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1/*
2 * An async IO implementation for Linux
3 * Written by Benjamin LaHaise <bcrl@kvack.org>
4 *
5 * Implements an efficient asynchronous io interface.
6 *
7 * Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved.
8 *
9 * See ../COPYING for licensing terms.
10 */
11#include <linux/kernel.h>
12#include <linux/init.h>
13#include <linux/errno.h>
14#include <linux/time.h>
15#include <linux/aio_abi.h>
16#include <linux/module.h>
17#include <linux/syscalls.h>
18#include <linux/backing-dev.h>
19#include <linux/uio.h>
20
21#define DEBUG 0
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#if DEBUG > 1
43#define dprintk printk
44#else
45#define dprintk(x...) do { ; } while (0)
46#endif
47
48/*------ sysctl variables----*/
49static DEFINE_SPINLOCK(aio_nr_lock);
50unsigned long aio_nr; /* current system wide number of aio requests */
51unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
52/*----end sysctl variables---*/
53
54static struct kmem_cache *kiocb_cachep;
55static struct kmem_cache *kioctx_cachep;
56
57static struct workqueue_struct *aio_wq;
58
59/* Used for rare fput completion. */
60static void aio_fput_routine(struct work_struct *);
61static DECLARE_WORK(fput_work, aio_fput_routine);
62
63static DEFINE_SPINLOCK(fput_lock);
64static LIST_HEAD(fput_head);
65
66static void aio_kick_handler(struct work_struct *);
67static void aio_queue_work(struct kioctx *);
68
69/* aio_setup
70 * Creates the slab caches used by the aio routines, panic on
71 * failure as this is done early during the boot sequence.
72 */
73static int __init aio_setup(void)
74{
75 kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
76 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
77
78 aio_wq = alloc_workqueue("aio", 0, 1); /* used to limit concurrency */
79 BUG_ON(!aio_wq);
80
81 pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page));
82
83 return 0;
84}
85__initcall(aio_setup);
86
87static void aio_free_ring(struct kioctx *ctx)
88{
89 struct aio_ring_info *info = &ctx->ring_info;
90 long i;
91
92 for (i=0; i<info->nr_pages; i++)
93 put_page(info->ring_pages[i]);
94
95 if (info->mmap_size) {
96 down_write(&ctx->mm->mmap_sem);
97 do_munmap(ctx->mm, info->mmap_base, info->mmap_size);
98 up_write(&ctx->mm->mmap_sem);
99 }
100
101 if (info->ring_pages && info->ring_pages != info->internal_pages)
102 kfree(info->ring_pages);
103 info->ring_pages = NULL;
104 info->nr = 0;
105}
106
107static int aio_setup_ring(struct kioctx *ctx)
108{
109 struct aio_ring *ring;
110 struct aio_ring_info *info = &ctx->ring_info;
111 unsigned nr_events = ctx->max_reqs;
112 unsigned long size;
113 int nr_pages;
114
115 /* Compensate for the ring buffer's head/tail overlap entry */
116 nr_events += 2; /* 1 is required, 2 for good luck */
117
118 size = sizeof(struct aio_ring);
119 size += sizeof(struct io_event) * nr_events;
120 nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT;
121
122 if (nr_pages < 0)
123 return -EINVAL;
124
125 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event);
126
127 info->nr = 0;
128 info->ring_pages = info->internal_pages;
129 if (nr_pages > AIO_RING_PAGES) {
130 info->ring_pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
131 if (!info->ring_pages)
132 return -ENOMEM;
133 }
134
135 info->mmap_size = nr_pages * PAGE_SIZE;
136 dprintk("attempting mmap of %lu bytes\n", info->mmap_size);
137 down_write(&ctx->mm->mmap_sem);
138 info->mmap_base = do_mmap(NULL, 0, info->mmap_size,
139 PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE,
140 0);
141 if (IS_ERR((void *)info->mmap_base)) {
142 up_write(&ctx->mm->mmap_sem);
143 info->mmap_size = 0;
144 aio_free_ring(ctx);
145 return -EAGAIN;
146 }
147
148 dprintk("mmap address: 0x%08lx\n", info->mmap_base);
149 info->nr_pages = get_user_pages(current, ctx->mm,
150 info->mmap_base, nr_pages,
151 1, 0, info->ring_pages, NULL);
152 up_write(&ctx->mm->mmap_sem);
153
154 if (unlikely(info->nr_pages != nr_pages)) {
155 aio_free_ring(ctx);
156 return -EAGAIN;
157 }
158
159 ctx->user_id = info->mmap_base;
160
161 info->nr = nr_events; /* trusted copy */
162
163 ring = kmap_atomic(info->ring_pages[0], KM_USER0);
164 ring->nr = nr_events; /* user copy */
165 ring->id = ctx->user_id;
166 ring->head = ring->tail = 0;
167 ring->magic = AIO_RING_MAGIC;
168 ring->compat_features = AIO_RING_COMPAT_FEATURES;
169 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
170 ring->header_length = sizeof(struct aio_ring);
171 kunmap_atomic(ring, KM_USER0);
172
173 return 0;
174}
175
176
177/* aio_ring_event: returns a pointer to the event at the given index from
178 * kmap_atomic(, km). Release the pointer with put_aio_ring_event();
179 */
180#define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
181#define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
182#define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
183
184#define aio_ring_event(info, nr, km) ({ \
185 unsigned pos = (nr) + AIO_EVENTS_OFFSET; \
186 struct io_event *__event; \
187 __event = kmap_atomic( \
188 (info)->ring_pages[pos / AIO_EVENTS_PER_PAGE], km); \
189 __event += pos % AIO_EVENTS_PER_PAGE; \
190 __event; \
191})
192
193#define put_aio_ring_event(event, km) do { \
194 struct io_event *__event = (event); \
195 (void)__event; \
196 kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK), km); \
197} while(0)
198
199static void ctx_rcu_free(struct rcu_head *head)
200{
201 struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
202 unsigned nr_events = ctx->max_reqs;
203
204 kmem_cache_free(kioctx_cachep, ctx);
205
206 if (nr_events) {
207 spin_lock(&aio_nr_lock);
208 BUG_ON(aio_nr - nr_events > aio_nr);
209 aio_nr -= nr_events;
210 spin_unlock(&aio_nr_lock);
211 }
212}
213
214/* __put_ioctx
215 * Called when the last user of an aio context has gone away,
216 * and the struct needs to be freed.
217 */
218static void __put_ioctx(struct kioctx *ctx)
219{
220 BUG_ON(ctx->reqs_active);
221
222 cancel_delayed_work(&ctx->wq);
223 cancel_work_sync(&ctx->wq.work);
224 aio_free_ring(ctx);
225 mmdrop(ctx->mm);
226 ctx->mm = NULL;
227 pr_debug("__put_ioctx: freeing %p\n", ctx);
228 call_rcu(&ctx->rcu_head, ctx_rcu_free);
229}
230
231static inline void get_ioctx(struct kioctx *kioctx)
232{
233 BUG_ON(atomic_read(&kioctx->users) <= 0);
234 atomic_inc(&kioctx->users);
235}
236
237static inline int try_get_ioctx(struct kioctx *kioctx)
238{
239 return atomic_inc_not_zero(&kioctx->users);
240}
241
242static inline void put_ioctx(struct kioctx *kioctx)
243{
244 BUG_ON(atomic_read(&kioctx->users) <= 0);
245 if (unlikely(atomic_dec_and_test(&kioctx->users)))
246 __put_ioctx(kioctx);
247}
248
249/* ioctx_alloc
250 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
251 */
252static struct kioctx *ioctx_alloc(unsigned nr_events)
253{
254 struct mm_struct *mm;
255 struct kioctx *ctx;
256 int did_sync = 0;
257
258 /* Prevent overflows */
259 if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
260 (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
261 pr_debug("ENOMEM: nr_events too high\n");
262 return ERR_PTR(-EINVAL);
263 }
264
265 if ((unsigned long)nr_events > aio_max_nr)
266 return ERR_PTR(-EAGAIN);
267
268 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
269 if (!ctx)
270 return ERR_PTR(-ENOMEM);
271
272 ctx->max_reqs = nr_events;
273 mm = ctx->mm = current->mm;
274 atomic_inc(&mm->mm_count);
275
276 atomic_set(&ctx->users, 1);
277 spin_lock_init(&ctx->ctx_lock);
278 spin_lock_init(&ctx->ring_info.ring_lock);
279 init_waitqueue_head(&ctx->wait);
280
281 INIT_LIST_HEAD(&ctx->active_reqs);
282 INIT_LIST_HEAD(&ctx->run_list);
283 INIT_DELAYED_WORK(&ctx->wq, aio_kick_handler);
284
285 if (aio_setup_ring(ctx) < 0)
286 goto out_freectx;
287
288 /* limit the number of system wide aios */
289 do {
290 spin_lock_bh(&aio_nr_lock);
291 if (aio_nr + nr_events > aio_max_nr ||
292 aio_nr + nr_events < aio_nr)
293 ctx->max_reqs = 0;
294 else
295 aio_nr += ctx->max_reqs;
296 spin_unlock_bh(&aio_nr_lock);
297 if (ctx->max_reqs || did_sync)
298 break;
299
300 /* wait for rcu callbacks to have completed before giving up */
301 synchronize_rcu();
302 did_sync = 1;
303 ctx->max_reqs = nr_events;
304 } while (1);
305
306 if (ctx->max_reqs == 0)
307 goto out_cleanup;
308
309 /* now link into global list. */
310 spin_lock(&mm->ioctx_lock);
311 hlist_add_head_rcu(&ctx->list, &mm->ioctx_list);
312 spin_unlock(&mm->ioctx_lock);
313
314 dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
315 ctx, ctx->user_id, current->mm, ctx->ring_info.nr);
316 return ctx;
317
318out_cleanup:
319 __put_ioctx(ctx);
320 return ERR_PTR(-EAGAIN);
321
322out_freectx:
323 mmdrop(mm);
324 kmem_cache_free(kioctx_cachep, ctx);
325 ctx = ERR_PTR(-ENOMEM);
326
327 dprintk("aio: error allocating ioctx %p\n", ctx);
328 return ctx;
329}
330
331/* aio_cancel_all
332 * Cancels all outstanding aio requests on an aio context. Used
333 * when the processes owning a context have all exited to encourage
334 * the rapid destruction of the kioctx.
335 */
336static void aio_cancel_all(struct kioctx *ctx)
337{
338 int (*cancel)(struct kiocb *, struct io_event *);
339 struct io_event res;
340 spin_lock_irq(&ctx->ctx_lock);
341 ctx->dead = 1;
342 while (!list_empty(&ctx->active_reqs)) {
343 struct list_head *pos = ctx->active_reqs.next;
344 struct kiocb *iocb = list_kiocb(pos);
345 list_del_init(&iocb->ki_list);
346 cancel = iocb->ki_cancel;
347 kiocbSetCancelled(iocb);
348 if (cancel) {
349 iocb->ki_users++;
350 spin_unlock_irq(&ctx->ctx_lock);
351 cancel(iocb, &res);
352 spin_lock_irq(&ctx->ctx_lock);
353 }
354 }
355 spin_unlock_irq(&ctx->ctx_lock);
356}
357
358static void wait_for_all_aios(struct kioctx *ctx)
359{
360 struct task_struct *tsk = current;
361 DECLARE_WAITQUEUE(wait, tsk);
362
363 spin_lock_irq(&ctx->ctx_lock);
364 if (!ctx->reqs_active)
365 goto out;
366
367 add_wait_queue(&ctx->wait, &wait);
368 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
369 while (ctx->reqs_active) {
370 spin_unlock_irq(&ctx->ctx_lock);
371 io_schedule();
372 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
373 spin_lock_irq(&ctx->ctx_lock);
374 }
375 __set_task_state(tsk, TASK_RUNNING);
376 remove_wait_queue(&ctx->wait, &wait);
377
378out:
379 spin_unlock_irq(&ctx->ctx_lock);
380}
381
382/* wait_on_sync_kiocb:
383 * Waits on the given sync kiocb to complete.
384 */
385ssize_t wait_on_sync_kiocb(struct kiocb *iocb)
386{
387 while (iocb->ki_users) {
388 set_current_state(TASK_UNINTERRUPTIBLE);
389 if (!iocb->ki_users)
390 break;
391 io_schedule();
392 }
393 __set_current_state(TASK_RUNNING);
394 return iocb->ki_user_data;
395}
396EXPORT_SYMBOL(wait_on_sync_kiocb);
397
398/* exit_aio: called when the last user of mm goes away. At this point,
399 * there is no way for any new requests to be submited or any of the
400 * io_* syscalls to be called on the context. However, there may be
401 * outstanding requests which hold references to the context; as they
402 * go away, they will call put_ioctx and release any pinned memory
403 * associated with the request (held via struct page * references).
404 */
405void exit_aio(struct mm_struct *mm)
406{
407 struct kioctx *ctx;
408
409 while (!hlist_empty(&mm->ioctx_list)) {
410 ctx = hlist_entry(mm->ioctx_list.first, struct kioctx, list);
411 hlist_del_rcu(&ctx->list);
412
413 aio_cancel_all(ctx);
414
415 wait_for_all_aios(ctx);
416 /*
417 * Ensure we don't leave the ctx on the aio_wq
418 */
419 cancel_work_sync(&ctx->wq.work);
420
421 if (1 != atomic_read(&ctx->users))
422 printk(KERN_DEBUG
423 "exit_aio:ioctx still alive: %d %d %d\n",
424 atomic_read(&ctx->users), ctx->dead,
425 ctx->reqs_active);
426 put_ioctx(ctx);
427 }
428}
429
430/* aio_get_req
431 * Allocate a slot for an aio request. Increments the users count
432 * of the kioctx so that the kioctx stays around until all requests are
433 * complete. Returns NULL if no requests are free.
