blob: e4598d6d49ddea9311b73d716c1f92d91118b6ac [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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>
Badari Pulavarty027445c2006-09-30 23:28:46 -070018#include <linux/uio.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019
20#define DEBUG 0
21
22#include <linux/sched.h>
23#include <linux/fs.h>
24#include <linux/file.h>
25#include <linux/mm.h>
26#include <linux/mman.h>
27#include <linux/slab.h>
28#include <linux/timer.h>
29#include <linux/aio.h>
30#include <linux/highmem.h>
31#include <linux/workqueue.h>
32#include <linux/security.h>
33
34#include <asm/kmap_types.h>
35#include <asm/uaccess.h>
36#include <asm/mmu_context.h>
37
38#if DEBUG > 1
39#define dprintk printk
40#else
41#define dprintk(x...) do { ; } while (0)
42#endif
43
Linus Torvalds1da177e2005-04-16 15:20:36 -070044/*------ sysctl variables----*/
Zach Brownd55b5fd2005-11-07 00:59:31 -080045static DEFINE_SPINLOCK(aio_nr_lock);
46unsigned long aio_nr; /* current system wide number of aio requests */
47unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
Linus Torvalds1da177e2005-04-16 15:20:36 -070048/*----end sysctl variables---*/
49
Christoph Lametere18b8902006-12-06 20:33:20 -080050static struct kmem_cache *kiocb_cachep;
51static struct kmem_cache *kioctx_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
53static struct workqueue_struct *aio_wq;
54
55/* Used for rare fput completion. */
David Howells65f27f32006-11-22 14:55:48 +000056static void aio_fput_routine(struct work_struct *);
57static DECLARE_WORK(fput_work, aio_fput_routine);
Linus Torvalds1da177e2005-04-16 15:20:36 -070058
59static DEFINE_SPINLOCK(fput_lock);
Adrian Bunk25ee7e32005-04-25 08:18:14 -070060static LIST_HEAD(fput_head);
Linus Torvalds1da177e2005-04-16 15:20:36 -070061
David Howells65f27f32006-11-22 14:55:48 +000062static void aio_kick_handler(struct work_struct *);
Sébastien Duguc016e222005-06-28 20:44:59 -070063static void aio_queue_work(struct kioctx *);
Linus Torvalds1da177e2005-04-16 15:20:36 -070064
65/* aio_setup
66 * Creates the slab caches used by the aio routines, panic on
67 * failure as this is done early during the boot sequence.
68 */
69static int __init aio_setup(void)
70{
71 kiocb_cachep = kmem_cache_create("kiocb", sizeof(struct kiocb),
72 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
73 kioctx_cachep = kmem_cache_create("kioctx", sizeof(struct kioctx),
74 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
75
76 aio_wq = create_workqueue("aio");
77
78 pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page));
79
80 return 0;
81}
82
83static void aio_free_ring(struct kioctx *ctx)
84{
85 struct aio_ring_info *info = &ctx->ring_info;
86 long i;
87
88 for (i=0; i<info->nr_pages; i++)
89 put_page(info->ring_pages[i]);
90
91 if (info->mmap_size) {
92 down_write(&ctx->mm->mmap_sem);
93 do_munmap(ctx->mm, info->mmap_base, info->mmap_size);
94 up_write(&ctx->mm->mmap_sem);
95 }
96
97 if (info->ring_pages && info->ring_pages != info->internal_pages)
98 kfree(info->ring_pages);
99 info->ring_pages = NULL;
100 info->nr = 0;
101}
102
103static int aio_setup_ring(struct kioctx *ctx)
104{
105 struct aio_ring *ring;
106 struct aio_ring_info *info = &ctx->ring_info;
107 unsigned nr_events = ctx->max_reqs;
108 unsigned long size;
109 int nr_pages;
110
111 /* Compensate for the ring buffer's head/tail overlap entry */
112 nr_events += 2; /* 1 is required, 2 for good luck */
113
114 size = sizeof(struct aio_ring);
115 size += sizeof(struct io_event) * nr_events;
116 nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT;
117
118 if (nr_pages < 0)
119 return -EINVAL;
120
121 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event);
122
123 info->nr = 0;
124 info->ring_pages = info->internal_pages;
125 if (nr_pages > AIO_RING_PAGES) {
Oliver Neukum11b0b5a2006-03-25 03:08:13 -0800126 info->ring_pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 if (!info->ring_pages)
128 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 }
130
131 info->mmap_size = nr_pages * PAGE_SIZE;
132 dprintk("attempting mmap of %lu bytes\n", info->mmap_size);
133 down_write(&ctx->mm->mmap_sem);
134 info->mmap_base = do_mmap(NULL, 0, info->mmap_size,
Robert P. J. Daye10a4432007-02-10 01:42:56 -0800135 PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 0);
137 if (IS_ERR((void *)info->mmap_base)) {
138 up_write(&ctx->mm->mmap_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 info->mmap_size = 0;
140 aio_free_ring(ctx);
141 return -EAGAIN;
142 }
143
144 dprintk("mmap address: 0x%08lx\n", info->mmap_base);
145 info->nr_pages = get_user_pages(current, ctx->mm,
146 info->mmap_base, nr_pages,
147 1, 0, info->ring_pages, NULL);
148 up_write(&ctx->mm->mmap_sem);
149
150 if (unlikely(info->nr_pages != nr_pages)) {
151 aio_free_ring(ctx);
152 return -EAGAIN;
153 }
154
155 ctx->user_id = info->mmap_base;
156
157 info->nr = nr_events; /* trusted copy */
158
159 ring = kmap_atomic(info->ring_pages[0], KM_USER0);
160 ring->nr = nr_events; /* user copy */
161 ring->id = ctx->user_id;
162 ring->head = ring->tail = 0;
163 ring->magic = AIO_RING_MAGIC;
164 ring->compat_features = AIO_RING_COMPAT_FEATURES;
165 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
166 ring->header_length = sizeof(struct aio_ring);
167 kunmap_atomic(ring, KM_USER0);
168
169 return 0;
170}
171
172
173/* aio_ring_event: returns a pointer to the event at the given index from
174 * kmap_atomic(, km). Release the pointer with put_aio_ring_event();
175 */
176#define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
177#define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
178#define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
179
180#define aio_ring_event(info, nr, km) ({ \
181 unsigned pos = (nr) + AIO_EVENTS_OFFSET; \
182 struct io_event *__event; \
183 __event = kmap_atomic( \
184 (info)->ring_pages[pos / AIO_EVENTS_PER_PAGE], km); \
185 __event += pos % AIO_EVENTS_PER_PAGE; \
186 __event; \
187})
188
189#define put_aio_ring_event(event, km) do { \
190 struct io_event *__event = (event); \
191 (void)__event; \
192 kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK), km); \
193} while(0)
194
195/* ioctx_alloc
196 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
197 */
198static struct kioctx *ioctx_alloc(unsigned nr_events)
199{
200 struct mm_struct *mm;
201 struct kioctx *ctx;
202
203 /* Prevent overflows */
204 if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
205 (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
206 pr_debug("ENOMEM: nr_events too high\n");
207 return ERR_PTR(-EINVAL);
208 }
209
Zach Brownd55b5fd2005-11-07 00:59:31 -0800210 if ((unsigned long)nr_events > aio_max_nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211 return ERR_PTR(-EAGAIN);
212
Robert P. J. Dayc3762222007-02-10 01:45:03 -0800213 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 if (!ctx)
215 return ERR_PTR(-ENOMEM);
216
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 ctx->max_reqs = nr_events;
218 mm = ctx->mm = current->mm;
219 atomic_inc(&mm->mm_count);
220
221 atomic_set(&ctx->users, 1);
222 spin_lock_init(&ctx->ctx_lock);
223 spin_lock_init(&ctx->ring_info.ring_lock);
224 init_waitqueue_head(&ctx->wait);
225
226 INIT_LIST_HEAD(&ctx->active_reqs);
227 INIT_LIST_HEAD(&ctx->run_list);
David Howells65f27f32006-11-22 14:55:48 +0000228 INIT_DELAYED_WORK(&ctx->wq, aio_kick_handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229
230 if (aio_setup_ring(ctx) < 0)
231 goto out_freectx;
232
233 /* limit the number of system wide aios */
Zach Brownd55b5fd2005-11-07 00:59:31 -0800234 spin_lock(&aio_nr_lock);
235 if (aio_nr + ctx->max_reqs > aio_max_nr ||
236 aio_nr + ctx->max_reqs < aio_nr)
237 ctx->max_reqs = 0;
238 else
239 aio_nr += ctx->max_reqs;
240 spin_unlock(&aio_nr_lock);
241 if (ctx->max_reqs == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 goto out_cleanup;
243
244 /* now link into global list. kludge. FIXME */
245 write_lock(&mm->ioctx_list_lock);
246 ctx->next = mm->ioctx_list;
247 mm->ioctx_list = ctx;
248 write_unlock(&mm->ioctx_list_lock);
249
250 dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
251 ctx, ctx->user_id, current->mm, ctx->ring_info.nr);
252 return ctx;
253
254out_cleanup:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255 __put_ioctx(ctx);
256 return ERR_PTR(-EAGAIN);
257
258out_freectx:
259 mmdrop(mm);
260 kmem_cache_free(kioctx_cachep, ctx);
261 ctx = ERR_PTR(-ENOMEM);
262
263 dprintk("aio: error allocating ioctx %p\n", ctx);
264 return ctx;
265}
266
267/* aio_cancel_all
268 * Cancels all outstanding aio requests on an aio context. Used
269 * when the processes owning a context have all exited to encourage
270 * the rapid destruction of the kioctx.
