1	// SPDX-License-Identifier: GPL-2.0
2	/*
3	* Copyright (c) 2000-2006 Silicon Graphics, Inc.
4	* All Rights Reserved.
5	*/
6	#include "xfs.h"
7	#include <linux/backing-dev.h>
8	#include <linux/dax.h>
9
10	#include "xfs_shared.h"
11	#include "xfs_format.h"
12	#include "xfs_log_format.h"
13	#include "xfs_trans_resv.h"
14	#include "xfs_mount.h"
15	#include "xfs_trace.h"
16	#include "xfs_log.h"
17	#include "xfs_log_recover.h"
18	#include "xfs_log_priv.h"
19	#include "xfs_trans.h"
20	#include "xfs_buf_item.h"
21	#include "xfs_errortag.h"
22	#include "xfs_error.h"
23	#include "xfs_ag.h"
24	#include "xfs_buf_mem.h"
25
26	struct kmem_cache *xfs_buf_cache;
27
28	/*
29	* Locking orders
30	*
31	* xfs_buf_ioacct_inc:
32	* xfs_buf_ioacct_dec:
33	* b_sema (caller holds)
34	* b_lock
35	*
36	* xfs_buf_stale:
37	* b_sema (caller holds)
38	* b_lock
39	* lru_lock
40	*
41	* xfs_buf_rele:
42	* b_lock
43	* pag_buf_lock
44	* lru_lock
45	*
46	* xfs_buftarg_drain_rele
47	* lru_lock
48	* b_lock (trylock due to inversion)
49	*
50	* xfs_buftarg_isolate
51	* lru_lock
52	* b_lock (trylock due to inversion)
53	*/
54
55	static int __xfs_buf_submit(struct xfs_buf *bp, bool wait);
56
57	static inline int
58	xfs_buf_submit(
59	struct xfs_buf *bp)
60	{
61	return __xfs_buf_submit(bp, wait: !(bp->b_flags & XBF_ASYNC));
62	}
63
64	static inline bool xfs_buf_is_uncached(struct xfs_buf *bp)
65	{
66	return bp->b_rhash_key == XFS_BUF_DADDR_NULL;
67	}
68
69	static inline int
70	xfs_buf_is_vmapped(
71	struct xfs_buf *bp)
72	{
73	/*
74	* Return true if the buffer is vmapped.
75	*
76	* b_addr is null if the buffer is not mapped, but the code is clever
77	* enough to know it doesn't have to map a single page, so the check has
78	* to be both for b_addr and bp->b_page_count > 1.
79	*/
80	return bp->b_addr && bp->b_page_count > 1;
81	}
82
83	static inline int
84	xfs_buf_vmap_len(
85	struct xfs_buf *bp)
86	{
87	return (bp->b_page_count * PAGE_SIZE);
88	}
89
90	/*
91	* Bump the I/O in flight count on the buftarg if we haven't yet done so for
92	* this buffer. The count is incremented once per buffer (per hold cycle)
93	* because the corresponding decrement is deferred to buffer release. Buffers
94	* can undergo I/O multiple times in a hold-release cycle and per buffer I/O
95	* tracking adds unnecessary overhead. This is used for sychronization purposes
96	* with unmount (see xfs_buftarg_drain()), so all we really need is a count of
97	* in-flight buffers.
98	*
99	* Buffers that are never released (e.g., superblock, iclog buffers) must set
100	* the XBF_NO_IOACCT flag before I/O submission. Otherwise, the buftarg count
101	* never reaches zero and unmount hangs indefinitely.
102	*/
103	static inline void
104	xfs_buf_ioacct_inc(
105	struct xfs_buf *bp)
106	{
107	if (bp->b_flags & XBF_NO_IOACCT)
108	return;
109
110	ASSERT(bp->b_flags & XBF_ASYNC);
111	spin_lock(lock: &bp->b_lock);
112	if (!(bp->b_state & XFS_BSTATE_IN_FLIGHT)) {
113	bp->b_state |= XFS_BSTATE_IN_FLIGHT;
114	percpu_counter_inc(fbc: &bp->b_target->bt_io_count);
115	}
116	spin_unlock(lock: &bp->b_lock);
117	}
118
119	/*
120	* Clear the in-flight state on a buffer about to be released to the LRU or
121	* freed and unaccount from the buftarg.
122	*/
123	static inline void
124	__xfs_buf_ioacct_dec(
125	struct xfs_buf *bp)
126	{
127	lockdep_assert_held(&bp->b_lock);
128
129	if (bp->b_state & XFS_BSTATE_IN_FLIGHT) {
130	bp->b_state &= ~XFS_BSTATE_IN_FLIGHT;
131	percpu_counter_dec(fbc: &bp->b_target->bt_io_count);
132	}
133	}
134
135	static inline void
136	xfs_buf_ioacct_dec(
137	struct xfs_buf *bp)
138	{
139	spin_lock(lock: &bp->b_lock);
140	__xfs_buf_ioacct_dec(bp);
141	spin_unlock(lock: &bp->b_lock);
142	}
143
144	/*
145	* When we mark a buffer stale, we remove the buffer from the LRU and clear the
146	* b_lru_ref count so that the buffer is freed immediately when the buffer
147	* reference count falls to zero. If the buffer is already on the LRU, we need
148	* to remove the reference that LRU holds on the buffer.
149	*
150	* This prevents build-up of stale buffers on the LRU.
151	*/
152	void
153	xfs_buf_stale(
154	struct xfs_buf *bp)
155	{
156	ASSERT(xfs_buf_islocked(bp));
157
158	bp->b_flags |= XBF_STALE;
159
160	/*
161	* Clear the delwri status so that a delwri queue walker will not
162	* flush this buffer to disk now that it is stale. The delwri queue has
163	* a reference to the buffer, so this is safe to do.
164	*/
165	bp->b_flags &= ~_XBF_DELWRI_Q;
166
167	/*
168	* Once the buffer is marked stale and unlocked, a subsequent lookup
169	* could reset b_flags. There is no guarantee that the buffer is
170	* unaccounted (released to LRU) before that occurs. Drop in-flight
171	* status now to preserve accounting consistency.
172	*/
173	spin_lock(lock: &bp->b_lock);
174	__xfs_buf_ioacct_dec(bp);
175
176	atomic_set(v: &bp->b_lru_ref, i: 0);
177	if (!(bp->b_state & XFS_BSTATE_DISPOSE) &&
178	(list_lru_del_obj(lru: &bp->b_target->bt_lru, item: &bp->b_lru)))
179	atomic_dec(v: &bp->b_hold);
180
181	ASSERT(atomic_read(&bp->b_hold) >= 1);
182	spin_unlock(lock: &bp->b_lock);
183	}
184
185	static int
186	xfs_buf_get_maps(
187	struct xfs_buf *bp,
188	int map_count)
189	{
190	ASSERT(bp->b_maps == NULL);
191	bp->b_map_count = map_count;
192
193	if (map_count == 1) {
194	bp->b_maps = &bp->__b_map;
195	return 0;
196	}
197
198	bp->b_maps = kzalloc(size: map_count * sizeof(struct xfs_buf_map),
199	GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
200	if (!bp->b_maps)
201	return -ENOMEM;
202	return 0;
203	}
204
205	/*
206	* Frees b_pages if it was allocated.
207	*/
208	static void
209	xfs_buf_free_maps(
210	struct xfs_buf *bp)
211	{
212	if (bp->b_maps != &bp->__b_map) {
213	kfree(objp: bp->b_maps);
214	bp->b_maps = NULL;
215	}
216	}
217
218	static int
219	_xfs_buf_alloc(
220	struct xfs_buftarg *target,
221	struct xfs_buf_map *map,
222	int nmaps,
223	xfs_buf_flags_t flags,
224	struct xfs_buf **bpp)
225	{
226	struct xfs_buf *bp;
227	int error;
228	int i;
229
230	*bpp = NULL;
231	bp = kmem_cache_zalloc(k: xfs_buf_cache,
232	GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
233
234	/*
235	* We don't want certain flags to appear in b_flags unless they are
236	* specifically set by later operations on the buffer.
237	*/
238	flags &= ~(XBF_UNMAPPED | XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD);
239
240	atomic_set(v: &bp->b_hold, i: 1);
241	atomic_set(v: &bp->b_lru_ref, i: 1);
242	init_completion(x: &bp->b_iowait);
243	INIT_LIST_HEAD(list: &bp->b_lru);
244	INIT_LIST_HEAD(list: &bp->b_list);
245	INIT_LIST_HEAD(list: &bp->b_li_list);
246	sema_init(sem: &bp->b_sema, val: 0); /* held, no waiters */
247	spin_lock_init(&bp->b_lock);
248	bp->b_target = target;
249	bp->b_mount = target->bt_mount;
250	bp->b_flags = flags;
251
252	/*
253	* Set length and io_length to the same value initially.
254	* I/O routines should use io_length, which will be the same in
255	* most cases but may be reset (e.g. XFS recovery).
