1	/*
2	* An async IO implementation for Linux
3	* Written by Benjamin LaHaise <bcrl@kvack.org>
4	*
5	* Implements an efficient asynchronous io interface.
6	*
7	* Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved.
8	* Copyright 2018 Christoph Hellwig.
9	*
10	* See ../COPYING for licensing terms.
11	*/
12	#define pr_fmt(fmt) "%s: " fmt, __func__
13
14	#include <linux/kernel.h>
15	#include <linux/init.h>
16	#include <linux/errno.h>
17	#include <linux/time.h>
18	#include <linux/aio_abi.h>
19	#include <linux/export.h>
20	#include <linux/syscalls.h>
21	#include <linux/backing-dev.h>
22	#include <linux/refcount.h>
23	#include <linux/uio.h>
24
25	#include <linux/sched/signal.h>
26	#include <linux/fs.h>
27	#include <linux/file.h>
28	#include <linux/mm.h>
29	#include <linux/mman.h>
30	#include <linux/percpu.h>
31	#include <linux/slab.h>
32	#include <linux/timer.h>
33	#include <linux/aio.h>
34	#include <linux/highmem.h>
35	#include <linux/workqueue.h>
36	#include <linux/security.h>
37	#include <linux/eventfd.h>
38	#include <linux/blkdev.h>
39	#include <linux/compat.h>
40	#include <linux/migrate.h>
41	#include <linux/ramfs.h>
42	#include <linux/percpu-refcount.h>
43	#include <linux/mount.h>
44	#include <linux/pseudo_fs.h>
45
46	#include <linux/uaccess.h>
47	#include <linux/nospec.h>
48
49	#include "internal.h"
50
51	#define KIOCB_KEY 0
52
53	#define AIO_RING_MAGIC 0xa10a10a1
54	#define AIO_RING_COMPAT_FEATURES 1
55	#define AIO_RING_INCOMPAT_FEATURES 0
56	struct aio_ring {
57	unsigned id; /* kernel internal index number */
58	unsigned nr; /* number of io_events */
59	unsigned head; /* Written to by userland or under ring_lock
60	* mutex by aio_read_events_ring(). */
61	unsigned tail;
62
63	unsigned magic;
64	unsigned compat_features;
65	unsigned incompat_features;
66	unsigned header_length; /* size of aio_ring */
67
68
69	struct io_event io_events[];
70	}; /* 128 bytes + ring size */
71
72	/*
73	* Plugging is meant to work with larger batches of IOs. If we don't
74	* have more than the below, then don't bother setting up a plug.
75	*/
76	#define AIO_PLUG_THRESHOLD 2
77
78	#define AIO_RING_PAGES 8
79
80	struct kioctx_table {
81	struct rcu_head rcu;
82	unsigned nr;
83	struct kioctx __rcu *table[] __counted_by(nr);
84	};
85
86	struct kioctx_cpu {
87	unsigned reqs_available;
88	};
89
90	struct ctx_rq_wait {
91	struct completion comp;
92	atomic_t count;
93	};
94
95	struct kioctx {
96	struct percpu_ref users;
97	atomic_t dead;
98
99	struct percpu_ref reqs;
100
101	unsigned long user_id;
102
103	struct __percpu kioctx_cpu *cpu;
104
105	/*
106	* For percpu reqs_available, number of slots we move to/from global
107	* counter at a time:
108	*/
109	unsigned req_batch;
110	/*
111	* This is what userspace passed to io_setup(), it's not used for
112	* anything but counting against the global max_reqs quota.
113	*
114	* The real limit is nr_events - 1, which will be larger (see
115	* aio_setup_ring())
116	*/
117	unsigned max_reqs;
118
119	/* Size of ringbuffer, in units of struct io_event */
120	unsigned nr_events;
121
122	unsigned long mmap_base;
123	unsigned long mmap_size;
124
125	struct page **ring_pages;
126	long nr_pages;
127
128	struct rcu_work free_rwork; /* see free_ioctx() */
129
130	/*
131	* signals when all in-flight requests are done
132	*/
133	struct ctx_rq_wait *rq_wait;
134
135	struct {
136	/*
137	* This counts the number of available slots in the ringbuffer,
138	* so we avoid overflowing it: it's decremented (if positive)
139	* when allocating a kiocb and incremented when the resulting
140	* io_event is pulled off the ringbuffer.
141	*
142	* We batch accesses to it with a percpu version.
143	*/
144	atomic_t reqs_available;
145	} ____cacheline_aligned_in_smp;
146
147	struct {
148	spinlock_t ctx_lock;
149	struct list_head active_reqs; /* used for cancellation */
150	} ____cacheline_aligned_in_smp;
151
152	struct {
153	struct mutex ring_lock;
154	wait_queue_head_t wait;
155	} ____cacheline_aligned_in_smp;
156
157	struct {
158	unsigned tail;
159	unsigned completed_events;
160	spinlock_t completion_lock;
161	} ____cacheline_aligned_in_smp;
162
163	struct page *internal_pages[AIO_RING_PAGES];
164	struct file *aio_ring_file;
165
166	unsigned id;
167	};
168
169	/*
170	* First field must be the file pointer in all the
171	* iocb unions! See also 'struct kiocb' in <linux/fs.h>
172	*/
173	struct fsync_iocb {
174	struct file *file;
175	struct work_struct work;
176	bool datasync;
177	struct cred *creds;
178	};
179
180	struct poll_iocb {
181	struct file *file;
182	struct wait_queue_head *head;
183	__poll_t events;
184	bool cancelled;
185	bool work_scheduled;
186	bool work_need_resched;
187	struct wait_queue_entry wait;
188	struct work_struct work;
189	};
190
191	/*
192	* NOTE! Each of the iocb union members has the file pointer
193	* as the first entry in their struct definition. So you can
194	* access the file pointer through any of the sub-structs,
195	* or directly as just 'ki_filp' in this struct.
196	*/
197	struct aio_kiocb {
198	union {
199	struct file *ki_filp;
200	struct kiocb rw;
201	struct fsync_iocb fsync;
202	struct poll_iocb poll;
203	};
204
205	struct kioctx *ki_ctx;
206	kiocb_cancel_fn *ki_cancel;
207
208	struct io_event ki_res;
209
210	struct list_head ki_list; /* the aio core uses this
211	* for cancellation */
212	refcount_t ki_refcnt;
213
214	/*
215	* If the aio_resfd field of the userspace iocb is not zero,
216	* this is the underlying eventfd context to deliver events to.
217	*/
218	struct eventfd_ctx *ki_eventfd;
219	};
220
221	/*------ sysctl variables----*/
222	static DEFINE_SPINLOCK(aio_nr_lock);
223	static unsigned long aio_nr; /* current system wide number of aio requests */
224	static unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
225	/*----end sysctl variables---*/
226	#ifdef CONFIG_SYSCTL
227	static struct ctl_table aio_sysctls[] = {
228	{
229	.procname = "aio-nr",
230	.data = &aio_nr,
231	.maxlen = sizeof(aio_nr),
232	.mode = 0444,
233	.proc_handler = proc_doulongvec_minmax,
234	},
235	{
236	.procname = "aio-max-nr",
237	.data = &aio_max_nr,
238	.maxlen = sizeof(aio_max_nr),
239	.mode = 0644,
240	.proc_handler = proc_doulongvec_minmax,
241	},
242	{}
243	};
244
245	static void __init aio_sysctl_init(void)
246	{
247	register_sysctl_init("fs", aio_sysctls);
248	}
249	#else
250	#define aio_sysctl_init() do { } while (0)
251	#endif
252
253	static struct kmem_cache *kiocb_cachep;
254	static struct kmem_cache *kioctx_cachep;
255
256	static struct vfsmount *aio_mnt;
257
258	static const struct file_operations aio_ring_fops;
259	static const struct address_space_operations aio_ctx_aops;
260
261	static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
262	{
263	struct file *file;
264	struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
265	if (IS_ERR(ptr: inode))
266	return ERR_CAST(ptr: inode);
267
268	inode->i_mapping->a_ops = &aio_ctx_aops;
269	inode->i_mapping->private_data = ctx;
270	inode->i_size = PAGE_SIZE * nr_pages;
271
272	file = alloc_file_pseudo(inode, aio_mnt, "[aio]",
273	O_RDWR, &aio_ring_fops);
274	if (IS_ERR(ptr: file))
275	iput(inode);
276	return file;
277	}
278
279	static int aio_init_fs_context(struct fs_context *fc)
280	{
281	if (!init_pseudo(fc, AIO_RING_MAGIC))
282	return -ENOMEM;
283	fc->s_iflags |= SB_I_NOEXEC;
284	return 0;
285	}
286
287	/* aio_setup
288	* Creates the slab caches used by the aio routines, panic on
289	* failure as this is done early during the boot sequence.
290	*/
291	static int __init aio_setup(void)
292	{
293	static struct file_system_type aio_fs = {
294	.name = "aio",
295	.init_fs_context = aio_init_fs_context,
296	.kill_sb = kill_anon_super,
297	};
298	aio_mnt = kern_mount(&aio_fs);
299	if (IS_ERR(ptr: aio_mnt))
300	panic(fmt: "Failed to create aio fs mount.");
301
302	kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
303	kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
304	aio_sysctl_init();
305	return 0;
306	}
307	__initcall(aio_setup);
308
309	static void put_aio_ring_file(struct kioctx *ctx)
310	{
311	struct file *aio_ring_file = ctx->aio_ring_file;
312	struct address_space *i_mapping;
313
314	if (aio_ring_file) {
315	truncate_setsize(inode: file_inode(f: aio_ring_file), newsize: 0);
316
317	/* Prevent further access to the kioctx from migratepages */
318	i_mapping = aio_ring_file->f_mapping;
319	spin_lock(lock: &i_mapping->private_lock);
320	i_mapping->private_data = NULL;
321	ctx->aio_ring_file = NULL;
322	spin_unlock(lock: &i_mapping->private_lock);
323
324	fput(aio_ring_file);
325	}
326	}
327
328	static void aio_free_ring(struct kioctx *ctx)
329	{
330	int i;
331
332	/* Disconnect the kiotx from the ring file. This prevents future
333	* accesses to the kioctx from page migration.