434 *
435 * Returns with kiocb->users set to 2. The io submit code path holds
436 * an extra reference while submitting the i/o.
437 * This prevents races between the aio code path referencing the
438 * req (after submitting it) and aio_complete() freeing the req.
439 */
440static struct kiocb *__aio_get_req(struct kioctx *ctx)
441{
442 struct kiocb *req = NULL;
443 struct aio_ring *ring;
444 int okay = 0;
445
446 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
447 if (unlikely(!req))
448 return NULL;
449
450 req->ki_flags = 0;
451 req->ki_users = 2;
452 req->ki_key = 0;
453 req->ki_ctx = ctx;
454 req->ki_cancel = NULL;
455 req->ki_retry = NULL;
456 req->ki_dtor = NULL;
457 req->private = NULL;
458 req->ki_iovec = NULL;
459 INIT_LIST_HEAD(&req->ki_run_list);
460 req->ki_eventfd = NULL;
461
462 /* Check if the completion queue has enough free space to
463 * accept an event from this io.
464 */
465 spin_lock_irq(&ctx->ctx_lock);
466 ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0);
467 if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) {
468 list_add(&req->ki_list, &ctx->active_reqs);
469 ctx->reqs_active++;
470 okay = 1;
471 }
472 kunmap_atomic(ring, KM_USER0);
473 spin_unlock_irq(&ctx->ctx_lock);
474
475 if (!okay) {
476 kmem_cache_free(kiocb_cachep, req);
477 req = NULL;
478 }
479
480 return req;
481}
482
483static inline struct kiocb *aio_get_req(struct kioctx *ctx)
484{
485 struct kiocb *req;
486 /* Handle a potential starvation case -- should be exceedingly rare as
487 * requests will be stuck on fput_head only if the aio_fput_routine is
488 * delayed and the requests were the last user of the struct file.
489 */
490 req = __aio_get_req(ctx);
491 if (unlikely(NULL == req)) {
492 aio_fput_routine(NULL);
493 req = __aio_get_req(ctx);
494 }
495 return req;
496}
497
498static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
499{
500 assert_spin_locked(&ctx->ctx_lock);
501
502 if (req->ki_eventfd != NULL)
503 eventfd_ctx_put(req->ki_eventfd);
504 if (req->ki_dtor)
505 req->ki_dtor(req);
506 if (req->ki_iovec != &req->ki_inline_vec)
507 kfree(req->ki_iovec);
508 kmem_cache_free(kiocb_cachep, req);
509 ctx->reqs_active--;
510
511 if (unlikely(!ctx->reqs_active && ctx->dead))
512 wake_up_all(&ctx->wait);
513}
514
515static void aio_fput_routine(struct work_struct *data)
516{
517 spin_lock_irq(&fput_lock);
518 while (likely(!list_empty(&fput_head))) {
519 struct kiocb *req = list_kiocb(fput_head.next);
520 struct kioctx *ctx = req->ki_ctx;
521
522 list_del(&req->ki_list);
523 spin_unlock_irq(&fput_lock);
524
525 /* Complete the fput(s) */
526 if (req->ki_filp != NULL)
527 fput(req->ki_filp);
528
529 /* Link the iocb into the context's free list */
530 spin_lock_irq(&ctx->ctx_lock);
531 really_put_req(ctx, req);
532 spin_unlock_irq(&ctx->ctx_lock);
533
534 put_ioctx(ctx);
535 spin_lock_irq(&fput_lock);
536 }
537 spin_unlock_irq(&fput_lock);
538}
539
540/* __aio_put_req
541 * Returns true if this put was the last user of the request.
542 */
543static int __aio_put_req(struct kioctx *ctx, struct kiocb *req)
544{
545 dprintk(KERN_DEBUG "aio_put(%p): f_count=%ld\n",
546 req, atomic_long_read(&req->ki_filp->f_count));
547
548 assert_spin_locked(&ctx->ctx_lock);
549
550 req->ki_users--;
551 BUG_ON(req->ki_users < 0);
552 if (likely(req->ki_users))
553 return 0;
554 list_del(&req->ki_list); /* remove from active_reqs */
555 req->ki_cancel = NULL;
556 req->ki_retry = NULL;
557
558 /*
559 * Try to optimize the aio and eventfd file* puts, by avoiding to
560 * schedule work in case it is not final fput() time. In normal cases,
561 * we would not be holding the last reference to the file*, so
562 * this function will be executed w/out any aio kthread wakeup.
563 */
564 if (unlikely(!fput_atomic(req->ki_filp))) {
565 get_ioctx(ctx);
566 spin_lock(&fput_lock);
567 list_add(&req->ki_list, &fput_head);
568 spin_unlock(&fput_lock);
569 schedule_work(&fput_work);
570 } else {
571 req->ki_filp = NULL;
572 really_put_req(ctx, req);
573 }
574 return 1;
575}
576
577/* aio_put_req
578 * Returns true if this put was the last user of the kiocb,
579 * false if the request is still in use.
580 */
581int aio_put_req(struct kiocb *req)
582{
583 struct kioctx *ctx = req->ki_ctx;
584 int ret;
585 spin_lock_irq(&ctx->ctx_lock);
586 ret = __aio_put_req(ctx, req);
587 spin_unlock_irq(&ctx->ctx_lock);
588 return ret;
589}
590EXPORT_SYMBOL(aio_put_req);
591
592static struct kioctx *lookup_ioctx(unsigned long ctx_id)
593{
594 struct mm_struct *mm = current->mm;
595 struct kioctx *ctx, *ret = NULL;
596 struct hlist_node *n;
597
598 rcu_read_lock();
599
600 hlist_for_each_entry_rcu(ctx, n, &mm->ioctx_list, list) {
601 /*
602 * RCU protects us against accessing freed memory but
603 * we have to be careful not to get a reference when the
604 * reference count already dropped to 0 (ctx->dead test
605 * is unreliable because of races).
606 */
607 if (ctx->user_id == ctx_id && !ctx->dead && try_get_ioctx(ctx)){
608 ret = ctx;
609 break;
610 }
611 }
612
613 rcu_read_unlock();
614 return ret;
615}
616
617/*
618 * Queue up a kiocb to be retried. Assumes that the kiocb
619 * has already been marked as kicked, and places it on
620 * the retry run list for the corresponding ioctx, if it
621 * isn't already queued. Returns 1 if it actually queued
622 * the kiocb (to tell the caller to activate the work
623 * queue to process it), or 0, if it found that it was
624 * already queued.
625 */
626static inline int __queue_kicked_iocb(struct kiocb *iocb)
627{
628 struct kioctx *ctx = iocb->ki_ctx;
629
630 assert_spin_locked(&ctx->ctx_lock);
631
632 if (list_empty(&iocb->ki_run_list)) {
633 list_add_tail(&iocb->ki_run_list,
634 &ctx->run_list);
635 return 1;
636 }
637 return 0;
638}
639
640/* aio_run_iocb
641 * This is the core aio execution routine. It is
642 * invoked both for initial i/o submission and
643 * subsequent retries via the aio_kick_handler.
644 * Expects to be invoked with iocb->ki_ctx->lock
645 * already held. The lock is released and reacquired
646 * as needed during processing.
647 *
648 * Calls the iocb retry method (already setup for the
649 * iocb on initial submission) for operation specific
650 * handling, but takes care of most of common retry
651 * execution details for a given iocb. The retry method
652 * needs to be non-blocking as far as possible, to avoid
653 * holding up other iocbs waiting to be serviced by the
654 * retry kernel thread.
655 *
656 * The trickier parts in this code have to do with
657 * ensuring that only one retry instance is in progress
658 * for a given iocb at any time. Providing that guarantee
659 * simplifies the coding of individual aio operations as
660 * it avoids various potential races.
661 */
662static ssize_t aio_run_iocb(struct kiocb *iocb)
663{
664 struct kioctx *ctx = iocb->ki_ctx;
665 ssize_t (*retry)(struct kiocb *);
666 ssize_t ret;
667
668 if (!(retry = iocb->ki_retry)) {
669 printk("aio_run_iocb: iocb->ki_retry = NULL\n");
670 return 0;
671 }
672
673 /*
674 * We don't want the next retry iteration for this
675 * operation to start until this one has returned and
676 * updated the iocb state. However, wait_queue functions
677 * can trigger a kick_iocb from interrupt context in the
678 * meantime, indicating that data is available for the next
679 * iteration. We want to remember that and enable the
680 * next retry iteration _after_ we are through with
681 * this one.
682 *
683 * So, in order to be able to register a "kick", but
684 * prevent it from being queued now, we clear the kick
685 * flag, but make the kick code *think* that the iocb is
686 * still on the run list until we are actually done.
687 * When we are done with this iteration, we check if
688 * the iocb was kicked in the meantime and if so, queue
689 * it up afresh.
690 */
691
692 kiocbClearKicked(iocb);
693
694 /*
695 * This is so that aio_complete knows it doesn't need to
696 * pull the iocb off the run list (We can't just call
697 * INIT_LIST_HEAD because we don't want a kick_iocb to
698 * queue this on the run list yet)
699 */
700 iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL;
701 spin_unlock_irq(&ctx->ctx_lock);
702
703 /* Quit retrying if the i/o has been cancelled */
704 if (kiocbIsCancelled(iocb)) {
705 ret = -EINTR;
706 aio_complete(iocb, ret, 0);
707 /* must not access the iocb after this */
708 goto out;
709 }
710
711 /*
712 * Now we are all set to call the retry method in async
713 * context.
714 */
715 ret = retry(iocb);
716
717 if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) {
718 /*
719 * There's no easy way to restart the syscall since other AIO's
720 * may be already running. Just fail this IO with EINTR.
721 */
722 if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
723 ret == -ERESTARTNOHAND || ret == -ERESTART_RESTARTBLOCK))
724 ret = -EINTR;
725 aio_complete(iocb, ret, 0);
726 }
727out:
728 spin_lock_irq(&ctx->ctx_lock);
729
730 if (-EIOCBRETRY == ret) {
731 /*
732 * OK, now that we are done with this iteration
733 * and know that there is more left to go,
734 * this is where we let go so that a subsequent
735 * "kick" can start the next iteration
736 */
737
738 /* will make __queue_kicked_iocb succeed from here on */
739 INIT_LIST_HEAD(&iocb->ki_run_list);
740 /* we must queue the next iteration ourselves, if it
741 * has already been kicked */
742 if (kiocbIsKicked(iocb)) {
743 __queue_kicked_iocb(iocb);
744
745 /*
746 * __queue_kicked_iocb will always return 1 here, because
747 * iocb->ki_run_list is empty at this point so it should
748 * be safe to unconditionally queue the context into the
749 * work queue.
750 */
751 aio_queue_work(ctx);
752 }
753 }
754 return ret;
755}
756
757/*
758 * __aio_run_iocbs:
759 * Process all pending retries queued on the ioctx
760 * run list.
761 * Assumes it is operating within the aio issuer's mm
762 * context.
763 */
764static int __aio_run_iocbs(struct kioctx *ctx)
765{
766 struct kiocb *iocb;
767 struct list_head run_list;
768
769 assert_spin_locked(&ctx->ctx_lock);
770
771 list_replace_init(&ctx->run_list, &run_list);
772 while (!list_empty(&run_list)) {
773 iocb = list_entry(run_list.next, struct kiocb,
774 ki_run_list);
775 list_del(&iocb->ki_run_list);
776 /*
777 * Hold an extra reference while retrying i/o.
778 */
779 iocb->ki_users++; /* grab extra reference */
780 aio_run_iocb(iocb);
781 __aio_put_req(ctx, iocb);
782 }
783 if (!list_empty(&ctx->run_list))
784 return 1;
785 return 0;
786}
787
788static void aio_queue_work(struct kioctx * ctx)
789{
790 unsigned long timeout;
791 /*
792 * if someone is waiting, get the work started right
793 * away, otherwise, use a longer delay
794 */
795 smp_mb();
796 if (waitqueue_active(&ctx->wait))
797 timeout = 1;
798 else
799 timeout = HZ/10;
800 queue_delayed_work(aio_wq, &ctx->wq, timeout);
801}
802
803/*
804 * aio_run_all_iocbs:
805 * Process all pending retries queued on the ioctx
806 * run list, and keep running them until the list
807 * stays empty.
808 * Assumes it is operating within the aio issuer's mm context.
809 */
810static inline void aio_run_all_iocbs(struct kioctx *ctx)
811{
812 spin_lock_irq(&ctx->ctx_lock);
813 while (__aio_run_iocbs(ctx))
814 ;
815 spin_unlock_irq(&ctx->ctx_lock);
816}
817
818/*
819 * aio_kick_handler:
820 * Work queue handler triggered to process pending
821 * retries on an ioctx. Takes on the aio issuer's
822 * mm context before running the iocbs, so that
823 * copy_xxx_user operates on the issuer's address
824 * space.
825 * Run on aiod's context.
