_leaf_items(trans, eb);
5737	if (ret) {
5738	btrfs_err_rl(fs_info,
5739	"error %d accounting leaf items, quota is out of sync, rescan required",
5740	ret);
5741	}
5742	}
5743	}
5744	/* Make block locked assertion in btrfs_clear_buffer_dirty happy. */
5745	if (!path->locks[level]) {
5746	btrfs_tree_lock(eb);
5747	path->locks[level] = BTRFS_WRITE_LOCK;
5748	}
5749	btrfs_clear_buffer_dirty(trans, buf: eb);
5750	}
5751
5752	if (eb == root->node) {
5753	if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF)
5754	parent = eb->start;
5755	else if (root->root_key.objectid != btrfs_header_owner(eb))
5756	goto owner_mismatch;
5757	} else {
5758	if (wc->flags[level + 1] & BTRFS_BLOCK_FLAG_FULL_BACKREF)
5759	parent = path->nodes[level + 1]->start;
5760	else if (root->root_key.objectid !=
5761	btrfs_header_owner(eb: path->nodes[level + 1]))
5762	goto owner_mismatch;
5763	}
5764
5765	btrfs_free_tree_block(trans, root_id: btrfs_root_id(root), buf: eb, parent,
5766	last_ref: wc->refs[level] == 1);
5767	out:
5768	wc->refs[level] = 0;
5769	wc->flags[level] = 0;
5770	return 0;
5771
5772	owner_mismatch:
5773	btrfs_err_rl(fs_info, "unexpected tree owner, have %llu expect %llu",
5774	btrfs_header_owner(eb), root->root_key.objectid);
5775	return -EUCLEAN;
5776	}
5777
5778	static noinline int walk_down_tree(struct btrfs_trans_handle *trans,
5779	struct btrfs_root *root,
5780	struct btrfs_path *path,
5781	struct walk_control *wc)
5782	{
5783	int level = wc->level;
5784	int lookup_info = 1;
5785	int ret = 0;
5786
5787	while (level >= 0) {
5788	ret = walk_down_proc(trans, root, path, wc, lookup_info);
5789	if (ret)
5790	break;
5791
5792	if (level == 0)
5793	break;
5794
5795	if (path->slots[level] >=
5796	btrfs_header_nritems(eb: path->nodes[level]))
5797	break;
5798
5799	ret = do_walk_down(trans, root, path, wc, lookup_info: &lookup_info);
5800	if (ret > 0) {
5801	path->slots[level]++;
5802	continue;
5803	} else if (ret < 0)
5804	break;
5805	level = wc->level;
5806	}
5807	return (ret == 1) ? 0 : ret;
5808	}
5809
5810	static noinline int walk_up_tree(struct btrfs_trans_handle *trans,
5811	struct btrfs_root *root,
5812	struct btrfs_path *path,
5813	struct walk_control *wc, int max_level)
5814	{
5815	int level = wc->level;
5816	int ret;
5817
5818	path->slots[level] = btrfs_header_nritems(eb: path->nodes[level]);
5819	while (level < max_level && path->nodes[level]) {
5820	wc->level = level;
5821	if (path->slots[level] + 1 <
5822	btrfs_header_nritems(eb: path->nodes[level])) {
5823	path->slots[level]++;
5824	return 0;
5825	} else {
5826	ret = walk_up_proc(trans, root, path, wc);
5827	if (ret > 0)
5828	return 0;
5829	if (ret < 0)
5830	return ret;
5831
5832	if (path->locks[level]) {
5833	btrfs_tree_unlock_rw(eb: path->nodes[level],
5834	rw: path->locks[level]);
5835	path->locks[level] = 0;
5836	}
5837	free_extent_buffer(eb: path->nodes[level]);
5838	path->nodes[level] = NULL;
5839	level++;
5840	}
5841	}
5842	return 1;
5843	}
5844
5845	/*
5846	* drop a subvolume tree.
5847	*
5848	* this function traverses the tree freeing any blocks that only
5849	* referenced by the tree.
