1 /*
2 * An async IO implementation for Linux
3 * Written by Benjamin LaHaise <bcrl@kvack.org>
4 *
5 * Implements an efficient asynchronous io interface.
6 *
7 * Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved.
8 * Copyright 2018 Christoph Hellwig.
9 *
10 * See ../COPYING for licensing terms.
11 */
12 #define pr_fmt(fmt) "%s: " fmt, __func__
13
14 #include <linux/kernel.h>
15 #include <linux/init.h>
16 #include <linux/errno.h>
17 #include <linux/time.h>
18 #include <linux/aio_abi.h>
19 #include <linux/export.h>
20 #include <linux/syscalls.h>
21 #include <linux/backing-dev.h>
22 #include <linux/refcount.h>
23 #include <linux/uio.h>
24
25 #include <linux/sched/signal.h>
26 #include <linux/fs.h>
27 #include <linux/file.h>
28 #include <linux/mm.h>
29 #include <linux/mman.h>
30 #include <linux/percpu.h>
31 #include <linux/slab.h>
32 #include <linux/timer.h>
33 #include <linux/aio.h>
34 #include <linux/highmem.h>
35 #include <linux/workqueue.h>
36 #include <linux/security.h>
37 #include <linux/eventfd.h>
38 #include <linux/blkdev.h>
39 #include <linux/compat.h>
40 #include <linux/migrate.h>
41 #include <linux/ramfs.h>
42 #include <linux/percpu-refcount.h>
43 #include <linux/mount.h>
44 #include <linux/pseudo_fs.h>
45
46 #include <linux/uaccess.h>
47 #include <linux/nospec.h>
48
49 #include "internal.h"
50
51 #define KIOCB_KEY 0
52
53 #define AIO_RING_MAGIC 0xa10a10a1
54 #define AIO_RING_COMPAT_FEATURES 1
55 #define AIO_RING_INCOMPAT_FEATURES 0
56 struct aio_ring {
57 unsigned id; /* kernel internal index number */
58 unsigned nr; /* number of io_events */
59 unsigned head; /* Written to by userland or under ring_lock
60 * mutex by aio_read_events_ring(). */
61 unsigned tail;
62
63 unsigned magic;
64 unsigned compat_features;
65 unsigned incompat_features;
66 unsigned header_length; /* size of aio_ring */
67
68
69 struct io_event io_events[];
70 }; /* 128 bytes + ring size */
71
72 /*
73 * Plugging is meant to work with larger batches of IOs. If we don't
74 * have more than the below, then don't bother setting up a plug.
75 */
76 #define AIO_PLUG_THRESHOLD 2
77
78 #define AIO_RING_PAGES 8
79
80 struct kioctx_table {
81 struct rcu_head rcu;
82 unsigned nr;
83 struct kioctx __rcu *table[] __counted_by(nr);
84 };
85
86 struct kioctx_cpu {
87 unsigned reqs_available;
88 };
89
90 struct ctx_rq_wait {
91 struct completion comp;
92 atomic_t count;
93 };
94
95 struct kioctx {
96 struct percpu_ref users;
97 atomic_t dead;
98
99 struct percpu_ref reqs;
100
101 unsigned long user_id;
102
103 struct __percpu kioctx_cpu *cpu;
104
105 /*
106 * For percpu reqs_available, number of slots we move to/from global
107 * counter at a time:
108 */
109 unsigned req_batch;
110 /*
111 * This is what userspace passed to io_setup(), it's not used for
112 * anything but counting against the global max_reqs quota.
113 *
114 * The real limit is nr_events - 1, which will be larger (see
115 * aio_setup_ring())
116 */
117 unsigned max_reqs;
118
119 /* Size of ringbuffer, in units of struct io_event */
120 unsigned nr_events;
121
122 unsigned long mmap_base;
123 unsigned long mmap_size;
124
125 struct folio **ring_folios;
126 long nr_pages;
127
128 struct rcu_work free_rwork; /* see free_ioctx() */
129
130 /*
131 * signals when all in-flight requests are done
132 */
133 struct ctx_rq_wait *rq_wait;
134
135 struct {
136 /*
137 * This counts the number of available slots in the ringbuffer,
138 * so we avoid overflowing it: it's decremented (if positive)
139 * when allocating a kiocb and incremented when the resulting
140 * io_event is pulled off the ringbuffer.
141 *
142 * We batch accesses to it with a percpu version.
143 */
144 atomic_t reqs_available;
145 } ____cacheline_aligned_in_smp;
146
147 struct {
148 spinlock_t ctx_lock;
149 struct list_head active_reqs; /* used for cancellation */
150 } ____cacheline_aligned_in_smp;
151
152 struct {
153 struct mutex ring_lock;
154 wait_queue_head_t wait;
155 } ____cacheline_aligned_in_smp;
156
157 struct {
158 unsigned tail;
159 unsigned completed_events;
160 spinlock_t completion_lock;
161 } ____cacheline_aligned_in_smp;
162
163 struct folio *internal_folios[AIO_RING_PAGES];
164 struct file *aio_ring_file;
165
166 unsigned id;
167 };
168
169 /*
170 * First field must be the file pointer in all the
171 * iocb unions! See also 'struct kiocb' in <linux/fs.h>
172 */
173 struct fsync_iocb {
174 struct file *file;
175 struct work_struct work;
176 bool datasync;
177 struct cred *creds;
178 };
179
180 struct poll_iocb {
181 struct file *file;
182 struct wait_queue_head *head;
183 __poll_t events;
184 bool cancelled;
185 bool work_scheduled;
186 bool work_need_resched;
187 struct wait_queue_entry wait;
188 struct work_struct work;
189 };
190
191 /*
192 * NOTE! Each of the iocb union members has the file pointer
193 * as the first entry in their struct definition. So you can
194 * access the file pointer through any of the sub-structs,
195 * or directly as just 'ki_filp' in this struct.
196 */
197 struct aio_kiocb {
198 union {
199 struct file *ki_filp;
200 struct kiocb rw;
201 struct fsync_iocb fsync;
202 struct poll_iocb poll;
203 };
204
205 struct kioctx *ki_ctx;
206 kiocb_cancel_fn *ki_cancel;
207
208 struct io_event ki_res;
209
210 struct list_head ki_list; /* the aio core uses this
211 * for cancellation */
212 refcount_t ki_refcnt;
213
214 /*
215 * If the aio_resfd field of the userspace iocb is not zero,
216 * this is the underlying eventfd context to deliver events to.
217 */
218 struct eventfd_ctx *ki_eventfd;
219 };
220
221 /*------ sysctl variables----*/
222 static DEFINE_SPINLOCK(aio_nr_lock);
223 static unsigned long aio_nr; /* current system wide number of aio requests */
224 static unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
225 /*----end sysctl variables---*/
226 #ifdef CONFIG_SYSCTL
227 static struct ctl_table aio_sysctls[] = {
228 {
229 .procname = "aio-nr",
230 .data = &aio_nr,
231 .maxlen = sizeof(aio_nr),
232 .mode = 0444,
233 .proc_handler = proc_doulongvec_minmax,
234 },
235 {
236 .procname = "aio-max-nr",
237 .data = &aio_max_nr,
238 .maxlen = sizeof(aio_max_nr),
239 .mode = 0644,
240 .proc_handler = proc_doulongvec_minmax,
241 },
242 };
243
244 static void __init aio_sysctl_init(void)
245 {
246 register_sysctl_init("fs", aio_sysctls);
247 }
248 #else
249 #define aio_sysctl_init() do { } while (0)
250 #endif
251
252 static struct kmem_cache *kiocb_cachep;
253 static struct kmem_cache *kioctx_cachep;
254
255 static struct vfsmount *aio_mnt;
256
257 static const struct file_operations aio_ring_fops;
258 static const struct address_space_operations aio_ctx_aops;
259
260 static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
261 {
262 struct file *file;
263 struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
264 if (IS_ERR(inode))
265 return ERR_CAST(inode);
266
267 inode->i_mapping->a_ops = &aio_ctx_aops;
268 inode->i_mapping->i_private_data = ctx;
269 inode->i_size = PAGE_SIZE * nr_pages;
270
271 file = alloc_file_pseudo(inode, aio_mnt, "[aio]",
272 O_RDWR, &aio_ring_fops);
273 if (IS_ERR(file))
274 iput(inode);
275 return file;
276 }
277
278 static int aio_init_fs_context(struct fs_context *fc)
279 {
280 if (!init_pseudo(fc, AIO_RING_MAGIC))
281 return -ENOMEM;
282 fc->s_iflags |= SB_I_NOEXEC;
283 return 0;
284 }
285
286 /* aio_setup
287 * Creates the slab caches used by the aio routines, panic on
288 * failure as this is done early during the boot sequence.
289 */
290 static int __init aio_setup(void)
291 {
292 static struct file_system_type aio_fs = {
293 .name = "aio",
294 .init_fs_context = aio_init_fs_context,
295 .kill_sb = kill_anon_super,
296 };
297 aio_mnt = kern_mount(&aio_fs);
298 if (IS_ERR(aio_mnt))
299 panic("Failed to create aio fs mount.");
300
301 kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
302 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
303 aio_sysctl_init();
304 return 0;
305 }
306 __initcall(aio_setup);
307
308 static void put_aio_ring_file(struct kioctx *ctx)
309 {
310 struct file *aio_ring_file = ctx->aio_ring_file;
311 struct address_space *i_mapping;
312
313 if (aio_ring_file) {
314 truncate_setsize(file_inode(aio_ring_file), 0);
315
316 /* Prevent further access to the kioctx from migratepages */
317 i_mapping = aio_ring_file->f_mapping;
318 spin_lock(&i_mapping->i_private_lock);
319 i_mapping->i_private_data = NULL;
320 ctx->aio_ring_file = NULL;
321 spin_unlock(&i_mapping->i_private_lock);
322
323 fput(aio_ring_file);
324 }
325 }
326
327 static void aio_free_ring(struct kioctx *ctx)
328 {
329 int i;
330
331 /* Disconnect the kiotx from the ring file. This prevents future
332 * accesses to the kioctx from page migration.
