Commit | Line | Data |
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1da177e4 LT |
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 | ||
19 | #define DEBUG 0 | |
20 | ||
21 | #include <linux/sched.h> | |
22 | #include <linux/fs.h> | |
23 | #include <linux/file.h> | |
24 | #include <linux/mm.h> | |
25 | #include <linux/mman.h> | |
26 | #include <linux/slab.h> | |
27 | #include <linux/timer.h> | |
28 | #include <linux/aio.h> | |
29 | #include <linux/highmem.h> | |
30 | #include <linux/workqueue.h> | |
31 | #include <linux/security.h> | |
32 | ||
33 | #include <asm/kmap_types.h> | |
34 | #include <asm/uaccess.h> | |
35 | #include <asm/mmu_context.h> | |
36 | ||
37 | #if DEBUG > 1 | |
38 | #define dprintk printk | |
39 | #else | |
40 | #define dprintk(x...) do { ; } while (0) | |
41 | #endif | |
42 | ||
43 | long aio_run = 0; /* for testing only */ | |
44 | long aio_wakeups = 0; /* for testing only */ | |
45 | ||
46 | /*------ sysctl variables----*/ | |
47 | atomic_t aio_nr = ATOMIC_INIT(0); /* current system wide number of aio requests */ | |
48 | unsigned aio_max_nr = 0x10000; /* system wide maximum number of aio requests */ | |
49 | /*----end sysctl variables---*/ | |
50 | ||
51 | static kmem_cache_t *kiocb_cachep; | |
52 | static kmem_cache_t *kioctx_cachep; | |
53 | ||
54 | static struct workqueue_struct *aio_wq; | |
55 | ||
56 | /* Used for rare fput completion. */ | |
57 | static void aio_fput_routine(void *); | |
58 | static DECLARE_WORK(fput_work, aio_fput_routine, NULL); | |
59 | ||
60 | static DEFINE_SPINLOCK(fput_lock); | |
61 | LIST_HEAD(fput_head); | |
62 | ||
63 | static void aio_kick_handler(void *); | |
64 | ||
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 | */ | |
69 | static 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 | ||
83 | static 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 | ||
103 | static 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) { | |
126 | info->ring_pages = kmalloc(sizeof(struct page *) * nr_pages, GFP_KERNEL); | |
127 | if (!info->ring_pages) | |
128 | return -ENOMEM; | |
129 | memset(info->ring_pages, 0, sizeof(struct page *) * nr_pages); | |
130 | } | |
131 | ||
132 | info->mmap_size = nr_pages * PAGE_SIZE; | |
133 | dprintk("attempting mmap of %lu bytes\n", info->mmap_size); | |
134 | down_write(&ctx->mm->mmap_sem); | |
135 | info->mmap_base = do_mmap(NULL, 0, info->mmap_size, | |
136 | PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, | |
137 | 0); | |
138 | if (IS_ERR((void *)info->mmap_base)) { | |
139 | up_write(&ctx->mm->mmap_sem); | |
140 | printk("mmap err: %ld\n", -info->mmap_base); | |
141 | info->mmap_size = 0; | |
142 | aio_free_ring(ctx); | |
143 | return -EAGAIN; | |
144 | } | |
145 | ||
146 | dprintk("mmap address: 0x%08lx\n", info->mmap_base); | |
147 | info->nr_pages = get_user_pages(current, ctx->mm, | |
148 | info->mmap_base, nr_pages, | |
149 | 1, 0, info->ring_pages, NULL); | |
150 | up_write(&ctx->mm->mmap_sem); | |
151 | ||
152 | if (unlikely(info->nr_pages != nr_pages)) { | |
153 | aio_free_ring(ctx); | |
154 | return -EAGAIN; | |
155 | } | |
156 | ||
157 | ctx->user_id = info->mmap_base; | |
158 | ||
159 | info->nr = nr_events; /* trusted copy */ | |
160 | ||
161 | ring = kmap_atomic(info->ring_pages[0], KM_USER0); | |
162 | ring->nr = nr_events; /* user copy */ | |
