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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/mempool.h> |
38 | #include <linux/hash.h> |
39 | |
40 | #include <asm/kmap_types.h> |
41 | #include <asm/uaccess.h> |
42 | |
43 | #if DEBUG > 1 |
44 | #define dprintk printk |
45 | #else |
46 | #define dprintk(x...) do { ; } while (0) |
47 | #endif |
48 | |
49 | /*------ sysctl variables----*/ |
50 | static DEFINE_SPINLOCK(aio_nr_lock); |
51 | unsigned long aio_nr; /* current system wide number of aio requests */ |
52 | unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */ |
53 | /*----end sysctl variables---*/ |
54 | |
55 | static struct kmem_cache *kiocb_cachep; |
56 | static struct kmem_cache *kioctx_cachep; |
57 | |
58 | static struct workqueue_struct *aio_wq; |
59 | |
60 | /* Used for rare fput completion. */ |
61 | static void aio_fput_routine(struct work_struct *); |
62 | static DECLARE_WORK(fput_work, aio_fput_routine); |
63 | |
64 | static DEFINE_SPINLOCK(fput_lock); |
65 | static LIST_HEAD(fput_head); |
66 | |
67 | #define AIO_BATCH_HASH_BITS 3 /* allocated on-stack, so don't go crazy */ |
68 | #define AIO_BATCH_HASH_SIZE (1 << AIO_BATCH_HASH_BITS) |
69 | struct aio_batch_entry { |
70 | struct hlist_node list; |
71 | struct address_space *mapping; |
72 | }; |
73 | mempool_t *abe_pool; |
74 | |
75 | static void aio_kick_handler(struct work_struct *); |
76 | static void aio_queue_work(struct kioctx *); |
77 | |
78 | /* aio_setup |
79 | * Creates the slab caches used by the aio routines, panic on |
80 | * failure as this is done early during the boot sequence. |
81 | */ |
82 | static int __init aio_setup(void) |
83 | { |
84 | kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC); |
85 | kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC); |
86 | |
87 | aio_wq = create_workqueue("aio"); |
88 | abe_pool = mempool_create_kmalloc_pool(1, sizeof(struct aio_batch_entry)); |
89 | BUG_ON(!abe_pool); |
90 | |
91 | pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page)); |
92 | |
93 | return 0; |
94 | } |
95 | __initcall(aio_setup); |
96 | |
97 | static void aio_free_ring(struct kioctx *ctx) |
98 | { |
99 | struct aio_ring_info *info = &ctx->ring_info; |
100 | long i; |
101 | |
102 | for (i=0; i<info->nr_pages; i++) |
103 | put_page(info->ring_pages[i]); |
104 | |
105 | if (info->mmap_size) { |
106 | down_write(&ctx->mm->mmap_sem); |
107 | do_munmap(ctx->mm, info->mmap_base, info->mmap_size); |
108 | up_write(&ctx->mm->mmap_sem); |
109 | } |
110 | |
111 | if (info->ring_pages && info->ring_pages != info->internal_pages) |
112 | kfree(info->ring_pages); |
113 | info->ring_pages = NULL; |
114 | info->nr = 0; |
115 | } |
116 | |
117 | static int aio_setup_ring(struct kioctx *ctx) |
118 | { |
119 | struct aio_ring *ring; |
120 | struct aio_ring_info *info = &ctx->ring_info; |
121 | unsigned nr_events = ctx->max_reqs; |
122 | unsigned long size; |
123 | int nr_pages; |
124 | |
125 | /* Compensate for the ring buffer's head/tail overlap entry */ |
126 | nr_events += 2; /* 1 is required, 2 for good luck */ |
127 | |
128 | size = sizeof(struct aio_ring); |
129 | size += sizeof(struct io_event) * nr_events; |
130 | nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT; |
131 | |
132 | if (nr_pages < 0) |
133 | return -EINVAL; |
134 | |
135 | nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event); |
136 | |
137 | info->nr = 0; |
138 | info->ring_pages = info->internal_pages; |
139 | if (nr_pages > AIO_RING_PAGES) { |
140 | info->ring_pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL); |
141 | if (!info->ring_pages) |
142 | return -ENOMEM; |
143 | } |
144 | |
145 | info->mmap_size = nr_pages * PAGE_SIZE; |
146 | dprintk("attempting mmap of %lu bytes\n", info->mmap_size); |
147 | down_write(&ctx->mm->mmap_sem); |
148 | info->mmap_base = do_mmap(NULL, 0, info->mmap_size, |
149 | PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, |
150 | 0); |
151 | if (IS_ERR((void *)info->mmap_base)) { |
152 | up_write(&ctx->mm->mmap_sem); |
153 | info->mmap_size = 0; |
154 | aio_free_ring(ctx); |
155 | return -EAGAIN; |
156 | } |
157 | |
158 | dprintk("mmap address: 0x%08lx\n", info->mmap_base); |
159 | info->nr_pages = get_user_pages(current, ctx->mm, |
160 | info->mmap_base, nr_pages, |
161 | 1, 0, info->ring_pages, NULL); |
162 | up_write(&ctx->mm->mmap_sem); |
163 | |
164 | if (unlikely(info->nr_pages != nr_pages)) { |
165 | aio_free_ring(ctx); |
166 | return -EAGAIN; |
167 | } |
168 | |
169 | ctx->user_id = info->mmap_base; |
170 | |
171 | info->nr = nr_events; /* trusted copy */ |
172 | |
173 | ring = kmap_atomic(info->ring_pages[0], KM_USER0); |
174 | ring->nr = nr_events; /* user copy */ |
175 | ring->id = ctx->user_id; |
176 | ring->head = ring->tail = 0; |
177 | ring->magic = AIO_RING_MAGIC; |
178 | ring->compat_features = AIO_RING_COMPAT_FEATURES; |
179 | ring->incompat_features = AIO_RING_INCOMPAT_FEATURES; |
180 | ring->header_length = sizeof(struct aio_ring); |
181 | kunmap_atomic(ring, KM_USER0); |
182 | |
183 | return 0; |
184 | } |
185 | |
186 | |
187 | /* aio_ring_event: returns a pointer to the event at the given index from |
188 | * kmap_atomic(, km). Release the pointer with put_aio_ring_event(); |
189 | */ |
190 | #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event)) |
191 | #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event)) |
192 | #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE) |
193 | |
194 | #define aio_ring_event(info, nr, km) ({ \ |
195 | unsigned pos = (nr) + AIO_EVENTS_OFFSET; \ |
196 | struct io_event *__event; \ |
197 | __event = kmap_atomic( \ |
198 | (info)->ring_pages[pos / AIO_EVENTS_PER_PAGE], km); \ |
199 | __event += pos % AIO_EVENTS_PER_PAGE; \ |
200 | __event; \ |
201 | }) |
202 | |
203 | #define put_aio_ring_event(event, km) do { \ |
204 | struct io_event *__event = (event); \ |
205 | (void)__event; \ |
206 | kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK), km); \ |
207 | } while(0) |
208 | |
209 | static void ctx_rcu_free(struct rcu_head *head) |
210 | { |
211 | struct kioctx *ctx = container_of(head, struct kioctx, rcu_head); |
212 | unsigned nr_events = ctx->max_reqs; |
213 | |
214 | kmem_cache_free(kioctx_cachep, ctx); |
215 | |
216 | if (nr_events) { |
217 | spin_lock(&aio_nr_lock); |
218 | BUG_ON(aio_nr - nr_events > aio_nr); |
219 | aio_nr -= nr_events; |
220 | spin_unlock(&aio_nr_lock); |
221 | } |
222 | } |
223 | |
224 | /* __put_ioctx |
225 | * Called when the last user of an aio context has gone away, |
226 | * and the struct needs to be freed. |
227 | */ |
228 | static void __put_ioctx(struct kioctx *ctx) |
229 | { |
230 | BUG_ON(ctx->reqs_active); |
231 | |
232 | cancel_delayed_work(&ctx->wq); |
233 | cancel_work_sync(&ctx->wq.work); |
234 | aio_free_ring(ctx); |
235 | mmdrop(ctx->mm); |
236 | ctx->mm = NULL; |
237 | pr_debug("__put_ioctx: freeing %p\n", ctx); |
238 | call_rcu(&ctx->rcu_head, ctx_rcu_free); |
239 | } |
240 | |
241 | #define get_ioctx(kioctx) do { \ |
242 | BUG_ON(atomic_read(&(kioctx)->users) <= 0); \ |
243 | atomic_inc(&(kioctx)->users); \ |
244 | } while (0) |
245 | #define put_ioctx(kioctx) do { \ |
246 | BUG_ON(atomic_read(&(kioctx)->users) <= 0); \ |
247 | if (unlikely(atomic_dec_and_test(&(kioctx)->users))) \ |