333 */
334 put_aio_ring_file(ctx);
335
336 for (i = 0; i < ctx->nr_pages; i++) {
337 struct folio *folio = ctx->ring_folios[i];
338
339 if (!folio)
340 continue;
341
342 pr_debug("pid(%d) [%d] folio->count=%d\n", current->pid, i,
343 folio_ref_count(folio));
344 ctx->ring_folios[i] = NULL;
345 folio_put(folio);
346 }
347
348 if (ctx->ring_folios && ctx->ring_folios != ctx->internal_folios) {
349 kfree(ctx->ring_folios);
350 ctx->ring_folios = NULL;
351 }
352 }
353
354 static int aio_ring_mremap(struct vm_area_struct *vma)
355 {
356 struct file *file = vma->vm_file;
357 struct mm_struct *mm = vma->vm_mm;
358 struct kioctx_table *table;
359 int i, res = -EINVAL;
360
361 spin_lock(&mm->ioctx_lock);
362 rcu_read_lock();
363 table = rcu_dereference(mm->ioctx_table);
364 if (!table)
365 goto out_unlock;
366
367 for (i = 0; i < table->nr; i++) {
368 struct kioctx *ctx;
369
370 ctx = rcu_dereference(table->table[i]);
371 if (ctx && ctx->aio_ring_file == file) {
372 if (!atomic_read(&ctx->dead)) {
373 ctx->user_id = ctx->mmap_base = vma->vm_start;
374 res = 0;
375 }
376 break;
377 }
378 }
379
380 out_unlock:
381 rcu_read_unlock();
382 spin_unlock(&mm->ioctx_lock);
383 return res;
384 }
385
386 static const struct vm_operations_struct aio_ring_vm_ops = {
387 .mremap = aio_ring_mremap,
388 #if IS_ENABLED(CONFIG_MMU)
389 .fault = filemap_fault,
390 .map_pages = filemap_map_pages,
391 .page_mkwrite = filemap_page_mkwrite,
392 #endif
393 };
394
395 static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
396 {
397 vm_flags_set(vma, VM_DONTEXPAND);
398 vma->vm_ops = &aio_ring_vm_ops;
399 return 0;
400 }
401
402 static const struct file_operations aio_ring_fops = {
403 .mmap = aio_ring_mmap,
404 };
405
406 #if IS_ENABLED(CONFIG_MIGRATION)
407 static int aio_migrate_folio(struct address_space *mapping, struct folio *dst,
408 struct folio *src, enum migrate_mode mode)
409 {
410 struct kioctx *ctx;
411 unsigned long flags;
412 pgoff_t idx;
413 int rc = 0;
414
415 /* mapping->i_private_lock here protects against the kioctx teardown. */
416 spin_lock(&mapping->i_private_lock);
417 ctx = mapping->i_private_data;
418 if (!ctx) {
419 rc = -EINVAL;
420 goto out;
421 }
422
423 /* The ring_lock mutex. The prevents aio_read_events() from writing
424 * to the ring's head, and prevents page migration from mucking in
425 * a partially initialized kiotx.
426 */
427 if (!mutex_trylock(&ctx->ring_lock)) {
428 rc = -EAGAIN;
429 goto out;
430 }
431
432 idx = src->index;
433 if (idx < (pgoff_t)ctx->nr_pages) {
434 /* Make sure the old folio hasn't already been changed */
435 if (ctx->ring_folios[idx] != src)
436 rc = -EAGAIN;
437 } else
438 rc = -EINVAL;
439
440 if (rc != 0)
441 goto out_unlock;
442
443 /* Writeback must be complete */
444 BUG_ON(folio_test_writeback(src));
445 folio_get(dst);
446
447 rc = folio_migrate_mapping(mapping, dst, src, 1);
448 if (rc != MIGRATEPAGE_SUCCESS) {
449 folio_put(dst);
450 goto out_unlock;
451 }
452
453 /* Take completion_lock to prevent other writes to the ring buffer
454 * while the old folio is copied to the new. This prevents new
455 * events from being lost.
456 */
457 spin_lock_irqsave(&ctx->completion_lock, flags);
458 folio_copy(dst, src);
459 folio_migrate_flags(dst, src);
460 BUG_ON(ctx->ring_folios[idx] != src);
461 ctx->ring_folios[idx] = dst;
462 spin_unlock_irqrestore(&ctx->completion_lock, flags);
463
464 /* The old folio is no longer accessible. */
465 folio_put(src);
466
467 out_unlock:
468 mutex_unlock(&ctx->ring_lock);
469 out:
470 spin_unlock(&mapping->i_private_lock);
471 return rc;
472 }
473 #else
474 #define aio_migrate_folio NULL
475 #endif
476
477 static const struct address_space_operations aio_ctx_aops = {
478 .dirty_folio = noop_dirty_folio,
479 .migrate_folio = aio_migrate_folio,
480 };
481
482 static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
483 {
484 struct aio_ring *ring;
485 struct mm_struct *mm = current->mm;
486 unsigned long size, unused;
487 int nr_pages;
488 int i;
489 struct file *file;
490
491 /* Compensate for the ring buffer's head/tail overlap entry */
492 nr_events += 2; /* 1 is required, 2 for good luck */
493
494 size = sizeof(struct aio_ring);
495 size += sizeof(struct io_event) * nr_events;
496
497 nr_pages = PFN_UP(size);
498 if (nr_pages < 0)
499 return -EINVAL;
500
501 file = aio_private_file(ctx, nr_pages);
502 if (IS_ERR(file)) {
503 ctx->aio_ring_file = NULL;
504 return -ENOMEM;
505 }
506
507 ctx->aio_ring_file = file;
508 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
509 / sizeof(struct io_event);
510
511 ctx->ring_folios = ctx->internal_folios;
512 if (nr_pages > AIO_RING_PAGES) {
513 ctx->ring_folios = kcalloc(nr_pages, sizeof(struct folio *),
514 GFP_KERNEL);
515 if (!ctx->ring_folios) {
516 put_aio_ring_file(ctx);
517 return -ENOMEM;
518 }
519 }
520
521 for (i = 0; i < nr_pages; i++) {
522 struct folio *folio;
523
524 folio = __filemap_get_folio(file->f_mapping, i,
525 FGP_LOCK | FGP_ACCESSED | FGP_CREAT,
526 GFP_USER | __GFP_ZERO);
527 if (IS_ERR(folio))
528 break;
529
530 pr_debug("pid(%d) [%d] folio->count=%d\n", current->pid, i,
531 folio_ref_count(folio));
532 folio_end_read(folio, true);
533
534 ctx->ring_folios[i] = folio;
535 }
536 ctx->nr_pages = i;
537
538 if (unlikely(i != nr_pages)) {
539 aio_free_ring(ctx);
540 return -ENOMEM;
541 }
542
543 ctx->mmap_size = nr_pages * PAGE_SIZE;
544 pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
545
546 if (mmap_write_lock_killable(mm)) {
547 ctx->mmap_size = 0;
548 aio_free_ring(ctx);
549 return -EINTR;
550 }
551
552 ctx->mmap_base = do_mmap(ctx->aio_ring_file, 0, ctx->mmap_size,
553 PROT_READ | PROT_WRITE,
554 MAP_SHARED, 0, 0, &unused, NULL);
555 mmap_write_unlock(mm);
556 if (IS_ERR((void *)ctx->mmap_base)) {
557 ctx->mmap_size = 0;
558 aio_free_ring(ctx);
559 return -ENOMEM;
560 }
561
562 pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
563
564 ctx->user_id = ctx->mmap_base;
565 ctx->nr_events = nr_events; /* trusted copy */
566
567 ring = folio_address(ctx->ring_folios[0]);
568 ring->nr = nr_events; /* user copy */
569 ring->id = ~0U;
570 ring->head = ring->tail = 0;
571 ring->magic = AIO_RING_MAGIC;
572 ring->compat_features = AIO_RING_COMPAT_FEATURES;
573 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
574 ring->header_length = sizeof(struct aio_ring);
575 flush_dcache_folio(ctx->ring_folios[0]);
576
577 return 0;
578 }
579
580 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
581 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
582 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
583
584 void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
585 {
586 struct aio_kiocb *req;
587 struct kioctx *ctx;
588 unsigned long flags;
589
590 /*
591 * kiocb didn't come from aio or is neither a read nor a write, hence
592 * ignore it.
593 */
594 if (!(iocb->ki_flags & IOCB_AIO_RW))
595 return;
596
597 req = container_of(iocb, struct aio_kiocb, rw);
598
599 if (WARN_ON_ONCE(!list_empty(&req->ki_list)))
600 return;
601
602 ctx = req->ki_ctx;
603
604 spin_lock_irqsave(&ctx->ctx_lock, flags);
605 list_add_tail(&req->ki_list, &ctx->active_reqs);
606 req->ki_cancel = cancel;
607 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
608 }
609 EXPORT_SYMBOL(kiocb_set_cancel_fn);
610
611 /*
612 * free_ioctx() should be RCU delayed to synchronize against the RCU
613 * protected lookup_ioctx() and also needs process context to call
614 * aio_free_ring(). Use rcu_work.
615 */
616 static void free_ioctx(struct work_struct *work)
617 {
618 struct kioctx *ctx = container_of(to_rcu_work(work), struct kioctx,
619 free_rwork);
620 pr_debug("freeing %p\n", ctx);
621
622 aio_free_ring(ctx);
623 free_percpu(ctx->cpu);
624 percpu_ref_exit(&ctx->reqs);
625 percpu_ref_exit(&ctx->users);
626 kmem_cache_free(kioctx_cachep, ctx);
627 }
628
629 static void free_ioctx_reqs(struct percpu_ref *ref)
630 {
631 struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
632
633 /* At this point we know that there are no any in-flight requests */
634 if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
635 complete(&ctx->rq_wait->comp);
636
637 /* Synchronize against RCU protected table->table[] dereferences */
638 INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
639 queue_rcu_work(system_wq, &ctx->free_rwork);
640 }
641
642 /*
643 * When this function runs, the kioctx has been removed from the "hash table"
644 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
645 * now it's safe to cancel any that need to be.
