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/slab.h>
30 #include <linux/timer.h>
31 #include <linux/aio.h>
32 #include <linux/highmem.h>
33 #include <linux/workqueue.h>
34 #include <linux/security.h>
35 #include <linux/eventfd.h>
36 #include <linux/blkdev.h>
37 #include <linux/compat.h>
38
39 #include <asm/kmap_types.h>
40 #include <asm/uaccess.h>
41
42 #define AIO_RING_MAGIC 0xa10a10a1
43 #define AIO_RING_COMPAT_FEATURES 1
44 #define AIO_RING_INCOMPAT_FEATURES 0
45 struct aio_ring {
46 unsigned id; /* kernel internal index number */
47 unsigned nr; /* number of io_events */
48 unsigned head;
49 unsigned tail;
50
51 unsigned magic;
52 unsigned compat_features;
53 unsigned incompat_features;
54 unsigned header_length; /* size of aio_ring */
55
56
57 struct io_event io_events[0];
58 }; /* 128 bytes + ring size */
59
60 #define AIO_RING_PAGES 8
61
62 struct kioctx {
63 atomic_t users;
64 atomic_t dead;
65
66 /* This needs improving */
67 unsigned long user_id;
68 struct hlist_node list;
69
70 /*
71 * This is what userspace passed to io_setup(), it's not used for
72 * anything but counting against the global max_reqs quota.
73 *
74 * The real limit is nr_events - 1, which will be larger (see
75 * aio_setup_ring())
76 */
77 unsigned max_reqs;
78
79 /* Size of ringbuffer, in units of struct io_event */
80 unsigned nr_events;
81
82 unsigned long mmap_base;
83 unsigned long mmap_size;
84
85 struct page **ring_pages;
86 long nr_pages;
87
88 struct rcu_head rcu_head;
89 struct work_struct rcu_work;
90
91 struct {
92 atomic_t reqs_active;
93 } ____cacheline_aligned_in_smp;
94
95 struct {
96 spinlock_t ctx_lock;
97 struct list_head active_reqs; /* used for cancellation */
98 } ____cacheline_aligned_in_smp;
99
100 struct {
101 struct mutex ring_lock;
102 wait_queue_head_t wait;
103 } ____cacheline_aligned_in_smp;
104
105 struct {
106 unsigned tail;
107 spinlock_t completion_lock;
108 } ____cacheline_aligned_in_smp;
109
110 struct page *internal_pages[AIO_RING_PAGES];
111 };
112
113 /*------ sysctl variables----*/
114 static DEFINE_SPINLOCK(aio_nr_lock);
115 unsigned long aio_nr; /* current system wide number of aio requests */
116 unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
117 /*----end sysctl variables---*/
118
119 static struct kmem_cache *kiocb_cachep;
120 static struct kmem_cache *kioctx_cachep;
121
122 /* aio_setup
123 * Creates the slab caches used by the aio routines, panic on
124 * failure as this is done early during the boot sequence.
125 */
aio_setup(void)126 static int __init aio_setup(void)
127 {
128 kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
129 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
130
131 pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
132
133 return 0;
134 }
135 __initcall(aio_setup);
136
aio_free_ring(struct kioctx * ctx)137 static void aio_free_ring(struct kioctx *ctx)
138 {
139 long i;
140
141 for (i = 0; i < ctx->nr_pages; i++)
142 put_page(ctx->ring_pages[i]);
143
144 if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages)
145 kfree(ctx->ring_pages);
146 }
147
aio_setup_ring(struct kioctx * ctx)148 static int aio_setup_ring(struct kioctx *ctx)
149 {
150 struct aio_ring *ring;
151 unsigned nr_events = ctx->max_reqs;
152 struct mm_struct *mm = current->mm;
153 unsigned long size, populate;
154 int nr_pages;
155
156 /* Compensate for the ring buffer's head/tail overlap entry */
157 nr_events += 2; /* 1 is required, 2 for good luck */
158
159 size = sizeof(struct aio_ring);
160 size += sizeof(struct io_event) * nr_events;
161 nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT;
162
163 if (nr_pages < 0)
164 return -EINVAL;
165
166 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event);
167
168 ctx->nr_events = 0;
169 ctx->ring_pages = ctx->internal_pages;
170 if (nr_pages > AIO_RING_PAGES) {
171 ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
172 GFP_KERNEL);
173 if (!ctx->ring_pages)
174 return -ENOMEM;
175 }
176
177 ctx->mmap_size = nr_pages * PAGE_SIZE;
178 pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
179 down_write(&mm->mmap_sem);
180 ctx->mmap_base = do_mmap_pgoff(NULL, 0, ctx->mmap_size,
181 PROT_READ|PROT_WRITE,
182 MAP_ANONYMOUS|MAP_PRIVATE, 0, &populate);