256	*/
257	error = xfs_buf_get_maps(bp, map_count: nmaps);
258	if (error) {
259	kmem_cache_free(s: xfs_buf_cache, objp: bp);
260	return error;
261	}
262
263	bp->b_rhash_key = map[0].bm_bn;
264	bp->b_length = 0;
265	for (i = 0; i < nmaps; i++) {
266	bp->b_maps[i].bm_bn = map[i].bm_bn;
267	bp->b_maps[i].bm_len = map[i].bm_len;
268	bp->b_length += map[i].bm_len;
269	}
270
271	atomic_set(v: &bp->b_pin_count, i: 0);
272	init_waitqueue_head(&bp->b_waiters);
273
274	XFS_STATS_INC(bp->b_mount, xb_create);
275	trace_xfs_buf_init(bp, _RET_IP_);
276
277	*bpp = bp;
278	return 0;
279	}
280
281	static void
282	xfs_buf_free_pages(
283	struct xfs_buf *bp)
284	{
285	uint i;
286
287	ASSERT(bp->b_flags & _XBF_PAGES);
288
289	if (xfs_buf_is_vmapped(bp))
290	vm_unmap_ram(mem: bp->b_addr, count: bp->b_page_count);
291
292	for (i = 0; i < bp->b_page_count; i++) {
293	if (bp->b_pages[i])
294	__free_page(bp->b_pages[i]);
295	}
296	mm_account_reclaimed_pages(pages: bp->b_page_count);
297
298	if (bp->b_pages != bp->b_page_array)
299	kfree(objp: bp->b_pages);
300	bp->b_pages = NULL;
301	bp->b_flags &= ~_XBF_PAGES;
302	}
303
304	static void
305	xfs_buf_free_callback(
306	struct callback_head *cb)
307	{
308	struct xfs_buf *bp = container_of(cb, struct xfs_buf, b_rcu);
309
310	xfs_buf_free_maps(bp);
311	kmem_cache_free(s: xfs_buf_cache, objp: bp);
312	}
313
314	static void
315	xfs_buf_free(
316	struct xfs_buf *bp)
317	{
318	trace_xfs_buf_free(bp, _RET_IP_);
319
320	ASSERT(list_empty(&bp->b_lru));
321
322	if (xfs_buftarg_is_mem(btp: bp->b_target))
323	xmbuf_unmap_page(bp);
324	else if (bp->b_flags & _XBF_PAGES)
325	xfs_buf_free_pages(bp);
326	else if (bp->b_flags & _XBF_KMEM)
327	kfree(objp: bp->b_addr);
328
329	call_rcu(head: &bp->b_rcu, func: xfs_buf_free_callback);
330	}
331
332	static int
333	xfs_buf_alloc_kmem(
334	struct xfs_buf *bp,
335	xfs_buf_flags_t flags)
336	{
337	gfp_t gfp_mask = GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL;
338	size_t size = BBTOB(bp->b_length);
339
340	/* Assure zeroed buffer for non-read cases. */
341	if (!(flags & XBF_READ))
342	gfp_mask |= __GFP_ZERO;
343
344	bp->b_addr = kmalloc(size, flags: gfp_mask);
345	if (!bp->b_addr)
346	return -ENOMEM;
347
348	if (((unsigned long)(bp->b_addr + size - 1) & PAGE_MASK) !=
349	((unsigned long)bp->b_addr & PAGE_MASK)) {
350	/* b_addr spans two pages - use alloc_page instead */
351	kfree(objp: bp->b_addr);
352	bp->b_addr = NULL;
353	return -ENOMEM;
354	}
355	bp->b_offset = offset_in_page(bp->b_addr);
356	bp->b_pages = bp->b_page_array;
357	bp->b_pages[0] = kmem_to_page(addr: bp->b_addr);
358	bp->b_page_count = 1;
359	bp->b_flags |= _XBF_KMEM;
360	return 0;
361	}
362
363	static int
364	xfs_buf_alloc_pages(
365	struct xfs_buf *bp,
366	xfs_buf_flags_t flags)
367	{
368	gfp_t gfp_mask = GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOWARN;
369	long filled = 0;
370
371	if (flags & XBF_READ_AHEAD)
372	gfp_mask |= __GFP_NORETRY;
373
374	/* Make sure that we have a page list */
375	bp->b_page_count = DIV_ROUND_UP(BBTOB(bp->b_length), PAGE_SIZE);
376	if (bp->b_page_count <= XB_PAGES) {
377	bp->b_pages = bp->b_page_array;
378	} else {
379	bp->b_pages = kzalloc(size: sizeof(struct page *) * bp->b_page_count,
380	flags: gfp_mask);
381	if (!bp->b_pages)
382	return -ENOMEM;
383	}
384	bp->b_flags |= _XBF_PAGES;
385
386	/* Assure zeroed buffer for non-read cases. */
387	if (!(flags & XBF_READ))
388	gfp_mask |= __GFP_ZERO;
389
390	/*
391	* Bulk filling of pages can take multiple calls. Not filling the entire
392	* array is not an allocation failure, so don't back off if we get at
393	* least one extra page.
394	*/
395	for (;;) {
396	long last = filled;
397
398	filled = alloc_pages_bulk_array(gfp: gfp_mask, nr_pages: bp->b_page_count,
399	page_array: bp->b_pages);
400	if (filled == bp->b_page_count) {
401	XFS_STATS_INC(bp->b_mount, xb_page_found);
402	break;
403	}
404
405	if (filled != last)
406	continue;
407
408	if (flags & XBF_READ_AHEAD) {
409	xfs_buf_free_pages(bp);
410	return -ENOMEM;
411	}
412
413	XFS_STATS_INC(bp->b_mount, xb_page_retries);
414	memalloc_retry_wait(gfp_flags: gfp_mask);
415	}
416	return 0;
417	}
418
419	/*
420	* Map buffer into kernel address-space if necessary.
421	*/
422	STATIC int
423	_xfs_buf_map_pages(
424	struct xfs_buf *bp,
425	xfs_buf_flags_t flags)
426	{
427	ASSERT(bp->b_flags & _XBF_PAGES);
428	if (bp->b_page_count == 1) {
429	/* A single page buffer is always mappable */
430	bp->b_addr = page_address(bp->b_pages[0]);
431	} else if (flags & XBF_UNMAPPED) {
432	bp->b_addr = NULL;
433	} else {
434	int retried = 0;
435	unsigned nofs_flag;
436
437	/*
438	* vm_map_ram() will allocate auxiliary structures (e.g.
439	* pagetables) with GFP_KERNEL, yet we often under a scoped nofs
440	* context here. Mixing GFP_KERNEL with GFP_NOFS allocations
441	* from the same call site that can be run from both above and
442	* below memory reclaim causes lockdep false positives. Hence we
443	* always need to force this allocation to nofs context because
444	* we can't pass __GFP_NOLOCKDEP down to auxillary structures to
445	* prevent false positive lockdep reports.
446	*
447	* XXX(dgc): I think dquot reclaim is the only place we can get
448	* to this function from memory reclaim context now. If we fix
449	* that like we've fixed inode reclaim to avoid writeback from
450	* reclaim, this nofs wrapping can go away.
451	*/
452	nofs_flag = memalloc_nofs_save();
453	do {
454	bp->b_addr = vm_map_ram(pages: bp->b_pages, count: bp->b_page_count,
455	node: -1);
456	if (bp->b_addr)
457	break;
458	vm_unmap_aliases();
459	} while (retried++ <= 1);
460	memalloc_nofs_restore(flags: nofs_flag);
461
462	if (!bp->b_addr)
463	return -ENOMEM;
464	}
465
466	return 0;
467	}
468
469	/*
470	* Finding and Reading Buffers
471	*/
472	static int
473	_xfs_buf_obj_cmp(
474	struct rhashtable_compare_arg *arg,
475	const void *obj)
476	{
477	const struct xfs_buf_map *map = arg->key;
478	const struct xfs_buf *bp = obj;
479
480	/*
481	* The key hashing in the lookup path depends on the key being the
482	* first element of the compare_arg, make sure to assert this.
483	*/
484	BUILD_BUG_ON(offsetof(struct xfs_buf_map, bm_bn) != 0);
485
486	if (bp->b_rhash_key != map->bm_bn)
487	return 1;
488
489	if (unlikely(bp->b_length != map->bm_len)) {
490	/*
491	* found a block number match. If the range doesn't
492	* match, the only way this is allowed is if the buffer
493	* in the cache is stale and the transaction that made
494	* it stale has not yet committed. i.e. we are
495	* reallocating a busy extent. Skip this buffer and
496	* continue searching for an exact match.
497	*/
498	if (!(map->bm_flags & XBM_LIVESCAN))
499	ASSERT(bp->b_flags & XBF_STALE);
500	return 1;
501	}
502	return 0;
503	}
504
505	static const struct rhashtable_params xfs_buf_hash_params = {
506	.min_size = 32, /* empty AGs have minimal footprint */
507	.nelem_hint = 16,
508	.key_len = sizeof(xfs_daddr_t),
509	.key_offset = offsetof(struct xfs_buf, b_rhash_key),
510	.head_offset = offsetof(struct xfs_buf, b_rhash_head),
511	.automatic_shrinking = true,
512	.obj_cmpfn = _xfs_buf_obj_cmp,
513	};
514
515	int
516	xfs_buf_cache_init(
517	struct xfs_buf_cache *bch)
518	{
519	spin_lock_init(&bch->bc_lock);
520	return rhashtable_init(ht: &bch->bc_hash, params: &xfs_buf_hash_params);
521	}
522
523	void
524	xfs_buf_cache_destroy(
525	struct xfs_buf_cache *bch)
526	{
527	rhashtable_destroy(ht: &bch->bc_hash);
528	}
529
530	static int
531	xfs_buf_map_verify(
532	struct xfs_buftarg *btp,
533	struct xfs_buf_map *map)
534	{
535	xfs_daddr_t eofs;
536
537	/* Check for IOs smaller than the sector size / not sector aligned */
538	ASSERT(!(BBTOB(map->bm_len) < btp->bt_meta_sectorsize));
539	ASSERT(!(BBTOB(map->bm_bn) & (xfs_off_t)btp->bt_meta_sectormask));
540
541	/*
542	* Corrupted block numbers can get through to here, unfortunately, so we
543	* have to check that the buffer falls within the filesystem bounds.
544	*/
545	eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks);
546	if (map->bm_bn < 0 || map->bm_bn >= eofs) {
547	xfs_alert(btp->bt_mount,
548	"%s: daddr 0x%llx out of range, EOFS 0x%llx",
549	__func__, map->bm_bn, eofs);
550	WARN_ON(1);
551	return -EFSCORRUPTED;
552	}
553	return 0;
554	}
555
556	static int
557	xfs_buf_find_lock(
558	struct xfs_buf *bp,
559	xfs_buf_flags_t flags)
560	{
561	if (flags & XBF_TRYLOCK) {
562	if (!xfs_buf_trylock(bp)) {
563	XFS_STATS_INC(bp->b_mount, xb_busy_locked);
564	return -EAGAIN;
565	}
566	} else {
567	xfs_buf_lock(bp);
568	XFS_STATS_INC(bp->b_mount, xb_get_locked_waited);
569	}
570
571	/*
572	* if the buffer is stale, clear all the external state associated with
573	* it. We need to keep flags such as how we allocated the buffer memory
574	* intact here.
575	*/
576	if (bp->b_flags & XBF_STALE) {
577	if (flags & XBF_LIVESCAN) {
578	xfs_buf_unlock(bp);
579	return -ENOENT;
580	}
581	ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
582	bp->b_flags &= _XBF_KMEM | _XBF_PAGES;
583	bp->b_ops = NULL;
584	}
585	return 0;
586	}
587
588	static inline int
589	xfs_buf_lookup(
590	struct xfs_buf_cache *bch,
591	struct xfs_buf_map *map,
592	xfs_buf_flags_t flags,
593	struct xfs_buf **bpp)
594	{
595	struct xfs_buf *bp;
596	int error;
597
598	rcu_read_lock();
599	bp = rhashtable_lookup(ht: &bch->bc_hash, key: map, params: xfs_buf_hash_params);
600	if (!bp || !atomic_inc_not_zero(v: &bp->b_hold)) {
601	rcu_read_unlock();
602	return -ENOENT;
603	}
604	rcu_read_unlock();
605
606	error = xfs_buf_find_lock(bp, flags);
607	if (error) {
608	xfs_buf_rele(bp);
609	return error;
610	}
611
612	trace_xfs_buf_find(bp, flags, _RET_IP_);
613	*bpp = bp;
614	return 0;
615	}
616
617	/*
618	* Insert the new_bp into the hash table. This consumes the perag reference
619	* taken for the lookup regardless of the result of the insert.
620	*/
621	static int
622	xfs_buf_find_insert(
623	struct xfs_buftarg *btp,
624	struct xfs_buf_cache *bch,
625	struct xfs_perag *pag,
626	struct xfs_buf_map *cmap,
627	struct xfs_buf_map *map,
628	int nmaps,
629	xfs_buf_flags_t flags,
630	struct xfs_buf **bpp)
631	{
632	struct xfs_buf *new_bp;
633	struct xfs_buf *bp;
634	int error;
635
636	error = _xfs_buf_alloc(target: btp, map, nmaps, flags, bpp: &new_bp);
637	if (error)
638	goto out_drop_pag;
639
640	if (xfs_buftarg_is_mem(btp: new_bp->b_target)) {
641	error = xmbuf_map_page(bp: new_bp);
642	} else if (BBTOB(new_bp->b_length) >= PAGE_SIZE ||
643	xfs_buf_alloc_kmem(bp: new_bp, flags) < 0) {
644	/*
645	* For buffers that fit entirely within a single page, first
646	* attempt to allocate the memory from the heap to minimise
647	* memory usage. If we can't get heap memory for these small
648	* buffers, we fall back to using the page allocator.