334	*/
335	put_aio_ring_file(ctx);
336
337	for (i = 0; i < ctx->nr_pages; i++) {
338	struct page *page;
339	pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
340	page_count(ctx->ring_pages[i]));
341	page = ctx->ring_pages[i];
342	if (!page)
343	continue;
344	ctx->ring_pages[i] = NULL;
345	put_page(page);
346	}
347
348	if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
349	kfree(objp: ctx->ring_pages);
350	ctx->ring_pages = NULL;
351	}
352	}
353
354	static int aio_ring_mremap(struct vm_area_struct *vma)
355	{
356	struct file *file = vma->vm_file;
357	struct mm_struct *mm = vma->vm_mm;
358	struct kioctx_table *table;
359	int i, res = -EINVAL;
360
361	spin_lock(lock: &mm->ioctx_lock);
362	rcu_read_lock();
363	table = rcu_dereference(mm->ioctx_table);
364	if (!table)
365	goto out_unlock;
366
367	for (i = 0; i < table->nr; i++) {
368	struct kioctx *ctx;
369
370	ctx = rcu_dereference(table->table[i]);
371	if (ctx && ctx->aio_ring_file == file) {
372	if (!atomic_read(v: &ctx->dead)) {
373	ctx->user_id = ctx->mmap_base = vma->vm_start;
374	res = 0;
375	}
376	break;
377	}
378	}
379
380	out_unlock:
381	rcu_read_unlock();
382	spin_unlock(lock: &mm->ioctx_lock);
383	return res;
384	}
385
386	static const struct vm_operations_struct aio_ring_vm_ops = {
387	.mremap = aio_ring_mremap,
388	#if IS_ENABLED(CONFIG_MMU)
389	.fault = filemap_fault,
390	.map_pages = filemap_map_pages,
391	.page_mkwrite = filemap_page_mkwrite,
392	#endif
393	};
394
395	static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
396	{
397	vm_flags_set(vma, VM_DONTEXPAND);
398	vma->vm_ops = &aio_ring_vm_ops;
399	return 0;
400	}
401
402	static const struct file_operations aio_ring_fops = {
403	.mmap = aio_ring_mmap,
404	};
405
406	#if IS_ENABLED(CONFIG_MIGRATION)
407	static int aio_migrate_folio(struct address_space *mapping, struct folio *dst,
408	struct folio *src, enum migrate_mode mode)
409	{
410	struct kioctx *ctx;
411	unsigned long flags;
412	pgoff_t idx;
413	int rc;
414
415	/*
416	* We cannot support the _NO_COPY case here, because copy needs to
417	* happen under the ctx->completion_lock. That does not work with the
418	* migration workflow of MIGRATE_SYNC_NO_COPY.
419	*/
420	if (mode == MIGRATE_SYNC_NO_COPY)
421	return -EINVAL;
422
423	rc = 0;
424
425	/* mapping->private_lock here protects against the kioctx teardown. */
426	spin_lock(lock: &mapping->private_lock);
427	ctx = mapping->private_data;
428	if (!ctx) {
429	rc = -EINVAL;
430	goto out;
431	}
432
433	/* The ring_lock mutex. The prevents aio_read_events() from writing
434	* to the ring's head, and prevents page migration from mucking in
435	* a partially initialized kiotx.
436	*/
437	if (!mutex_trylock(lock: &ctx->ring_lock)) {
438	rc = -EAGAIN;
439	goto out;
440	}
441
442	idx = src->index;
443	if (idx < (pgoff_t)ctx->nr_pages) {
444	/* Make sure the old folio hasn't already been changed */
445	if (ctx->ring_pages[idx] != &src->page)
446	rc = -EAGAIN;
447	} else
448	rc = -EINVAL;
449
450	if (rc != 0)
451	goto out_unlock;
452
453	/* Writeback must be complete */
454	BUG_ON(folio_test_writeback(src));
455	folio_get(folio: dst);
456
457	rc = folio_migrate_mapping(mapping, newfolio: dst, folio: src, extra_count: 1);
458	if (rc != MIGRATEPAGE_SUCCESS) {
459	folio_put(folio: dst);
460	goto out_unlock;
461	}
462
463	/* Take completion_lock to prevent other writes to the ring buffer
464	* while the old folio is copied to the new. This prevents new
465	* events from being lost.
466	*/
467	spin_lock_irqsave(&ctx->completion_lock, flags);
468	folio_migrate_copy(newfolio: dst, folio: src);
469	BUG_ON(ctx->ring_pages[idx] != &src->page);
470	ctx->ring_pages[idx] = &dst->page;
471	spin_unlock_irqrestore(lock: &ctx->completion_lock, flags);
472
473	/* The old folio is no longer accessible. */
474	folio_put(folio: src);
475
476	out_unlock:
477	mutex_unlock(lock: &ctx->ring_lock);
478	out:
479	spin_unlock(lock: &mapping->private_lock);
480	return rc;
481	}
482	#else
483	#define aio_migrate_folio NULL
484	#endif
485
486	static const struct address_space_operations aio_ctx_aops = {
487	.dirty_folio = noop_dirty_folio,
488	.migrate_folio = aio_migrate_folio,
489	};
490
491	static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
492	{
493	struct aio_ring *ring;
494	struct mm_struct *mm = current->mm;
495	unsigned long size, unused;
496	int nr_pages;
497	int i;
498	struct file *file;
499
500	/* Compensate for the ring buffer's head/tail overlap entry */
501	nr_events += 2; /* 1 is required, 2 for good luck */
502
503	size = sizeof(struct aio_ring);
504	size += sizeof(struct io_event) * nr_events;
505
506	nr_pages = PFN_UP(size);
507	if (nr_pages < 0)
508	return -EINVAL;
509
510	file = aio_private_file(ctx, nr_pages);
511	if (IS_ERR(ptr: file)) {
512	ctx->aio_ring_file = NULL;
513	return -ENOMEM;
514	}
515
516	ctx->aio_ring_file = file;
517	nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
518	/ sizeof(struct io_event);
519
520	ctx->ring_pages = ctx->internal_pages;
521	if (nr_pages > AIO_RING_PAGES) {
522	ctx->ring_pages = kcalloc(n: nr_pages, size: sizeof(struct page *),
523	GFP_KERNEL);
524	if (!ctx->ring_pages) {
525	put_aio_ring_file(ctx);
526	return -ENOMEM;
527	}
528	}
529
530	for (i = 0; i < nr_pages; i++) {
531	struct page *page;
532	page = find_or_create_page(mapping: file->f_mapping,
533	index: i, GFP_USER | __GFP_ZERO);
534	if (!page)
535	break;
536	pr_debug("pid(%d) page[%d]->count=%d\n",
537	current->pid, i, page_count(page));
538	SetPageUptodate(page);
539	unlock_page(page);
540
541	ctx->ring_pages[i] = page;
542	}
543	ctx->nr_pages = i;
544
545	if (unlikely(i != nr_pages)) {
546	aio_free_ring(ctx);
547	return -ENOMEM;
548	}
549
550	ctx->mmap_size = nr_pages * PAGE_SIZE;
551	pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
552
553	if (mmap_write_lock_killable(mm)) {
554	ctx->mmap_size = 0;
555	aio_free_ring(ctx);
556	return -EINTR;
557	}
558
559	ctx->mmap_base = do_mmap(file: ctx->aio_ring_file, addr: 0, len: ctx->mmap_size,
560	PROT_READ | PROT_WRITE,
561	MAP_SHARED, vm_flags: 0, pgoff: 0, populate: &unused, NULL);
562	mmap_write_unlock(mm);
563	if (IS_ERR(ptr: (void *)ctx->mmap_base)) {
564	ctx->mmap_size = 0;
565	aio_free_ring(ctx);
566	return -ENOMEM;
567	}
568
569	pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
570
571	ctx->user_id = ctx->mmap_base;
572	ctx->nr_events = nr_events; /* trusted copy */
573
574	ring = page_address(ctx->ring_pages[0]);
575	ring->nr = nr_events; /* user copy */
576	ring->id = ~0U;
577	ring->head = ring->tail = 0;
578	ring->magic = AIO_RING_MAGIC;
579	ring->compat_features = AIO_RING_COMPAT_FEATURES;
580	ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
581	ring->header_length = sizeof(struct aio_ring);
582	flush_dcache_page(page: ctx->ring_pages[0]);
583
584	return 0;
585	}
586
587	#define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
588	#define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
589	#define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
590
591	void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
592	{
593	struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, rw);
594	struct kioctx *ctx = req->ki_ctx;
595	unsigned long flags;
596
597	if (WARN_ON_ONCE(!list_empty(&req->ki_list)))
598	return;
599
600	spin_lock_irqsave(&ctx->ctx_lock, flags);
601	list_add_tail(new: &req->ki_list, head: &ctx->active_reqs);
602	req->ki_cancel = cancel;
603	spin_unlock_irqrestore(lock: &ctx->ctx_lock, flags);
604	}
605	EXPORT_SYMBOL(kiocb_set_cancel_fn);
606
607	/*
608	* free_ioctx() should be RCU delayed to synchronize against the RCU
609	* protected lookup_ioctx() and also needs process context to call
610	* aio_free_ring(). Use rcu_work.
611	*/
612	static void free_ioctx(struct work_struct *work)
613	{
614	struct kioctx *ctx = container_of(to_rcu_work(work), struct kioctx,
615	free_rwork);
616	pr_debug("freeing %p\n", ctx);
617
618	aio_free_ring(ctx);
619	free_percpu(pdata: ctx->cpu);
620	percpu_ref_exit(ref: &ctx->reqs);
621	percpu_ref_exit(ref: &ctx->users);
622	kmem_cache_free(s: kioctx_cachep, objp: ctx);
623	}
624
625	static void free_ioctx_reqs(struct percpu_ref *ref)
626	{
627	struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
628
629	/* At this point we know that there are no any in-flight requests */
630	if (ctx->rq_wait && atomic_dec_and_test(v: &ctx->rq_wait->count))
631	complete(&ctx->rq_wait->comp);
632
633	/* Synchronize against RCU protected table->table[] dereferences */
634	INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
635	queue_rcu_work(wq: system_wq, rwork: &ctx->free_rwork);
636	}
637
638	/*
639	* When this function runs, the kioctx has been removed from the "hash table"
640	* and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
641	* now it's safe to cancel any that need to be.