183 if (IS_ERR((void *)ctx->mmap_base)) {
184 up_write(&mm->mmap_sem);
185 ctx->mmap_size = 0;
186 aio_free_ring(ctx);
187 return -EAGAIN;
188 }
189
190 pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
191 ctx->nr_pages = get_user_pages(current, mm, ctx->mmap_base, nr_pages,
192 1, 0, ctx->ring_pages, NULL);
193 up_write(&mm->mmap_sem);
194
195 if (unlikely(ctx->nr_pages != nr_pages)) {
196 aio_free_ring(ctx);
197 return -EAGAIN;
198 }
199 if (populate)
200 mm_populate(ctx->mmap_base, populate);
201
202 ctx->user_id = ctx->mmap_base;
203 ctx->nr_events = nr_events; /* trusted copy */
204
205 ring = kmap_atomic(ctx->ring_pages[0]);
206 ring->nr = nr_events; /* user copy */
207 ring->id = ctx->user_id;
208 ring->head = ring->tail = 0;
209 ring->magic = AIO_RING_MAGIC;
210 ring->compat_features = AIO_RING_COMPAT_FEATURES;
211 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
212 ring->header_length = sizeof(struct aio_ring);
213 kunmap_atomic(ring);
214 flush_dcache_page(ctx->ring_pages[0]);
215
216 return 0;
217 }
218
219 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
220 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
221 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
222
kiocb_set_cancel_fn(struct kiocb * req,kiocb_cancel_fn * cancel)223 void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel)
224 {
225 struct kioctx *ctx = req->ki_ctx;
226 unsigned long flags;
227
228 spin_lock_irqsave(&ctx->ctx_lock, flags);
229
230 if (!req->ki_list.next)
231 list_add(&req->ki_list, &ctx->active_reqs);
232
233 req->ki_cancel = cancel;
234
235 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
236 }
237 EXPORT_SYMBOL(kiocb_set_cancel_fn);
238
kiocb_cancel(struct kioctx * ctx,struct kiocb * kiocb,struct io_event * res)239 static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb,
240 struct io_event *res)
241 {
242 kiocb_cancel_fn *old, *cancel;
243 int ret = -EINVAL;
244
245 /*
246 * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
247 * actually has a cancel function, hence the cmpxchg()
248 */
249
250 cancel = ACCESS_ONCE(kiocb->ki_cancel);
251 do {
252 if (!cancel || cancel == KIOCB_CANCELLED)
253 return ret;
254
255 old = cancel;
256 cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
257 } while (cancel != old);
258
259 atomic_inc(&kiocb->ki_users);
260 spin_unlock_irq(&ctx->ctx_lock);
261
262 memset(res, 0, sizeof(*res));
263 res->obj = (u64)(unsigned long)kiocb->ki_obj.user;
264 res->data = kiocb->ki_user_data;
265 ret = cancel(kiocb, res);
266
267 spin_lock_irq(&ctx->ctx_lock);
268
269 return ret;
270 }
271
free_ioctx_rcu(struct rcu_head * head)272 static void free_ioctx_rcu(struct rcu_head *head)
273 {
274 struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
275 kmem_cache_free(kioctx_cachep, ctx);
276 }
277
278 /*
279 * When this function runs, the kioctx has been removed from the "hash table"
280 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
281 * now it's safe to cancel any that need to be.
282 */
free_ioctx(struct kioctx * ctx)283 static void free_ioctx(struct kioctx *ctx)
284 {
285 struct aio_ring *ring;
286 struct io_event res;
287 struct kiocb *req;
288 unsigned head, avail;
289
290 spin_lock_irq(&ctx->ctx_lock);
291
292 while (!list_empty(&ctx->active_reqs)) {
293 req = list_first_entry(&ctx->active_reqs,
294 struct kiocb, ki_list);
295
296 list_del_init(&req->ki_list);
297 kiocb_cancel(ctx, req, &res);
298 }
299
300 spin_unlock_irq(&ctx->ctx_lock);
301
302 ring = kmap_atomic(ctx->ring_pages[0]);
303 head = ring->head;
304 kunmap_atomic(ring);
305
306 while (atomic_read(&ctx->reqs_active) > 0) {
307 wait_event(ctx->wait,
308 head != ctx->tail ||
309 atomic_read(&ctx->reqs_active) <= 0);
310
311 avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head;
312
313 atomic_sub(avail, &ctx->reqs_active);
314 head += avail;
315 head %= ctx->nr_events;
316 }
317
318 WARN_ON(atomic_read(&ctx->reqs_active) < 0);
319
320 aio_free_ring(ctx);
321
322 pr_debug("freeing %p\n", ctx);
323
324 /*
325 * Here the call_rcu() is between the wait_event() for reqs_active to
326 * hit 0, and freeing the ioctx.
327 *
328 * aio_complete() decrements reqs_active, but it has to touch the ioctx
329 * after to issue a wakeup so we use rcu.