646 */
647 static void free_ioctx_users(struct percpu_ref *ref)
648 {
649 struct kioctx *ctx = container_of(ref, struct kioctx, users);
650 struct aio_kiocb *req;
651
652 spin_lock_irq(&ctx->ctx_lock);
653
654 while (!list_empty(&ctx->active_reqs)) {
655 req = list_first_entry(&ctx->active_reqs,
656 struct aio_kiocb, ki_list);
657 req->ki_cancel(&req->rw);
658 list_del_init(&req->ki_list);
659 }
660
661 spin_unlock_irq(&ctx->ctx_lock);
662
663 percpu_ref_kill(&ctx->reqs);
664 percpu_ref_put(&ctx->reqs);
665 }
666
667 static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
668 {
669 unsigned i, new_nr;
670 struct kioctx_table *table, *old;
671 struct aio_ring *ring;
672
673 spin_lock(&mm->ioctx_lock);
674 table = rcu_dereference_raw(mm->ioctx_table);
675
676 while (1) {
677 if (table)
678 for (i = 0; i < table->nr; i++)
679 if (!rcu_access_pointer(table->table[i])) {
680 ctx->id = i;
681 rcu_assign_pointer(table->table[i], ctx);
682 spin_unlock(&mm->ioctx_lock);
683
684 /* While kioctx setup is in progress,
685 * we are protected from page migration
686 * changes ring_folios by ->ring_lock.
687 */
688 ring = folio_address(ctx->ring_folios[0]);
689 ring->id = ctx->id;
690 return 0;
691 }
692
693 new_nr = (table ? table->nr : 1) * 4;
694 spin_unlock(&mm->ioctx_lock);
695
696 table = kzalloc(struct_size(table, table, new_nr), GFP_KERNEL);
697 if (!table)
698 return -ENOMEM;
699
700 table->nr = new_nr;
701
702 spin_lock(&mm->ioctx_lock);
703 old = rcu_dereference_raw(mm->ioctx_table);
704
705 if (!old) {
706 rcu_assign_pointer(mm->ioctx_table, table);
707 } else if (table->nr > old->nr) {
708 memcpy(table->table, old->table,
709 old->nr * sizeof(struct kioctx *));
710
711 rcu_assign_pointer(mm->ioctx_table, table);
712 kfree_rcu(old, rcu);
713 } else {
714 kfree(table);
715 table = old;
716 }
717 }
718 }
719
720 static void aio_nr_sub(unsigned nr)
721 {
722 spin_lock(&aio_nr_lock);
723 if (WARN_ON(aio_nr - nr > aio_nr))
724 aio_nr = 0;
725 else
726 aio_nr -= nr;
727 spin_unlock(&aio_nr_lock);
728 }
729
730 /* ioctx_alloc
731 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
732 */
733 static struct kioctx *ioctx_alloc(unsigned nr_events)
734 {
735 struct mm_struct *mm = current->mm;
736 struct kioctx *ctx;
737 int err = -ENOMEM;
738
739 /*
740 * Store the original nr_events -- what userspace passed to io_setup(),
741 * for counting against the global limit -- before it changes.
742 */
743 unsigned int max_reqs = nr_events;
744
745 /*
746 * We keep track of the number of available ringbuffer slots, to prevent
747 * overflow (reqs_available), and we also use percpu counters for this.
748 *
749 * So since up to half the slots might be on other cpu's percpu counters
750 * and unavailable, double nr_events so userspace sees what they
751 * expected: additionally, we move req_batch slots to/from percpu
752 * counters at a time, so make sure that isn't 0:
753 */
754 nr_events = max(nr_events, num_possible_cpus() * 4);
755 nr_events *= 2;
756
757 /* Prevent overflows */
758 if (nr_events > (0x10000000U / sizeof(struct io_event))) {
759 pr_debug("ENOMEM: nr_events too high\n");
760 return ERR_PTR(-EINVAL);
761 }
762
763 if (!nr_events || (unsigned long)max_reqs > aio_max_nr)
764 return ERR_PTR(-EAGAIN);
765
766 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
767 if (!ctx)
768 return ERR_PTR(-ENOMEM);
769
770 ctx->max_reqs = max_reqs;
771
772 spin_lock_init(&ctx->ctx_lock);
773 spin_lock_init(&ctx->completion_lock);
774 mutex_init(&ctx->ring_lock);
775 /* Protect against page migration throughout kiotx setup by keeping
776 * the ring_lock mutex held until setup is complete. */
777 mutex_lock(&ctx->ring_lock);
778 init_waitqueue_head(&ctx->wait);
779
780 INIT_LIST_HEAD(&ctx->active_reqs);
781
782 if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL))
783 goto err;
784
785 if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL))
786 goto err;
787
788 ctx->cpu = alloc_percpu(struct kioctx_cpu);
789 if (!ctx->cpu)
790 goto err;
791
792 err = aio_setup_ring(ctx, nr_events);
793 if (err < 0)
794 goto err;
795
796 atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
797 ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
798 if (ctx->req_batch < 1)
799 ctx->req_batch = 1;
800
801 /* limit the number of system wide aios */
802 spin_lock(&aio_nr_lock);
803 if (aio_nr + ctx->max_reqs > aio_max_nr ||
804 aio_nr + ctx->max_reqs < aio_nr) {
805 spin_unlock(&aio_nr_lock);
806 err = -EAGAIN;
807 goto err_ctx;
808 }
809 aio_nr += ctx->max_reqs;
810 spin_unlock(&aio_nr_lock);
811
812 percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */
813 percpu_ref_get(&ctx->reqs); /* free_ioctx_users() will drop this */
814
815 err = ioctx_add_table(ctx, mm);
816 if (err)
817 goto err_cleanup;
818
819 /* Release the ring_lock mutex now that all setup is complete. */
820 mutex_unlock(&ctx->ring_lock);
821
822 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
823 ctx, ctx->user_id, mm, ctx->nr_events);
824 return ctx;
825
826 err_cleanup:
827 aio_nr_sub(ctx->max_reqs);
828 err_ctx:
829 atomic_set(&ctx->dead, 1);
830 if (ctx->mmap_size)
831 vm_munmap(ctx->mmap_base, ctx->mmap_size);
832 aio_free_ring(ctx);
833 err:
834 mutex_unlock(&ctx->ring_lock);
835 free_percpu(ctx->cpu);
836 percpu_ref_exit(&ctx->reqs);
837 percpu_ref_exit(&ctx->users);
838 kmem_cache_free(kioctx_cachep, ctx);
839 pr_debug("error allocating ioctx %d\n", err);
840 return ERR_PTR(err);
841 }
842
843 /* kill_ioctx
844 * Cancels all outstanding aio requests on an aio context. Used
845 * when the processes owning a context have all exited to encourage
846 * the rapid destruction of the kioctx.
847 */
848 static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
849 struct ctx_rq_wait *wait)
850 {
851 struct kioctx_table *table;
852
853 spin_lock(&mm->ioctx_lock);
854 if (atomic_xchg(&ctx->dead, 1)) {
855 spin_unlock(&mm->ioctx_lock);
856 return -EINVAL;
857 }
858
859 table = rcu_dereference_raw(mm->ioctx_table);
860 WARN_ON(ctx != rcu_access_pointer(table->table[ctx->id]));
861 RCU_INIT_POINTER(table->table[ctx->id], NULL);
862 spin_unlock(&mm->ioctx_lock);
863
864 /* free_ioctx_reqs() will do the necessary RCU synchronization */
865 wake_up_all(&ctx->wait);
866
867 /*
868 * It'd be more correct to do this in free_ioctx(), after all
869 * the outstanding kiocbs have finished - but by then io_destroy
870 * has already returned, so io_setup() could potentially return
871 * -EAGAIN with no ioctxs actually in use (as far as userspace
872 * could tell).
873 */
874 aio_nr_sub(ctx->max_reqs);
875
876 if (ctx->mmap_size)
877 vm_munmap(ctx->mmap_base, ctx->mmap_size);
878
879 ctx->rq_wait = wait;
880 percpu_ref_kill(&ctx->users);
881 return 0;
882 }
883
884 /*
885 * exit_aio: called when the last user of mm goes away. At this point, there is
886 * no way for any new requests to be submited or any of the io_* syscalls to be
887 * called on the context.
888 *
889 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
890 * them.
891 */
892 void exit_aio(struct mm_struct *mm)
893 {
894 struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
895 struct ctx_rq_wait wait;
896 int i, skipped;
897
898 if (!table)
899 return;
900
901 atomic_set(&wait.count, table->nr);
902 init_completion(&wait.comp);
903
904 skipped = 0;
905 for (i = 0; i < table->nr; ++i) {
906 struct kioctx *ctx =
907 rcu_dereference_protected(table->table[i], true);
908
909 if (!ctx) {
910 skipped++;
911 continue;
912 }
913
914 /*
915 * We don't need to bother with munmap() here - exit_mmap(mm)
916 * is coming and it'll unmap everything. And we simply can't,
917 * this is not necessarily our ->mm.
918 * Since kill_ioctx() uses non-zero ->mmap_size as indicator
919 * that it needs to unmap the area, just set it to 0.
920 */
921 ctx->mmap_size = 0;
922 kill_ioctx(mm, ctx, &wait);
923 }
924
925 if (!atomic_sub_and_test(skipped, &wait.count)) {
926 /* Wait until all IO for the context are done. */
927 wait_for_completion(&wait.comp);
928 }
929
930 RCU_INIT_POINTER(mm->ioctx_table, NULL);
931 kfree(table);
932 }
933
934 static void put_reqs_available(struct kioctx *ctx, unsigned nr)
935 {
936 struct kioctx_cpu *kcpu;
937 unsigned long flags;
938
939 local_irq_save(flags);
940 kcpu = this_cpu_ptr(ctx->cpu);
941 kcpu->reqs_available += nr;
942
943 while (kcpu->reqs_available >= ctx->req_batch * 2) {
944 kcpu->reqs_available -= ctx->req_batch;
945 atomic_add(ctx->req_batch, &ctx->reqs_available);
946 }
947
948 local_irq_restore(flags);
949 }
950
951 static bool __get_reqs_available(struct kioctx *ctx)
952 {
953 struct kioctx_cpu *kcpu;
954 bool ret = false;
955 unsigned long flags;
956
957 local_irq_save(flags);
958 kcpu = this_cpu_ptr(ctx->cpu);
959 if (!kcpu->reqs_available) {
960 int avail = atomic_read(&ctx->reqs_available);
961
962 do {
963 if (avail < ctx->req_batch)
964 goto out;
965 } while (!atomic_try_cmpxchg(&ctx->reqs_available,
966 &avail, avail - ctx->req_batch));
967
968 kcpu->reqs_available += ctx->req_batch;
969 }
970
971 ret = true;
972 kcpu->reqs_available--;
973 out:
974 local_irq_restore(flags);
975 return ret;
976 }
977
978 /* refill_reqs_available
979 * Updates the reqs_available reference counts used for tracking the
980 * number of free slots in the completion ring. This can be called
981 * from aio_complete() (to optimistically update reqs_available) or
982 * from aio_get_req() (the we're out of events case). It must be
983 * called holding ctx->completion_lock.
