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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 *
9 * See ../COPYING for licensing terms.
10 */
11#define pr_fmt(fmt) "%s: " fmt, __func__
12
13#include <linux/kernel.h>
14#include <linux/init.h>
15#include <linux/errno.h>
16#include <linux/time.h>
17#include <linux/aio_abi.h>
18#include <linux/export.h>
19#include <linux/syscalls.h>
20#include <linux/backing-dev.h>
21#include <linux/uio.h>
22
23#include <linux/sched/signal.h>
24#include <linux/fs.h>
25#include <linux/file.h>
26#include <linux/mm.h>
27#include <linux/mman.h>
28#include <linux/mmu_context.h>
29#include <linux/percpu.h>
30#include <linux/slab.h>
31#include <linux/timer.h>
32#include <linux/aio.h>
33#include <linux/highmem.h>
34#include <linux/workqueue.h>
35#include <linux/security.h>
36#include <linux/eventfd.h>
37#include <linux/blkdev.h>
38#include <linux/compat.h>
39#include <linux/migrate.h>
40#include <linux/ramfs.h>
41#include <linux/percpu-refcount.h>
42#include <linux/mount.h>
43
44#include <asm/kmap_types.h>
45#include <linux/uaccess.h>
46
47#include "internal.h"
48
49#define AIO_RING_MAGIC 0xa10a10a1
50#define AIO_RING_COMPAT_FEATURES 1
51#define AIO_RING_INCOMPAT_FEATURES 0
52struct aio_ring {
53 unsigned id; /* kernel internal index number */
54 unsigned nr; /* number of io_events */
55 unsigned head; /* Written to by userland or under ring_lock
56 * mutex by aio_read_events_ring(). */
57 unsigned tail;
58
59 unsigned magic;
60 unsigned compat_features;
61 unsigned incompat_features;
62 unsigned header_length; /* size of aio_ring */
63
64
65 struct io_event io_events[0];
66}; /* 128 bytes + ring size */
67
68#define AIO_RING_PAGES 8
69
70struct kioctx_table {
71 struct rcu_head rcu;
72 unsigned nr;
73 struct kioctx __rcu *table[];
74};
75
76struct kioctx_cpu {
77 unsigned reqs_available;
78};
79
80struct ctx_rq_wait {
81 struct completion comp;
82 atomic_t count;
83};
84
85struct kioctx {
86 struct percpu_ref users;
87 atomic_t dead;
88
89 struct percpu_ref reqs;
90
91 unsigned long user_id;
92
93 struct __percpu kioctx_cpu *cpu;
94
95 /*
96 * For percpu reqs_available, number of slots we move to/from global
97 * counter at a time:
98 */
99 unsigned req_batch;
100 /*
101 * This is what userspace passed to io_setup(), it's not used for
102 * anything but counting against the global max_reqs quota.
103 *
104 * The real limit is nr_events - 1, which will be larger (see
105 * aio_setup_ring())
106 */
107 unsigned max_reqs;
108
109 /* Size of ringbuffer, in units of struct io_event */
110 unsigned nr_events;
111
112 unsigned long mmap_base;
113 unsigned long mmap_size;
114
115 struct page **ring_pages;
116 long nr_pages;
117
118 struct rcu_work free_rwork; /* see free_ioctx() */
119
120 /*
121 * signals when all in-flight requests are done
122 */
123 struct ctx_rq_wait *rq_wait;
124
125 struct {
126 /*
127 * This counts the number of available slots in the ringbuffer,
128 * so we avoid overflowing it: it's decremented (if positive)
129 * when allocating a kiocb and incremented when the resulting
130 * io_event is pulled off the ringbuffer.
131 *
132 * We batch accesses to it with a percpu version.
133 */
134 atomic_t reqs_available;
135 } ____cacheline_aligned_in_smp;
136
137 struct {
138 spinlock_t ctx_lock;
139 struct list_head active_reqs; /* used for cancellation */
140 } ____cacheline_aligned_in_smp;
141
142 struct {
143 struct mutex ring_lock;
144 wait_queue_head_t wait;
145 } ____cacheline_aligned_in_smp;
146
147 struct {
148 unsigned tail;
149 unsigned completed_events;
150 spinlock_t completion_lock;
151 } ____cacheline_aligned_in_smp;
152
153 struct page *internal_pages[AIO_RING_PAGES];
154 struct file *aio_ring_file;
155
156 unsigned id;
157};
158
159/*
160 * We use ki_cancel == KIOCB_CANCELLED to indicate that a kiocb has been either
161 * cancelled or completed (this makes a certain amount of sense because
162 * successful cancellation - io_cancel() - does deliver the completion to
163 * userspace).
164 *
165 * And since most things don't implement kiocb cancellation and we'd really like
166 * kiocb completion to be lockless when possible, we use ki_cancel to
167 * synchronize cancellation and completion - we only set it to KIOCB_CANCELLED
168 * with xchg() or cmpxchg(), see batch_complete_aio() and kiocb_cancel().
169 */
170#define KIOCB_CANCELLED ((void *) (~0ULL))
171
172struct aio_kiocb {
173 struct kiocb common;
174
175 struct kioctx *ki_ctx;
176 kiocb_cancel_fn *ki_cancel;
177
178 struct iocb __user *ki_user_iocb; /* user's aiocb */
179 __u64 ki_user_data; /* user's data for completion */
180
181 struct list_head ki_list; /* the aio core uses this
182 * for cancellation */
183
184 /*
185 * If the aio_resfd field of the userspace iocb is not zero,
186 * this is the underlying eventfd context to deliver events to.
187 */
188 struct eventfd_ctx *ki_eventfd;
189};
190
191/*------ sysctl variables----*/
192static DEFINE_SPINLOCK(aio_nr_lock);
193unsigned long aio_nr; /* current system wide number of aio requests */
194unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
195/*----end sysctl variables---*/
196
197static struct kmem_cache *kiocb_cachep;
198static struct kmem_cache *kioctx_cachep;
199
200static struct vfsmount *aio_mnt;
201
202static const struct file_operations aio_ring_fops;
203static const struct address_space_operations aio_ctx_aops;
204
205static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
206{
207 struct qstr this = QSTR_INIT("[aio]", 5);
208 struct file *file;
209 struct path path;
210 struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
211 if (IS_ERR(inode))
212 return ERR_CAST(inode);
213
214 inode->i_mapping->a_ops = &aio_ctx_aops;
215 inode->i_mapping->private_data = ctx;
216 inode->i_size = PAGE_SIZE * nr_pages;
217
218 path.dentry = d_alloc_pseudo(aio_mnt->mnt_sb, &this);
219 if (!path.dentry) {
220 iput(inode);
221 return ERR_PTR(-ENOMEM);
222 }
223 path.mnt = mntget(aio_mnt);
224
225 d_instantiate(path.dentry, inode);
226 file = alloc_file(&path, FMODE_READ | FMODE_WRITE, &aio_ring_fops);
227 if (IS_ERR(file)) {
228 path_put(&path);
229 return file;
230 }
231
232 file->f_flags = O_RDWR;
233 return file;
234}
235
236static struct dentry *aio_mount(struct file_system_type *fs_type,
237 int flags, const char *dev_name, void *data)
238{
239 static const struct dentry_operations ops = {
240 .d_dname = simple_dname,
241 };
242 struct dentry *root = mount_pseudo(fs_type, "aio:", NULL, &ops,
243 AIO_RING_MAGIC);
244
245 if (!IS_ERR(root))
246 root->d_sb->s_iflags |= SB_I_NOEXEC;
247 return root;
248}
249
250/* aio_setup
251 * Creates the slab caches used by the aio routines, panic on
252 * failure as this is done early during the boot sequence.
253 */
254static int __init aio_setup(void)
255{
256 static struct file_system_type aio_fs = {
257 .name = "aio",
258 .mount = aio_mount,
259 .kill_sb = kill_anon_super,
260 };
261 aio_mnt = kern_mount(&aio_fs);
262 if (IS_ERR(aio_mnt))
263 panic("Failed to create aio fs mount.");
264
265 kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
266 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
267
268 pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
269
270 return 0;
271}
272__initcall(aio_setup);
273
274static void put_aio_ring_file(struct kioctx *ctx)
275{
276 struct file *aio_ring_file = ctx->aio_ring_file;
277 struct address_space *i_mapping;
278
279 if (aio_ring_file) {
280 truncate_setsize(file_inode(aio_ring_file), 0);
281
282 /* Prevent further access to the kioctx from migratepages */
283 i_mapping = aio_ring_file->f_mapping;
284 spin_lock(&i_mapping->private_lock);
285 i_mapping->private_data = NULL;
286 ctx->aio_ring_file = NULL;
287 spin_unlock(&i_mapping->private_lock);
288
289 fput(aio_ring_file);
290 }
291}
292
293static void aio_free_ring(struct kioctx *ctx)
294{
295 int i;
296
297 /* Disconnect the kiotx from the ring file. This prevents future
298 * accesses to the kioctx from page migration.
299 */
300 put_aio_ring_file(ctx);
301
302 for (i = 0; i < ctx->nr_pages; i++) {
303 struct page *page;
304 pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
305 page_count(ctx->ring_pages[i]));
306 page = ctx->ring_pages[i];
307 if (!page)
308 continue;
309 ctx->ring_pages[i] = NULL;
310 put_page(page);
311 }
312
313 if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
314 kfree(ctx->ring_pages);
315 ctx->ring_pages = NULL;
316 }
317}
318
319static int aio_ring_mremap(struct vm_area_struct *vma)
320{
321 struct file *file = vma->vm_file;
322 struct mm_struct *mm = vma->vm_mm;
323 struct kioctx_table *table;
324 int i, res = -EINVAL;
325
326 spin_lock(&mm->ioctx_lock);
327 rcu_read_lock();
328 table = rcu_dereference(mm->ioctx_table);
329 for (i = 0; i < table->nr; i++) {
330 struct kioctx *ctx;
331
332 ctx = rcu_dereference(table->table[i]);
333 if (ctx && ctx->aio_ring_file == file) {
334 if (!atomic_read(&ctx->dead)) {
335 ctx->user_id = ctx->mmap_base = vma->vm_start;
336 res = 0;
337 }
338 break;
339 }
340 }
341
342 rcu_read_unlock();
343 spin_unlock(&mm->ioctx_lock);
344 return res;
345}
346
347static const struct vm_operations_struct aio_ring_vm_ops = {
348 .mremap = aio_ring_mremap,
349#if IS_ENABLED(CONFIG_MMU)
350 .fault = filemap_fault,
351 .map_pages = filemap_map_pages,
352 .page_mkwrite = filemap_page_mkwrite,
353#endif
354};
355
356static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
357{
358 vma->vm_flags |= VM_DONTEXPAND;
359 vma->vm_ops = &aio_ring_vm_ops;
360 return 0;
361}
362
363static const struct file_operations aio_ring_fops = {
364 .mmap = aio_ring_mmap,
365};
366
367#if IS_ENABLED(CONFIG_MIGRATION)
368static int aio_migratepage(struct address_space *mapping, struct page *new,
369 struct page *old, enum migrate_mode mode)
370{
371 struct kioctx *ctx;
372 unsigned long flags;
373 pgoff_t idx;
374 int rc;
375
376 /*
377 * We cannot support the _NO_COPY case here, because copy needs to
378 * happen under the ctx->completion_lock. That does not work with the
379 * migration workflow of MIGRATE_SYNC_NO_COPY.
380 */
381 if (mode == MIGRATE_SYNC_NO_COPY)
382 return -EINVAL;
383
384 rc = 0;
385
386 /* mapping->private_lock here protects against the kioctx teardown. */
387 spin_lock(&mapping->private_lock);
388 ctx = mapping->private_data;
389 if (!ctx) {
390 rc = -EINVAL;
391 goto out;
392 }
393
394 /* The ring_lock mutex. The prevents aio_read_events() from writing
395 * to the ring's head, and prevents page migration from mucking in
396 * a partially initialized kiotx.
397 */
398 if (!mutex_trylock(&ctx->ring_lock)) {
399 rc = -EAGAIN;
400 goto out;
401 }
402
403 idx = old->index;
404 if (idx < (pgoff_t)ctx->nr_pages) {
405 /* Make sure the old page hasn't already been changed */
406 if (ctx->ring_pages[idx] != old)
407 rc = -EAGAIN;
408 } else
409 rc = -EINVAL;
410
411 if (rc != 0)
412 goto out_unlock;
413
414 /* Writeback must be complete */
415 BUG_ON(PageWriteback(old));
416 get_page(new);
417
418 rc = migrate_page_move_mapping(mapping, new, old, NULL, mode, 1);
419 if (rc != MIGRATEPAGE_SUCCESS) {
420 put_page(new);
421 goto out_unlock;
422 }
423
424 /* Take completion_lock to prevent other writes to the ring buffer
425 * while the old page is copied to the new. This prevents new
426 * events from being lost.