5850	*
5851	* when a shared tree block is found. this function decreases its
5852	* reference count by one. if update_ref is true, this function
5853	* also make sure backrefs for the shared block and all lower level
5854	* blocks are properly updated.
5855	*
5856	* If called with for_reloc == 0, may exit early with -EAGAIN
5857	*/
5858	int btrfs_drop_snapshot(struct btrfs_root *root, int update_ref, int for_reloc)
5859	{
5860	const bool is_reloc_root = (root->root_key.objectid ==
5861	BTRFS_TREE_RELOC_OBJECTID);
5862	struct btrfs_fs_info *fs_info = root->fs_info;
5863	struct btrfs_path *path;
5864	struct btrfs_trans_handle *trans;
5865	struct btrfs_root *tree_root = fs_info->tree_root;
5866	struct btrfs_root_item *root_item = &root->root_item;
5867	struct walk_control *wc;
5868	struct btrfs_key key;
5869	int err = 0;
5870	int ret;
5871	int level;
5872	bool root_dropped = false;
5873	bool unfinished_drop = false;
5874
5875	btrfs_debug(fs_info, "Drop subvolume %llu", root->root_key.objectid);
5876
5877	path = btrfs_alloc_path();
5878	if (!path) {
5879	err = -ENOMEM;
5880	goto out;
5881	}
5882
5883	wc = kzalloc(size: sizeof(*wc), GFP_NOFS);
5884	if (!wc) {
5885	btrfs_free_path(p: path);
5886	err = -ENOMEM;
5887	goto out;
5888	}
5889
5890	/*
5891	* Use join to avoid potential EINTR from transaction start. See
5892	* wait_reserve_ticket and the whole reservation callchain.
5893	*/
5894	if (for_reloc)
5895	trans = btrfs_join_transaction(root: tree_root);
5896	else
5897	trans = btrfs_start_transaction(root: tree_root, num_items: 0);
5898	if (IS_ERR(ptr: trans)) {
5899	err = PTR_ERR(ptr: trans);
5900	goto out_free;
5901	}
5902
5903	err = btrfs_run_delayed_items(trans);
5904	if (err)
5905	goto out_end_trans;
5906
5907	/*
5908	* This will help us catch people modifying the fs tree while we're
5909	* dropping it. It is unsafe to mess with the fs tree while it's being
5910	* dropped as we unlock the root node and parent nodes as we walk down
5911	* the tree, assuming nothing will change. If something does change
5912	* then we'll have stale information and drop references to blocks we've
5913	* already dropped.
5914	*/
5915	set_bit(nr: BTRFS_ROOT_DELETING, addr: &root->state);
5916	unfinished_drop = test_bit(BTRFS_ROOT_UNFINISHED_DROP, &root->state);
5917
5918	if (btrfs_disk_key_objectid(s: &root_item->drop_progress) == 0) {
5919	level = btrfs_header_level(eb: root->node);
5920	path->nodes[level] = btrfs_lock_root_node(root);
5921	path->slots[level] = 0;
5922	path->locks[level] = BTRFS_WRITE_LOCK;
5923	memset(&wc->update_progress, 0,
5924	sizeof(wc->update_progress));
5925	} else {
5926	btrfs_disk_key_to_cpu(cpu_key: &key, disk_key: &root_item->drop_progress);
5927	memcpy(&wc->update_progress, &key,
5928	sizeof(wc->update_progress));
5929
5930	level = btrfs_root_drop_level(s: root_item);
5931	BUG_ON(level == 0);
5932	path->lowest_level = level;
5933	ret = btrfs_search_slot(NULL, root, key: &key, p: path, ins_len: 0, cow: 0);
5934	path->lowest_level = 0;
5935	if (ret < 0) {
5936	err = ret;
5937	goto out_end_trans;
5938	}
5939	WARN_ON(ret > 0);
5940
5941	/*
5942	* unlock our path, this is safe because only this
5943	* function is allowed to delete this snapshot
5944	*/
5945	btrfs_unlock_up_safe(path, level: 0);
5946
5947	level = btrfs_header_level(eb: root->node);
5948	while (1) {
5949	btrfs_tree_lock(eb: path->nodes[level]);