984 */
985 static void refill_reqs_available(struct kioctx *ctx, unsigned head,
986 unsigned tail)
987 {
988 unsigned events_in_ring, completed;
989
990 /* Clamp head since userland can write to it. */
991 head %= ctx->nr_events;
992 if (head <= tail)
993 events_in_ring = tail - head;
994 else
995 events_in_ring = ctx->nr_events - (head - tail);
996
997 completed = ctx->completed_events;
998 if (events_in_ring < completed)
999 completed -= events_in_ring;
1000 else
1001 completed = 0;
1002
1003 if (!completed)
1004 return;
1005
1006 ctx->completed_events -= completed;
1007 put_reqs_available(ctx, completed);
1008 }
1009
1010 /* user_refill_reqs_available
1011 * Called to refill reqs_available when aio_get_req() encounters an
1012 * out of space in the completion ring.
1013 */
1014 static void user_refill_reqs_available(struct kioctx *ctx)
1015 {
1016 spin_lock_irq(&ctx->completion_lock);
1017 if (ctx->completed_events) {
1018 struct aio_ring *ring;
1019 unsigned head;
1020
1021 /* Access of ring->head may race with aio_read_events_ring()
1022 * here, but that's okay since whether we read the old version
1023 * or the new version, and either will be valid. The important
1024 * part is that head cannot pass tail since we prevent
1025 * aio_complete() from updating tail by holding
1026 * ctx->completion_lock. Even if head is invalid, the check
1027 * against ctx->completed_events below will make sure we do the
1028 * safe/right thing.
1029 */
1030 ring = folio_address(ctx->ring_folios[0]);
1031 head = ring->head;
1032
1033 refill_reqs_available(ctx, head, ctx->tail);
1034 }
1035
1036 spin_unlock_irq(&ctx->completion_lock);
1037 }
1038
1039 static bool get_reqs_available(struct kioctx *ctx)
1040 {
1041 if (__get_reqs_available(ctx))
1042 return true;
1043 user_refill_reqs_available(ctx);
1044 return __get_reqs_available(ctx);
1045 }
1046
1047 /* aio_get_req
1048 * Allocate a slot for an aio request.
1049 * Returns NULL if no requests are free.
1050 *
1051 * The refcount is initialized to 2 - one for the async op completion,
1052 * one for the synchronous code that does this.
1053 */
1054 static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
1055 {
1056 struct aio_kiocb *req;
1057
1058 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
1059 if (unlikely(!req))
1060 return NULL;
1061
1062 if (unlikely(!get_reqs_available(ctx))) {
1063 kmem_cache_free(kiocb_cachep, req);
1064 return NULL;
1065 }
1066
1067 percpu_ref_get(&ctx->reqs);
1068 req->ki_ctx = ctx;
1069 INIT_LIST_HEAD(&req->ki_list);
1070 refcount_set(&req->ki_refcnt, 2);
1071 req->ki_eventfd = NULL;
1072 return req;
1073 }
1074
1075 static struct kioctx *lookup_ioctx(unsigned long ctx_id)
1076 {
1077 struct aio_ring __user *ring = (void __user *)ctx_id;
1078 struct mm_struct *mm = current->mm;
1079 struct kioctx *ctx, *ret = NULL;
1080 struct kioctx_table *table;
1081 unsigned id;
1082
1083 if (get_user(id, &ring->id))
1084 return NULL;
1085
1086 rcu_read_lock();
1087 table = rcu_dereference(mm->ioctx_table);
1088
1089 if (!table || id >= table->nr)
1090 goto out;
1091
1092 id = array_index_nospec(id, table->nr);
1093 ctx = rcu_dereference(table->table[id]);
1094 if (ctx && ctx->user_id == ctx_id) {
1095 if (percpu_ref_tryget_live(&ctx->users))
1096 ret = ctx;
1097 }
1098 out:
1099 rcu_read_unlock();
1100 return ret;
1101 }
1102
1103 static inline void iocb_destroy(struct aio_kiocb *iocb)
1104 {
1105 if (iocb->ki_eventfd)
1106 eventfd_ctx_put(iocb->ki_eventfd);
1107 if (iocb->ki_filp)
1108 fput(iocb->ki_filp);
1109 percpu_ref_put(&iocb->ki_ctx->reqs);
1110 kmem_cache_free(kiocb_cachep, iocb);
1111 }
1112
1113 struct aio_waiter {
1114 struct wait_queue_entry w;
1115 size_t min_nr;
1116 };
1117
1118 /* aio_complete
1119 * Called when the io request on the given iocb is complete.
1120 */
1121 static void aio_complete(struct aio_kiocb *iocb)
1122 {
1123 struct kioctx *ctx = iocb->ki_ctx;
1124 struct aio_ring *ring;
1125 struct io_event *ev_page, *event;
1126 unsigned tail, pos, head, avail;
1127 unsigned long flags;
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 = folio_address(ctx->ring_folios[pos / AIO_EVENTS_PER_PAGE]);
1143 event = ev_page + pos % AIO_EVENTS_PER_PAGE;
1144
1145 *event = iocb->ki_res;
1146
1147 flush_dcache_folio(ctx->ring_folios[pos / AIO_EVENTS_PER_PAGE]);
1148
1149 pr_debug("%p[%u]: %p: %p %Lx %Lx %Lx\n", ctx, tail, iocb,
1150 (void __user *)(unsigned long)iocb->ki_res.obj,
1151 iocb->ki_res.data, iocb->ki_res.res, iocb->ki_res.res2);
1152
1153 /* after flagging the request as done, we
1154 * must never even look at it again
1155 */
1156 smp_wmb(); /* make event visible before updating tail */
1157
1158 ctx->tail = tail;
1159
1160 ring = folio_address(ctx->ring_folios[0]);
1161 head = ring->head;
1162 ring->tail = tail;
1163 flush_dcache_folio(ctx->ring_folios[0]);
1164
1165 ctx->completed_events++;
1166 if (ctx->completed_events > 1)
1167 refill_reqs_available(ctx, head, tail);
1168
1169 avail = tail > head
1170 ? tail - head
1171 : tail + ctx->nr_events - head;
1172 spin_unlock_irqrestore(&ctx->completion_lock, flags);
1173
1174 pr_debug("added to ring %p at [%u]\n", iocb, tail);
1175
1176 /*
1177 * Check if the user asked us to deliver the result through an
1178 * eventfd. The eventfd_signal() function is safe to be called
1179 * from IRQ context.
1180 */
1181 if (iocb->ki_eventfd)
1182 eventfd_signal(iocb->ki_eventfd);
1183
1184 /*
1185 * We have to order our ring_info tail store above and test
1186 * of the wait list below outside the wait lock. This is
1187 * like in wake_up_bit() where clearing a bit has to be
1188 * ordered with the unlocked test.
1189 */
1190 smp_mb();
1191
1192 if (waitqueue_active(&ctx->wait)) {
1193 struct aio_waiter *curr, *next;
1194 unsigned long flags;
1195
1196 spin_lock_irqsave(&ctx->wait.lock, flags);
1197 list_for_each_entry_safe(curr, next, &ctx->wait.head, w.entry)
1198 if (avail >= curr->min_nr) {
1199 wake_up_process(curr->w.private);
1200 list_del_init_careful(&curr->w.entry);
1201 }
1202 spin_unlock_irqrestore(&ctx->wait.lock, flags);
1203 }
1204 }
1205
1206 static inline void iocb_put(struct aio_kiocb *iocb)
1207 {
1208 if (refcount_dec_and_test(&iocb->ki_refcnt)) {
1209 aio_complete(iocb);
1210 iocb_destroy(iocb);
1211 }
1212 }
1213
1214 /* aio_read_events_ring
1215 * Pull an event off of the ioctx's event ring. Returns the number of
1216 * events fetched
1217 */
1218 static long aio_read_events_ring(struct kioctx *ctx,
1219 struct io_event __user *event, long nr)
1220 {
1221 struct aio_ring *ring;
1222 unsigned head, tail, pos;
1223 long ret = 0;
1224 int copy_ret;
1225
1226 /*
1227 * The mutex can block and wake us up and that will cause
1228 * wait_event_interruptible_hrtimeout() to schedule without sleeping
1229 * and repeat. This should be rare enough that it doesn't cause
1230 * peformance issues. See the comment in read_events() for more detail.
1231 */
1232 sched_annotate_sleep();
1233 mutex_lock(&ctx->ring_lock);
1234
1235 /* Access to ->ring_folios here is protected by ctx->ring_lock. */
1236 ring = folio_address(ctx->ring_folios[0]);
1237 head = ring->head;
1238 tail = ring->tail;
1239
1240 /*
1241 * Ensure that once we've read the current tail pointer, that
1242 * we also see the events that were stored up to the tail.