330 */
331 call_rcu(&ctx->rcu_head, free_ioctx_rcu);
332 }
333
put_ioctx(struct kioctx * ctx)334 static void put_ioctx(struct kioctx *ctx)
335 {
336 if (unlikely(atomic_dec_and_test(&ctx->users)))
337 free_ioctx(ctx);
338 }
339
340 /* ioctx_alloc
341 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
342 */
ioctx_alloc(unsigned nr_events)343 static struct kioctx *ioctx_alloc(unsigned nr_events)
344 {
345 struct mm_struct *mm = current->mm;
346 struct kioctx *ctx;
347 int err = -ENOMEM;
348
349 /* Prevent overflows */
350 if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
351 (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
352 pr_debug("ENOMEM: nr_events too high\n");
353 return ERR_PTR(-EINVAL);
354 }
355
356 if (!nr_events || (unsigned long)nr_events > aio_max_nr)
357 return ERR_PTR(-EAGAIN);
358
359 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
360 if (!ctx)
361 return ERR_PTR(-ENOMEM);
362
363 ctx->max_reqs = nr_events;
364
365 atomic_set(&ctx->users, 2);
366 atomic_set(&ctx->dead, 0);
367 spin_lock_init(&ctx->ctx_lock);
368 spin_lock_init(&ctx->completion_lock);
369 mutex_init(&ctx->ring_lock);
370 init_waitqueue_head(&ctx->wait);
371
372 INIT_LIST_HEAD(&ctx->active_reqs);
373
374 if (aio_setup_ring(ctx) < 0)
375 goto out_freectx;
376
377 /* limit the number of system wide aios */
378 spin_lock(&aio_nr_lock);
379 if (aio_nr + nr_events > aio_max_nr ||
380 aio_nr + nr_events < aio_nr) {
381 spin_unlock(&aio_nr_lock);
382 goto out_cleanup;
383 }
384 aio_nr += ctx->max_reqs;
385 spin_unlock(&aio_nr_lock);
386
387 /* now link into global list. */
388 spin_lock(&mm->ioctx_lock);
389 hlist_add_head_rcu(&ctx->list, &mm->ioctx_list);
390 spin_unlock(&mm->ioctx_lock);
391
392 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
393 ctx, ctx->user_id, mm, ctx->nr_events);
394 return ctx;
395
396 out_cleanup:
397 err = -EAGAIN;
398 aio_free_ring(ctx);
399 out_freectx:
400 kmem_cache_free(kioctx_cachep, ctx);
401 pr_debug("error allocating ioctx %d\n", err);
402 return ERR_PTR(err);
403 }
404
kill_ioctx_work(struct work_struct * work)405 static void kill_ioctx_work(struct work_struct *work)
406 {
407 struct kioctx *ctx = container_of(work, struct kioctx, rcu_work);
408
409 wake_up_all(&ctx->wait);
410 put_ioctx(ctx);
411 }
412
kill_ioctx_rcu(struct rcu_head * head)413 static void kill_ioctx_rcu(struct rcu_head *head)
414 {
415 struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
416
417 INIT_WORK(&ctx->rcu_work, kill_ioctx_work);
418 schedule_work(&ctx->rcu_work);
419 }
420
421 /* kill_ioctx
422 * Cancels all outstanding aio requests on an aio context. Used
423 * when the processes owning a context have all exited to encourage
424 * the rapid destruction of the kioctx.
425 */
kill_ioctx(struct kioctx * ctx)426 static void kill_ioctx(struct kioctx *ctx)
427 {
428 if (!atomic_xchg(&ctx->dead, 1)) {
429 hlist_del_rcu(&ctx->list);
430
431 /*
432 * It'd be more correct to do this in free_ioctx(), after all
433 * the outstanding kiocbs have finished - but by then io_destroy
434 * has already returned, so io_setup() could potentially return
435 * -EAGAIN with no ioctxs actually in use (as far as userspace
436 * could tell).
437 */
438 spin_lock(&aio_nr_lock);
439 BUG_ON(aio_nr - ctx->max_reqs > aio_nr);
440 aio_nr -= ctx->max_reqs;
441 spin_unlock(&aio_nr_lock);
442
443 if (ctx->mmap_size)
444 vm_munmap(ctx->mmap_base, ctx->mmap_size);
445
446 /* Between hlist_del_rcu() and dropping the initial ref */
447 call_rcu(&ctx->rcu_head, kill_ioctx_rcu);
448 }
449 }
450
451 /* wait_on_sync_kiocb:
452 * Waits on the given sync kiocb to complete.
453 */
wait_on_sync_kiocb(struct kiocb * iocb)454 ssize_t wait_on_sync_kiocb(struct kiocb *iocb)
455 {
456 while (atomic_read(&iocb->ki_users)) {
457 set_current_state(TASK_UNINTERRUPTIBLE);
458 if (!atomic_read(&iocb->ki_users))
459 break;
460 io_schedule();
461 }
462 __set_current_state(TASK_RUNNING);
463 return iocb->ki_user_data;
464 }
465 EXPORT_SYMBOL(wait_on_sync_kiocb);
466
467 /*
468 * exit_aio: called when the last user of mm goes away. At this point, there is
469 * no way for any new requests to be submited or any of the io_* syscalls to be
470 * called on the context.
471 *
472 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
473 * them.
474 */
exit_aio(struct mm_struct * mm)475 void exit_aio(struct mm_struct *mm)
476 {
477 struct kioctx *ctx;
478 struct hlist_node *n;
479
480 hlist_for_each_entry_safe(ctx, n, &mm->ioctx_list, list) {
481 if (1 != atomic_read(&ctx->users))
482 printk(KERN_DEBUG
483 "exit_aio:ioctx still alive: %d %d %d\n",
484 atomic_read(&ctx->users),
485 atomic_read(&ctx->dead),
486 atomic_read(&ctx->reqs_active));
487 /*
488 * We don't need to bother with munmap() here -
489 * exit_mmap(mm) is coming and it'll unmap everything.
490 * Since aio_free_ring() uses non-zero ->mmap_size
491 * as indicator that it needs to unmap the area,
492 * just set it to 0; aio_free_ring() is the only
493 * place that uses ->mmap_size, so it's safe.
494 */
495 ctx->mmap_size = 0;
496
497 kill_ioctx(ctx);
498 }
499 }
500
501 /* aio_get_req
502 * Allocate a slot for an aio request. Increments the ki_users count
503 * of the kioctx so that the kioctx stays around until all requests are
504 * complete. Returns NULL if no requests are free.
505 *
506 * Returns with kiocb->ki_users set to 2. The io submit code path holds
507 * an extra reference while submitting the i/o.
508 * This prevents races between the aio code path referencing the
509 * req (after submitting it) and aio_complete() freeing the req.