5950	path->locks[level] = BTRFS_WRITE_LOCK;
5951
5952	ret = btrfs_lookup_extent_info(trans, fs_info,
5953	bytenr: path->nodes[level]->start,
5954	offset: level, metadata: 1, refs: &wc->refs[level],
5955	flags: &wc->flags[level], NULL);
5956	if (ret < 0) {
5957	err = ret;
5958	goto out_end_trans;
5959	}
5960	BUG_ON(wc->refs[level] == 0);
5961
5962	if (level == btrfs_root_drop_level(s: root_item))
5963	break;
5964
5965	btrfs_tree_unlock(eb: path->nodes[level]);
5966	path->locks[level] = 0;
5967	WARN_ON(wc->refs[level] != 1);
5968	level--;
5969	}
5970	}
5971
5972	wc->restarted = test_bit(BTRFS_ROOT_DEAD_TREE, &root->state);
5973	wc->level = level;
5974	wc->shared_level = -1;
5975	wc->stage = DROP_REFERENCE;
5976	wc->update_ref = update_ref;
5977	wc->keep_locks = 0;
5978	wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(info: fs_info);
5979
5980	while (1) {
5981
5982	ret = walk_down_tree(trans, root, path, wc);
5983	if (ret < 0) {
5984	btrfs_abort_transaction(trans, ret);
5985	err = ret;
5986	break;
5987	}
5988
5989	ret = walk_up_tree(trans, root, path, wc, BTRFS_MAX_LEVEL);
5990	if (ret < 0) {
5991	btrfs_abort_transaction(trans, ret);
5992	err = ret;
5993	break;
5994	}
5995
5996	if (ret > 0) {
5997	BUG_ON(wc->stage != DROP_REFERENCE);
5998	break;
5999	}
6000
6001	if (wc->stage == DROP_REFERENCE) {
6002	wc->drop_level = wc->level;
6003	btrfs_node_key_to_cpu(eb: path->nodes[wc->drop_level],
6004	cpu_key: &wc->drop_progress,
6005	nr: path->slots[wc->drop_level]);
6006	}
6007	btrfs_cpu_key_to_disk(disk_key: &root_item->drop_progress,
6008	cpu_key: &wc->drop_progress);
6009	btrfs_set_root_drop_level(s: root_item, val: wc->drop_level);
6010
6011	BUG_ON(wc->level == 0);
6012	if (btrfs_should_end_transaction(trans) ||
6013	(!for_reloc && btrfs_need_cleaner_sleep(fs_info))) {
6014	ret = btrfs_update_root(trans, root: tree_root,
6015	key: &root->root_key,
6016	item: root_item);
6017	if (ret) {
6018	btrfs_abort_transaction(trans, ret);
6019	err = ret;
6020	goto out_end_trans;
6021	}
6022
6023	if (!is_reloc_root)
6024	btrfs_set_last_root_drop_gen(fs_info, gen: trans->transid);
6025
6026	btrfs_end_transaction_throttle(trans);
6027	if (!for_reloc && btrfs_need_cleaner_sleep(fs_info)) {
6028	btrfs_debug(fs_info,
6029	"drop snapshot early exit");
6030	err = -EAGAIN;
6031	goto out_free;
6032	}
6033
6034	/*
6035	* Use join to avoid potential EINTR from transaction
6036	* start. See wait_reserve_ticket and the whole
6037	* reservation callchain.
6038	*/
6039	if (for_reloc)
6040	trans = btrfs_join_transaction(root: tree_root);
6041	else
6042	trans = btrfs_start_transaction(root: tree_root, num_items: 0);
6043	if (IS_ERR(ptr: trans)) {
6044	err = PTR_ERR(ptr: trans);
6045	goto out_free;
6046	}
6047	}
6048	}
6049	btrfs_release_path(p: path);
6050	if (err)
6051	goto out_end_trans;
6052
6053	ret = btrfs_del_root(trans, key: &root->root_key);
6054	if (ret) {
6055	btrfs_abort_transaction(trans, ret);
6056	err = ret;
6057	goto out_end_trans;
6058	}
6059
6060	if (!is_reloc_root) {
6061	ret = btrfs_find_root(root: tree_root, search_key: &root->root_key, path,
6062	NULL, NULL);
6063	if (ret < 0) {
6064	btrfs_abort_transaction(trans, ret);
6065	err = ret;
6066	goto out_end_trans;
6067	} else if (ret > 0) {
6068	/* if we fail to delete the orphan item this time
6069	* around, it'll get picked up the next time.