1243 */
1244 smp_rmb();
1245
1246 pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
1247
1248 if (head == tail)
1249 goto out;
1250
1251 head %= ctx->nr_events;
1252 tail %= ctx->nr_events;
1253
1254 while (ret < nr) {
1255 long avail;
1256 struct io_event *ev;
1257 struct folio *folio;
1258
1259 avail = (head <= tail ? tail : ctx->nr_events) - head;
1260 if (head == tail)
1261 break;
1262
1263 pos = head + AIO_EVENTS_OFFSET;
1264 folio = ctx->ring_folios[pos / AIO_EVENTS_PER_PAGE];
1265 pos %= AIO_EVENTS_PER_PAGE;
1266
1267 avail = min(avail, nr - ret);
1268 avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
1269
1270 ev = folio_address(folio);
1271 copy_ret = copy_to_user(event + ret, ev + pos,
1272 sizeof(*ev) * avail);
1273
1274 if (unlikely(copy_ret)) {
1275 ret = -EFAULT;
1276 goto out;
1277 }
1278
1279 ret += avail;
1280 head += avail;
1281 head %= ctx->nr_events;
1282 }
1283
1284 ring = folio_address(ctx->ring_folios[0]);
1285 ring->head = head;
1286 flush_dcache_folio(ctx->ring_folios[0]);
1287
1288 pr_debug("%li h%u t%u\n", ret, head, tail);
1289 out:
1290 mutex_unlock(&ctx->ring_lock);
1291
1292 return ret;
1293 }
1294
1295 static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
1296 struct io_event __user *event, long *i)
1297 {
1298 long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
1299
1300 if (ret > 0)
1301 *i += ret;
1302
1303 if (unlikely(atomic_read(&ctx->dead)))
1304 ret = -EINVAL;
1305
1306 if (!*i)
1307 *i = ret;
1308
1309 return ret < 0 || *i >= min_nr;
1310 }
1311
1312 static long read_events(struct kioctx *ctx, long min_nr, long nr,
1313 struct io_event __user *event,
1314 ktime_t until)
1315 {
1316 struct hrtimer_sleeper t;
1317 struct aio_waiter w;
1318 long ret = 0, ret2 = 0;
1319
1320 /*
1321 * Note that aio_read_events() is being called as the conditional - i.e.
1322 * we're calling it after prepare_to_wait() has set task state to
1323 * TASK_INTERRUPTIBLE.
1324 *
1325 * But aio_read_events() can block, and if it blocks it's going to flip
1326 * the task state back to TASK_RUNNING.
1327 *
1328 * This should be ok, provided it doesn't flip the state back to
1329 * TASK_RUNNING and return 0 too much - that causes us to spin. That
1330 * will only happen if the mutex_lock() call blocks, and we then find
1331 * the ringbuffer empty. So in practice we should be ok, but it's
1332 * something to be aware of when touching this code.
1333 */
1334 aio_read_events(ctx, min_nr, nr, event, &ret);
1335 if (until == 0 || ret < 0 || ret >= min_nr)
1336 return ret;
1337
1338 hrtimer_init_sleeper_on_stack(&t, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1339 if (until != KTIME_MAX) {
1340 hrtimer_set_expires_range_ns(&t.timer, until, current->timer_slack_ns);
1341 hrtimer_sleeper_start_expires(&t, HRTIMER_MODE_REL);
1342 }
1343
1344 init_wait(&w.w);
1345
1346 while (1) {
1347 unsigned long nr_got = ret;
1348
1349 w.min_nr = min_nr - ret;
1350
1351 ret2 = prepare_to_wait_event(&ctx->wait, &w.w, TASK_INTERRUPTIBLE);
1352 if (!ret2 && !t.task)
1353 ret2 = -ETIME;
1354
1355 if (aio_read_events(ctx, min_nr, nr, event, &ret) || ret2)
1356 break;
1357
1358 if (nr_got == ret)
1359 schedule();
1360 }
1361
1362 finish_wait(&ctx->wait, &w.w);
1363 hrtimer_cancel(&t.timer);
1364 destroy_hrtimer_on_stack(&t.timer);
1365
1366 return ret;
1367 }
1368
1369 /* sys_io_setup:
1370 * Create an aio_context capable of receiving at least nr_events.
1371 * ctxp must not point to an aio_context that already exists, and
1372 * must be initialized to 0 prior to the call. On successful
1373 * creation of the aio_context, *ctxp is filled in with the resulting
1374 * handle. May fail with -EINVAL if *ctxp is not initialized,
1375 * if the specified nr_events exceeds internal limits. May fail
1376 * with -EAGAIN if the specified nr_events exceeds the user's limit
1377 * of available events. May fail with -ENOMEM if insufficient kernel
1378 * resources are available. May fail with -EFAULT if an invalid
1379 * pointer is passed for ctxp. Will fail with -ENOSYS if not
1380 * implemented.
1381 */
1382 SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1383 {
1384 struct kioctx *ioctx = NULL;
1385 unsigned long ctx;
1386 long ret;
1387
1388 ret = get_user(ctx, ctxp);
1389 if (unlikely(ret))
1390 goto out;
1391
1392 ret = -EINVAL;
1393 if (unlikely(ctx || nr_events == 0)) {
1394 pr_debug("EINVAL: ctx %lu nr_events %u\n",
1395 ctx, nr_events);
1396 goto out;
1397 }
1398
1399 ioctx = ioctx_alloc(nr_events);
1400 ret = PTR_ERR(ioctx);
1401 if (!IS_ERR(ioctx)) {
1402 ret = put_user(ioctx->user_id, ctxp);
1403 if (ret)
1404 kill_ioctx(current->mm, ioctx, NULL);
1405 percpu_ref_put(&ioctx->users);
1406 }
1407
1408 out:
1409 return ret;
1410 }
1411
1412 #ifdef CONFIG_COMPAT
1413 COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
1414 {
1415 struct kioctx *ioctx = NULL;
1416 unsigned long ctx;
1417 long ret;
1418
1419 ret = get_user(ctx, ctx32p);
1420 if (unlikely(ret))
1421 goto out;
1422
1423 ret = -EINVAL;
1424 if (unlikely(ctx || nr_events == 0)) {
1425 pr_debug("EINVAL: ctx %lu nr_events %u\n",
1426 ctx, nr_events);
1427 goto out;
1428 }
1429
1430 ioctx = ioctx_alloc(nr_events);
1431 ret = PTR_ERR(ioctx);
1432 if (!IS_ERR(ioctx)) {
1433 /* truncating is ok because it's a user address */
1434 ret = put_user((u32)ioctx->user_id, ctx32p);
1435 if (ret)
1436 kill_ioctx(current->mm, ioctx, NULL);
1437 percpu_ref_put(&ioctx->users);
1438 }
1439
1440 out:
1441 return ret;
1442 }
1443 #endif
1444
1445 /* sys_io_destroy:
1446 * Destroy the aio_context specified. May cancel any outstanding
1447 * AIOs and block on completion. Will fail with -ENOSYS if not
1448 * implemented. May fail with -EINVAL if the context pointed to
1449 * is invalid.
1450 */
1451 SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1452 {
1453 struct kioctx *ioctx = lookup_ioctx(ctx);
1454 if (likely(NULL != ioctx)) {
1455 struct ctx_rq_wait wait;
1456 int ret;
1457
1458 init_completion(&wait.comp);
1459 atomic_set(&wait.count, 1);
1460
1461 /* Pass requests_done to kill_ioctx() where it can be set
1462 * in a thread-safe way. If we try to set it here then we have
1463 * a race condition if two io_destroy() called simultaneously.
1464 */
1465 ret = kill_ioctx(current->mm, ioctx, &wait);
1466 percpu_ref_put(&ioctx->users);
1467
1468 /* Wait until all IO for the context are done. Otherwise kernel
1469 * keep using user-space buffers even if user thinks the context
1470 * is destroyed.
1471 */
1472 if (!ret)
1473 wait_for_completion(&wait.comp);
1474
1475 return ret;
1476 }
1477 pr_debug("EINVAL: invalid context id\n");
1478 return -EINVAL;
1479 }
1480
1481 static void aio_remove_iocb(struct aio_kiocb *iocb)
1482 {
1483 struct kioctx *ctx = iocb->ki_ctx;
1484 unsigned long flags;
1485
1486 spin_lock_irqsave(&ctx->ctx_lock, flags);
1487 list_del(&iocb->ki_list);
1488 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1489 }
1490
1491 static void aio_complete_rw(struct kiocb *kiocb, long res)
1492 {
1493 struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, rw);
1494
1495 if (!list_empty_careful(&iocb->ki_list))
1496 aio_remove_iocb(iocb);
1497
1498 if (kiocb->ki_flags & IOCB_WRITE) {
1499 struct inode *inode = file_inode(kiocb->ki_filp);
1500
1501 if (S_ISREG(inode->i_mode))
1502 kiocb_end_write(kiocb);
1503 }
1504
1505 iocb->ki_res.res = res;
1506 iocb->ki_res.res2 = 0;
1507 iocb_put(iocb);
1508 }
1509
1510 static int aio_prep_rw(struct kiocb *req, const struct iocb *iocb, int rw_type)
1511 {
1512 int ret;
1513
1514 req->ki_complete = aio_complete_rw;
1515 req->private = NULL;
1516 req->ki_pos = iocb->aio_offset;
1517 req->ki_flags = req->ki_filp->f_iocb_flags | IOCB_AIO_RW;
1518 if (iocb->aio_flags & IOCB_FLAG_RESFD)
1519 req->ki_flags |= IOCB_EVENTFD;
1520 if (iocb->aio_flags & IOCB_FLAG_IOPRIO) {
1521 /*
1522 * If the IOCB_FLAG_IOPRIO flag of aio_flags is set, then
1523 * aio_reqprio is interpreted as an I/O scheduling
1524 * class and priority.
1525 */
1526 ret = ioprio_check_cap(iocb->aio_reqprio);
1527 if (ret) {
1528 pr_debug("aio ioprio check cap error: %d\n", ret);
1529 return ret;
1530 }
1531
1532 req->ki_ioprio = iocb->aio_reqprio;
1533 } else
1534 req->ki_ioprio = get_current_ioprio();
1535
1536 ret = kiocb_set_rw_flags(req, iocb->aio_rw_flags, rw_type);
1537 if (unlikely(ret))
1538 return ret;
1539
1540 req->ki_flags &= ~IOCB_HIPRI; /* no one is going to poll for this I/O */
1541 return 0;
1542 }
1543
1544 static ssize_t aio_setup_rw(int rw, const struct iocb *iocb,
1545 struct iovec **iovec, bool vectored, bool compat,
1546 struct iov_iter *iter)
1547 {
1548 void __user *buf = (void __user *)(uintptr_t)iocb->aio_buf;
1549 size_t len = iocb->aio_nbytes;
1550
1551 if (!vectored) {
1552 ssize_t ret = import_ubuf(rw, buf, len, iter);
1553 *iovec = NULL;
1554 return ret;
1555 }
1556
1557 return __import_iovec(rw, buf, len, UIO_FASTIOV, iovec, iter, compat);
1558 }
1559
1560 static inline void aio_rw_done(struct kiocb *req, ssize_t ret)
1561 {
1562 switch (ret) {
1563 case -EIOCBQUEUED:
1564 break;
1565 case -ERESTARTSYS:
1566 case -ERESTARTNOINTR:
1567 case -ERESTARTNOHAND:
1568 case -ERESTART_RESTARTBLOCK:
1569 /*
1570 * There's no easy way to restart the syscall since other AIO's
1571 * may be already running. Just fail this IO with EINTR.