510 */
aio_get_req(struct kioctx * ctx)511 static inline struct kiocb *aio_get_req(struct kioctx *ctx)
512 {
513 struct kiocb *req;
514
515 if (atomic_read(&ctx->reqs_active) >= ctx->nr_events)
516 return NULL;
517
518 if (atomic_inc_return(&ctx->reqs_active) > ctx->nr_events - 1)
519 goto out_put;
520
521 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
522 if (unlikely(!req))
523 goto out_put;
524
525 atomic_set(&req->ki_users, 2);
526 req->ki_ctx = ctx;
527
528 return req;
529 out_put:
530 atomic_dec(&ctx->reqs_active);
531 return NULL;
532 }
533
kiocb_free(struct kiocb * req)534 static void kiocb_free(struct kiocb *req)
535 {
536 if (req->ki_filp)
537 fput(req->ki_filp);
538 if (req->ki_eventfd != NULL)
539 eventfd_ctx_put(req->ki_eventfd);
540 if (req->ki_dtor)
541 req->ki_dtor(req);
542 if (req->ki_iovec != &req->ki_inline_vec)
543 kfree(req->ki_iovec);
544 kmem_cache_free(kiocb_cachep, req);
545 }
546
aio_put_req(struct kiocb * req)547 void aio_put_req(struct kiocb *req)
548 {
549 if (atomic_dec_and_test(&req->ki_users))
550 kiocb_free(req);
551 }
552 EXPORT_SYMBOL(aio_put_req);
553
lookup_ioctx(unsigned long ctx_id)554 static struct kioctx *lookup_ioctx(unsigned long ctx_id)
555 {
556 struct mm_struct *mm = current->mm;
557 struct kioctx *ctx, *ret = NULL;
558
559 rcu_read_lock();
560
561 hlist_for_each_entry_rcu(ctx, &mm->ioctx_list, list) {
562 if (ctx->user_id == ctx_id) {
563 atomic_inc(&ctx->users);
564 ret = ctx;
565 break;
566 }
567 }
568
569 rcu_read_unlock();
570 return ret;
571 }
572
573 /* aio_complete
574 * Called when the io request on the given iocb is complete.
575 */
aio_complete(struct kiocb * iocb,long res,long res2)576 void aio_complete(struct kiocb *iocb, long res, long res2)
577 {
578 struct kioctx *ctx = iocb->ki_ctx;
579 struct aio_ring *ring;
580 struct io_event *ev_page, *event;
581 unsigned long flags;
582 unsigned tail, pos;
583
584 /*
585 * Special case handling for sync iocbs:
586 * - events go directly into the iocb for fast handling
587 * - the sync task with the iocb in its stack holds the single iocb
588 * ref, no other paths have a way to get another ref
589 * - the sync task helpfully left a reference to itself in the iocb
590 */
591 if (is_sync_kiocb(iocb)) {
592 BUG_ON(atomic_read(&iocb->ki_users) != 1);
593 iocb->ki_user_data = res;
594 atomic_set(&iocb->ki_users, 0);
595 wake_up_process(iocb->ki_obj.tsk);
596 return;
597 }
598
599 /*
600 * Take rcu_read_lock() in case the kioctx is being destroyed, as we
601 * need to issue a wakeup after decrementing reqs_active.
602 */
603 rcu_read_lock();
604
605 if (iocb->ki_list.next) {
606 unsigned long flags;
607
608 spin_lock_irqsave(&ctx->ctx_lock, flags);
609 list_del(&iocb->ki_list);
610 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
611 }
612
613 /*
614 * cancelled requests don't get events, userland was given one
615 * when the event got cancelled.
616 */
617 if (unlikely(xchg(&iocb->ki_cancel,
618 KIOCB_CANCELLED) == KIOCB_CANCELLED)) {
619 atomic_dec(&ctx->reqs_active);
620 /* Still need the wake_up in case free_ioctx is waiting */
621 goto put_rq;
622 }
623
624 /*
625 * Add a completion event to the ring buffer. Must be done holding
626 * ctx->ctx_lock to prevent other code from messing with the tail
627 * pointer since we might be called from irq context.
628 */
629 spin_lock_irqsave(&ctx->completion_lock, flags);
630
631 tail = ctx->tail;
632 pos = tail + AIO_EVENTS_OFFSET;
633
634 if (++tail >= ctx->nr_events)
635 tail = 0;
636
637 ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
638 event = ev_page + pos % AIO_EVENTS_PER_PAGE;
639
640 event->obj = (u64)(unsigned long)iocb->ki_obj.user;
641 event->data = iocb->ki_user_data;
642 event->res = res;
643 event->res2 = res2;
644
645 kunmap_atomic(ev_page);
646 flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
647
648 pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
649 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
650 res, res2);
651
652 /* after flagging the request as done, we
653 * must never even look at it again
654 */
655 smp_wmb(); /* make event visible before updating tail */
656
657 ctx->tail = tail;
658
659 ring = kmap_atomic(ctx->ring_pages[0]);
660 ring->tail = tail;
661 kunmap_atomic(ring);
662 flush_dcache_page(ctx->ring_pages[0]);
663
664 spin_unlock_irqrestore(&ctx->completion_lock, flags);
665
666 pr_debug("added to ring %p at [%u]\n", iocb, tail);
667
668 /*
669 * Check if the user asked us to deliver the result through an
670 * eventfd. The eventfd_signal() function is safe to be called
671 * from IRQ context.
672 */
673 if (iocb->ki_eventfd != NULL)
674 eventfd_signal(iocb->ki_eventfd, 1);
675
676 put_rq:
677 /* everything turned out well, dispose of the aiocb. */
678 aio_put_req(iocb);
679
680 /*
681 * We have to order our ring_info tail store above and test
682 * of the wait list below outside the wait lock. This is
683 * like in wake_up_bit() where clearing a bit has to be
684 * ordered with the unlocked test.