826 */
827static void aio_kick_handler(struct work_struct *work)
828{
829 struct kioctx *ctx = container_of(work, struct kioctx, wq.work);
830 mm_segment_t oldfs = get_fs();
831 struct mm_struct *mm;
832 int requeue;
833
834 set_fs(USER_DS);
835 use_mm(ctx->mm);
836 spin_lock_irq(&ctx->ctx_lock);
837 requeue =__aio_run_iocbs(ctx);
838 mm = ctx->mm;
839 spin_unlock_irq(&ctx->ctx_lock);
840 unuse_mm(mm);
841 set_fs(oldfs);
842 /*
843 * we're in a worker thread already, don't use queue_delayed_work,
844 */
845 if (requeue)
846 queue_delayed_work(aio_wq, &ctx->wq, 0);
847}
848
849
850/*
851 * Called by kick_iocb to queue the kiocb for retry
852 * and if required activate the aio work queue to process
853 * it
854 */
855static void try_queue_kicked_iocb(struct kiocb *iocb)
856{
857 struct kioctx *ctx = iocb->ki_ctx;
858 unsigned long flags;
859 int run = 0;
860
861 spin_lock_irqsave(&ctx->ctx_lock, flags);
862 /* set this inside the lock so that we can't race with aio_run_iocb()
863 * testing it and putting the iocb on the run list under the lock */
864 if (!kiocbTryKick(iocb))
865 run = __queue_kicked_iocb(iocb);
866 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
867 if (run)
868 aio_queue_work(ctx);
869}
870
871/*
872 * kick_iocb:
873 * Called typically from a wait queue callback context
874 * to trigger a retry of the iocb.
875 * The retry is usually executed by aio workqueue
876 * threads (See aio_kick_handler).
877 */
878void kick_iocb(struct kiocb *iocb)
879{
880 /* sync iocbs are easy: they can only ever be executing from a
881 * single context. */
882 if (is_sync_kiocb(iocb)) {
883 kiocbSetKicked(iocb);
884 wake_up_process(iocb->ki_obj.tsk);
885 return;
886 }
887
888 try_queue_kicked_iocb(iocb);
889}
890EXPORT_SYMBOL(kick_iocb);
891
892/* aio_complete
893 * Called when the io request on the given iocb is complete.
894 * Returns true if this is the last user of the request. The
895 * only other user of the request can be the cancellation code.
896 */
897int aio_complete(struct kiocb *iocb, long res, long res2)
898{
899 struct kioctx *ctx = iocb->ki_ctx;
900 struct aio_ring_info *info;
901 struct aio_ring *ring;
902 struct io_event *event;
903 unsigned long flags;
904 unsigned long tail;
905 int ret;
906
907 /*
908 * Special case handling for sync iocbs:
909 * - events go directly into the iocb for fast handling
910 * - the sync task with the iocb in its stack holds the single iocb
911 * ref, no other paths have a way to get another ref
912 * - the sync task helpfully left a reference to itself in the iocb
913 */
914 if (is_sync_kiocb(iocb)) {
915 BUG_ON(iocb->ki_users != 1);
916 iocb->ki_user_data = res;
917 iocb->ki_users = 0;
918 wake_up_process(iocb->ki_obj.tsk);
919 return 1;
920 }
921
922 info = &ctx->ring_info;
923
924 /* add a completion event to the ring buffer.
925 * must be done holding ctx->ctx_lock to prevent
926 * other code from messing with the tail
927 * pointer since we might be called from irq
928 * context.
929 */
930 spin_lock_irqsave(&ctx->ctx_lock, flags);
931
932 if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list))
933 list_del_init(&iocb->ki_run_list);
934
935 /*
936 * cancelled requests don't get events, userland was given one
937 * when the event got cancelled.
938 */
939 if (kiocbIsCancelled(iocb))
940 goto put_rq;
941
942 ring = kmap_atomic(info->ring_pages[0], KM_IRQ1);
943
944 tail = info->tail;
945 event = aio_ring_event(info, tail, KM_IRQ0);
946 if (++tail >= info->nr)
947 tail = 0;
948
949 event->obj = (u64)(unsigned long)iocb->ki_obj.user;
950 event->data = iocb->ki_user_data;
951 event->res = res;
952 event->res2 = res2;
953
954 dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n",
955 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
956 res, res2);
957
958 /* after flagging the request as done, we
959 * must never even look at it again
960 */
961 smp_wmb(); /* make event visible before updating tail */
962
963 info->tail = tail;
964 ring->tail = tail;
965
966 put_aio_ring_event(event, KM_IRQ0);
967 kunmap_atomic(ring, KM_IRQ1);
968
969 pr_debug("added to ring %p at [%lu]\n", iocb, tail);
970
971 /*
972 * Check if the user asked us to deliver the result through an
973 * eventfd. The eventfd_signal() function is safe to be called
974 * from IRQ context.
975 */
976 if (iocb->ki_eventfd != NULL)
977 eventfd_signal(iocb->ki_eventfd, 1);
978
979put_rq:
980 /* everything turned out well, dispose of the aiocb. */
981 ret = __aio_put_req(ctx, iocb);
982
983 /*
984 * We have to order our ring_info tail store above and test
985 * of the wait list below outside the wait lock. This is
986 * like in wake_up_bit() where clearing a bit has to be
987 * ordered with the unlocked test.
988 */
989 smp_mb();
990
991 if (waitqueue_active(&ctx->wait))
992 wake_up(&ctx->wait);
993
994 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
995 return ret;
996}
997EXPORT_SYMBOL(aio_complete);
998
999/* aio_read_evt
1000 * Pull an event off of the ioctx's event ring. Returns the number of
1001 * events fetched (0 or 1 ;-)
1002 * FIXME: make this use cmpxchg.
1003 * TODO: make the ringbuffer user mmap()able (requires FIXME).
1004 */
1005static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent)
1006{
1007 struct aio_ring_info *info = &ioctx->ring_info;
1008 struct aio_ring *ring;
1009 unsigned long head;
1010 int ret = 0;
1011
1012 ring = kmap_atomic(info->ring_pages[0], KM_USER0);
1013 dprintk("in aio_read_evt h%lu t%lu m%lu\n",
1014 (unsigned long)ring->head, (unsigned long)ring->tail,
1015 (unsigned long)ring->nr);
1016
1017 if (ring->head == ring->tail)
1018 goto out;
1019
1020 spin_lock(&info->ring_lock);
1021
1022 head = ring->head % info->nr;
1023 if (head != ring->tail) {
1024 struct io_event *evp = aio_ring_event(info, head, KM_USER1);
1025 *ent = *evp;
1026 head = (head + 1) % info->nr;
1027 smp_mb(); /* finish reading the event before updatng the head */
1028 ring->head = head;
1029 ret = 1;
1030 put_aio_ring_event(evp, KM_USER1);
1031 }
1032 spin_unlock(&info->ring_lock);
1033
1034out:
1035 kunmap_atomic(ring, KM_USER0);
1036 dprintk("leaving aio_read_evt: %d h%lu t%lu\n", ret,
1037 (unsigned long)ring->head, (unsigned long)ring->tail);
1038 return ret;
1039}
1040
1041struct aio_timeout {
1042 struct timer_list timer;
1043 int timed_out;
1044 struct task_struct *p;
1045};
1046
1047static void timeout_func(unsigned long data)
1048{
1049 struct aio_timeout *to = (struct aio_timeout *)data;
1050
1051 to->timed_out = 1;
1052 wake_up_process(to->p);
1053}
1054
1055static inline void init_timeout(struct aio_timeout *to)
1056{
1057 setup_timer_on_stack(&to->timer, timeout_func, (unsigned long) to);
1058 to->timed_out = 0;
1059 to->p = current;
1060}
1061
1062static inline void set_timeout(long start_jiffies, struct aio_timeout *to,
1063 const struct timespec *ts)
1064{
1065 to->timer.expires = start_jiffies + timespec_to_jiffies(ts);
1066 if (time_after(to->timer.expires, jiffies))
1067 add_timer(&to->timer);
1068 else
1069 to->timed_out = 1;
1070}
1071
1072static inline void clear_timeout(struct aio_timeout *to)
1073{
1074 del_singleshot_timer_sync(&to->timer);
1075}
1076
1077static int read_events(struct kioctx *ctx,
1078 long min_nr, long nr,
1079 struct io_event __user *event,
1080 struct timespec __user *timeout)
1081{
1082 long start_jiffies = jiffies;
1083 struct task_struct *tsk = current;
1084 DECLARE_WAITQUEUE(wait, tsk);
1085 int ret;
1086 int i = 0;
1087 struct io_event ent;
1088 struct aio_timeout to;
1089 int retry = 0;
1090
1091 /* needed to zero any padding within an entry (there shouldn't be
1092 * any, but C is fun!
1093 */
1094 memset(&ent, 0, sizeof(ent));
1095retry:
1096 ret = 0;
1097 while (likely(i < nr)) {
1098 ret = aio_read_evt(ctx, &ent);
1099 if (unlikely(ret <= 0))
1100 break;
1101
1102 dprintk("read event: %Lx %Lx %Lx %Lx\n",
1103 ent.data, ent.obj, ent.res, ent.res2);
1104
1105 /* Could we split the check in two? */
1106 ret = -EFAULT;
1107 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
1108 dprintk("aio: lost an event due to EFAULT.\n");
1109 break;
1110 }
1111 ret = 0;
1112
1113 /* Good, event copied to userland, update counts. */
1114 event ++;
1115 i ++;
1116 }
1117
1118 if (min_nr <= i)
1119 return i;
1120 if (ret)
1121 return ret;
1122
1123 /* End fast path */
1124
1125 /* racey check, but it gets redone */
1126 if (!retry && unlikely(!list_empty(&ctx->run_list))) {
1127 retry = 1;
1128 aio_run_all_iocbs(ctx);
1129 goto retry;
1130 }
1131
1132 init_timeout(&to);
1133 if (timeout) {
1134 struct timespec ts;
1135 ret = -EFAULT;
1136 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
1137 goto out;
1138
1139 set_timeout(start_jiffies, &to, &ts);
1140 }
1141
1142 while (likely(i < nr)) {
1143 add_wait_queue_exclusive(&ctx->wait, &wait);
1144 do {
1145 set_task_state(tsk, TASK_INTERRUPTIBLE);
1146 ret = aio_read_evt(ctx, &ent);
1147 if (ret)
1148 break;
1149 if (min_nr <= i)
1150 break;
1151 if (unlikely(ctx->dead)) {
1152 ret = -EINVAL;
1153 break;
1154 }
1155 if (to.timed_out) /* Only check after read evt */
1156 break;
1157 /* Try to only show up in io wait if there are ops
1158 * in flight */
1159 if (ctx->reqs_active)
1160 io_schedule();
1161 else
1162 schedule();
1163 if (signal_pending(tsk)) {
1164 ret = -EINTR;
1165 break;
1166 }
1167 /*ret = aio_read_evt(ctx, &ent);*/
1168 } while (1) ;
1169
1170 set_task_state(tsk, TASK_RUNNING);
1171 remove_wait_queue(&ctx->wait, &wait);
1172
1173 if (unlikely(ret <= 0))
1174 break;
1175
1176 ret = -EFAULT;
1177 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
1178 dprintk("aio: lost an event due to EFAULT.\n");
1179 break;
1180 }
1181
1182 /* Good, event copied to userland, update counts. */
1183 event ++;
1184 i ++;
1185 }
1186
1187 if (timeout)
1188 clear_timeout(&to);
1189out:
1190 destroy_timer_on_stack(&to.timer);
1191 return i ? i : ret;
1192}
1193
1194/* Take an ioctx and remove it from the list of ioctx's. Protects
1195 * against races with itself via ->dead.
1196 */
1197static void io_destroy(struct kioctx *ioctx)
1198{
1199 struct mm_struct *mm = current->mm;
1200 int was_dead;
1201
1202 /* delete the entry from the list is someone else hasn't already */
1203 spin_lock(&mm->ioctx_lock);
1204 was_dead = ioctx->dead;
1205 ioctx->dead = 1;
1206 hlist_del_rcu(&ioctx->list);
1207 spin_unlock(&mm->ioctx_lock);
1208
1209 dprintk("aio_release(%p)\n", ioctx);
1210 if (likely(!was_dead))
1211 put_ioctx(ioctx); /* twice for the list */
1212
1213 aio_cancel_all(ioctx);
1214 wait_for_all_aios(ioctx);
1215
1216 /*
1217 * Wake up any waiters. The setting of ctx->dead must be seen
1218 * by other CPUs at this point. Right now, we rely on the
1219 * locking done by the above calls to ensure this consistency.
1220 */
1221 wake_up_all(&ioctx->wait);
1222 put_ioctx(ioctx); /* once for the lookup */
1223}
1224
1225/* sys_io_setup:
1226 * Create an aio_context capable of receiving at least nr_events.
1227 * ctxp must not point to an aio_context that already exists, and
1228 * must be initialized to 0 prior to the call. On successful
1229 * creation of the aio_context, *ctxp is filled in with the resulting
1230 * handle. May fail with -EINVAL if *ctxp is not initialized,
1231 * if the specified nr_events exceeds internal limits. May fail
1232 * with -EAGAIN if the specified nr_events exceeds the user's limit
1233 * of available events. May fail with -ENOMEM if insufficient kernel
1234 * resources are available. May fail with -EFAULT if an invalid
1235 * pointer is passed for ctxp. Will fail with -ENOSYS if not
1236 * implemented.
1237 */
1238SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1239{
1240 struct kioctx *ioctx = NULL;
1241 unsigned long ctx;
1242 long ret;
1243
1244 ret = get_user(ctx, ctxp);
1245 if (unlikely(ret))
1246 goto out;
1247
1248 ret = -EINVAL;
1249 if (unlikely(ctx || nr_events == 0)) {
1250 pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
1251 ctx, nr_events);
1252 goto out;
1253 }
1254
1255 ioctx = ioctx_alloc(nr_events);
1256 ret = PTR_ERR(ioctx);
1257 if (!IS_ERR(ioctx)) {
1258 ret = put_user(ioctx->user_id, ctxp);
1259 if (!ret)
1260 return 0;
1261
1262 get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */
1263 io_destroy(ioctx);
1264 }
1265
1266out:
1267 return ret;
1268}
1269
1270/* sys_io_destroy:
1271 * Destroy the aio_context specified. May cancel any outstanding
1272 * AIOs and block on completion. Will fail with -ENOSYS if not
1273 * implemented. May fail with -EINVAL if the context pointed to
1274 * is invalid.