271 */
272static void aio_cancel_all(struct kioctx *ctx)
273{
274 int (*cancel)(struct kiocb *, struct io_event *);
275 struct io_event res;
276 spin_lock_irq(&ctx->ctx_lock);
277 ctx->dead = 1;
278 while (!list_empty(&ctx->active_reqs)) {
279 struct list_head *pos = ctx->active_reqs.next;
280 struct kiocb *iocb = list_kiocb(pos);
281 list_del_init(&iocb->ki_list);
282 cancel = iocb->ki_cancel;
283 kiocbSetCancelled(iocb);
284 if (cancel) {
285 iocb->ki_users++;
286 spin_unlock_irq(&ctx->ctx_lock);
287 cancel(iocb, &res);
288 spin_lock_irq(&ctx->ctx_lock);
289 }
290 }
291 spin_unlock_irq(&ctx->ctx_lock);
292}
293
Adrian Bunk25ee7e32005-04-25 08:18:14 -0700294static void wait_for_all_aios(struct kioctx *ctx)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295{
296 struct task_struct *tsk = current;
297 DECLARE_WAITQUEUE(wait, tsk);
298
Ken Chendee11c22007-02-03 01:13:45 -0800299 spin_lock_irq(&ctx->ctx_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 if (!ctx->reqs_active)
Ken Chendee11c22007-02-03 01:13:45 -0800301 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302
303 add_wait_queue(&ctx->wait, &wait);
304 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
305 while (ctx->reqs_active) {
Ken Chendee11c22007-02-03 01:13:45 -0800306 spin_unlock_irq(&ctx->ctx_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307 schedule();
308 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
Ken Chendee11c22007-02-03 01:13:45 -0800309 spin_lock_irq(&ctx->ctx_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 }
311 __set_task_state(tsk, TASK_RUNNING);
312 remove_wait_queue(&ctx->wait, &wait);
Ken Chendee11c22007-02-03 01:13:45 -0800313
314out:
315 spin_unlock_irq(&ctx->ctx_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316}
317
318/* wait_on_sync_kiocb:
319 * Waits on the given sync kiocb to complete.
320 */
321ssize_t fastcall wait_on_sync_kiocb(struct kiocb *iocb)
322{
323 while (iocb->ki_users) {
324 set_current_state(TASK_UNINTERRUPTIBLE);
325 if (!iocb->ki_users)
326 break;
327 schedule();
328 }
329 __set_current_state(TASK_RUNNING);
330 return iocb->ki_user_data;
331}
332
333/* exit_aio: called when the last user of mm goes away. At this point,
334 * there is no way for any new requests to be submited or any of the
335 * io_* syscalls to be called on the context. However, there may be
336 * outstanding requests which hold references to the context; as they
337 * go away, they will call put_ioctx and release any pinned memory
338 * associated with the request (held via struct page * references).
339 */
340void fastcall exit_aio(struct mm_struct *mm)
341{
342 struct kioctx *ctx = mm->ioctx_list;
343 mm->ioctx_list = NULL;
344 while (ctx) {
345 struct kioctx *next = ctx->next;
346 ctx->next = NULL;
347 aio_cancel_all(ctx);
348
349 wait_for_all_aios(ctx);
350 /*
351 * this is an overkill, but ensures we don't leave
352 * the ctx on the aio_wq
353 */
354 flush_workqueue(aio_wq);
355
356 if (1 != atomic_read(&ctx->users))
357 printk(KERN_DEBUG
358 "exit_aio:ioctx still alive: %d %d %d\n",
359 atomic_read(&ctx->users), ctx->dead,
360 ctx->reqs_active);
361 put_ioctx(ctx);
362 ctx = next;
363 }
364}
365
366/* __put_ioctx
367 * Called when the last user of an aio context has gone away,
368 * and the struct needs to be freed.
369 */
370void fastcall __put_ioctx(struct kioctx *ctx)
371{
372 unsigned nr_events = ctx->max_reqs;
373
Eric Sesterhenn93e06b42006-11-30 05:29:23 +0100374 BUG_ON(ctx->reqs_active);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375
376 cancel_delayed_work(&ctx->wq);
377 flush_workqueue(aio_wq);
378 aio_free_ring(ctx);
379 mmdrop(ctx->mm);
380 ctx->mm = NULL;
381 pr_debug("__put_ioctx: freeing %p\n", ctx);
382 kmem_cache_free(kioctx_cachep, ctx);
383
Zach Brownd55b5fd2005-11-07 00:59:31 -0800384 if (nr_events) {
385 spin_lock(&aio_nr_lock);
386 BUG_ON(aio_nr - nr_events > aio_nr);
387 aio_nr -= nr_events;
388 spin_unlock(&aio_nr_lock);
389 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390}
391
392/* aio_get_req
393 * Allocate a slot for an aio request. Increments the users count
394 * of the kioctx so that the kioctx stays around until all requests are
395 * complete. Returns NULL if no requests are free.
396 *
397 * Returns with kiocb->users set to 2. The io submit code path holds
398 * an extra reference while submitting the i/o.
399 * This prevents races between the aio code path referencing the
400 * req (after submitting it) and aio_complete() freeing the req.
401 */
402static struct kiocb *FASTCALL(__aio_get_req(struct kioctx *ctx));
403static struct kiocb fastcall *__aio_get_req(struct kioctx *ctx)
404{
405 struct kiocb *req = NULL;
406 struct aio_ring *ring;
407 int okay = 0;
408
409 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
410 if (unlikely(!req))
411 return NULL;
412
Zach Brown4faa5282005-10-17 16:43:33 -0700413 req->ki_flags = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414 req->ki_users = 2;
415 req->ki_key = 0;
416 req->ki_ctx = ctx;
417 req->ki_cancel = NULL;
418 req->ki_retry = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419 req->ki_dtor = NULL;
420 req->private = NULL;
Badari Pulavartyeed4e512006-09-30 23:28:49 -0700421 req->ki_iovec = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 INIT_LIST_HEAD(&req->ki_run_list);
423
424 /* Check if the completion queue has enough free space to
425 * accept an event from this io.
426 */
427 spin_lock_irq(&ctx->ctx_lock);
428 ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0);
429 if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) {
430 list_add(&req->ki_list, &ctx->active_reqs);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 ctx->reqs_active++;
432 okay = 1;
433 }
434 kunmap_atomic(ring, KM_USER0);
435 spin_unlock_irq(&ctx->ctx_lock);
436
437 if (!okay) {
438 kmem_cache_free(kiocb_cachep, req);
439 req = NULL;
440 }
441
442 return req;
443}
444
445static inline struct kiocb *aio_get_req(struct kioctx *ctx)
446{
447 struct kiocb *req;
448 /* Handle a potential starvation case -- should be exceedingly rare as
449 * requests will be stuck on fput_head only if the aio_fput_routine is
450 * delayed and the requests were the last user of the struct file.