685 */
686 smp_mb();
687
688 if (waitqueue_active(&ctx->wait))
689 wake_up(&ctx->wait);
690
691 rcu_read_unlock();
692 }
693 EXPORT_SYMBOL(aio_complete);
694
695 /* aio_read_events
696 * Pull an event off of the ioctx's event ring. Returns the number of
697 * events fetched
698 */
aio_read_events_ring(struct kioctx * ctx,struct io_event __user * event,long nr)699 static long aio_read_events_ring(struct kioctx *ctx,
700 struct io_event __user *event, long nr)
701 {
702 struct aio_ring *ring;
703 unsigned head, pos;
704 long ret = 0;
705 int copy_ret;
706
707 mutex_lock(&ctx->ring_lock);
708
709 ring = kmap_atomic(ctx->ring_pages[0]);
710 head = ring->head;
711 kunmap_atomic(ring);
712
713 pr_debug("h%u t%u m%u\n", head, ctx->tail, ctx->nr_events);
714
715 if (head == ctx->tail)
716 goto out;
717
718 head %= ctx->nr_events;
719
720 while (ret < nr) {
721 long avail;
722 struct io_event *ev;
723 struct page *page;
724
725 avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head;
726 if (head == ctx->tail)
727 break;
728
729 avail = min(avail, nr - ret);
730 avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
731 ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
732
733 pos = head + AIO_EVENTS_OFFSET;
734 page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
735 pos %= AIO_EVENTS_PER_PAGE;
736
737 ev = kmap(page);
738 copy_ret = copy_to_user(event + ret, ev + pos,
739 sizeof(*ev) * avail);
740 kunmap(page);
741
742 if (unlikely(copy_ret)) {
743 ret = -EFAULT;
744 goto out;
745 }
746
747 ret += avail;
748 head += avail;
749 head %= ctx->nr_events;
750 }
751
752 ring = kmap_atomic(ctx->ring_pages[0]);
753 ring->head = head;
754 kunmap_atomic(ring);
755 flush_dcache_page(ctx->ring_pages[0]);
756
757 pr_debug("%li h%u t%u\n", ret, head, ctx->tail);
758
759 atomic_sub(ret, &ctx->reqs_active);
760 out:
761 mutex_unlock(&ctx->ring_lock);
762
763 return ret;
764 }
765
aio_read_events(struct kioctx * ctx,long min_nr,long nr,struct io_event __user * event,long * i)766 static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
767 struct io_event __user *event, long *i)
768 {
769 long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
770
771 if (ret > 0)
772 *i += ret;
773
774 if (unlikely(atomic_read(&ctx->dead)))
775 ret = -EINVAL;
776
777 if (!*i)
778 *i = ret;
779
780 return ret < 0 || *i >= min_nr;
781 }
782
read_events(struct kioctx * ctx,long min_nr,long nr,struct io_event __user * event,struct timespec __user * timeout)783 static long read_events(struct kioctx *ctx, long min_nr, long nr,
784 struct io_event __user *event,
785 struct timespec __user *timeout)
786 {
787 ktime_t until = { .tv64 = KTIME_MAX };
788 long ret = 0;
789
790 if (timeout) {
791 struct timespec ts;
792
793 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
794 return -EFAULT;
795
796 until = timespec_to_ktime(ts);
797 }
798
799 /*
800 * Note that aio_read_events() is being called as the conditional - i.e.
801 * we're calling it after prepare_to_wait() has set task state to
802 * TASK_INTERRUPTIBLE.
803 *
804 * But aio_read_events() can block, and if it blocks it's going to flip
805 * the task state back to TASK_RUNNING.
806 *
807 * This should be ok, provided it doesn't flip the state back to
808 * TASK_RUNNING and return 0 too much - that causes us to spin. That
809 * will only happen if the mutex_lock() call blocks, and we then find
810 * the ringbuffer empty. So in practice we should be ok, but it's
811 * something to be aware of when touching this code.
812 */
813 wait_event_interruptible_hrtimeout(ctx->wait,
814 aio_read_events(ctx, min_nr, nr, event, &ret), until);
815
816 if (!ret && signal_pending(current))
817 ret = -EINTR;
818
819 return ret;
820 }
821
822 /* sys_io_setup:
823 * Create an aio_context capable of receiving at least nr_events.
824 * ctxp must not point to an aio_context that already exists, and
825 * must be initialized to 0 prior to the call. On successful
826 * creation of the aio_context, *ctxp is filled in with the resulting
827 * handle. May fail with -EINVAL if *ctxp is not initialized,
828 * if the specified nr_events exceeds internal limits. May fail
829 * with -EAGAIN if the specified nr_events exceeds the user's limit
830 * of available events. May fail with -ENOMEM if insufficient kernel
831 * resources are available. May fail with -EFAULT if an invalid
832 * pointer is passed for ctxp. Will fail with -ENOSYS if not
833 * implemented.
834 */
SYSCALL_DEFINE2(io_setup,unsigned,nr_events,aio_context_t __user *,ctxp)835 SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
836 {
837 struct kioctx *ioctx = NULL;
838 unsigned long ctx;
839 long ret;
840
841 ret = get_user(ctx, ctxp);
842 if (unlikely(ret))
843 goto out;
844
845 ret = -EINVAL;
846 if (unlikely(ctx || nr_events == 0)) {
847 pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
848 ctx, nr_events);
849 goto out;
850 }
851
852 ioctx = ioctx_alloc(nr_events);
853 ret = PTR_ERR(ioctx);
854 if (!IS_ERR(ioctx)) {
855 ret = put_user(ioctx->user_id, ctxp);
856 if (ret)
857 kill_ioctx(ioctx);
858 put_ioctx(ioctx);
859 }
860
861 out:
862 return ret;
863 }
864
865 /* sys_io_destroy:
866 * Destroy the aio_context specified. May cancel any outstanding
867 * AIOs and block on completion. Will fail with -ENOSYS if not
868 * implemented. May fail with -EINVAL if the context pointed to
869 * is invalid.