642	*/
643	static void free_ioctx_users(struct percpu_ref *ref)
644	{
645	struct kioctx *ctx = container_of(ref, struct kioctx, users);
646	struct aio_kiocb *req;
647
648	spin_lock_irq(lock: &ctx->ctx_lock);
649
650	while (!list_empty(head: &ctx->active_reqs)) {
651	req = list_first_entry(&ctx->active_reqs,
652	struct aio_kiocb, ki_list);
653	req->ki_cancel(&req->rw);
654	list_del_init(entry: &req->ki_list);
655	}
656
657	spin_unlock_irq(lock: &ctx->ctx_lock);
658
659	percpu_ref_kill(ref: &ctx->reqs);
660	percpu_ref_put(ref: &ctx->reqs);
661	}
662
663	static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
664	{
665	unsigned i, new_nr;
666	struct kioctx_table *table, *old;
667	struct aio_ring *ring;
668
669	spin_lock(lock: &mm->ioctx_lock);
670	table = rcu_dereference_raw(mm->ioctx_table);
671
672	while (1) {
673	if (table)
674	for (i = 0; i < table->nr; i++)
675	if (!rcu_access_pointer(table->table[i])) {
676	ctx->id = i;
677	rcu_assign_pointer(table->table[i], ctx);
678	spin_unlock(lock: &mm->ioctx_lock);
679
680	/* While kioctx setup is in progress,
681	* we are protected from page migration
682	* changes ring_pages by ->ring_lock.
683	*/
684	ring = page_address(ctx->ring_pages[0]);
685	ring->id = ctx->id;
686	return 0;
687	}
688
689	new_nr = (table ? table->nr : 1) * 4;
690	spin_unlock(lock: &mm->ioctx_lock);
691
692	table = kzalloc(struct_size(table, table, new_nr), GFP_KERNEL);
693	if (!table)
694	return -ENOMEM;
695
696	table->nr = new_nr;
697
698	spin_lock(lock: &mm->ioctx_lock);
699	old = rcu_dereference_raw(mm->ioctx_table);
700
701	if (!old) {
702	rcu_assign_pointer(mm->ioctx_table, table);
703	} else if (table->nr > old->nr) {
704	memcpy(table->table, old->table,
705	old->nr * sizeof(struct kioctx *));
706
707	rcu_assign_pointer(mm->ioctx_table, table);
708	kfree_rcu(old, rcu);
709	} else {
710	kfree(objp: table);
711	table = old;
712	}
713	}
714	}
715
716	static void aio_nr_sub(unsigned nr)
717	{
718	spin_lock(lock: &aio_nr_lock);
719	if (WARN_ON(aio_nr - nr > aio_nr))
720	aio_nr = 0;
721	else
722	aio_nr -= nr;
723	spin_unlock(lock: &aio_nr_lock);
724	}
725
726	/* ioctx_alloc
727	* Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
728	*/
729	static struct kioctx *ioctx_alloc(unsigned nr_events)
730	{
731	struct mm_struct *mm = current->mm;
732	struct kioctx *ctx;
733	int err = -ENOMEM;
734
735	/*
736	* Store the original nr_events -- what userspace passed to io_setup(),
737	* for counting against the global limit -- before it changes.
738	*/
739	unsigned int max_reqs = nr_events;
740
741	/*
742	* We keep track of the number of available ringbuffer slots, to prevent
743	* overflow (reqs_available), and we also use percpu counters for this.
744	*
745	* So since up to half the slots might be on other cpu's percpu counters
746	* and unavailable, double nr_events so userspace sees what they
747	* expected: additionally, we move req_batch slots to/from percpu
748	* counters at a time, so make sure that isn't 0:
749	*/
750	nr_events = max(nr_events, num_possible_cpus() * 4);
751	nr_events *= 2;
752
753	/* Prevent overflows */
754	if (nr_events > (0x10000000U / sizeof(struct io_event))) {
755	pr_debug("ENOMEM: nr_events too high\n");
756	return ERR_PTR(error: -EINVAL);
757	}
758
759	if (!nr_events || (unsigned long)max_reqs > aio_max_nr)
760	return ERR_PTR(error: -EAGAIN);
761
762	ctx = kmem_cache_zalloc(k: kioctx_cachep, GFP_KERNEL);
763	if (!ctx)
764	return ERR_PTR(error: -ENOMEM);
765
766	ctx->max_reqs = max_reqs;
767
768	spin_lock_init(&ctx->ctx_lock);
769	spin_lock_init(&ctx->completion_lock);
770	mutex_init(&ctx->ring_lock);
771	/* Protect against page migration throughout kiotx setup by keeping
772	* the ring_lock mutex held until setup is complete. */
773	mutex_lock(&ctx->ring_lock);
774	init_waitqueue_head(&ctx->wait);
775
776	INIT_LIST_HEAD(list: &ctx->active_reqs);
777
778	if (percpu_ref_init(ref: &ctx->users, release: free_ioctx_users, flags: 0, GFP_KERNEL))
779	goto err;
780
781	if (percpu_ref_init(ref: &ctx->reqs, release: free_ioctx_reqs, flags: 0, GFP_KERNEL))
782	goto err;
783
784	ctx->cpu = alloc_percpu(struct kioctx_cpu);
785	if (!ctx->cpu)
786	goto err;
787
788	err = aio_setup_ring(ctx, nr_events);
789	if (err < 0)
790	goto err;
791
792	atomic_set(v: &ctx->reqs_available, i: ctx->nr_events - 1);
793	ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
794	if (ctx->req_batch < 1)
795	ctx->req_batch = 1;
796
797	/* limit the number of system wide aios */
798	spin_lock(lock: &aio_nr_lock);
799	if (aio_nr + ctx->max_reqs > aio_max_nr ||
800	aio_nr + ctx->max_reqs < aio_nr) {
801	spin_unlock(lock: &aio_nr_lock);
802	err = -EAGAIN;
803	goto err_ctx;
804	}
805	aio_nr += ctx->max_reqs;
806	spin_unlock(lock: &aio_nr_lock);
807
808	percpu_ref_get(ref: &ctx->users); /* io_setup() will drop this ref */
809	percpu_ref_get(ref: &ctx->reqs); /* free_ioctx_users() will drop this */
810
811	err = ioctx_add_table(ctx, mm);
812	if (err)
813	goto err_cleanup;
814
815	/* Release the ring_lock mutex now that all setup is complete. */
816	mutex_unlock(lock: &ctx->ring_lock);
817
818	pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
819	ctx, ctx->user_id, mm, ctx->nr_events);
820	return ctx;
821
822	err_cleanup:
823	aio_nr_sub(nr: ctx->max_reqs);
824	err_ctx:
825	atomic_set(v: &ctx->dead, i: 1);
826	if (ctx->mmap_size)
827	vm_munmap(ctx->mmap_base, ctx->mmap_size);
828	aio_free_ring(ctx);
829	err:
830	mutex_unlock(lock: &ctx->ring_lock);
831	free_percpu(pdata: ctx->cpu);
832	percpu_ref_exit(ref: &ctx->reqs);
833	percpu_ref_exit(ref: &ctx->users);
834	kmem_cache_free(s: kioctx_cachep, objp: ctx);
835	pr_debug("error allocating ioctx %d\n", err);
836	return ERR_PTR(error: err);
837	}
838
839	/* kill_ioctx
840	* Cancels all outstanding aio requests on an aio context. Used
841	* when the processes owning a context have all exited to encourage
842	* the rapid destruction of the kioctx.
843	*/
844	static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
845	struct ctx_rq_wait *wait)
846	{
847	struct kioctx_table *table;
848
849	spin_lock(lock: &mm->ioctx_lock);
850	if (atomic_xchg(v: &ctx->dead, new: 1)) {
851	spin_unlock(lock: &mm->ioctx_lock);
852	return -EINVAL;
853	}
854
855	table = rcu_dereference_raw(mm->ioctx_table);
856	WARN_ON(ctx != rcu_access_pointer(table->table[ctx->id]));
857	RCU_INIT_POINTER(table->table[ctx->id], NULL);
858	spin_unlock(lock: &mm->ioctx_lock);
859
860	/* free_ioctx_reqs() will do the necessary RCU synchronization */
861	wake_up_all(&ctx->wait);
862
863	/*
864	* It'd be more correct to do this in free_ioctx(), after all
865	* the outstanding kiocbs have finished - but by then io_destroy
866	* has already returned, so io_setup() could potentially return
867	* -EAGAIN with no ioctxs actually in use (as far as userspace
868	* could tell).
869	*/
870	aio_nr_sub(nr: ctx->max_reqs);
871
872	if (ctx->mmap_size)
873	vm_munmap(ctx->mmap_base, ctx->mmap_size);
874
875	ctx->rq_wait = wait;
876	percpu_ref_kill(ref: &ctx->users);
877	return 0;
878	}
879
880	/*
881	* exit_aio: called when the last user of mm goes away. At this point, there is
882	* no way for any new requests to be submited or any of the io_* syscalls to be
883	* called on the context.
884	*
885	* There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
886	* them.
887	*/
888	void exit_aio(struct mm_struct *mm)
889	{
890	struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
891	struct ctx_rq_wait wait;
892	int i, skipped;
893
894	if (!table)
895	return;
896
897	atomic_set(v: &wait.count, i: table->nr);
898	init_completion(x: &wait.comp);
899
900	skipped = 0;
901	for (i = 0; i < table->nr; ++i) {
902	struct kioctx *ctx =
903	rcu_dereference_protected(table->table[i], true);
904
905	if (!ctx) {
906	skipped++;
907	continue;
908	}
909
910	/*
911	* We don't need to bother with munmap() here - exit_mmap(mm)
912	* is coming and it'll unmap everything. And we simply can't,
913	* this is not necessarily our ->mm.
914	* Since kill_ioctx() uses non-zero ->mmap_size as indicator
915	* that it needs to unmap the area, just set it to 0.
916	*/
917	ctx->mmap_size = 0;
918	kill_ioctx(mm, ctx, wait: &wait);
919	}
920
921	if (!atomic_sub_and_test(i: skipped, v: &wait.count)) {
922	/* Wait until all IO for the context are done. */
923	wait_for_completion(&wait.comp);
924	}
925
926	RCU_INIT_POINTER(mm->ioctx_table, NULL);
927	kfree(objp: table);
928	}
929
930	static void put_reqs_available(struct kioctx *ctx, unsigned nr)
931	{
932	struct kioctx_cpu *kcpu;
933	unsigned long flags;
934
935	local_irq_save(flags);
936	kcpu = this_cpu_ptr(ctx->cpu);
937	kcpu->reqs_available += nr;
938
939	while (kcpu->reqs_available >= ctx->req_batch * 2) {
940	kcpu->reqs_available -= ctx->req_batch;
941	atomic_add(i: ctx->req_batch, v: &ctx->reqs_available);
942	}
943
944	local_irq_restore(flags);
945	}
946
947	static bool __get_reqs_available(struct kioctx *ctx)
948	{
949	struct kioctx_cpu *kcpu;
950	bool ret = false;
951	unsigned long flags;
952
953	local_irq_save(flags);
954	kcpu = this_cpu_ptr(ctx->cpu);
955	if (!kcpu->reqs_available) {
956	int avail = atomic_read(v: &ctx->reqs_available);
957
958	do {
959	if (avail < ctx->req_batch)
960	goto out;
961	} while (!atomic_try_cmpxchg(v: &ctx->reqs_available,
962	old: &avail, new: avail - ctx->req_batch));
963
964	kcpu->reqs_available += ctx->req_batch;
965	}
966
967	ret = true;
968	kcpu->reqs_available--;
969	out:
970	local_irq_restore(flags);
971	return ret;
972	}
973
974	/* refill_reqs_available
975	* Updates the reqs_available reference counts used for tracking the
976	* number of free slots in the completion ring. This can be called
977	* from aio_complete() (to optimistically update reqs_available) or
978	* from aio_get_req() (the we're out of events case). It must be
979	* called holding ctx->completion_lock.