1275 */
1276SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1277{
1278 struct kioctx *ioctx = lookup_ioctx(ctx);
1279 if (likely(NULL != ioctx)) {
1280 io_destroy(ioctx);
1281 return 0;
1282 }
1283 pr_debug("EINVAL: io_destroy: invalid context id\n");
1284 return -EINVAL;
1285}
1286
1287static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret)
1288{
1289 struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg];
1290
1291 BUG_ON(ret <= 0);
1292
1293 while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) {
1294 ssize_t this = min((ssize_t)iov->iov_len, ret);
1295 iov->iov_base += this;
1296 iov->iov_len -= this;
1297 iocb->ki_left -= this;
1298 ret -= this;
1299 if (iov->iov_len == 0) {
1300 iocb->ki_cur_seg++;
1301 iov++;
1302 }
1303 }
1304
1305 /* the caller should not have done more io than what fit in
1306 * the remaining iovecs */
1307 BUG_ON(ret > 0 && iocb->ki_left == 0);
1308}
1309
1310static ssize_t aio_rw_vect_retry(struct kiocb *iocb)
1311{
1312 struct file *file = iocb->ki_filp;
1313 struct address_space *mapping = file->f_mapping;
1314 struct inode *inode = mapping->host;
1315 ssize_t (*rw_op)(struct kiocb *, const struct iovec *,
1316 unsigned long, loff_t);
1317 ssize_t ret = 0;
1318 unsigned short opcode;
1319
1320 if ((iocb->ki_opcode == IOCB_CMD_PREADV) ||
1321 (iocb->ki_opcode == IOCB_CMD_PREAD)) {
1322 rw_op = file->f_op->aio_read;
1323 opcode = IOCB_CMD_PREADV;
1324 } else {
1325 rw_op = file->f_op->aio_write;
1326 opcode = IOCB_CMD_PWRITEV;
1327 }
1328
1329 /* This matches the pread()/pwrite() logic */
1330 if (iocb->ki_pos < 0)
1331 return -EINVAL;
1332
1333 do {
1334 ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg],
1335 iocb->ki_nr_segs - iocb->ki_cur_seg,
1336 iocb->ki_pos);
1337 if (ret > 0)
1338 aio_advance_iovec(iocb, ret);
1339
1340 /* retry all partial writes. retry partial reads as long as its a
1341 * regular file. */
1342 } while (ret > 0 && iocb->ki_left > 0 &&
1343 (opcode == IOCB_CMD_PWRITEV ||
1344 (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))));
1345
1346 /* This means we must have transferred all that we could */
1347 /* No need to retry anymore */
1348 if ((ret == 0) || (iocb->ki_left == 0))
1349 ret = iocb->ki_nbytes - iocb->ki_left;
1350
1351 /* If we managed to write some out we return that, rather than
1352 * the eventual error. */
1353 if (opcode == IOCB_CMD_PWRITEV
1354 && ret < 0 && ret != -EIOCBQUEUED && ret != -EIOCBRETRY
1355 && iocb->ki_nbytes - iocb->ki_left)
1356 ret = iocb->ki_nbytes - iocb->ki_left;
1357
1358 return ret;
1359}
1360
1361static ssize_t aio_fdsync(struct kiocb *iocb)
1362{
1363 struct file *file = iocb->ki_filp;
1364 ssize_t ret = -EINVAL;
1365
1366 if (file->f_op->aio_fsync)
1367 ret = file->f_op->aio_fsync(iocb, 1);
1368 return ret;
1369}
1370
1371static ssize_t aio_fsync(struct kiocb *iocb)
1372{
1373 struct file *file = iocb->ki_filp;
1374 ssize_t ret = -EINVAL;
1375
1376 if (file->f_op->aio_fsync)
1377 ret = file->f_op->aio_fsync(iocb, 0);
1378 return ret;
1379}
1380
1381static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb, bool compat)
1382{
1383 ssize_t ret;
1384
1385#ifdef CONFIG_COMPAT
1386 if (compat)
1387 ret = compat_rw_copy_check_uvector(type,
1388 (struct compat_iovec __user *)kiocb->ki_buf,
1389 kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
1390 &kiocb->ki_iovec);
1391 else
1392#endif
1393 ret = rw_copy_check_uvector(type,
1394 (struct iovec __user *)kiocb->ki_buf,
1395 kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
1396 &kiocb->ki_iovec);
1397 if (ret < 0)
1398 goto out;
1399
1400 kiocb->ki_nr_segs = kiocb->ki_nbytes;
1401 kiocb->ki_cur_seg = 0;
1402 /* ki_nbytes/left now reflect bytes instead of segs */
1403 kiocb->ki_nbytes = ret;
1404 kiocb->ki_left = ret;
1405
1406 ret = 0;
1407out:
1408 return ret;
1409}
1410
1411static ssize_t aio_setup_single_vector(struct kiocb *kiocb)
1412{
1413 kiocb->ki_iovec = &kiocb->ki_inline_vec;
1414 kiocb->ki_iovec->iov_base = kiocb->ki_buf;
1415 kiocb->ki_iovec->iov_len = kiocb->ki_left;
1416 kiocb->ki_nr_segs = 1;
1417 kiocb->ki_cur_seg = 0;
1418 return 0;
1419}
1420
1421/*
1422 * aio_setup_iocb:
1423 * Performs the initial checks and aio retry method
1424 * setup for the kiocb at the time of io submission.
1425 */
1426static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
1427{
1428 struct file *file = kiocb->ki_filp;
1429 ssize_t ret = 0;
1430
1431 switch (kiocb->ki_opcode) {
1432 case IOCB_CMD_PREAD:
1433 ret = -EBADF;
1434 if (unlikely(!(file->f_mode & FMODE_READ)))
1435 break;
1436 ret = -EFAULT;
1437 if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf,
1438 kiocb->ki_left)))
1439 break;
1440 ret = security_file_permission(file, MAY_READ);
1441 if (unlikely(ret))
1442 break;
1443 ret = aio_setup_single_vector(kiocb);
1444 if (ret)
1445 break;
1446 ret = -EINVAL;
1447 if (file->f_op->aio_read)
1448 kiocb->ki_retry = aio_rw_vect_retry;
1449 break;
1450 case IOCB_CMD_PWRITE:
1451 ret = -EBADF;
1452 if (unlikely(!(file->f_mode & FMODE_WRITE)))
1453 break;
1454 ret = -EFAULT;
1455 if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf,
1456 kiocb->ki_left)))
1457 break;
1458 ret = security_file_permission(file, MAY_WRITE);
1459 if (unlikely(ret))
1460 break;
1461 ret = aio_setup_single_vector(kiocb);
1462 if (ret)
1463 break;
1464 ret = -EINVAL;
1465 if (file->f_op->aio_write)
1466 kiocb->ki_retry = aio_rw_vect_retry;
1467 break;
1468 case IOCB_CMD_PREADV:
1469 ret = -EBADF;
1470 if (unlikely(!(file->f_mode & FMODE_READ)))
1471 break;
1472 ret = security_file_permission(file, MAY_READ);
1473 if (unlikely(ret))
1474 break;
1475 ret = aio_setup_vectored_rw(READ, kiocb, compat);
1476 if (ret)
1477 break;
1478 ret = -EINVAL;
1479 if (file->f_op->aio_read)
1480 kiocb->ki_retry = aio_rw_vect_retry;
1481 break;
1482 case IOCB_CMD_PWRITEV:
1483 ret = -EBADF;
1484 if (unlikely(!(file->f_mode & FMODE_WRITE)))
1485 break;
1486 ret = security_file_permission(file, MAY_WRITE);
1487 if (unlikely(ret))
1488 break;
1489 ret = aio_setup_vectored_rw(WRITE, kiocb, compat);
1490 if (ret)
1491 break;
1492 ret = -EINVAL;
1493 if (file->f_op->aio_write)
1494 kiocb->ki_retry = aio_rw_vect_retry;
1495 break;
1496 case IOCB_CMD_FDSYNC:
1497 ret = -EINVAL;
1498 if (file->f_op->aio_fsync)
1499 kiocb->ki_retry = aio_fdsync;
1500 break;
1501 case IOCB_CMD_FSYNC:
1502 ret = -EINVAL;
1503 if (file->f_op->aio_fsync)
1504 kiocb->ki_retry = aio_fsync;
1505 break;
1506 default:
1507 dprintk("EINVAL: io_submit: no operation provided\n");
1508 ret = -EINVAL;
1509 }
1510
1511 if (!kiocb->ki_retry)
1512 return ret;
1513
1514 return 0;
1515}
1516
1517static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1518 struct iocb *iocb, bool compat)
1519{
1520 struct kiocb *req;
1521 struct file *file;
1522 ssize_t ret;
1523
1524 /* enforce forwards compatibility on users */
1525 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
1526 pr_debug("EINVAL: io_submit: reserve field set\n");
1527 return -EINVAL;
1528 }
1529
1530 /* prevent overflows */
1531 if (unlikely(
1532 (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
1533 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
1534 ((ssize_t)iocb->aio_nbytes < 0)
1535 )) {
1536 pr_debug("EINVAL: io_submit: overflow check\n");
1537 return -EINVAL;
1538 }
1539
1540 file = fget(iocb->aio_fildes);
1541 if (unlikely(!file))
1542 return -EBADF;
1543
1544 req = aio_get_req(ctx); /* returns with 2 references to req */
1545 if (unlikely(!req)) {
1546 fput(file);
1547 return -EAGAIN;
1548 }
1549 req->ki_filp = file;
1550 if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1551 /*
1552 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1553 * instance of the file* now. The file descriptor must be
1554 * an eventfd() fd, and will be signaled for each completed
1555 * event using the eventfd_signal() function.
1556 */
1557 req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
1558 if (IS_ERR(req->ki_eventfd)) {
1559 ret = PTR_ERR(req->ki_eventfd);
1560 req->ki_eventfd = NULL;
1561 goto out_put_req;
1562 }
1563 }
1564
1565 ret = put_user(req->ki_key, &user_iocb->aio_key);
1566 if (unlikely(ret)) {
1567 dprintk("EFAULT: aio_key\n");
1568 goto out_put_req;
1569 }
1570
1571 req->ki_obj.user = user_iocb;
1572 req->ki_user_data = iocb->aio_data;
1573 req->ki_pos = iocb->aio_offset;
1574
1575 req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf;
1576 req->ki_left = req->ki_nbytes = iocb->aio_nbytes;
1577 req->ki_opcode = iocb->aio_lio_opcode;
1578
1579 ret = aio_setup_iocb(req, compat);
1580
1581 if (ret)
1582 goto out_put_req;
1583
1584 spin_lock_irq(&ctx->ctx_lock);
1585 /*
1586 * We could have raced with io_destroy() and are currently holding a
1587 * reference to ctx which should be destroyed. We cannot submit IO
1588 * since ctx gets freed as soon as io_submit() puts its reference. The
1589 * check here is reliable: io_destroy() sets ctx->dead before waiting
1590 * for outstanding IO and the barrier between these two is realized by
1591 * unlock of mm->ioctx_lock and lock of ctx->ctx_lock. Analogously we
1592 * increment ctx->reqs_active before checking for ctx->dead and the
1593 * barrier is realized by unlock and lock of ctx->ctx_lock. Thus if we
1594 * don't see ctx->dead set here, io_destroy() waits for our IO to
1595 * finish.
1596 */
1597 if (ctx->dead) {
1598 spin_unlock_irq(&ctx->ctx_lock);
1599 ret = -EINVAL;
1600 goto out_put_req;
1601 }
1602 aio_run_iocb(req);
1603 if (!list_empty(&ctx->run_list)) {
1604 /* drain the run list */
1605 while (__aio_run_iocbs(ctx))
1606 ;
1607 }
1608 spin_unlock_irq(&ctx->ctx_lock);
1609
1610 aio_put_req(req); /* drop extra ref to req */
1611 return 0;
1612
1613out_put_req:
1614 aio_put_req(req); /* drop extra ref to req */
1615 aio_put_req(req); /* drop i/o ref to req */
1616 return ret;
1617}
1618
1619long do_io_submit(aio_context_t ctx_id, long nr,
1620 struct iocb __user *__user *iocbpp, bool compat)
1621{
1622 struct kioctx *ctx;
1623 long ret = 0;
1624 int i;
1625 struct blk_plug plug;
1626
1627 if (unlikely(nr < 0))
1628 return -EINVAL;
1629
1630 if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
1631 nr = LONG_MAX/sizeof(*iocbpp);
1632
1633 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1634 return -EFAULT;
1635
1636 ctx = lookup_ioctx(ctx_id);
1637 if (unlikely(!ctx)) {
1638 pr_debug("EINVAL: io_submit: invalid context id\n");
1639 return -EINVAL;
1640 }
1641
1642 blk_start_plug(&plug);
1643
1644 /*
1645 * AKPM: should this return a partial result if some of the IOs were
1646 * successfully submitted?
1647 */
1648 for (i=0; i<nr; i++) {
1649 struct iocb __user *user_iocb;
1650 struct iocb tmp;
1651
1652 if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1653 ret = -EFAULT;
1654 break;
1655 }
1656
1657 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1658 ret = -EFAULT;
1659 break;
1660 }
1661
1662 ret = io_submit_one(ctx, user_iocb, &tmp, compat);
1663 if (ret)
1664 break;
1665 }
1666 blk_finish_plug(&plug);
1667
1668 put_ioctx(ctx);
1669 return i ? i : ret;
1670}
1671
1672/* sys_io_submit:
1673 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1674 * the number of iocbs queued. May return -EINVAL if the aio_context
1675 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1676 * *iocbpp[0] is not properly initialized, if the operation specified
1677 * is invalid for the file descriptor in the iocb. May fail with
1678 * -EFAULT if any of the data structures point to invalid data. May
1679 * fail with -EBADF if the file descriptor specified in the first
1680 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1681 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1682 * fail with -ENOSYS if not implemented.