649	*/
650	error = xfs_buf_alloc_pages(bp: new_bp, flags);
651	}
652	if (error)
653	goto out_free_buf;
654
655	spin_lock(lock: &bch->bc_lock);
656	bp = rhashtable_lookup_get_insert_fast(ht: &bch->bc_hash,
657	obj: &new_bp->b_rhash_head, params: xfs_buf_hash_params);
658	if (IS_ERR(ptr: bp)) {
659	error = PTR_ERR(ptr: bp);
660	spin_unlock(lock: &bch->bc_lock);
661	goto out_free_buf;
662	}
663	if (bp) {
664	/* found an existing buffer */
665	atomic_inc(v: &bp->b_hold);
666	spin_unlock(lock: &bch->bc_lock);
667	error = xfs_buf_find_lock(bp, flags);
668	if (error)
669	xfs_buf_rele(bp);
670	else
671	*bpp = bp;
672	goto out_free_buf;
673	}
674
675	/* The new buffer keeps the perag reference until it is freed. */
676	new_bp->b_pag = pag;
677	spin_unlock(lock: &bch->bc_lock);
678	*bpp = new_bp;
679	return 0;
680
681	out_free_buf:
682	xfs_buf_free(bp: new_bp);
683	out_drop_pag:
684	if (pag)
685	xfs_perag_put(pag);
686	return error;
687	}
688
689	static inline struct xfs_perag *
690	xfs_buftarg_get_pag(
691	struct xfs_buftarg *btp,
692	const struct xfs_buf_map *map)
693	{
694	struct xfs_mount *mp = btp->bt_mount;
695
696	if (xfs_buftarg_is_mem(btp))
697	return NULL;
698	return xfs_perag_get(mp, xfs_daddr_to_agno(mp, map->bm_bn));
699	}
700
701	static inline struct xfs_buf_cache *
702	xfs_buftarg_buf_cache(
703	struct xfs_buftarg *btp,
704	struct xfs_perag *pag)
705	{
706	if (pag)
707	return &pag->pag_bcache;
708	return btp->bt_cache;
709	}
710
711	/*
712	* Assembles a buffer covering the specified range. The code is optimised for
713	* cache hits, as metadata intensive workloads will see 3 orders of magnitude
714	* more hits than misses.
715	*/
716	int
717	xfs_buf_get_map(
718	struct xfs_buftarg *btp,
719	struct xfs_buf_map *map,
720	int nmaps,
721	xfs_buf_flags_t flags,
722	struct xfs_buf **bpp)
723	{
724	struct xfs_buf_cache *bch;
725	struct xfs_perag *pag;
726	struct xfs_buf *bp = NULL;
727	struct xfs_buf_map cmap = { .bm_bn = map[0].bm_bn };
728	int error;
729	int i;
730
731	if (flags & XBF_LIVESCAN)
732	cmap.bm_flags |= XBM_LIVESCAN;
733	for (i = 0; i < nmaps; i++)
734	cmap.bm_len += map[i].bm_len;
735
736	error = xfs_buf_map_verify(btp, map: &cmap);
737	if (error)
738	return error;
739
740	pag = xfs_buftarg_get_pag(btp, map: &cmap);
741	bch = xfs_buftarg_buf_cache(btp, pag);
742
743	error = xfs_buf_lookup(bch, map: &cmap, flags, bpp: &bp);
744	if (error && error != -ENOENT)
745	goto out_put_perag;
746
747	/* cache hits always outnumber misses by at least 10:1 */
748	if (unlikely(!bp)) {
749	XFS_STATS_INC(btp->bt_mount, xb_miss_locked);
750
751	if (flags & XBF_INCORE)
752	goto out_put_perag;
753
754	/* xfs_buf_find_insert() consumes the perag reference. */
755	error = xfs_buf_find_insert(btp, bch, pag, cmap: &cmap, map, nmaps,
756	flags, bpp: &bp);
757	if (error)
758	return error;
759	} else {
760	XFS_STATS_INC(btp->bt_mount, xb_get_locked);
761	if (pag)
762	xfs_perag_put(pag);
763	}
764
765	/* We do not hold a perag reference anymore. */
766	if (!bp->b_addr) {
767	error = _xfs_buf_map_pages(bp, flags);
768	if (unlikely(error)) {
769	xfs_warn_ratelimited(btp->bt_mount,
770	"%s: failed to map %u pages", __func__,
771	bp->b_page_count);
772	xfs_buf_relse(bp);
773	return error;
774	}
775	}
776
777	/*
778	* Clear b_error if this is a lookup from a caller that doesn't expect
779	* valid data to be found in the buffer.
780	*/
781	if (!(flags & XBF_READ))
782	xfs_buf_ioerror(bp, 0);
783
784	XFS_STATS_INC(btp->bt_mount, xb_get);
785	trace_xfs_buf_get(bp, flags, _RET_IP_);
786	*bpp = bp;
787	return 0;
788
789	out_put_perag:
790	if (pag)
791	xfs_perag_put(pag);
792	return error;
793	}
794
795	int
796	_xfs_buf_read(
797	struct xfs_buf *bp,
798	xfs_buf_flags_t flags)
799	{
800	ASSERT(!(flags & XBF_WRITE));
801	ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);
802
803	bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD | XBF_DONE);
804	bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
805
806	return xfs_buf_submit(bp);
807	}
808
809	/*
810	* Reverify a buffer found in cache without an attached ->b_ops.
811	*
812	* If the caller passed an ops structure and the buffer doesn't have ops
813	* assigned, set the ops and use it to verify the contents. If verification
814	* fails, clear XBF_DONE. We assume the buffer has no recorded errors and is
815	* already in XBF_DONE state on entry.
816	*
817	* Under normal operations, every in-core buffer is verified on read I/O
818	* completion. There are two scenarios that can lead to in-core buffers without
819	* an assigned ->b_ops. The first is during log recovery of buffers on a V4
820	* filesystem, though these buffers are purged at the end of recovery. The
821	* other is online repair, which intentionally reads with a NULL buffer ops to
822	* run several verifiers across an in-core buffer in order to establish buffer
823	* type. If repair can't establish that, the buffer will be left in memory
824	* with NULL buffer ops.
825	*/
826	int
827	xfs_buf_reverify(
828	struct xfs_buf *bp,
829	const struct xfs_buf_ops *ops)
830	{
831	ASSERT(bp->b_flags & XBF_DONE);
832	ASSERT(bp->b_error == 0);
833
834	if (!ops || bp->b_ops)
835	return 0;
836
837	bp->b_ops = ops;
838	bp->b_ops->verify_read(bp);
839	if (bp->b_error)
840	bp->b_flags &= ~XBF_DONE;
841	return bp->b_error;
842	}
843
844	int
845	xfs_buf_read_map(
846	struct xfs_buftarg *target,
847	struct xfs_buf_map *map,
848	int nmaps,
849	xfs_buf_flags_t flags,
850	struct xfs_buf **bpp,
851	const struct xfs_buf_ops *ops,
852	xfs_failaddr_t fa)
853	{
854	struct xfs_buf *bp;
855	int error;
856
857	flags |= XBF_READ;
858	*bpp = NULL;
859
860	error = xfs_buf_get_map(btp: target, map, nmaps, flags, bpp: &bp);
861	if (error)
862	return error;
863
864	trace_xfs_buf_read(bp, flags, _RET_IP_);
865
866	if (!(bp->b_flags & XBF_DONE)) {
867	/* Initiate the buffer read and wait. */
868	XFS_STATS_INC(target->bt_mount, xb_get_read);
869	bp->b_ops = ops;
870	error = _xfs_buf_read(bp, flags);
871
872	/* Readahead iodone already dropped the buffer, so exit. */
873	if (flags & XBF_ASYNC)
874	return 0;
875	} else {
876	/* Buffer already read; all we need to do is check it. */
877	error = xfs_buf_reverify(bp, ops);
878
879	/* Readahead already finished; drop the buffer and exit. */
880	if (flags & XBF_ASYNC) {
881	xfs_buf_relse(bp);
882	return 0;
883	}
884
885	/* We do not want read in the flags */
886	bp->b_flags &= ~XBF_READ;
887	ASSERT(bp->b_ops != NULL || ops == NULL);
888	}
889
890	/*
891	* If we've had a read error, then the contents of the buffer are
892	* invalid and should not be used. To ensure that a followup read tries
893	* to pull the buffer from disk again, we clear the XBF_DONE flag and
894	* mark the buffer stale. This ensures that anyone who has a current
895	* reference to the buffer will interpret it's contents correctly and
896	* future cache lookups will also treat it as an empty, uninitialised
897	* buffer.
898	*/
899	if (error) {
900	/*
901	* Check against log shutdown for error reporting because
902	* metadata writeback may require a read first and we need to
903	* report errors in metadata writeback until the log is shut
904	* down. High level transaction read functions already check
905	* against mount shutdown, anyway, so we only need to be
906	* concerned about low level IO interactions here.
907	*/
908	if (!xlog_is_shutdown(log: target->bt_mount->m_log))
909	xfs_buf_ioerror_alert(bp, fa: fa);
910
911	bp->b_flags &= ~XBF_DONE;
912	xfs_buf_stale(bp);
913	xfs_buf_relse(bp);
914
915	/* bad CRC means corrupted metadata */
916	if (error == -EFSBADCRC)
917	error = -EFSCORRUPTED;
918	return error;
919	}
920
921	*bpp = bp;
922	return 0;
923	}
924
925	/*
926	* If we are not low on memory then do the readahead in a deadlock
927	* safe manner.
928	*/
929	void
930	xfs_buf_readahead_map(
931	struct xfs_buftarg *target,
932	struct xfs_buf_map *map,
933	int nmaps,
934	const struct xfs_buf_ops *ops)
935	{
936	struct xfs_buf *bp;
937
938	/*
939	* Currently we don't have a good means or justification for performing
940	* xmbuf_map_page asynchronously, so we don't do readahead.
941	*/
942	if (xfs_buftarg_is_mem(btp: target))
943	return;
944
945	xfs_buf_read_map(target, map, nmaps,
946	XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD, bpp: &bp, ops,
947	__this_address);
948	}
949
950	/*
951	* Read an uncached buffer from disk. Allocates and returns a locked
952	* buffer containing the disk contents or nothing. Uncached buffers always have
953	* a cache index of XFS_BUF_DADDR_NULL so we can easily determine if the buffer
954	* is cached or uncached during fault diagnosis.