451 */
452 req = __aio_get_req(ctx);
453 if (unlikely(NULL == req)) {
454 aio_fput_routine(NULL);
455 req = __aio_get_req(ctx);
456 }
457 return req;
458}
459
460static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
461{
Zach Brownd00689a2005-11-13 16:07:34 -0800462 assert_spin_locked(&ctx->ctx_lock);
463
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 if (req->ki_dtor)
465 req->ki_dtor(req);
Badari Pulavartyeed4e512006-09-30 23:28:49 -0700466 if (req->ki_iovec != &req->ki_inline_vec)
467 kfree(req->ki_iovec);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468 kmem_cache_free(kiocb_cachep, req);
469 ctx->reqs_active--;
470
471 if (unlikely(!ctx->reqs_active && ctx->dead))
472 wake_up(&ctx->wait);
473}
474
David Howells65f27f32006-11-22 14:55:48 +0000475static void aio_fput_routine(struct work_struct *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476{
477 spin_lock_irq(&fput_lock);
478 while (likely(!list_empty(&fput_head))) {
479 struct kiocb *req = list_kiocb(fput_head.next);
480 struct kioctx *ctx = req->ki_ctx;
481
482 list_del(&req->ki_list);
483 spin_unlock_irq(&fput_lock);
484
485 /* Complete the fput */
486 __fput(req->ki_filp);
487
488 /* Link the iocb into the context's free list */
489 spin_lock_irq(&ctx->ctx_lock);
490 really_put_req(ctx, req);
491 spin_unlock_irq(&ctx->ctx_lock);
492
493 put_ioctx(ctx);
494 spin_lock_irq(&fput_lock);
495 }
496 spin_unlock_irq(&fput_lock);
497}
498
499/* __aio_put_req
500 * Returns true if this put was the last user of the request.
501 */
502static int __aio_put_req(struct kioctx *ctx, struct kiocb *req)
503{
504 dprintk(KERN_DEBUG "aio_put(%p): f_count=%d\n",
505 req, atomic_read(&req->ki_filp->f_count));
506
Zach Brownd00689a2005-11-13 16:07:34 -0800507 assert_spin_locked(&ctx->ctx_lock);
508
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509 req->ki_users --;
Eric Sesterhenn93e06b42006-11-30 05:29:23 +0100510 BUG_ON(req->ki_users < 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511 if (likely(req->ki_users))
512 return 0;
513 list_del(&req->ki_list); /* remove from active_reqs */
514 req->ki_cancel = NULL;
515 req->ki_retry = NULL;
516
517 /* Must be done under the lock to serialise against cancellation.
518 * Call this aio_fput as it duplicates fput via the fput_work.
519 */
Nick Piggin095975d2006-01-08 01:02:19 -0800520 if (unlikely(atomic_dec_and_test(&req->ki_filp->f_count))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 get_ioctx(ctx);
522 spin_lock(&fput_lock);
523 list_add(&req->ki_list, &fput_head);
524 spin_unlock(&fput_lock);
525 queue_work(aio_wq, &fput_work);
526 } else
527 really_put_req(ctx, req);
528 return 1;
529}
530
531/* aio_put_req
532 * Returns true if this put was the last user of the kiocb,
533 * false if the request is still in use.
534 */
535int fastcall aio_put_req(struct kiocb *req)
536{
537 struct kioctx *ctx = req->ki_ctx;
538 int ret;
539 spin_lock_irq(&ctx->ctx_lock);
540 ret = __aio_put_req(ctx, req);
541 spin_unlock_irq(&ctx->ctx_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542 return ret;
543}
544
545/* Lookup an ioctx id. ioctx_list is lockless for reads.
546 * FIXME: this is O(n) and is only suitable for development.
547 */
548struct kioctx *lookup_ioctx(unsigned long ctx_id)
549{
550 struct kioctx *ioctx;
551 struct mm_struct *mm;
552
553 mm = current->mm;
554 read_lock(&mm->ioctx_list_lock);
555 for (ioctx = mm->ioctx_list; ioctx; ioctx = ioctx->next)
556 if (likely(ioctx->user_id == ctx_id && !ioctx->dead)) {
557 get_ioctx(ioctx);
558 break;
559 }
560 read_unlock(&mm->ioctx_list_lock);
561
562 return ioctx;
563}
564
565/*
566 * use_mm
567 * Makes the calling kernel thread take on the specified
568 * mm context.
569 * Called by the retry thread execute retries within the
570 * iocb issuer's mm context, so that copy_from/to_user
571 * operations work seamlessly for aio.
572 * (Note: this routine is intended to be called only
573 * from a kernel thread context)
574 */
575static void use_mm(struct mm_struct *mm)
576{
577 struct mm_struct *active_mm;
578 struct task_struct *tsk = current;
579
580 task_lock(tsk);
581 tsk->flags |= PF_BORROWED_MM;
582 active_mm = tsk->active_mm;
583 atomic_inc(&mm->mm_count);
584 tsk->mm = mm;
585 tsk->active_mm = mm;
Paolo 'Blaisorblade' Giarrusso1e40cd32005-09-03 15:57:25 -0700586 /*
587 * Note that on UML this *requires* PF_BORROWED_MM to be set, otherwise
588 * it won't work. Update it accordingly if you change it here
589 */
Jeremy Fitzhardinge90aef122006-12-13 00:34:49 -0800590 switch_mm(active_mm, mm, tsk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 task_unlock(tsk);
592
593 mmdrop(active_mm);
594}
595
596/*
597 * unuse_mm
598 * Reverses the effect of use_mm, i.e. releases the
599 * specified mm context which was earlier taken on
600 * by the calling kernel thread
601 * (Note: this routine is intended to be called only
602 * from a kernel thread context)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603 */
Adrian Bunk25ee7e32005-04-25 08:18:14 -0700604static void unuse_mm(struct mm_struct *mm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605{
606 struct task_struct *tsk = current;
607
608 task_lock(tsk);
609 tsk->flags &= ~PF_BORROWED_MM;
610 tsk->mm = NULL;
611 /* active_mm is still 'mm' */
612 enter_lazy_tlb(mm, tsk);
613 task_unlock(tsk);
614}
615
616/*
617 * Queue up a kiocb to be retried. Assumes that the kiocb
618 * has already been marked as kicked, and places it on
619 * the retry run list for the corresponding ioctx, if it
620 * isn't already queued. Returns 1 if it actually queued
621 * the kiocb (to tell the caller to activate the work
622 * queue to process it), or 0, if it found that it was
623 * already queued.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700624 */
625static inline int __queue_kicked_iocb(struct kiocb *iocb)
626{
627 struct kioctx *ctx = iocb->ki_ctx;
628
Zach Brownd00689a2005-11-13 16:07:34 -0800629 assert_spin_locked(&ctx->ctx_lock);
630
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631 if (list_empty(&iocb->ki_run_list)) {
632 list_add_tail(&iocb->ki_run_list,
633 &ctx->run_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634 return 1;
635 }
636 return 0;
637}
638
639/* aio_run_iocb
640 * This is the core aio execution routine. It is
641 * invoked both for initial i/o submission and
642 * subsequent retries via the aio_kick_handler.
643 * Expects to be invoked with iocb->ki_ctx->lock
Andreas Mohrd6e05ed2006-06-26 18:35:02 +0200644 * already held. The lock is released and reacquired
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645 * as needed during processing.
646 *
647 * Calls the iocb retry method (already setup for the
648 * iocb on initial submission) for operation specific
649 * handling, but takes care of most of common retry
650 * execution details for a given iocb. The retry method
651 * needs to be non-blocking as far as possible, to avoid
652 * holding up other iocbs waiting to be serviced by the
653 * retry kernel thread.
654 *
655 * The trickier parts in this code have to do with
656 * ensuring that only one retry instance is in progress
657 * for a given iocb at any time. Providing that guarantee
658 * simplifies the coding of individual aio operations as
659 * it avoids various potential races.