1683 */
1684SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
1685 struct iocb __user * __user *, iocbpp)
1686{
1687 return do_io_submit(ctx_id, nr, iocbpp, 0);
1688}
1689
1690/* lookup_kiocb
1691 * Finds a given iocb for cancellation.
1692 */
1693static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
1694 u32 key)
1695{
1696 struct list_head *pos;
1697
1698 assert_spin_locked(&ctx->ctx_lock);
1699
1700 /* TODO: use a hash or array, this sucks. */
1701 list_for_each(pos, &ctx->active_reqs) {
1702 struct kiocb *kiocb = list_kiocb(pos);
1703 if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key)
1704 return kiocb;
1705 }
1706 return NULL;
1707}
1708
1709/* sys_io_cancel:
1710 * Attempts to cancel an iocb previously passed to io_submit. If
1711 * the operation is successfully cancelled, the resulting event is
1712 * copied into the memory pointed to by result without being placed
1713 * into the completion queue and 0 is returned. May fail with
1714 * -EFAULT if any of the data structures pointed to are invalid.
1715 * May fail with -EINVAL if aio_context specified by ctx_id is
1716 * invalid. May fail with -EAGAIN if the iocb specified was not
1717 * cancelled. Will fail with -ENOSYS if not implemented.
1718 */
1719SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
1720 struct io_event __user *, result)
1721{
1722 int (*cancel)(struct kiocb *iocb, struct io_event *res);
1723 struct kioctx *ctx;
1724 struct kiocb *kiocb;
1725 u32 key;
1726 int ret;
1727
1728 ret = get_user(key, &iocb->aio_key);
1729 if (unlikely(ret))
1730 return -EFAULT;
1731
1732 ctx = lookup_ioctx(ctx_id);
1733 if (unlikely(!ctx))
1734 return -EINVAL;
1735
1736 spin_lock_irq(&ctx->ctx_lock);
1737 ret = -EAGAIN;
1738 kiocb = lookup_kiocb(ctx, iocb, key);
1739 if (kiocb && kiocb->ki_cancel) {
1740 cancel = kiocb->ki_cancel;
1741 kiocb->ki_users ++;
1742 kiocbSetCancelled(kiocb);
1743 } else
1744 cancel = NULL;
1745 spin_unlock_irq(&ctx->ctx_lock);
1746
1747 if (NULL != cancel) {
1748 struct io_event tmp;
1749 pr_debug("calling cancel\n");
1750 memset(&tmp, 0, sizeof(tmp));
1751 tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user;
1752 tmp.data = kiocb->ki_user_data;
1753 ret = cancel(kiocb, &tmp);
1754 if (!ret) {
1755 /* Cancellation succeeded -- copy the result
1756 * into the user's buffer.
1757 */
1758 if (copy_to_user(result, &tmp, sizeof(tmp)))
1759 ret = -EFAULT;
1760 }
1761 } else
1762 ret = -EINVAL;
1763
1764 put_ioctx(ctx);
1765
1766 return ret;
1767}
1768
1769/* io_getevents:
1770 * Attempts to read at least min_nr events and up to nr events from
1771 * the completion queue for the aio_context specified by ctx_id. If
1772 * it succeeds, the number of read events is returned. May fail with
1773 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
1774 * out of range, if timeout is out of range. May fail with -EFAULT
1775 * if any of the memory specified is invalid. May return 0 or
1776 * < min_nr if the timeout specified by timeout has elapsed
1777 * before sufficient events are available, where timeout == NULL
1778 * specifies an infinite timeout. Note that the timeout pointed to by
1779 * timeout is relative and will be updated if not NULL and the
1780 * operation blocks. Will fail with -ENOSYS if not implemented.
1781 */
1782SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
1783 long, min_nr,
1784 long, nr,
1785 struct io_event __user *, events,
1786 struct timespec __user *, timeout)
1787{
1788 struct kioctx *ioctx = lookup_ioctx(ctx_id);
1789 long ret = -EINVAL;
1790
1791 if (likely(ioctx)) {
1792 if (likely(min_nr <= nr && min_nr >= 0))
1793 ret = read_events(ioctx, min_nr, nr, events, timeout);
1794 put_ioctx(ioctx);
1795 }
1796
1797 asmlinkage_protect(5, ret, ctx_id, min_nr, nr, events, timeout);
1798 return ret;
1799}
1/*
2 * An async IO implementation for Linux
3 * Written by Benjamin LaHaise <bcrl@kvack.org>
4 *
5 * Implements an efficient asynchronous io interface.
6 *
7 * Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved.
8 *
9 * See ../COPYING for licensing terms.
10 */
11#define pr_fmt(fmt) "%s: " fmt, __func__
12
13#include <linux/kernel.h>
14#include <linux/init.h>
15#include <linux/errno.h>
16#include <linux/time.h>
17#include <linux/aio_abi.h>
18#include <linux/export.h>
19#include <linux/syscalls.h>
20#include <linux/backing-dev.h>
21#include <linux/uio.h>
22
23#include <linux/sched.h>
24#include <linux/fs.h>
25#include <linux/file.h>
26#include <linux/mm.h>
27#include <linux/mman.h>
28#include <linux/mmu_context.h>
29#include <linux/percpu.h>
30#include <linux/slab.h>
31#include <linux/timer.h>
32#include <linux/aio.h>
33#include <linux/highmem.h>
34#include <linux/workqueue.h>
35#include <linux/security.h>
36#include <linux/eventfd.h>
37#include <linux/blkdev.h>
38#include <linux/compat.h>
39#include <linux/migrate.h>
40#include <linux/ramfs.h>
41#include <linux/percpu-refcount.h>
42#include <linux/mount.h>
43
44#include <asm/kmap_types.h>
45#include <asm/uaccess.h>
46
47#include "internal.h"
48
49#define AIO_RING_MAGIC 0xa10a10a1
50#define AIO_RING_COMPAT_FEATURES 1
51#define AIO_RING_INCOMPAT_FEATURES 0
52struct aio_ring {
53 unsigned id; /* kernel internal index number */
54 unsigned nr; /* number of io_events */
55 unsigned head; /* Written to by userland or under ring_lock
56 * mutex by aio_read_events_ring(). */
57 unsigned tail;
58
59 unsigned magic;
60 unsigned compat_features;
61 unsigned incompat_features;
62 unsigned header_length; /* size of aio_ring */
63
64
65 struct io_event io_events[0];
66}; /* 128 bytes + ring size */
67
68#define AIO_RING_PAGES 8
69
70struct kioctx_table {
71 struct rcu_head rcu;
72 unsigned nr;
73 struct kioctx *table[];
74};
75
76struct kioctx_cpu {
77 unsigned reqs_available;
78};
79
80struct kioctx {
81 struct percpu_ref users;
82 atomic_t dead;
83
84 struct percpu_ref reqs;
85
86 unsigned long user_id;
87
88 struct __percpu kioctx_cpu *cpu;
89
90 /*
91 * For percpu reqs_available, number of slots we move to/from global
92 * counter at a time:
93 */
94 unsigned req_batch;
95 /*
96 * This is what userspace passed to io_setup(), it's not used for
97 * anything but counting against the global max_reqs quota.
98 *
99 * The real limit is nr_events - 1, which will be larger (see
100 * aio_setup_ring())
101 */
102 unsigned max_reqs;
103
104 /* Size of ringbuffer, in units of struct io_event */
105 unsigned nr_events;
106
107 unsigned long mmap_base;
108 unsigned long mmap_size;
109
110 struct page **ring_pages;
111 long nr_pages;
112
113 struct work_struct free_work;
114
115 /*
116 * signals when all in-flight requests are done
117 */
118 struct completion *requests_done;
119
120 struct {
121 /*
122 * This counts the number of available slots in the ringbuffer,
123 * so we avoid overflowing it: it's decremented (if positive)
124 * when allocating a kiocb and incremented when the resulting
125 * io_event is pulled off the ringbuffer.
126 *
127 * We batch accesses to it with a percpu version.
128 */
129 atomic_t reqs_available;
130 } ____cacheline_aligned_in_smp;
131
132 struct {
133 spinlock_t ctx_lock;
134 struct list_head active_reqs; /* used for cancellation */
135 } ____cacheline_aligned_in_smp;
136
137 struct {
138 struct mutex ring_lock;
139 wait_queue_head_t wait;
140 } ____cacheline_aligned_in_smp;
141
142 struct {
143 unsigned tail;
144 spinlock_t completion_lock;
145 } ____cacheline_aligned_in_smp;
146
147 struct page *internal_pages[AIO_RING_PAGES];
148 struct file *aio_ring_file;
149
150 unsigned id;
151};
152
153/*------ sysctl variables----*/
154static DEFINE_SPINLOCK(aio_nr_lock);
155unsigned long aio_nr; /* current system wide number of aio requests */
156unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
157/*----end sysctl variables---*/
158
159static struct kmem_cache *kiocb_cachep;
160static struct kmem_cache *kioctx_cachep;
161
162static struct vfsmount *aio_mnt;
163
164static const struct file_operations aio_ring_fops;
165static const struct address_space_operations aio_ctx_aops;
166
167static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
168{
169 struct qstr this = QSTR_INIT("[aio]", 5);
170 struct file *file;
171 struct path path;
172 struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
173 if (IS_ERR(inode))
174 return ERR_CAST(inode);
175
176 inode->i_mapping->a_ops = &aio_ctx_aops;
177 inode->i_mapping->private_data = ctx;
178 inode->i_size = PAGE_SIZE * nr_pages;
179
180 path.dentry = d_alloc_pseudo(aio_mnt->mnt_sb, &this);
181 if (!path.dentry) {
182 iput(inode);
183 return ERR_PTR(-ENOMEM);
184 }
185 path.mnt = mntget(aio_mnt);
186
187 d_instantiate(path.dentry, inode);
188 file = alloc_file(&path, FMODE_READ | FMODE_WRITE, &aio_ring_fops);
189 if (IS_ERR(file)) {
190 path_put(&path);
191 return file;
192 }
193
194 file->f_flags = O_RDWR;
195 file->private_data = ctx;
196 return file;
197}
198
199static struct dentry *aio_mount(struct file_system_type *fs_type,
200 int flags, const char *dev_name, void *data)
201{
202 static const struct dentry_operations ops = {
203 .d_dname = simple_dname,
204 };
205 return mount_pseudo(fs_type, "aio:", NULL, &ops, 0xa10a10a1);
206}
207
208/* aio_setup
209 * Creates the slab caches used by the aio routines, panic on
210 * failure as this is done early during the boot sequence.
211 */
212static int __init aio_setup(void)
213{
214 static struct file_system_type aio_fs = {
215 .name = "aio",
216 .mount = aio_mount,
217 .kill_sb = kill_anon_super,
218 };
219 aio_mnt = kern_mount(&aio_fs);
220 if (IS_ERR(aio_mnt))
221 panic("Failed to create aio fs mount.");
222
223 kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
224 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
225
226 pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
227
228 return 0;
229}
230__initcall(aio_setup);
231
232static void put_aio_ring_file(struct kioctx *ctx)
233{
234 struct file *aio_ring_file = ctx->aio_ring_file;
235 if (aio_ring_file) {
236 truncate_setsize(aio_ring_file->f_inode, 0);
237
238 /* Prevent further access to the kioctx from migratepages */
239 spin_lock(&aio_ring_file->f_inode->i_mapping->private_lock);
240 aio_ring_file->f_inode->i_mapping->private_data = NULL;
241 ctx->aio_ring_file = NULL;
242 spin_unlock(&aio_ring_file->f_inode->i_mapping->private_lock);
243
244 fput(aio_ring_file);
245 }
246}
247
248static void aio_free_ring(struct kioctx *ctx)
249{
250 int i;
251
252 /* Disconnect the kiotx from the ring file. This prevents future
253 * accesses to the kioctx from page migration.
254 */
255 put_aio_ring_file(ctx);
256
257 for (i = 0; i < ctx->nr_pages; i++) {
258 struct page *page;
259 pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
260 page_count(ctx->ring_pages[i]));
261 page = ctx->ring_pages[i];
262 if (!page)
263 continue;
264 ctx->ring_pages[i] = NULL;
265 put_page(page);
266 }
267
268 if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
269 kfree(ctx->ring_pages);
270 ctx->ring_pages = NULL;
271 }
272}
273
274static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
275{
276 vma->vm_ops = &generic_file_vm_ops;
277 return 0;
278}
279
280static const struct file_operations aio_ring_fops = {
281 .mmap = aio_ring_mmap,
282};
283
284static int aio_set_page_dirty(struct page *page)
285{
286 return 0;
287}
288
289#if IS_ENABLED(CONFIG_MIGRATION)
290static int aio_migratepage(struct address_space *mapping, struct page *new,
291 struct page *old, enum migrate_mode mode)
292{
293 struct kioctx *ctx;
294 unsigned long flags;
295 pgoff_t idx;
296 int rc;
297
298 rc = 0;
299
300 /* mapping->private_lock here protects against the kioctx teardown. */
301 spin_lock(&mapping->private_lock);
302 ctx = mapping->private_data;
303 if (!ctx) {
304 rc = -EINVAL;
305 goto out;
306 }
307
308 /* The ring_lock mutex. The prevents aio_read_events() from writing
309 * to the ring's head, and prevents page migration from mucking in
310 * a partially initialized kiotx.