248 | __put_ioctx(kioctx); \ |
249 | } while (0) |
250 | |
251 | /* ioctx_alloc |
252 | * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed. |
253 | */ |
254 | static struct kioctx *ioctx_alloc(unsigned nr_events) |
255 | { |
256 | struct mm_struct *mm; |
257 | struct kioctx *ctx; |
258 | int did_sync = 0; |
259 | |
260 | /* Prevent overflows */ |
261 | if ((nr_events > (0x10000000U / sizeof(struct io_event))) || |
262 | (nr_events > (0x10000000U / sizeof(struct kiocb)))) { |
263 | pr_debug("ENOMEM: nr_events too high\n"); |
264 | return ERR_PTR(-EINVAL); |
265 | } |
266 | |
267 | if ((unsigned long)nr_events > aio_max_nr) |
268 | return ERR_PTR(-EAGAIN); |
269 | |
270 | ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL); |
271 | if (!ctx) |
272 | return ERR_PTR(-ENOMEM); |
273 | |
274 | ctx->max_reqs = nr_events; |
275 | mm = ctx->mm = current->mm; |
276 | atomic_inc(&mm->mm_count); |
277 | |
278 | atomic_set(&ctx->users, 1); |
279 | spin_lock_init(&ctx->ctx_lock); |
280 | spin_lock_init(&ctx->ring_info.ring_lock); |
281 | init_waitqueue_head(&ctx->wait); |
282 | |
283 | INIT_LIST_HEAD(&ctx->active_reqs); |
284 | INIT_LIST_HEAD(&ctx->run_list); |
285 | INIT_DELAYED_WORK(&ctx->wq, aio_kick_handler); |
286 | |
287 | if (aio_setup_ring(ctx) < 0) |
288 | goto out_freectx; |
289 | |
290 | /* limit the number of system wide aios */ |
291 | do { |
292 | spin_lock_bh(&aio_nr_lock); |
293 | if (aio_nr + nr_events > aio_max_nr || |
294 | aio_nr + nr_events < aio_nr) |
295 | ctx->max_reqs = 0; |
296 | else |
297 | aio_nr += ctx->max_reqs; |
298 | spin_unlock_bh(&aio_nr_lock); |
299 | if (ctx->max_reqs || did_sync) |
300 | break; |
301 | |
302 | /* wait for rcu callbacks to have completed before giving up */ |
303 | synchronize_rcu(); |
304 | did_sync = 1; |
305 | ctx->max_reqs = nr_events; |
306 | } while (1); |
307 | |
308 | if (ctx->max_reqs == 0) |
309 | goto out_cleanup; |
310 | |
311 | /* now link into global list. */ |
312 | spin_lock(&mm->ioctx_lock); |
313 | hlist_add_head_rcu(&ctx->list, &mm->ioctx_list); |
314 | spin_unlock(&mm->ioctx_lock); |
315 | |
316 | dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n", |
317 | ctx, ctx->user_id, current->mm, ctx->ring_info.nr); |
318 | return ctx; |
319 | |
320 | out_cleanup: |
321 | __put_ioctx(ctx); |
322 | return ERR_PTR(-EAGAIN); |
323 | |
324 | out_freectx: |
325 | mmdrop(mm); |
326 | kmem_cache_free(kioctx_cachep, ctx); |
327 | ctx = ERR_PTR(-ENOMEM); |
328 | |
329 | dprintk("aio: error allocating ioctx %p\n", ctx); |
330 | return ctx; |
331 | } |
332 | |
333 | /* aio_cancel_all |
334 | * Cancels all outstanding aio requests on an aio context. Used |
335 | * when the processes owning a context have all exited to encourage |
336 | * the rapid destruction of the kioctx. |
337 | */ |
338 | static void aio_cancel_all(struct kioctx *ctx) |
339 | { |
340 | int (*cancel)(struct kiocb *, struct io_event *); |
341 | struct io_event res; |
342 | spin_lock_irq(&ctx->ctx_lock); |
343 | ctx->dead = 1; |
344 | while (!list_empty(&ctx->active_reqs)) { |
345 | struct list_head *pos = ctx->active_reqs.next; |
346 | struct kiocb *iocb = list_kiocb(pos); |
347 | list_del_init(&iocb->ki_list); |
348 | cancel = iocb->ki_cancel; |
349 | kiocbSetCancelled(iocb); |
350 | if (cancel) { |
351 | iocb->ki_users++; |
352 | spin_unlock_irq(&ctx->ctx_lock); |
353 | cancel(iocb, &res); |
354 | spin_lock_irq(&ctx->ctx_lock); |
355 | } |
356 | } |
357 | spin_unlock_irq(&ctx->ctx_lock); |
358 | } |
359 | |
360 | static void wait_for_all_aios(struct kioctx *ctx) |
361 | { |
362 | struct task_struct *tsk = current; |
363 | DECLARE_WAITQUEUE(wait, tsk); |
364 | |
365 | spin_lock_irq(&ctx->ctx_lock); |
366 | if (!ctx->reqs_active) |
367 | goto out; |
368 | |
369 | add_wait_queue(&ctx->wait, &wait); |
370 | set_task_state(tsk, TASK_UNINTERRUPTIBLE); |
371 | while (ctx->reqs_active) { |
372 | spin_unlock_irq(&ctx->ctx_lock); |
373 | io_schedule(); |
374 | set_task_state(tsk, TASK_UNINTERRUPTIBLE); |
375 | spin_lock_irq(&ctx->ctx_lock); |
376 | } |
377 | __set_task_state(tsk, TASK_RUNNING); |
378 | remove_wait_queue(&ctx->wait, &wait); |
379 | |
380 | out: |
381 | spin_unlock_irq(&ctx->ctx_lock); |
382 | } |
383 | |
384 | /* wait_on_sync_kiocb: |
385 | * Waits on the given sync kiocb to complete. |
386 | */ |
387 | ssize_t wait_on_sync_kiocb(struct kiocb *iocb) |
388 | { |
389 | while (iocb->ki_users) { |
390 | set_current_state(TASK_UNINTERRUPTIBLE); |
391 | if (!iocb->ki_users) |
392 | break; |
393 | io_schedule(); |
394 | } |
395 | __set_current_state(TASK_RUNNING); |
396 | return iocb->ki_user_data; |
397 | } |
398 | EXPORT_SYMBOL(wait_on_sync_kiocb); |
399 | |
400 | /* exit_aio: called when the last user of mm goes away. At this point, |
401 | * there is no way for any new requests to be submited or any of the |
402 | * io_* syscalls to be called on the context. However, there may be |
403 | * outstanding requests which hold references to the context; as they |
404 | * go away, they will call put_ioctx and release any pinned memory |
405 | * associated with the request (held via struct page * references). |
406 | */ |
407 | void exit_aio(struct mm_struct *mm) |
408 | { |
409 | struct kioctx *ctx; |
410 | |
411 | while (!hlist_empty(&mm->ioctx_list)) { |
412 | ctx = hlist_entry(mm->ioctx_list.first, struct kioctx, list); |
413 | hlist_del_rcu(&ctx->list); |
414 | |
415 | aio_cancel_all(ctx); |
416 | |
417 | wait_for_all_aios(ctx); |
418 | /* |
419 | * Ensure we don't leave the ctx on the aio_wq |
420 | */ |
421 | cancel_work_sync(&ctx->wq.work); |
422 | |
423 | if (1 != atomic_read(&ctx->users)) |
424 | printk(KERN_DEBUG |
425 | "exit_aio:ioctx still alive: %d %d %d\n", |
426 | atomic_read(&ctx->users), ctx->dead, |
427 | ctx->reqs_active); |
428 | put_ioctx(ctx); |
429 | } |
430 | } |
431 | |
432 | /* aio_get_req |
433 | * Allocate a slot for an aio request. Increments the users count |
434 | * of the kioctx so that the kioctx stays around until all requests are |
435 | * complete. Returns NULL if no requests are free. |
436 | * |
437 | * Returns with kiocb->users set to 2. The io submit code path holds |
438 | * an extra reference while submitting the i/o. |
439 | * This prevents races between the aio code path referencing the |
440 | * req (after submitting it) and aio_complete() freeing the req. |
441 | */ |
442 | static struct kiocb *__aio_get_req(struct kioctx *ctx) |
443 | { |
444 | struct kiocb *req = NULL; |
445 | struct aio_ring *ring; |
446 | int okay = 0; |
447 | |
448 | req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL); |
449 | if (unlikely(!req)) |
450 | return NULL; |
451 | |
452 | req->ki_flags = 0; |
453 | req->ki_users = 2; |
454 | req->ki_key = 0; |
455 | req->ki_ctx = ctx; |
456 | req->ki_cancel = NULL; |
457 | req->ki_retry = NULL; |
458 | req->ki_dtor = NULL; |
459 | req->private = NULL; |
460 | req->ki_iovec = NULL; |
461 | INIT_LIST_HEAD(&req->ki_run_list); |
462 | req->ki_eventfd = NULL; |
463 | |
464 | /* Check if the completion queue has enough free space to |
465 | * accept an event from this io. |
466 | */ |
467 | spin_lock_irq(&ctx->ctx_lock); |
468 | ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0); |
469 | if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) { |