870 */
SYSCALL_DEFINE1(io_destroy,aio_context_t,ctx)871 SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
872 {
873 struct kioctx *ioctx = lookup_ioctx(ctx);
874 if (likely(NULL != ioctx)) {
875 kill_ioctx(ioctx);
876 put_ioctx(ioctx);
877 return 0;
878 }
879 pr_debug("EINVAL: io_destroy: invalid context id\n");
880 return -EINVAL;
881 }
882
aio_advance_iovec(struct kiocb * iocb,ssize_t ret)883 static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret)
884 {
885 struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg];
886
887 BUG_ON(ret <= 0);
888
889 while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) {
890 ssize_t this = min((ssize_t)iov->iov_len, ret);
891 iov->iov_base += this;
892 iov->iov_len -= this;
893 iocb->ki_left -= this;
894 ret -= this;
895 if (iov->iov_len == 0) {
896 iocb->ki_cur_seg++;
897 iov++;
898 }
899 }
900
901 /* the caller should not have done more io than what fit in
902 * the remaining iovecs */
903 BUG_ON(ret > 0 && iocb->ki_left == 0);
904 }
905
906 typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *,
907 unsigned long, loff_t);
908
aio_rw_vect_retry(struct kiocb * iocb,int rw,aio_rw_op * rw_op)909 static ssize_t aio_rw_vect_retry(struct kiocb *iocb, int rw, aio_rw_op *rw_op)
910 {
911 struct file *file = iocb->ki_filp;
912 struct address_space *mapping = file->f_mapping;
913 struct inode *inode = mapping->host;
914 ssize_t ret = 0;
915
916 /* This matches the pread()/pwrite() logic */
917 if (iocb->ki_pos < 0)
918 return -EINVAL;
919
920 if (rw == WRITE)
921 file_start_write(file);
922 do {
923 ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg],
924 iocb->ki_nr_segs - iocb->ki_cur_seg,
925 iocb->ki_pos);
926 if (ret > 0)
927 aio_advance_iovec(iocb, ret);
928
929 /* retry all partial writes. retry partial reads as long as its a
930 * regular file. */
931 } while (ret > 0 && iocb->ki_left > 0 &&
932 (rw == WRITE ||
933 (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))));
934 if (rw == WRITE)
935 file_end_write(file);
936
937 /* This means we must have transferred all that we could */
938 /* No need to retry anymore */
939 if ((ret == 0) || (iocb->ki_left == 0))
940 ret = iocb->ki_nbytes - iocb->ki_left;
941
942 /* If we managed to write some out we return that, rather than
943 * the eventual error. */
944 if (rw == WRITE
945 && ret < 0 && ret != -EIOCBQUEUED
946 && iocb->ki_nbytes - iocb->ki_left)
947 ret = iocb->ki_nbytes - iocb->ki_left;
948
949 return ret;
950 }
951
aio_setup_vectored_rw(int rw,struct kiocb * kiocb,bool compat)952 static ssize_t aio_setup_vectored_rw(int rw, struct kiocb *kiocb, bool compat)
953 {
954 ssize_t ret;
955
956 kiocb->ki_nr_segs = kiocb->ki_nbytes;
957
958 #ifdef CONFIG_COMPAT
959 if (compat)
960 ret = compat_rw_copy_check_uvector(rw,
961 (struct compat_iovec __user *)kiocb->ki_buf,
962 kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec,
963 &kiocb->ki_iovec);
964 else
965 #endif
966 ret = rw_copy_check_uvector(rw,
967 (struct iovec __user *)kiocb->ki_buf,
968 kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec,
969 &kiocb->ki_iovec);
970 if (ret < 0)
971 return ret;
972
973 /* ki_nbytes now reflect bytes instead of segs */
974 kiocb->ki_nbytes = ret;
975 return 0;
976 }
977
aio_setup_single_vector(int rw,struct kiocb * kiocb)978 static ssize_t aio_setup_single_vector(int rw, struct kiocb *kiocb)
979 {
980 size_t len = kiocb->ki_nbytes;
981
982 if (len > MAX_RW_COUNT)
983 len = MAX_RW_COUNT;
984
985 if (unlikely(!access_ok(!rw, kiocb->ki_buf, len)))
986 return -EFAULT;
987
988 kiocb->ki_iovec = &kiocb->ki_inline_vec;
989 kiocb->ki_iovec->iov_base = kiocb->ki_buf;
990 kiocb->ki_iovec->iov_len = len;
991 kiocb->ki_nr_segs = 1;
992 return 0;
993 }
994
995 /*
996 * aio_setup_iocb:
997 * Performs the initial checks and aio retry method
998 * setup for the kiocb at the time of io submission.