427 */
428 spin_lock_irqsave(&ctx->completion_lock, flags);
429 migrate_page_copy(new, old);
430 BUG_ON(ctx->ring_pages[idx] != old);
431 ctx->ring_pages[idx] = new;
432 spin_unlock_irqrestore(&ctx->completion_lock, flags);
433
434 /* The old page is no longer accessible. */
435 put_page(old);
436
437out_unlock:
438 mutex_unlock(&ctx->ring_lock);
439out:
440 spin_unlock(&mapping->private_lock);
441 return rc;
442}
443#endif
444
445static const struct address_space_operations aio_ctx_aops = {
446 .set_page_dirty = __set_page_dirty_no_writeback,
447#if IS_ENABLED(CONFIG_MIGRATION)
448 .migratepage = aio_migratepage,
449#endif
450};
451
452static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
453{
454 struct aio_ring *ring;
455 struct mm_struct *mm = current->mm;
456 unsigned long size, unused;
457 int nr_pages;
458 int i;
459 struct file *file;
460
461 /* Compensate for the ring buffer's head/tail overlap entry */
462 nr_events += 2; /* 1 is required, 2 for good luck */
463
464 size = sizeof(struct aio_ring);
465 size += sizeof(struct io_event) * nr_events;
466
467 nr_pages = PFN_UP(size);
468 if (nr_pages < 0)
469 return -EINVAL;
470
471 file = aio_private_file(ctx, nr_pages);
472 if (IS_ERR(file)) {
473 ctx->aio_ring_file = NULL;
474 return -ENOMEM;
475 }
476
477 ctx->aio_ring_file = file;
478 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
479 / sizeof(struct io_event);
480
481 ctx->ring_pages = ctx->internal_pages;
482 if (nr_pages > AIO_RING_PAGES) {
483 ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
484 GFP_KERNEL);
485 if (!ctx->ring_pages) {
486 put_aio_ring_file(ctx);
487 return -ENOMEM;
488 }
489 }
490
491 for (i = 0; i < nr_pages; i++) {
492 struct page *page;
493 page = find_or_create_page(file->f_mapping,
494 i, GFP_HIGHUSER | __GFP_ZERO);
495 if (!page)
496 break;
497 pr_debug("pid(%d) page[%d]->count=%d\n",
498 current->pid, i, page_count(page));
499 SetPageUptodate(page);
500 unlock_page(page);
501
502 ctx->ring_pages[i] = page;
503 }
504 ctx->nr_pages = i;
505
506 if (unlikely(i != nr_pages)) {
507 aio_free_ring(ctx);
508 return -ENOMEM;
509 }
510
511 ctx->mmap_size = nr_pages * PAGE_SIZE;
512 pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
513
514 if (down_write_killable(&mm->mmap_sem)) {
515 ctx->mmap_size = 0;
516 aio_free_ring(ctx);
517 return -EINTR;
518 }
519
520 ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size,
521 PROT_READ | PROT_WRITE,
522 MAP_SHARED, 0, &unused, NULL);
523 up_write(&mm->mmap_sem);
524 if (IS_ERR((void *)ctx->mmap_base)) {
525 ctx->mmap_size = 0;
526 aio_free_ring(ctx);
527 return -ENOMEM;
528 }
529
530 pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
531
532 ctx->user_id = ctx->mmap_base;
533 ctx->nr_events = nr_events; /* trusted copy */
534
535 ring = kmap_atomic(ctx->ring_pages[0]);
536 ring->nr = nr_events; /* user copy */
537 ring->id = ~0U;
538 ring->head = ring->tail = 0;
539 ring->magic = AIO_RING_MAGIC;
540 ring->compat_features = AIO_RING_COMPAT_FEATURES;
541 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
542 ring->header_length = sizeof(struct aio_ring);
543 kunmap_atomic(ring);
544 flush_dcache_page(ctx->ring_pages[0]);
545
546 return 0;
547}
548
549#define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
550#define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
551#define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
552
553void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
554{
555 struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, common);
556 struct kioctx *ctx = req->ki_ctx;
557 unsigned long flags;
558
559 spin_lock_irqsave(&ctx->ctx_lock, flags);
560
561 if (!req->ki_list.next)
562 list_add(&req->ki_list, &ctx->active_reqs);
563
564 req->ki_cancel = cancel;
565
566 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
567}
568EXPORT_SYMBOL(kiocb_set_cancel_fn);
569
570static int kiocb_cancel(struct aio_kiocb *kiocb)
571{
572 kiocb_cancel_fn *old, *cancel;
573
574 /*
575 * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
576 * actually has a cancel function, hence the cmpxchg()
577 */
578
579 cancel = READ_ONCE(kiocb->ki_cancel);
580 do {
581 if (!cancel || cancel == KIOCB_CANCELLED)
582 return -EINVAL;
583
584 old = cancel;
585 cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
586 } while (cancel != old);
587
588 return cancel(&kiocb->common);
589}
590
591/*
592 * free_ioctx() should be RCU delayed to synchronize against the RCU
593 * protected lookup_ioctx() and also needs process context to call
594 * aio_free_ring(). Use rcu_work.
595 */
596static void free_ioctx(struct work_struct *work)
597{
598 struct kioctx *ctx = container_of(to_rcu_work(work), struct kioctx,
599 free_rwork);
600 pr_debug("freeing %p\n", ctx);
601
602 aio_free_ring(ctx);
603 free_percpu(ctx->cpu);
604 percpu_ref_exit(&ctx->reqs);
605 percpu_ref_exit(&ctx->users);
606 kmem_cache_free(kioctx_cachep, ctx);
607}
608
609static void free_ioctx_reqs(struct percpu_ref *ref)
610{
611 struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
612
613 /* At this point we know that there are no any in-flight requests */
614 if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
615 complete(&ctx->rq_wait->comp);
616
617 /* Synchronize against RCU protected table->table[] dereferences */
618 INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
619 queue_rcu_work(system_wq, &ctx->free_rwork);
620}
621
622/*
623 * When this function runs, the kioctx has been removed from the "hash table"
624 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
625 * now it's safe to cancel any that need to be.
626 */
627static void free_ioctx_users(struct percpu_ref *ref)
628{
629 struct kioctx *ctx = container_of(ref, struct kioctx, users);
630 struct aio_kiocb *req;
631
632 spin_lock_irq(&ctx->ctx_lock);
633
634 while (!list_empty(&ctx->active_reqs)) {
635 req = list_first_entry(&ctx->active_reqs,
636 struct aio_kiocb, ki_list);
637 kiocb_cancel(req);
638 list_del_init(&req->ki_list);
639 }
640
641 spin_unlock_irq(&ctx->ctx_lock);
642
643 percpu_ref_kill(&ctx->reqs);
644 percpu_ref_put(&ctx->reqs);
645}
646
647static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
648{
649 unsigned i, new_nr;
650 struct kioctx_table *table, *old;
651 struct aio_ring *ring;
652
653 spin_lock(&mm->ioctx_lock);
654 table = rcu_dereference_raw(mm->ioctx_table);
655
656 while (1) {
657 if (table)
658 for (i = 0; i < table->nr; i++)
659 if (!rcu_access_pointer(table->table[i])) {
660 ctx->id = i;
661 rcu_assign_pointer(table->table[i], ctx);
662 spin_unlock(&mm->ioctx_lock);
663
664 /* While kioctx setup is in progress,
665 * we are protected from page migration
666 * changes ring_pages by ->ring_lock.
667 */
668 ring = kmap_atomic(ctx->ring_pages[0]);
669 ring->id = ctx->id;
670 kunmap_atomic(ring);
671 return 0;
672 }
673
674 new_nr = (table ? table->nr : 1) * 4;
675 spin_unlock(&mm->ioctx_lock);
676
677 table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) *
678 new_nr, GFP_KERNEL);
679 if (!table)
680 return -ENOMEM;
681
682 table->nr = new_nr;
683
684 spin_lock(&mm->ioctx_lock);
685 old = rcu_dereference_raw(mm->ioctx_table);
686
687 if (!old) {
688 rcu_assign_pointer(mm->ioctx_table, table);
689 } else if (table->nr > old->nr) {
690 memcpy(table->table, old->table,
691 old->nr * sizeof(struct kioctx *));
692
693 rcu_assign_pointer(mm->ioctx_table, table);
694 kfree_rcu(old, rcu);
695 } else {
696 kfree(table);
697 table = old;
698 }
699 }
700}
701
702static void aio_nr_sub(unsigned nr)
703{
704 spin_lock(&aio_nr_lock);
705 if (WARN_ON(aio_nr - nr > aio_nr))
706 aio_nr = 0;
707 else
708 aio_nr -= nr;
709 spin_unlock(&aio_nr_lock);
710}
711
712/* ioctx_alloc
713 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
714 */
715static struct kioctx *ioctx_alloc(unsigned nr_events)
716{
717 struct mm_struct *mm = current->mm;
718 struct kioctx *ctx;
719 int err = -ENOMEM;
720
721 /*
722 * Store the original nr_events -- what userspace passed to io_setup(),
723 * for counting against the global limit -- before it changes.
724 */
725 unsigned int max_reqs = nr_events;
726
727 /*
728 * We keep track of the number of available ringbuffer slots, to prevent
729 * overflow (reqs_available), and we also use percpu counters for this.
730 *
731 * So since up to half the slots might be on other cpu's percpu counters
732 * and unavailable, double nr_events so userspace sees what they
733 * expected: additionally, we move req_batch slots to/from percpu
734 * counters at a time, so make sure that isn't 0:
735 */
736 nr_events = max(nr_events, num_possible_cpus() * 4);
737 nr_events *= 2;
738
739 /* Prevent overflows */
740 if (nr_events > (0x10000000U / sizeof(struct io_event))) {
741 pr_debug("ENOMEM: nr_events too high\n");
742 return ERR_PTR(-EINVAL);
743 }
744
745 if (!nr_events || (unsigned long)max_reqs > aio_max_nr)
746 return ERR_PTR(-EAGAIN);
747
748 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
749 if (!ctx)
750 return ERR_PTR(-ENOMEM);
751
752 ctx->max_reqs = max_reqs;
753
754 spin_lock_init(&ctx->ctx_lock);
755 spin_lock_init(&ctx->completion_lock);
756 mutex_init(&ctx->ring_lock);
757 /* Protect against page migration throughout kiotx setup by keeping
758 * the ring_lock mutex held until setup is complete. */
759 mutex_lock(&ctx->ring_lock);
760 init_waitqueue_head(&ctx->wait);
761
762 INIT_LIST_HEAD(&ctx->active_reqs);
763
764 if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL))
765 goto err;
766
767 if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL))
768 goto err;
769
770 ctx->cpu = alloc_percpu(struct kioctx_cpu);
771 if (!ctx->cpu)
772 goto err;
773
774 err = aio_setup_ring(ctx, nr_events);
775 if (err < 0)
776 goto err;
777
778 atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
779 ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
780 if (ctx->req_batch < 1)
781 ctx->req_batch = 1;
782
783 /* limit the number of system wide aios */
784 spin_lock(&aio_nr_lock);
785 if (aio_nr + ctx->max_reqs > aio_max_nr ||
786 aio_nr + ctx->max_reqs < aio_nr) {
787 spin_unlock(&aio_nr_lock);
788 err = -EAGAIN;
789 goto err_ctx;
790 }
791 aio_nr += ctx->max_reqs;
792 spin_unlock(&aio_nr_lock);
793
794 percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */
795 percpu_ref_get(&ctx->reqs); /* free_ioctx_users() will drop this */
796
797 err = ioctx_add_table(ctx, mm);
798 if (err)
799 goto err_cleanup;
800
801 /* Release the ring_lock mutex now that all setup is complete. */
802 mutex_unlock(&ctx->ring_lock);
803
804 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
805 ctx, ctx->user_id, mm, ctx->nr_events);
806 return ctx;
807
808err_cleanup:
809 aio_nr_sub(ctx->max_reqs);
810err_ctx:
811 atomic_set(&ctx->dead, 1);
812 if (ctx->mmap_size)
813 vm_munmap(ctx->mmap_base, ctx->mmap_size);
814 aio_free_ring(ctx);
815err:
816 mutex_unlock(&ctx->ring_lock);
817 free_percpu(ctx->cpu);
818 percpu_ref_exit(&ctx->reqs);
819 percpu_ref_exit(&ctx->users);
820 kmem_cache_free(kioctx_cachep, ctx);
821 pr_debug("error allocating ioctx %d\n", err);
822 return ERR_PTR(err);
823}
824
825/* kill_ioctx
826 * Cancels all outstanding aio requests on an aio context. Used
827 * when the processes owning a context have all exited to encourage
828 * the rapid destruction of the kioctx.
829 */
830static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
831 struct ctx_rq_wait *wait)
832{
833 struct kioctx_table *table;
834
835 spin_lock(&mm->ioctx_lock);
836 if (atomic_xchg(&ctx->dead, 1)) {
837 spin_unlock(&mm->ioctx_lock);
838 return -EINVAL;
839 }
840
841 table = rcu_dereference_raw(mm->ioctx_table);
842 WARN_ON(ctx != rcu_access_pointer(table->table[ctx->id]));
843 RCU_INIT_POINTER(table->table[ctx->id], NULL);
844 spin_unlock(&mm->ioctx_lock);
845
846 /* free_ioctx_reqs() will do the necessary RCU synchronization */
847 wake_up_all(&ctx->wait);
848
849 /*
850 * It'd be more correct to do this in free_ioctx(), after all
851 * the outstanding kiocbs have finished - but by then io_destroy
852 * has already returned, so io_setup() could potentially return
853 * -EAGAIN with no ioctxs actually in use (as far as userspace
854 * could tell).
855 */
856 aio_nr_sub(ctx->max_reqs);
857
858 if (ctx->mmap_size)
859 vm_munmap(ctx->mmap_base, ctx->mmap_size);
860
861 ctx->rq_wait = wait;
862 percpu_ref_kill(&ctx->users);
863 return 0;
864}
865
866/*
867 * exit_aio: called when the last user of mm goes away. At this point, there is
868 * no way for any new requests to be submited or any of the io_* syscalls to be
869 * called on the context.
870 *
871 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
872 * them.
873 */
874void exit_aio(struct mm_struct *mm)
875{
876 struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
877 struct ctx_rq_wait wait;
878 int i, skipped;
879
880 if (!table)
881 return;
882
883 atomic_set(&wait.count, table->nr);
884 init_completion(&wait.comp);
885
886 skipped = 0;
887 for (i = 0; i < table->nr; ++i) {
888 struct kioctx *ctx =
889 rcu_dereference_protected(table->table[i], true);
890
891 if (!ctx) {
892 skipped++;
893 continue;
894 }
895
896 /*
897 * We don't need to bother with munmap() here - exit_mmap(mm)
898 * is coming and it'll unmap everything. And we simply can't,
899 * this is not necessarily our ->mm.
900 * Since kill_ioctx() uses non-zero ->mmap_size as indicator
901 * that it needs to unmap the area, just set it to 0.