470 | list_add(&req->ki_list, &ctx->active_reqs); |
471 | ctx->reqs_active++; |
472 | okay = 1; |
473 | } |
474 | kunmap_atomic(ring, KM_USER0); |
475 | spin_unlock_irq(&ctx->ctx_lock); |
476 | |
477 | if (!okay) { |
478 | kmem_cache_free(kiocb_cachep, req); |
479 | req = NULL; |
480 | } |
481 | |
482 | return req; |
483 | } |
484 | |
485 | static inline struct kiocb *aio_get_req(struct kioctx *ctx) |
486 | { |
487 | struct kiocb *req; |
488 | /* Handle a potential starvation case -- should be exceedingly rare as |
489 | * requests will be stuck on fput_head only if the aio_fput_routine is |
490 | * delayed and the requests were the last user of the struct file. |
491 | */ |
492 | req = __aio_get_req(ctx); |
493 | if (unlikely(NULL == req)) { |
494 | aio_fput_routine(NULL); |
495 | req = __aio_get_req(ctx); |
496 | } |
497 | return req; |
498 | } |
499 | |
500 | static inline void really_put_req(struct kioctx *ctx, struct kiocb *req) |
501 | { |
502 | assert_spin_locked(&ctx->ctx_lock); |
503 | |
504 | if (req->ki_eventfd != NULL) |
505 | eventfd_ctx_put(req->ki_eventfd); |
506 | if (req->ki_dtor) |
507 | req->ki_dtor(req); |
508 | if (req->ki_iovec != &req->ki_inline_vec) |
509 | kfree(req->ki_iovec); |
510 | kmem_cache_free(kiocb_cachep, req); |
511 | ctx->reqs_active--; |
512 | |
513 | if (unlikely(!ctx->reqs_active && ctx->dead)) |
514 | wake_up(&ctx->wait); |
515 | } |
516 | |
517 | static void aio_fput_routine(struct work_struct *data) |
518 | { |
519 | spin_lock_irq(&fput_lock); |
520 | while (likely(!list_empty(&fput_head))) { |
521 | struct kiocb *req = list_kiocb(fput_head.next); |
522 | struct kioctx *ctx = req->ki_ctx; |
523 | |
524 | list_del(&req->ki_list); |
525 | spin_unlock_irq(&fput_lock); |
526 | |
527 | /* Complete the fput(s) */ |
528 | if (req->ki_filp != NULL) |
529 | __fput(req->ki_filp); |
530 | |
531 | /* Link the iocb into the context's free list */ |
532 | spin_lock_irq(&ctx->ctx_lock); |
533 | really_put_req(ctx, req); |
534 | spin_unlock_irq(&ctx->ctx_lock); |
535 | |
536 | put_ioctx(ctx); |
537 | spin_lock_irq(&fput_lock); |
538 | } |
539 | spin_unlock_irq(&fput_lock); |
540 | } |
541 | |
542 | /* __aio_put_req |
543 | * Returns true if this put was the last user of the request. |
544 | */ |
545 | static int __aio_put_req(struct kioctx *ctx, struct kiocb *req) |
546 | { |
547 | dprintk(KERN_DEBUG "aio_put(%p): f_count=%ld\n", |
548 | req, atomic_long_read(&req->ki_filp->f_count)); |
549 | |
550 | assert_spin_locked(&ctx->ctx_lock); |
551 | |
552 | req->ki_users--; |
553 | BUG_ON(req->ki_users < 0); |
554 | if (likely(req->ki_users)) |
555 | return 0; |
556 | list_del(&req->ki_list); /* remove from active_reqs */ |
557 | req->ki_cancel = NULL; |
558 | req->ki_retry = NULL; |
559 | |
560 | /* |
561 | * Try to optimize the aio and eventfd file* puts, by avoiding to |
562 | * schedule work in case it is not __fput() time. In normal cases, |
563 | * we would not be holding the last reference to the file*, so |
564 | * this function will be executed w/out any aio kthread wakeup. |
565 | */ |
566 | if (unlikely(atomic_long_dec_and_test(&req->ki_filp->f_count))) { |
567 | get_ioctx(ctx); |
568 | spin_lock(&fput_lock); |
569 | list_add(&req->ki_list, &fput_head); |
570 | spin_unlock(&fput_lock); |
571 | queue_work(aio_wq, &fput_work); |
572 | } else { |
573 | req->ki_filp = NULL; |
574 | really_put_req(ctx, req); |
575 | } |
576 | return 1; |
577 | } |
578 | |
579 | /* aio_put_req |
580 | * Returns true if this put was the last user of the kiocb, |
581 | * false if the request is still in use. |
582 | */ |
583 | int aio_put_req(struct kiocb *req) |
584 | { |
585 | struct kioctx *ctx = req->ki_ctx; |
586 | int ret; |
587 | spin_lock_irq(&ctx->ctx_lock); |
588 | ret = __aio_put_req(ctx, req); |
589 | spin_unlock_irq(&ctx->ctx_lock); |
590 | return ret; |
591 | } |
592 | EXPORT_SYMBOL(aio_put_req); |
593 | |
594 | static struct kioctx *lookup_ioctx(unsigned long ctx_id) |
595 | { |
596 | struct mm_struct *mm = current->mm; |
597 | struct kioctx *ctx, *ret = NULL; |
598 | struct hlist_node *n; |
599 | |
600 | rcu_read_lock(); |
601 | |
602 | hlist_for_each_entry_rcu(ctx, n, &mm->ioctx_list, list) { |
603 | if (ctx->user_id == ctx_id && !ctx->dead) { |
604 | get_ioctx(ctx); |
605 | ret = ctx; |
606 | break; |
607 | } |
608 | } |
609 | |
610 | rcu_read_unlock(); |
611 | return ret; |
612 | } |
613 | |
614 | /* |
615 | * Queue up a kiocb to be retried. Assumes that the kiocb |
616 | * has already been marked as kicked, and places it on |
617 | * the retry run list for the corresponding ioctx, if it |
618 | * isn't already queued. Returns 1 if it actually queued |
619 | * the kiocb (to tell the caller to activate the work |
620 | * queue to process it), or 0, if it found that it was |
621 | * already queued. |
622 | */ |
623 | static inline int __queue_kicked_iocb(struct kiocb *iocb) |
624 | { |
625 | struct kioctx *ctx = iocb->ki_ctx; |
626 | |
627 | assert_spin_locked(&ctx->ctx_lock); |
628 | |
629 | if (list_empty(&iocb->ki_run_list)) { |
630 | list_add_tail(&iocb->ki_run_list, |
631 | &ctx->run_list); |
632 | return 1; |
633 | } |
634 | return 0; |
635 | } |
636 | |
637 | /* aio_run_iocb |
638 | * This is the core aio execution routine. It is |
639 | * invoked both for initial i/o submission and |
640 | * subsequent retries via the aio_kick_handler. |
641 | * Expects to be invoked with iocb->ki_ctx->lock |
642 | * already held. The lock is released and reacquired |
643 | * as needed during processing. |
644 | * |
645 | * Calls the iocb retry method (already setup for the |
646 | * iocb on initial submission) for operation specific |
647 | * handling, but takes care of most of common retry |
648 | * execution details for a given iocb. The retry method |
649 | * needs to be non-blocking as far as possible, to avoid |
650 | * holding up other iocbs waiting to be serviced by the |
651 | * retry kernel thread. |
652 | * |
653 | * The trickier parts in this code have to do with |
654 | * ensuring that only one retry instance is in progress |
655 | * for a given iocb at any time. Providing that guarantee |
656 | * simplifies the coding of individual aio operations as |
657 | * it avoids various potential races. |
658 | */ |
659 | static ssize_t aio_run_iocb(struct kiocb *iocb) |
660 | { |
661 | struct kioctx *ctx = iocb->ki_ctx; |
662 | ssize_t (*retry)(struct kiocb *); |
663 | ssize_t ret; |
664 | |
665 | if (!(retry = iocb->ki_retry)) { |
666 | printk("aio_run_iocb: iocb->ki_retry = NULL\n"); |
667 | return 0; |
668 | } |
669 | |
670 | /* |
671 | * We don't want the next retry iteration for this |
672 | * operation to start until this one has returned and |
673 | * updated the iocb state. However, wait_queue functions |
674 | * can trigger a kick_iocb from interrupt context in the |
675 | * meantime, indicating that data is available for the next |
676 | * iteration. We want to remember that and enable the |
677 | * next retry iteration _after_ we are through with |
678 | * this one. |
679 | * |
680 | * So, in order to be able to register a "kick", but |
681 | * prevent it from being queued now, we clear the kick |
682 | * flag, but make the kick code *think* that the iocb is |
683 | * still on the run list until we are actually done. |