6070	*
6071	* The most common failure here is just -ENOENT.
6072	*/
6073	btrfs_del_orphan_item(trans, root: tree_root,
6074	offset: root->root_key.objectid);
6075	}
6076	}
6077
6078	/*
6079	* This subvolume is going to be completely dropped, and won't be
6080	* recorded as dirty roots, thus pertrans meta rsv will not be freed at
6081	* commit transaction time. So free it here manually.
6082	*/
6083	btrfs_qgroup_convert_reserved_meta(root, INT_MAX);
6084	btrfs_qgroup_free_meta_all_pertrans(root);
6085
6086	if (test_bit(BTRFS_ROOT_IN_RADIX, &root->state))
6087	btrfs_add_dropped_root(trans, root);
6088	else
6089	btrfs_put_root(root);
6090	root_dropped = true;
6091	out_end_trans:
6092	if (!is_reloc_root)
6093	btrfs_set_last_root_drop_gen(fs_info, gen: trans->transid);
6094
6095	btrfs_end_transaction_throttle(trans);
6096	out_free:
6097	kfree(objp: wc);
6098	btrfs_free_path(p: path);
6099	out:
6100	/*
6101	* We were an unfinished drop root, check to see if there are any
6102	* pending, and if not clear and wake up any waiters.
6103	*/
6104	if (!err && unfinished_drop)
6105	btrfs_maybe_wake_unfinished_drop(fs_info);
6106
6107	/*
6108	* So if we need to stop dropping the snapshot for whatever reason we
6109	* need to make sure to add it back to the dead root list so that we
6110	* keep trying to do the work later. This also cleans up roots if we
6111	* don't have it in the radix (like when we recover after a power fail
6112	* or unmount) so we don't leak memory.
6113	*/
6114	if (!for_reloc && !root_dropped)
6115	btrfs_add_dead_root(root);
6116	return err;
6117	}
6118
6119	/*
6120	* drop subtree rooted at tree block 'node'.
6121	*
6122	* NOTE: this function will unlock and release tree block 'node'
6123	* only used by relocation code
6124	*/
6125	int btrfs_drop_subtree(struct btrfs_trans_handle *trans,
6126	struct btrfs_root *root,
6127	struct extent_buffer *node,
6128	struct extent_buffer *parent)
6129	{
6130	struct btrfs_fs_info *fs_info = root->fs_info;
6131	struct btrfs_path *path;
6132	struct walk_control *wc;
6133	int level;
6134	int parent_level;
6135	int ret = 0;
6136	int wret;
6137
6138	BUG_ON(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
6139
6140	path = btrfs_alloc_path();
6141	if (!path)
6142	return -ENOMEM;
6143
6144	wc = kzalloc(size: sizeof(*wc), GFP_NOFS);
6145	if (!wc) {
6146	btrfs_free_path(p: path);
6147	return -ENOMEM;
6148	}
6149
6150	btrfs_assert_tree_write_locked(eb: parent);
6151	parent_level = btrfs_header_level(eb: parent);
6152	atomic_inc(v: &parent->refs);
6153	path->nodes[parent_level] = parent;
6154	path->slots[parent_level] = btrfs_header_nritems(eb: parent);
6155
6156	btrfs_assert_tree_write_locked(eb: node);
6157	level = btrfs_header_level(eb: node);
6158	path->nodes[level] = node;
6159	path->slots[level] = 0;
6160	path->locks[level] = BTRFS_WRITE_LOCK;
6161
6162	wc->refs[parent_level] = 1;
6163	wc->flags[parent_level] = BTRFS_BLOCK_FLAG_FULL_BACKREF;
6164	wc->level = level;
6165	wc->shared_level = -1;
6166	wc->stage = DROP_REFERENCE;
6167	wc->update_ref = 0;
6168	wc->keep_locks = 1;
6169	wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(info: fs_info);
6170
6171	while (1) {
6172	wret = walk_down_tree(trans, root, path, wc);
6173	if (wret < 0) {
6174	ret = wret;
6175	break;
6176	}
6177
6178	wret = walk_up_tree(trans, root, path, wc, max_level: parent_level);
6179	if (wret < 0)
6180	ret = wret;
6181	if (wret != 0)
6182	break;
6183	}
6184
6185	kfree(objp: wc);
6186	btrfs_free_path(p: path);
6187	return ret;
6188	}
6189
6190	/*
6191	* Unpin the extent range in an error context and don't add the space back.