1572 */
1573 ret = -EINTR;
1574 fallthrough;
1575 default:
1576 req->ki_complete(req, ret);
1577 }
1578 }
1579
1580 static int aio_read(struct kiocb *req, const struct iocb *iocb,
1581 bool vectored, bool compat)
1582 {
1583 struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1584 struct iov_iter iter;
1585 struct file *file;
1586 int ret;
1587
1588 ret = aio_prep_rw(req, iocb, READ);
1589 if (ret)
1590 return ret;
1591 file = req->ki_filp;
1592 if (unlikely(!(file->f_mode & FMODE_READ)))
1593 return -EBADF;
1594 if (unlikely(!file->f_op->read_iter))
1595 return -EINVAL;
1596
1597 ret = aio_setup_rw(ITER_DEST, iocb, &iovec, vectored, compat, &iter);
1598 if (ret < 0)
1599 return ret;
1600 ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(&iter));
1601 if (!ret)
1602 aio_rw_done(req, file->f_op->read_iter(req, &iter));
1603 kfree(iovec);
1604 return ret;
1605 }
1606
1607 static int aio_write(struct kiocb *req, const struct iocb *iocb,
1608 bool vectored, bool compat)
1609 {
1610 struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1611 struct iov_iter iter;
1612 struct file *file;
1613 int ret;
1614
1615 ret = aio_prep_rw(req, iocb, WRITE);
1616 if (ret)
1617 return ret;
1618 file = req->ki_filp;
1619
1620 if (unlikely(!(file->f_mode & FMODE_WRITE)))
1621 return -EBADF;
1622 if (unlikely(!file->f_op->write_iter))
1623 return -EINVAL;
1624
1625 ret = aio_setup_rw(ITER_SOURCE, iocb, &iovec, vectored, compat, &iter);
1626 if (ret < 0)
1627 return ret;
1628 ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
1629 if (!ret) {
1630 if (S_ISREG(file_inode(file)->i_mode))
1631 kiocb_start_write(req);
1632 req->ki_flags |= IOCB_WRITE;
1633 aio_rw_done(req, file->f_op->write_iter(req, &iter));
1634 }
1635 kfree(iovec);
1636 return ret;
1637 }
1638
1639 static void aio_fsync_work(struct work_struct *work)
1640 {
1641 struct aio_kiocb *iocb = container_of(work, struct aio_kiocb, fsync.work);
1642 const struct cred *old_cred = override_creds(iocb->fsync.creds);
1643
1644 iocb->ki_res.res = vfs_fsync(iocb->fsync.file, iocb->fsync.datasync);
1645 revert_creds(old_cred);
1646 put_cred(iocb->fsync.creds);
1647 iocb_put(iocb);
1648 }
1649
1650 static int aio_fsync(struct fsync_iocb *req, const struct iocb *iocb,
1651 bool datasync)
1652 {
1653 if (unlikely(iocb->aio_buf || iocb->aio_offset || iocb->aio_nbytes ||
1654 iocb->aio_rw_flags))
1655 return -EINVAL;
1656
1657 if (unlikely(!req->file->f_op->fsync))
1658 return -EINVAL;
1659
1660 req->creds = prepare_creds();
1661 if (!req->creds)
1662 return -ENOMEM;
1663
1664 req->datasync = datasync;
1665 INIT_WORK(&req->work, aio_fsync_work);
1666 schedule_work(&req->work);
1667 return 0;
1668 }
1669
1670 static void aio_poll_put_work(struct work_struct *work)
1671 {
1672 struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1673 struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1674
1675 iocb_put(iocb);
1676 }
1677
1678 /*
1679 * Safely lock the waitqueue which the request is on, synchronizing with the
1680 * case where the ->poll() provider decides to free its waitqueue early.
1681 *
1682 * Returns true on success, meaning that req->head->lock was locked, req->wait
1683 * is on req->head, and an RCU read lock was taken. Returns false if the
1684 * request was already removed from its waitqueue (which might no longer exist).
1685 */
1686 static bool poll_iocb_lock_wq(struct poll_iocb *req)
1687 {
1688 wait_queue_head_t *head;
1689
1690 /*
1691 * While we hold the waitqueue lock and the waitqueue is nonempty,
1692 * wake_up_pollfree() will wait for us. However, taking the waitqueue
1693 * lock in the first place can race with the waitqueue being freed.
1694 *
1695 * We solve this as eventpoll does: by taking advantage of the fact that
1696 * all users of wake_up_pollfree() will RCU-delay the actual free. If
1697 * we enter rcu_read_lock() and see that the pointer to the queue is
1698 * non-NULL, we can then lock it without the memory being freed out from
1699 * under us, then check whether the request is still on the queue.
1700 *
1701 * Keep holding rcu_read_lock() as long as we hold the queue lock, in
1702 * case the caller deletes the entry from the queue, leaving it empty.
1703 * In that case, only RCU prevents the queue memory from being freed.
1704 */
1705 rcu_read_lock();
1706 head = smp_load_acquire(&req->head);
1707 if (head) {
1708 spin_lock(&head->lock);
1709 if (!list_empty(&req->wait.entry))
1710 return true;
1711 spin_unlock(&head->lock);
1712 }
1713 rcu_read_unlock();
1714 return false;
1715 }
1716
1717 static void poll_iocb_unlock_wq(struct poll_iocb *req)
1718 {
1719 spin_unlock(&req->head->lock);
1720 rcu_read_unlock();
1721 }
1722
1723 static void aio_poll_complete_work(struct work_struct *work)
1724 {
1725 struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1726 struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1727 struct poll_table_struct pt = { ._key = req->events };
1728 struct kioctx *ctx = iocb->ki_ctx;
1729 __poll_t mask = 0;
1730
1731 if (!READ_ONCE(req->cancelled))
1732 mask = vfs_poll(req->file, &pt) & req->events;
1733
1734 /*
1735 * Note that ->ki_cancel callers also delete iocb from active_reqs after
1736 * calling ->ki_cancel. We need the ctx_lock roundtrip here to
1737 * synchronize with them. In the cancellation case the list_del_init
1738 * itself is not actually needed, but harmless so we keep it in to
1739 * avoid further branches in the fast path.
1740 */
1741 spin_lock_irq(&ctx->ctx_lock);
1742 if (poll_iocb_lock_wq(req)) {
1743 if (!mask && !READ_ONCE(req->cancelled)) {
1744 /*
1745 * The request isn't actually ready to be completed yet.
1746 * Reschedule completion if another wakeup came in.
1747 */
1748 if (req->work_need_resched) {
1749 schedule_work(&req->work);
1750 req->work_need_resched = false;
1751 } else {
1752 req->work_scheduled = false;
1753 }
1754 poll_iocb_unlock_wq(req);
1755 spin_unlock_irq(&ctx->ctx_lock);
1756 return;
1757 }
1758 list_del_init(&req->wait.entry);
1759 poll_iocb_unlock_wq(req);
1760 } /* else, POLLFREE has freed the waitqueue, so we must complete */
1761 list_del_init(&iocb->ki_list);
1762 iocb->ki_res.res = mangle_poll(mask);
1763 spin_unlock_irq(&ctx->ctx_lock);
1764
1765 iocb_put(iocb);
1766 }
1767
1768 /* assumes we are called with irqs disabled */
1769 static int aio_poll_cancel(struct kiocb *iocb)
1770 {
1771 struct aio_kiocb *aiocb = container_of(iocb, struct aio_kiocb, rw);
1772 struct poll_iocb *req = &aiocb->poll;
1773
1774 if (poll_iocb_lock_wq(req)) {
1775 WRITE_ONCE(req->cancelled, true);
1776 if (!req->work_scheduled) {
1777 schedule_work(&aiocb->poll.work);
1778 req->work_scheduled = true;
1779 }
1780 poll_iocb_unlock_wq(req);
1781 } /* else, the request was force-cancelled by POLLFREE already */
1782
1783 return 0;
1784 }
1785
1786 static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
1787 void *key)
1788 {
1789 struct poll_iocb *req = container_of(wait, struct poll_iocb, wait);
1790 struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1791 __poll_t mask = key_to_poll(key);
1792 unsigned long flags;
1793
1794 /* for instances that support it check for an event match first: */
1795 if (mask && !(mask & req->events))
1796 return 0;
1797
1798 /*
1799 * Complete the request inline if possible. This requires that three
1800 * conditions be met:
1801 * 1. An event mask must have been passed. If a plain wakeup was done
1802 * instead, then mask == 0 and we have to call vfs_poll() to get
1803 * the events, so inline completion isn't possible.
1804 * 2. The completion work must not have already been scheduled.
1805 * 3. ctx_lock must not be busy. We have to use trylock because we
1806 * already hold the waitqueue lock, so this inverts the normal
1807 * locking order. Use irqsave/irqrestore because not all
1808 * filesystems (e.g. fuse) call this function with IRQs disabled,
1809 * yet IRQs have to be disabled before ctx_lock is obtained.
1810 */
1811 if (mask && !req->work_scheduled &&
1812 spin_trylock_irqsave(&iocb->ki_ctx->ctx_lock, flags)) {
1813 struct kioctx *ctx = iocb->ki_ctx;
1814
1815 list_del_init(&req->wait.entry);
1816 list_del(&iocb->ki_list);
1817 iocb->ki_res.res = mangle_poll(mask);
1818 if (iocb->ki_eventfd && !eventfd_signal_allowed()) {
1819 iocb = NULL;
1820 INIT_WORK(&req->work, aio_poll_put_work);
1821 schedule_work(&req->work);
1822 }
1823 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1824 if (iocb)
1825 iocb_put(iocb);
1826 } else {
1827 /*
1828 * Schedule the completion work if needed. If it was already
1829 * scheduled, record that another wakeup came in.
1830 *
1831 * Don't remove the request from the waitqueue here, as it might
1832 * not actually be complete yet (we won't know until vfs_poll()
1833 * is called), and we must not miss any wakeups. POLLFREE is an
1834 * exception to this; see below.