902 */
903 ctx->mmap_size = 0;
904 kill_ioctx(mm, ctx, &wait);
905 }
906
907 if (!atomic_sub_and_test(skipped, &wait.count)) {
908 /* Wait until all IO for the context are done. */
909 wait_for_completion(&wait.comp);
910 }
911
912 RCU_INIT_POINTER(mm->ioctx_table, NULL);
913 kfree(table);
914}
915
916static void put_reqs_available(struct kioctx *ctx, unsigned nr)
917{
918 struct kioctx_cpu *kcpu;
919 unsigned long flags;
920
921 local_irq_save(flags);
922 kcpu = this_cpu_ptr(ctx->cpu);
923 kcpu->reqs_available += nr;
924
925 while (kcpu->reqs_available >= ctx->req_batch * 2) {
926 kcpu->reqs_available -= ctx->req_batch;
927 atomic_add(ctx->req_batch, &ctx->reqs_available);
928 }
929
930 local_irq_restore(flags);
931}
932
933static bool get_reqs_available(struct kioctx *ctx)
934{
935 struct kioctx_cpu *kcpu;
936 bool ret = false;
937 unsigned long flags;
938
939 local_irq_save(flags);
940 kcpu = this_cpu_ptr(ctx->cpu);
941 if (!kcpu->reqs_available) {
942 int old, avail = atomic_read(&ctx->reqs_available);
943
944 do {
945 if (avail < ctx->req_batch)
946 goto out;
947
948 old = avail;
949 avail = atomic_cmpxchg(&ctx->reqs_available,
950 avail, avail - ctx->req_batch);
951 } while (avail != old);
952
953 kcpu->reqs_available += ctx->req_batch;
954 }
955
956 ret = true;
957 kcpu->reqs_available--;
958out:
959 local_irq_restore(flags);
960 return ret;
961}
962
963/* refill_reqs_available
964 * Updates the reqs_available reference counts used for tracking the
965 * number of free slots in the completion ring. This can be called
966 * from aio_complete() (to optimistically update reqs_available) or
967 * from aio_get_req() (the we're out of events case). It must be
968 * called holding ctx->completion_lock.
969 */
970static void refill_reqs_available(struct kioctx *ctx, unsigned head,
971 unsigned tail)
972{
973 unsigned events_in_ring, completed;
974
975 /* Clamp head since userland can write to it. */
976 head %= ctx->nr_events;
977 if (head <= tail)
978 events_in_ring = tail - head;
979 else
980 events_in_ring = ctx->nr_events - (head - tail);
981
982 completed = ctx->completed_events;
983 if (events_in_ring < completed)
984 completed -= events_in_ring;
985 else
986 completed = 0;
987
988 if (!completed)
989 return;
990
991 ctx->completed_events -= completed;
992 put_reqs_available(ctx, completed);
993}
994
995/* user_refill_reqs_available
996 * Called to refill reqs_available when aio_get_req() encounters an
997 * out of space in the completion ring.
998 */
999static void user_refill_reqs_available(struct kioctx *ctx)
1000{
1001 spin_lock_irq(&ctx->completion_lock);
1002 if (ctx->completed_events) {
1003 struct aio_ring *ring;
1004 unsigned head;
1005
1006 /* Access of ring->head may race with aio_read_events_ring()
1007 * here, but that's okay since whether we read the old version
1008 * or the new version, and either will be valid. The important
1009 * part is that head cannot pass tail since we prevent
1010 * aio_complete() from updating tail by holding
1011 * ctx->completion_lock. Even if head is invalid, the check
1012 * against ctx->completed_events below will make sure we do the
1013 * safe/right thing.
1014 */
1015 ring = kmap_atomic(ctx->ring_pages[0]);
1016 head = ring->head;
1017 kunmap_atomic(ring);
1018
1019 refill_reqs_available(ctx, head, ctx->tail);
1020 }
1021
1022 spin_unlock_irq(&ctx->completion_lock);
1023}
1024
1025/* aio_get_req
1026 * Allocate a slot for an aio request.
1027 * Returns NULL if no requests are free.
1028 */
1029static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
1030{
1031 struct aio_kiocb *req;
1032
1033 if (!get_reqs_available(ctx)) {
1034 user_refill_reqs_available(ctx);
1035 if (!get_reqs_available(ctx))
1036 return NULL;
1037 }
1038
1039 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
1040 if (unlikely(!req))
1041 goto out_put;
1042
1043 percpu_ref_get(&ctx->reqs);
1044
1045 req->ki_ctx = ctx;
1046 return req;
1047out_put:
1048 put_reqs_available(ctx, 1);
1049 return NULL;
1050}
1051
1052static void kiocb_free(struct aio_kiocb *req)
1053{
1054 if (req->common.ki_filp)
1055 fput(req->common.ki_filp);
1056 if (req->ki_eventfd != NULL)
1057 eventfd_ctx_put(req->ki_eventfd);
1058 kmem_cache_free(kiocb_cachep, req);
1059}
1060
1061static struct kioctx *lookup_ioctx(unsigned long ctx_id)
1062{
1063 struct aio_ring __user *ring = (void __user *)ctx_id;
1064 struct mm_struct *mm = current->mm;
1065 struct kioctx *ctx, *ret = NULL;
1066 struct kioctx_table *table;
1067 unsigned id;
1068
1069 if (get_user(id, &ring->id))
1070 return NULL;
1071
1072 rcu_read_lock();
1073 table = rcu_dereference(mm->ioctx_table);
1074
1075 if (!table || id >= table->nr)
1076 goto out;
1077
1078 ctx = rcu_dereference(table->table[id]);
1079 if (ctx && ctx->user_id == ctx_id) {
1080 if (percpu_ref_tryget_live(&ctx->users))
1081 ret = ctx;
1082 }
1083out:
1084 rcu_read_unlock();
1085 return ret;
1086}
1087
1088/* aio_complete
1089 * Called when the io request on the given iocb is complete.
1090 */
1091static void aio_complete(struct kiocb *kiocb, long res, long res2)
1092{
1093 struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, common);
1094 struct kioctx *ctx = iocb->ki_ctx;
1095 struct aio_ring *ring;
1096 struct io_event *ev_page, *event;
1097 unsigned tail, pos, head;
1098 unsigned long flags;
1099
1100 if (kiocb->ki_flags & IOCB_WRITE) {
1101 struct file *file = kiocb->ki_filp;
1102
1103 /*
1104 * Tell lockdep we inherited freeze protection from submission
1105 * thread.
1106 */
1107 if (S_ISREG(file_inode(file)->i_mode))
1108 __sb_writers_acquired(file_inode(file)->i_sb, SB_FREEZE_WRITE);
1109 file_end_write(file);
1110 }
1111
1112 /*
1113 * Special case handling for sync iocbs:
1114 * - events go directly into the iocb for fast handling
1115 * - the sync task with the iocb in its stack holds the single iocb
1116 * ref, no other paths have a way to get another ref
1117 * - the sync task helpfully left a reference to itself in the iocb
1118 */
1119 BUG_ON(is_sync_kiocb(kiocb));
1120
1121 if (iocb->ki_list.next) {
1122 unsigned long flags;
1123
1124 spin_lock_irqsave(&ctx->ctx_lock, flags);
1125 list_del(&iocb->ki_list);
1126 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1127 }
1128
1129 /*
1130 * Add a completion event to the ring buffer. Must be done holding
1131 * ctx->completion_lock to prevent other code from messing with the tail
1132 * pointer since we might be called from irq context.
1133 */
1134 spin_lock_irqsave(&ctx->completion_lock, flags);
1135
1136 tail = ctx->tail;
1137 pos = tail + AIO_EVENTS_OFFSET;
1138
1139 if (++tail >= ctx->nr_events)
1140 tail = 0;
1141
1142 ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1143 event = ev_page + pos % AIO_EVENTS_PER_PAGE;
1144
1145 event->obj = (u64)(unsigned long)iocb->ki_user_iocb;
1146 event->data = iocb->ki_user_data;
1147 event->res = res;
1148 event->res2 = res2;
1149
1150 kunmap_atomic(ev_page);
1151 flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1152
1153 pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
1154 ctx, tail, iocb, iocb->ki_user_iocb, iocb->ki_user_data,
1155 res, res2);
1156
1157 /* after flagging the request as done, we
1158 * must never even look at it again
1159 */
1160 smp_wmb(); /* make event visible before updating tail */
1161
1162 ctx->tail = tail;
1163
1164 ring = kmap_atomic(ctx->ring_pages[0]);
1165 head = ring->head;
1166 ring->tail = tail;
1167 kunmap_atomic(ring);
1168 flush_dcache_page(ctx->ring_pages[0]);
1169
1170 ctx->completed_events++;
1171 if (ctx->completed_events > 1)
1172 refill_reqs_available(ctx, head, tail);
1173 spin_unlock_irqrestore(&ctx->completion_lock, flags);
1174
1175 pr_debug("added to ring %p at [%u]\n", iocb, tail);
1176
1177 /*
1178 * Check if the user asked us to deliver the result through an
1179 * eventfd. The eventfd_signal() function is safe to be called
1180 * from IRQ context.
1181 */
1182 if (iocb->ki_eventfd != NULL)
1183 eventfd_signal(iocb->ki_eventfd, 1);
1184
1185 /* everything turned out well, dispose of the aiocb. */
1186 kiocb_free(iocb);
1187
1188 /*
1189 * We have to order our ring_info tail store above and test
1190 * of the wait list below outside the wait lock. This is
1191 * like in wake_up_bit() where clearing a bit has to be
1192 * ordered with the unlocked test.
1193 */
1194 smp_mb();
1195
1196 if (waitqueue_active(&ctx->wait))
1197 wake_up(&ctx->wait);
1198
1199 percpu_ref_put(&ctx->reqs);
1200}
1201
1202/* aio_read_events_ring
1203 * Pull an event off of the ioctx's event ring. Returns the number of
1204 * events fetched
1205 */
1206static long aio_read_events_ring(struct kioctx *ctx,
1207 struct io_event __user *event, long nr)
1208{
1209 struct aio_ring *ring;
1210 unsigned head, tail, pos;
1211 long ret = 0;
1212 int copy_ret;
1213
1214 /*
1215 * The mutex can block and wake us up and that will cause
1216 * wait_event_interruptible_hrtimeout() to schedule without sleeping
1217 * and repeat. This should be rare enough that it doesn't cause
1218 * peformance issues. See the comment in read_events() for more detail.
1219 */
1220 sched_annotate_sleep();
1221 mutex_lock(&ctx->ring_lock);
1222
1223 /* Access to ->ring_pages here is protected by ctx->ring_lock. */
1224 ring = kmap_atomic(ctx->ring_pages[0]);
1225 head = ring->head;
1226 tail = ring->tail;
1227 kunmap_atomic(ring);
1228
1229 /*
1230 * Ensure that once we've read the current tail pointer, that
1231 * we also see the events that were stored up to the tail.
1232 */
1233 smp_rmb();
1234
1235 pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
1236
1237 if (head == tail)
1238 goto out;
1239
1240 head %= ctx->nr_events;
1241 tail %= ctx->nr_events;
1242
1243 while (ret < nr) {
1244 long avail;
1245 struct io_event *ev;
1246 struct page *page;
1247
1248 avail = (head <= tail ? tail : ctx->nr_events) - head;
1249 if (head == tail)
1250 break;
1251
1252 avail = min(avail, nr - ret);
1253 avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
1254 ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
1255
1256 pos = head + AIO_EVENTS_OFFSET;
1257 page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
1258 pos %= AIO_EVENTS_PER_PAGE;
1259
1260 ev = kmap(page);
1261 copy_ret = copy_to_user(event + ret, ev + pos,
1262 sizeof(*ev) * avail);
1263 kunmap(page);
1264
1265 if (unlikely(copy_ret)) {
1266 ret = -EFAULT;
1267 goto out;
1268 }
1269
1270 ret += avail;
1271 head += avail;
1272 head %= ctx->nr_events;
1273 }
1274
1275 ring = kmap_atomic(ctx->ring_pages[0]);
1276 ring->head = head;
1277 kunmap_atomic(ring);
1278 flush_dcache_page(ctx->ring_pages[0]);
1279
1280 pr_debug("%li h%u t%u\n", ret, head, tail);
1281out:
1282 mutex_unlock(&ctx->ring_lock);
1283
1284 return ret;
1285}
1286
1287static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
1288 struct io_event __user *event, long *i)
1289{
1290 long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
1291
1292 if (ret > 0)
1293 *i += ret;
1294
1295 if (unlikely(atomic_read(&ctx->dead)))
1296 ret = -EINVAL;
1297
1298 if (!*i)
1299 *i = ret;
1300
1301 return ret < 0 || *i >= min_nr;
1302}
1303
1304static long read_events(struct kioctx *ctx, long min_nr, long nr,
1305 struct io_event __user *event,
1306 ktime_t until)
1307{
1308 long ret = 0;
1309
1310 /*
1311 * Note that aio_read_events() is being called as the conditional - i.e.
1312 * we're calling it after prepare_to_wait() has set task state to
1313 * TASK_INTERRUPTIBLE.
1314 *
1315 * But aio_read_events() can block, and if it blocks it's going to flip
1316 * the task state back to TASK_RUNNING.
1317 *
1318 * This should be ok, provided it doesn't flip the state back to
1319 * TASK_RUNNING and return 0 too much - that causes us to spin. That
1320 * will only happen if the mutex_lock() call blocks, and we then find
1321 * the ringbuffer empty. So in practice we should be ok, but it's
1322 * something to be aware of when touching this code.
1323 */
1324 if (until == 0)
1325 aio_read_events(ctx, min_nr, nr, event, &ret);
1326 else
1327 wait_event_interruptible_hrtimeout(ctx->wait,
1328 aio_read_events(ctx, min_nr, nr, event, &ret),
1329 until);
1330
1331 if (!ret && signal_pending(current))
1332 ret = -EINTR;
1333
1334 return ret;
1335}
1336
1337/* sys_io_setup:
1338 * Create an aio_context capable of receiving at least nr_events.
1339 * ctxp must not point to an aio_context that already exists, and
1340 * must be initialized to 0 prior to the call. On successful
1341 * creation of the aio_context, *ctxp is filled in with the resulting
1342 * handle. May fail with -EINVAL if *ctxp is not initialized,
1343 * if the specified nr_events exceeds internal limits. May fail
1344 * with -EAGAIN if the specified nr_events exceeds the user's limit
1345 * of available events. May fail with -ENOMEM if insufficient kernel
1346 * resources are available. May fail with -EFAULT if an invalid
1347 * pointer is passed for ctxp. Will fail with -ENOSYS if not
1348 * implemented.