999 */
aio_run_iocb(struct kiocb * req,bool compat)1000 static ssize_t aio_run_iocb(struct kiocb *req, bool compat)
1001 {
1002 struct file *file = req->ki_filp;
1003 ssize_t ret;
1004 int rw;
1005 fmode_t mode;
1006 aio_rw_op *rw_op;
1007
1008 switch (req->ki_opcode) {
1009 case IOCB_CMD_PREAD:
1010 case IOCB_CMD_PREADV:
1011 mode = FMODE_READ;
1012 rw = READ;
1013 rw_op = file->f_op->aio_read;
1014 goto rw_common;
1015
1016 case IOCB_CMD_PWRITE:
1017 case IOCB_CMD_PWRITEV:
1018 mode = FMODE_WRITE;
1019 rw = WRITE;
1020 rw_op = file->f_op->aio_write;
1021 goto rw_common;
1022 rw_common:
1023 if (unlikely(!(file->f_mode & mode)))
1024 return -EBADF;
1025
1026 if (!rw_op)
1027 return -EINVAL;
1028
1029 ret = (req->ki_opcode == IOCB_CMD_PREADV ||
1030 req->ki_opcode == IOCB_CMD_PWRITEV)
1031 ? aio_setup_vectored_rw(rw, req, compat)
1032 : aio_setup_single_vector(rw, req);
1033 if (ret)
1034 return ret;
1035
1036 ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
1037 if (ret < 0)
1038 return ret;
1039
1040 req->ki_nbytes = ret;
1041 req->ki_left = ret;
1042
1043 ret = aio_rw_vect_retry(req, rw, rw_op);
1044 break;
1045
1046 case IOCB_CMD_FDSYNC:
1047 if (!file->f_op->aio_fsync)
1048 return -EINVAL;
1049
1050 ret = file->f_op->aio_fsync(req, 1);
1051 break;
1052
1053 case IOCB_CMD_FSYNC:
1054 if (!file->f_op->aio_fsync)
1055 return -EINVAL;
1056
1057 ret = file->f_op->aio_fsync(req, 0);
1058 break;
1059
1060 default:
1061 pr_debug("EINVAL: no operation provided\n");
1062 return -EINVAL;
1063 }
1064
1065 if (ret != -EIOCBQUEUED) {
1066 /*
1067 * There's no easy way to restart the syscall since other AIO's
1068 * may be already running. Just fail this IO with EINTR.
1069 */
1070 if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
1071 ret == -ERESTARTNOHAND ||
1072 ret == -ERESTART_RESTARTBLOCK))
1073 ret = -EINTR;
1074 aio_complete(req, ret, 0);
1075 }
1076
1077 return 0;
1078 }
1079
io_submit_one(struct kioctx * ctx,struct iocb __user * user_iocb,struct iocb * iocb,bool compat)1080 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1081 struct iocb *iocb, bool compat)
1082 {
1083 struct kiocb *req;
1084 ssize_t ret;
1085
1086 /* enforce forwards compatibility on users */
1087 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
1088 pr_debug("EINVAL: reserve field set\n");
1089 return -EINVAL;
1090 }
1091
1092 /* prevent overflows */
1093 if (unlikely(
1094 (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
1095 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
1096 ((ssize_t)iocb->aio_nbytes < 0)
1097 )) {
1098 pr_debug("EINVAL: io_submit: overflow check\n");
1099 return -EINVAL;
1100 }
1101
1102 req = aio_get_req(ctx);
1103 if (unlikely(!req))
1104 return -EAGAIN;
1105
1106 req->ki_filp = fget(iocb->aio_fildes);
1107 if (unlikely(!req->ki_filp)) {
1108 ret = -EBADF;
1109 goto out_put_req;
1110 }
1111
1112 if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1113 /*
1114 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1115 * instance of the file* now. The file descriptor must be
1116 * an eventfd() fd, and will be signaled for each completed
1117 * event using the eventfd_signal() function.
1118 */
1119 req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
1120 if (IS_ERR(req->ki_eventfd)) {
1121 ret = PTR_ERR(req->ki_eventfd);
1122 req->ki_eventfd = NULL;
1123 goto out_put_req;
1124 }
1125 }
1126
1127 ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
1128 if (unlikely(ret)) {
1129 pr_debug("EFAULT: aio_key\n");
1130 goto out_put_req;
1131 }
1132
1133 req->ki_obj.user = user_iocb;
1134 req->ki_user_data = iocb->aio_data;
1135 req->ki_pos = iocb->aio_offset;
1136
1137 req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf;
1138 req->ki_left = req->ki_nbytes = iocb->aio_nbytes;
1139 req->ki_opcode = iocb->aio_lio_opcode;
1140
1141 ret = aio_run_iocb(req, compat);
1142 if (ret)
1143 goto out_put_req;
1144
1145 aio_put_req(req); /* drop extra ref to req */
1146 return 0;
1147 out_put_req:
1148 atomic_dec(&ctx->reqs_active);
1149 aio_put_req(req); /* drop extra ref to req */
1150 aio_put_req(req); /* drop i/o ref to req */
1151 return ret;
1152 }
1153
do_io_submit(aio_context_t ctx_id,long nr,struct iocb __user * __user * iocbpp,bool compat)1154 long do_io_submit(aio_context_t ctx_id, long nr,
1155 struct iocb __user *__user *iocbpp, bool compat)
1156 {
1157 struct kioctx *ctx;
1158 long ret = 0;
1159 int i = 0;
1160 struct blk_plug plug;
1161
1162 if (unlikely(nr < 0))
1163 return -EINVAL;
1164
1165 if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
1166 nr = LONG_MAX/sizeof(*iocbpp);
1167
1168 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1169 return -EFAULT;
1170
1171 ctx = lookup_ioctx(ctx_id);
1172 if (unlikely(!ctx)) {
1173 pr_debug("EINVAL: invalid context id\n");
1174 return -EINVAL;
1175 }
1176
1177 blk_start_plug(&plug);
1178
1179 /*
1180 * AKPM: should this return a partial result if some of the IOs were
1181 * successfully submitted?