980	*/
981	static void refill_reqs_available(struct kioctx *ctx, unsigned head,
982	unsigned tail)
983	{
984	unsigned events_in_ring, completed;
985
986	/* Clamp head since userland can write to it. */
987	head %= ctx->nr_events;
988	if (head <= tail)
989	events_in_ring = tail - head;
990	else
991	events_in_ring = ctx->nr_events - (head - tail);
992
993	completed = ctx->completed_events;
994	if (events_in_ring < completed)
995	completed -= events_in_ring;
996	else
997	completed = 0;
998
999	if (!completed)
1000	return;
1001
1002	ctx->completed_events -= completed;
1003	put_reqs_available(ctx, nr: completed);
1004	}
1005
1006	/* user_refill_reqs_available
1007	* Called to refill reqs_available when aio_get_req() encounters an
1008	* out of space in the completion ring.
1009	*/
1010	static void user_refill_reqs_available(struct kioctx *ctx)
1011	{
1012	spin_lock_irq(lock: &ctx->completion_lock);
1013	if (ctx->completed_events) {
1014	struct aio_ring *ring;
1015	unsigned head;
1016
1017	/* Access of ring->head may race with aio_read_events_ring()
1018	* here, but that's okay since whether we read the old version
1019	* or the new version, and either will be valid. The important
1020	* part is that head cannot pass tail since we prevent
1021	* aio_complete() from updating tail by holding
1022	* ctx->completion_lock. Even if head is invalid, the check
1023	* against ctx->completed_events below will make sure we do the
1024	* safe/right thing.
1025	*/
1026	ring = page_address(ctx->ring_pages[0]);
1027	head = ring->head;
1028
1029	refill_reqs_available(ctx, head, tail: ctx->tail);
1030	}
1031
1032	spin_unlock_irq(lock: &ctx->completion_lock);
1033	}
1034
1035	static bool get_reqs_available(struct kioctx *ctx)
1036	{
1037	if (__get_reqs_available(ctx))
1038	return true;
1039	user_refill_reqs_available(ctx);
1040	return __get_reqs_available(ctx);
1041	}
1042
1043	/* aio_get_req
1044	* Allocate a slot for an aio request.
1045	* Returns NULL if no requests are free.
1046	*
1047	* The refcount is initialized to 2 - one for the async op completion,
1048	* one for the synchronous code that does this.
1049	*/
1050	static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
1051	{
1052	struct aio_kiocb *req;
1053
1054	req = kmem_cache_alloc(cachep: kiocb_cachep, GFP_KERNEL);
1055	if (unlikely(!req))
1056	return NULL;
1057
1058	if (unlikely(!get_reqs_available(ctx))) {
1059	kmem_cache_free(s: kiocb_cachep, objp: req);
1060	return NULL;
1061	}
1062
1063	percpu_ref_get(ref: &ctx->reqs);
1064	req->ki_ctx = ctx;
1065	INIT_LIST_HEAD(list: &req->ki_list);
1066	refcount_set(r: &req->ki_refcnt, n: 2);
1067	req->ki_eventfd = NULL;
1068	return req;
1069	}
1070
1071	static struct kioctx *lookup_ioctx(unsigned long ctx_id)
1072	{
1073	struct aio_ring __user *ring = (void __user *)ctx_id;
1074	struct mm_struct *mm = current->mm;
1075	struct kioctx *ctx, *ret = NULL;
1076	struct kioctx_table *table;
1077	unsigned id;
1078
1079	if (get_user(id, &ring->id))
1080	return NULL;
1081
1082	rcu_read_lock();
1083	table = rcu_dereference(mm->ioctx_table);
1084
1085	if (!table || id >= table->nr)
1086	goto out;
1087
1088	id = array_index_nospec(id, table->nr);
1089	ctx = rcu_dereference(table->table[id]);
1090	if (ctx && ctx->user_id == ctx_id) {
1091	if (percpu_ref_tryget_live(ref: &ctx->users))
1092	ret = ctx;
1093	}
1094	out:
1095	rcu_read_unlock();
1096	return ret;
1097	}
1098
1099	static inline void iocb_destroy(struct aio_kiocb *iocb)
1100	{
1101	if (iocb->ki_eventfd)
1102	eventfd_ctx_put(ctx: iocb->ki_eventfd);
1103	if (iocb->ki_filp)
1104	fput(iocb->ki_filp);
1105	percpu_ref_put(ref: &iocb->ki_ctx->reqs);
1106	kmem_cache_free(s: kiocb_cachep, objp: iocb);
1107	}
1108
1109	/* aio_complete
1110	* Called when the io request on the given iocb is complete.
1111	*/
1112	static void aio_complete(struct aio_kiocb *iocb)
1113	{
1114	struct kioctx *ctx = iocb->ki_ctx;
1115	struct aio_ring *ring;
1116	struct io_event *ev_page, *event;
1117	unsigned tail, pos, head;
1118	unsigned long flags;
1119
1120	/*
1121	* Add a completion event to the ring buffer. Must be done holding
1122	* ctx->completion_lock to prevent other code from messing with the tail
1123	* pointer since we might be called from irq context.
1124	*/
1125	spin_lock_irqsave(&ctx->completion_lock, flags);
1126
1127	tail = ctx->tail;
1128	pos = tail + AIO_EVENTS_OFFSET;
1129
1130	if (++tail >= ctx->nr_events)
1131	tail = 0;
1132
1133	ev_page = page_address(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1134	event = ev_page + pos % AIO_EVENTS_PER_PAGE;
1135
1136	*event = iocb->ki_res;
1137
1138	flush_dcache_page(page: ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1139
1140	pr_debug("%p[%u]: %p: %p %Lx %Lx %Lx\n", ctx, tail, iocb,
1141	(void __user *)(unsigned long)iocb->ki_res.obj,
1142	iocb->ki_res.data, iocb->ki_res.res, iocb->ki_res.res2);
1143
1144	/* after flagging the request as done, we
1145	* must never even look at it again
1146	*/
1147	smp_wmb(); /* make event visible before updating tail */
1148
1149	ctx->tail = tail;
1150
1151	ring = page_address(ctx->ring_pages[0]);
1152	head = ring->head;
1153	ring->tail = tail;
1154	flush_dcache_page(page: ctx->ring_pages[0]);
1155
1156	ctx->completed_events++;
1157	if (ctx->completed_events > 1)
1158	refill_reqs_available(ctx, head, tail);
1159	spin_unlock_irqrestore(lock: &ctx->completion_lock, flags);
1160
1161	pr_debug("added to ring %p at [%u]\n", iocb, tail);
1162
1163	/*
1164	* Check if the user asked us to deliver the result through an
1165	* eventfd. The eventfd_signal() function is safe to be called
1166	* from IRQ context.
1167	*/
1168	if (iocb->ki_eventfd)
1169	eventfd_signal(ctx: iocb->ki_eventfd, n: 1);
1170
1171	/*
1172	* We have to order our ring_info tail store above and test
1173	* of the wait list below outside the wait lock. This is
1174	* like in wake_up_bit() where clearing a bit has to be
1175	* ordered with the unlocked test.
1176	*/
1177	smp_mb();
1178
1179	if (waitqueue_active(wq_head: &ctx->wait))
1180	wake_up(&ctx->wait);
1181	}
1182
1183	static inline void iocb_put(struct aio_kiocb *iocb)
1184	{
1185	if (refcount_dec_and_test(r: &iocb->ki_refcnt)) {
1186	aio_complete(iocb);
1187	iocb_destroy(iocb);
1188	}
1189	}
1190
1191	/* aio_read_events_ring
1192	* Pull an event off of the ioctx's event ring. Returns the number of
1193	* events fetched
1194	*/
1195	static long aio_read_events_ring(struct kioctx *ctx,
1196	struct io_event __user *event, long nr)
1197	{
1198	struct aio_ring *ring;
1199	unsigned head, tail, pos;
1200	long ret = 0;
1201	int copy_ret;
1202
1203	/*
1204	* The mutex can block and wake us up and that will cause
1205	* wait_event_interruptible_hrtimeout() to schedule without sleeping
1206	* and repeat. This should be rare enough that it doesn't cause
1207	* peformance issues. See the comment in read_events() for more detail.
1208	*/
1209	sched_annotate_sleep();
1210	mutex_lock(&ctx->ring_lock);
1211
1212	/* Access to ->ring_pages here is protected by ctx->ring_lock. */
1213	ring = page_address(ctx->ring_pages[0]);
1214	head = ring->head;
1215	tail = ring->tail;
1216
1217	/*
1218	* Ensure that once we've read the current tail pointer, that
1219	* we also see the events that were stored up to the tail.
1220	*/
1221	smp_rmb();
1222
1223	pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
1224
1225	if (head == tail)
1226	goto out;
1227
1228	head %= ctx->nr_events;
1229	tail %= ctx->nr_events;
1230
1231	while (ret < nr) {
1232	long avail;
1233	struct io_event *ev;
1234	struct page *page;
1235
1236	avail = (head <= tail ? tail : ctx->nr_events) - head;
1237	if (head == tail)
1238	break;
1239
1240	pos = head + AIO_EVENTS_OFFSET;
1241	page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
1242	pos %= AIO_EVENTS_PER_PAGE;
1243
1244	avail = min(avail, nr - ret);
1245	avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
1246
1247	ev = page_address(page);
1248	copy_ret = copy_to_user(to: event + ret, from: ev + pos,
1249	n: sizeof(*ev) * avail);
1250
1251	if (unlikely(copy_ret)) {
1252	ret = -EFAULT;
1253	goto out;
1254	}
1255
1256	ret += avail;
1257	head += avail;
1258	head %= ctx->nr_events;
1259	}
1260
1261	ring = page_address(ctx->ring_pages[0]);
1262	ring->head = head;
1263	flush_dcache_page(page: ctx->ring_pages[0]);
1264
1265	pr_debug("%li h%u t%u\n", ret, head, tail);
1266	out:
1267	mutex_unlock(lock: &ctx->ring_lock);
1268
1269	return ret;
1270	}
1271
1272	static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
1273	struct io_event __user *event, long *i)
1274	{
1275	long ret = aio_read_events_ring(ctx, event: event + *i, nr: nr - *i);
1276
1277	if (ret > 0)
1278	*i += ret;
1279
1280	if (unlikely(atomic_read(&ctx->dead)))
1281	ret = -EINVAL;
1282
1283	if (!*i)
1284	*i = ret;
1285
1286	return ret < 0 || *i >= min_nr;
1287	}
1288
1289	static long read_events(struct kioctx *ctx, long min_nr, long nr,
1290	struct io_event __user *event,
1291	ktime_t until)
1292	{
1293	long ret = 0;
1294
1295	/*
1296	* Note that aio_read_events() is being called as the conditional - i.e.