1349 */
1350SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1351{
1352 struct kioctx *ioctx = NULL;
1353 unsigned long ctx;
1354 long ret;
1355
1356 ret = get_user(ctx, ctxp);
1357 if (unlikely(ret))
1358 goto out;
1359
1360 ret = -EINVAL;
1361 if (unlikely(ctx || nr_events == 0)) {
1362 pr_debug("EINVAL: ctx %lu nr_events %u\n",
1363 ctx, nr_events);
1364 goto out;
1365 }
1366
1367 ioctx = ioctx_alloc(nr_events);
1368 ret = PTR_ERR(ioctx);
1369 if (!IS_ERR(ioctx)) {
1370 ret = put_user(ioctx->user_id, ctxp);
1371 if (ret)
1372 kill_ioctx(current->mm, ioctx, NULL);
1373 percpu_ref_put(&ioctx->users);
1374 }
1375
1376out:
1377 return ret;
1378}
1379
1380#ifdef CONFIG_COMPAT
1381COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
1382{
1383 struct kioctx *ioctx = NULL;
1384 unsigned long ctx;
1385 long ret;
1386
1387 ret = get_user(ctx, ctx32p);
1388 if (unlikely(ret))
1389 goto out;
1390
1391 ret = -EINVAL;
1392 if (unlikely(ctx || nr_events == 0)) {
1393 pr_debug("EINVAL: ctx %lu nr_events %u\n",
1394 ctx, nr_events);
1395 goto out;
1396 }
1397
1398 ioctx = ioctx_alloc(nr_events);
1399 ret = PTR_ERR(ioctx);
1400 if (!IS_ERR(ioctx)) {
1401 /* truncating is ok because it's a user address */
1402 ret = put_user((u32)ioctx->user_id, ctx32p);
1403 if (ret)
1404 kill_ioctx(current->mm, ioctx, NULL);
1405 percpu_ref_put(&ioctx->users);
1406 }
1407
1408out:
1409 return ret;
1410}
1411#endif
1412
1413/* sys_io_destroy:
1414 * Destroy the aio_context specified. May cancel any outstanding
1415 * AIOs and block on completion. Will fail with -ENOSYS if not
1416 * implemented. May fail with -EINVAL if the context pointed to
1417 * is invalid.
1418 */
1419SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1420{
1421 struct kioctx *ioctx = lookup_ioctx(ctx);
1422 if (likely(NULL != ioctx)) {
1423 struct ctx_rq_wait wait;
1424 int ret;
1425
1426 init_completion(&wait.comp);
1427 atomic_set(&wait.count, 1);
1428
1429 /* Pass requests_done to kill_ioctx() where it can be set
1430 * in a thread-safe way. If we try to set it here then we have
1431 * a race condition if two io_destroy() called simultaneously.
1432 */
1433 ret = kill_ioctx(current->mm, ioctx, &wait);
1434 percpu_ref_put(&ioctx->users);
1435
1436 /* Wait until all IO for the context are done. Otherwise kernel
1437 * keep using user-space buffers even if user thinks the context
1438 * is destroyed.
1439 */
1440 if (!ret)
1441 wait_for_completion(&wait.comp);
1442
1443 return ret;
1444 }
1445 pr_debug("EINVAL: invalid context id\n");
1446 return -EINVAL;
1447}
1448
1449static int aio_setup_rw(int rw, struct iocb *iocb, struct iovec **iovec,
1450 bool vectored, bool compat, struct iov_iter *iter)
1451{
1452 void __user *buf = (void __user *)(uintptr_t)iocb->aio_buf;
1453 size_t len = iocb->aio_nbytes;
1454
1455 if (!vectored) {
1456 ssize_t ret = import_single_range(rw, buf, len, *iovec, iter);
1457 *iovec = NULL;
1458 return ret;
1459 }
1460#ifdef CONFIG_COMPAT
1461 if (compat)
1462 return compat_import_iovec(rw, buf, len, UIO_FASTIOV, iovec,
1463 iter);
1464#endif
1465 return import_iovec(rw, buf, len, UIO_FASTIOV, iovec, iter);
1466}
1467
1468static inline ssize_t aio_ret(struct kiocb *req, ssize_t ret)
1469{
1470 switch (ret) {
1471 case -EIOCBQUEUED:
1472 return ret;
1473 case -ERESTARTSYS:
1474 case -ERESTARTNOINTR:
1475 case -ERESTARTNOHAND:
1476 case -ERESTART_RESTARTBLOCK:
1477 /*
1478 * There's no easy way to restart the syscall since other AIO's
1479 * may be already running. Just fail this IO with EINTR.
1480 */
1481 ret = -EINTR;
1482 /*FALLTHRU*/
1483 default:
1484 aio_complete(req, ret, 0);
1485 return 0;
1486 }
1487}
1488
1489static ssize_t aio_read(struct kiocb *req, struct iocb *iocb, bool vectored,
1490 bool compat)
1491{
1492 struct file *file = req->ki_filp;
1493 struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1494 struct iov_iter iter;
1495 ssize_t ret;
1496
1497 if (unlikely(!(file->f_mode & FMODE_READ)))
1498 return -EBADF;
1499 if (unlikely(!file->f_op->read_iter))
1500 return -EINVAL;
1501
1502 ret = aio_setup_rw(READ, iocb, &iovec, vectored, compat, &iter);
1503 if (ret)
1504 return ret;
1505 ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(&iter));
1506 if (!ret)
1507 ret = aio_ret(req, call_read_iter(file, req, &iter));
1508 kfree(iovec);
1509 return ret;
1510}
1511
1512static ssize_t aio_write(struct kiocb *req, struct iocb *iocb, bool vectored,
1513 bool compat)
1514{
1515 struct file *file = req->ki_filp;
1516 struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1517 struct iov_iter iter;
1518 ssize_t ret;
1519
1520 if (unlikely(!(file->f_mode & FMODE_WRITE)))
1521 return -EBADF;
1522 if (unlikely(!file->f_op->write_iter))
1523 return -EINVAL;
1524
1525 ret = aio_setup_rw(WRITE, iocb, &iovec, vectored, compat, &iter);
1526 if (ret)
1527 return ret;
1528 ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
1529 if (!ret) {
1530 req->ki_flags |= IOCB_WRITE;
1531 file_start_write(file);
1532 ret = aio_ret(req, call_write_iter(file, req, &iter));
1533 /*
1534 * We release freeze protection in aio_complete(). Fool lockdep
1535 * by telling it the lock got released so that it doesn't
1536 * complain about held lock when we return to userspace.
1537 */
1538 if (S_ISREG(file_inode(file)->i_mode))
1539 __sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
1540 }
1541 kfree(iovec);
1542 return ret;
1543}
1544
1545static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1546 struct iocb *iocb, bool compat)
1547{
1548 struct aio_kiocb *req;
1549 struct file *file;
1550 ssize_t ret;
1551
1552 /* enforce forwards compatibility on users */
1553 if (unlikely(iocb->aio_reserved2)) {
1554 pr_debug("EINVAL: reserve field set\n");
1555 return -EINVAL;
1556 }
1557
1558 /* prevent overflows */
1559 if (unlikely(
1560 (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
1561 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
1562 ((ssize_t)iocb->aio_nbytes < 0)
1563 )) {
1564 pr_debug("EINVAL: overflow check\n");
1565 return -EINVAL;
1566 }
1567
1568 req = aio_get_req(ctx);
1569 if (unlikely(!req))
1570 return -EAGAIN;
1571
1572 req->common.ki_filp = file = fget(iocb->aio_fildes);
1573 if (unlikely(!req->common.ki_filp)) {
1574 ret = -EBADF;
1575 goto out_put_req;
1576 }
1577 req->common.ki_pos = iocb->aio_offset;
1578 req->common.ki_complete = aio_complete;
1579 req->common.ki_flags = iocb_flags(req->common.ki_filp);
1580 req->common.ki_hint = file_write_hint(file);
1581
1582 if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1583 /*
1584 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1585 * instance of the file* now. The file descriptor must be
1586 * an eventfd() fd, and will be signaled for each completed
1587 * event using the eventfd_signal() function.
1588 */
1589 req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
1590 if (IS_ERR(req->ki_eventfd)) {
1591 ret = PTR_ERR(req->ki_eventfd);
1592 req->ki_eventfd = NULL;
1593 goto out_put_req;
1594 }
1595
1596 req->common.ki_flags |= IOCB_EVENTFD;
1597 }
1598
1599 ret = kiocb_set_rw_flags(&req->common, iocb->aio_rw_flags);
1600 if (unlikely(ret)) {
1601 pr_debug("EINVAL: aio_rw_flags\n");
1602 goto out_put_req;
1603 }
1604
1605 ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
1606 if (unlikely(ret)) {
1607 pr_debug("EFAULT: aio_key\n");
1608 goto out_put_req;
1609 }
1610
1611 req->ki_user_iocb = user_iocb;
1612 req->ki_user_data = iocb->aio_data;
1613
1614 get_file(file);
1615 switch (iocb->aio_lio_opcode) {
1616 case IOCB_CMD_PREAD:
1617 ret = aio_read(&req->common, iocb, false, compat);
1618 break;
1619 case IOCB_CMD_PWRITE:
1620 ret = aio_write(&req->common, iocb, false, compat);
1621 break;
1622 case IOCB_CMD_PREADV:
1623 ret = aio_read(&req->common, iocb, true, compat);
1624 break;
1625 case IOCB_CMD_PWRITEV:
1626 ret = aio_write(&req->common, iocb, true, compat);
1627 break;
1628 default:
1629 pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
1630 ret = -EINVAL;
1631 break;
1632 }
1633 fput(file);
1634
1635 if (ret && ret != -EIOCBQUEUED)
1636 goto out_put_req;
1637 return 0;
1638out_put_req:
1639 put_reqs_available(ctx, 1);
1640 percpu_ref_put(&ctx->reqs);
1641 kiocb_free(req);
1642 return ret;
1643}
1644
1645static long do_io_submit(aio_context_t ctx_id, long nr,
1646 struct iocb __user *__user *iocbpp, bool compat)
1647{
1648 struct kioctx *ctx;
1649 long ret = 0;
1650 int i = 0;
1651 struct blk_plug plug;
1652
1653 if (unlikely(nr < 0))
1654 return -EINVAL;
1655
1656 if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
1657 nr = LONG_MAX/sizeof(*iocbpp);
1658
1659 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1660 return -EFAULT;
1661
1662 ctx = lookup_ioctx(ctx_id);
1663 if (unlikely(!ctx)) {
1664 pr_debug("EINVAL: invalid context id\n");
1665 return -EINVAL;
1666 }
1667
1668 blk_start_plug(&plug);
1669
1670 /*
1671 * AKPM: should this return a partial result if some of the IOs were
1672 * successfully submitted?
1673 */
1674 for (i=0; i<nr; i++) {
1675 struct iocb __user *user_iocb;
1676 struct iocb tmp;
1677
1678 if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1679 ret = -EFAULT;
1680 break;
1681 }
1682
1683 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1684 ret = -EFAULT;
1685 break;
1686 }
1687
1688 ret = io_submit_one(ctx, user_iocb, &tmp, compat);
1689 if (ret)
1690 break;
1691 }
1692 blk_finish_plug(&plug);
1693
1694 percpu_ref_put(&ctx->users);
1695 return i ? i : ret;
1696}
1697
1698/* sys_io_submit:
1699 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1700 * the number of iocbs queued. May return -EINVAL if the aio_context
1701 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1702 * *iocbpp[0] is not properly initialized, if the operation specified
1703 * is invalid for the file descriptor in the iocb. May fail with
1704 * -EFAULT if any of the data structures point to invalid data. May
1705 * fail with -EBADF if the file descriptor specified in the first
1706 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1707 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1708 * fail with -ENOSYS if not implemented.
1709 */
1710SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
1711 struct iocb __user * __user *, iocbpp)
1712{
1713 return do_io_submit(ctx_id, nr, iocbpp, 0);
1714}
1715
1716#ifdef CONFIG_COMPAT
1717static inline long
1718copy_iocb(long nr, u32 __user *ptr32, struct iocb __user * __user *ptr64)
1719{
1720 compat_uptr_t uptr;
1721 int i;
1722
1723 for (i = 0; i < nr; ++i) {
1724 if (get_user(uptr, ptr32 + i))
1725 return -EFAULT;
1726 if (put_user(compat_ptr(uptr), ptr64 + i))
1727 return -EFAULT;
1728 }
1729 return 0;
1730}
1731
1732#define MAX_AIO_SUBMITS (PAGE_SIZE/sizeof(struct iocb *))
1733
1734COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
1735 int, nr, u32 __user *, iocb)
1736{
1737 struct iocb __user * __user *iocb64;
1738 long ret;
1739
1740 if (unlikely(nr < 0))
1741 return -EINVAL;
1742
1743 if (nr > MAX_AIO_SUBMITS)
1744 nr = MAX_AIO_SUBMITS;
1745
1746 iocb64 = compat_alloc_user_space(nr * sizeof(*iocb64));
1747 ret = copy_iocb(nr, iocb, iocb64);
1748 if (!ret)
1749 ret = do_io_submit(ctx_id, nr, iocb64, 1);
1750 return ret;
1751}
1752#endif
1753
1754/* lookup_kiocb
1755 * Finds a given iocb for cancellation.
1756 */
1757static struct aio_kiocb *
1758lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, u32 key)
1759{
1760 struct aio_kiocb *kiocb;
1761
1762 assert_spin_locked(&ctx->ctx_lock);
1763
1764 if (key != KIOCB_KEY)
1765 return NULL;
1766
1767 /* TODO: use a hash or array, this sucks. */
1768 list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
1769 if (kiocb->ki_user_iocb == iocb)
1770 return kiocb;
1771 }
1772 return NULL;
1773}
1774
1775/* sys_io_cancel:
1776 * Attempts to cancel an iocb previously passed to io_submit. If
1777 * the operation is successfully cancelled, the resulting event is
1778 * copied into the memory pointed to by result without being placed
1779 * into the completion queue and 0 is returned. May fail with
1780 * -EFAULT if any of the data structures pointed to are invalid.
1781 * May fail with -EINVAL if aio_context specified by ctx_id is
1782 * invalid. May fail with -EAGAIN if the iocb specified was not
1783 * cancelled. Will fail with -ENOSYS if not implemented.