1835 */
1836 if (req->work_scheduled) {
1837 req->work_need_resched = true;
1838 } else {
1839 schedule_work(&req->work);
1840 req->work_scheduled = true;
1841 }
1842
1843 /*
1844 * If the waitqueue is being freed early but we can't complete
1845 * the request inline, we have to tear down the request as best
1846 * we can. That means immediately removing the request from its
1847 * waitqueue and preventing all further accesses to the
1848 * waitqueue via the request. We also need to schedule the
1849 * completion work (done above). Also mark the request as
1850 * cancelled, to potentially skip an unneeded call to ->poll().
1851 */
1852 if (mask & POLLFREE) {
1853 WRITE_ONCE(req->cancelled, true);
1854 list_del_init(&req->wait.entry);
1855
1856 /*
1857 * Careful: this *must* be the last step, since as soon
1858 * as req->head is NULL'ed out, the request can be
1859 * completed and freed, since aio_poll_complete_work()
1860 * will no longer need to take the waitqueue lock.
1861 */
1862 smp_store_release(&req->head, NULL);
1863 }
1864 }
1865 return 1;
1866 }
1867
1868 struct aio_poll_table {
1869 struct poll_table_struct pt;
1870 struct aio_kiocb *iocb;
1871 bool queued;
1872 int error;
1873 };
1874
1875 static void
1876 aio_poll_queue_proc(struct file *file, struct wait_queue_head *head,
1877 struct poll_table_struct *p)
1878 {
1879 struct aio_poll_table *pt = container_of(p, struct aio_poll_table, pt);
1880
1881 /* multiple wait queues per file are not supported */
1882 if (unlikely(pt->queued)) {
1883 pt->error = -EINVAL;
1884 return;
1885 }
1886
1887 pt->queued = true;
1888 pt->error = 0;
1889 pt->iocb->poll.head = head;
1890 add_wait_queue(head, &pt->iocb->poll.wait);
1891 }
1892
1893 static int aio_poll(struct aio_kiocb *aiocb, const struct iocb *iocb)
1894 {
1895 struct kioctx *ctx = aiocb->ki_ctx;
1896 struct poll_iocb *req = &aiocb->poll;
1897 struct aio_poll_table apt;
1898 bool cancel = false;
1899 __poll_t mask;
1900
1901 /* reject any unknown events outside the normal event mask. */
1902 if ((u16)iocb->aio_buf != iocb->aio_buf)
1903 return -EINVAL;
1904 /* reject fields that are not defined for poll */
1905 if (iocb->aio_offset || iocb->aio_nbytes || iocb->aio_rw_flags)
1906 return -EINVAL;
1907
1908 INIT_WORK(&req->work, aio_poll_complete_work);
1909 req->events = demangle_poll(iocb->aio_buf) | EPOLLERR | EPOLLHUP;
1910
1911 req->head = NULL;
1912 req->cancelled = false;
1913 req->work_scheduled = false;
1914 req->work_need_resched = false;
1915
1916 apt.pt._qproc = aio_poll_queue_proc;
1917 apt.pt._key = req->events;
1918 apt.iocb = aiocb;
1919 apt.queued = false;
1920 apt.error = -EINVAL; /* same as no support for IOCB_CMD_POLL */
1921
1922 /* initialized the list so that we can do list_empty checks */
1923 INIT_LIST_HEAD(&req->wait.entry);
1924 init_waitqueue_func_entry(&req->wait, aio_poll_wake);
1925
1926 mask = vfs_poll(req->file, &apt.pt) & req->events;
1927 spin_lock_irq(&ctx->ctx_lock);
1928 if (likely(apt.queued)) {
1929 bool on_queue = poll_iocb_lock_wq(req);
1930
1931 if (!on_queue || req->work_scheduled) {
1932 /*
1933 * aio_poll_wake() already either scheduled the async
1934 * completion work, or completed the request inline.
1935 */
1936 if (apt.error) /* unsupported case: multiple queues */
1937 cancel = true;
1938 apt.error = 0;
1939 mask = 0;
1940 }
1941 if (mask || apt.error) {
1942 /* Steal to complete synchronously. */
1943 list_del_init(&req->wait.entry);
1944 } else if (cancel) {
1945 /* Cancel if possible (may be too late though). */
1946 WRITE_ONCE(req->cancelled, true);
1947 } else if (on_queue) {
1948 /*
1949 * Actually waiting for an event, so add the request to
1950 * active_reqs so that it can be cancelled if needed.
1951 */
1952 list_add_tail(&aiocb->ki_list, &ctx->active_reqs);
1953 aiocb->ki_cancel = aio_poll_cancel;
1954 }
1955 if (on_queue)
1956 poll_iocb_unlock_wq(req);
1957 }
1958 if (mask) { /* no async, we'd stolen it */
1959 aiocb->ki_res.res = mangle_poll(mask);
1960 apt.error = 0;
1961 }
1962 spin_unlock_irq(&ctx->ctx_lock);
1963 if (mask)
1964 iocb_put(aiocb);
1965 return apt.error;
1966 }
1967
1968 static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
1969 struct iocb __user *user_iocb, struct aio_kiocb *req,
1970 bool compat)
1971 {
1972 req->ki_filp = fget(iocb->aio_fildes);
1973 if (unlikely(!req->ki_filp))
1974 return -EBADF;
1975
1976 if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1977 struct eventfd_ctx *eventfd;
1978 /*
1979 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1980 * instance of the file* now. The file descriptor must be
1981 * an eventfd() fd, and will be signaled for each completed
1982 * event using the eventfd_signal() function.
1983 */
1984 eventfd = eventfd_ctx_fdget(iocb->aio_resfd);
1985 if (IS_ERR(eventfd))
1986 return PTR_ERR(eventfd);
1987
1988 req->ki_eventfd = eventfd;
1989 }
1990
1991 if (unlikely(put_user(KIOCB_KEY, &user_iocb->aio_key))) {
1992 pr_debug("EFAULT: aio_key\n");
1993 return -EFAULT;
1994 }
1995
1996 req->ki_res.obj = (u64)(unsigned long)user_iocb;
1997 req->ki_res.data = iocb->aio_data;
1998 req->ki_res.res = 0;
1999 req->ki_res.res2 = 0;
2000
2001 switch (iocb->aio_lio_opcode) {
2002 case IOCB_CMD_PREAD:
2003 return aio_read(&req->rw, iocb, false, compat);
2004 case IOCB_CMD_PWRITE:
2005 return aio_write(&req->rw, iocb, false, compat);
2006 case IOCB_CMD_PREADV:
2007 return aio_read(&req->rw, iocb, true, compat);
2008 case IOCB_CMD_PWRITEV:
2009 return aio_write(&req->rw, iocb, true, compat);
2010 case IOCB_CMD_FSYNC:
2011 return aio_fsync(&req->fsync, iocb, false);
2012 case IOCB_CMD_FDSYNC:
2013 return aio_fsync(&req->fsync, iocb, true);
2014 case IOCB_CMD_POLL:
2015 return aio_poll(req, iocb);
2016 default:
2017 pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
2018 return -EINVAL;
2019 }
2020 }
2021
2022 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
2023 bool compat)
2024 {
2025 struct aio_kiocb *req;
2026 struct iocb iocb;
2027 int err;
2028
2029 if (unlikely(copy_from_user(&iocb, user_iocb, sizeof(iocb))))
2030 return -EFAULT;
2031
2032 /* enforce forwards compatibility on users */
2033 if (unlikely(iocb.aio_reserved2)) {
2034 pr_debug("EINVAL: reserve field set\n");
2035 return -EINVAL;
2036 }
2037
2038 /* prevent overflows */
2039 if (unlikely(
2040 (iocb.aio_buf != (unsigned long)iocb.aio_buf) ||
2041 (iocb.aio_nbytes != (size_t)iocb.aio_nbytes) ||
2042 ((ssize_t)iocb.aio_nbytes < 0)
2043 )) {
2044 pr_debug("EINVAL: overflow check\n");
2045 return -EINVAL;
2046 }
2047
2048 req = aio_get_req(ctx);
2049 if (unlikely(!req))
2050 return -EAGAIN;
2051
2052 err = __io_submit_one(ctx, &iocb, user_iocb, req, compat);
2053
2054 /* Done with the synchronous reference */
2055 iocb_put(req);
2056
2057 /*
2058 * If err is 0, we'd either done aio_complete() ourselves or have
2059 * arranged for that to be done asynchronously. Anything non-zero
2060 * means that we need to destroy req ourselves.
2061 */
2062 if (unlikely(err)) {
2063 iocb_destroy(req);
2064 put_reqs_available(ctx, 1);
2065 }
2066 return err;
2067 }
2068
2069 /* sys_io_submit:
2070 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
2071 * the number of iocbs queued. May return -EINVAL if the aio_context
2072 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
2073 * *iocbpp[0] is not properly initialized, if the operation specified
2074 * is invalid for the file descriptor in the iocb. May fail with
2075 * -EFAULT if any of the data structures point to invalid data. May
2076 * fail with -EBADF if the file descriptor specified in the first
2077 * iocb is invalid. May fail with -EAGAIN if insufficient resources
2078 * are available to queue any iocbs. Will return 0 if nr is 0. Will
2079 * fail with -ENOSYS if not implemented.