311 */
312 if (!mutex_trylock(&ctx->ring_lock)) {
313 rc = -EAGAIN;
314 goto out;
315 }
316
317 idx = old->index;
318 if (idx < (pgoff_t)ctx->nr_pages) {
319 /* Make sure the old page hasn't already been changed */
320 if (ctx->ring_pages[idx] != old)
321 rc = -EAGAIN;
322 } else
323 rc = -EINVAL;
324
325 if (rc != 0)
326 goto out_unlock;
327
328 /* Writeback must be complete */
329 BUG_ON(PageWriteback(old));
330 get_page(new);
331
332 rc = migrate_page_move_mapping(mapping, new, old, NULL, mode, 1);
333 if (rc != MIGRATEPAGE_SUCCESS) {
334 put_page(new);
335 goto out_unlock;
336 }
337
338 /* Take completion_lock to prevent other writes to the ring buffer
339 * while the old page is copied to the new. This prevents new
340 * events from being lost.
341 */
342 spin_lock_irqsave(&ctx->completion_lock, flags);
343 migrate_page_copy(new, old);
344 BUG_ON(ctx->ring_pages[idx] != old);
345 ctx->ring_pages[idx] = new;
346 spin_unlock_irqrestore(&ctx->completion_lock, flags);
347
348 /* The old page is no longer accessible. */
349 put_page(old);
350
351out_unlock:
352 mutex_unlock(&ctx->ring_lock);
353out:
354 spin_unlock(&mapping->private_lock);
355 return rc;
356}
357#endif
358
359static const struct address_space_operations aio_ctx_aops = {
360 .set_page_dirty = aio_set_page_dirty,
361#if IS_ENABLED(CONFIG_MIGRATION)
362 .migratepage = aio_migratepage,
363#endif
364};
365
366static int aio_setup_ring(struct kioctx *ctx)
367{
368 struct aio_ring *ring;
369 unsigned nr_events = ctx->max_reqs;
370 struct mm_struct *mm = current->mm;
371 unsigned long size, unused;
372 int nr_pages;
373 int i;
374 struct file *file;
375
376 /* Compensate for the ring buffer's head/tail overlap entry */
377 nr_events += 2; /* 1 is required, 2 for good luck */
378
379 size = sizeof(struct aio_ring);
380 size += sizeof(struct io_event) * nr_events;
381
382 nr_pages = PFN_UP(size);
383 if (nr_pages < 0)
384 return -EINVAL;
385
386 file = aio_private_file(ctx, nr_pages);
387 if (IS_ERR(file)) {
388 ctx->aio_ring_file = NULL;
389 return -ENOMEM;
390 }
391
392 ctx->aio_ring_file = file;
393 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
394 / sizeof(struct io_event);
395
396 ctx->ring_pages = ctx->internal_pages;
397 if (nr_pages > AIO_RING_PAGES) {
398 ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
399 GFP_KERNEL);
400 if (!ctx->ring_pages) {
401 put_aio_ring_file(ctx);
402 return -ENOMEM;
403 }
404 }
405
406 for (i = 0; i < nr_pages; i++) {
407 struct page *page;
408 page = find_or_create_page(file->f_inode->i_mapping,
409 i, GFP_HIGHUSER | __GFP_ZERO);
410 if (!page)
411 break;
412 pr_debug("pid(%d) page[%d]->count=%d\n",
413 current->pid, i, page_count(page));
414 SetPageUptodate(page);
415 SetPageDirty(page);
416 unlock_page(page);
417
418 ctx->ring_pages[i] = page;
419 }
420 ctx->nr_pages = i;
421
422 if (unlikely(i != nr_pages)) {
423 aio_free_ring(ctx);
424 return -ENOMEM;
425 }
426
427 ctx->mmap_size = nr_pages * PAGE_SIZE;
428 pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
429
430 down_write(&mm->mmap_sem);
431 ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size,
432 PROT_READ | PROT_WRITE,
433 MAP_SHARED, 0, &unused);
434 up_write(&mm->mmap_sem);
435 if (IS_ERR((void *)ctx->mmap_base)) {
436 ctx->mmap_size = 0;
437 aio_free_ring(ctx);
438 return -ENOMEM;
439 }
440
441 pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
442
443 ctx->user_id = ctx->mmap_base;
444 ctx->nr_events = nr_events; /* trusted copy */
445
446 ring = kmap_atomic(ctx->ring_pages[0]);
447 ring->nr = nr_events; /* user copy */
448 ring->id = ~0U;
449 ring->head = ring->tail = 0;
450 ring->magic = AIO_RING_MAGIC;
451 ring->compat_features = AIO_RING_COMPAT_FEATURES;
452 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
453 ring->header_length = sizeof(struct aio_ring);
454 kunmap_atomic(ring);
455 flush_dcache_page(ctx->ring_pages[0]);
456
457 return 0;
458}
459
460#define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
461#define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
462#define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
463
464void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel)
465{
466 struct kioctx *ctx = req->ki_ctx;
467 unsigned long flags;
468
469 spin_lock_irqsave(&ctx->ctx_lock, flags);
470
471 if (!req->ki_list.next)
472 list_add(&req->ki_list, &ctx->active_reqs);
473
474 req->ki_cancel = cancel;
475
476 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
477}
478EXPORT_SYMBOL(kiocb_set_cancel_fn);
479
480static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb)
481{
482 kiocb_cancel_fn *old, *cancel;
483
484 /*
485 * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
486 * actually has a cancel function, hence the cmpxchg()
487 */
488
489 cancel = ACCESS_ONCE(kiocb->ki_cancel);
490 do {
491 if (!cancel || cancel == KIOCB_CANCELLED)
492 return -EINVAL;
493
494 old = cancel;
495 cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
496 } while (cancel != old);
497
498 return cancel(kiocb);
499}
500
501static void free_ioctx(struct work_struct *work)
502{
503 struct kioctx *ctx = container_of(work, struct kioctx, free_work);
504
505 pr_debug("freeing %p\n", ctx);
506
507 aio_free_ring(ctx);
508 free_percpu(ctx->cpu);
509 kmem_cache_free(kioctx_cachep, ctx);
510}
511
512static void free_ioctx_reqs(struct percpu_ref *ref)
513{
514 struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
515
516 /* At this point we know that there are no any in-flight requests */
517 if (ctx->requests_done)
518 complete(ctx->requests_done);
519
520 INIT_WORK(&ctx->free_work, free_ioctx);
521 schedule_work(&ctx->free_work);
522}
523
524/*
525 * When this function runs, the kioctx has been removed from the "hash table"
526 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
527 * now it's safe to cancel any that need to be.
528 */
529static void free_ioctx_users(struct percpu_ref *ref)
530{
531 struct kioctx *ctx = container_of(ref, struct kioctx, users);
532 struct kiocb *req;
533
534 spin_lock_irq(&ctx->ctx_lock);
535
536 while (!list_empty(&ctx->active_reqs)) {
537 req = list_first_entry(&ctx->active_reqs,
538 struct kiocb, ki_list);
539
540 list_del_init(&req->ki_list);
541 kiocb_cancel(ctx, req);
542 }
543
544 spin_unlock_irq(&ctx->ctx_lock);
545
546 percpu_ref_kill(&ctx->reqs);
547 percpu_ref_put(&ctx->reqs);
548}
549
550static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
551{
552 unsigned i, new_nr;
553 struct kioctx_table *table, *old;
554 struct aio_ring *ring;
555
556 spin_lock(&mm->ioctx_lock);
557 rcu_read_lock();
558 table = rcu_dereference(mm->ioctx_table);
559
560 while (1) {
561 if (table)
562 for (i = 0; i < table->nr; i++)
563 if (!table->table[i]) {
564 ctx->id = i;
565 table->table[i] = ctx;
566 rcu_read_unlock();
567 spin_unlock(&mm->ioctx_lock);
568
569 /* While kioctx setup is in progress,
570 * we are protected from page migration
571 * changes ring_pages by ->ring_lock.
572 */
573 ring = kmap_atomic(ctx->ring_pages[0]);
574 ring->id = ctx->id;
575 kunmap_atomic(ring);
576 return 0;
577 }
578
579 new_nr = (table ? table->nr : 1) * 4;
580
581 rcu_read_unlock();
582 spin_unlock(&mm->ioctx_lock);
583
584 table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) *
585 new_nr, GFP_KERNEL);
586 if (!table)
587 return -ENOMEM;
588
589 table->nr = new_nr;
590
591 spin_lock(&mm->ioctx_lock);
592 rcu_read_lock();
593 old = rcu_dereference(mm->ioctx_table);
594
595 if (!old) {
596 rcu_assign_pointer(mm->ioctx_table, table);
597 } else if (table->nr > old->nr) {
598 memcpy(table->table, old->table,
599 old->nr * sizeof(struct kioctx *));
600
601 rcu_assign_pointer(mm->ioctx_table, table);
602 kfree_rcu(old, rcu);
603 } else {
604 kfree(table);
605 table = old;
606 }
607 }
608}
609
610static void aio_nr_sub(unsigned nr)
611{
612 spin_lock(&aio_nr_lock);
613 if (WARN_ON(aio_nr - nr > aio_nr))
614 aio_nr = 0;
615 else
616 aio_nr -= nr;
617 spin_unlock(&aio_nr_lock);
618}
619
620/* ioctx_alloc
621 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
622 */
623static struct kioctx *ioctx_alloc(unsigned nr_events)
624{
625 struct mm_struct *mm = current->mm;
626 struct kioctx *ctx;
627 int err = -ENOMEM;
628
629 /*
630 * We keep track of the number of available ringbuffer slots, to prevent
631 * overflow (reqs_available), and we also use percpu counters for this.
632 *
633 * So since up to half the slots might be on other cpu's percpu counters
634 * and unavailable, double nr_events so userspace sees what they
635 * expected: additionally, we move req_batch slots to/from percpu
636 * counters at a time, so make sure that isn't 0:
637 */
638 nr_events = max(nr_events, num_possible_cpus() * 4);
639 nr_events *= 2;
640
641 /* Prevent overflows */
642 if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
643 (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
644 pr_debug("ENOMEM: nr_events too high\n");
645 return ERR_PTR(-EINVAL);
646 }
647
648 if (!nr_events || (unsigned long)nr_events > (aio_max_nr * 2UL))
649 return ERR_PTR(-EAGAIN);
650
651 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
652 if (!ctx)
653 return ERR_PTR(-ENOMEM);
654
655 ctx->max_reqs = nr_events;
656
657 spin_lock_init(&ctx->ctx_lock);
658 spin_lock_init(&ctx->completion_lock);
659 mutex_init(&ctx->ring_lock);
660 /* Protect against page migration throughout kiotx setup by keeping
661 * the ring_lock mutex held until setup is complete. */
662 mutex_lock(&ctx->ring_lock);
663 init_waitqueue_head(&ctx->wait);
664
665 INIT_LIST_HEAD(&ctx->active_reqs);
666
667 if (percpu_ref_init(&ctx->users, free_ioctx_users))
668 goto err;
669
670 if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs))
671 goto err;
672
673 ctx->cpu = alloc_percpu(struct kioctx_cpu);
674 if (!ctx->cpu)
675 goto err;
676
677 err = aio_setup_ring(ctx);
678 if (err < 0)
679 goto err;
680
681 atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
682 ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
683 if (ctx->req_batch < 1)
684 ctx->req_batch = 1;
685
686 /* limit the number of system wide aios */
687 spin_lock(&aio_nr_lock);
688 if (aio_nr + nr_events > (aio_max_nr * 2UL) ||
689 aio_nr + nr_events < aio_nr) {
690 spin_unlock(&aio_nr_lock);
691 err = -EAGAIN;
692 goto err_ctx;
693 }
694 aio_nr += ctx->max_reqs;
695 spin_unlock(&aio_nr_lock);
696
697 percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */
698 percpu_ref_get(&ctx->reqs); /* free_ioctx_users() will drop this */
699
700 err = ioctx_add_table(ctx, mm);
701 if (err)
702 goto err_cleanup;
703
704 /* Release the ring_lock mutex now that all setup is complete. */
705 mutex_unlock(&ctx->ring_lock);
706
707 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
708 ctx, ctx->user_id, mm, ctx->nr_events);
709 return ctx;
710
711err_cleanup:
712 aio_nr_sub(ctx->max_reqs);
713err_ctx:
714 aio_free_ring(ctx);
715err:
716 mutex_unlock(&ctx->ring_lock);
717 free_percpu(ctx->cpu);
718 free_percpu(ctx->reqs.pcpu_count);
719 free_percpu(ctx->users.pcpu_count);
720 kmem_cache_free(kioctx_cachep, ctx);
721 pr_debug("error allocating ioctx %d\n", err);
722 return ERR_PTR(err);
723}
724
725/* kill_ioctx
726 * Cancels all outstanding aio requests on an aio context. Used
727 * when the processes owning a context have all exited to encourage
728 * the rapid destruction of the kioctx.
729 */
730static void kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
731 struct completion *requests_done)
732{
733 if (!atomic_xchg(&ctx->dead, 1)) {
734 struct kioctx_table *table;
735
736 spin_lock(&mm->ioctx_lock);
737 rcu_read_lock();
738 table = rcu_dereference(mm->ioctx_table);
739
740 WARN_ON(ctx != table->table[ctx->id]);
741 table->table[ctx->id] = NULL;
742 rcu_read_unlock();
743 spin_unlock(&mm->ioctx_lock);
744
745 /* percpu_ref_kill() will do the necessary call_rcu() */
746 wake_up_all(&ctx->wait);
747
748 /*
749 * It'd be more correct to do this in free_ioctx(), after all
750 * the outstanding kiocbs have finished - but by then io_destroy
751 * has already returned, so io_setup() could potentially return
752 * -EAGAIN with no ioctxs actually in use (as far as userspace
753 * could tell).