1784 */
1785SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
1786 struct io_event __user *, result)
1787{
1788 struct kioctx *ctx;
1789 struct aio_kiocb *kiocb;
1790 u32 key;
1791 int ret;
1792
1793 ret = get_user(key, &iocb->aio_key);
1794 if (unlikely(ret))
1795 return -EFAULT;
1796
1797 ctx = lookup_ioctx(ctx_id);
1798 if (unlikely(!ctx))
1799 return -EINVAL;
1800
1801 spin_lock_irq(&ctx->ctx_lock);
1802
1803 kiocb = lookup_kiocb(ctx, iocb, key);
1804 if (kiocb)
1805 ret = kiocb_cancel(kiocb);
1806 else
1807 ret = -EINVAL;
1808
1809 spin_unlock_irq(&ctx->ctx_lock);
1810
1811 if (!ret) {
1812 /*
1813 * The result argument is no longer used - the io_event is
1814 * always delivered via the ring buffer. -EINPROGRESS indicates
1815 * cancellation is progress:
1816 */
1817 ret = -EINPROGRESS;
1818 }
1819
1820 percpu_ref_put(&ctx->users);
1821
1822 return ret;
1823}
1824
1825static long do_io_getevents(aio_context_t ctx_id,
1826 long min_nr,
1827 long nr,
1828 struct io_event __user *events,
1829 struct timespec64 *ts)
1830{
1831 ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
1832 struct kioctx *ioctx = lookup_ioctx(ctx_id);
1833 long ret = -EINVAL;
1834
1835 if (likely(ioctx)) {
1836 if (likely(min_nr <= nr && min_nr >= 0))
1837 ret = read_events(ioctx, min_nr, nr, events, until);
1838 percpu_ref_put(&ioctx->users);
1839 }
1840
1841 return ret;
1842}
1843
1844/* io_getevents:
1845 * Attempts to read at least min_nr events and up to nr events from
1846 * the completion queue for the aio_context specified by ctx_id. If
1847 * it succeeds, the number of read events is returned. May fail with
1848 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
1849 * out of range, if timeout is out of range. May fail with -EFAULT
1850 * if any of the memory specified is invalid. May return 0 or
1851 * < min_nr if the timeout specified by timeout has elapsed
1852 * before sufficient events are available, where timeout == NULL
1853 * specifies an infinite timeout. Note that the timeout pointed to by
1854 * timeout is relative. Will fail with -ENOSYS if not implemented.
1855 */
1856SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
1857 long, min_nr,
1858 long, nr,
1859 struct io_event __user *, events,
1860 struct timespec __user *, timeout)
1861{
1862 struct timespec64 ts;
1863
1864 if (timeout) {
1865 if (unlikely(get_timespec64(&ts, timeout)))
1866 return -EFAULT;
1867 }
1868
1869 return do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
1870}
1871
1872#ifdef CONFIG_COMPAT
1873COMPAT_SYSCALL_DEFINE5(io_getevents, compat_aio_context_t, ctx_id,
1874 compat_long_t, min_nr,
1875 compat_long_t, nr,
1876 struct io_event __user *, events,
1877 struct compat_timespec __user *, timeout)
1878{
1879 struct timespec64 t;
1880
1881 if (timeout) {
1882 if (compat_get_timespec64(&t, timeout))
1883 return -EFAULT;
1884
1885 }
1886
1887 return do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
1888}
1889#endif
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 *
9 * See ../COPYING for licensing terms.
10 */
11#define pr_fmt(fmt) "%s: " fmt, __func__
12
13#include <linux/kernel.h>
14#include <linux/init.h>
15#include <linux/errno.h>
16#include <linux/time.h>
17#include <linux/aio_abi.h>
18#include <linux/export.h>
19#include <linux/syscalls.h>
20#include <linux/backing-dev.h>
21#include <linux/uio.h>
22
23#include <linux/sched.h>
24#include <linux/fs.h>
25#include <linux/file.h>
26#include <linux/mm.h>
27#include <linux/mman.h>
28#include <linux/mmu_context.h>
29#include <linux/percpu.h>
30#include <linux/slab.h>
31#include <linux/timer.h>
32#include <linux/aio.h>
33#include <linux/highmem.h>
34#include <linux/workqueue.h>
35#include <linux/security.h>
36#include <linux/eventfd.h>
37#include <linux/blkdev.h>
38#include <linux/compat.h>
39#include <linux/migrate.h>
40#include <linux/ramfs.h>
41#include <linux/percpu-refcount.h>
42#include <linux/mount.h>
43
44#include <asm/kmap_types.h>
45#include <asm/uaccess.h>
46
47#include "internal.h"
48
49#define AIO_RING_MAGIC 0xa10a10a1
50#define AIO_RING_COMPAT_FEATURES 1
51#define AIO_RING_INCOMPAT_FEATURES 0
52struct aio_ring {
53 unsigned id; /* kernel internal index number */
54 unsigned nr; /* number of io_events */
55 unsigned head; /* Written to by userland or under ring_lock
56 * mutex by aio_read_events_ring(). */
57 unsigned tail;
58
59 unsigned magic;
60 unsigned compat_features;
61 unsigned incompat_features;
62 unsigned header_length; /* size of aio_ring */
63
64
65 struct io_event io_events[0];
66}; /* 128 bytes + ring size */
67
68#define AIO_RING_PAGES 8
69
70struct kioctx_table {
71 struct rcu_head rcu;
72 unsigned nr;
73 struct kioctx *table[];
74};
75
76struct kioctx_cpu {
77 unsigned reqs_available;
78};
79
80struct ctx_rq_wait {
81 struct completion comp;
82 atomic_t count;
83};
84
85struct kioctx {
86 struct percpu_ref users;
87 atomic_t dead;
88
89 struct percpu_ref reqs;
90
91 unsigned long user_id;
92
93 struct __percpu kioctx_cpu *cpu;
94
95 /*
96 * For percpu reqs_available, number of slots we move to/from global
97 * counter at a time:
98 */
99 unsigned req_batch;
100 /*
101 * This is what userspace passed to io_setup(), it's not used for
102 * anything but counting against the global max_reqs quota.
103 *
104 * The real limit is nr_events - 1, which will be larger (see
105 * aio_setup_ring())
106 */
107 unsigned max_reqs;
108
109 /* Size of ringbuffer, in units of struct io_event */
110 unsigned nr_events;
111
112 unsigned long mmap_base;
113 unsigned long mmap_size;
114
115 struct page **ring_pages;
116 long nr_pages;
117
118 struct work_struct free_work;
119
120 /*
121 * signals when all in-flight requests are done
122 */
123 struct ctx_rq_wait *rq_wait;
124
125 struct {
126 /*
127 * This counts the number of available slots in the ringbuffer,
128 * so we avoid overflowing it: it's decremented (if positive)
129 * when allocating a kiocb and incremented when the resulting
130 * io_event is pulled off the ringbuffer.
131 *
132 * We batch accesses to it with a percpu version.
133 */
134 atomic_t reqs_available;
135 } ____cacheline_aligned_in_smp;
136
137 struct {
138 spinlock_t ctx_lock;
139 struct list_head active_reqs; /* used for cancellation */
140 } ____cacheline_aligned_in_smp;
141
142 struct {
143 struct mutex ring_lock;
144 wait_queue_head_t wait;
145 } ____cacheline_aligned_in_smp;
146
147 struct {
148 unsigned tail;
149 unsigned completed_events;
150 spinlock_t completion_lock;
151 } ____cacheline_aligned_in_smp;
152
153 struct page *internal_pages[AIO_RING_PAGES];
154 struct file *aio_ring_file;
155
156 unsigned id;
157};
158
159/*
160 * We use ki_cancel == KIOCB_CANCELLED to indicate that a kiocb has been either
161 * cancelled or completed (this makes a certain amount of sense because
162 * successful cancellation - io_cancel() - does deliver the completion to
163 * userspace).
164 *
165 * And since most things don't implement kiocb cancellation and we'd really like
166 * kiocb completion to be lockless when possible, we use ki_cancel to
167 * synchronize cancellation and completion - we only set it to KIOCB_CANCELLED
168 * with xchg() or cmpxchg(), see batch_complete_aio() and kiocb_cancel().
169 */
170#define KIOCB_CANCELLED ((void *) (~0ULL))
171
172struct aio_kiocb {
173 struct kiocb common;
174
175 struct kioctx *ki_ctx;
176 kiocb_cancel_fn *ki_cancel;
177
178 struct iocb __user *ki_user_iocb; /* user's aiocb */
179 __u64 ki_user_data; /* user's data for completion */
180
181 struct list_head ki_list; /* the aio core uses this
182 * for cancellation */
183
184 /*
185 * If the aio_resfd field of the userspace iocb is not zero,
186 * this is the underlying eventfd context to deliver events to.
187 */
188 struct eventfd_ctx *ki_eventfd;
189};
190
191/*------ sysctl variables----*/
192static DEFINE_SPINLOCK(aio_nr_lock);
193unsigned long aio_nr; /* current system wide number of aio requests */
194unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
195/*----end sysctl variables---*/
196
197static struct kmem_cache *kiocb_cachep;
198static struct kmem_cache *kioctx_cachep;
199
200static struct vfsmount *aio_mnt;
201
202static const struct file_operations aio_ring_fops;
203static const struct address_space_operations aio_ctx_aops;
204
205static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
206{
207 struct qstr this = QSTR_INIT("[aio]", 5);
208 struct file *file;
209 struct path path;
210 struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
211 if (IS_ERR(inode))
212 return ERR_CAST(inode);
213
214 inode->i_mapping->a_ops = &aio_ctx_aops;
215 inode->i_mapping->private_data = ctx;
216 inode->i_size = PAGE_SIZE * nr_pages;
217
218 path.dentry = d_alloc_pseudo(aio_mnt->mnt_sb, &this);
219 if (!path.dentry) {
220 iput(inode);
221 return ERR_PTR(-ENOMEM);
222 }
223 path.mnt = mntget(aio_mnt);
224
225 d_instantiate(path.dentry, inode);
226 file = alloc_file(&path, FMODE_READ | FMODE_WRITE, &aio_ring_fops);
227 if (IS_ERR(file)) {
228 path_put(&path);
229 return file;
230 }
231
232 file->f_flags = O_RDWR;
233 return file;
234}
235
236static struct dentry *aio_mount(struct file_system_type *fs_type,
237 int flags, const char *dev_name, void *data)
238{
239 static const struct dentry_operations ops = {
240 .d_dname = simple_dname,
241 };
242 return mount_pseudo(fs_type, "aio:", NULL, &ops, AIO_RING_MAGIC);
243}
244
245/* aio_setup
246 * Creates the slab caches used by the aio routines, panic on
247 * failure as this is done early during the boot sequence.
248 */
249static int __init aio_setup(void)
250{
251 static struct file_system_type aio_fs = {
252 .name = "aio",
253 .mount = aio_mount,
254 .kill_sb = kill_anon_super,
255 };
256 aio_mnt = kern_mount(&aio_fs);
257 if (IS_ERR(aio_mnt))
258 panic("Failed to create aio fs mount.");
259
260 kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
261 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
262
263 pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
264
265 return 0;
266}
267__initcall(aio_setup);
268
269static void put_aio_ring_file(struct kioctx *ctx)
270{
271 struct file *aio_ring_file = ctx->aio_ring_file;
272 if (aio_ring_file) {
273 truncate_setsize(aio_ring_file->f_inode, 0);
274
275 /* Prevent further access to the kioctx from migratepages */
276 spin_lock(&aio_ring_file->f_inode->i_mapping->private_lock);
277 aio_ring_file->f_inode->i_mapping->private_data = NULL;
278 ctx->aio_ring_file = NULL;
279 spin_unlock(&aio_ring_file->f_inode->i_mapping->private_lock);
280
281 fput(aio_ring_file);
282 }
283}
284
285static void aio_free_ring(struct kioctx *ctx)
286{
287 int i;
288
289 /* Disconnect the kiotx from the ring file. This prevents future
290 * accesses to the kioctx from page migration.
291 */
292 put_aio_ring_file(ctx);
293
294 for (i = 0; i < ctx->nr_pages; i++) {
295 struct page *page;
296 pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
297 page_count(ctx->ring_pages[i]));
298 page = ctx->ring_pages[i];
299 if (!page)
300 continue;
301 ctx->ring_pages[i] = NULL;
302 put_page(page);
303 }
304
305 if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
306 kfree(ctx->ring_pages);
307 ctx->ring_pages = NULL;
308 }
309}
310
311static int aio_ring_mremap(struct vm_area_struct *vma)
312{
313 struct file *file = vma->vm_file;
314 struct mm_struct *mm = vma->vm_mm;
315 struct kioctx_table *table;
316 int i, res = -EINVAL;
317
318 spin_lock(&mm->ioctx_lock);
319 rcu_read_lock();
320 table = rcu_dereference(mm->ioctx_table);
321 for (i = 0; i < table->nr; i++) {
322 struct kioctx *ctx;
323
324 ctx = table->table[i];
325 if (ctx && ctx->aio_ring_file == file) {
326 if (!atomic_read(&ctx->dead)) {
327 ctx->user_id = ctx->mmap_base = vma->vm_start;
328 res = 0;
329 }
330 break;
331 }
332 }
333
334 rcu_read_unlock();
335 spin_unlock(&mm->ioctx_lock);
336 return res;
337}
338
339static const struct vm_operations_struct aio_ring_vm_ops = {
340 .mremap = aio_ring_mremap,
341#if IS_ENABLED(CONFIG_MMU)
342 .fault = filemap_fault,
343 .map_pages = filemap_map_pages,
344 .page_mkwrite = filemap_page_mkwrite,
345#endif
346};
347
348static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
349{
350 vma->vm_flags |= VM_DONTEXPAND;
351 vma->vm_ops = &aio_ring_vm_ops;
352 return 0;
353}
354
355static const struct file_operations aio_ring_fops = {
356 .mmap = aio_ring_mmap,
357};
358
359#if IS_ENABLED(CONFIG_MIGRATION)
360static int aio_migratepage(struct address_space *mapping, struct page *new,
361 struct page *old, enum migrate_mode mode)
362{
363 struct kioctx *ctx;
364 unsigned long flags;
365 pgoff_t idx;
366 int rc;
367
368 rc = 0;
369
370 /* mapping->private_lock here protects against the kioctx teardown. */
371 spin_lock(&mapping->private_lock);
372 ctx = mapping->private_data;
373 if (!ctx) {
374 rc = -EINVAL;
375 goto out;
376 }
377
378 /* The ring_lock mutex. The prevents aio_read_events() from writing
379 * to the ring's head, and prevents page migration from mucking in
380 * a partially initialized kiotx.