684 | * When we are done with this iteration, we check if |
685 | * the iocb was kicked in the meantime and if so, queue |
686 | * it up afresh. |
687 | */ |
688 | |
689 | kiocbClearKicked(iocb); |
690 | |
691 | /* |
692 | * This is so that aio_complete knows it doesn't need to |
693 | * pull the iocb off the run list (We can't just call |
694 | * INIT_LIST_HEAD because we don't want a kick_iocb to |
695 | * queue this on the run list yet) |
696 | */ |
697 | iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL; |
698 | spin_unlock_irq(&ctx->ctx_lock); |
699 | |
700 | /* Quit retrying if the i/o has been cancelled */ |
701 | if (kiocbIsCancelled(iocb)) { |
702 | ret = -EINTR; |
703 | aio_complete(iocb, ret, 0); |
704 | /* must not access the iocb after this */ |
705 | goto out; |
706 | } |
707 | |
708 | /* |
709 | * Now we are all set to call the retry method in async |
710 | * context. |
711 | */ |
712 | ret = retry(iocb); |
713 | |
714 | if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) |
715 | aio_complete(iocb, ret, 0); |
716 | out: |
717 | spin_lock_irq(&ctx->ctx_lock); |
718 | |
719 | if (-EIOCBRETRY == ret) { |
720 | /* |
721 | * OK, now that we are done with this iteration |
722 | * and know that there is more left to go, |
723 | * this is where we let go so that a subsequent |
724 | * "kick" can start the next iteration |
725 | */ |
726 | |
727 | /* will make __queue_kicked_iocb succeed from here on */ |
728 | INIT_LIST_HEAD(&iocb->ki_run_list); |
729 | /* we must queue the next iteration ourselves, if it |
730 | * has already been kicked */ |
731 | if (kiocbIsKicked(iocb)) { |
732 | __queue_kicked_iocb(iocb); |
733 | |
734 | /* |
735 | * __queue_kicked_iocb will always return 1 here, because |
736 | * iocb->ki_run_list is empty at this point so it should |
737 | * be safe to unconditionally queue the context into the |
738 | * work queue. |
739 | */ |
740 | aio_queue_work(ctx); |
741 | } |
742 | } |
743 | return ret; |
744 | } |
745 | |
746 | /* |
747 | * __aio_run_iocbs: |
748 | * Process all pending retries queued on the ioctx |
749 | * run list. |
750 | * Assumes it is operating within the aio issuer's mm |
751 | * context. |
752 | */ |
753 | static int __aio_run_iocbs(struct kioctx *ctx) |
754 | { |
755 | struct kiocb *iocb; |
756 | struct list_head run_list; |
757 | |
758 | assert_spin_locked(&ctx->ctx_lock); |
759 | |
760 | list_replace_init(&ctx->run_list, &run_list); |
761 | while (!list_empty(&run_list)) { |
762 | iocb = list_entry(run_list.next, struct kiocb, |
763 | ki_run_list); |
764 | list_del(&iocb->ki_run_list); |
765 | /* |
766 | * Hold an extra reference while retrying i/o. |
767 | */ |
768 | iocb->ki_users++; /* grab extra reference */ |
769 | aio_run_iocb(iocb); |
770 | __aio_put_req(ctx, iocb); |
771 | } |
772 | if (!list_empty(&ctx->run_list)) |
773 | return 1; |
774 | return 0; |
775 | } |
776 | |
777 | static void aio_queue_work(struct kioctx * ctx) |
778 | { |
779 | unsigned long timeout; |
780 | /* |
781 | * if someone is waiting, get the work started right |
782 | * away, otherwise, use a longer delay |
783 | */ |
784 | smp_mb(); |
785 | if (waitqueue_active(&ctx->wait)) |
786 | timeout = 1; |
787 | else |
788 | timeout = HZ/10; |
789 | queue_delayed_work(aio_wq, &ctx->wq, timeout); |
790 | } |
791 | |
792 | |
793 | /* |
794 | * aio_run_iocbs: |
795 | * Process all pending retries queued on the ioctx |
796 | * run list. |
797 | * Assumes it is operating within the aio issuer's mm |
798 | * context. |
799 | */ |
800 | static inline void aio_run_iocbs(struct kioctx *ctx) |
801 | { |
802 | int requeue; |
803 | |
804 | spin_lock_irq(&ctx->ctx_lock); |
805 | |
806 | requeue = __aio_run_iocbs(ctx); |
807 | spin_unlock_irq(&ctx->ctx_lock); |
808 | if (requeue) |
809 | aio_queue_work(ctx); |
810 | } |
811 | |
812 | /* |
813 | * just like aio_run_iocbs, but keeps running them until |
814 | * the list stays empty |
815 | */ |
816 | static inline void aio_run_all_iocbs(struct kioctx *ctx) |
817 | { |
818 | spin_lock_irq(&ctx->ctx_lock); |
819 | while (__aio_run_iocbs(ctx)) |
820 | ; |
821 | spin_unlock_irq(&ctx->ctx_lock); |
822 | } |
823 | |
824 | /* |
825 | * aio_kick_handler: |
826 | * Work queue handler triggered to process pending |
827 | * retries on an ioctx. Takes on the aio issuer's |
828 | * mm context before running the iocbs, so that |
829 | * copy_xxx_user operates on the issuer's address |
830 | * space. |
831 | * Run on aiod's context. |
832 | */ |
833 | static void aio_kick_handler(struct work_struct *work) |
834 | { |
835 | struct kioctx *ctx = container_of(work, struct kioctx, wq.work); |
836 | mm_segment_t oldfs = get_fs(); |
837 | struct mm_struct *mm; |
838 | int requeue; |
839 | |
840 | set_fs(USER_DS); |
841 | use_mm(ctx->mm); |
842 | spin_lock_irq(&ctx->ctx_lock); |
843 | requeue =__aio_run_iocbs(ctx); |
844 | mm = ctx->mm; |
845 | spin_unlock_irq(&ctx->ctx_lock); |
846 | unuse_mm(mm); |
847 | set_fs(oldfs); |
848 | /* |
849 | * we're in a worker thread already, don't use queue_delayed_work, |
850 | */ |
851 | if (requeue) |
852 | queue_delayed_work(aio_wq, &ctx->wq, 0); |
853 | } |
854 | |
855 | |
856 | /* |
857 | * Called by kick_iocb to queue the kiocb for retry |
858 | * and if required activate the aio work queue to process |
859 | * it |
860 | */ |
861 | static void try_queue_kicked_iocb(struct kiocb *iocb) |
862 | { |
863 | struct kioctx *ctx = iocb->ki_ctx; |
864 | unsigned long flags; |
865 | int run = 0; |
866 | |
867 | spin_lock_irqsave(&ctx->ctx_lock, flags); |
868 | /* set this inside the lock so that we can't race with aio_run_iocb() |
869 | * testing it and putting the iocb on the run list under the lock */ |
870 | if (!kiocbTryKick(iocb)) |
871 | run = __queue_kicked_iocb(iocb); |
872 | spin_unlock_irqrestore(&ctx->ctx_lock, flags); |
873 | if (run) |
874 | aio_queue_work(ctx); |
875 | } |
876 | |
877 | /* |
878 | * kick_iocb: |
879 | * Called typically from a wait queue callback context |
880 | * to trigger a retry of the iocb. |
881 | * The retry is usually executed by aio workqueue |
882 | * threads (See aio_kick_handler). |
883 | */ |
884 | void kick_iocb(struct kiocb *iocb) |
885 | { |
886 | /* sync iocbs are easy: they can only ever be executing from a |
887 | * single context. */ |
888 | if (is_sync_kiocb(iocb)) { |
889 | kiocbSetKicked(iocb); |
890 | wake_up_process(iocb->ki_obj.tsk); |
891 | return; |
892 | } |
893 | |
894 | try_queue_kicked_iocb(iocb); |
895 | } |
896 | EXPORT_SYMBOL(kick_iocb); |
897 | |
898 | /* aio_complete |
899 | * Called when the io request on the given iocb is complete. |
900 | * Returns true if this is the last user of the request. The |
901 | * only other user of the request can be the cancellation code. |
902 | */ |
903 | int aio_complete(struct kiocb *iocb, long res, long res2) |
904 | { |
905 | struct kioctx *ctx = iocb->ki_ctx; |
906 | struct aio_ring_info *info; |
907 | struct aio_ring *ring; |
908 | struct io_event *event; |
909 | unsigned long flags; |
910 | unsigned long tail; |
911 | int ret; |
912 | |
913 | /* |
914 | * Special case handling for sync iocbs: |
915 | * - events go directly into the iocb for fast handling |
916 | * - the sync task with the iocb in its stack holds the single iocb |