1182 */
1183 for (i=0; i<nr; i++) {
1184 struct iocb __user *user_iocb;
1185 struct iocb tmp;
1186
1187 if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1188 ret = -EFAULT;
1189 break;
1190 }
1191
1192 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1193 ret = -EFAULT;
1194 break;
1195 }
1196
1197 ret = io_submit_one(ctx, user_iocb, &tmp, compat);
1198 if (ret)
1199 break;
1200 }
1201 blk_finish_plug(&plug);
1202
1203 put_ioctx(ctx);
1204 return i ? i : ret;
1205 }
1206
1207 /* sys_io_submit:
1208 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1209 * the number of iocbs queued. May return -EINVAL if the aio_context
1210 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1211 * *iocbpp[0] is not properly initialized, if the operation specified
1212 * is invalid for the file descriptor in the iocb. May fail with
1213 * -EFAULT if any of the data structures point to invalid data. May
1214 * fail with -EBADF if the file descriptor specified in the first
1215 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1216 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1217 * fail with -ENOSYS if not implemented.
1218 */
SYSCALL_DEFINE3(io_submit,aio_context_t,ctx_id,long,nr,struct iocb __user * __user *,iocbpp)1219 SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
1220 struct iocb __user * __user *, iocbpp)
1221 {
1222 return do_io_submit(ctx_id, nr, iocbpp, 0);
1223 }
1224
1225 /* lookup_kiocb
1226 * Finds a given iocb for cancellation.
1227 */
lookup_kiocb(struct kioctx * ctx,struct iocb __user * iocb,u32 key)1228 static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
1229 u32 key)
1230 {
1231 struct list_head *pos;
1232
1233 assert_spin_locked(&ctx->ctx_lock);
1234
1235 if (key != KIOCB_KEY)
1236 return NULL;
1237
1238 /* TODO: use a hash or array, this sucks. */
1239 list_for_each(pos, &ctx->active_reqs) {
1240 struct kiocb *kiocb = list_kiocb(pos);
1241 if (kiocb->ki_obj.user == iocb)
1242 return kiocb;
1243 }
1244 return NULL;
1245 }
1246
1247 /* sys_io_cancel:
1248 * Attempts to cancel an iocb previously passed to io_submit. If
1249 * the operation is successfully cancelled, the resulting event is
1250 * copied into the memory pointed to by result without being placed
1251 * into the completion queue and 0 is returned. May fail with
1252 * -EFAULT if any of the data structures pointed to are invalid.
1253 * May fail with -EINVAL if aio_context specified by ctx_id is
1254 * invalid. May fail with -EAGAIN if the iocb specified was not
1255 * cancelled. Will fail with -ENOSYS if not implemented.
1256 */
SYSCALL_DEFINE3(io_cancel,aio_context_t,ctx_id,struct iocb __user *,iocb,struct io_event __user *,result)1257 SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
1258 struct io_event __user *, result)
1259 {
1260 struct io_event res;
1261 struct kioctx *ctx;
1262 struct kiocb *kiocb;
1263 u32 key;
1264 int ret;
1265
1266 ret = get_user(key, &iocb->aio_key);
1267 if (unlikely(ret))
1268 return -EFAULT;
1269
1270 ctx = lookup_ioctx(ctx_id);
1271 if (unlikely(!ctx))
1272 return -EINVAL;
1273
1274 spin_lock_irq(&ctx->ctx_lock);
1275
1276 kiocb = lookup_kiocb(ctx, iocb, key);
1277 if (kiocb)
1278 ret = kiocb_cancel(ctx, kiocb, &res);
1279 else
1280 ret = -EINVAL;
1281
1282 spin_unlock_irq(&ctx->ctx_lock);
1283
1284 if (!ret) {
1285 /* Cancellation succeeded -- copy the result
1286 * into the user's buffer.
1287 */
1288 if (copy_to_user(result, &res, sizeof(res)))
1289 ret = -EFAULT;
1290 }
1291
1292 put_ioctx(ctx);
1293
1294 return ret;
1295 }
1296
1297 /* io_getevents:
1298 * Attempts to read at least min_nr events and up to nr events from
1299 * the completion queue for the aio_context specified by ctx_id. If
1300 * it succeeds, the number of read events is returned. May fail with
1301 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
1302 * out of range, if timeout is out of range. May fail with -EFAULT
1303 * if any of the memory specified is invalid. May return 0 or
1304 * < min_nr if the timeout specified by timeout has elapsed
1305 * before sufficient events are available, where timeout == NULL
1306 * specifies an infinite timeout. Note that the timeout pointed to by
1307 * timeout is relative. Will fail with -ENOSYS if not implemented.
1308 */
SYSCALL_DEFINE5(io_getevents,aio_context_t,ctx_id,long,min_nr,long,nr,struct io_event __user *,events,struct timespec __user *,timeout)1309 SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
1310 long, min_nr,
1311 long, nr,
1312 struct io_event __user *, events,
1313 struct timespec __user *, timeout)
1314 {
1315 struct kioctx *ioctx = lookup_ioctx(ctx_id);
1316 long ret = -EINVAL;
1317
1318 if (likely(ioctx)) {
1319 if (likely(min_nr <= nr && min_nr >= 0))
1320 ret = read_events(ioctx, min_nr, nr, events, timeout);
1321 put_ioctx(ioctx);
1322 }
1323 return ret;
1324 }
1325