381 */
382 if (!mutex_trylock(&ctx->ring_lock)) {
383 rc = -EAGAIN;
384 goto out;
385 }
386
387 idx = old->index;
388 if (idx < (pgoff_t)ctx->nr_pages) {
389 /* Make sure the old page hasn't already been changed */
390 if (ctx->ring_pages[idx] != old)
391 rc = -EAGAIN;
392 } else
393 rc = -EINVAL;
394
395 if (rc != 0)
396 goto out_unlock;
397
398 /* Writeback must be complete */
399 BUG_ON(PageWriteback(old));
400 get_page(new);
401
402 rc = migrate_page_move_mapping(mapping, new, old, NULL, mode, 1);
403 if (rc != MIGRATEPAGE_SUCCESS) {
404 put_page(new);
405 goto out_unlock;
406 }
407
408 /* Take completion_lock to prevent other writes to the ring buffer
409 * while the old page is copied to the new. This prevents new
410 * events from being lost.
411 */
412 spin_lock_irqsave(&ctx->completion_lock, flags);
413 migrate_page_copy(new, old);
414 BUG_ON(ctx->ring_pages[idx] != old);
415 ctx->ring_pages[idx] = new;
416 spin_unlock_irqrestore(&ctx->completion_lock, flags);
417
418 /* The old page is no longer accessible. */
419 put_page(old);
420
421out_unlock:
422 mutex_unlock(&ctx->ring_lock);
423out:
424 spin_unlock(&mapping->private_lock);
425 return rc;
426}
427#endif
428
429static const struct address_space_operations aio_ctx_aops = {
430 .set_page_dirty = __set_page_dirty_no_writeback,
431#if IS_ENABLED(CONFIG_MIGRATION)
432 .migratepage = aio_migratepage,
433#endif
434};
435
436static int aio_setup_ring(struct kioctx *ctx)
437{
438 struct aio_ring *ring;
439 unsigned nr_events = ctx->max_reqs;
440 struct mm_struct *mm = current->mm;
441 unsigned long size, unused;
442 int nr_pages;
443 int i;
444 struct file *file;
445
446 /* Compensate for the ring buffer's head/tail overlap entry */
447 nr_events += 2; /* 1 is required, 2 for good luck */
448
449 size = sizeof(struct aio_ring);
450 size += sizeof(struct io_event) * nr_events;
451
452 nr_pages = PFN_UP(size);
453 if (nr_pages < 0)
454 return -EINVAL;
455
456 file = aio_private_file(ctx, nr_pages);
457 if (IS_ERR(file)) {
458 ctx->aio_ring_file = NULL;
459 return -ENOMEM;
460 }
461
462 ctx->aio_ring_file = file;
463 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
464 / sizeof(struct io_event);
465
466 ctx->ring_pages = ctx->internal_pages;
467 if (nr_pages > AIO_RING_PAGES) {
468 ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
469 GFP_KERNEL);
470 if (!ctx->ring_pages) {
471 put_aio_ring_file(ctx);
472 return -ENOMEM;
473 }
474 }
475
476 for (i = 0; i < nr_pages; i++) {
477 struct page *page;
478 page = find_or_create_page(file->f_inode->i_mapping,
479 i, GFP_HIGHUSER | __GFP_ZERO);
480 if (!page)
481 break;
482 pr_debug("pid(%d) page[%d]->count=%d\n",
483 current->pid, i, page_count(page));
484 SetPageUptodate(page);
485 unlock_page(page);
486
487 ctx->ring_pages[i] = page;
488 }
489 ctx->nr_pages = i;
490
491 if (unlikely(i != nr_pages)) {
492 aio_free_ring(ctx);
493 return -ENOMEM;
494 }
495
496 ctx->mmap_size = nr_pages * PAGE_SIZE;
497 pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
498
499 down_write(&mm->mmap_sem);
500 ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size,
501 PROT_READ | PROT_WRITE,
502 MAP_SHARED, 0, &unused);
503 up_write(&mm->mmap_sem);
504 if (IS_ERR((void *)ctx->mmap_base)) {
505 ctx->mmap_size = 0;
506 aio_free_ring(ctx);
507 return -ENOMEM;
508 }
509
510 pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
511
512 ctx->user_id = ctx->mmap_base;
513 ctx->nr_events = nr_events; /* trusted copy */
514
515 ring = kmap_atomic(ctx->ring_pages[0]);
516 ring->nr = nr_events; /* user copy */
517 ring->id = ~0U;
518 ring->head = ring->tail = 0;
519 ring->magic = AIO_RING_MAGIC;
520 ring->compat_features = AIO_RING_COMPAT_FEATURES;
521 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
522 ring->header_length = sizeof(struct aio_ring);
523 kunmap_atomic(ring);
524 flush_dcache_page(ctx->ring_pages[0]);
525
526 return 0;
527}
528
529#define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
530#define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
531#define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
532
533void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
534{
535 struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, common);
536 struct kioctx *ctx = req->ki_ctx;
537 unsigned long flags;
538
539 spin_lock_irqsave(&ctx->ctx_lock, flags);
540
541 if (!req->ki_list.next)
542 list_add(&req->ki_list, &ctx->active_reqs);
543
544 req->ki_cancel = cancel;
545
546 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
547}
548EXPORT_SYMBOL(kiocb_set_cancel_fn);
549
550static int kiocb_cancel(struct aio_kiocb *kiocb)
551{
552 kiocb_cancel_fn *old, *cancel;
553
554 /*
555 * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
556 * actually has a cancel function, hence the cmpxchg()
557 */
558
559 cancel = ACCESS_ONCE(kiocb->ki_cancel);
560 do {
561 if (!cancel || cancel == KIOCB_CANCELLED)
562 return -EINVAL;
563
564 old = cancel;
565 cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
566 } while (cancel != old);
567
568 return cancel(&kiocb->common);
569}
570
571static void free_ioctx(struct work_struct *work)
572{
573 struct kioctx *ctx = container_of(work, struct kioctx, free_work);
574
575 pr_debug("freeing %p\n", ctx);
576
577 aio_free_ring(ctx);
578 free_percpu(ctx->cpu);
579 percpu_ref_exit(&ctx->reqs);
580 percpu_ref_exit(&ctx->users);
581 kmem_cache_free(kioctx_cachep, ctx);
582}
583
584static void free_ioctx_reqs(struct percpu_ref *ref)
585{
586 struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
587
588 /* At this point we know that there are no any in-flight requests */
589 if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
590 complete(&ctx->rq_wait->comp);
591
592 INIT_WORK(&ctx->free_work, free_ioctx);
593 schedule_work(&ctx->free_work);
594}
595
596/*
597 * When this function runs, the kioctx has been removed from the "hash table"
598 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
599 * now it's safe to cancel any that need to be.
600 */
601static void free_ioctx_users(struct percpu_ref *ref)
602{
603 struct kioctx *ctx = container_of(ref, struct kioctx, users);
604 struct aio_kiocb *req;
605
606 spin_lock_irq(&ctx->ctx_lock);
607
608 while (!list_empty(&ctx->active_reqs)) {
609 req = list_first_entry(&ctx->active_reqs,
610 struct aio_kiocb, ki_list);
611
612 list_del_init(&req->ki_list);
613 kiocb_cancel(req);
614 }
615
616 spin_unlock_irq(&ctx->ctx_lock);
617
618 percpu_ref_kill(&ctx->reqs);
619 percpu_ref_put(&ctx->reqs);
620}
621
622static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
623{
624 unsigned i, new_nr;
625 struct kioctx_table *table, *old;
626 struct aio_ring *ring;
627
628 spin_lock(&mm->ioctx_lock);
629 table = rcu_dereference_raw(mm->ioctx_table);
630
631 while (1) {
632 if (table)
633 for (i = 0; i < table->nr; i++)
634 if (!table->table[i]) {
635 ctx->id = i;
636 table->table[i] = ctx;
637 spin_unlock(&mm->ioctx_lock);
638
639 /* While kioctx setup is in progress,
640 * we are protected from page migration
641 * changes ring_pages by ->ring_lock.
642 */
643 ring = kmap_atomic(ctx->ring_pages[0]);
644 ring->id = ctx->id;
645 kunmap_atomic(ring);
646 return 0;
647 }
648
649 new_nr = (table ? table->nr : 1) * 4;
650 spin_unlock(&mm->ioctx_lock);
651
652 table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) *
653 new_nr, GFP_KERNEL);
654 if (!table)
655 return -ENOMEM;
656
657 table->nr = new_nr;
658
659 spin_lock(&mm->ioctx_lock);
660 old = rcu_dereference_raw(mm->ioctx_table);
661
662 if (!old) {
663 rcu_assign_pointer(mm->ioctx_table, table);
664 } else if (table->nr > old->nr) {
665 memcpy(table->table, old->table,
666 old->nr * sizeof(struct kioctx *));
667
668 rcu_assign_pointer(mm->ioctx_table, table);
669 kfree_rcu(old, rcu);
670 } else {
671 kfree(table);
672 table = old;
673 }
674 }
675}
676
677static void aio_nr_sub(unsigned nr)
678{
679 spin_lock(&aio_nr_lock);
680 if (WARN_ON(aio_nr - nr > aio_nr))
681 aio_nr = 0;
682 else
683 aio_nr -= nr;
684 spin_unlock(&aio_nr_lock);
685}
686
687/* ioctx_alloc
688 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
689 */
690static struct kioctx *ioctx_alloc(unsigned nr_events)
691{
692 struct mm_struct *mm = current->mm;
693 struct kioctx *ctx;
694 int err = -ENOMEM;
695
696 /*
697 * We keep track of the number of available ringbuffer slots, to prevent
698 * overflow (reqs_available), and we also use percpu counters for this.
699 *
700 * So since up to half the slots might be on other cpu's percpu counters
701 * and unavailable, double nr_events so userspace sees what they
702 * expected: additionally, we move req_batch slots to/from percpu
703 * counters at a time, so make sure that isn't 0:
704 */
705 nr_events = max(nr_events, num_possible_cpus() * 4);
706 nr_events *= 2;
707
708 /* Prevent overflows */
709 if (nr_events > (0x10000000U / sizeof(struct io_event))) {
710 pr_debug("ENOMEM: nr_events too high\n");
711 return ERR_PTR(-EINVAL);
712 }
713
714 if (!nr_events || (unsigned long)nr_events > (aio_max_nr * 2UL))
715 return ERR_PTR(-EAGAIN);
716
717 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
718 if (!ctx)
719 return ERR_PTR(-ENOMEM);
720
721 ctx->max_reqs = nr_events;
722
723 spin_lock_init(&ctx->ctx_lock);
724 spin_lock_init(&ctx->completion_lock);
725 mutex_init(&ctx->ring_lock);
726 /* Protect against page migration throughout kiotx setup by keeping
727 * the ring_lock mutex held until setup is complete. */
728 mutex_lock(&ctx->ring_lock);
729 init_waitqueue_head(&ctx->wait);
730
731 INIT_LIST_HEAD(&ctx->active_reqs);
732
733 if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL))
734 goto err;
735
736 if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL))
737 goto err;
738
739 ctx->cpu = alloc_percpu(struct kioctx_cpu);
740 if (!ctx->cpu)
741 goto err;
742
743 err = aio_setup_ring(ctx);
744 if (err < 0)
745 goto err;
746
747 atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
748 ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
749 if (ctx->req_batch < 1)
750 ctx->req_batch = 1;
751
752 /* limit the number of system wide aios */
753 spin_lock(&aio_nr_lock);
754 if (aio_nr + nr_events > (aio_max_nr * 2UL) ||
755 aio_nr + nr_events < aio_nr) {
756 spin_unlock(&aio_nr_lock);
757 err = -EAGAIN;
758 goto err_ctx;
759 }
760 aio_nr += ctx->max_reqs;
761 spin_unlock(&aio_nr_lock);
762
763 percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */
764 percpu_ref_get(&ctx->reqs); /* free_ioctx_users() will drop this */
765
766 err = ioctx_add_table(ctx, mm);
767 if (err)
768 goto err_cleanup;
769
770 /* Release the ring_lock mutex now that all setup is complete. */
771 mutex_unlock(&ctx->ring_lock);
772
773 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
774 ctx, ctx->user_id, mm, ctx->nr_events);
775 return ctx;
776
777err_cleanup:
778 aio_nr_sub(ctx->max_reqs);
779err_ctx:
780 atomic_set(&ctx->dead, 1);
781 if (ctx->mmap_size)
782 vm_munmap(ctx->mmap_base, ctx->mmap_size);
783 aio_free_ring(ctx);
784err:
785 mutex_unlock(&ctx->ring_lock);
786 free_percpu(ctx->cpu);
787 percpu_ref_exit(&ctx->reqs);
788 percpu_ref_exit(&ctx->users);
789 kmem_cache_free(kioctx_cachep, ctx);
790 pr_debug("error allocating ioctx %d\n", err);
791 return ERR_PTR(err);
792}
793
794/* kill_ioctx
795 * Cancels all outstanding aio requests on an aio context. Used
796 * when the processes owning a context have all exited to encourage
797 * the rapid destruction of the kioctx.
798 */
799static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
800 struct ctx_rq_wait *wait)
801{
802 struct kioctx_table *table;
803
804 spin_lock(&mm->ioctx_lock);
805 if (atomic_xchg(&ctx->dead, 1)) {
806 spin_unlock(&mm->ioctx_lock);
807 return -EINVAL;
808 }
809
810 table = rcu_dereference_raw(mm->ioctx_table);
811 WARN_ON(ctx != table->table[ctx->id]);
812 table->table[ctx->id] = NULL;
813 spin_unlock(&mm->ioctx_lock);
814
815 /* percpu_ref_kill() will do the necessary call_rcu() */
816 wake_up_all(&ctx->wait);
817
818 /*
819 * It'd be more correct to do this in free_ioctx(), after all
820 * the outstanding kiocbs have finished - but by then io_destroy
821 * has already returned, so io_setup() could potentially return
822 * -EAGAIN with no ioctxs actually in use (as far as userspace
823 * could tell).
824 */
825 aio_nr_sub(ctx->max_reqs);
826
827 if (ctx->mmap_size)
828 vm_munmap(ctx->mmap_base, ctx->mmap_size);
829
830 ctx->rq_wait = wait;
831 percpu_ref_kill(&ctx->users);
832 return 0;
833}
834
835/*
836 * exit_aio: called when the last user of mm goes away. At this point, there is
837 * no way for any new requests to be submited or any of the io_* syscalls to be
838 * called on the context.
839 *
840 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
841 * them.