1297	* we're calling it after prepare_to_wait() has set task state to
1298	* TASK_INTERRUPTIBLE.
1299	*
1300	* But aio_read_events() can block, and if it blocks it's going to flip
1301	* the task state back to TASK_RUNNING.
1302	*
1303	* This should be ok, provided it doesn't flip the state back to
1304	* TASK_RUNNING and return 0 too much - that causes us to spin. That
1305	* will only happen if the mutex_lock() call blocks, and we then find
1306	* the ringbuffer empty. So in practice we should be ok, but it's
1307	* something to be aware of when touching this code.
1308	*/
1309	if (until == 0)
1310	aio_read_events(ctx, min_nr, nr, event, i: &ret);
1311	else
1312	wait_event_interruptible_hrtimeout(ctx->wait,
1313	aio_read_events(ctx, min_nr, nr, event, &ret),
1314	until);
1315	return ret;
1316	}
1317
1318	/* sys_io_setup:
1319	* Create an aio_context capable of receiving at least nr_events.
1320	* ctxp must not point to an aio_context that already exists, and
1321	* must be initialized to 0 prior to the call. On successful
1322	* creation of the aio_context, *ctxp is filled in with the resulting
1323	* handle. May fail with -EINVAL if *ctxp is not initialized,
1324	* if the specified nr_events exceeds internal limits. May fail
1325	* with -EAGAIN if the specified nr_events exceeds the user's limit
1326	* of available events. May fail with -ENOMEM if insufficient kernel
1327	* resources are available. May fail with -EFAULT if an invalid
1328	* pointer is passed for ctxp. Will fail with -ENOSYS if not
1329	* implemented.
1330	*/
1331	SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1332	{
1333	struct kioctx *ioctx = NULL;
1334	unsigned long ctx;
1335	long ret;
1336
1337	ret = get_user(ctx, ctxp);
1338	if (unlikely(ret))
1339	goto out;
1340
1341	ret = -EINVAL;
1342	if (unlikely(ctx || nr_events == 0)) {
1343	pr_debug("EINVAL: ctx %lu nr_events %u\n",
1344	ctx, nr_events);
1345	goto out;
1346	}
1347
1348	ioctx = ioctx_alloc(nr_events);
1349	ret = PTR_ERR(ptr: ioctx);
1350	if (!IS_ERR(ptr: ioctx)) {
1351	ret = put_user(ioctx->user_id, ctxp);
1352	if (ret)
1353	kill_ioctx(current->mm, ctx: ioctx, NULL);
1354	percpu_ref_put(ref: &ioctx->users);
1355	}
1356
1357	out:
1358	return ret;
1359	}
1360
1361	#ifdef CONFIG_COMPAT
1362	COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
1363	{
1364	struct kioctx *ioctx = NULL;
1365	unsigned long ctx;
1366	long ret;
1367
1368	ret = get_user(ctx, ctx32p);
1369	if (unlikely(ret))
1370	goto out;
1371
1372	ret = -EINVAL;
1373	if (unlikely(ctx || nr_events == 0)) {
1374	pr_debug("EINVAL: ctx %lu nr_events %u\n",
1375	ctx, nr_events);
1376	goto out;
1377	}
1378
1379	ioctx = ioctx_alloc(nr_events);
1380	ret = PTR_ERR(ptr: ioctx);
1381	if (!IS_ERR(ptr: ioctx)) {
1382	/* truncating is ok because it's a user address */
1383	ret = put_user((u32)ioctx->user_id, ctx32p);
1384	if (ret)
1385	kill_ioctx(current->mm, ctx: ioctx, NULL);
1386	percpu_ref_put(ref: &ioctx->users);
1387	}
1388
1389	out:
1390	return ret;
1391	}
1392	#endif
1393
1394	/* sys_io_destroy:
1395	* Destroy the aio_context specified. May cancel any outstanding
1396	* AIOs and block on completion. Will fail with -ENOSYS if not
1397	* implemented. May fail with -EINVAL if the context pointed to
1398	* is invalid.
1399	*/
1400	SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1401	{
1402	struct kioctx *ioctx = lookup_ioctx(ctx_id: ctx);
1403	if (likely(NULL != ioctx)) {
1404	struct ctx_rq_wait wait;
1405	int ret;
1406
1407	init_completion(x: &wait.comp);
1408	atomic_set(v: &wait.count, i: 1);
1409
1410	/* Pass requests_done to kill_ioctx() where it can be set
1411	* in a thread-safe way. If we try to set it here then we have
1412	* a race condition if two io_destroy() called simultaneously.
1413	*/
1414	ret = kill_ioctx(current->mm, ctx: ioctx, wait: &wait);
1415	percpu_ref_put(ref: &ioctx->users);
1416
1417	/* Wait until all IO for the context are done. Otherwise kernel
1418	* keep using user-space buffers even if user thinks the context
1419	* is destroyed.
1420	*/
1421	if (!ret)
1422	wait_for_completion(&wait.comp);
1423
1424	return ret;
1425	}
1426	pr_debug("EINVAL: invalid context id\n");
1427	return -EINVAL;
1428	}
1429
1430	static void aio_remove_iocb(struct aio_kiocb *iocb)
1431	{
1432	struct kioctx *ctx = iocb->ki_ctx;
1433	unsigned long flags;
1434
1435	spin_lock_irqsave(&ctx->ctx_lock, flags);
1436	list_del(entry: &iocb->ki_list);
1437	spin_unlock_irqrestore(lock: &ctx->ctx_lock, flags);
1438	}
1439
1440	static void aio_complete_rw(struct kiocb *kiocb, long res)
1441	{
1442	struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, rw);
1443
1444	if (!list_empty_careful(head: &iocb->ki_list))
1445	aio_remove_iocb(iocb);
1446
1447	if (kiocb->ki_flags & IOCB_WRITE) {
1448	struct inode *inode = file_inode(f: kiocb->ki_filp);
1449
1450	if (S_ISREG(inode->i_mode))
1451	kiocb_end_write(iocb: kiocb);
1452	}
1453
1454	iocb->ki_res.res = res;
1455	iocb->ki_res.res2 = 0;
1456	iocb_put(iocb);
1457	}
1458
1459	static int aio_prep_rw(struct kiocb *req, const struct iocb *iocb)
1460	{
1461	int ret;
1462
1463	req->ki_complete = aio_complete_rw;
1464	req->private = NULL;
1465	req->ki_pos = iocb->aio_offset;
1466	req->ki_flags = req->ki_filp->f_iocb_flags;
1467	if (iocb->aio_flags & IOCB_FLAG_RESFD)
1468	req->ki_flags |= IOCB_EVENTFD;
1469	if (iocb->aio_flags & IOCB_FLAG_IOPRIO) {
1470	/*
1471	* If the IOCB_FLAG_IOPRIO flag of aio_flags is set, then
1472	* aio_reqprio is interpreted as an I/O scheduling
1473	* class and priority.
1474	*/
1475	ret = ioprio_check_cap(ioprio: iocb->aio_reqprio);
1476	if (ret) {
1477	pr_debug("aio ioprio check cap error: %d\n", ret);
1478	return ret;
1479	}
1480
1481	req->ki_ioprio = iocb->aio_reqprio;
1482	} else
1483	req->ki_ioprio = get_current_ioprio();
1484
1485	ret = kiocb_set_rw_flags(ki: req, flags: iocb->aio_rw_flags);
1486	if (unlikely(ret))
1487	return ret;
1488
1489	req->ki_flags &= ~IOCB_HIPRI; /* no one is going to poll for this I/O */
1490	return 0;
1491	}
1492
1493	static ssize_t aio_setup_rw(int rw, const struct iocb *iocb,
1494	struct iovec **iovec, bool vectored, bool compat,
1495	struct iov_iter *iter)
1496	{
1497	void __user *buf = (void __user *)(uintptr_t)iocb->aio_buf;
1498	size_t len = iocb->aio_nbytes;
1499
1500	if (!vectored) {
1501	ssize_t ret = import_single_range(type: rw, buf, len, iov: *iovec, i: iter);
1502	*iovec = NULL;
1503	return ret;
1504	}
1505
1506	return __import_iovec(type: rw, uvec: buf, nr_segs: len, UIO_FASTIOV, iovp: iovec, i: iter, compat);
1507	}
1508
1509	static inline void aio_rw_done(struct kiocb *req, ssize_t ret)
1510	{
1511	switch (ret) {
1512	case -EIOCBQUEUED:
1513	break;
1514	case -ERESTARTSYS:
1515	case -ERESTARTNOINTR:
1516	case -ERESTARTNOHAND:
1517	case -ERESTART_RESTARTBLOCK:
1518	/*
1519	* There's no easy way to restart the syscall since other AIO's
1520	* may be already running. Just fail this IO with EINTR.