163 | ring->id = ctx->user_id; | |
164 | ring->head = ring->tail = 0; | |
165 | ring->magic = AIO_RING_MAGIC; | |
166 | ring->compat_features = AIO_RING_COMPAT_FEATURES; | |
167 | ring->incompat_features = AIO_RING_INCOMPAT_FEATURES; | |
168 | ring->header_length = sizeof(struct aio_ring); | |
169 | kunmap_atomic(ring, KM_USER0); | |
170 | ||
171 | return 0; | |
172 | } | |
173 | ||
174 | ||
175 | /* aio_ring_event: returns a pointer to the event at the given index from | |
176 | * kmap_atomic(, km). Release the pointer with put_aio_ring_event(); | |
177 | */ | |
178 | #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event)) | |
179 | #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event)) | |
180 | #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE) | |
181 | ||
182 | #define aio_ring_event(info, nr, km) ({ \ | |
183 | unsigned pos = (nr) + AIO_EVENTS_OFFSET; \ | |
184 | struct io_event *__event; \ | |
185 | __event = kmap_atomic( \ | |
186 | (info)->ring_pages[pos / AIO_EVENTS_PER_PAGE], km); \ | |
187 | __event += pos % AIO_EVENTS_PER_PAGE; \ | |
188 | __event; \ | |
189 | }) | |
190 | ||
191 | #define put_aio_ring_event(event, km) do { \ | |
192 | struct io_event *__event = (event); \ | |
193 | (void)__event; \ | |
194 | kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK), km); \ | |
195 | } while(0) | |
196 | ||
197 | /* ioctx_alloc | |
198 | * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed. | |
199 | */ | |
200 | static struct kioctx *ioctx_alloc(unsigned nr_events) | |
201 | { | |
202 | struct mm_struct *mm; | |
203 | struct kioctx *ctx; | |
204 | ||
205 | /* Prevent overflows */ | |
206 | if ((nr_events > (0x10000000U / sizeof(struct io_event))) || | |
207 | (nr_events > (0x10000000U / sizeof(struct kiocb)))) { | |
208 | pr_debug("ENOMEM: nr_events too high\n"); | |
209 | return ERR_PTR(-EINVAL); | |
210 | } | |
211 | ||
212 | if (nr_events > aio_max_nr) | |
213 | return ERR_PTR(-EAGAIN); | |
214 | ||
215 | ctx = kmem_cache_alloc(kioctx_cachep, GFP_KERNEL); | |
216 | if (!ctx) | |
217 | return ERR_PTR(-ENOMEM); | |
218 | ||
219 | memset(ctx, 0, sizeof(*ctx)); | |
220 | ctx->max_reqs = nr_events; | |
221 | mm = ctx->mm = current->mm; | |
222 | atomic_inc(&mm->mm_count); | |
223 | ||
224 | atomic_set(&ctx->users, 1); | |
225 | spin_lock_init(&ctx->ctx_lock); | |
226 | spin_lock_init(&ctx->ring_info.ring_lock); | |
227 | init_waitqueue_head(&ctx->wait); | |
228 | ||
229 | INIT_LIST_HEAD(&ctx->active_reqs); | |
230 | INIT_LIST_HEAD(&ctx->run_list); | |
231 | INIT_WORK(&ctx->wq, aio_kick_handler, ctx); | |
232 | ||
233 | if (aio_setup_ring(ctx) < 0) | |
234 | goto out_freectx; | |
235 | ||
236 | /* limit the number of system wide aios */ | |
237 | atomic_add(ctx->max_reqs, &aio_nr); /* undone by __put_ioctx */ | |
238 | if (unlikely(atomic_read(&aio_nr) > aio_max_nr)) | |
239 | goto out_cleanup; | |
240 | ||
241 | /* now link into global list. kludge. FIXME */ | |
242 | write_lock(&mm->ioctx_list_lock); | |
243 | ctx->next = mm->ioctx_list; | |
244 | mm->ioctx_list = ctx; | |
245 | write_unlock(&mm->ioctx_list_lock); | |
246 | ||
247 | dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n", | |
248 | ctx, ctx->user_id, current->mm, ctx->ring_info.nr); | |
249 | return ctx; | |
250 | ||
251 | out_cleanup: | |
252 | atomic_sub(ctx->max_reqs, &aio_nr); | |