842 */
843void exit_aio(struct mm_struct *mm)
844{
845 struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
846 struct ctx_rq_wait wait;
847 int i, skipped;
848
849 if (!table)
850 return;
851
852 atomic_set(&wait.count, table->nr);
853 init_completion(&wait.comp);
854
855 skipped = 0;
856 for (i = 0; i < table->nr; ++i) {
857 struct kioctx *ctx = table->table[i];
858
859 if (!ctx) {
860 skipped++;
861 continue;
862 }
863
864 /*
865 * We don't need to bother with munmap() here - exit_mmap(mm)
866 * is coming and it'll unmap everything. And we simply can't,
867 * this is not necessarily our ->mm.
868 * Since kill_ioctx() uses non-zero ->mmap_size as indicator
869 * that it needs to unmap the area, just set it to 0.
870 */
871 ctx->mmap_size = 0;
872 kill_ioctx(mm, ctx, &wait);
873 }
874
875 if (!atomic_sub_and_test(skipped, &wait.count)) {
876 /* Wait until all IO for the context are done. */
877 wait_for_completion(&wait.comp);
878 }
879
880 RCU_INIT_POINTER(mm->ioctx_table, NULL);
881 kfree(table);
882}
883
884static void put_reqs_available(struct kioctx *ctx, unsigned nr)
885{
886 struct kioctx_cpu *kcpu;
887 unsigned long flags;
888
889 local_irq_save(flags);
890 kcpu = this_cpu_ptr(ctx->cpu);
891 kcpu->reqs_available += nr;
892
893 while (kcpu->reqs_available >= ctx->req_batch * 2) {
894 kcpu->reqs_available -= ctx->req_batch;
895 atomic_add(ctx->req_batch, &ctx->reqs_available);
896 }
897
898 local_irq_restore(flags);
899}
900
901static bool get_reqs_available(struct kioctx *ctx)
902{
903 struct kioctx_cpu *kcpu;
904 bool ret = false;
905 unsigned long flags;
906
907 local_irq_save(flags);
908 kcpu = this_cpu_ptr(ctx->cpu);
909 if (!kcpu->reqs_available) {
910 int old, avail = atomic_read(&ctx->reqs_available);
911
912 do {
913 if (avail < ctx->req_batch)
914 goto out;
915
916 old = avail;
917 avail = atomic_cmpxchg(&ctx->reqs_available,
918 avail, avail - ctx->req_batch);
919 } while (avail != old);
920
921 kcpu->reqs_available += ctx->req_batch;
922 }
923
924 ret = true;
925 kcpu->reqs_available--;
926out:
927 local_irq_restore(flags);
928 return ret;
929}
930
931/* refill_reqs_available
932 * Updates the reqs_available reference counts used for tracking the
933 * number of free slots in the completion ring. This can be called
934 * from aio_complete() (to optimistically update reqs_available) or
935 * from aio_get_req() (the we're out of events case). It must be
936 * called holding ctx->completion_lock.
937 */
938static void refill_reqs_available(struct kioctx *ctx, unsigned head,
939 unsigned tail)
940{
941 unsigned events_in_ring, completed;
942
943 /* Clamp head since userland can write to it. */
944 head %= ctx->nr_events;
945 if (head <= tail)
946 events_in_ring = tail - head;
947 else
948 events_in_ring = ctx->nr_events - (head - tail);
949
950 completed = ctx->completed_events;
951 if (events_in_ring < completed)
952 completed -= events_in_ring;
953 else
954 completed = 0;
955
956 if (!completed)
957 return;
958
959 ctx->completed_events -= completed;
960 put_reqs_available(ctx, completed);
961}
962
963/* user_refill_reqs_available
964 * Called to refill reqs_available when aio_get_req() encounters an
965 * out of space in the completion ring.
966 */
967static void user_refill_reqs_available(struct kioctx *ctx)
968{
969 spin_lock_irq(&ctx->completion_lock);
970 if (ctx->completed_events) {
971 struct aio_ring *ring;
972 unsigned head;
973
974 /* Access of ring->head may race with aio_read_events_ring()
975 * here, but that's okay since whether we read the old version
976 * or the new version, and either will be valid. The important
977 * part is that head cannot pass tail since we prevent
978 * aio_complete() from updating tail by holding
979 * ctx->completion_lock. Even if head is invalid, the check
980 * against ctx->completed_events below will make sure we do the
981 * safe/right thing.
982 */
983 ring = kmap_atomic(ctx->ring_pages[0]);
984 head = ring->head;
985 kunmap_atomic(ring);
986
987 refill_reqs_available(ctx, head, ctx->tail);
988 }
989
990 spin_unlock_irq(&ctx->completion_lock);
991}
992
993/* aio_get_req
994 * Allocate a slot for an aio request.
995 * Returns NULL if no requests are free.
996 */
997static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
998{
999 struct aio_kiocb *req;
1000
1001 if (!get_reqs_available(ctx)) {
1002 user_refill_reqs_available(ctx);
1003 if (!get_reqs_available(ctx))
1004 return NULL;
1005 }
1006
1007 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
1008 if (unlikely(!req))
1009 goto out_put;
1010
1011 percpu_ref_get(&ctx->reqs);
1012
1013 req->ki_ctx = ctx;
1014 return req;
1015out_put:
1016 put_reqs_available(ctx, 1);
1017 return NULL;
1018}
1019
1020static void kiocb_free(struct aio_kiocb *req)
1021{
1022 if (req->common.ki_filp)
1023 fput(req->common.ki_filp);
1024 if (req->ki_eventfd != NULL)
1025 eventfd_ctx_put(req->ki_eventfd);
1026 kmem_cache_free(kiocb_cachep, req);
1027}
1028
1029static struct kioctx *lookup_ioctx(unsigned long ctx_id)
1030{
1031 struct aio_ring __user *ring = (void __user *)ctx_id;
1032 struct mm_struct *mm = current->mm;
1033 struct kioctx *ctx, *ret = NULL;
1034 struct kioctx_table *table;
1035 unsigned id;
1036
1037 if (get_user(id, &ring->id))
1038 return NULL;
1039
1040 rcu_read_lock();
1041 table = rcu_dereference(mm->ioctx_table);
1042
1043 if (!table || id >= table->nr)
1044 goto out;
1045
1046 ctx = table->table[id];
1047 if (ctx && ctx->user_id == ctx_id) {
1048 percpu_ref_get(&ctx->users);
1049 ret = ctx;
1050 }
1051out:
1052 rcu_read_unlock();
1053 return ret;
1054}
1055
1056/* aio_complete
1057 * Called when the io request on the given iocb is complete.
1058 */
1059static void aio_complete(struct kiocb *kiocb, long res, long res2)
1060{
1061 struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, common);
1062 struct kioctx *ctx = iocb->ki_ctx;
1063 struct aio_ring *ring;
1064 struct io_event *ev_page, *event;
1065 unsigned tail, pos, head;
1066 unsigned long flags;
1067
1068 /*
1069 * Special case handling for sync iocbs:
1070 * - events go directly into the iocb for fast handling
1071 * - the sync task with the iocb in its stack holds the single iocb
1072 * ref, no other paths have a way to get another ref
1073 * - the sync task helpfully left a reference to itself in the iocb
1074 */
1075 BUG_ON(is_sync_kiocb(kiocb));
1076
1077 if (iocb->ki_list.next) {
1078 unsigned long flags;
1079
1080 spin_lock_irqsave(&ctx->ctx_lock, flags);
1081 list_del(&iocb->ki_list);
1082 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1083 }
1084
1085 /*
1086 * Add a completion event to the ring buffer. Must be done holding
1087 * ctx->completion_lock to prevent other code from messing with the tail
1088 * pointer since we might be called from irq context.
1089 */
1090 spin_lock_irqsave(&ctx->completion_lock, flags);
1091
1092 tail = ctx->tail;
1093 pos = tail + AIO_EVENTS_OFFSET;
1094
1095 if (++tail >= ctx->nr_events)
1096 tail = 0;
1097
1098 ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1099 event = ev_page + pos % AIO_EVENTS_PER_PAGE;
1100
1101 event->obj = (u64)(unsigned long)iocb->ki_user_iocb;
1102 event->data = iocb->ki_user_data;
1103 event->res = res;
1104 event->res2 = res2;
1105
1106 kunmap_atomic(ev_page);
1107 flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1108
1109 pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
1110 ctx, tail, iocb, iocb->ki_user_iocb, iocb->ki_user_data,
1111 res, res2);
1112
1113 /* after flagging the request as done, we
1114 * must never even look at it again
1115 */
1116 smp_wmb(); /* make event visible before updating tail */
1117
1118 ctx->tail = tail;
1119
1120 ring = kmap_atomic(ctx->ring_pages[0]);
1121 head = ring->head;
1122 ring->tail = tail;
1123 kunmap_atomic(ring);
1124 flush_dcache_page(ctx->ring_pages[0]);
1125
1126 ctx->completed_events++;
1127 if (ctx->completed_events > 1)
1128 refill_reqs_available(ctx, head, tail);
1129 spin_unlock_irqrestore(&ctx->completion_lock, flags);
1130
1131 pr_debug("added to ring %p at [%u]\n", iocb, tail);
1132
1133 /*
1134 * Check if the user asked us to deliver the result through an
1135 * eventfd. The eventfd_signal() function is safe to be called
1136 * from IRQ context.
1137 */
1138 if (iocb->ki_eventfd != NULL)
1139 eventfd_signal(iocb->ki_eventfd, 1);
1140
1141 /* everything turned out well, dispose of the aiocb. */
1142 kiocb_free(iocb);
1143
1144 /*
1145 * We have to order our ring_info tail store above and test
1146 * of the wait list below outside the wait lock. This is
1147 * like in wake_up_bit() where clearing a bit has to be
1148 * ordered with the unlocked test.
1149 */
1150 smp_mb();
1151
1152 if (waitqueue_active(&ctx->wait))
1153 wake_up(&ctx->wait);
1154
1155 percpu_ref_put(&ctx->reqs);
1156}
1157
1158/* aio_read_events_ring
1159 * Pull an event off of the ioctx's event ring. Returns the number of
1160 * events fetched
1161 */
1162static long aio_read_events_ring(struct kioctx *ctx,
1163 struct io_event __user *event, long nr)
1164{
1165 struct aio_ring *ring;
1166 unsigned head, tail, pos;
1167 long ret = 0;
1168 int copy_ret;
1169
1170 /*
1171 * The mutex can block and wake us up and that will cause
1172 * wait_event_interruptible_hrtimeout() to schedule without sleeping
1173 * and repeat. This should be rare enough that it doesn't cause
1174 * peformance issues. See the comment in read_events() for more detail.
1175 */
1176 sched_annotate_sleep();
1177 mutex_lock(&ctx->ring_lock);
1178
1179 /* Access to ->ring_pages here is protected by ctx->ring_lock. */
1180 ring = kmap_atomic(ctx->ring_pages[0]);
1181 head = ring->head;
1182 tail = ring->tail;
1183 kunmap_atomic(ring);
1184
1185 /*
1186 * Ensure that once we've read the current tail pointer, that
1187 * we also see the events that were stored up to the tail.
1188 */
1189 smp_rmb();
1190
1191 pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
1192
1193 if (head == tail)
1194 goto out;
1195
1196 head %= ctx->nr_events;
1197 tail %= ctx->nr_events;
1198
1199 while (ret < nr) {
1200 long avail;
1201 struct io_event *ev;
1202 struct page *page;
1203
1204 avail = (head <= tail ? tail : ctx->nr_events) - head;
1205 if (head == tail)
1206 break;
1207
1208 avail = min(avail, nr - ret);
1209 avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
1210 ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
1211
1212 pos = head + AIO_EVENTS_OFFSET;
1213 page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
1214 pos %= AIO_EVENTS_PER_PAGE;
1215
1216 ev = kmap(page);
1217 copy_ret = copy_to_user(event + ret, ev + pos,
1218 sizeof(*ev) * avail);
1219 kunmap(page);
1220
1221 if (unlikely(copy_ret)) {
1222 ret = -EFAULT;
1223 goto out;
1224 }
1225
1226 ret += avail;
1227 head += avail;
1228 head %= ctx->nr_events;
1229 }
1230
1231 ring = kmap_atomic(ctx->ring_pages[0]);
1232 ring->head = head;
1233 kunmap_atomic(ring);
1234 flush_dcache_page(ctx->ring_pages[0]);
1235
1236 pr_debug("%li h%u t%u\n", ret, head, tail);
1237out:
1238 mutex_unlock(&ctx->ring_lock);
1239
1240 return ret;
1241}
1242
1243static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
1244 struct io_event __user *event, long *i)
1245{
1246 long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
1247
1248 if (ret > 0)
1249 *i += ret;
1250
1251 if (unlikely(atomic_read(&ctx->dead)))
1252 ret = -EINVAL;
1253
1254 if (!*i)
1255 *i = ret;
1256
1257 return ret < 0 || *i >= min_nr;
1258}
1259
1260static long read_events(struct kioctx *ctx, long min_nr, long nr,
1261 struct io_event __user *event,
1262 struct timespec __user *timeout)
1263{
1264 ktime_t until = { .tv64 = KTIME_MAX };
1265 long ret = 0;
1266
1267 if (timeout) {
1268 struct timespec ts;
1269
1270 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
1271 return -EFAULT;
1272
1273 until = timespec_to_ktime(ts);
1274 }
1275
1276 /*
1277 * Note that aio_read_events() is being called as the conditional - i.e.
1278 * we're calling it after prepare_to_wait() has set task state to
1279 * TASK_INTERRUPTIBLE.
1280 *
1281 * But aio_read_events() can block, and if it blocks it's going to flip
1282 * the task state back to TASK_RUNNING.
1283 *
1284 * This should be ok, provided it doesn't flip the state back to
1285 * TASK_RUNNING and return 0 too much - that causes us to spin. That
1286 * will only happen if the mutex_lock() call blocks, and we then find
1287 * the ringbuffer empty. So in practice we should be ok, but it's
1288 * something to be aware of when touching this code.
1289 */
1290 if (until.tv64 == 0)
1291 aio_read_events(ctx, min_nr, nr, event, &ret);
1292 else
1293 wait_event_interruptible_hrtimeout(ctx->wait,
1294 aio_read_events(ctx, min_nr, nr, event, &ret),
1295 until);
1296
1297 if (!ret && signal_pending(current))
1298 ret = -EINTR;
1299
1300 return ret;
1301}
1302
1303/* sys_io_setup:
1304 * Create an aio_context capable of receiving at least nr_events.