955	*/
956	int
957	xfs_buf_read_uncached(
958	struct xfs_buftarg *target,
959	xfs_daddr_t daddr,
960	size_t numblks,
961	xfs_buf_flags_t flags,
962	struct xfs_buf **bpp,
963	const struct xfs_buf_ops *ops)
964	{
965	struct xfs_buf *bp;
966	int error;
967
968	*bpp = NULL;
969
970	error = xfs_buf_get_uncached(target, numblks, flags, bpp: &bp);
971	if (error)
972	return error;
973
974	/* set up the buffer for a read IO */
975	ASSERT(bp->b_map_count == 1);
976	bp->b_rhash_key = XFS_BUF_DADDR_NULL;
977	bp->b_maps[0].bm_bn = daddr;
978	bp->b_flags |= XBF_READ;
979	bp->b_ops = ops;
980
981	xfs_buf_submit(bp);
982	if (bp->b_error) {
983	error = bp->b_error;
984	xfs_buf_relse(bp);
985	return error;
986	}
987
988	*bpp = bp;
989	return 0;
990	}
991
992	int
993	xfs_buf_get_uncached(
994	struct xfs_buftarg *target,
995	size_t numblks,
996	xfs_buf_flags_t flags,
997	struct xfs_buf **bpp)
998	{
999	int error;
1000	struct xfs_buf *bp;
1001	DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks);
1002
1003	*bpp = NULL;
1004
1005	/* flags might contain irrelevant bits, pass only what we care about */
1006	error = _xfs_buf_alloc(target, map: &map, nmaps: 1, flags: flags & XBF_NO_IOACCT, bpp: &bp);
1007	if (error)
1008	return error;
1009
1010	if (xfs_buftarg_is_mem(btp: bp->b_target))
1011	error = xmbuf_map_page(bp);
1012	else
1013	error = xfs_buf_alloc_pages(bp, flags);
1014	if (error)
1015	goto fail_free_buf;
1016
1017	error = _xfs_buf_map_pages(bp, flags: 0);
1018	if (unlikely(error)) {
1019	xfs_warn(target->bt_mount,
1020	"%s: failed to map pages", __func__);
1021	goto fail_free_buf;
1022	}
1023
1024	trace_xfs_buf_get_uncached(bp, _RET_IP_);
1025	*bpp = bp;
1026	return 0;
1027
1028	fail_free_buf:
1029	xfs_buf_free(bp);
1030	return error;
1031	}
1032
1033	/*
1034	* Increment reference count on buffer, to hold the buffer concurrently
1035	* with another thread which may release (free) the buffer asynchronously.
1036	* Must hold the buffer already to call this function.
1037	*/
1038	void
1039	xfs_buf_hold(
1040	struct xfs_buf *bp)
1041	{
1042	trace_xfs_buf_hold(bp, _RET_IP_);
1043	atomic_inc(v: &bp->b_hold);
1044	}
1045
1046	static void
1047	xfs_buf_rele_uncached(
1048	struct xfs_buf *bp)
1049	{
1050	ASSERT(list_empty(&bp->b_lru));
1051	if (atomic_dec_and_test(v: &bp->b_hold)) {
1052	xfs_buf_ioacct_dec(bp);
1053	xfs_buf_free(bp);
1054	}
1055	}
1056
1057	static void
1058	xfs_buf_rele_cached(
1059	struct xfs_buf *bp)
1060	{
1061	struct xfs_buftarg *btp = bp->b_target;
1062	struct xfs_perag *pag = bp->b_pag;
1063	struct xfs_buf_cache *bch = xfs_buftarg_buf_cache(btp, pag);
1064	bool release;
1065	bool freebuf = false;
1066
1067	trace_xfs_buf_rele(bp, _RET_IP_);
1068
1069	ASSERT(atomic_read(&bp->b_hold) > 0);
1070
1071	/*
1072	* We grab the b_lock here first to serialise racing xfs_buf_rele()
1073	* calls. The pag_buf_lock being taken on the last reference only
1074	* serialises against racing lookups in xfs_buf_find(). IOWs, the second
1075	* to last reference we drop here is not serialised against the last
1076	* reference until we take bp->b_lock. Hence if we don't grab b_lock
1077	* first, the last "release" reference can win the race to the lock and
1078	* free the buffer before the second-to-last reference is processed,
1079	* leading to a use-after-free scenario.
1080	*/
1081	spin_lock(lock: &bp->b_lock);
1082	release = atomic_dec_and_lock(&bp->b_hold, &bch->bc_lock);
1083	if (!release) {
1084	/*
1085	* Drop the in-flight state if the buffer is already on the LRU
1086	* and it holds the only reference. This is racy because we
1087	* haven't acquired the pag lock, but the use of _XBF_IN_FLIGHT
1088	* ensures the decrement occurs only once per-buf.
1089	*/
1090	if ((atomic_read(v: &bp->b_hold) == 1) && !list_empty(head: &bp->b_lru))
1091	__xfs_buf_ioacct_dec(bp);
1092	goto out_unlock;
1093	}
1094
1095	/* the last reference has been dropped ... */
1096	__xfs_buf_ioacct_dec(bp);
1097	if (!(bp->b_flags & XBF_STALE) && atomic_read(v: &bp->b_lru_ref)) {
1098	/*
1099	* If the buffer is added to the LRU take a new reference to the
1100	* buffer for the LRU and clear the (now stale) dispose list
1101	* state flag
1102	*/
1103	if (list_lru_add_obj(lru: &btp->bt_lru, item: &bp->b_lru)) {
1104	bp->b_state &= ~XFS_BSTATE_DISPOSE;
1105	atomic_inc(v: &bp->b_hold);
1106	}
1107	spin_unlock(lock: &bch->bc_lock);
1108	} else {
1109	/*
1110	* most of the time buffers will already be removed from the
1111	* LRU, so optimise that case by checking for the
1112	* XFS_BSTATE_DISPOSE flag indicating the last list the buffer
1113	* was on was the disposal list
1114	*/
1115	if (!(bp->b_state & XFS_BSTATE_DISPOSE)) {
1116	list_lru_del_obj(lru: &btp->bt_lru, item: &bp->b_lru);
1117	} else {
1118	ASSERT(list_empty(&bp->b_lru));
1119	}
1120
1121	ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1122	rhashtable_remove_fast(ht: &bch->bc_hash, obj: &bp->b_rhash_head,
1123	params: xfs_buf_hash_params);
1124	spin_unlock(lock: &bch->bc_lock);
1125	if (pag)
1126	xfs_perag_put(pag);
1127	freebuf = true;
1128	}
1129
1130	out_unlock:
1131	spin_unlock(lock: &bp->b_lock);
1132
1133	if (freebuf)
1134	xfs_buf_free(bp);
1135	}
1136
1137	/*
1138	* Release a hold on the specified buffer.
1139	*/
1140	void
1141	xfs_buf_rele(
1142	struct xfs_buf *bp)
1143	{
1144	trace_xfs_buf_rele(bp, _RET_IP_);
1145	if (xfs_buf_is_uncached(bp))
1146	xfs_buf_rele_uncached(bp);
1147	else
1148	xfs_buf_rele_cached(bp);
1149	}
1150
1151	/*
1152	* Lock a buffer object, if it is not already locked.
1153	*
1154	* If we come across a stale, pinned, locked buffer, we know that we are
1155	* being asked to lock a buffer that has been reallocated. Because it is
1156	* pinned, we know that the log has not been pushed to disk and hence it
1157	* will still be locked. Rather than continuing to have trylock attempts
1158	* fail until someone else pushes the log, push it ourselves before
1159	* returning. This means that the xfsaild will not get stuck trying
1160	* to push on stale inode buffers.
1161	*/
1162	int
1163	xfs_buf_trylock(
1164	struct xfs_buf *bp)
1165	{
1166	int locked;
1167
1168	locked = down_trylock(sem: &bp->b_sema) == 0;
1169	if (locked)
1170	trace_xfs_buf_trylock(bp, _RET_IP_);
1171	else
1172	trace_xfs_buf_trylock_fail(bp, _RET_IP_);
1173	return locked;
1174	}
1175
1176	/*
1177	* Lock a buffer object.
1178	*
1179	* If we come across a stale, pinned, locked buffer, we know that we
1180	* are being asked to lock a buffer that has been reallocated. Because
1181	* it is pinned, we know that the log has not been pushed to disk and
1182	* hence it will still be locked. Rather than sleeping until someone
1183	* else pushes the log, push it ourselves before trying to get the lock.
1184	*/
1185	void
1186	xfs_buf_lock(
1187	struct xfs_buf *bp)
1188	{
1189	trace_xfs_buf_lock(bp, _RET_IP_);
1190
1191	if (atomic_read(v: &bp->b_pin_count) && (bp->b_flags & XBF_STALE))
1192	xfs_log_force(mp: bp->b_mount, flags: 0);
1193	down(sem: &bp->b_sema);
1194
1195	trace_xfs_buf_lock_done(bp, _RET_IP_);
1196	}
1197
1198	void
1199	xfs_buf_unlock(
1200	struct xfs_buf *bp)
1201	{
1202	ASSERT(xfs_buf_islocked(bp));
1203
1204	up(sem: &bp->b_sema);
1205	trace_xfs_buf_unlock(bp, _RET_IP_);
1206	}
1207
1208	STATIC void
1209	xfs_buf_wait_unpin(
1210	struct xfs_buf *bp)
1211	{
1212	DECLARE_WAITQUEUE (wait, current);
1213
1214	if (atomic_read(v: &bp->b_pin_count) == 0)
1215	return;
1216
1217	add_wait_queue(wq_head: &bp->b_waiters, wq_entry: &wait);
1218	for (;;) {
1219	set_current_state(TASK_UNINTERRUPTIBLE);
1220	if (atomic_read(v: &bp->b_pin_count) == 0)
1221	break;
1222	io_schedule();
1223	}
1224	remove_wait_queue(wq_head: &bp->b_waiters, wq_entry: &wait);
1225	set_current_state(TASK_RUNNING);
1226	}
1227
1228	static void
1229	xfs_buf_ioerror_alert_ratelimited(
1230	struct xfs_buf *bp)
1231	{
1232	static unsigned long lasttime;
1233	static struct xfs_buftarg *lasttarg;
1234
1235	if (bp->b_target != lasttarg ||
1236	time_after(jiffies, (lasttime + 5*HZ))) {
1237	lasttime = jiffies;
1238	xfs_buf_ioerror_alert(bp, __this_address);
1239	}
1240	lasttarg = bp->b_target;
1241	}
1242
1243	/*
1244	* Account for this latest trip around the retry handler, and decide if
1245	* we've failed enough times to constitute a permanent failure.
1246	*/
1247	static bool
1248	xfs_buf_ioerror_permanent(
1249	struct xfs_buf *bp,
1250	struct xfs_error_cfg *cfg)
1251	{
1252	struct xfs_mount *mp = bp->b_mount;
1253
1254	if (cfg->max_retries != XFS_ERR_RETRY_FOREVER &&
1255	++bp->b_retries > cfg->max_retries)
1256	return true;
1257	if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
1258	time_after(jiffies, cfg->retry_timeout + bp->b_first_retry_time))
1259	return true;
1260
1261	/* At unmount we may treat errors differently */
1262	if (xfs_is_unmounting(mp) && mp->m_fail_unmount)
1263	return true;
1264
1265	return false;
1266	}
1267
1268	/*
1269	* On a sync write or shutdown we just want to stale the buffer and let the
1270	* caller handle the error in bp->b_error appropriately.