6192	* Errors are not propagated further.
6193	*/
6194	void btrfs_error_unpin_extent_range(struct btrfs_fs_info *fs_info, u64 start, u64 end)
6195	{
6196	unpin_extent_range(fs_info, start, end, return_free_space: false);
6197	}
6198
6199	/*
6200	* It used to be that old block groups would be left around forever.
6201	* Iterating over them would be enough to trim unused space. Since we
6202	* now automatically remove them, we also need to iterate over unallocated
6203	* space.
6204	*
6205	* We don't want a transaction for this since the discard may take a
6206	* substantial amount of time. We don't require that a transaction be
6207	* running, but we do need to take a running transaction into account
6208	* to ensure that we're not discarding chunks that were released or
6209	* allocated in the current transaction.
6210	*
6211	* Holding the chunks lock will prevent other threads from allocating
6212	* or releasing chunks, but it won't prevent a running transaction
6213	* from committing and releasing the memory that the pending chunks
6214	* list head uses. For that, we need to take a reference to the
6215	* transaction and hold the commit root sem. We only need to hold
6216	* it while performing the free space search since we have already
6217	* held back allocations.
6218	*/
6219	static int btrfs_trim_free_extents(struct btrfs_device *device, u64 *trimmed)
6220	{
6221	u64 start = BTRFS_DEVICE_RANGE_RESERVED, len = 0, end = 0;
6222	int ret;
6223
6224	*trimmed = 0;
6225
6226	/* Discard not supported = nothing to do. */
6227	if (!bdev_max_discard_sectors(bdev: device->bdev))
6228	return 0;
6229
6230	/* Not writable = nothing to do. */
6231	if (!test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state))
6232	return 0;
6233
6234	/* No free space = nothing to do. */
6235	if (device->total_bytes <= device->bytes_used)
6236	return 0;
6237
6238	ret = 0;
6239
6240	while (1) {
6241	struct btrfs_fs_info *fs_info = device->fs_info;
6242	u64 bytes;
6243
6244	ret = mutex_lock_interruptible(&fs_info->chunk_mutex);
6245	if (ret)
6246	break;
6247
6248	find_first_clear_extent_bit(tree: &device->alloc_state, start,
6249	start_ret: &start, end_ret: &end,
6250	CHUNK_TRIMMED | CHUNK_ALLOCATED);
6251
6252	/* Check if there are any CHUNK_* bits left */
6253	if (start > device->total_bytes) {
6254	WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
6255	btrfs_warn_in_rcu(fs_info,
6256	"ignoring attempt to trim beyond device size: offset %llu length %llu device %s device size %llu",
6257	start, end - start + 1,
6258	btrfs_dev_name(device),
6259	device->total_bytes);
6260	mutex_unlock(lock: &fs_info->chunk_mutex);
6261	ret = 0;
6262	break;
6263	}
6264
6265	/* Ensure we skip the reserved space on each device. */
6266	start = max_t(u64, start, BTRFS_DEVICE_RANGE_RESERVED);
6267
6268	/*
6269	* If find_first_clear_extent_bit find a range that spans the
6270	* end of the device it will set end to -1, in this case it's up
6271	* to the caller to trim the value to the size of the device.