660 */
661static ssize_t aio_run_iocb(struct kiocb *iocb)
662{
663 struct kioctx *ctx = iocb->ki_ctx;
664 ssize_t (*retry)(struct kiocb *);
665 ssize_t ret;
666
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667 if (!(retry = iocb->ki_retry)) {
668 printk("aio_run_iocb: iocb->ki_retry = NULL\n");
669 return 0;
670 }
671
672 /*
673 * We don't want the next retry iteration for this
674 * operation to start until this one has returned and
675 * updated the iocb state. However, wait_queue functions
676 * can trigger a kick_iocb from interrupt context in the
677 * meantime, indicating that data is available for the next
678 * iteration. We want to remember that and enable the
679 * next retry iteration _after_ we are through with
680 * this one.
681 *
682 * So, in order to be able to register a "kick", but
683 * prevent it from being queued now, we clear the kick
684 * flag, but make the kick code *think* that the iocb is
685 * still on the run list until we are actually done.
686 * When we are done with this iteration, we check if
687 * the iocb was kicked in the meantime and if so, queue
688 * it up afresh.
689 */
690
691 kiocbClearKicked(iocb);
692
693 /*
694 * This is so that aio_complete knows it doesn't need to
695 * pull the iocb off the run list (We can't just call
696 * INIT_LIST_HEAD because we don't want a kick_iocb to
697 * queue this on the run list yet)
698 */
699 iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL;
700 spin_unlock_irq(&ctx->ctx_lock);
701
702 /* Quit retrying if the i/o has been cancelled */
703 if (kiocbIsCancelled(iocb)) {
704 ret = -EINTR;
705 aio_complete(iocb, ret, 0);
706 /* must not access the iocb after this */
707 goto out;
708 }
709
710 /*
711 * Now we are all set to call the retry method in async
712 * context. By setting this thread's io_wait context
713 * to point to the wait queue entry inside the currently
714 * running iocb for the duration of the retry, we ensure
715 * that async notification wakeups are queued by the
716 * operation instead of blocking waits, and when notified,
717 * cause the iocb to be kicked for continuation (through
718 * the aio_wake_function callback).
719 */
720 BUG_ON(current->io_wait != NULL);
721 current->io_wait = &iocb->ki_wait;
722 ret = retry(iocb);
723 current->io_wait = NULL;
724
Zach Brown897f15f2005-09-30 11:58:55 -0700725 if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) {
726 BUG_ON(!list_empty(&iocb->ki_wait.task_list));
727 aio_complete(iocb, ret, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728 }
729out:
730 spin_lock_irq(&ctx->ctx_lock);
731
732 if (-EIOCBRETRY == ret) {
733 /*
734 * OK, now that we are done with this iteration
735 * and know that there is more left to go,
736 * this is where we let go so that a subsequent
737 * "kick" can start the next iteration
738 */
739
740 /* will make __queue_kicked_iocb succeed from here on */
741 INIT_LIST_HEAD(&iocb->ki_run_list);
742 /* we must queue the next iteration ourselves, if it
743 * has already been kicked */
744 if (kiocbIsKicked(iocb)) {
745 __queue_kicked_iocb(iocb);
Sébastien Duguc016e222005-06-28 20:44:59 -0700746
747 /*
748 * __queue_kicked_iocb will always return 1 here, because
749 * iocb->ki_run_list is empty at this point so it should
750 * be safe to unconditionally queue the context into the
751 * work queue.
752 */
753 aio_queue_work(ctx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700754 }
755 }
756 return ret;
757}
758
759/*
760 * __aio_run_iocbs:
761 * Process all pending retries queued on the ioctx
762 * run list.
763 * Assumes it is operating within the aio issuer's mm
Zach Brownd00689a2005-11-13 16:07:34 -0800764 * context.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 */
766static int __aio_run_iocbs(struct kioctx *ctx)
767{
768 struct kiocb *iocb;
Oleg Nesterov626ab0e2006-06-23 02:05:55 -0700769 struct list_head run_list;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770
Zach Brownd00689a2005-11-13 16:07:34 -0800771 assert_spin_locked(&ctx->ctx_lock);
772
Oleg Nesterov626ab0e2006-06-23 02:05:55 -0700773 list_replace_init(&ctx->run_list, &run_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774 while (!list_empty(&run_list)) {
775 iocb = list_entry(run_list.next, struct kiocb,
776 ki_run_list);
777 list_del(&iocb->ki_run_list);
778 /*
779 * Hold an extra reference while retrying i/o.
780 */
781 iocb->ki_users++; /* grab extra reference */
782 aio_run_iocb(iocb);
Ken Chendee11c22007-02-03 01:13:45 -0800783 __aio_put_req(ctx, iocb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700785 if (!list_empty(&ctx->run_list))
786 return 1;
787 return 0;
788}
789
790static void aio_queue_work(struct kioctx * ctx)
791{
792 unsigned long timeout;
793 /*
794 * if someone is waiting, get the work started right
795 * away, otherwise, use a longer delay
796 */
797 smp_mb();
798 if (waitqueue_active(&ctx->wait))
799 timeout = 1;
800 else
801 timeout = HZ/10;
802 queue_delayed_work(aio_wq, &ctx->wq, timeout);
803}
804
805
806/*
807 * aio_run_iocbs:
808 * Process all pending retries queued on the ioctx
809 * run list.
810 * Assumes it is operating within the aio issuer's mm
811 * context.
812 */
813static inline void aio_run_iocbs(struct kioctx *ctx)
814{
815 int requeue;
816
817 spin_lock_irq(&ctx->ctx_lock);
818
819 requeue = __aio_run_iocbs(ctx);
820 spin_unlock_irq(&ctx->ctx_lock);
821 if (requeue)
822 aio_queue_work(ctx);
823}
824
825/*
826 * just like aio_run_iocbs, but keeps running them until
827 * the list stays empty
828 */
829static inline void aio_run_all_iocbs(struct kioctx *ctx)
830{
831 spin_lock_irq(&ctx->ctx_lock);
832 while (__aio_run_iocbs(ctx))
833 ;
834 spin_unlock_irq(&ctx->ctx_lock);
835}
836
837/*
838 * aio_kick_handler:
839 * Work queue handler triggered to process pending
840 * retries on an ioctx. Takes on the aio issuer's
841 * mm context before running the iocbs, so that
842 * copy_xxx_user operates on the issuer's address
843 * space.
844 * Run on aiod's context.
845 */
David Howells65f27f32006-11-22 14:55:48 +0000846static void aio_kick_handler(struct work_struct *work)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700847{
David Howells65f27f32006-11-22 14:55:48 +0000848 struct kioctx *ctx = container_of(work, struct kioctx, wq.work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700849 mm_segment_t oldfs = get_fs();
Zach Brown1ebb1102006-12-29 16:47:02 -0800850 struct mm_struct *mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851 int requeue;
852
853 set_fs(USER_DS);
854 use_mm(ctx->mm);
855 spin_lock_irq(&ctx->ctx_lock);
856 requeue =__aio_run_iocbs(ctx);
Zach Brown1ebb1102006-12-29 16:47:02 -0800857 mm = ctx->mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858 spin_unlock_irq(&ctx->ctx_lock);
Zach Brown1ebb1102006-12-29 16:47:02 -0800859 unuse_mm(mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700860 set_fs(oldfs);
861 /*
862 * we're in a worker thread already, don't use queue_delayed_work,
863 */
864 if (requeue)
David Howells52bad642006-11-22 14:54:01 +0000865 queue_delayed_work(aio_wq, &ctx->wq, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700866}
867
868
869/*
870 * Called by kick_iocb to queue the kiocb for retry
871 * and if required activate the aio work queue to process
872 * it
873 */
Zach Brown998765e2005-09-30 11:58:54 -0700874static void try_queue_kicked_iocb(struct kiocb *iocb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875{
876 struct kioctx *ctx = iocb->ki_ctx;
877 unsigned long flags;
878 int run = 0;
879
Zach Brown998765e2005-09-30 11:58:54 -0700880 /* We're supposed to be the only path putting the iocb back on the run
881 * list. If we find that the iocb is *back* on a wait queue already
882 * than retry has happened before we could queue the iocb. This also
883 * means that the retry could have completed and freed our iocb, no
884 * good. */
885 BUG_ON((!list_empty(&iocb->ki_wait.task_list)));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700886
887 spin_lock_irqsave(&ctx->ctx_lock, flags);
Zach Brown998765e2005-09-30 11:58:54 -0700888 /* set this inside the lock so that we can't race with aio_run_iocb()
889 * testing it and putting the iocb on the run list under the lock */
890 if (!kiocbTryKick(iocb))
891 run = __queue_kicked_iocb(iocb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700892 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
Ken Chen644d3a02005-05-01 08:59:15 -0700893 if (run)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700894 aio_queue_work(ctx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895}
896
897/*
898 * kick_iocb:
899 * Called typically from a wait queue callback context
900 * (aio_wake_function) to trigger a retry of the iocb.