253 | ctx->max_reqs = 0; /* prevent __put_ioctx from sub'ing aio_nr */ | |
254 | __put_ioctx(ctx); | |
255 | return ERR_PTR(-EAGAIN); | |
256 | ||
257 | out_freectx: | |
258 | mmdrop(mm); | |
259 | kmem_cache_free(kioctx_cachep, ctx); | |
260 | ctx = ERR_PTR(-ENOMEM); | |
261 | ||
262 | dprintk("aio: error allocating ioctx %p\n", ctx); | |
263 | return ctx; | |
264 | } | |
265 | ||
266 | /* aio_cancel_all | |
267 | * Cancels all outstanding aio requests on an aio context. Used | |
268 | * when the processes owning a context have all exited to encourage | |
269 | * the rapid destruction of the kioctx. | |
270 | */ | |
271 | static void aio_cancel_all(struct kioctx *ctx) | |
272 | { | |
273 | int (*cancel)(struct kiocb *, struct io_event *); | |
274 | struct io_event res; | |
275 | spin_lock_irq(&ctx->ctx_lock); | |
276 | ctx->dead = 1; | |
277 | while (!list_empty(&ctx->active_reqs)) { | |
278 | struct list_head *pos = ctx->active_reqs.next; | |
279 | struct kiocb *iocb = list_kiocb(pos); | |
280 | list_del_init(&iocb->ki_list); | |
281 | cancel = iocb->ki_cancel; | |
282 | kiocbSetCancelled(iocb); | |
283 | if (cancel) { | |
284 | iocb->ki_users++; | |
285 | spin_unlock_irq(&ctx->ctx_lock); | |
286 | cancel(iocb, &res); | |
287 | spin_lock_irq(&ctx->ctx_lock); | |
288 | } | |
289 | } | |
290 | spin_unlock_irq(&ctx->ctx_lock); | |
291 | } | |
292 | ||
293 | void wait_for_all_aios(struct kioctx *ctx) | |
294 | { | |
295 | struct task_struct *tsk = current; | |
296 | DECLARE_WAITQUEUE(wait, tsk); | |
297 | ||
298 | if (!ctx->reqs_active) | |
299 | return; | |
300 | ||
301 | add_wait_queue(&ctx->wait, &wait); | |
302 | set_task_state(tsk, TASK_UNINTERRUPTIBLE); | |
303 | while (ctx->reqs_active) { | |
304 | schedule(); | |
305 | set_task_state(tsk, TASK_UNINTERRUPTIBLE); | |
306 | } | |
307 | __set_task_state(tsk, TASK_RUNNING); | |
308 | remove_wait_queue(&ctx->wait, &wait); | |
309 | } | |
310 | ||
311 | /* wait_on_sync_kiocb: | |
312 | * Waits on the given sync kiocb to complete. | |
313 | */ | |
314 | ssize_t fastcall wait_on_sync_kiocb(struct kiocb *iocb) | |
315 | { | |
316 | while (iocb->ki_users) { | |
317 | set_current_state(TASK_UNINTERRUPTIBLE); | |
318 | if (!iocb->ki_users) | |
319 | break; | |
320 | schedule(); | |
321 | } | |
322 | __set_current_state(TASK_RUNNING); | |
323 | return iocb->ki_user_data; | |
324 | } | |
325 | ||
326 | /* exit_aio: called when the last user of mm goes away. At this point, | |
327 | * there is no way for any new requests to be submited or any of the | |
328 | * io_* syscalls to be called on the context. However, there may be | |
329 | * outstanding requests which hold references to the context; as they | |
330 | * go away, they will call put_ioctx and release any pinned memory | |
331 | * associated with the request (held via struct page * references). | |
332 | */ | |
333 | void fastcall exit_aio(struct mm_struct *mm) | |
334 | { | |
335 | struct kioctx *ctx = mm->ioctx_list; | |
336 | mm->ioctx_list = NULL; | |
337 | while (ctx) { | |
338 | struct kioctx *next = ctx->next; | |
339 | ctx->next = NULL; | |
340 | aio_cancel_all(ctx); | |
341 | ||
342 | wait_for_all_aios(ctx); | |
343 | /* | |
344 | * this is an overkill, but ensures we don't leave | |
345 | * the ctx on the aio_wq | |
346 | */ | |
347 | flush_workqueue(aio_wq); | |
348 | ||
349 | if (1 != atomic_read(&ctx->users)) | |