6272	*/
6273	end = min(end, device->total_bytes - 1);
6274
6275	len = end - start + 1;
6276
6277	/* We didn't find any extents */
6278	if (!len) {
6279	mutex_unlock(lock: &fs_info->chunk_mutex);
6280	ret = 0;
6281	break;
6282	}
6283
6284	ret = btrfs_issue_discard(bdev: device->bdev, start, len,
6285	discarded_bytes: &bytes);
6286	if (!ret)
6287	set_extent_bit(tree: &device->alloc_state, start,
6288	end: start + bytes - 1, CHUNK_TRIMMED, NULL);
6289	mutex_unlock(lock: &fs_info->chunk_mutex);
6290
6291	if (ret)
6292	break;
6293
6294	start += len;
6295	*trimmed += bytes;
6296
6297	if (fatal_signal_pending(current)) {
6298	ret = -ERESTARTSYS;
6299	break;
6300	}
6301
6302	cond_resched();
6303	}
6304
6305	return ret;
6306	}
6307
6308	/*
6309	* Trim the whole filesystem by:
6310	* 1) trimming the free space in each block group
6311	* 2) trimming the unallocated space on each device
6312	*
6313	* This will also continue trimming even if a block group or device encounters
6314	* an error. The return value will be the last error, or 0 if nothing bad
6315	* happens.
6316	*/
6317	int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
6318	{
6319	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
6320	struct btrfs_block_group *cache = NULL;
6321	struct btrfs_device *device;
6322	u64 group_trimmed;
6323	u64 range_end = U64_MAX;
6324	u64 start;
6325	u64 end;
6326	u64 trimmed = 0;
6327	u64 bg_failed = 0;
6328	u64 dev_failed = 0;
6329	int bg_ret = 0;
6330	int dev_ret = 0;
6331	int ret = 0;
6332
6333	if (range->start == U64_MAX)
6334	return -EINVAL;
6335
6336	/*
6337	* Check range overflow if range->len is set.
6338	* The default range->len is U64_MAX.
6339	*/
6340	if (range->len != U64_MAX &&
6341	check_add_overflow(range->start, range->len, &range_end))
6342	return -EINVAL;
6343
6344	cache = btrfs_lookup_first_block_group(info: fs_info, bytenr: range->start);
6345	for (; cache; cache = btrfs_next_block_group(cache)) {
6346	if (cache->start >= range_end) {
6347	btrfs_put_block_group(cache);
6348	break;
6349	}
6350
6351	start = max(range->start, cache->start);
6352	end = min(range_end, cache->start + cache->length);
6353
6354	if (end - start >= range->minlen) {
6355	if (!btrfs_block_group_done(cache)) {
6356	ret = btrfs_cache_block_group(cache, wait: true);
6357	if (ret) {
6358	bg_failed++;
6359	bg_ret = ret;
6360	continue;
6361	}
6362	}
6363	ret = btrfs_trim_block_group(block_group: cache,
6364	trimmed: &group_trimmed,
6365	start,
6366	end,
6367	minlen: range->minlen);
6368
6369	trimmed += group_trimmed;
6370	if (ret) {
6371	bg_failed++;
6372	bg_ret = ret;
6373	continue;
6374	}
6375	}
6376	}
6377
6378	if (bg_failed)
6379	btrfs_warn(fs_info,
6380	"failed to trim %llu block group(s), last error %d",
6381	bg_failed, bg_ret);
6382
6383	mutex_lock(&fs_devices->device_list_mutex);
6384	list_for_each_entry(device, &fs_devices->devices, dev_list) {
6385	if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))
6386	continue;
6387
6388	ret = btrfs_trim_free_extents(device, trimmed: &group_trimmed);
6389	if (ret) {
6390	dev_failed++;
6391	dev_ret = ret;
6392	break;
6393	}
6394
6395	trimmed += group_trimmed;
6396	}
6397	mutex_unlock(lock: &fs_devices->device_list_mutex);
6398
6399	if (dev_failed)
6400	btrfs_warn(fs_info,
6401	"failed to trim %llu device(s), last error %d",
6402	dev_failed, dev_ret);
6403	range->len = trimmed;
6404	if (bg_ret)
6405	return bg_ret;
6406	return dev_ret;
6407	}
6408