917 | * ref, no other paths have a way to get another ref |
918 | * - the sync task helpfully left a reference to itself in the iocb |
919 | */ |
920 | if (is_sync_kiocb(iocb)) { |
921 | BUG_ON(iocb->ki_users != 1); |
922 | iocb->ki_user_data = res; |
923 | iocb->ki_users = 0; |
924 | wake_up_process(iocb->ki_obj.tsk); |
925 | return 1; |
926 | } |
927 | |
928 | info = &ctx->ring_info; |
929 | |
930 | /* add a completion event to the ring buffer. |
931 | * must be done holding ctx->ctx_lock to prevent |
932 | * other code from messing with the tail |
933 | * pointer since we might be called from irq |
934 | * context. |
935 | */ |
936 | spin_lock_irqsave(&ctx->ctx_lock, flags); |
937 | |
938 | if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list)) |
939 | list_del_init(&iocb->ki_run_list); |
940 | |
941 | /* |
942 | * cancelled requests don't get events, userland was given one |
943 | * when the event got cancelled. |
944 | */ |
945 | if (kiocbIsCancelled(iocb)) |
946 | goto put_rq; |
947 | |
948 | ring = kmap_atomic(info->ring_pages[0], KM_IRQ1); |
949 | |
950 | tail = info->tail; |
951 | event = aio_ring_event(info, tail, KM_IRQ0); |
952 | if (++tail >= info->nr) |
953 | tail = 0; |
954 | |
955 | event->obj = (u64)(unsigned long)iocb->ki_obj.user; |
956 | event->data = iocb->ki_user_data; |
957 | event->res = res; |
958 | event->res2 = res2; |
959 | |
960 | dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n", |
961 | ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data, |
962 | res, res2); |
963 | |
964 | /* after flagging the request as done, we |
965 | * must never even look at it again |
966 | */ |
967 | smp_wmb(); /* make event visible before updating tail */ |
968 | |
969 | info->tail = tail; |
970 | ring->tail = tail; |
971 | |
972 | put_aio_ring_event(event, KM_IRQ0); |
973 | kunmap_atomic(ring, KM_IRQ1); |
974 | |
975 | pr_debug("added to ring %p at [%lu]\n", iocb, tail); |
976 | |
977 | /* |
978 | * Check if the user asked us to deliver the result through an |
979 | * eventfd. The eventfd_signal() function is safe to be called |
980 | * from IRQ context. |
981 | */ |
982 | if (iocb->ki_eventfd != NULL) |
983 | eventfd_signal(iocb->ki_eventfd, 1); |
984 | |
985 | put_rq: |
986 | /* everything turned out well, dispose of the aiocb. */ |
987 | ret = __aio_put_req(ctx, iocb); |
988 | |
989 | /* |
990 | * We have to order our ring_info tail store above and test |
991 | * of the wait list below outside the wait lock. This is |
992 | * like in wake_up_bit() where clearing a bit has to be |
993 | * ordered with the unlocked test. |
994 | */ |
995 | smp_mb(); |
996 | |
997 | if (waitqueue_active(&ctx->wait)) |
998 | wake_up(&ctx->wait); |
999 | |
1000 | spin_unlock_irqrestore(&ctx->ctx_lock, flags); |
1001 | return ret; |
1002 | } |
1003 | EXPORT_SYMBOL(aio_complete); |
1004 | |
1005 | /* aio_read_evt |
1006 | * Pull an event off of the ioctx's event ring. Returns the number of |
1007 | * events fetched (0 or 1 ;-) |
1008 | * FIXME: make this use cmpxchg. |
1009 | * TODO: make the ringbuffer user mmap()able (requires FIXME). |
1010 | */ |
1011 | static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent) |
1012 | { |
1013 | struct aio_ring_info *info = &ioctx->ring_info; |
1014 | struct aio_ring *ring; |
1015 | unsigned long head; |
1016 | int ret = 0; |
1017 | |
1018 | ring = kmap_atomic(info->ring_pages[0], KM_USER0); |
1019 | dprintk("in aio_read_evt h%lu t%lu m%lu\n", |
1020 | (unsigned long)ring->head, (unsigned long)ring->tail, |
1021 | (unsigned long)ring->nr); |
1022 | |
1023 | if (ring->head == ring->tail) |
1024 | goto out; |
1025 | |
1026 | spin_lock(&info->ring_lock); |
1027 | |
1028 | head = ring->head % info->nr; |
1029 | if (head != ring->tail) { |
1030 | struct io_event *evp = aio_ring_event(info, head, KM_USER1); |
1031 | *ent = *evp; |
1032 | head = (head + 1) % info->nr; |
1033 | smp_mb(); /* finish reading the event before updatng the head */ |
1034 | ring->head = head; |
1035 | ret = 1; |
1036 | put_aio_ring_event(evp, KM_USER1); |
1037 | } |
1038 | spin_unlock(&info->ring_lock); |
1039 | |
1040 | out: |
1041 | kunmap_atomic(ring, KM_USER0); |
1042 | dprintk("leaving aio_read_evt: %d h%lu t%lu\n", ret, |
1043 | (unsigned long)ring->head, (unsigned long)ring->tail); |
1044 | return ret; |
1045 | } |
1046 | |
1047 | struct aio_timeout { |
1048 | struct timer_list timer; |
1049 | int timed_out; |
1050 | struct task_struct *p; |
1051 | }; |
1052 | |
1053 | static void timeout_func(unsigned long data) |
1054 | { |
1055 | struct aio_timeout *to = (struct aio_timeout *)data; |
1056 | |
1057 | to->timed_out = 1; |
1058 | wake_up_process(to->p); |
1059 | } |
1060 | |
1061 | static inline void init_timeout(struct aio_timeout *to) |
1062 | { |
1063 | setup_timer_on_stack(&to->timer, timeout_func, (unsigned long) to); |
1064 | to->timed_out = 0; |
1065 | to->p = current; |
1066 | } |
1067 | |
1068 | static inline void set_timeout(long start_jiffies, struct aio_timeout *to, |
1069 | const struct timespec *ts) |
1070 | { |
1071 | to->timer.expires = start_jiffies + timespec_to_jiffies(ts); |
1072 | if (time_after(to->timer.expires, jiffies)) |
1073 | add_timer(&to->timer); |
1074 | else |
1075 | to->timed_out = 1; |
1076 | } |
1077 | |
1078 | static inline void clear_timeout(struct aio_timeout *to) |
1079 | { |
1080 | del_singleshot_timer_sync(&to->timer); |
1081 | } |
1082 | |
1083 | static int read_events(struct kioctx *ctx, |
1084 | long min_nr, long nr, |
1085 | struct io_event __user *event, |
1086 | struct timespec __user *timeout) |
1087 | { |
1088 | long start_jiffies = jiffies; |
1089 | struct task_struct *tsk = current; |
1090 | DECLARE_WAITQUEUE(wait, tsk); |
1091 | int ret; |
1092 | int i = 0; |
1093 | struct io_event ent; |
1094 | struct aio_timeout to; |
1095 | int retry = 0; |
1096 | |
1097 | /* needed to zero any padding within an entry (there shouldn't be |
1098 | * any, but C is fun! |
1099 | */ |
1100 | memset(&ent, 0, sizeof(ent)); |
1101 | retry: |
1102 | ret = 0; |
1103 | while (likely(i < nr)) { |
1104 | ret = aio_read_evt(ctx, &ent); |
1105 | if (unlikely(ret <= 0)) |
1106 | break; |
1107 | |
1108 | dprintk("read event: %Lx %Lx %Lx %Lx\n", |
1109 | ent.data, ent.obj, ent.res, ent.res2); |
1110 | |
1111 | /* Could we split the check in two? */ |
1112 | ret = -EFAULT; |
1113 | if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { |
1114 | dprintk("aio: lost an event due to EFAULT.\n"); |
1115 | break; |
1116 | } |
1117 | ret = 0; |
1118 | |
1119 | /* Good, event copied to userland, update counts. */ |
1120 | event ++; |
1121 | i ++; |
1122 | } |
1123 | |
1124 | if (min_nr <= i) |
1125 | return i; |
1126 | if (ret) |
1127 | return ret; |
1128 | |
1129 | /* End fast path */ |
1130 | |
1131 | /* racey check, but it gets redone */ |
1132 | if (!retry && unlikely(!list_empty(&ctx->run_list))) { |
1133 | retry = 1; |
1134 | aio_run_all_iocbs(ctx); |
1135 | goto retry; |
1136 | } |
1137 | |
1138 | init_timeout(&to); |
1139 | if (timeout) { |
1140 | struct timespec ts; |
1141 | ret = -EFAULT; |
1142 | if (unlikely(copy_from_user(&ts, timeout, sizeof(ts)))) |
1143 | goto out; |
1144 | |
1145 | set_timeout(start_jiffies, &to, &ts); |
1146 | } |
1147 | |
1148 | while (likely(i < nr)) { |
1149 | add_wait_queue_exclusive(&ctx->wait, &wait); |