1305 * ctxp must not point to an aio_context that already exists, and
1306 * must be initialized to 0 prior to the call. On successful
1307 * creation of the aio_context, *ctxp is filled in with the resulting
1308 * handle. May fail with -EINVAL if *ctxp is not initialized,
1309 * if the specified nr_events exceeds internal limits. May fail
1310 * with -EAGAIN if the specified nr_events exceeds the user's limit
1311 * of available events. May fail with -ENOMEM if insufficient kernel
1312 * resources are available. May fail with -EFAULT if an invalid
1313 * pointer is passed for ctxp. Will fail with -ENOSYS if not
1314 * implemented.
1315 */
1316SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1317{
1318 struct kioctx *ioctx = NULL;
1319 unsigned long ctx;
1320 long ret;
1321
1322 ret = get_user(ctx, ctxp);
1323 if (unlikely(ret))
1324 goto out;
1325
1326 ret = -EINVAL;
1327 if (unlikely(ctx || nr_events == 0)) {
1328 pr_debug("EINVAL: ctx %lu nr_events %u\n",
1329 ctx, nr_events);
1330 goto out;
1331 }
1332
1333 ioctx = ioctx_alloc(nr_events);
1334 ret = PTR_ERR(ioctx);
1335 if (!IS_ERR(ioctx)) {
1336 ret = put_user(ioctx->user_id, ctxp);
1337 if (ret)
1338 kill_ioctx(current->mm, ioctx, NULL);
1339 percpu_ref_put(&ioctx->users);
1340 }
1341
1342out:
1343 return ret;
1344}
1345
1346/* sys_io_destroy:
1347 * Destroy the aio_context specified. May cancel any outstanding
1348 * AIOs and block on completion. Will fail with -ENOSYS if not
1349 * implemented. May fail with -EINVAL if the context pointed to
1350 * is invalid.
1351 */
1352SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1353{
1354 struct kioctx *ioctx = lookup_ioctx(ctx);
1355 if (likely(NULL != ioctx)) {
1356 struct ctx_rq_wait wait;
1357 int ret;
1358
1359 init_completion(&wait.comp);
1360 atomic_set(&wait.count, 1);
1361
1362 /* Pass requests_done to kill_ioctx() where it can be set
1363 * in a thread-safe way. If we try to set it here then we have
1364 * a race condition if two io_destroy() called simultaneously.
1365 */
1366 ret = kill_ioctx(current->mm, ioctx, &wait);
1367 percpu_ref_put(&ioctx->users);
1368
1369 /* Wait until all IO for the context are done. Otherwise kernel
1370 * keep using user-space buffers even if user thinks the context
1371 * is destroyed.
1372 */
1373 if (!ret)
1374 wait_for_completion(&wait.comp);
1375
1376 return ret;
1377 }
1378 pr_debug("EINVAL: invalid context id\n");
1379 return -EINVAL;
1380}
1381
1382typedef ssize_t (rw_iter_op)(struct kiocb *, struct iov_iter *);
1383
1384static int aio_setup_vectored_rw(int rw, char __user *buf, size_t len,
1385 struct iovec **iovec,
1386 bool compat,
1387 struct iov_iter *iter)
1388{
1389#ifdef CONFIG_COMPAT
1390 if (compat)
1391 return compat_import_iovec(rw,
1392 (struct compat_iovec __user *)buf,
1393 len, UIO_FASTIOV, iovec, iter);
1394#endif
1395 return import_iovec(rw, (struct iovec __user *)buf,
1396 len, UIO_FASTIOV, iovec, iter);
1397}
1398
1399/*
1400 * aio_run_iocb:
1401 * Performs the initial checks and io submission.
1402 */
1403static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
1404 char __user *buf, size_t len, bool compat)
1405{
1406 struct file *file = req->ki_filp;
1407 ssize_t ret;
1408 int rw;
1409 fmode_t mode;
1410 rw_iter_op *iter_op;
1411 struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1412 struct iov_iter iter;
1413
1414 switch (opcode) {
1415 case IOCB_CMD_PREAD:
1416 case IOCB_CMD_PREADV:
1417 mode = FMODE_READ;
1418 rw = READ;
1419 iter_op = file->f_op->read_iter;
1420 goto rw_common;
1421
1422 case IOCB_CMD_PWRITE:
1423 case IOCB_CMD_PWRITEV:
1424 mode = FMODE_WRITE;
1425 rw = WRITE;
1426 iter_op = file->f_op->write_iter;
1427 goto rw_common;
1428rw_common:
1429 if (unlikely(!(file->f_mode & mode)))
1430 return -EBADF;
1431
1432 if (!iter_op)
1433 return -EINVAL;
1434
1435 if (opcode == IOCB_CMD_PREADV || opcode == IOCB_CMD_PWRITEV)
1436 ret = aio_setup_vectored_rw(rw, buf, len,
1437 &iovec, compat, &iter);
1438 else {
1439 ret = import_single_range(rw, buf, len, iovec, &iter);
1440 iovec = NULL;
1441 }
1442 if (!ret)
1443 ret = rw_verify_area(rw, file, &req->ki_pos,
1444 iov_iter_count(&iter));
1445 if (ret < 0) {
1446 kfree(iovec);
1447 return ret;
1448 }
1449
1450 len = ret;
1451
1452 if (rw == WRITE)
1453 file_start_write(file);
1454
1455 ret = iter_op(req, &iter);
1456
1457 if (rw == WRITE)
1458 file_end_write(file);
1459 kfree(iovec);
1460 break;
1461
1462 case IOCB_CMD_FDSYNC:
1463 if (!file->f_op->aio_fsync)
1464 return -EINVAL;
1465
1466 ret = file->f_op->aio_fsync(req, 1);
1467 break;
1468
1469 case IOCB_CMD_FSYNC:
1470 if (!file->f_op->aio_fsync)
1471 return -EINVAL;
1472
1473 ret = file->f_op->aio_fsync(req, 0);
1474 break;
1475
1476 default:
1477 pr_debug("EINVAL: no operation provided\n");
1478 return -EINVAL;
1479 }
1480
1481 if (ret != -EIOCBQUEUED) {
1482 /*
1483 * There's no easy way to restart the syscall since other AIO's
1484 * may be already running. Just fail this IO with EINTR.
1485 */
1486 if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
1487 ret == -ERESTARTNOHAND ||
1488 ret == -ERESTART_RESTARTBLOCK))
1489 ret = -EINTR;
1490 aio_complete(req, ret, 0);
1491 }
1492
1493 return 0;
1494}
1495
1496static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1497 struct iocb *iocb, bool compat)
1498{
1499 struct aio_kiocb *req;
1500 ssize_t ret;
1501
1502 /* enforce forwards compatibility on users */
1503 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
1504 pr_debug("EINVAL: reserve field set\n");
1505 return -EINVAL;
1506 }
1507
1508 /* prevent overflows */
1509 if (unlikely(
1510 (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
1511 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
1512 ((ssize_t)iocb->aio_nbytes < 0)
1513 )) {
1514 pr_debug("EINVAL: overflow check\n");
1515 return -EINVAL;
1516 }
1517
1518 req = aio_get_req(ctx);
1519 if (unlikely(!req))
1520 return -EAGAIN;
1521
1522 req->common.ki_filp = fget(iocb->aio_fildes);
1523 if (unlikely(!req->common.ki_filp)) {
1524 ret = -EBADF;
1525 goto out_put_req;
1526 }
1527 req->common.ki_pos = iocb->aio_offset;
1528 req->common.ki_complete = aio_complete;
1529 req->common.ki_flags = iocb_flags(req->common.ki_filp);
1530
1531 if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1532 /*
1533 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1534 * instance of the file* now. The file descriptor must be
1535 * an eventfd() fd, and will be signaled for each completed
1536 * event using the eventfd_signal() function.
1537 */
1538 req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
1539 if (IS_ERR(req->ki_eventfd)) {
1540 ret = PTR_ERR(req->ki_eventfd);
1541 req->ki_eventfd = NULL;
1542 goto out_put_req;
1543 }
1544
1545 req->common.ki_flags |= IOCB_EVENTFD;
1546 }
1547
1548 ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
1549 if (unlikely(ret)) {
1550 pr_debug("EFAULT: aio_key\n");
1551 goto out_put_req;
1552 }
1553
1554 req->ki_user_iocb = user_iocb;
1555 req->ki_user_data = iocb->aio_data;
1556
1557 ret = aio_run_iocb(&req->common, iocb->aio_lio_opcode,
1558 (char __user *)(unsigned long)iocb->aio_buf,
1559 iocb->aio_nbytes,
1560 compat);
1561 if (ret)
1562 goto out_put_req;
1563
1564 return 0;
1565out_put_req:
1566 put_reqs_available(ctx, 1);
1567 percpu_ref_put(&ctx->reqs);
1568 kiocb_free(req);
1569 return ret;
1570}
1571
1572long do_io_submit(aio_context_t ctx_id, long nr,
1573 struct iocb __user *__user *iocbpp, bool compat)
1574{
1575 struct kioctx *ctx;
1576 long ret = 0;
1577 int i = 0;
1578 struct blk_plug plug;
1579
1580 if (unlikely(nr < 0))
1581 return -EINVAL;
1582
1583 if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
1584 nr = LONG_MAX/sizeof(*iocbpp);
1585
1586 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1587 return -EFAULT;
1588
1589 ctx = lookup_ioctx(ctx_id);
1590 if (unlikely(!ctx)) {
1591 pr_debug("EINVAL: invalid context id\n");
1592 return -EINVAL;
1593 }
1594
1595 blk_start_plug(&plug);
1596
1597 /*
1598 * AKPM: should this return a partial result if some of the IOs were
1599 * successfully submitted?
1600 */
1601 for (i=0; i<nr; i++) {
1602 struct iocb __user *user_iocb;
1603 struct iocb tmp;
1604
1605 if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1606 ret = -EFAULT;
1607 break;
1608 }
1609
1610 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1611 ret = -EFAULT;
1612 break;
1613 }
1614
1615 ret = io_submit_one(ctx, user_iocb, &tmp, compat);
1616 if (ret)
1617 break;
1618 }
1619 blk_finish_plug(&plug);
1620
1621 percpu_ref_put(&ctx->users);
1622 return i ? i : ret;
1623}
1624
1625/* sys_io_submit:
1626 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1627 * the number of iocbs queued. May return -EINVAL if the aio_context
1628 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1629 * *iocbpp[0] is not properly initialized, if the operation specified
1630 * is invalid for the file descriptor in the iocb. May fail with
1631 * -EFAULT if any of the data structures point to invalid data. May
1632 * fail with -EBADF if the file descriptor specified in the first
1633 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1634 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1635 * fail with -ENOSYS if not implemented.
1636 */
1637SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
1638 struct iocb __user * __user *, iocbpp)
1639{
1640 return do_io_submit(ctx_id, nr, iocbpp, 0);
1641}
1642
1643/* lookup_kiocb
1644 * Finds a given iocb for cancellation.
1645 */
1646static struct aio_kiocb *
1647lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, u32 key)
1648{
1649 struct aio_kiocb *kiocb;
1650
1651 assert_spin_locked(&ctx->ctx_lock);
1652
1653 if (key != KIOCB_KEY)
1654 return NULL;
1655
1656 /* TODO: use a hash or array, this sucks. */
1657 list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
1658 if (kiocb->ki_user_iocb == iocb)
1659 return kiocb;
1660 }
1661 return NULL;
1662}
1663
1664/* sys_io_cancel:
1665 * Attempts to cancel an iocb previously passed to io_submit. If
1666 * the operation is successfully cancelled, the resulting event is
1667 * copied into the memory pointed to by result without being placed
1668 * into the completion queue and 0 is returned. May fail with
1669 * -EFAULT if any of the data structures pointed to are invalid.
1670 * May fail with -EINVAL if aio_context specified by ctx_id is
1671 * invalid. May fail with -EAGAIN if the iocb specified was not
1672 * cancelled. Will fail with -ENOSYS if not implemented.
1673 */
1674SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
1675 struct io_event __user *, result)
1676{
1677 struct kioctx *ctx;
1678 struct aio_kiocb *kiocb;
1679 u32 key;
1680 int ret;
1681
1682 ret = get_user(key, &iocb->aio_key);
1683 if (unlikely(ret))
1684 return -EFAULT;
1685
1686 ctx = lookup_ioctx(ctx_id);
1687 if (unlikely(!ctx))
1688 return -EINVAL;
1689
1690 spin_lock_irq(&ctx->ctx_lock);
1691
1692 kiocb = lookup_kiocb(ctx, iocb, key);
1693 if (kiocb)
1694 ret = kiocb_cancel(kiocb);
1695 else
1696 ret = -EINVAL;
1697
1698 spin_unlock_irq(&ctx->ctx_lock);
1699
1700 if (!ret) {
1701 /*
1702 * The result argument is no longer used - the io_event is
1703 * always delivered via the ring buffer. -EINPROGRESS indicates
1704 * cancellation is progress:
1705 */
1706 ret = -EINPROGRESS;
1707 }
1708
1709 percpu_ref_put(&ctx->users);
1710
1711 return ret;
1712}
1713
1714/* io_getevents:
1715 * Attempts to read at least min_nr events and up to nr events from
1716 * the completion queue for the aio_context specified by ctx_id. If
1717 * it succeeds, the number of read events is returned. May fail with
1718 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
1719 * out of range, if timeout is out of range. May fail with -EFAULT
1720 * if any of the memory specified is invalid. May return 0 or
1721 * < min_nr if the timeout specified by timeout has elapsed
1722 * before sufficient events are available, where timeout == NULL
1723 * specifies an infinite timeout. Note that the timeout pointed to by
1724 * timeout is relative. Will fail with -ENOSYS if not implemented.
1725 */
1726SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
1727 long, min_nr,
1728 long, nr,
1729 struct io_event __user *, events,
1730 struct timespec __user *, timeout)
1731{
1732 struct kioctx *ioctx = lookup_ioctx(ctx_id);
1733 long ret = -EINVAL;
1734
1735 if (likely(ioctx)) {
1736 if (likely(min_nr <= nr && min_nr >= 0))
1737 ret = read_events(ioctx, min_nr, nr, events, timeout);
1738 percpu_ref_put(&ioctx->users);
1739 }
1740 return ret;
1741}