754 */
755 aio_nr_sub(ctx->max_reqs);
756
757 if (ctx->mmap_size)
758 vm_munmap(ctx->mmap_base, ctx->mmap_size);
759
760 ctx->requests_done = requests_done;
761 percpu_ref_kill(&ctx->users);
762 } else {
763 if (requests_done)
764 complete(requests_done);
765 }
766}
767
768/* wait_on_sync_kiocb:
769 * Waits on the given sync kiocb to complete.
770 */
771ssize_t wait_on_sync_kiocb(struct kiocb *req)
772{
773 while (!req->ki_ctx) {
774 set_current_state(TASK_UNINTERRUPTIBLE);
775 if (req->ki_ctx)
776 break;
777 io_schedule();
778 }
779 __set_current_state(TASK_RUNNING);
780 return req->ki_user_data;
781}
782EXPORT_SYMBOL(wait_on_sync_kiocb);
783
784/*
785 * exit_aio: called when the last user of mm goes away. At this point, there is
786 * no way for any new requests to be submited or any of the io_* syscalls to be
787 * called on the context.
788 *
789 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
790 * them.
791 */
792void exit_aio(struct mm_struct *mm)
793{
794 struct kioctx_table *table;
795 struct kioctx *ctx;
796 unsigned i = 0;
797
798 while (1) {
799 rcu_read_lock();
800 table = rcu_dereference(mm->ioctx_table);
801
802 do {
803 if (!table || i >= table->nr) {
804 rcu_read_unlock();
805 rcu_assign_pointer(mm->ioctx_table, NULL);
806 if (table)
807 kfree(table);
808 return;
809 }
810
811 ctx = table->table[i++];
812 } while (!ctx);
813
814 rcu_read_unlock();
815
816 /*
817 * We don't need to bother with munmap() here -
818 * exit_mmap(mm) is coming and it'll unmap everything.
819 * Since aio_free_ring() uses non-zero ->mmap_size
820 * as indicator that it needs to unmap the area,
821 * just set it to 0; aio_free_ring() is the only
822 * place that uses ->mmap_size, so it's safe.
823 */
824 ctx->mmap_size = 0;
825
826 kill_ioctx(mm, ctx, NULL);
827 }
828}
829
830static void put_reqs_available(struct kioctx *ctx, unsigned nr)
831{
832 struct kioctx_cpu *kcpu;
833
834 preempt_disable();
835 kcpu = this_cpu_ptr(ctx->cpu);
836
837 kcpu->reqs_available += nr;
838 while (kcpu->reqs_available >= ctx->req_batch * 2) {
839 kcpu->reqs_available -= ctx->req_batch;
840 atomic_add(ctx->req_batch, &ctx->reqs_available);
841 }
842
843 preempt_enable();
844}
845
846static bool get_reqs_available(struct kioctx *ctx)
847{
848 struct kioctx_cpu *kcpu;
849 bool ret = false;
850
851 preempt_disable();
852 kcpu = this_cpu_ptr(ctx->cpu);
853
854 if (!kcpu->reqs_available) {
855 int old, avail = atomic_read(&ctx->reqs_available);
856
857 do {
858 if (avail < ctx->req_batch)
859 goto out;
860
861 old = avail;
862 avail = atomic_cmpxchg(&ctx->reqs_available,
863 avail, avail - ctx->req_batch);
864 } while (avail != old);
865
866 kcpu->reqs_available += ctx->req_batch;
867 }
868
869 ret = true;
870 kcpu->reqs_available--;
871out:
872 preempt_enable();
873 return ret;
874}
875
876/* aio_get_req
877 * Allocate a slot for an aio request.
878 * Returns NULL if no requests are free.
879 */
880static inline struct kiocb *aio_get_req(struct kioctx *ctx)
881{
882 struct kiocb *req;
883
884 if (!get_reqs_available(ctx))
885 return NULL;
886
887 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
888 if (unlikely(!req))
889 goto out_put;
890
891 percpu_ref_get(&ctx->reqs);
892
893 req->ki_ctx = ctx;
894 return req;
895out_put:
896 put_reqs_available(ctx, 1);
897 return NULL;
898}
899
900static void kiocb_free(struct kiocb *req)
901{
902 if (req->ki_filp)
903 fput(req->ki_filp);
904 if (req->ki_eventfd != NULL)
905 eventfd_ctx_put(req->ki_eventfd);
906 kmem_cache_free(kiocb_cachep, req);
907}
908
909static struct kioctx *lookup_ioctx(unsigned long ctx_id)
910{
911 struct aio_ring __user *ring = (void __user *)ctx_id;
912 struct mm_struct *mm = current->mm;
913 struct kioctx *ctx, *ret = NULL;
914 struct kioctx_table *table;
915 unsigned id;
916
917 if (get_user(id, &ring->id))
918 return NULL;
919
920 rcu_read_lock();
921 table = rcu_dereference(mm->ioctx_table);
922
923 if (!table || id >= table->nr)
924 goto out;
925
926 ctx = table->table[id];
927 if (ctx && ctx->user_id == ctx_id) {
928 percpu_ref_get(&ctx->users);
929 ret = ctx;
930 }
931out:
932 rcu_read_unlock();
933 return ret;
934}
935
936/* aio_complete
937 * Called when the io request on the given iocb is complete.
938 */
939void aio_complete(struct kiocb *iocb, long res, long res2)
940{
941 struct kioctx *ctx = iocb->ki_ctx;
942 struct aio_ring *ring;
943 struct io_event *ev_page, *event;
944 unsigned long flags;
945 unsigned tail, pos;
946
947 /*
948 * Special case handling for sync iocbs:
949 * - events go directly into the iocb for fast handling
950 * - the sync task with the iocb in its stack holds the single iocb
951 * ref, no other paths have a way to get another ref
952 * - the sync task helpfully left a reference to itself in the iocb
953 */
954 if (is_sync_kiocb(iocb)) {
955 iocb->ki_user_data = res;
956 smp_wmb();
957 iocb->ki_ctx = ERR_PTR(-EXDEV);
958 wake_up_process(iocb->ki_obj.tsk);
959 return;
960 }
961
962 if (iocb->ki_list.next) {
963 unsigned long flags;
964
965 spin_lock_irqsave(&ctx->ctx_lock, flags);
966 list_del(&iocb->ki_list);
967 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
968 }
969
970 /*
971 * Add a completion event to the ring buffer. Must be done holding
972 * ctx->completion_lock to prevent other code from messing with the tail
973 * pointer since we might be called from irq context.
974 */
975 spin_lock_irqsave(&ctx->completion_lock, flags);
976
977 tail = ctx->tail;
978 pos = tail + AIO_EVENTS_OFFSET;
979
980 if (++tail >= ctx->nr_events)
981 tail = 0;
982
983 ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
984 event = ev_page + pos % AIO_EVENTS_PER_PAGE;
985
986 event->obj = (u64)(unsigned long)iocb->ki_obj.user;
987 event->data = iocb->ki_user_data;
988 event->res = res;
989 event->res2 = res2;
990
991 kunmap_atomic(ev_page);
992 flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
993
994 pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
995 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
996 res, res2);
997
998 /* after flagging the request as done, we
999 * must never even look at it again
1000 */
1001 smp_wmb(); /* make event visible before updating tail */
1002
1003 ctx->tail = tail;
1004
1005 ring = kmap_atomic(ctx->ring_pages[0]);
1006 ring->tail = tail;
1007 kunmap_atomic(ring);
1008 flush_dcache_page(ctx->ring_pages[0]);
1009
1010 spin_unlock_irqrestore(&ctx->completion_lock, flags);
1011
1012 pr_debug("added to ring %p at [%u]\n", iocb, tail);
1013
1014 /*
1015 * Check if the user asked us to deliver the result through an
1016 * eventfd. The eventfd_signal() function is safe to be called
1017 * from IRQ context.
1018 */
1019 if (iocb->ki_eventfd != NULL)
1020 eventfd_signal(iocb->ki_eventfd, 1);
1021
1022 /* everything turned out well, dispose of the aiocb. */
1023 kiocb_free(iocb);
1024
1025 /*
1026 * We have to order our ring_info tail store above and test
1027 * of the wait list below outside the wait lock. This is
1028 * like in wake_up_bit() where clearing a bit has to be
1029 * ordered with the unlocked test.
1030 */
1031 smp_mb();
1032
1033 if (waitqueue_active(&ctx->wait))
1034 wake_up(&ctx->wait);
1035
1036 percpu_ref_put(&ctx->reqs);
1037}
1038EXPORT_SYMBOL(aio_complete);
1039
1040/* aio_read_events
1041 * Pull an event off of the ioctx's event ring. Returns the number of
1042 * events fetched
1043 */
1044static long aio_read_events_ring(struct kioctx *ctx,
1045 struct io_event __user *event, long nr)
1046{
1047 struct aio_ring *ring;
1048 unsigned head, tail, pos;
1049 long ret = 0;
1050 int copy_ret;
1051
1052 mutex_lock(&ctx->ring_lock);
1053
1054 /* Access to ->ring_pages here is protected by ctx->ring_lock. */
1055 ring = kmap_atomic(ctx->ring_pages[0]);
1056 head = ring->head;
1057 tail = ring->tail;
1058 kunmap_atomic(ring);
1059
1060 pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
1061
1062 if (head == tail)
1063 goto out;
1064
1065 while (ret < nr) {
1066 long avail;
1067 struct io_event *ev;
1068 struct page *page;
1069
1070 avail = (head <= tail ? tail : ctx->nr_events) - head;
1071 if (head == tail)
1072 break;
1073
1074 avail = min(avail, nr - ret);
1075 avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
1076 ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
1077
1078 pos = head + AIO_EVENTS_OFFSET;
1079 page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
1080 pos %= AIO_EVENTS_PER_PAGE;
1081
1082 ev = kmap(page);
1083 copy_ret = copy_to_user(event + ret, ev + pos,
1084 sizeof(*ev) * avail);
1085 kunmap(page);
1086
1087 if (unlikely(copy_ret)) {
1088 ret = -EFAULT;
1089 goto out;
1090 }
1091
1092 ret += avail;
1093 head += avail;
1094 head %= ctx->nr_events;
1095 }
1096
1097 ring = kmap_atomic(ctx->ring_pages[0]);
1098 ring->head = head;
1099 kunmap_atomic(ring);
1100 flush_dcache_page(ctx->ring_pages[0]);
1101
1102 pr_debug("%li h%u t%u\n", ret, head, tail);
1103
1104 put_reqs_available(ctx, ret);
1105out:
1106 mutex_unlock(&ctx->ring_lock);
1107
1108 return ret;
1109}
1110
1111static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
1112 struct io_event __user *event, long *i)
1113{
1114 long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
1115
1116 if (ret > 0)
1117 *i += ret;
1118
1119 if (unlikely(atomic_read(&ctx->dead)))
1120 ret = -EINVAL;
1121
1122 if (!*i)
1123 *i = ret;
1124
1125 return ret < 0 || *i >= min_nr;
1126}
1127
1128static long read_events(struct kioctx *ctx, long min_nr, long nr,
1129 struct io_event __user *event,
1130 struct timespec __user *timeout)
1131{
1132 ktime_t until = { .tv64 = KTIME_MAX };
1133 long ret = 0;
1134
1135 if (timeout) {
1136 struct timespec ts;
1137
1138 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
1139 return -EFAULT;
1140
1141 until = timespec_to_ktime(ts);
1142 }
1143
1144 /*
1145 * Note that aio_read_events() is being called as the conditional - i.e.
1146 * we're calling it after prepare_to_wait() has set task state to
1147 * TASK_INTERRUPTIBLE.
1148 *
1149 * But aio_read_events() can block, and if it blocks it's going to flip
1150 * the task state back to TASK_RUNNING.
1151 *
1152 * This should be ok, provided it doesn't flip the state back to
1153 * TASK_RUNNING and return 0 too much - that causes us to spin. That
1154 * will only happen if the mutex_lock() call blocks, and we then find
1155 * the ringbuffer empty. So in practice we should be ok, but it's
1156 * something to be aware of when touching this code.
1157 */
1158 wait_event_interruptible_hrtimeout(ctx->wait,
1159 aio_read_events(ctx, min_nr, nr, event, &ret), until);
1160
1161 if (!ret && signal_pending(current))
1162 ret = -EINTR;
1163
1164 return ret;
1165}
1166
1167/* sys_io_setup:
1168 * Create an aio_context capable of receiving at least nr_events.
1169 * ctxp must not point to an aio_context that already exists, and
1170 * must be initialized to 0 prior to the call. On successful
1171 * creation of the aio_context, *ctxp is filled in with the resulting
1172 * handle. May fail with -EINVAL if *ctxp is not initialized,
1173 * if the specified nr_events exceeds internal limits. May fail
1174 * with -EAGAIN if the specified nr_events exceeds the user's limit
1175 * of available events. May fail with -ENOMEM if insufficient kernel
1176 * resources are available. May fail with -EFAULT if an invalid
1177 * pointer is passed for ctxp. Will fail with -ENOSYS if not
1178 * implemented.
1179 */
1180SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1181{
1182 struct kioctx *ioctx = NULL;
1183 unsigned long ctx;
1184 long ret;
1185
1186 ret = get_user(ctx, ctxp);
1187 if (unlikely(ret))
1188 goto out;
1189
1190 ret = -EINVAL;
1191 if (unlikely(ctx || nr_events == 0)) {
1192 pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
1193 ctx, nr_events);
1194 goto out;
1195 }
1196
1197 ioctx = ioctx_alloc(nr_events);
1198 ret = PTR_ERR(ioctx);
1199 if (!IS_ERR(ioctx)) {
1200 ret = put_user(ioctx->user_id, ctxp);
1201 if (ret)
1202 kill_ioctx(current->mm, ioctx, NULL);
1203 percpu_ref_put(&ioctx->users);
1204 }
1205
1206out:
1207 return ret;
1208}
1209
1210/* sys_io_destroy:
1211 * Destroy the aio_context specified. May cancel any outstanding
1212 * AIOs and block on completion. Will fail with -ENOSYS if not
1213 * implemented. May fail with -EINVAL if the context pointed to
1214 * is invalid.