1521	*/
1522	ret = -EINTR;
1523	fallthrough;
1524	default:
1525	req->ki_complete(req, ret);
1526	}
1527	}
1528
1529	static int aio_read(struct kiocb *req, const struct iocb *iocb,
1530	bool vectored, bool compat)
1531	{
1532	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1533	struct iov_iter iter;
1534	struct file *file;
1535	int ret;
1536
1537	ret = aio_prep_rw(req, iocb);
1538	if (ret)
1539	return ret;
1540	file = req->ki_filp;
1541	if (unlikely(!(file->f_mode & FMODE_READ)))
1542	return -EBADF;
1543	if (unlikely(!file->f_op->read_iter))
1544	return -EINVAL;
1545
1546	ret = aio_setup_rw(ITER_DEST, iocb, iovec: &iovec, vectored, compat, iter: &iter);
1547	if (ret < 0)
1548	return ret;
1549	ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(i: &iter));
1550	if (!ret)
1551	aio_rw_done(req, ret: call_read_iter(file, kio: req, iter: &iter));
1552	kfree(objp: iovec);
1553	return ret;
1554	}
1555
1556	static int aio_write(struct kiocb *req, const struct iocb *iocb,
1557	bool vectored, bool compat)
1558	{
1559	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1560	struct iov_iter iter;
1561	struct file *file;
1562	int ret;
1563
1564	ret = aio_prep_rw(req, iocb);
1565	if (ret)
1566	return ret;
1567	file = req->ki_filp;
1568
1569	if (unlikely(!(file->f_mode & FMODE_WRITE)))
1570	return -EBADF;
1571	if (unlikely(!file->f_op->write_iter))
1572	return -EINVAL;
1573
1574	ret = aio_setup_rw(ITER_SOURCE, iocb, iovec: &iovec, vectored, compat, iter: &iter);
1575	if (ret < 0)
1576	return ret;
1577	ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(i: &iter));
1578	if (!ret) {
1579	if (S_ISREG(file_inode(file)->i_mode))
1580	kiocb_start_write(iocb: req);
1581	req->ki_flags |= IOCB_WRITE;
1582	aio_rw_done(req, ret: call_write_iter(file, kio: req, iter: &iter));
1583	}
1584	kfree(objp: iovec);
1585	return ret;
1586	}
1587
1588	static void aio_fsync_work(struct work_struct *work)
1589	{
1590	struct aio_kiocb *iocb = container_of(work, struct aio_kiocb, fsync.work);
1591	const struct cred *old_cred = override_creds(iocb->fsync.creds);
1592
1593	iocb->ki_res.res = vfs_fsync(file: iocb->fsync.file, datasync: iocb->fsync.datasync);
1594	revert_creds(old_cred);
1595	put_cred(cred: iocb->fsync.creds);
1596	iocb_put(iocb);
1597	}
1598
1599	static int aio_fsync(struct fsync_iocb *req, const struct iocb *iocb,
1600	bool datasync)
1601	{
1602	if (unlikely(iocb->aio_buf || iocb->aio_offset || iocb->aio_nbytes ||
1603	iocb->aio_rw_flags))
1604	return -EINVAL;
1605
1606	if (unlikely(!req->file->f_op->fsync))
1607	return -EINVAL;
1608
1609	req->creds = prepare_creds();
1610	if (!req->creds)
1611	return -ENOMEM;
1612
1613	req->datasync = datasync;
1614	INIT_WORK(&req->work, aio_fsync_work);
1615	schedule_work(work: &req->work);
1616	return 0;
1617	}
1618
1619	static void aio_poll_put_work(struct work_struct *work)
1620	{
1621	struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1622	struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1623
1624	iocb_put(iocb);
1625	}
1626
1627	/*
1628	* Safely lock the waitqueue which the request is on, synchronizing with the
1629	* case where the ->poll() provider decides to free its waitqueue early.
1630	*
1631	* Returns true on success, meaning that req->head->lock was locked, req->wait
1632	* is on req->head, and an RCU read lock was taken. Returns false if the
1633	* request was already removed from its waitqueue (which might no longer exist).
1634	*/
1635	static bool poll_iocb_lock_wq(struct poll_iocb *req)
1636	{
1637	wait_queue_head_t *head;
1638
1639	/*
1640	* While we hold the waitqueue lock and the waitqueue is nonempty,
1641	* wake_up_pollfree() will wait for us. However, taking the waitqueue
1642	* lock in the first place can race with the waitqueue being freed.
1643	*
1644	* We solve this as eventpoll does: by taking advantage of the fact that
1645	* all users of wake_up_pollfree() will RCU-delay the actual free. If
1646	* we enter rcu_read_lock() and see that the pointer to the queue is
1647	* non-NULL, we can then lock it without the memory being freed out from
1648	* under us, then check whether the request is still on the queue.
1649	*
1650	* Keep holding rcu_read_lock() as long as we hold the queue lock, in
1651	* case the caller deletes the entry from the queue, leaving it empty.
1652	* In that case, only RCU prevents the queue memory from being freed.
1653	*/
1654	rcu_read_lock();
1655	head = smp_load_acquire(&req->head);
1656	if (head) {
1657	spin_lock(lock: &head->lock);
1658	if (!list_empty(head: &req->wait.entry))
1659	return true;
1660	spin_unlock(lock: &head->lock);
1661	}
1662	rcu_read_unlock();
1663	return false;
1664	}
1665
1666	static void poll_iocb_unlock_wq(struct poll_iocb *req)
1667	{
1668	spin_unlock(lock: &req->head->lock);
1669	rcu_read_unlock();
1670	}
1671
1672	static void aio_poll_complete_work(struct work_struct *work)
1673	{
1674	struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1675	struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1676	struct poll_table_struct pt = { ._key = req->events };
1677	struct kioctx *ctx = iocb->ki_ctx;
1678	__poll_t mask = 0;
1679
1680	if (!READ_ONCE(req->cancelled))
1681	mask = vfs_poll(file: req->file, pt: &pt) & req->events;
1682
1683	/*
1684	* Note that ->ki_cancel callers also delete iocb from active_reqs after
1685	* calling ->ki_cancel. We need the ctx_lock roundtrip here to
1686	* synchronize with them. In the cancellation case the list_del_init
1687	* itself is not actually needed, but harmless so we keep it in to
1688	* avoid further branches in the fast path.
1689	*/
1690	spin_lock_irq(lock: &ctx->ctx_lock);
1691	if (poll_iocb_lock_wq(req)) {
1692	if (!mask && !READ_ONCE(req->cancelled)) {
1693	/*
1694	* The request isn't actually ready to be completed yet.
1695	* Reschedule completion if another wakeup came in.
1696	*/
1697	if (req->work_need_resched) {
1698	schedule_work(work: &req->work);
1699	req->work_need_resched = false;
1700	} else {
1701	req->work_scheduled = false;
1702	}
1703	poll_iocb_unlock_wq(req);
1704	spin_unlock_irq(lock: &ctx->ctx_lock);
1705	return;
1706	}
1707	list_del_init(entry: &req->wait.entry);
1708	poll_iocb_unlock_wq(req);
1709	} /* else, POLLFREE has freed the waitqueue, so we must complete */
1710	list_del_init(entry: &iocb->ki_list);
1711	iocb->ki_res.res = mangle_poll(val: mask);
1712	spin_unlock_irq(lock: &ctx->ctx_lock);
1713
1714	iocb_put(iocb);
1715	}
1716
1717	/* assumes we are called with irqs disabled */
1718	static int aio_poll_cancel(struct kiocb *iocb)
1719	{
1720	struct aio_kiocb *aiocb = container_of(iocb, struct aio_kiocb, rw);
1721	struct poll_iocb *req = &aiocb->poll;
1722
1723	if (poll_iocb_lock_wq(req)) {
1724	WRITE_ONCE(req->cancelled, true);
1725	if (!req->work_scheduled) {
1726	schedule_work(work: &aiocb->poll.work);
1727	req->work_scheduled = true;
1728	}
1729	poll_iocb_unlock_wq(req);
1730	} /* else, the request was force-cancelled by POLLFREE already */
1731
1732	return 0;
1733	}
1734
1735	static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
1736	void *key)
1737	{
1738	struct poll_iocb *req = container_of(wait, struct poll_iocb, wait);
1739	struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1740	__poll_t mask = key_to_poll(key);
1741	unsigned long flags;
1742
1743	/* for instances that support it check for an event match first: */
1744	if (mask && !(mask & req->events))
1745	return 0;
1746
1747	/*
1748	* Complete the request inline if possible. This requires that three
1749	* conditions be met:
1750	* 1. An event mask must have been passed. If a plain wakeup was done
1751	* instead, then mask == 0 and we have to call vfs_poll() to get
1752	* the events, so inline completion isn't possible.
1753	* 2. The completion work must not have already been scheduled.
1754	* 3. ctx_lock must not be busy. We have to use trylock because we
1755	* already hold the waitqueue lock, so this inverts the normal
1756	* locking order. Use irqsave/irqrestore because not all
1757	* filesystems (e.g. fuse) call this function with IRQs disabled,
1758	* yet IRQs have to be disabled before ctx_lock is obtained.
1759	*/
1760	if (mask && !req->work_scheduled &&
1761	spin_trylock_irqsave(&iocb->ki_ctx->ctx_lock, flags)) {
1762	struct kioctx *ctx = iocb->ki_ctx;
1763
1764	list_del_init(entry: &req->wait.entry);
1765	list_del(entry: &iocb->ki_list);
1766	iocb->ki_res.res = mangle_poll(val: mask);
1767	if (iocb->ki_eventfd && !eventfd_signal_allowed()) {
1768	iocb = NULL;
1769	INIT_WORK(&req->work, aio_poll_put_work);
1770	schedule_work(work: &req->work);
1771	}
1772	spin_unlock_irqrestore(lock: &ctx->ctx_lock, flags);
1773	if (iocb)
1774	iocb_put(iocb);
1775	} else {
1776	/*
1777	* Schedule the completion work if needed. If it was already
1778	* scheduled, record that another wakeup came in.
1779	*
1780	* Don't remove the request from the waitqueue here, as it might
1781	* not actually be complete yet (we won't know until vfs_poll()
1782	* is called), and we must not miss any wakeups. POLLFREE is an
1783	* exception to this; see below.
1784	*/
1785	if (req->work_scheduled) {
1786	req->work_need_resched = true;
1787	} else {
1788	schedule_work(work: &req->work);
1789	req->work_scheduled = true;
1790	}
1791
1792	/*
1793	* If the waitqueue is being freed early but we can't complete
1794	* the request inline, we have to tear down the request as best
1795	* we can. That means immediately removing the request from its
1796	* waitqueue and preventing all further accesses to the
1797	* waitqueue via the request. We also need to schedule the
1798	* completion work (done above). Also mark the request as
1799	* cancelled, to potentially skip an unneeded call to ->poll().
1800	*/
1801	if (mask & POLLFREE) {
1802	WRITE_ONCE(req->cancelled, true);
1803	list_del_init(entry: &req->wait.entry);
1804
1805	/*
1806	* Careful: this *must* be the last step, since as soon
1807	* as req->head is NULL'ed out, the request can be
1808	* completed and freed, since aio_poll_complete_work()
1809	* will no longer need to take the waitqueue lock.