901 * The retry is usually executed by aio workqueue
902 * threads (See aio_kick_handler).
903 */
904void fastcall kick_iocb(struct kiocb *iocb)
905{
906 /* sync iocbs are easy: they can only ever be executing from a
907 * single context. */
908 if (is_sync_kiocb(iocb)) {
909 kiocbSetKicked(iocb);
910 wake_up_process(iocb->ki_obj.tsk);
911 return;
912 }
913
Zach Brown998765e2005-09-30 11:58:54 -0700914 try_queue_kicked_iocb(iocb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700915}
916EXPORT_SYMBOL(kick_iocb);
917
918/* aio_complete
919 * Called when the io request on the given iocb is complete.
920 * Returns true if this is the last user of the request. The
921 * only other user of the request can be the cancellation code.
922 */
923int fastcall aio_complete(struct kiocb *iocb, long res, long res2)
924{
925 struct kioctx *ctx = iocb->ki_ctx;
926 struct aio_ring_info *info;
927 struct aio_ring *ring;
928 struct io_event *event;
929 unsigned long flags;
930 unsigned long tail;
931 int ret;
932
Zach Brown20dcae32005-11-13 16:07:33 -0800933 /*
934 * Special case handling for sync iocbs:
935 * - events go directly into the iocb for fast handling
936 * - the sync task with the iocb in its stack holds the single iocb
937 * ref, no other paths have a way to get another ref
938 * - the sync task helpfully left a reference to itself in the iocb
Linus Torvalds1da177e2005-04-16 15:20:36 -0700939 */
940 if (is_sync_kiocb(iocb)) {
Zach Brown20dcae32005-11-13 16:07:33 -0800941 BUG_ON(iocb->ki_users != 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942 iocb->ki_user_data = res;
Zach Brown20dcae32005-11-13 16:07:33 -0800943 iocb->ki_users = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944 wake_up_process(iocb->ki_obj.tsk);
Zach Brown20dcae32005-11-13 16:07:33 -0800945 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700946 }
947
948 info = &ctx->ring_info;
949
950 /* add a completion event to the ring buffer.
951 * must be done holding ctx->ctx_lock to prevent
952 * other code from messing with the tail
953 * pointer since we might be called from irq
954 * context.
955 */
956 spin_lock_irqsave(&ctx->ctx_lock, flags);
957
958 if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list))
959 list_del_init(&iocb->ki_run_list);
960
961 /*
962 * cancelled requests don't get events, userland was given one
963 * when the event got cancelled.
964 */
965 if (kiocbIsCancelled(iocb))
966 goto put_rq;
967
968 ring = kmap_atomic(info->ring_pages[0], KM_IRQ1);
969
970 tail = info->tail;
971 event = aio_ring_event(info, tail, KM_IRQ0);
Ken Chen4bf69b22005-05-01 08:59:15 -0700972 if (++tail >= info->nr)
973 tail = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974
975 event->obj = (u64)(unsigned long)iocb->ki_obj.user;
976 event->data = iocb->ki_user_data;
977 event->res = res;
978 event->res2 = res2;
979
980 dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n",
981 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
982 res, res2);
983
984 /* after flagging the request as done, we
985 * must never even look at it again
986 */
987 smp_wmb(); /* make event visible before updating tail */
988
989 info->tail = tail;
990 ring->tail = tail;
991
992 put_aio_ring_event(event, KM_IRQ0);
993 kunmap_atomic(ring, KM_IRQ1);
994
995 pr_debug("added to ring %p at [%lu]\n", iocb, tail);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700996put_rq:
997 /* everything turned out well, dispose of the aiocb. */
998 ret = __aio_put_req(ctx, iocb);
999
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000 if (waitqueue_active(&ctx->wait))
1001 wake_up(&ctx->wait);
1002
Ken Chendee11c22007-02-03 01:13:45 -08001003 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001004 return ret;
1005}
1006
1007/* aio_read_evt
1008 * Pull an event off of the ioctx's event ring. Returns the number of
1009 * events fetched (0 or 1 ;-)
1010 * FIXME: make this use cmpxchg.
1011 * TODO: make the ringbuffer user mmap()able (requires FIXME).
1012 */
1013static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent)
1014{
1015 struct aio_ring_info *info = &ioctx->ring_info;
1016 struct aio_ring *ring;
1017 unsigned long head;
1018 int ret = 0;
1019
1020 ring = kmap_atomic(info->ring_pages[0], KM_USER0);
1021 dprintk("in aio_read_evt h%lu t%lu m%lu\n",
1022 (unsigned long)ring->head, (unsigned long)ring->tail,
1023 (unsigned long)ring->nr);
1024
1025 if (ring->head == ring->tail)
1026 goto out;
1027
1028 spin_lock(&info->ring_lock);
1029
1030 head = ring->head % info->nr;
1031 if (head != ring->tail) {
1032 struct io_event *evp = aio_ring_event(info, head, KM_USER1);
1033 *ent = *evp;
1034 head = (head + 1) % info->nr;
1035 smp_mb(); /* finish reading the event before updatng the head */
1036 ring->head = head;
1037 ret = 1;
1038 put_aio_ring_event(evp, KM_USER1);
1039 }
1040 spin_unlock(&info->ring_lock);
1041
1042out:
1043 kunmap_atomic(ring, KM_USER0);
1044 dprintk("leaving aio_read_evt: %d h%lu t%lu\n", ret,
1045 (unsigned long)ring->head, (unsigned long)ring->tail);
1046 return ret;
1047}
1048
1049struct aio_timeout {
1050 struct timer_list timer;
1051 int timed_out;
1052 struct task_struct *p;
1053};
1054
1055static void timeout_func(unsigned long data)
1056{
1057 struct aio_timeout *to = (struct aio_timeout *)data;
1058
1059 to->timed_out = 1;
1060 wake_up_process(to->p);
1061}
1062
1063static inline void init_timeout(struct aio_timeout *to)
1064{
1065 init_timer(&to->timer);
1066 to->timer.data = (unsigned long)to;
1067 to->timer.function = timeout_func;
1068 to->timed_out = 0;
1069 to->p = current;
1070}
1071
1072static inline void set_timeout(long start_jiffies, struct aio_timeout *to,
1073 const struct timespec *ts)
1074{
1075 to->timer.expires = start_jiffies + timespec_to_jiffies(ts);
1076 if (time_after(to->timer.expires, jiffies))
1077 add_timer(&to->timer);
1078 else
1079 to->timed_out = 1;
1080}
1081
1082static inline void clear_timeout(struct aio_timeout *to)
1083{
1084 del_singleshot_timer_sync(&to->timer);
1085}
1086
1087static int read_events(struct kioctx *ctx,
1088 long min_nr, long nr,
1089 struct io_event __user *event,
1090 struct timespec __user *timeout)
1091{
1092 long start_jiffies = jiffies;
1093 struct task_struct *tsk = current;
1094 DECLARE_WAITQUEUE(wait, tsk);
1095 int ret;
1096 int i = 0;
1097 struct io_event ent;
1098 struct aio_timeout to;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099 int retry = 0;
1100
1101 /* needed to zero any padding within an entry (there shouldn't be
1102 * any, but C is fun!