1150 | do { |
1151 | set_task_state(tsk, TASK_INTERRUPTIBLE); |
1152 | ret = aio_read_evt(ctx, &ent); |
1153 | if (ret) |
1154 | break; |
1155 | if (min_nr <= i) |
1156 | break; |
1157 | if (unlikely(ctx->dead)) { |
1158 | ret = -EINVAL; |
1159 | break; |
1160 | } |
1161 | if (to.timed_out) /* Only check after read evt */ |
1162 | break; |
1163 | /* Try to only show up in io wait if there are ops |
1164 | * in flight */ |
1165 | if (ctx->reqs_active) |
1166 | io_schedule(); |
1167 | else |
1168 | schedule(); |
1169 | if (signal_pending(tsk)) { |
1170 | ret = -EINTR; |
1171 | break; |
1172 | } |
1173 | /*ret = aio_read_evt(ctx, &ent);*/ |
1174 | } while (1) ; |
1175 | |
1176 | set_task_state(tsk, TASK_RUNNING); |
1177 | remove_wait_queue(&ctx->wait, &wait); |
1178 | |
1179 | if (unlikely(ret <= 0)) |
1180 | break; |
1181 | |
1182 | ret = -EFAULT; |
1183 | if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { |
1184 | dprintk("aio: lost an event due to EFAULT.\n"); |
1185 | break; |
1186 | } |
1187 | |
1188 | /* Good, event copied to userland, update counts. */ |
1189 | event ++; |
1190 | i ++; |
1191 | } |
1192 | |
1193 | if (timeout) |
1194 | clear_timeout(&to); |
1195 | out: |
1196 | destroy_timer_on_stack(&to.timer); |
1197 | return i ? i : ret; |
1198 | } |
1199 | |
1200 | /* Take an ioctx and remove it from the list of ioctx's. Protects |
1201 | * against races with itself via ->dead. |
1202 | */ |
1203 | static void io_destroy(struct kioctx *ioctx) |
1204 | { |
1205 | struct mm_struct *mm = current->mm; |
1206 | int was_dead; |
1207 | |
1208 | /* delete the entry from the list is someone else hasn't already */ |
1209 | spin_lock(&mm->ioctx_lock); |
1210 | was_dead = ioctx->dead; |
1211 | ioctx->dead = 1; |
1212 | hlist_del_rcu(&ioctx->list); |
1213 | spin_unlock(&mm->ioctx_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 | |
1222 | /* |
1223 | * Wake up any waiters. The setting of ctx->dead must be seen |
1224 | * by other CPUs at this point. Right now, we rely on the |
1225 | * locking done by the above calls to ensure this consistency. |
1226 | */ |
1227 | wake_up(&ioctx->wait); |
1228 | put_ioctx(ioctx); /* once for the lookup */ |
1229 | } |
1230 | |
1231 | /* sys_io_setup: |
1232 | * Create an aio_context capable of receiving at least nr_events. |
1233 | * ctxp must not point to an aio_context that already exists, and |
1234 | * must be initialized to 0 prior to the call. On successful |
1235 | * creation of the aio_context, *ctxp is filled in with the resulting |
1236 | * handle. May fail with -EINVAL if *ctxp is not initialized, |
1237 | * if the specified nr_events exceeds internal limits. May fail |
1238 | * with -EAGAIN if the specified nr_events exceeds the user's limit |
1239 | * of available events. May fail with -ENOMEM if insufficient kernel |
1240 | * resources are available. May fail with -EFAULT if an invalid |
1241 | * pointer is passed for ctxp. Will fail with -ENOSYS if not |
1242 | * implemented. |
1243 | */ |
1244 | SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp) |
1245 | { |
1246 | struct kioctx *ioctx = NULL; |
1247 | unsigned long ctx; |
1248 | long ret; |
1249 | |
1250 | ret = get_user(ctx, ctxp); |
1251 | if (unlikely(ret)) |
1252 | goto out; |
1253 | |
1254 | ret = -EINVAL; |
1255 | if (unlikely(ctx || nr_events == 0)) { |
1256 | pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n", |
1257 | ctx, nr_events); |
1258 | goto out; |
1259 | } |
1260 | |
1261 | ioctx = ioctx_alloc(nr_events); |
1262 | ret = PTR_ERR(ioctx); |
1263 | if (!IS_ERR(ioctx)) { |
1264 | ret = put_user(ioctx->user_id, ctxp); |
1265 | if (!ret) |
1266 | return 0; |
1267 | |
1268 | get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */ |
1269 | io_destroy(ioctx); |
1270 | } |
1271 | |
1272 | out: |
1273 | return ret; |
1274 | } |
1275 | |
1276 | /* sys_io_destroy: |
1277 | * Destroy the aio_context specified. May cancel any outstanding |
1278 | * AIOs and block on completion. Will fail with -ENOSYS if not |
1279 | * implemented. May fail with -EFAULT if the context pointed to |
1280 | * is invalid. |
1281 | */ |
1282 | SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx) |
1283 | { |
1284 | struct kioctx *ioctx = lookup_ioctx(ctx); |
1285 | if (likely(NULL != ioctx)) { |
1286 | io_destroy(ioctx); |
1287 | return 0; |
1288 | } |
1289 | pr_debug("EINVAL: io_destroy: invalid context id\n"); |
1290 | return -EINVAL; |
1291 | } |
1292 | |
1293 | static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret) |
1294 | { |
1295 | struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg]; |
1296 | |
1297 | BUG_ON(ret <= 0); |
1298 | |
1299 | while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) { |
1300 | ssize_t this = min((ssize_t)iov->iov_len, ret); |
1301 | iov->iov_base += this; |
1302 | iov->iov_len -= this; |
1303 | iocb->ki_left -= this; |
1304 | ret -= this; |
1305 | if (iov->iov_len == 0) { |
1306 | iocb->ki_cur_seg++; |
1307 | iov++; |
1308 | } |
1309 | } |
1310 | |
1311 | /* the caller should not have done more io than what fit in |
1312 | * the remaining iovecs */ |
1313 | BUG_ON(ret > 0 && iocb->ki_left == 0); |
1314 | } |
1315 | |
1316 | static ssize_t aio_rw_vect_retry(struct kiocb *iocb) |
1317 | { |
1318 | struct file *file = iocb->ki_filp; |
1319 | struct address_space *mapping = file->f_mapping; |
1320 | struct inode *inode = mapping->host; |
1321 | ssize_t (*rw_op)(struct kiocb *, const struct iovec *, |
1322 | unsigned long, loff_t); |
1323 | ssize_t ret = 0; |
1324 | unsigned short opcode; |
1325 | |
1326 | if ((iocb->ki_opcode == IOCB_CMD_PREADV) || |
1327 | (iocb->ki_opcode == IOCB_CMD_PREAD)) { |
1328 | rw_op = file->f_op->aio_read; |
1329 | opcode = IOCB_CMD_PREADV; |
1330 | } else { |
1331 | rw_op = file->f_op->aio_write; |
1332 | opcode = IOCB_CMD_PWRITEV; |
1333 | } |
1334 | |
1335 | /* This matches the pread()/pwrite() logic */ |
1336 | if (iocb->ki_pos < 0) |
1337 | return -EINVAL; |
1338 | |
1339 | do { |
1340 | ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg], |
1341 | iocb->ki_nr_segs - iocb->ki_cur_seg, |
1342 | iocb->ki_pos); |
1343 | if (ret > 0) |
1344 | aio_advance_iovec(iocb, ret); |
1345 | |
1346 | /* retry all partial writes. retry partial reads as long as its a |
1347 | * regular file. */ |
1348 | } while (ret > 0 && iocb->ki_left > 0 && |
1349 | (opcode == IOCB_CMD_PWRITEV || |
1350 | (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode)))); |
1351 | |
1352 | /* This means we must have transferred all that we could */ |
1353 | /* No need to retry anymore */ |
1354 | if ((ret == 0) || (iocb->ki_left == 0)) |
1355 | ret = iocb->ki_nbytes - iocb->ki_left; |
1356 | |
1357 | /* If we managed to write some out we return that, rather than |
1358 | * the eventual error. */ |
1359 | if (opcode == IOCB_CMD_PWRITEV |
1360 | && ret < 0 && ret != -EIOCBQUEUED && ret != -EIOCBRETRY |
1361 | && iocb->ki_nbytes - iocb->ki_left) |
1362 | ret = iocb->ki_nbytes - iocb->ki_left; |
1363 | |
1364 | return ret; |
1365 | } |
1366 | |
1367 | static ssize_t aio_fdsync(struct kiocb *iocb) |
1368 | { |
1369 | struct file *file = iocb->ki_filp; |
1370 | ssize_t ret = -EINVAL; |
1371 | |
1372 | if (file->f_op->aio_fsync) |
1373 | ret = file->f_op->aio_fsync(iocb, 1); |