1271	*
1272	* If the write was asynchronous then no one will be looking for the error. If
1273	* this is the first failure of this type, clear the error state and write the
1274	* buffer out again. This means we always retry an async write failure at least
1275	* once, but we also need to set the buffer up to behave correctly now for
1276	* repeated failures.
1277	*
1278	* If we get repeated async write failures, then we take action according to the
1279	* error configuration we have been set up to use.
1280	*
1281	* Returns true if this function took care of error handling and the caller must
1282	* not touch the buffer again. Return false if the caller should proceed with
1283	* normal I/O completion handling.
1284	*/
1285	static bool
1286	xfs_buf_ioend_handle_error(
1287	struct xfs_buf *bp)
1288	{
1289	struct xfs_mount *mp = bp->b_mount;
1290	struct xfs_error_cfg *cfg;
1291
1292	/*
1293	* If we've already shutdown the journal because of I/O errors, there's
1294	* no point in giving this a retry.
1295	*/
1296	if (xlog_is_shutdown(log: mp->m_log))
1297	goto out_stale;
1298
1299	xfs_buf_ioerror_alert_ratelimited(bp);
1300
1301	/*
1302	* We're not going to bother about retrying this during recovery.
1303	* One strike!
1304	*/
1305	if (bp->b_flags & _XBF_LOGRECOVERY) {
1306	xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
1307	return false;
1308	}
1309
1310	/*
1311	* Synchronous writes will have callers process the error.
1312	*/
1313	if (!(bp->b_flags & XBF_ASYNC))
1314	goto out_stale;
1315
1316	trace_xfs_buf_iodone_async(bp, _RET_IP_);
1317
1318	cfg = xfs_error_get_cfg(mp, error_class: XFS_ERR_METADATA, error: bp->b_error);
1319	if (bp->b_last_error != bp->b_error ||
1320	!(bp->b_flags & (XBF_STALE | XBF_WRITE_FAIL))) {
1321	bp->b_last_error = bp->b_error;
1322	if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
1323	!bp->b_first_retry_time)
1324	bp->b_first_retry_time = jiffies;
1325	goto resubmit;
1326	}
1327
1328	/*
1329	* Permanent error - we need to trigger a shutdown if we haven't already
1330	* to indicate that inconsistency will result from this action.
1331	*/
1332	if (xfs_buf_ioerror_permanent(bp, cfg)) {
1333	xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
1334	goto out_stale;
1335	}
1336
1337	/* Still considered a transient error. Caller will schedule retries. */
1338	if (bp->b_flags & _XBF_INODES)
1339	xfs_buf_inode_io_fail(bp);
1340	else if (bp->b_flags & _XBF_DQUOTS)
1341	xfs_buf_dquot_io_fail(bp);
1342	else
1343	ASSERT(list_empty(&bp->b_li_list));
1344	xfs_buf_ioerror(bp, 0);
1345	xfs_buf_relse(bp);
1346	return true;
1347
1348	resubmit:
1349	xfs_buf_ioerror(bp, 0);
1350	bp->b_flags |= (XBF_DONE | XBF_WRITE_FAIL);
1351	xfs_buf_submit(bp);
1352	return true;
1353	out_stale:
1354	xfs_buf_stale(bp);
1355	bp->b_flags |= XBF_DONE;
1356	bp->b_flags &= ~XBF_WRITE;
1357	trace_xfs_buf_error_relse(bp, _RET_IP_);
1358	return false;
1359	}
1360
1361	static void
1362	xfs_buf_ioend(
1363	struct xfs_buf *bp)
1364	{
1365	trace_xfs_buf_iodone(bp, _RET_IP_);
1366
1367	/*
1368	* Pull in IO completion errors now. We are guaranteed to be running
1369	* single threaded, so we don't need the lock to read b_io_error.
1370	*/
1371	if (!bp->b_error && bp->b_io_error)
1372	xfs_buf_ioerror(bp, bp->b_io_error);
1373
1374	if (bp->b_flags & XBF_READ) {
1375	if (!bp->b_error && bp->b_ops)
1376	bp->b_ops->verify_read(bp);
1377	if (!bp->b_error)
1378	bp->b_flags |= XBF_DONE;
1379	} else {
1380	if (!bp->b_error) {
1381	bp->b_flags &= ~XBF_WRITE_FAIL;
1382	bp->b_flags |= XBF_DONE;
1383	}
1384
1385	if (unlikely(bp->b_error) && xfs_buf_ioend_handle_error(bp))
1386	return;
1387
1388	/* clear the retry state */
1389	bp->b_last_error = 0;
1390	bp->b_retries = 0;
1391	bp->b_first_retry_time = 0;
1392
1393	/*
1394	* Note that for things like remote attribute buffers, there may
1395	* not be a buffer log item here, so processing the buffer log
1396	* item must remain optional.
1397	*/
1398	if (bp->b_log_item)
1399	xfs_buf_item_done(bp);
1400
1401	if (bp->b_flags & _XBF_INODES)
1402	xfs_buf_inode_iodone(bp);
1403	else if (bp->b_flags & _XBF_DQUOTS)
1404	xfs_buf_dquot_iodone(bp);
1405
1406	}
1407
1408	bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD |
1409	_XBF_LOGRECOVERY);
1410
1411	if (bp->b_flags & XBF_ASYNC)
1412	xfs_buf_relse(bp);
1413	else
1414	complete(&bp->b_iowait);
1415	}
1416
1417	static void
1418	xfs_buf_ioend_work(
1419	struct work_struct *work)
1420	{
1421	struct xfs_buf *bp =
1422	container_of(work, struct xfs_buf, b_ioend_work);
1423
1424	xfs_buf_ioend(bp);
1425	}
1426
1427	static void
1428	xfs_buf_ioend_async(
1429	struct xfs_buf *bp)
1430	{
1431	INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);
1432	queue_work(wq: bp->b_mount->m_buf_workqueue, work: &bp->b_ioend_work);
1433	}
1434
1435	void
1436	__xfs_buf_ioerror(
1437	struct xfs_buf *bp,
1438	int error,
1439	xfs_failaddr_t failaddr)
1440	{
1441	ASSERT(error <= 0 && error >= -1000);
1442	bp->b_error = error;
1443	trace_xfs_buf_ioerror(bp, error, caller_ip: failaddr);
1444	}
1445
1446	void
1447	xfs_buf_ioerror_alert(
1448	struct xfs_buf *bp,
1449	xfs_failaddr_t func)
1450	{
1451	xfs_buf_alert_ratelimited(bp, rlmsg: "XFS: metadata IO error",
1452	fmt: "metadata I/O error in \"%pS\" at daddr 0x%llx len %d error %d",
1453	func, (uint64_t)xfs_buf_daddr(bp),
1454	bp->b_length, -bp->b_error);
1455	}
1456
1457	/*
1458	* To simulate an I/O failure, the buffer must be locked and held with at least
1459	* three references. The LRU reference is dropped by the stale call. The buf
1460	* item reference is dropped via ioend processing. The third reference is owned
1461	* by the caller and is dropped on I/O completion if the buffer is XBF_ASYNC.
1462	*/
1463	void
1464	xfs_buf_ioend_fail(
1465	struct xfs_buf *bp)
1466	{
1467	bp->b_flags &= ~XBF_DONE;
1468	xfs_buf_stale(bp);
1469	xfs_buf_ioerror(bp, -EIO);
1470	xfs_buf_ioend(bp);
1471	}
1472
1473	int
1474	xfs_bwrite(
1475	struct xfs_buf *bp)
1476	{
1477	int error;
1478
1479	ASSERT(xfs_buf_islocked(bp));
1480
1481	bp->b_flags |= XBF_WRITE;
1482	bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q |
1483	XBF_DONE);
1484
1485	error = xfs_buf_submit(bp);
1486	if (error)
1487	xfs_force_shutdown(bp->b_mount, SHUTDOWN_META_IO_ERROR);
1488	return error;
1489	}
1490
1491	static void
1492	xfs_buf_bio_end_io(
1493	struct bio *bio)
1494	{
1495	struct xfs_buf *bp = (struct xfs_buf *)bio->bi_private;
1496
1497	if (!bio->bi_status &&
1498	(bp->b_flags & XBF_WRITE) && (bp->b_flags & XBF_ASYNC) &&
1499	XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_IOERROR))
1500	bio->bi_status = BLK_STS_IOERR;
1501
1502	/*
1503	* don't overwrite existing errors - otherwise we can lose errors on
1504	* buffers that require multiple bios to complete.
1505	*/
1506	if (bio->bi_status) {
1507	int error = blk_status_to_errno(status: bio->bi_status);
1508
1509	cmpxchg(&bp->b_io_error, 0, error);
1510	}
1511
1512	if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
1513	invalidate_kernel_vmap_range(vaddr: bp->b_addr, size: xfs_buf_vmap_len(bp));
1514
1515	if (atomic_dec_and_test(v: &bp->b_io_remaining) == 1)
1516	xfs_buf_ioend_async(bp);
1517	bio_put(bio);
1518	}
1519
1520	static void
1521	xfs_buf_ioapply_map(
1522	struct xfs_buf *bp,
1523	int map,
1524	int *buf_offset,
1525	int *count,
1526	blk_opf_t op)
1527	{
1528	int page_index;
1529	unsigned int total_nr_pages = bp->b_page_count;
1530	int nr_pages;
1531	struct bio *bio;
1532	sector_t sector = bp->b_maps[map].bm_bn;
1533	int size;
1534	int offset;
1535
1536	/* skip the pages in the buffer before the start offset */
1537	page_index = 0;
1538	offset = *buf_offset;
1539	while (offset >= PAGE_SIZE) {
1540	page_index++;
1541	offset -= PAGE_SIZE;
1542	}
1543
1544	/*
1545	* Limit the IO size to the length of the current vector, and update the
1546	* remaining IO count for the next time around.
1547	*/
1548	size = min_t(int, BBTOB(bp->b_maps[map].bm_len), *count);
1549	*count -= size;
1550	*buf_offset += size;
1551
1552	next_chunk:
1553	atomic_inc(v: &bp->b_io_remaining);
1554	nr_pages = bio_max_segs(nr_segs: total_nr_pages);
1555
1556	bio = bio_alloc(bdev: bp->b_target->bt_bdev, nr_vecs: nr_pages, opf: op, GFP_NOIO);
1557	bio->bi_iter.bi_sector = sector;
1558	bio->bi_end_io = xfs_buf_bio_end_io;
1559	bio->bi_private = bp;
1560
1561	for (; size && nr_pages; nr_pages--, page_index++) {
1562	int rbytes, nbytes = PAGE_SIZE - offset;
1563
1564	if (nbytes > size)
1565	nbytes = size;
1566
1567	rbytes = bio_add_page(bio, page: bp->b_pages[page_index], len: nbytes,
1568	off: offset);
1569	if (rbytes < nbytes)
1570	break;
1571
1572	offset = 0;
1573	sector += BTOBB(nbytes);
1574	size -= nbytes;
1575	total_nr_pages--;
1576	}
1577
1578	if (likely(bio->bi_iter.bi_size)) {
1579	if (xfs_buf_is_vmapped(bp)) {
1580	flush_kernel_vmap_range(vaddr: bp->b_addr,
1581	size: xfs_buf_vmap_len(bp));
1582	}
1583	submit_bio(bio);
1584	if (size)
1585	goto next_chunk;
1586	} else {
1587	/*
1588	* This is guaranteed not to be the last io reference count
1589	* because the caller (xfs_buf_submit) holds a count itself.