2080 */
2081 SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
2082 struct iocb __user * __user *, iocbpp)
2083 {
2084 struct kioctx *ctx;
2085 long ret = 0;
2086 int i = 0;
2087 struct blk_plug plug;
2088
2089 if (unlikely(nr < 0))
2090 return -EINVAL;
2091
2092 ctx = lookup_ioctx(ctx_id);
2093 if (unlikely(!ctx)) {
2094 pr_debug("EINVAL: invalid context id\n");
2095 return -EINVAL;
2096 }
2097
2098 if (nr > ctx->nr_events)
2099 nr = ctx->nr_events;
2100
2101 if (nr > AIO_PLUG_THRESHOLD)
2102 blk_start_plug(&plug);
2103 for (i = 0; i < nr; i++) {
2104 struct iocb __user *user_iocb;
2105
2106 if (unlikely(get_user(user_iocb, iocbpp + i))) {
2107 ret = -EFAULT;
2108 break;
2109 }
2110
2111 ret = io_submit_one(ctx, user_iocb, false);
2112 if (ret)
2113 break;
2114 }
2115 if (nr > AIO_PLUG_THRESHOLD)
2116 blk_finish_plug(&plug);
2117
2118 percpu_ref_put(&ctx->users);
2119 return i ? i : ret;
2120 }
2121
2122 #ifdef CONFIG_COMPAT
2123 COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
2124 int, nr, compat_uptr_t __user *, iocbpp)
2125 {
2126 struct kioctx *ctx;
2127 long ret = 0;
2128 int i = 0;
2129 struct blk_plug plug;
2130
2131 if (unlikely(nr < 0))
2132 return -EINVAL;
2133
2134 ctx = lookup_ioctx(ctx_id);
2135 if (unlikely(!ctx)) {
2136 pr_debug("EINVAL: invalid context id\n");
2137 return -EINVAL;
2138 }
2139
2140 if (nr > ctx->nr_events)
2141 nr = ctx->nr_events;
2142
2143 if (nr > AIO_PLUG_THRESHOLD)
2144 blk_start_plug(&plug);
2145 for (i = 0; i < nr; i++) {
2146 compat_uptr_t user_iocb;
2147
2148 if (unlikely(get_user(user_iocb, iocbpp + i))) {
2149 ret = -EFAULT;
2150 break;
2151 }
2152
2153 ret = io_submit_one(ctx, compat_ptr(user_iocb), true);
2154 if (ret)
2155 break;
2156 }
2157 if (nr > AIO_PLUG_THRESHOLD)
2158 blk_finish_plug(&plug);
2159
2160 percpu_ref_put(&ctx->users);
2161 return i ? i : ret;
2162 }
2163 #endif
2164
2165 /* sys_io_cancel:
2166 * Attempts to cancel an iocb previously passed to io_submit. If
2167 * the operation is successfully cancelled, the resulting event is
2168 * copied into the memory pointed to by result without being placed
2169 * into the completion queue and 0 is returned. May fail with
2170 * -EFAULT if any of the data structures pointed to are invalid.
2171 * May fail with -EINVAL if aio_context specified by ctx_id is
2172 * invalid. May fail with -EAGAIN if the iocb specified was not
2173 * cancelled. Will fail with -ENOSYS if not implemented.
2174 */
2175 SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
2176 struct io_event __user *, result)
2177 {
2178 struct kioctx *ctx;
2179 struct aio_kiocb *kiocb;
2180 int ret = -EINVAL;
2181 u32 key;
2182 u64 obj = (u64)(unsigned long)iocb;
2183
2184 if (unlikely(get_user(key, &iocb->aio_key)))
2185 return -EFAULT;
2186 if (unlikely(key != KIOCB_KEY))
2187 return -EINVAL;
2188
2189 ctx = lookup_ioctx(ctx_id);
2190 if (unlikely(!ctx))
2191 return -EINVAL;
2192
2193 spin_lock_irq(&ctx->ctx_lock);
2194 /* TODO: use a hash or array, this sucks. */
2195 list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
2196 if (kiocb->ki_res.obj == obj) {
2197 ret = kiocb->ki_cancel(&kiocb->rw);
2198 list_del_init(&kiocb->ki_list);
2199 break;
2200 }
2201 }
2202 spin_unlock_irq(&ctx->ctx_lock);
2203
2204 if (!ret) {
2205 /*
2206 * The result argument is no longer used - the io_event is
2207 * always delivered via the ring buffer. -EINPROGRESS indicates
2208 * cancellation is progress:
2209 */
2210 ret = -EINPROGRESS;
2211 }
2212
2213 percpu_ref_put(&ctx->users);
2214
2215 return ret;
2216 }
2217
2218 static long do_io_getevents(aio_context_t ctx_id,
2219 long min_nr,
2220 long nr,
2221 struct io_event __user *events,
2222 struct timespec64 *ts)
2223 {
2224 ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
2225 struct kioctx *ioctx = lookup_ioctx(ctx_id);
2226 long ret = -EINVAL;
2227
2228 if (likely(ioctx)) {
2229 if (likely(min_nr <= nr && min_nr >= 0))
2230 ret = read_events(ioctx, min_nr, nr, events, until);
2231 percpu_ref_put(&ioctx->users);
2232 }
2233
2234 return ret;
2235 }
2236
2237 /* io_getevents:
2238 * Attempts to read at least min_nr events and up to nr events from
2239 * the completion queue for the aio_context specified by ctx_id. If
2240 * it succeeds, the number of read events is returned. May fail with
2241 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
2242 * out of range, if timeout is out of range. May fail with -EFAULT
2243 * if any of the memory specified is invalid. May return 0 or
2244 * < min_nr if the timeout specified by timeout has elapsed
2245 * before sufficient events are available, where timeout == NULL
2246 * specifies an infinite timeout. Note that the timeout pointed to by
2247 * timeout is relative. Will fail with -ENOSYS if not implemented.
2248 */
2249 #ifdef CONFIG_64BIT
2250
2251 SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
2252 long, min_nr,
2253 long, nr,
2254 struct io_event __user *, events,
2255 struct __kernel_timespec __user *, timeout)
2256 {
2257 struct timespec64 ts;
2258 int ret;
2259
2260 if (timeout && unlikely(get_timespec64(&ts, timeout)))
2261 return -EFAULT;
2262
2263 ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2264 if (!ret && signal_pending(current))
2265 ret = -EINTR;
2266 return ret;
2267 }
2268
2269 #endif
2270
2271 struct __aio_sigset {
2272 const sigset_t __user *sigmask;
2273 size_t sigsetsize;
2274 };
2275
2276 SYSCALL_DEFINE6(io_pgetevents,
2277 aio_context_t, ctx_id,
2278 long, min_nr,
2279 long, nr,
2280 struct io_event __user *, events,
2281 struct __kernel_timespec __user *, timeout,
2282 const struct __aio_sigset __user *, usig)
2283 {
2284 struct __aio_sigset ksig = { NULL, };
2285 struct timespec64 ts;
2286 bool interrupted;
2287 int ret;
2288
2289 if (timeout && unlikely(get_timespec64(&ts, timeout)))
2290 return -EFAULT;
2291
2292 if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2293 return -EFAULT;
2294
2295 ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
2296 if (ret)
2297 return ret;
2298
2299 ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2300
2301 interrupted = signal_pending(current);
2302 restore_saved_sigmask_unless(interrupted);
2303 if (interrupted && !ret)
2304 ret = -ERESTARTNOHAND;
2305
2306 return ret;
2307 }
2308
2309 #if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)
2310
2311 SYSCALL_DEFINE6(io_pgetevents_time32,
2312 aio_context_t, ctx_id,
2313 long, min_nr,
2314 long, nr,
2315 struct io_event __user *, events,
2316 struct old_timespec32 __user *, timeout,
2317 const struct __aio_sigset __user *, usig)
2318 {
2319 struct __aio_sigset ksig = { NULL, };
2320 struct timespec64 ts;
2321 bool interrupted;
2322 int ret;
2323
2324 if (timeout && unlikely(get_old_timespec32(&ts, timeout)))
2325 return -EFAULT;
2326
2327 if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2328 return -EFAULT;
2329
2330
2331 ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
2332 if (ret)
2333 return ret;
2334
2335 ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2336
2337 interrupted = signal_pending(current);
2338 restore_saved_sigmask_unless(interrupted);
2339 if (interrupted && !ret)
2340 ret = -ERESTARTNOHAND;
2341
2342 return ret;
2343 }
2344
2345 #endif
2346
2347 #if defined(CONFIG_COMPAT_32BIT_TIME)
2348
2349 SYSCALL_DEFINE5(io_getevents_time32, __u32, ctx_id,
2350 __s32, min_nr,
2351 __s32, nr,
2352 struct io_event __user *, events,
2353 struct old_timespec32 __user *, timeout)
2354 {
2355 struct timespec64 t;
2356 int ret;
2357
2358 if (timeout && get_old_timespec32(&t, timeout))
2359 return -EFAULT;
2360
2361 ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2362 if (!ret && signal_pending(current))
2363 ret = -EINTR;
2364 return ret;
2365 }
2366
2367 #endif
2368
2369 #ifdef CONFIG_COMPAT
2370
2371 struct __compat_aio_sigset {
2372 compat_uptr_t sigmask;
2373 compat_size_t sigsetsize;
2374 };
2375
2376 #if defined(CONFIG_COMPAT_32BIT_TIME)
2377
2378 COMPAT_SYSCALL_DEFINE6(io_pgetevents,
2379 compat_aio_context_t, ctx_id,
2380 compat_long_t, min_nr,
2381 compat_long_t, nr,
2382 struct io_event __user *, events,
2383 struct old_timespec32 __user *, timeout,
2384 const struct __compat_aio_sigset __user *, usig)
2385 {
2386 struct __compat_aio_sigset ksig = { 0, };
2387 struct timespec64 t;
2388 bool interrupted;
2389 int ret;
2390
2391 if (timeout && get_old_timespec32(&t, timeout))
2392 return -EFAULT;
2393
2394 if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2395 return -EFAULT;
2396
2397 ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
2398 if (ret)
2399 return ret;
2400
2401 ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2402
2403 interrupted = signal_pending(current);
2404 restore_saved_sigmask_unless(interrupted);
2405 if (interrupted && !ret)
2406 ret = -ERESTARTNOHAND;
2407
2408 return ret;
2409 }
2410
2411 #endif
2412
2413 COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64,
2414 compat_aio_context_t, ctx_id,
2415 compat_long_t, min_nr,
2416 compat_long_t, nr,
2417 struct io_event __user *, events,
2418 struct __kernel_timespec __user *, timeout,
2419 const struct __compat_aio_sigset __user *, usig)
2420 {
2421 struct __compat_aio_sigset ksig = { 0, };
2422 struct timespec64 t;
2423 bool interrupted;
2424 int ret;
2425
2426 if (timeout && get_timespec64(&t, timeout))
2427 return -EFAULT;
2428
2429 if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2430 return -EFAULT;
2431
2432 ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
2433 if (ret)
2434 return ret;
2435
2436 ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2437
2438 interrupted = signal_pending(current);
2439 restore_saved_sigmask_unless(interrupted);
2440 if (interrupted && !ret)
2441 ret = -ERESTARTNOHAND;
2442
2443 return ret;
2444 }
2445 #endif
2446
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