1810	*/
1811	smp_store_release(&req->head, NULL);
1812	}
1813	}
1814	return 1;
1815	}
1816
1817	struct aio_poll_table {
1818	struct poll_table_struct pt;
1819	struct aio_kiocb *iocb;
1820	bool queued;
1821	int error;
1822	};
1823
1824	static void
1825	aio_poll_queue_proc(struct file *file, struct wait_queue_head *head,
1826	struct poll_table_struct *p)
1827	{
1828	struct aio_poll_table *pt = container_of(p, struct aio_poll_table, pt);
1829
1830	/* multiple wait queues per file are not supported */
1831	if (unlikely(pt->queued)) {
1832	pt->error = -EINVAL;
1833	return;
1834	}
1835
1836	pt->queued = true;
1837	pt->error = 0;
1838	pt->iocb->poll.head = head;
1839	add_wait_queue(wq_head: head, wq_entry: &pt->iocb->poll.wait);
1840	}
1841
1842	static int aio_poll(struct aio_kiocb *aiocb, const struct iocb *iocb)
1843	{
1844	struct kioctx *ctx = aiocb->ki_ctx;
1845	struct poll_iocb *req = &aiocb->poll;
1846	struct aio_poll_table apt;
1847	bool cancel = false;
1848	__poll_t mask;
1849
1850	/* reject any unknown events outside the normal event mask. */
1851	if ((u16)iocb->aio_buf != iocb->aio_buf)
1852	return -EINVAL;
1853	/* reject fields that are not defined for poll */
1854	if (iocb->aio_offset || iocb->aio_nbytes || iocb->aio_rw_flags)
1855	return -EINVAL;
1856
1857	INIT_WORK(&req->work, aio_poll_complete_work);
1858	req->events = demangle_poll(val: iocb->aio_buf) | EPOLLERR | EPOLLHUP;
1859
1860	req->head = NULL;
1861	req->cancelled = false;
1862	req->work_scheduled = false;
1863	req->work_need_resched = false;
1864
1865	apt.pt._qproc = aio_poll_queue_proc;
1866	apt.pt._key = req->events;
1867	apt.iocb = aiocb;
1868	apt.queued = false;
1869	apt.error = -EINVAL; /* same as no support for IOCB_CMD_POLL */
1870
1871	/* initialized the list so that we can do list_empty checks */
1872	INIT_LIST_HEAD(list: &req->wait.entry);
1873	init_waitqueue_func_entry(wq_entry: &req->wait, func: aio_poll_wake);
1874
1875	mask = vfs_poll(file: req->file, pt: &apt.pt) & req->events;
1876	spin_lock_irq(lock: &ctx->ctx_lock);
1877	if (likely(apt.queued)) {
1878	bool on_queue = poll_iocb_lock_wq(req);
1879
1880	if (!on_queue || req->work_scheduled) {
1881	/*
1882	* aio_poll_wake() already either scheduled the async
1883	* completion work, or completed the request inline.
1884	*/
1885	if (apt.error) /* unsupported case: multiple queues */
1886	cancel = true;
1887	apt.error = 0;
1888	mask = 0;
1889	}
1890	if (mask || apt.error) {
1891	/* Steal to complete synchronously. */
1892	list_del_init(entry: &req->wait.entry);
1893	} else if (cancel) {
1894	/* Cancel if possible (may be too late though). */
1895	WRITE_ONCE(req->cancelled, true);
1896	} else if (on_queue) {
1897	/*
1898	* Actually waiting for an event, so add the request to
1899	* active_reqs so that it can be cancelled if needed.
1900	*/
1901	list_add_tail(new: &aiocb->ki_list, head: &ctx->active_reqs);
1902	aiocb->ki_cancel = aio_poll_cancel;
1903	}
1904	if (on_queue)
1905	poll_iocb_unlock_wq(req);
1906	}
1907	if (mask) { /* no async, we'd stolen it */
1908	aiocb->ki_res.res = mangle_poll(val: mask);
1909	apt.error = 0;
1910	}
1911	spin_unlock_irq(lock: &ctx->ctx_lock);
1912	if (mask)
1913	iocb_put(iocb: aiocb);
1914	return apt.error;
1915	}
1916
1917	static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
1918	struct iocb __user *user_iocb, struct aio_kiocb *req,
1919	bool compat)
1920	{
1921	req->ki_filp = fget(fd: iocb->aio_fildes);
1922	if (unlikely(!req->ki_filp))
1923	return -EBADF;
1924
1925	if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1926	struct eventfd_ctx *eventfd;
1927	/*
1928	* If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1929	* instance of the file* now. The file descriptor must be
1930	* an eventfd() fd, and will be signaled for each completed
1931	* event using the eventfd_signal() function.
1932	*/
1933	eventfd = eventfd_ctx_fdget(fd: iocb->aio_resfd);
1934	if (IS_ERR(ptr: eventfd))
1935	return PTR_ERR(ptr: eventfd);
1936
1937	req->ki_eventfd = eventfd;
1938	}
1939
1940	if (unlikely(put_user(KIOCB_KEY, &user_iocb->aio_key))) {
1941	pr_debug("EFAULT: aio_key\n");
1942	return -EFAULT;
1943	}
1944
1945	req->ki_res.obj = (u64)(unsigned long)user_iocb;
1946	req->ki_res.data = iocb->aio_data;
1947	req->ki_res.res = 0;
1948	req->ki_res.res2 = 0;
1949
1950	switch (iocb->aio_lio_opcode) {
1951	case IOCB_CMD_PREAD:
1952	return aio_read(req: &req->rw, iocb, vectored: false, compat);
1953	case IOCB_CMD_PWRITE:
1954	return aio_write(req: &req->rw, iocb, vectored: false, compat);
1955	case IOCB_CMD_PREADV:
1956	return aio_read(req: &req->rw, iocb, vectored: true, compat);
1957	case IOCB_CMD_PWRITEV:
1958	return aio_write(req: &req->rw, iocb, vectored: true, compat);
1959	case IOCB_CMD_FSYNC:
1960	return aio_fsync(req: &req->fsync, iocb, datasync: false);
1961	case IOCB_CMD_FDSYNC:
1962	return aio_fsync(req: &req->fsync, iocb, datasync: true);
1963	case IOCB_CMD_POLL:
1964	return aio_poll(aiocb: req, iocb);
1965	default:
1966	pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
1967	return -EINVAL;
1968	}
1969	}
1970
1971	static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1972	bool compat)
1973	{
1974	struct aio_kiocb *req;
1975	struct iocb iocb;
1976	int err;
1977
1978	if (unlikely(copy_from_user(&iocb, user_iocb, sizeof(iocb))))
1979	return -EFAULT;
1980
1981	/* enforce forwards compatibility on users */
1982	if (unlikely(iocb.aio_reserved2)) {
1983	pr_debug("EINVAL: reserve field set\n");
1984	return -EINVAL;
1985	}
1986
1987	/* prevent overflows */
1988	if (unlikely(
1989	(iocb.aio_buf != (unsigned long)iocb.aio_buf) ||
1990	(iocb.aio_nbytes != (size_t)iocb.aio_nbytes) ||
1991	((ssize_t)iocb.aio_nbytes < 0)
1992	)) {
1993	pr_debug("EINVAL: overflow check\n");
1994	return -EINVAL;
1995	}
1996
1997	req = aio_get_req(ctx);
1998	if (unlikely(!req))
1999	return -EAGAIN;
2000
2001	err = __io_submit_one(ctx, iocb: &iocb, user_iocb, req, compat);
2002
2003	/* Done with the synchronous reference */
2004	iocb_put(iocb: req);
2005
2006	/*
2007	* If err is 0, we'd either done aio_complete() ourselves or have
2008	* arranged for that to be done asynchronously. Anything non-zero
2009	* means that we need to destroy req ourselves.
2010	*/
2011	if (unlikely(err)) {
2012	iocb_destroy(iocb: req);
2013	put_reqs_available(ctx, nr: 1);
2014	}
2015	return err;
2016	}
2017
2018	/* sys_io_submit:
2019	* Queue the nr iocbs pointed to by iocbpp for processing. Returns
2020	* the number of iocbs queued. May return -EINVAL if the aio_context
2021	* specified by ctx_id is invalid, if nr is < 0, if the iocb at
2022	* *iocbpp[0] is not properly initialized, if the operation specified
2023	* is invalid for the file descriptor in the iocb. May fail with
2024	* -EFAULT if any of the data structures point to invalid data. May
2025	* fail with -EBADF if the file descriptor specified in the first
2026	* iocb is invalid. May fail with -EAGAIN if insufficient resources
2027	* are available to queue any iocbs. Will return 0 if nr is 0. Will
2028	* fail with -ENOSYS if not implemented.
2029	*/
2030	SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
2031	struct iocb __user * __user *, iocbpp)
2032	{
2033	struct kioctx *ctx;
2034	long ret = 0;
2035	int i = 0;
2036	struct blk_plug plug;
2037
2038	if (unlikely(nr < 0))
2039	return -EINVAL;
2040
2041	ctx = lookup_ioctx(ctx_id);
2042	if (unlikely(!ctx)) {
2043	pr_debug("EINVAL: invalid context id\n");
2044	return -EINVAL;
2045	}
2046
2047	if (nr > ctx->nr_events)
2048	nr = ctx->nr_events;
2049
2050	if (nr > AIO_PLUG_THRESHOLD)
2051	blk_start_plug(&plug);
2052	for (i = 0; i < nr; i++) {
2053	struct iocb __user *user_iocb;
2054
2055	if (unlikely(get_user(user_iocb, iocbpp + i))) {
2056	ret = -EFAULT;
2057	break;
2058	}
2059
2060	ret = io_submit_one(ctx, user_iocb, compat: false);
2061	if (ret)
2062	break;
2063	}
2064	if (nr > AIO_PLUG_THRESHOLD)
2065	blk_finish_plug(&plug);
2066
2067	percpu_ref_put(ref: &ctx->users);
2068	return i ? i : ret;
2069	}
2070
2071	#ifdef CONFIG_COMPAT
2072	COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
2073	int, nr, compat_uptr_t __user *, iocbpp)
2074	{
2075	struct kioctx *ctx;
2076	long ret = 0;
2077	int i = 0;
2078	struct blk_plug plug;
2079
2080	if (unlikely(nr < 0))
2081	return -EINVAL;
2082
2083	ctx = lookup_ioctx(ctx_id);
2084	if (unlikely(!ctx)) {
2085	pr_debug("EINVAL: invalid context id\n");
2086	return -EINVAL;
2087	}
2088
2089	if (nr > ctx->nr_events)
2090	nr = ctx->nr_events;
2091
2092	if (nr > AIO_PLUG_THRESHOLD)
2093	blk_start_plug(&plug);
2094	for (i = 0; i < nr; i++) {
2095	compat_uptr_t user_iocb;
2096
2097	if (unlikely(get_user(user_iocb, iocbpp + i))) {
2098	ret = -EFAULT;
2099	break;
2100	}
2101
2102	ret = io_submit_one(ctx, user_iocb: compat_ptr(uptr: user_iocb), compat: true);
2103	if (ret)
2104	break;
2105	}
2106	if (nr > AIO_PLUG_THRESHOLD)
2107	blk_finish_plug(&plug);
2108
2109	percpu_ref_put(ref: &ctx->users);
2110	return i ? i : ret;
2111	}
2112	#endif
2113
2114	/* sys_io_cancel:
2115	* Attempts to cancel an iocb previously passed to io_submit. If
2116	* the operation is successfully cancelled, the resulting event is
2117	* copied into the memory pointed to by result without being placed
2118	* into the completion queue and 0 is returned. May fail with
2119	* -EFAULT if any of the data structures pointed to are invalid.