1374 | return ret; |
1375 | } |
1376 | |
1377 | static ssize_t aio_fsync(struct kiocb *iocb) |
1378 | { |
1379 | struct file *file = iocb->ki_filp; |
1380 | ssize_t ret = -EINVAL; |
1381 | |
1382 | if (file->f_op->aio_fsync) |
1383 | ret = file->f_op->aio_fsync(iocb, 0); |
1384 | return ret; |
1385 | } |
1386 | |
1387 | static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb) |
1388 | { |
1389 | ssize_t ret; |
1390 | |
1391 | ret = rw_copy_check_uvector(type, (struct iovec __user *)kiocb->ki_buf, |
1392 | kiocb->ki_nbytes, 1, |
1393 | &kiocb->ki_inline_vec, &kiocb->ki_iovec); |
1394 | if (ret < 0) |
1395 | goto out; |
1396 | |
1397 | kiocb->ki_nr_segs = kiocb->ki_nbytes; |
1398 | kiocb->ki_cur_seg = 0; |
1399 | /* ki_nbytes/left now reflect bytes instead of segs */ |
1400 | kiocb->ki_nbytes = ret; |
1401 | kiocb->ki_left = ret; |
1402 | |
1403 | ret = 0; |
1404 | out: |
1405 | return ret; |
1406 | } |
1407 | |
1408 | static ssize_t aio_setup_single_vector(struct kiocb *kiocb) |
1409 | { |
1410 | kiocb->ki_iovec = &kiocb->ki_inline_vec; |
1411 | kiocb->ki_iovec->iov_base = kiocb->ki_buf; |
1412 | kiocb->ki_iovec->iov_len = kiocb->ki_left; |
1413 | kiocb->ki_nr_segs = 1; |
1414 | kiocb->ki_cur_seg = 0; |
1415 | return 0; |
1416 | } |
1417 | |
1418 | /* |
1419 | * aio_setup_iocb: |
1420 | * Performs the initial checks and aio retry method |
1421 | * setup for the kiocb at the time of io submission. |
1422 | */ |
1423 | static ssize_t aio_setup_iocb(struct kiocb *kiocb) |
1424 | { |
1425 | struct file *file = kiocb->ki_filp; |
1426 | ssize_t ret = 0; |
1427 | |
1428 | switch (kiocb->ki_opcode) { |
1429 | case IOCB_CMD_PREAD: |
1430 | ret = -EBADF; |
1431 | if (unlikely(!(file->f_mode & FMODE_READ))) |
1432 | break; |
1433 | ret = -EFAULT; |
1434 | if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf, |
1435 | kiocb->ki_left))) |
1436 | break; |
1437 | ret = security_file_permission(file, MAY_READ); |
1438 | if (unlikely(ret)) |
1439 | break; |
1440 | ret = aio_setup_single_vector(kiocb); |
1441 | if (ret) |
1442 | break; |
1443 | ret = -EINVAL; |
1444 | if (file->f_op->aio_read) |
1445 | kiocb->ki_retry = aio_rw_vect_retry; |
1446 | break; |
1447 | case IOCB_CMD_PWRITE: |
1448 | ret = -EBADF; |
1449 | if (unlikely(!(file->f_mode & FMODE_WRITE))) |
1450 | break; |
1451 | ret = -EFAULT; |
1452 | if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf, |
1453 | kiocb->ki_left))) |
1454 | break; |
1455 | ret = security_file_permission(file, MAY_WRITE); |
1456 | if (unlikely(ret)) |
1457 | break; |
1458 | ret = aio_setup_single_vector(kiocb); |
1459 | if (ret) |
1460 | break; |
1461 | ret = -EINVAL; |
1462 | if (file->f_op->aio_write) |
1463 | kiocb->ki_retry = aio_rw_vect_retry; |
1464 | break; |
1465 | case IOCB_CMD_PREADV: |
1466 | ret = -EBADF; |
1467 | if (unlikely(!(file->f_mode & FMODE_READ))) |
1468 | break; |
1469 | ret = security_file_permission(file, MAY_READ); |
1470 | if (unlikely(ret)) |
1471 | break; |
1472 | ret = aio_setup_vectored_rw(READ, kiocb); |
1473 | if (ret) |
1474 | break; |
1475 | ret = -EINVAL; |
1476 | if (file->f_op->aio_read) |
1477 | kiocb->ki_retry = aio_rw_vect_retry; |
1478 | break; |
1479 | case IOCB_CMD_PWRITEV: |
1480 | ret = -EBADF; |
1481 | if (unlikely(!(file->f_mode & FMODE_WRITE))) |
1482 | break; |
1483 | ret = security_file_permission(file, MAY_WRITE); |
1484 | if (unlikely(ret)) |
1485 | break; |
1486 | ret = aio_setup_vectored_rw(WRITE, kiocb); |
1487 | if (ret) |
1488 | break; |
1489 | ret = -EINVAL; |
1490 | if (file->f_op->aio_write) |
1491 | kiocb->ki_retry = aio_rw_vect_retry; |
1492 | break; |
1493 | case IOCB_CMD_FDSYNC: |
1494 | ret = -EINVAL; |
1495 | if (file->f_op->aio_fsync) |
1496 | kiocb->ki_retry = aio_fdsync; |
1497 | break; |
1498 | case IOCB_CMD_FSYNC: |
1499 | ret = -EINVAL; |
1500 | if (file->f_op->aio_fsync) |
1501 | kiocb->ki_retry = aio_fsync; |
1502 | break; |
1503 | default: |
1504 | dprintk("EINVAL: io_submit: no operation provided\n"); |
1505 | ret = -EINVAL; |
1506 | } |
1507 | |
1508 | if (!kiocb->ki_retry) |
1509 | return ret; |
1510 | |
1511 | return 0; |
1512 | } |
1513 | |
1514 | static void aio_batch_add(struct address_space *mapping, |
1515 | struct hlist_head *batch_hash) |
1516 | { |
1517 | struct aio_batch_entry *abe; |
1518 | struct hlist_node *pos; |
1519 | unsigned bucket; |
1520 | |
1521 | bucket = hash_ptr(mapping, AIO_BATCH_HASH_BITS); |
1522 | hlist_for_each_entry(abe, pos, &batch_hash[bucket], list) { |
1523 | if (abe->mapping == mapping) |
1524 | return; |
1525 | } |
1526 | |
1527 | abe = mempool_alloc(abe_pool, GFP_KERNEL); |
1528 | BUG_ON(!igrab(mapping->host)); |
1529 | abe->mapping = mapping; |
1530 | hlist_add_head(&abe->list, &batch_hash[bucket]); |
1531 | return; |
1532 | } |
1533 | |
1534 | static void aio_batch_free(struct hlist_head *batch_hash) |
1535 | { |
1536 | struct aio_batch_entry *abe; |
1537 | struct hlist_node *pos, *n; |
1538 | int i; |
1539 | |
1540 | for (i = 0; i < AIO_BATCH_HASH_SIZE; i++) { |
1541 | hlist_for_each_entry_safe(abe, pos, n, &batch_hash[i], list) { |
1542 | blk_run_address_space(abe->mapping); |
1543 | iput(abe->mapping->host); |
1544 | hlist_del(&abe->list); |
1545 | mempool_free(abe, abe_pool); |
1546 | } |
1547 | } |
1548 | } |
1549 | |
1550 | static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, |
1551 | struct iocb *iocb, struct hlist_head *batch_hash) |
1552 | { |
1553 | struct kiocb *req; |
1554 | struct file *file; |
1555 | ssize_t ret; |
1556 | |
1557 | /* enforce forwards compatibility on users */ |
1558 | if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) { |
1559 | pr_debug("EINVAL: io_submit: reserve field set\n"); |
1560 | return -EINVAL; |
1561 | } |
1562 | |
1563 | /* prevent overflows */ |
1564 | if (unlikely( |
1565 | (iocb->aio_buf != (unsigned long)iocb->aio_buf) || |
1566 | (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) || |
1567 | ((ssize_t)iocb->aio_nbytes < 0) |
1568 | )) { |
1569 | pr_debug("EINVAL: io_submit: overflow check\n"); |
1570 | return -EINVAL; |
1571 | } |
1572 | |
1573 | file = fget(iocb->aio_fildes); |
1574 | if (unlikely(!file)) |
1575 | return -EBADF; |
1576 | |
1577 | req = aio_get_req(ctx); /* returns with 2 references to req */ |
1578 | if (unlikely(!req)) { |
1579 | fput(file); |
1580 | return -EAGAIN; |
1581 | } |
1582 | req->ki_filp = file; |
1583 | if (iocb->aio_flags & IOCB_FLAG_RESFD) { |
1584 | /* |
1585 | * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an |
1586 | * instance of the file* now. The file descriptor must be |
1587 | * an eventfd() fd, and will be signaled for each completed |
1588 | * event using the eventfd_signal() function. |
1589 | */ |
1590 | req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd); |
1591 | if (IS_ERR(req->ki_eventfd)) { |
1592 | ret = PTR_ERR(req->ki_eventfd); |
1593 | req->ki_eventfd = NULL; |
1594 | goto out_put_req; |
1595 | } |
1596 | } |
1597 | |
1598 | ret = put_user(req->ki_key, &user_iocb->aio_key); |
1599 | if (unlikely(ret)) { |
1600 | dprintk("EFAULT: aio_key\n"); |
1601 | goto out_put_req; |
1602 | } |
1603 | |
1604 | req->ki_obj.user = user_iocb; |
1605 | req->ki_user_data = iocb->aio_data; |
1606 | req->ki_pos = iocb->aio_offset; |
1607 | |