1103 */
1104 memset(&ent, 0, sizeof(ent));
1105retry:
1106 ret = 0;
1107 while (likely(i < nr)) {
1108 ret = aio_read_evt(ctx, &ent);
1109 if (unlikely(ret <= 0))
1110 break;
1111
1112 dprintk("read event: %Lx %Lx %Lx %Lx\n",
1113 ent.data, ent.obj, ent.res, ent.res2);
1114
1115 /* Could we split the check in two? */
1116 ret = -EFAULT;
1117 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
1118 dprintk("aio: lost an event due to EFAULT.\n");
1119 break;
1120 }
1121 ret = 0;
1122
1123 /* Good, event copied to userland, update counts. */
1124 event ++;
1125 i ++;
1126 }
1127
1128 if (min_nr <= i)
1129 return i;
1130 if (ret)
1131 return ret;
1132
1133 /* End fast path */
1134
1135 /* racey check, but it gets redone */
1136 if (!retry && unlikely(!list_empty(&ctx->run_list))) {
1137 retry = 1;
1138 aio_run_all_iocbs(ctx);
1139 goto retry;
1140 }
1141
1142 init_timeout(&to);
1143 if (timeout) {
1144 struct timespec ts;
1145 ret = -EFAULT;
1146 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
1147 goto out;
1148
1149 set_timeout(start_jiffies, &to, &ts);
1150 }
1151
1152 while (likely(i < nr)) {
1153 add_wait_queue_exclusive(&ctx->wait, &wait);
1154 do {
1155 set_task_state(tsk, TASK_INTERRUPTIBLE);
1156 ret = aio_read_evt(ctx, &ent);
1157 if (ret)
1158 break;
1159 if (min_nr <= i)
1160 break;
1161 ret = 0;
1162 if (to.timed_out) /* Only check after read evt */
1163 break;
1164 schedule();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001165 if (signal_pending(tsk)) {
1166 ret = -EINTR;
1167 break;
1168 }
1169 /*ret = aio_read_evt(ctx, &ent);*/
1170 } while (1) ;
1171
1172 set_task_state(tsk, TASK_RUNNING);
1173 remove_wait_queue(&ctx->wait, &wait);
1174
1175 if (unlikely(ret <= 0))
1176 break;
1177
1178 ret = -EFAULT;
1179 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
1180 dprintk("aio: lost an event due to EFAULT.\n");
1181 break;
1182 }
1183
1184 /* Good, event copied to userland, update counts. */
1185 event ++;
1186 i ++;
1187 }
1188
1189 if (timeout)
1190 clear_timeout(&to);
1191out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192 return i ? i : ret;
1193}
1194
1195/* Take an ioctx and remove it from the list of ioctx's. Protects
1196 * against races with itself via ->dead.
1197 */
1198static void io_destroy(struct kioctx *ioctx)
1199{
1200 struct mm_struct *mm = current->mm;
1201 struct kioctx **tmp;
1202 int was_dead;
1203
1204 /* delete the entry from the list is someone else hasn't already */
1205 write_lock(&mm->ioctx_list_lock);
1206 was_dead = ioctx->dead;
1207 ioctx->dead = 1;
1208 for (tmp = &mm->ioctx_list; *tmp && *tmp != ioctx;
1209 tmp = &(*tmp)->next)
1210 ;
1211 if (*tmp)
1212 *tmp = ioctx->next;
1213 write_unlock(&mm->ioctx_list_lock);
1214
1215 dprintk("aio_release(%p)\n", ioctx);
1216 if (likely(!was_dead))
1217 put_ioctx(ioctx); /* twice for the list */
1218
1219 aio_cancel_all(ioctx);
1220 wait_for_all_aios(ioctx);
1221 put_ioctx(ioctx); /* once for the lookup */
1222}
1223
1224/* sys_io_setup:
1225 * Create an aio_context capable of receiving at least nr_events.
1226 * ctxp must not point to an aio_context that already exists, and
1227 * must be initialized to 0 prior to the call. On successful
1228 * creation of the aio_context, *ctxp is filled in with the resulting
1229 * handle. May fail with -EINVAL if *ctxp is not initialized,
1230 * if the specified nr_events exceeds internal limits. May fail
1231 * with -EAGAIN if the specified nr_events exceeds the user's limit
1232 * of available events. May fail with -ENOMEM if insufficient kernel
1233 * resources are available. May fail with -EFAULT if an invalid
1234 * pointer is passed for ctxp. Will fail with -ENOSYS if not
1235 * implemented.
1236 */
1237asmlinkage long sys_io_setup(unsigned nr_events, aio_context_t __user *ctxp)
1238{
1239 struct kioctx *ioctx = NULL;
1240 unsigned long ctx;
1241 long ret;
1242
1243 ret = get_user(ctx, ctxp);
1244 if (unlikely(ret))
1245 goto out;
1246
1247 ret = -EINVAL;
Zach Brownd55b5fd2005-11-07 00:59:31 -08001248 if (unlikely(ctx || nr_events == 0)) {
1249 pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
1250 ctx, nr_events);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001251 goto out;
1252 }
1253
1254 ioctx = ioctx_alloc(nr_events);
1255 ret = PTR_ERR(ioctx);
1256 if (!IS_ERR(ioctx)) {
1257 ret = put_user(ioctx->user_id, ctxp);
1258 if (!ret)
1259 return 0;
1260
1261 get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */
1262 io_destroy(ioctx);
1263 }
1264
1265out:
1266 return ret;
1267}
1268
1269/* sys_io_destroy:
1270 * Destroy the aio_context specified. May cancel any outstanding
1271 * AIOs and block on completion. Will fail with -ENOSYS if not
1272 * implemented. May fail with -EFAULT if the context pointed to
1273 * is invalid.
1274 */
1275asmlinkage long sys_io_destroy(aio_context_t ctx)
1276{
1277 struct kioctx *ioctx = lookup_ioctx(ctx);
1278 if (likely(NULL != ioctx)) {
1279 io_destroy(ioctx);
1280 return 0;
1281 }
1282 pr_debug("EINVAL: io_destroy: invalid context id\n");
1283 return -EINVAL;
1284}
1285
Badari Pulavartyeed4e512006-09-30 23:28:49 -07001286static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret)
1287{
1288 struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg];
1289
1290 BUG_ON(ret <= 0);
1291
1292 while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) {
1293 ssize_t this = min((ssize_t)iov->iov_len, ret);
1294 iov->iov_base += this;
1295 iov->iov_len -= this;
1296 iocb->ki_left -= this;
1297 ret -= this;
1298 if (iov->iov_len == 0) {
1299 iocb->ki_cur_seg++;
1300 iov++;
1301 }
1302 }
1303
1304 /* the caller should not have done more io than what fit in
1305 * the remaining iovecs */
1306 BUG_ON(ret > 0 && iocb->ki_left == 0);
1307}
1308
1309static ssize_t aio_rw_vect_retry(struct kiocb *iocb)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001310{
1311 struct file *file = iocb->ki_filp;
1312 struct address_space *mapping = file->f_mapping;
1313 struct inode *inode = mapping->host;
Badari Pulavartyeed4e512006-09-30 23:28:49 -07001314 ssize_t (*rw_op)(struct kiocb *, const struct iovec *,
1315 unsigned long, loff_t);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001316 ssize_t ret = 0;
Badari Pulavartyeed4e512006-09-30 23:28:49 -07001317 unsigned short opcode;
1318