1590	*/
1591	atomic_dec(v: &bp->b_io_remaining);
1592	xfs_buf_ioerror(bp, -EIO);
1593	bio_put(bio);
1594	}
1595
1596	}
1597
1598	STATIC void
1599	_xfs_buf_ioapply(
1600	struct xfs_buf *bp)
1601	{
1602	struct blk_plug plug;
1603	blk_opf_t op;
1604	int offset;
1605	int size;
1606	int i;
1607
1608	/*
1609	* Make sure we capture only current IO errors rather than stale errors
1610	* left over from previous use of the buffer (e.g. failed readahead).
1611	*/
1612	bp->b_error = 0;
1613
1614	if (bp->b_flags & XBF_WRITE) {
1615	op = REQ_OP_WRITE;
1616
1617	/*
1618	* Run the write verifier callback function if it exists. If
1619	* this function fails it will mark the buffer with an error and
1620	* the IO should not be dispatched.
1621	*/
1622	if (bp->b_ops) {
1623	bp->b_ops->verify_write(bp);
1624	if (bp->b_error) {
1625	xfs_force_shutdown(bp->b_mount,
1626	SHUTDOWN_CORRUPT_INCORE);
1627	return;
1628	}
1629	} else if (bp->b_rhash_key != XFS_BUF_DADDR_NULL) {
1630	struct xfs_mount *mp = bp->b_mount;
1631
1632	/*
1633	* non-crc filesystems don't attach verifiers during
1634	* log recovery, so don't warn for such filesystems.
1635	*/
1636	if (xfs_has_crc(mp)) {
1637	xfs_warn(mp,
1638	"%s: no buf ops on daddr 0x%llx len %d",
1639	__func__, xfs_buf_daddr(bp),
1640	bp->b_length);
1641	xfs_hex_dump(p: bp->b_addr,
1642	XFS_CORRUPTION_DUMP_LEN);
1643	dump_stack();
1644	}
1645	}
1646	} else {
1647	op = REQ_OP_READ;
1648	if (bp->b_flags & XBF_READ_AHEAD)
1649	op |= REQ_RAHEAD;
1650	}
1651
1652	/* we only use the buffer cache for meta-data */
1653	op |= REQ_META;
1654
1655	/* in-memory targets are directly mapped, no IO required. */
1656	if (xfs_buftarg_is_mem(btp: bp->b_target)) {
1657	xfs_buf_ioend(bp);
1658	return;
1659	}
1660
1661	/*
1662	* Walk all the vectors issuing IO on them. Set up the initial offset
1663	* into the buffer and the desired IO size before we start -
1664	* _xfs_buf_ioapply_vec() will modify them appropriately for each
1665	* subsequent call.
1666	*/
1667	offset = bp->b_offset;
1668	size = BBTOB(bp->b_length);
1669	blk_start_plug(&plug);
1670	for (i = 0; i < bp->b_map_count; i++) {
1671	xfs_buf_ioapply_map(bp, map: i, buf_offset: &offset, count: &size, op);
1672	if (bp->b_error)
1673	break;
1674	if (size <= 0)
1675	break; /* all done */
1676	}
1677	blk_finish_plug(&plug);
1678	}
1679
1680	/*
1681	* Wait for I/O completion of a sync buffer and return the I/O error code.
1682	*/
1683	static int
1684	xfs_buf_iowait(
1685	struct xfs_buf *bp)
1686	{
1687	ASSERT(!(bp->b_flags & XBF_ASYNC));
1688
1689	trace_xfs_buf_iowait(bp, _RET_IP_);
1690	wait_for_completion(&bp->b_iowait);
1691	trace_xfs_buf_iowait_done(bp, _RET_IP_);
1692
1693	return bp->b_error;
1694	}
1695
1696	/*
1697	* Buffer I/O submission path, read or write. Asynchronous submission transfers
1698	* the buffer lock ownership and the current reference to the IO. It is not
1699	* safe to reference the buffer after a call to this function unless the caller
1700	* holds an additional reference itself.
1701	*/
1702	static int
1703	__xfs_buf_submit(
1704	struct xfs_buf *bp,
1705	bool wait)
1706	{
1707	int error = 0;
1708
1709	trace_xfs_buf_submit(bp, _RET_IP_);
1710
1711	ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1712
1713	/*
1714	* On log shutdown we stale and complete the buffer immediately. We can
1715	* be called to read the superblock before the log has been set up, so
1716	* be careful checking the log state.
1717	*
1718	* Checking the mount shutdown state here can result in the log tail
1719	* moving inappropriately on disk as the log may not yet be shut down.
1720	* i.e. failing this buffer on mount shutdown can remove it from the AIL
1721	* and move the tail of the log forwards without having written this
1722	* buffer to disk. This corrupts the log tail state in memory, and
1723	* because the log may not be shut down yet, it can then be propagated
1724	* to disk before the log is shutdown. Hence we check log shutdown
1725	* state here rather than mount state to avoid corrupting the log tail
1726	* on shutdown.
1727	*/
1728	if (bp->b_mount->m_log &&
1729	xlog_is_shutdown(log: bp->b_mount->m_log)) {
1730	xfs_buf_ioend_fail(bp);
1731	return -EIO;
1732	}
1733
1734	/*
1735	* Grab a reference so the buffer does not go away underneath us. For
1736	* async buffers, I/O completion drops the callers reference, which
1737	* could occur before submission returns.
1738	*/
1739	xfs_buf_hold(bp);
1740
1741	if (bp->b_flags & XBF_WRITE)
1742	xfs_buf_wait_unpin(bp);
1743
1744	/* clear the internal error state to avoid spurious errors */
1745	bp->b_io_error = 0;
1746
1747	/*
1748	* Set the count to 1 initially, this will stop an I/O completion
1749	* callout which happens before we have started all the I/O from calling
1750	* xfs_buf_ioend too early.
1751	*/
1752	atomic_set(v: &bp->b_io_remaining, i: 1);
1753	if (bp->b_flags & XBF_ASYNC)
1754	xfs_buf_ioacct_inc(bp);
1755	_xfs_buf_ioapply(bp);
1756
1757	/*
1758	* If _xfs_buf_ioapply failed, we can get back here with only the IO
1759	* reference we took above. If we drop it to zero, run completion so
1760	* that we don't return to the caller with completion still pending.
1761	*/
1762	if (atomic_dec_and_test(v: &bp->b_io_remaining) == 1) {
1763	if (bp->b_error || !(bp->b_flags & XBF_ASYNC))
1764	xfs_buf_ioend(bp);
1765	else
1766	xfs_buf_ioend_async(bp);
1767	}
1768
1769	if (wait)
1770	error = xfs_buf_iowait(bp);
1771
1772	/*
1773	* Release the hold that keeps the buffer referenced for the entire
1774	* I/O. Note that if the buffer is async, it is not safe to reference
1775	* after this release.
1776	*/
1777	xfs_buf_rele(bp);
1778	return error;
1779	}
1780
1781	void *
1782	xfs_buf_offset(
1783	struct xfs_buf *bp,
1784	size_t offset)
1785	{
1786	struct page *page;
1787
1788	if (bp->b_addr)
1789	return bp->b_addr + offset;
1790
1791	page = bp->b_pages[offset >> PAGE_SHIFT];
1792	return page_address(page) + (offset & (PAGE_SIZE-1));
1793	}
1794
1795	void
1796	xfs_buf_zero(
1797	struct xfs_buf *bp,
1798	size_t boff,
1799	size_t bsize)
1800	{
1801	size_t bend;
1802
1803	bend = boff + bsize;
1804	while (boff < bend) {
1805	struct page *page;
1806	int page_index, page_offset, csize;
1807
1808	page_index = (boff + bp->b_offset) >> PAGE_SHIFT;
1809	page_offset = (boff + bp->b_offset) & ~PAGE_MASK;
1810	page = bp->b_pages[page_index];
1811	csize = min_t(size_t, PAGE_SIZE - page_offset,
1812	BBTOB(bp->b_length) - boff);
1813
1814	ASSERT((csize + page_offset) <= PAGE_SIZE);
1815
1816	memset(page_address(page) + page_offset, 0, csize);
1817
1818	boff += csize;
1819	}
1820	}
1821
1822	/*
1823	* Log a message about and stale a buffer that a caller has decided is corrupt.
1824	*
1825	* This function should be called for the kinds of metadata corruption that
1826	* cannot be detect from a verifier, such as incorrect inter-block relationship
1827	* data. Do /not/ call this function from a verifier function.
1828	*
1829	* The buffer must be XBF_DONE prior to the call. Afterwards, the buffer will
1830	* be marked stale, but b_error will not be set. The caller is responsible for
1831	* releasing the buffer or fixing it.
1832	*/
1833	void
1834	__xfs_buf_mark_corrupt(
1835	struct xfs_buf *bp,
1836	xfs_failaddr_t fa)
1837	{
1838	ASSERT(bp->b_flags & XBF_DONE);
1839
1840	xfs_buf_corruption_error(bp, fa);
1841	xfs_buf_stale(bp);
1842	}
1843
1844	/*
1845	* Handling of buffer targets (buftargs).
1846	*/
1847
1848	/*
1849	* Wait for any bufs with callbacks that have been submitted but have not yet
1850	* returned. These buffers will have an elevated hold count, so wait on those
1851	* while freeing all the buffers only held by the LRU.
1852	*/
1853	static enum lru_status
1854	xfs_buftarg_drain_rele(
1855	struct list_head *item,
1856	struct list_lru_one *lru,
1857	spinlock_t *lru_lock,
1858	void *arg)
1859
1860	{
1861	struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1862	struct list_head *dispose = arg;
1863
1864	if (atomic_read(v: &bp->b_hold) > 1) {
1865	/* need to wait, so skip it this pass */
1866	trace_xfs_buf_drain_buftarg(bp, _RET_IP_);
1867	return LRU_SKIP;
1868	}
1869	if (!spin_trylock(lock: &bp->b_lock))
1870	return LRU_SKIP;
1871
1872	/*
1873	* clear the LRU reference count so the buffer doesn't get
1874	* ignored in xfs_buf_rele().
1875	*/
1876	atomic_set(v: &bp->b_lru_ref, i: 0);
1877	bp->b_state |= XFS_BSTATE_DISPOSE;
1878	list_lru_isolate_move(list: lru, item, head: dispose);
1879	spin_unlock(lock: &bp->b_lock);
1880	return LRU_REMOVED;
1881	}
1882
1883	/*
1884	* Wait for outstanding I/O on the buftarg to complete.
1885	*/
1886	void
1887	xfs_buftarg_wait(
1888	struct xfs_buftarg *btp)
1889	{
1890	/*
1891	* First wait on the buftarg I/O count for all in-flight buffers to be
1892	* released. This is critical as new buffers do not make the LRU until
1893	* they are released.
1894	*
1895	* Next, flush the buffer workqueue to ensure all completion processing
1896	* has finished. Just waiting on buffer locks is not sufficient for
1897	* async IO as the reference count held over IO is not released until
1898	* after the buffer lock is dropped. Hence we need to ensure here that
1899	* all reference counts have been dropped before we start walking the
1900	* LRU list.