1608 | req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf; |
1609 | req->ki_left = req->ki_nbytes = iocb->aio_nbytes; |
1610 | req->ki_opcode = iocb->aio_lio_opcode; |
1611 | |
1612 | ret = aio_setup_iocb(req); |
1613 | |
1614 | if (ret) |
1615 | goto out_put_req; |
1616 | |
1617 | spin_lock_irq(&ctx->ctx_lock); |
1618 | aio_run_iocb(req); |
1619 | if (!list_empty(&ctx->run_list)) { |
1620 | /* drain the run list */ |
1621 | while (__aio_run_iocbs(ctx)) |
1622 | ; |
1623 | } |
1624 | spin_unlock_irq(&ctx->ctx_lock); |
1625 | if (req->ki_opcode == IOCB_CMD_PREAD || |
1626 | req->ki_opcode == IOCB_CMD_PREADV || |
1627 | req->ki_opcode == IOCB_CMD_PWRITE || |
1628 | req->ki_opcode == IOCB_CMD_PWRITEV) |
1629 | aio_batch_add(file->f_mapping, batch_hash); |
1630 | |
1631 | aio_put_req(req); /* drop extra ref to req */ |
1632 | return 0; |
1633 | |
1634 | out_put_req: |
1635 | aio_put_req(req); /* drop extra ref to req */ |
1636 | aio_put_req(req); /* drop i/o ref to req */ |
1637 | return ret; |
1638 | } |
1639 | |
1640 | /* sys_io_submit: |
1641 | * Queue the nr iocbs pointed to by iocbpp for processing. Returns |
1642 | * the number of iocbs queued. May return -EINVAL if the aio_context |
1643 | * specified by ctx_id is invalid, if nr is < 0, if the iocb at |
1644 | * *iocbpp[0] is not properly initialized, if the operation specified |
1645 | * is invalid for the file descriptor in the iocb. May fail with |
1646 | * -EFAULT if any of the data structures point to invalid data. May |
1647 | * fail with -EBADF if the file descriptor specified in the first |
1648 | * iocb is invalid. May fail with -EAGAIN if insufficient resources |
1649 | * are available to queue any iocbs. Will return 0 if nr is 0. Will |
1650 | * fail with -ENOSYS if not implemented. |
1651 | */ |
1652 | SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr, |
1653 | struct iocb __user * __user *, iocbpp) |
1654 | { |
1655 | struct kioctx *ctx; |
1656 | long ret = 0; |
1657 | int i; |
1658 | struct hlist_head batch_hash[AIO_BATCH_HASH_SIZE] = { { 0, }, }; |
1659 | |
1660 | if (unlikely(nr < 0)) |
1661 | return -EINVAL; |
1662 | |
1663 | if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp))))) |
1664 | return -EFAULT; |
1665 | |
1666 | ctx = lookup_ioctx(ctx_id); |
1667 | if (unlikely(!ctx)) { |
1668 | pr_debug("EINVAL: io_submit: invalid context id\n"); |
1669 | return -EINVAL; |
1670 | } |
1671 | |
1672 | /* |
1673 | * AKPM: should this return a partial result if some of the IOs were |
1674 | * successfully submitted? |
1675 | */ |
1676 | for (i=0; i<nr; i++) { |
1677 | struct iocb __user *user_iocb; |
1678 | struct iocb tmp; |
1679 | |
1680 | if (unlikely(__get_user(user_iocb, iocbpp + i))) { |
1681 | ret = -EFAULT; |
1682 | break; |
1683 | } |
1684 | |
1685 | if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) { |
1686 | ret = -EFAULT; |
1687 | break; |
1688 | } |
1689 | |
1690 | ret = io_submit_one(ctx, user_iocb, &tmp, batch_hash); |
1691 | if (ret) |
1692 | break; |
1693 | } |
1694 | aio_batch_free(batch_hash); |
1695 | |
1696 | put_ioctx(ctx); |
1697 | return i ? i : ret; |
1698 | } |
1699 | |
1700 | /* lookup_kiocb |
1701 | * Finds a given iocb for cancellation. |
1702 | */ |
1703 | static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, |
1704 | u32 key) |
1705 | { |
1706 | struct list_head *pos; |
1707 | |
1708 | assert_spin_locked(&ctx->ctx_lock); |
1709 | |
1710 | /* TODO: use a hash or array, this sucks. */ |
1711 | list_for_each(pos, &ctx->active_reqs) { |
1712 | struct kiocb *kiocb = list_kiocb(pos); |
1713 | if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key) |
1714 | return kiocb; |
1715 | } |
1716 | return NULL; |
1717 | } |
1718 | |
1719 | /* sys_io_cancel: |
1720 | * Attempts to cancel an iocb previously passed to io_submit. If |
1721 | * the operation is successfully cancelled, the resulting event is |
1722 | * copied into the memory pointed to by result without being placed |
1723 | * into the completion queue and 0 is returned. May fail with |
1724 | * -EFAULT if any of the data structures pointed to are invalid. |
1725 | * May fail with -EINVAL if aio_context specified by ctx_id is |
1726 | * invalid. May fail with -EAGAIN if the iocb specified was not |
1727 | * cancelled. Will fail with -ENOSYS if not implemented. |
1728 | */ |
1729 | SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb, |
1730 | struct io_event __user *, result) |
1731 | { |
1732 | int (*cancel)(struct kiocb *iocb, struct io_event *res); |
1733 | struct kioctx *ctx; |
1734 | struct kiocb *kiocb; |
1735 | u32 key; |
1736 | int ret; |
1737 | |
1738 | ret = get_user(key, &iocb->aio_key); |
1739 | if (unlikely(ret)) |
1740 | return -EFAULT; |
1741 | |
1742 | ctx = lookup_ioctx(ctx_id); |
1743 | if (unlikely(!ctx)) |
1744 | return -EINVAL; |
1745 | |
1746 | spin_lock_irq(&ctx->ctx_lock); |
1747 | ret = -EAGAIN; |
1748 | kiocb = lookup_kiocb(ctx, iocb, key); |
1749 | if (kiocb && kiocb->ki_cancel) { |
1750 | cancel = kiocb->ki_cancel; |
1751 | kiocb->ki_users ++; |
1752 | kiocbSetCancelled(kiocb); |
1753 | } else |
1754 | cancel = NULL; |
1755 | spin_unlock_irq(&ctx->ctx_lock); |
1756 | |
1757 | if (NULL != cancel) { |
1758 | struct io_event tmp; |
1759 | pr_debug("calling cancel\n"); |
1760 | memset(&tmp, 0, sizeof(tmp)); |
1761 | tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user; |
1762 | tmp.data = kiocb->ki_user_data; |
1763 | ret = cancel(kiocb, &tmp); |
1764 | if (!ret) { |
1765 | /* Cancellation succeeded -- copy the result |
1766 | * into the user's buffer. |
1767 | */ |
1768 | if (copy_to_user(result, &tmp, sizeof(tmp))) |
1769 | ret = -EFAULT; |
1770 | } |
1771 | } else |
1772 | ret = -EINVAL; |
1773 | |
1774 | put_ioctx(ctx); |
1775 | |
1776 | return ret; |
1777 | } |
1778 | |
1779 | /* io_getevents: |
1780 | * Attempts to read at least min_nr events and up to nr events from |
1781 | * the completion queue for the aio_context specified by ctx_id. May |
1782 | * fail with -EINVAL if ctx_id is invalid, if min_nr is out of range, |
1783 | * if nr is out of range, if when is out of range. May fail with |
1784 | * -EFAULT if any of the memory specified to is invalid. May return |
1785 | * 0 or < min_nr if no events are available and the timeout specified |
1786 | * by when has elapsed, where when == NULL specifies an infinite |
1787 | * timeout. Note that the timeout pointed to by when is relative and |
1788 | * will be updated if not NULL and the operation blocks. Will fail |
1789 | * with -ENOSYS if not implemented. |
1790 | */ |
1791 | SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id, |
1792 | long, min_nr, |
1793 | long, nr, |
1794 | struct io_event __user *, events, |
1795 | struct timespec __user *, timeout) |
1796 | { |
1797 | struct kioctx *ioctx = lookup_ioctx(ctx_id); |
1798 | long ret = -EINVAL; |
1799 | |
1800 | if (likely(ioctx)) { |
1801 | if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0)) |
1802 | ret = read_events(ioctx, min_nr, nr, events, timeout); |
1803 | put_ioctx(ioctx); |
1804 | } |
1805 | |
1806 | asmlinkage_protect(5, ret, ctx_id, min_nr, nr, events, timeout); |
1807 | return ret; |
1808 | } |
1809 |
Branches:
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javiroman/ks7010
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9