1319 if ((iocb->ki_opcode == IOCB_CMD_PREADV) ||
1320 (iocb->ki_opcode == IOCB_CMD_PREAD)) {
1321 rw_op = file->f_op->aio_read;
1322 opcode = IOCB_CMD_PREADV;
1323 } else {
1324 rw_op = file->f_op->aio_write;
1325 opcode = IOCB_CMD_PWRITEV;
1326 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001327
Zach Brown897f15f2005-09-30 11:58:55 -07001328 do {
Badari Pulavartyeed4e512006-09-30 23:28:49 -07001329 ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg],
1330 iocb->ki_nr_segs - iocb->ki_cur_seg,
1331 iocb->ki_pos);
1332 if (ret > 0)
1333 aio_advance_iovec(iocb, ret);
Badari Pulavarty027445c2006-09-30 23:28:46 -07001334
Badari Pulavartyeed4e512006-09-30 23:28:49 -07001335 /* retry all partial writes. retry partial reads as long as its a
1336 * regular file. */
Zach Brown353fb072005-09-30 11:58:56 -07001337 } while (ret > 0 && iocb->ki_left > 0 &&
Badari Pulavartyeed4e512006-09-30 23:28:49 -07001338 (opcode == IOCB_CMD_PWRITEV ||
1339 (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001340
1341 /* This means we must have transferred all that we could */
1342 /* No need to retry anymore */
1343 if ((ret == 0) || (iocb->ki_left == 0))
1344 ret = iocb->ki_nbytes - iocb->ki_left;
1345
1346 return ret;
1347}
1348
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349static ssize_t aio_fdsync(struct kiocb *iocb)
1350{
1351 struct file *file = iocb->ki_filp;
1352 ssize_t ret = -EINVAL;
1353
1354 if (file->f_op->aio_fsync)
1355 ret = file->f_op->aio_fsync(iocb, 1);
1356 return ret;
1357}
1358
1359static ssize_t aio_fsync(struct kiocb *iocb)
1360{
1361 struct file *file = iocb->ki_filp;
1362 ssize_t ret = -EINVAL;
1363
1364 if (file->f_op->aio_fsync)
1365 ret = file->f_op->aio_fsync(iocb, 0);
1366 return ret;
1367}
1368
Badari Pulavartyeed4e512006-09-30 23:28:49 -07001369static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb)
1370{
1371 ssize_t ret;
1372
1373 ret = rw_copy_check_uvector(type, (struct iovec __user *)kiocb->ki_buf,
1374 kiocb->ki_nbytes, 1,
1375 &kiocb->ki_inline_vec, &kiocb->ki_iovec);
1376 if (ret < 0)
1377 goto out;
1378
1379 kiocb->ki_nr_segs = kiocb->ki_nbytes;
1380 kiocb->ki_cur_seg = 0;
1381 /* ki_nbytes/left now reflect bytes instead of segs */
1382 kiocb->ki_nbytes = ret;
1383 kiocb->ki_left = ret;
1384
1385 ret = 0;
1386out:
1387 return ret;
1388}
1389
1390static ssize_t aio_setup_single_vector(struct kiocb *kiocb)
1391{
1392 kiocb->ki_iovec = &kiocb->ki_inline_vec;
1393 kiocb->ki_iovec->iov_base = kiocb->ki_buf;
1394 kiocb->ki_iovec->iov_len = kiocb->ki_left;
1395 kiocb->ki_nr_segs = 1;
1396 kiocb->ki_cur_seg = 0;
Badari Pulavartyeed4e512006-09-30 23:28:49 -07001397 return 0;
1398}
1399
Linus Torvalds1da177e2005-04-16 15:20:36 -07001400/*
1401 * aio_setup_iocb:
1402 * Performs the initial checks and aio retry method
1403 * setup for the kiocb at the time of io submission.
1404 */
Adrian Bunk25ee7e32005-04-25 08:18:14 -07001405static ssize_t aio_setup_iocb(struct kiocb *kiocb)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001406{
1407 struct file *file = kiocb->ki_filp;
1408 ssize_t ret = 0;
1409
1410 switch (kiocb->ki_opcode) {
1411 case IOCB_CMD_PREAD:
1412 ret = -EBADF;
1413 if (unlikely(!(file->f_mode & FMODE_READ)))
1414 break;
1415 ret = -EFAULT;
1416 if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf,
1417 kiocb->ki_left)))
1418 break;
Kostik Belousov8766ce42005-10-23 12:57:13 -07001419 ret = security_file_permission(file, MAY_READ);
1420 if (unlikely(ret))
1421 break;
Badari Pulavartyeed4e512006-09-30 23:28:49 -07001422 ret = aio_setup_single_vector(kiocb);
1423 if (ret)
1424 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425 ret = -EINVAL;
1426 if (file->f_op->aio_read)
Badari Pulavartyeed4e512006-09-30 23:28:49 -07001427 kiocb->ki_retry = aio_rw_vect_retry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428 break;
1429 case IOCB_CMD_PWRITE:
1430 ret = -EBADF;
1431 if (unlikely(!(file->f_mode & FMODE_WRITE)))
1432 break;
1433 ret = -EFAULT;
1434 if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf,
1435 kiocb->ki_left)))
1436 break;
Kostik Belousov8766ce42005-10-23 12:57:13 -07001437 ret = security_file_permission(file, MAY_WRITE);
1438 if (unlikely(ret))
1439 break;
Badari Pulavartyeed4e512006-09-30 23:28:49 -07001440 ret = aio_setup_single_vector(kiocb);
1441 if (ret)
1442 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443 ret = -EINVAL;
1444 if (file->f_op->aio_write)
Badari Pulavartyeed4e512006-09-30 23:28:49 -07001445 kiocb->ki_retry = aio_rw_vect_retry;
1446 break;
1447 case IOCB_CMD_PREADV:
1448 ret = -EBADF;
1449 if (unlikely(!(file->f_mode & FMODE_READ)))
1450 break;
1451 ret = security_file_permission(file, MAY_READ);
1452 if (unlikely(ret))
1453 break;
1454 ret = aio_setup_vectored_rw(READ, kiocb);
1455 if (ret)
1456 break;
1457 ret = -EINVAL;
1458 if (file->f_op->aio_read)
1459 kiocb->ki_retry = aio_rw_vect_retry;
1460 break;
1461 case IOCB_CMD_PWRITEV:
1462 ret = -EBADF;
1463 if (unlikely(!(file->f_mode & FMODE_WRITE)))
1464 break;
1465 ret = security_file_permission(file, MAY_WRITE);
1466 if (unlikely(ret))
1467 break;
1468 ret = aio_setup_vectored_rw(WRITE, kiocb);
1469 if (ret)
1470 break;
1471 ret = -EINVAL;
1472 if (file->f_op->aio_write)
1473 kiocb->ki_retry = aio_rw_vect_retry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001474 break;
1475 case IOCB_CMD_FDSYNC:
1476 ret = -EINVAL;
1477 if (file->f_op->aio_fsync)
1478 kiocb->ki_retry = aio_fdsync;
1479 break;
1480 case IOCB_CMD_FSYNC:
1481 ret = -EINVAL;
1482 if (file->f_op->aio_fsync)
1483 kiocb->ki_retry = aio_fsync;
1484 break;
1485 default:
1486 dprintk("EINVAL: io_submit: no operation provided\n");
1487 ret = -EINVAL;
1488 }
1489
1490 if (!kiocb->ki_retry)
1491 return ret;
1492
1493 return 0;
1494}
1495
1496/*
1497 * aio_wake_function:
1498 * wait queue callback function for aio notification,
1499 * Simply triggers a retry of the operation via kick_iocb.
1500 *
1501 * This callback is specified in the wait queue entry in
1502 * a kiocb (current->io_wait points to this wait queue
1503 * entry when an aio operation executes; it is used
1504 * instead of a synchronous wait when an i/o blocking
1505 * condition is encountered during aio).
1506 *
1507 * Note:
1508 * This routine is executed with the wait queue lock held.