1901	*/
1902	while (percpu_counter_sum(fbc: &btp->bt_io_count))
1903	delay(ticks: 100);
1904	flush_workqueue(btp->bt_mount->m_buf_workqueue);
1905	}
1906
1907	void
1908	xfs_buftarg_drain(
1909	struct xfs_buftarg *btp)
1910	{
1911	LIST_HEAD(dispose);
1912	int loop = 0;
1913	bool write_fail = false;
1914
1915	xfs_buftarg_wait(btp);
1916
1917	/* loop until there is nothing left on the lru list. */
1918	while (list_lru_count(lru: &btp->bt_lru)) {
1919	list_lru_walk(lru: &btp->bt_lru, isolate: xfs_buftarg_drain_rele,
1920	cb_arg: &dispose, LONG_MAX);
1921
1922	while (!list_empty(head: &dispose)) {
1923	struct xfs_buf *bp;
1924	bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1925	list_del_init(entry: &bp->b_lru);
1926	if (bp->b_flags & XBF_WRITE_FAIL) {
1927	write_fail = true;
1928	xfs_buf_alert_ratelimited(bp,
1929	rlmsg: "XFS: Corruption Alert",
1930	fmt: "Corruption Alert: Buffer at daddr 0x%llx had permanent write failures!",
1931	(long long)xfs_buf_daddr(bp));
1932	}
1933	xfs_buf_rele(bp);
1934	}
1935	if (loop++ != 0)
1936	delay(ticks: 100);
1937	}
1938
1939	/*
1940	* If one or more failed buffers were freed, that means dirty metadata
1941	* was thrown away. This should only ever happen after I/O completion
1942	* handling has elevated I/O error(s) to permanent failures and shuts
1943	* down the journal.
1944	*/
1945	if (write_fail) {
1946	ASSERT(xlog_is_shutdown(btp->bt_mount->m_log));
1947	xfs_alert(btp->bt_mount,
1948	"Please run xfs_repair to determine the extent of the problem.");
1949	}
1950	}
1951
1952	static enum lru_status
1953	xfs_buftarg_isolate(
1954	struct list_head *item,
1955	struct list_lru_one *lru,
1956	spinlock_t *lru_lock,
1957	void *arg)
1958	{
1959	struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1960	struct list_head *dispose = arg;
1961
1962	/*
1963	* we are inverting the lru lock/bp->b_lock here, so use a trylock.
1964	* If we fail to get the lock, just skip it.
1965	*/
1966	if (!spin_trylock(lock: &bp->b_lock))
1967	return LRU_SKIP;
1968	/*
1969	* Decrement the b_lru_ref count unless the value is already
1970	* zero. If the value is already zero, we need to reclaim the
1971	* buffer, otherwise it gets another trip through the LRU.
1972	*/
1973	if (atomic_add_unless(v: &bp->b_lru_ref, a: -1, u: 0)) {
1974	spin_unlock(lock: &bp->b_lock);
1975	return LRU_ROTATE;
1976	}
1977
1978	bp->b_state |= XFS_BSTATE_DISPOSE;
1979	list_lru_isolate_move(list: lru, item, head: dispose);
1980	spin_unlock(lock: &bp->b_lock);
1981	return LRU_REMOVED;
1982	}
1983
1984	static unsigned long
1985	xfs_buftarg_shrink_scan(
1986	struct shrinker *shrink,
1987	struct shrink_control *sc)
1988	{
1989	struct xfs_buftarg *btp = shrink->private_data;
1990	LIST_HEAD(dispose);
1991	unsigned long freed;
1992
1993	freed = list_lru_shrink_walk(lru: &btp->bt_lru, sc,
1994	isolate: xfs_buftarg_isolate, cb_arg: &dispose);
1995
1996	while (!list_empty(head: &dispose)) {
1997	struct xfs_buf *bp;
1998	bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1999	list_del_init(entry: &bp->b_lru);
2000	xfs_buf_rele(bp);
2001	}
2002
2003	return freed;
2004	}
2005
2006	static unsigned long
2007	xfs_buftarg_shrink_count(
2008	struct shrinker *shrink,
2009	struct shrink_control *sc)
2010	{
2011	struct xfs_buftarg *btp = shrink->private_data;
2012	return list_lru_shrink_count(lru: &btp->bt_lru, sc);
2013	}
2014
2015	void
2016	xfs_destroy_buftarg(
2017	struct xfs_buftarg *btp)
2018	{
2019	shrinker_free(shrinker: btp->bt_shrinker);
2020	ASSERT(percpu_counter_sum(&btp->bt_io_count) == 0);
2021	percpu_counter_destroy(fbc: &btp->bt_io_count);
2022	list_lru_destroy(lru: &btp->bt_lru);
2023	}
2024
2025	void
2026	xfs_free_buftarg(
2027	struct xfs_buftarg *btp)
2028	{
2029	xfs_destroy_buftarg(btp);
2030	fs_put_dax(dax_dev: btp->bt_daxdev, holder: btp->bt_mount);
2031	/* the main block device is closed by kill_block_super */
2032	if (btp->bt_bdev != btp->bt_mount->m_super->s_bdev)
2033	bdev_fput(bdev_file: btp->bt_bdev_file);
2034	kfree(objp: btp);
2035	}
2036
2037	int
2038	xfs_setsize_buftarg(
2039	struct xfs_buftarg *btp,
2040	unsigned int sectorsize)
2041	{
2042	/* Set up metadata sector size info */
2043	btp->bt_meta_sectorsize = sectorsize;
2044	btp->bt_meta_sectormask = sectorsize - 1;
2045
2046	if (set_blocksize(bdev: btp->bt_bdev, size: sectorsize)) {
2047	xfs_warn(btp->bt_mount,
2048	"Cannot set_blocksize to %u on device %pg",
2049	sectorsize, btp->bt_bdev);
2050	return -EINVAL;
2051	}
2052
2053	return 0;
2054	}
2055
2056	int
2057	xfs_init_buftarg(
2058	struct xfs_buftarg *btp,
2059	size_t logical_sectorsize,
2060	const char *descr)
2061	{
2062	/* Set up device logical sector size mask */
2063	btp->bt_logical_sectorsize = logical_sectorsize;
2064	btp->bt_logical_sectormask = logical_sectorsize - 1;
2065
2066	/*
2067	* Buffer IO error rate limiting. Limit it to no more than 10 messages
2068	* per 30 seconds so as to not spam logs too much on repeated errors.
2069	*/
2070	ratelimit_state_init(rs: &btp->bt_ioerror_rl, interval: 30 * HZ,
2071	DEFAULT_RATELIMIT_BURST);
2072
2073	if (list_lru_init(&btp->bt_lru))
2074	return -ENOMEM;
2075	if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))
2076	goto out_destroy_lru;
2077
2078	btp->bt_shrinker =
2079	shrinker_alloc(SHRINKER_NUMA_AWARE, fmt: "xfs-buf:%s", descr);
2080	if (!btp->bt_shrinker)
2081	goto out_destroy_io_count;
2082	btp->bt_shrinker->count_objects = xfs_buftarg_shrink_count;
2083	btp->bt_shrinker->scan_objects = xfs_buftarg_shrink_scan;
2084	btp->bt_shrinker->private_data = btp;
2085	shrinker_register(shrinker: btp->bt_shrinker);
2086	return 0;
2087
2088	out_destroy_io_count:
2089	percpu_counter_destroy(fbc: &btp->bt_io_count);
2090	out_destroy_lru:
2091	list_lru_destroy(lru: &btp->bt_lru);
2092	return -ENOMEM;
2093	}
2094
2095	struct xfs_buftarg *
2096	xfs_alloc_buftarg(
2097	struct xfs_mount *mp,
2098	struct file *bdev_file)
2099	{
2100	struct xfs_buftarg *btp;
2101	const struct dax_holder_operations *ops = NULL;
2102
2103	#if defined(CONFIG_FS_DAX) && defined(CONFIG_MEMORY_FAILURE)
2104	ops = &xfs_dax_holder_operations;
2105	#endif
2106	btp = kzalloc(size: sizeof(*btp), GFP_KERNEL | __GFP_NOFAIL);
2107
2108	btp->bt_mount = mp;
2109	btp->bt_bdev_file = bdev_file;
2110	btp->bt_bdev = file_bdev(bdev_file);
2111	btp->bt_dev = btp->bt_bdev->bd_dev;
2112	btp->bt_daxdev = fs_dax_get_by_bdev(bdev: btp->bt_bdev, start_off: &btp->bt_dax_part_off,
2113	holder: mp, ops);
2114
2115	/*
2116	* When allocating the buftargs we have not yet read the super block and
2117	* thus don't know the file system sector size yet.
2118	*/
2119	if (xfs_setsize_buftarg(btp, sectorsize: bdev_logical_block_size(bdev: btp->bt_bdev)))
2120	goto error_free;
2121	if (xfs_init_buftarg(btp, logical_sectorsize: bdev_logical_block_size(bdev: btp->bt_bdev),
2122	descr: mp->m_super->s_id))
2123	goto error_free;
2124
2125	return btp;
2126
2127	error_free:
2128	kfree(objp: btp);
2129	return NULL;
2130	}
2131
2132	static inline void
2133	xfs_buf_list_del(
2134	struct xfs_buf *bp)
2135	{
2136	list_del_init(entry: &bp->b_list);
2137	wake_up_var(var: &bp->b_list);
2138	}
2139
2140	/*
2141	* Cancel a delayed write list.
2142	*
2143	* Remove each buffer from the list, clear the delwri queue flag and drop the
2144	* associated buffer reference.
2145	*/
2146	void
2147	xfs_buf_delwri_cancel(
2148	struct list_head *list)
2149	{
2150	struct xfs_buf *bp;
2151
2152	while (!list_empty(head: list)) {
2153	bp = list_first_entry(list, struct xfs_buf, b_list);
2154
2155	xfs_buf_lock(bp);
2156	bp->b_flags &= ~_XBF_DELWRI_Q;
2157	xfs_buf_list_del(bp);
2158	xfs_buf_relse(bp);
2159	}
2160	}
2161
2162	/*
2163	* Add a buffer to the delayed write list.
2164	*
2165	* This queues a buffer for writeout if it hasn't already been. Note that
2166	* neither this routine nor the buffer list submission functions perform
2167	* any internal synchronization. It is expected that the lists are thread-local
2168	* to the callers.
2169	*
2170	* Returns true if we queued up the buffer, or false if it already had
2171	* been on the buffer list.
2172	*/
2173	bool
2174	xfs_buf_delwri_queue(
2175	struct xfs_buf *bp,
2176	struct list_head *list)
2177	{
2178	ASSERT(xfs_buf_islocked(bp));
2179	ASSERT(!(bp->b_flags & XBF_READ));
2180
2181	/*
2182	* If the buffer is already marked delwri it already is queued up
2183	* by someone else for imediate writeout. Just ignore it in that
2184	* case.