2120	* May fail with -EINVAL if aio_context specified by ctx_id is
2121	* invalid. May fail with -EAGAIN if the iocb specified was not
2122	* cancelled. Will fail with -ENOSYS if not implemented.
2123	*/
2124	SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
2125	struct io_event __user *, result)
2126	{
2127	struct kioctx *ctx;
2128	struct aio_kiocb *kiocb;
2129	int ret = -EINVAL;
2130	u32 key;
2131	u64 obj = (u64)(unsigned long)iocb;
2132
2133	if (unlikely(get_user(key, &iocb->aio_key)))
2134	return -EFAULT;
2135	if (unlikely(key != KIOCB_KEY))
2136	return -EINVAL;
2137
2138	ctx = lookup_ioctx(ctx_id);
2139	if (unlikely(!ctx))
2140	return -EINVAL;
2141
2142	spin_lock_irq(lock: &ctx->ctx_lock);
2143	/* TODO: use a hash or array, this sucks. */
2144	list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
2145	if (kiocb->ki_res.obj == obj) {
2146	ret = kiocb->ki_cancel(&kiocb->rw);
2147	list_del_init(entry: &kiocb->ki_list);
2148	break;
2149	}
2150	}
2151	spin_unlock_irq(lock: &ctx->ctx_lock);
2152
2153	if (!ret) {
2154	/*
2155	* The result argument is no longer used - the io_event is
2156	* always delivered via the ring buffer. -EINPROGRESS indicates
2157	* cancellation is progress:
2158	*/
2159	ret = -EINPROGRESS;
2160	}
2161
2162	percpu_ref_put(ref: &ctx->users);
2163
2164	return ret;
2165	}
2166
2167	static long do_io_getevents(aio_context_t ctx_id,
2168	long min_nr,
2169	long nr,
2170	struct io_event __user *events,
2171	struct timespec64 *ts)
2172	{
2173	ktime_t until = ts ? timespec64_to_ktime(ts: *ts) : KTIME_MAX;
2174	struct kioctx *ioctx = lookup_ioctx(ctx_id);
2175	long ret = -EINVAL;
2176
2177	if (likely(ioctx)) {
2178	if (likely(min_nr <= nr && min_nr >= 0))
2179	ret = read_events(ctx: ioctx, min_nr, nr, event: events, until);
2180	percpu_ref_put(ref: &ioctx->users);
2181	}
2182
2183	return ret;
2184	}
2185
2186	/* io_getevents:
2187	* Attempts to read at least min_nr events and up to nr events from
2188	* the completion queue for the aio_context specified by ctx_id. If
2189	* it succeeds, the number of read events is returned. May fail with
2190	* -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
2191	* out of range, if timeout is out of range. May fail with -EFAULT
2192	* if any of the memory specified is invalid. May return 0 or
2193	* < min_nr if the timeout specified by timeout has elapsed
2194	* before sufficient events are available, where timeout == NULL
2195	* specifies an infinite timeout. Note that the timeout pointed to by
2196	* timeout is relative. Will fail with -ENOSYS if not implemented.
2197	*/
2198	#ifdef CONFIG_64BIT
2199
2200	SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
2201	long, min_nr,
2202	long, nr,
2203	struct io_event __user *, events,
2204	struct __kernel_timespec __user *, timeout)
2205	{
2206	struct timespec64 ts;
2207	int ret;
2208
2209	if (timeout && unlikely(get_timespec64(&ts, timeout)))
2210	return -EFAULT;
2211
2212	ret = do_io_getevents(ctx_id, min_nr, nr, events, ts: timeout ? &ts : NULL);
2213	if (!ret && signal_pending(current))
2214	ret = -EINTR;
2215	return ret;
2216	}
2217
2218	#endif
2219
2220	struct __aio_sigset {
2221	const sigset_t __user *sigmask;
2222	size_t sigsetsize;
2223	};
2224
2225	SYSCALL_DEFINE6(io_pgetevents,
2226	aio_context_t, ctx_id,
2227	long, min_nr,
2228	long, nr,
2229	struct io_event __user *, events,
2230	struct __kernel_timespec __user *, timeout,
2231	const struct __aio_sigset __user *, usig)
2232	{
2233	struct __aio_sigset ksig = { NULL, };
2234	struct timespec64 ts;
2235	bool interrupted;
2236	int ret;
2237
2238	if (timeout && unlikely(get_timespec64(&ts, timeout)))
2239	return -EFAULT;
2240
2241	if (usig && copy_from_user(to: &ksig, from: usig, n: sizeof(ksig)))
2242	return -EFAULT;
2243
2244	ret = set_user_sigmask(umask: ksig.sigmask, sigsetsize: ksig.sigsetsize);
2245	if (ret)
2246	return ret;
2247
2248	ret = do_io_getevents(ctx_id, min_nr, nr, events, ts: timeout ? &ts : NULL);
2249
2250	interrupted = signal_pending(current);
2251	restore_saved_sigmask_unless(interrupted);
2252	if (interrupted && !ret)
2253	ret = -ERESTARTNOHAND;
2254
2255	return ret;
2256	}
2257
2258	#if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)
2259
2260	SYSCALL_DEFINE6(io_pgetevents_time32,
2261	aio_context_t, ctx_id,
2262	long, min_nr,
2263	long, nr,
2264	struct io_event __user *, events,
2265	struct old_timespec32 __user *, timeout,
2266	const struct __aio_sigset __user *, usig)
2267	{
2268	struct __aio_sigset ksig = { NULL, };
2269	struct timespec64 ts;
2270	bool interrupted;
2271	int ret;
2272
2273	if (timeout && unlikely(get_old_timespec32(&ts, timeout)))
2274	return -EFAULT;
2275
2276	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2277	return -EFAULT;
2278
2279
2280	ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
2281	if (ret)
2282	return ret;
2283
2284	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2285
2286	interrupted = signal_pending(current);
2287	restore_saved_sigmask_unless(interrupted);
2288	if (interrupted && !ret)
2289	ret = -ERESTARTNOHAND;
2290
2291	return ret;
2292	}
2293
2294	#endif
2295
2296	#if defined(CONFIG_COMPAT_32BIT_TIME)
2297
2298	SYSCALL_DEFINE5(io_getevents_time32, __u32, ctx_id,
2299	__s32, min_nr,
2300	__s32, nr,
2301	struct io_event __user *, events,
2302	struct old_timespec32 __user *, timeout)
2303	{
2304	struct timespec64 t;
2305	int ret;
2306
2307	if (timeout && get_old_timespec32(&t, timeout))
2308	return -EFAULT;
2309
2310	ret = do_io_getevents(ctx_id, min_nr, nr, events, ts: timeout ? &t : NULL);
2311	if (!ret && signal_pending(current))
2312	ret = -EINTR;
2313	return ret;
2314	}
2315
2316	#endif
2317
2318	#ifdef CONFIG_COMPAT
2319
2320	struct __compat_aio_sigset {
2321	compat_uptr_t sigmask;
2322	compat_size_t sigsetsize;
2323	};
2324
2325	#if defined(CONFIG_COMPAT_32BIT_TIME)
2326
2327	COMPAT_SYSCALL_DEFINE6(io_pgetevents,
2328	compat_aio_context_t, ctx_id,
2329	compat_long_t, min_nr,
2330	compat_long_t, nr,
2331	struct io_event __user *, events,
2332	struct old_timespec32 __user *, timeout,
2333	const struct __compat_aio_sigset __user *, usig)
2334	{
2335	struct __compat_aio_sigset ksig = { 0, };
2336	struct timespec64 t;
2337	bool interrupted;
2338	int ret;
2339
2340	if (timeout && get_old_timespec32(&t, timeout))
2341	return -EFAULT;
2342
2343	if (usig && copy_from_user(to: &ksig, from: usig, n: sizeof(ksig)))
2344	return -EFAULT;
2345
2346	ret = set_compat_user_sigmask(umask: compat_ptr(uptr: ksig.sigmask), sigsetsize: ksig.sigsetsize);
2347	if (ret)
2348	return ret;
2349
2350	ret = do_io_getevents(ctx_id, min_nr, nr, events, ts: timeout ? &t : NULL);
2351
2352	interrupted = signal_pending(current);
2353	restore_saved_sigmask_unless(interrupted);
2354	if (interrupted && !ret)
2355	ret = -ERESTARTNOHAND;
2356
2357	return ret;
2358	}
2359
2360	#endif
2361
2362	COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64,
2363	compat_aio_context_t, ctx_id,
2364	compat_long_t, min_nr,
2365	compat_long_t, nr,
2366	struct io_event __user *, events,
2367	struct __kernel_timespec __user *, timeout,
2368	const struct __compat_aio_sigset __user *, usig)
2369	{
2370	struct __compat_aio_sigset ksig = { 0, };
2371	struct timespec64 t;
2372	bool interrupted;
2373	int ret;
2374
2375	if (timeout && get_timespec64(ts: &t, uts: timeout))
2376	return -EFAULT;
2377
2378	if (usig && copy_from_user(to: &ksig, from: usig, n: sizeof(ksig)))
2379	return -EFAULT;
2380
2381	ret = set_compat_user_sigmask(umask: compat_ptr(uptr: ksig.sigmask), sigsetsize: ksig.sigsetsize);
2382	if (ret)
2383	return ret;
2384
2385	ret = do_io_getevents(ctx_id, min_nr, nr, events, ts: timeout ? &t : NULL);
2386
2387	interrupted = signal_pending(current);
2388	restore_saved_sigmask_unless(interrupted);
2389	if (interrupted && !ret)
2390	ret = -ERESTARTNOHAND;
2391
2392	return ret;
2393	}
2394	#endif
2395