1509 * Since kick_iocb acquires iocb->ctx->ctx_lock, it nests
1510 * the ioctx lock inside the wait queue lock. This is safe
1511 * because this callback isn't used for wait queues which
1512 * are nested inside ioctx lock (i.e. ctx->wait)
1513 */
Adrian Bunk25ee7e32005-04-25 08:18:14 -07001514static int aio_wake_function(wait_queue_t *wait, unsigned mode,
1515 int sync, void *key)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001516{
1517 struct kiocb *iocb = container_of(wait, struct kiocb, ki_wait);
1518
1519 list_del_init(&wait->task_list);
1520 kick_iocb(iocb);
1521 return 1;
1522}
1523
1524int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1525 struct iocb *iocb)
1526{
1527 struct kiocb *req;
1528 struct file *file;
1529 ssize_t ret;
1530
1531 /* enforce forwards compatibility on users */
1532 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2 ||
1533 iocb->aio_reserved3)) {
1534 pr_debug("EINVAL: io_submit: reserve field set\n");
1535 return -EINVAL;
1536 }
1537
1538 /* prevent overflows */
1539 if (unlikely(
1540 (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
1541 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
1542 ((ssize_t)iocb->aio_nbytes < 0)
1543 )) {
1544 pr_debug("EINVAL: io_submit: overflow check\n");
1545 return -EINVAL;
1546 }
1547
1548 file = fget(iocb->aio_fildes);
1549 if (unlikely(!file))
1550 return -EBADF;
1551
1552 req = aio_get_req(ctx); /* returns with 2 references to req */
1553 if (unlikely(!req)) {
1554 fput(file);
1555 return -EAGAIN;
1556 }
1557
1558 req->ki_filp = file;
Ken Chen212079c2005-05-01 08:59:15 -07001559 ret = put_user(req->ki_key, &user_iocb->aio_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001560 if (unlikely(ret)) {
1561 dprintk("EFAULT: aio_key\n");
1562 goto out_put_req;
1563 }
1564
1565 req->ki_obj.user = user_iocb;
1566 req->ki_user_data = iocb->aio_data;
1567 req->ki_pos = iocb->aio_offset;
1568
1569 req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf;
1570 req->ki_left = req->ki_nbytes = iocb->aio_nbytes;
1571 req->ki_opcode = iocb->aio_lio_opcode;
1572 init_waitqueue_func_entry(&req->ki_wait, aio_wake_function);
1573 INIT_LIST_HEAD(&req->ki_wait.task_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574
1575 ret = aio_setup_iocb(req);
1576
1577 if (ret)
1578 goto out_put_req;
1579
1580 spin_lock_irq(&ctx->ctx_lock);
Benjamin LaHaiseac0b1bc2005-09-09 13:02:09 -07001581 aio_run_iocb(req);
Benjamin LaHaiseac0b1bc2005-09-09 13:02:09 -07001582 if (!list_empty(&ctx->run_list)) {
Ken Chen954d3e92005-05-01 08:59:16 -07001583 /* drain the run list */
1584 while (__aio_run_iocbs(ctx))
1585 ;
1586 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587 spin_unlock_irq(&ctx->ctx_lock);
1588 aio_put_req(req); /* drop extra ref to req */
1589 return 0;
1590
1591out_put_req:
1592 aio_put_req(req); /* drop extra ref to req */
1593 aio_put_req(req); /* drop i/o ref to req */
1594 return ret;
1595}
1596
1597/* sys_io_submit:
1598 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1599 * the number of iocbs queued. May return -EINVAL if the aio_context
1600 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1601 * *iocbpp[0] is not properly initialized, if the operation specified
1602 * is invalid for the file descriptor in the iocb. May fail with
1603 * -EFAULT if any of the data structures point to invalid data. May
1604 * fail with -EBADF if the file descriptor specified in the first
1605 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1606 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1607 * fail with -ENOSYS if not implemented.
1608 */
1609asmlinkage long sys_io_submit(aio_context_t ctx_id, long nr,
1610 struct iocb __user * __user *iocbpp)
1611{
1612 struct kioctx *ctx;
1613 long ret = 0;
1614 int i;
1615
1616 if (unlikely(nr < 0))
1617 return -EINVAL;
1618
1619 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1620 return -EFAULT;
1621
1622 ctx = lookup_ioctx(ctx_id);
1623 if (unlikely(!ctx)) {
1624 pr_debug("EINVAL: io_submit: invalid context id\n");
1625 return -EINVAL;
1626 }
1627
1628 /*
1629 * AKPM: should this return a partial result if some of the IOs were
1630 * successfully submitted?
1631 */
1632 for (i=0; i<nr; i++) {
1633 struct iocb __user *user_iocb;
1634 struct iocb tmp;
1635
1636 if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1637 ret = -EFAULT;
1638 break;
1639 }
1640
1641 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1642 ret = -EFAULT;
1643 break;
1644 }
1645
1646 ret = io_submit_one(ctx, user_iocb, &tmp);
1647 if (ret)
1648 break;
1649 }
1650
1651 put_ioctx(ctx);
1652 return i ? i : ret;
1653}
1654
1655/* lookup_kiocb
1656 * Finds a given iocb for cancellation.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001657 */
Adrian Bunk25ee7e32005-04-25 08:18:14 -07001658static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
1659 u32 key)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660{
1661 struct list_head *pos;
Zach Brownd00689a2005-11-13 16:07:34 -08001662
1663 assert_spin_locked(&ctx->ctx_lock);
1664
Linus Torvalds1da177e2005-04-16 15:20:36 -07001665 /* TODO: use a hash or array, this sucks. */
1666 list_for_each(pos, &ctx->active_reqs) {
1667 struct kiocb *kiocb = list_kiocb(pos);
1668 if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key)
1669 return kiocb;
1670 }
1671 return NULL;
1672}
1673
1674/* sys_io_cancel:
1675 * Attempts to cancel an iocb previously passed to io_submit. If
1676 * the operation is successfully cancelled, the resulting event is
1677 * copied into the memory pointed to by result without being placed
1678 * into the completion queue and 0 is returned. May fail with
1679 * -EFAULT if any of the data structures pointed to are invalid.
1680 * May fail with -EINVAL if aio_context specified by ctx_id is
1681 * invalid. May fail with -EAGAIN if the iocb specified was not
1682 * cancelled. Will fail with -ENOSYS if not implemented.
1683 */
1684asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb,
1685 struct io_event __user *result)
1686{
1687 int (*cancel)(struct kiocb *iocb, struct io_event *res);
1688 struct kioctx *ctx;
1689 struct kiocb *kiocb;
1690 u32 key;
1691 int ret;
1692
1693 ret = get_user(key, &iocb->aio_key);
1694 if (unlikely(ret))
1695 return -EFAULT;
1696
1697 ctx = lookup_ioctx(ctx_id);
1698 if (unlikely(!ctx))
1699 return -EINVAL;
1700
1701 spin_lock_irq(&ctx->ctx_lock);
1702 ret = -EAGAIN;
1703 kiocb = lookup_kiocb(ctx, iocb, key);
1704 if (kiocb && kiocb->ki_cancel) {
1705 cancel = kiocb->ki_cancel;
1706 kiocb->ki_users ++;
1707 kiocbSetCancelled(kiocb);
1708 } else
1709 cancel = NULL;
1710 spin_unlock_irq(&ctx->ctx_lock);
1711
1712 if (NULL != cancel) {
1713 struct io_event tmp;
1714 pr_debug("calling cancel\n");
1715 memset(&tmp, 0, sizeof(tmp));
1716 tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user;
1717 tmp.data = kiocb->ki_user_data;
1718 ret = cancel(kiocb, &tmp);
1719 if (!ret) {
1720 /* Cancellation succeeded -- copy the result
1721 * into the user's buffer.
1722 */
1723 if (copy_to_user(result, &tmp, sizeof(tmp)))
1724 ret = -EFAULT;
1725 }
1726 } else
Wendy Cheng8f582022005-09-09 13:02:08 -07001727 ret = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001728
1729 put_ioctx(ctx);
1730
1731 return ret;
1732}
1733
1734/* io_getevents:
1735 * Attempts to read at least min_nr events and up to nr events from
1736 * the completion queue for the aio_context specified by ctx_id. May
1737 * fail with -EINVAL if ctx_id is invalid, if min_nr is out of range,
1738 * if nr is out of range, if when is out of range. May fail with
1739 * -EFAULT if any of the memory specified to is invalid. May return
1740 * 0 or < min_nr if no events are available and the timeout specified
1741 * by when has elapsed, where when == NULL specifies an infinite
1742 * timeout. Note that the timeout pointed to by when is relative and
1743 * will be updated if not NULL and the operation blocks. Will fail
1744 * with -ENOSYS if not implemented.
1745 */
1746asmlinkage long sys_io_getevents(aio_context_t ctx_id,
1747 long min_nr,
1748 long nr,
1749 struct io_event __user *events,
1750 struct timespec __user *timeout)
1751{
1752 struct kioctx *ioctx = lookup_ioctx(ctx_id);
1753 long ret = -EINVAL;
1754
1755 if (likely(ioctx)) {
1756 if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0))
1757 ret = read_events(ioctx, min_nr, nr, events, timeout);
1758 put_ioctx(ioctx);
1759 }
1760
1761 return ret;
1762}
1763
1764__initcall(aio_setup);
1765
1766EXPORT_SYMBOL(aio_complete);
1767EXPORT_SYMBOL(aio_put_req);
1768EXPORT_SYMBOL(wait_on_sync_kiocb);