2185	*/
2186	if (bp->b_flags & _XBF_DELWRI_Q) {
2187	trace_xfs_buf_delwri_queued(bp, _RET_IP_);
2188	return false;
2189	}
2190
2191	trace_xfs_buf_delwri_queue(bp, _RET_IP_);
2192
2193	/*
2194	* If a buffer gets written out synchronously or marked stale while it
2195	* is on a delwri list we lazily remove it. To do this, the other party
2196	* clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
2197	* It remains referenced and on the list. In a rare corner case it
2198	* might get readded to a delwri list after the synchronous writeout, in
2199	* which case we need just need to re-add the flag here.
2200	*/
2201	bp->b_flags |= _XBF_DELWRI_Q;
2202	if (list_empty(head: &bp->b_list)) {
2203	atomic_inc(v: &bp->b_hold);
2204	list_add_tail(new: &bp->b_list, head: list);
2205	}
2206
2207	return true;
2208	}
2209
2210	/*
2211	* Queue a buffer to this delwri list as part of a data integrity operation.
2212	* If the buffer is on any other delwri list, we'll wait for that to clear
2213	* so that the caller can submit the buffer for IO and wait for the result.
2214	* Callers must ensure the buffer is not already on the list.
2215	*/
2216	void
2217	xfs_buf_delwri_queue_here(
2218	struct xfs_buf *bp,
2219	struct list_head *buffer_list)
2220	{
2221	/*
2222	* We need this buffer to end up on the /caller's/ delwri list, not any
2223	* old list. This can happen if the buffer is marked stale (which
2224	* clears DELWRI_Q) after the AIL queues the buffer to its list but
2225	* before the AIL has a chance to submit the list.
2226	*/
2227	while (!list_empty(head: &bp->b_list)) {
2228	xfs_buf_unlock(bp);
2229	wait_var_event(&bp->b_list, list_empty(&bp->b_list));
2230	xfs_buf_lock(bp);
2231	}
2232
2233	ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
2234
2235	xfs_buf_delwri_queue(bp, list: buffer_list);
2236	}
2237
2238	/*
2239	* Compare function is more complex than it needs to be because
2240	* the return value is only 32 bits and we are doing comparisons
2241	* on 64 bit values
2242	*/
2243	static int
2244	xfs_buf_cmp(
2245	void *priv,
2246	const struct list_head *a,
2247	const struct list_head *b)
2248	{
2249	struct xfs_buf *ap = container_of(a, struct xfs_buf, b_list);
2250	struct xfs_buf *bp = container_of(b, struct xfs_buf, b_list);
2251	xfs_daddr_t diff;
2252
2253	diff = ap->b_maps[0].bm_bn - bp->b_maps[0].bm_bn;
2254	if (diff < 0)
2255	return -1;
2256	if (diff > 0)
2257	return 1;
2258	return 0;
2259	}
2260
2261	/*
2262	* Submit buffers for write. If wait_list is specified, the buffers are
2263	* submitted using sync I/O and placed on the wait list such that the caller can
2264	* iowait each buffer. Otherwise async I/O is used and the buffers are released
2265	* at I/O completion time. In either case, buffers remain locked until I/O
2266	* completes and the buffer is released from the queue.
2267	*/
2268	static int
2269	xfs_buf_delwri_submit_buffers(
2270	struct list_head *buffer_list,
2271	struct list_head *wait_list)
2272	{
2273	struct xfs_buf *bp, *n;
2274	int pinned = 0;
2275	struct blk_plug plug;
2276
2277	list_sort(NULL, head: buffer_list, cmp: xfs_buf_cmp);
2278
2279	blk_start_plug(&plug);
2280	list_for_each_entry_safe(bp, n, buffer_list, b_list) {
2281	if (!wait_list) {
2282	if (!xfs_buf_trylock(bp))
2283	continue;
2284	if (xfs_buf_ispinned(bp)) {
2285	xfs_buf_unlock(bp);
2286	pinned++;
2287	continue;
2288	}
2289	} else {
2290	xfs_buf_lock(bp);
2291	}
2292
2293	/*
2294	* Someone else might have written the buffer synchronously or
2295	* marked it stale in the meantime. In that case only the
2296	* _XBF_DELWRI_Q flag got cleared, and we have to drop the
2297	* reference and remove it from the list here.
2298	*/
2299	if (!(bp->b_flags & _XBF_DELWRI_Q)) {
2300	xfs_buf_list_del(bp);
2301	xfs_buf_relse(bp);
2302	continue;
2303	}
2304
2305	trace_xfs_buf_delwri_split(bp, _RET_IP_);
2306
2307	/*
2308	* If we have a wait list, each buffer (and associated delwri
2309	* queue reference) transfers to it and is submitted
2310	* synchronously. Otherwise, drop the buffer from the delwri
2311	* queue and submit async.
2312	*/
2313	bp->b_flags &= ~_XBF_DELWRI_Q;
2314	bp->b_flags |= XBF_WRITE;
2315	if (wait_list) {
2316	bp->b_flags &= ~XBF_ASYNC;
2317	list_move_tail(list: &bp->b_list, head: wait_list);
2318	} else {
2319	bp->b_flags |= XBF_ASYNC;
2320	xfs_buf_list_del(bp);
2321	}
2322	__xfs_buf_submit(bp, wait: false);
2323	}
2324	blk_finish_plug(&plug);
2325
2326	return pinned;
2327	}
2328
2329	/*
2330	* Write out a buffer list asynchronously.
2331	*
2332	* This will take the @buffer_list, write all non-locked and non-pinned buffers
2333	* out and not wait for I/O completion on any of the buffers. This interface
2334	* is only safely useable for callers that can track I/O completion by higher
2335	* level means, e.g. AIL pushing as the @buffer_list is consumed in this
2336	* function.
2337	*
2338	* Note: this function will skip buffers it would block on, and in doing so
2339	* leaves them on @buffer_list so they can be retried on a later pass. As such,
2340	* it is up to the caller to ensure that the buffer list is fully submitted or
2341	* cancelled appropriately when they are finished with the list. Failure to
2342	* cancel or resubmit the list until it is empty will result in leaked buffers
2343	* at unmount time.
2344	*/
2345	int
2346	xfs_buf_delwri_submit_nowait(
2347	struct list_head *buffer_list)
2348	{
2349	return xfs_buf_delwri_submit_buffers(buffer_list, NULL);
2350	}
2351
2352	/*
2353	* Write out a buffer list synchronously.
2354	*
2355	* This will take the @buffer_list, write all buffers out and wait for I/O
2356	* completion on all of the buffers. @buffer_list is consumed by the function,
2357	* so callers must have some other way of tracking buffers if they require such
2358	* functionality.
2359	*/
2360	int
2361	xfs_buf_delwri_submit(
2362	struct list_head *buffer_list)
2363	{
2364	LIST_HEAD (wait_list);
2365	int error = 0, error2;
2366	struct xfs_buf *bp;
2367
2368	xfs_buf_delwri_submit_buffers(buffer_list, wait_list: &wait_list);
2369
2370	/* Wait for IO to complete. */
2371	while (!list_empty(head: &wait_list)) {
2372	bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
2373
2374	xfs_buf_list_del(bp);
2375
2376	/*
2377	* Wait on the locked buffer, check for errors and unlock and
2378	* release the delwri queue reference.
2379	*/
2380	error2 = xfs_buf_iowait(bp);
2381	xfs_buf_relse(bp);
2382	if (!error)
2383	error = error2;
2384	}
2385
2386	return error;
2387	}
2388
2389	/*
2390	* Push a single buffer on a delwri queue.
2391	*
2392	* The purpose of this function is to submit a single buffer of a delwri queue
2393	* and return with the buffer still on the original queue. The waiting delwri
2394	* buffer submission infrastructure guarantees transfer of the delwri queue
2395	* buffer reference to a temporary wait list. We reuse this infrastructure to
2396	* transfer the buffer back to the original queue.
2397	*
2398	* Note the buffer transitions from the queued state, to the submitted and wait
2399	* listed state and back to the queued state during this call. The buffer
2400	* locking and queue management logic between _delwri_pushbuf() and
2401	* _delwri_queue() guarantee that the buffer cannot be queued to another list
2402	* before returning.
2403	*/
2404	int
2405	xfs_buf_delwri_pushbuf(
2406	struct xfs_buf *bp,
2407	struct list_head *buffer_list)
2408	{
2409	LIST_HEAD (submit_list);
2410	int error;
2411
2412	ASSERT(bp->b_flags & _XBF_DELWRI_Q);
2413
2414	trace_xfs_buf_delwri_pushbuf(bp, _RET_IP_);
2415
2416	/*
2417	* Isolate the buffer to a new local list so we can submit it for I/O
2418	* independently from the rest of the original list.
2419	*/
2420	xfs_buf_lock(bp);
2421	list_move(list: &bp->b_list, head: &submit_list);
2422	xfs_buf_unlock(bp);
2423
2424	/*
2425	* Delwri submission clears the DELWRI_Q buffer flag and returns with
2426	* the buffer on the wait list with the original reference. Rather than
2427	* bounce the buffer from a local wait list back to the original list
2428	* after I/O completion, reuse the original list as the wait list.
2429	*/
2430	xfs_buf_delwri_submit_buffers(buffer_list: &submit_list, wait_list: buffer_list);
2431
2432	/*
2433	* The buffer is now locked, under I/O and wait listed on the original
2434	* delwri queue. Wait for I/O completion, restore the DELWRI_Q flag and
2435	* return with the buffer unlocked and on the original queue.
2436	*/
2437	error = xfs_buf_iowait(bp);
2438	bp->b_flags |= _XBF_DELWRI_Q;
2439	xfs_buf_unlock(bp);
2440
2441	return error;
2442	}
2443
2444	void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
2445	{
2446	/*
2447	* Set the lru reference count to 0 based on the error injection tag.
2448	* This allows userspace to disrupt buffer caching for debug/testing
2449	* purposes.
2450	*/
2451	if (XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_LRU_REF))
2452	lru_ref = 0;
2453
2454	atomic_set(v: &bp->b_lru_ref, i: lru_ref);
2455	}
2456
2457	/*
2458	* Verify an on-disk magic value against the magic value specified in the
2459	* verifier structure. The verifier magic is in disk byte order so the caller is
2460	* expected to pass the value directly from disk.
2461	*/
2462	bool
2463	xfs_verify_magic(
2464	struct xfs_buf *bp,
2465	__be32 dmagic)
2466	{
2467	struct xfs_mount *mp = bp->b_mount;
2468	int idx;
2469
2470	idx = xfs_has_crc(mp);
2471	if (WARN_ON(!bp->b_ops || !bp->b_ops->magic[idx]))
2472	return false;
2473	return dmagic == bp->b_ops->magic[idx];
2474	}
2475	/*
2476	* Verify an on-disk magic value against the magic value specified in the
2477	* verifier structure. The verifier magic is in disk byte order so the caller is
2478	* expected to pass the value directly from disk.
2479	*/
2480	bool
2481	xfs_verify_magic16(
2482	struct xfs_buf *bp,
2483	__be16 dmagic)
2484	{
2485	struct xfs_mount *mp = bp->b_mount;
2486	int idx;
2487
2488	idx = xfs_has_crc(mp);
2489	if (WARN_ON(!bp->b_ops || !bp->b_ops->magic16[idx]))
2490	return false;
2491	return dmagic == bp->b_ops->magic16[idx];
2492	}
2493