1215 */
1216SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1217{
1218 struct kioctx *ioctx = lookup_ioctx(ctx);
1219 if (likely(NULL != ioctx)) {
1220 struct completion requests_done =
1221 COMPLETION_INITIALIZER_ONSTACK(requests_done);
1222
1223 /* Pass requests_done to kill_ioctx() where it can be set
1224 * in a thread-safe way. If we try to set it here then we have
1225 * a race condition if two io_destroy() called simultaneously.
1226 */
1227 kill_ioctx(current->mm, ioctx, &requests_done);
1228 percpu_ref_put(&ioctx->users);
1229
1230 /* Wait until all IO for the context are done. Otherwise kernel
1231 * keep using user-space buffers even if user thinks the context
1232 * is destroyed.
1233 */
1234 wait_for_completion(&requests_done);
1235
1236 return 0;
1237 }
1238 pr_debug("EINVAL: io_destroy: invalid context id\n");
1239 return -EINVAL;
1240}
1241
1242typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *,
1243 unsigned long, loff_t);
1244
1245static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb,
1246 int rw, char __user *buf,
1247 unsigned long *nr_segs,
1248 struct iovec **iovec,
1249 bool compat)
1250{
1251 ssize_t ret;
1252
1253 *nr_segs = kiocb->ki_nbytes;
1254
1255#ifdef CONFIG_COMPAT
1256 if (compat)
1257 ret = compat_rw_copy_check_uvector(rw,
1258 (struct compat_iovec __user *)buf,
1259 *nr_segs, 1, *iovec, iovec);
1260 else
1261#endif
1262 ret = rw_copy_check_uvector(rw,
1263 (struct iovec __user *)buf,
1264 *nr_segs, 1, *iovec, iovec);
1265 if (ret < 0)
1266 return ret;
1267
1268 /* ki_nbytes now reflect bytes instead of segs */
1269 kiocb->ki_nbytes = ret;
1270 return 0;
1271}
1272
1273static ssize_t aio_setup_single_vector(struct kiocb *kiocb,
1274 int rw, char __user *buf,
1275 unsigned long *nr_segs,
1276 struct iovec *iovec)
1277{
1278 if (unlikely(!access_ok(!rw, buf, kiocb->ki_nbytes)))
1279 return -EFAULT;
1280
1281 iovec->iov_base = buf;
1282 iovec->iov_len = kiocb->ki_nbytes;
1283 *nr_segs = 1;
1284 return 0;
1285}
1286
1287/*
1288 * aio_setup_iocb:
1289 * Performs the initial checks and aio retry method
1290 * setup for the kiocb at the time of io submission.
1291 */
1292static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
1293 char __user *buf, bool compat)
1294{
1295 struct file *file = req->ki_filp;
1296 ssize_t ret;
1297 unsigned long nr_segs;
1298 int rw;
1299 fmode_t mode;
1300 aio_rw_op *rw_op;
1301 struct iovec inline_vec, *iovec = &inline_vec;
1302
1303 switch (opcode) {
1304 case IOCB_CMD_PREAD:
1305 case IOCB_CMD_PREADV:
1306 mode = FMODE_READ;
1307 rw = READ;
1308 rw_op = file->f_op->aio_read;
1309 goto rw_common;
1310
1311 case IOCB_CMD_PWRITE:
1312 case IOCB_CMD_PWRITEV:
1313 mode = FMODE_WRITE;
1314 rw = WRITE;
1315 rw_op = file->f_op->aio_write;
1316 goto rw_common;
1317rw_common:
1318 if (unlikely(!(file->f_mode & mode)))
1319 return -EBADF;
1320
1321 if (!rw_op)
1322 return -EINVAL;
1323
1324 ret = (opcode == IOCB_CMD_PREADV ||
1325 opcode == IOCB_CMD_PWRITEV)
1326 ? aio_setup_vectored_rw(req, rw, buf, &nr_segs,
1327 &iovec, compat)
1328 : aio_setup_single_vector(req, rw, buf, &nr_segs,
1329 iovec);
1330 if (!ret)
1331 ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
1332 if (ret < 0) {
1333 if (iovec != &inline_vec)
1334 kfree(iovec);
1335 return ret;
1336 }
1337
1338 req->ki_nbytes = ret;
1339
1340 /* XXX: move/kill - rw_verify_area()? */
1341 /* This matches the pread()/pwrite() logic */
1342 if (req->ki_pos < 0) {
1343 ret = -EINVAL;
1344 break;
1345 }
1346
1347 if (rw == WRITE)
1348 file_start_write(file);
1349
1350 ret = rw_op(req, iovec, nr_segs, req->ki_pos);
1351
1352 if (rw == WRITE)
1353 file_end_write(file);
1354 break;
1355
1356 case IOCB_CMD_FDSYNC:
1357 if (!file->f_op->aio_fsync)
1358 return -EINVAL;
1359
1360 ret = file->f_op->aio_fsync(req, 1);
1361 break;
1362
1363 case IOCB_CMD_FSYNC:
1364 if (!file->f_op->aio_fsync)
1365 return -EINVAL;
1366
1367 ret = file->f_op->aio_fsync(req, 0);
1368 break;
1369
1370 default:
1371 pr_debug("EINVAL: no operation provided\n");
1372 return -EINVAL;
1373 }
1374
1375 if (iovec != &inline_vec)
1376 kfree(iovec);
1377
1378 if (ret != -EIOCBQUEUED) {
1379 /*
1380 * There's no easy way to restart the syscall since other AIO's
1381 * may be already running. Just fail this IO with EINTR.
1382 */
1383 if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
1384 ret == -ERESTARTNOHAND ||
1385 ret == -ERESTART_RESTARTBLOCK))
1386 ret = -EINTR;
1387 aio_complete(req, ret, 0);
1388 }
1389
1390 return 0;
1391}
1392
1393static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1394 struct iocb *iocb, bool compat)
1395{
1396 struct kiocb *req;
1397 ssize_t ret;
1398
1399 /* enforce forwards compatibility on users */
1400 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
1401 pr_debug("EINVAL: reserve field set\n");
1402 return -EINVAL;
1403 }
1404
1405 /* prevent overflows */
1406 if (unlikely(
1407 (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
1408 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
1409 ((ssize_t)iocb->aio_nbytes < 0)
1410 )) {
1411 pr_debug("EINVAL: io_submit: overflow check\n");
1412 return -EINVAL;
1413 }
1414
1415 req = aio_get_req(ctx);
1416 if (unlikely(!req))
1417 return -EAGAIN;
1418
1419 req->ki_filp = fget(iocb->aio_fildes);
1420 if (unlikely(!req->ki_filp)) {
1421 ret = -EBADF;
1422 goto out_put_req;
1423 }
1424
1425 if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1426 /*
1427 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1428 * instance of the file* now. The file descriptor must be
1429 * an eventfd() fd, and will be signaled for each completed
1430 * event using the eventfd_signal() function.
1431 */
1432 req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
1433 if (IS_ERR(req->ki_eventfd)) {
1434 ret = PTR_ERR(req->ki_eventfd);
1435 req->ki_eventfd = NULL;
1436 goto out_put_req;
1437 }
1438 }
1439
1440 ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
1441 if (unlikely(ret)) {
1442 pr_debug("EFAULT: aio_key\n");
1443 goto out_put_req;
1444 }
1445
1446 req->ki_obj.user = user_iocb;
1447 req->ki_user_data = iocb->aio_data;
1448 req->ki_pos = iocb->aio_offset;
1449 req->ki_nbytes = iocb->aio_nbytes;
1450
1451 ret = aio_run_iocb(req, iocb->aio_lio_opcode,
1452 (char __user *)(unsigned long)iocb->aio_buf,
1453 compat);
1454 if (ret)
1455 goto out_put_req;
1456
1457 return 0;
1458out_put_req:
1459 put_reqs_available(ctx, 1);
1460 percpu_ref_put(&ctx->reqs);
1461 kiocb_free(req);
1462 return ret;
1463}
1464
1465long do_io_submit(aio_context_t ctx_id, long nr,
1466 struct iocb __user *__user *iocbpp, bool compat)
1467{
1468 struct kioctx *ctx;
1469 long ret = 0;
1470 int i = 0;
1471 struct blk_plug plug;
1472
1473 if (unlikely(nr < 0))
1474 return -EINVAL;
1475
1476 if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
1477 nr = LONG_MAX/sizeof(*iocbpp);
1478
1479 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1480 return -EFAULT;
1481
1482 ctx = lookup_ioctx(ctx_id);
1483 if (unlikely(!ctx)) {
1484 pr_debug("EINVAL: invalid context id\n");
1485 return -EINVAL;
1486 }
1487
1488 blk_start_plug(&plug);
1489
1490 /*
1491 * AKPM: should this return a partial result if some of the IOs were
1492 * successfully submitted?
1493 */
1494 for (i=0; i<nr; i++) {
1495 struct iocb __user *user_iocb;
1496 struct iocb tmp;
1497
1498 if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1499 ret = -EFAULT;
1500 break;
1501 }
1502
1503 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1504 ret = -EFAULT;
1505 break;
1506 }
1507
1508 ret = io_submit_one(ctx, user_iocb, &tmp, compat);
1509 if (ret)
1510 break;
1511 }
1512 blk_finish_plug(&plug);
1513
1514 percpu_ref_put(&ctx->users);
1515 return i ? i : ret;
1516}
1517
1518/* sys_io_submit:
1519 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1520 * the number of iocbs queued. May return -EINVAL if the aio_context
1521 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1522 * *iocbpp[0] is not properly initialized, if the operation specified
1523 * is invalid for the file descriptor in the iocb. May fail with
1524 * -EFAULT if any of the data structures point to invalid data. May
1525 * fail with -EBADF if the file descriptor specified in the first
1526 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1527 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1528 * fail with -ENOSYS if not implemented.
1529 */
1530SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
1531 struct iocb __user * __user *, iocbpp)
1532{
1533 return do_io_submit(ctx_id, nr, iocbpp, 0);
1534}
1535
1536/* lookup_kiocb
1537 * Finds a given iocb for cancellation.
1538 */
1539static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
1540 u32 key)
1541{
1542 struct list_head *pos;
1543
1544 assert_spin_locked(&ctx->ctx_lock);
1545
1546 if (key != KIOCB_KEY)
1547 return NULL;
1548
1549 /* TODO: use a hash or array, this sucks. */
1550 list_for_each(pos, &ctx->active_reqs) {
1551 struct kiocb *kiocb = list_kiocb(pos);
1552 if (kiocb->ki_obj.user == iocb)
1553 return kiocb;
1554 }
1555 return NULL;
1556}
1557
1558/* sys_io_cancel:
1559 * Attempts to cancel an iocb previously passed to io_submit. If
1560 * the operation is successfully cancelled, the resulting event is
1561 * copied into the memory pointed to by result without being placed
1562 * into the completion queue and 0 is returned. May fail with
1563 * -EFAULT if any of the data structures pointed to are invalid.
1564 * May fail with -EINVAL if aio_context specified by ctx_id is
1565 * invalid. May fail with -EAGAIN if the iocb specified was not
1566 * cancelled. Will fail with -ENOSYS if not implemented.
1567 */
1568SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
1569 struct io_event __user *, result)
1570{
1571 struct kioctx *ctx;
1572 struct kiocb *kiocb;
1573 u32 key;
1574 int ret;
1575
1576 ret = get_user(key, &iocb->aio_key);
1577 if (unlikely(ret))
1578 return -EFAULT;
1579
1580 ctx = lookup_ioctx(ctx_id);
1581 if (unlikely(!ctx))
1582 return -EINVAL;
1583
1584 spin_lock_irq(&ctx->ctx_lock);
1585
1586 kiocb = lookup_kiocb(ctx, iocb, key);
1587 if (kiocb)
1588 ret = kiocb_cancel(ctx, kiocb);
1589 else
1590 ret = -EINVAL;
1591
1592 spin_unlock_irq(&ctx->ctx_lock);
1593
1594 if (!ret) {
1595 /*
1596 * The result argument is no longer used - the io_event is
1597 * always delivered via the ring buffer. -EINPROGRESS indicates
1598 * cancellation is progress:
1599 */
1600 ret = -EINPROGRESS;
1601 }
1602
1603 percpu_ref_put(&ctx->users);
1604
1605 return ret;
1606}
1607
1608/* io_getevents:
1609 * Attempts to read at least min_nr events and up to nr events from
1610 * the completion queue for the aio_context specified by ctx_id. If
1611 * it succeeds, the number of read events is returned. May fail with
1612 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
1613 * out of range, if timeout is out of range. May fail with -EFAULT
1614 * if any of the memory specified is invalid. May return 0 or
1615 * < min_nr if the timeout specified by timeout has elapsed
1616 * before sufficient events are available, where timeout == NULL
1617 * specifies an infinite timeout. Note that the timeout pointed to by
1618 * timeout is relative. Will fail with -ENOSYS if not implemented.
1619 */
1620SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
1621 long, min_nr,
1622 long, nr,
1623 struct io_event __user *, events,
1624 struct timespec __user *, timeout)
1625{
1626 struct kioctx *ioctx = lookup_ioctx(ctx_id);
1627 long ret = -EINVAL;
1628
1629 if (likely(ioctx)) {
1630 if (likely(min_nr <= nr && min_nr >= 0))
1631 ret = read_events(ioctx, min_nr, nr, events, timeout);
1632 percpu_ref_put(&ioctx->users);
1633 }
1634 return ret;
1635}