350 | printk(KERN_DEBUG | |
351 | "exit_aio:ioctx still alive: %d %d %d\n", | |
352 | atomic_read(&ctx->users), ctx->dead, | |
353 | ctx->reqs_active); | |
354 | put_ioctx(ctx); | |
355 | ctx = next; | |
356 | } | |
357 | } | |
358 | ||
359 | /* __put_ioctx | |
360 | * Called when the last user of an aio context has gone away, | |
361 | * and the struct needs to be freed. | |
362 | */ | |
363 | void fastcall __put_ioctx(struct kioctx *ctx) | |
364 | { | |
365 | unsigned nr_events = ctx->max_reqs; | |
366 | ||
367 | if (unlikely(ctx->reqs_active)) | |
368 | BUG(); | |
369 | ||
370 | cancel_delayed_work(&ctx->wq); | |
371 | flush_workqueue(aio_wq); | |
372 | aio_free_ring(ctx); | |
373 | mmdrop(ctx->mm); | |
374 | ctx->mm = NULL; | |
375 | pr_debug("__put_ioctx: freeing %p\n", ctx); | |
376 | kmem_cache_free(kioctx_cachep, ctx); | |
377 | ||
378 | atomic_sub(nr_events, &aio_nr); | |
379 | } | |
380 | ||
381 | /* aio_get_req | |
382 | * Allocate a slot for an aio request. Increments the users count | |
383 | * of the kioctx so that the kioctx stays around until all requests are | |
384 | * complete. Returns NULL if no requests are free. | |
385 | * | |
386 | * Returns with kiocb->users set to 2. The io submit code path holds | |
387 | * an extra reference while submitting the i/o. | |
388 | * This prevents races between the aio code path referencing the | |
389 | * req (after submitting it) and aio_complete() freeing the req. | |
390 | */ | |
391 | static struct kiocb *FASTCALL(__aio_get_req(struct kioctx *ctx)); | |
392 | static struct kiocb fastcall *__aio_get_req(struct kioctx *ctx) | |
393 | { | |
394 | struct kiocb *req = NULL; | |
395 | struct aio_ring *ring; | |
396 | int okay = 0; | |
397 | ||
398 | req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL); | |
399 | if (unlikely(!req)) | |
400 | return NULL; | |
401 | ||
402 | req->ki_flags = 1 << KIF_LOCKED; | |
403 | req->ki_users = 2; | |
404 | req->ki_key = 0; | |
405 | req->ki_ctx = ctx; | |
406 | req->ki_cancel = NULL; | |
407 | req->ki_retry = NULL; | |
408 | req->ki_obj.user = NULL; | |
409 | req->ki_dtor = NULL; | |
410 | req->private = NULL; | |
411 | INIT_LIST_HEAD(&req->ki_run_list); | |
412 | ||
413 | /* Check if the completion queue has enough free space to | |
414 | * accept an event from this io. | |
415 | */ | |
416 | spin_lock_irq(&ctx->ctx_lock); | |
417 | ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0); | |
418 | if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) { | |
419 | list_add(&req->ki_list, &ctx->active_reqs); | |
420 | get_ioctx(ctx); | |
421 | ctx->reqs_active++; | |
422 | okay = 1; | |
423 | } | |
424 | kunmap_atomic(ring, KM_USER0); | |
425 | spin_unlock_irq(&ctx->ctx_lock); | |
426 | ||
427 | if (!okay) { | |
428 | kmem_cache_free(kiocb_cachep, req); | |
429 | req = NULL; | |
430 | } | |
431 | ||
432 | return req; | |
433 | } | |
434 | ||
435 | static inline struct kiocb *aio_get_req(struct kioctx *ctx) | |
436 | { | |
437 | struct kiocb *req; | |
438 | /* Handle a potential starvation case -- should be exceedingly rare as | |
439 | * requests will be stuck on fput_head only if the aio_fput_routine is | |
440 | * delayed and the requests were the last user of the struct file. | |
441 | */ | |
442 | req = __aio_get_req(ctx); | |
443 | if (unlikely(NULL == req)) { | |
444 | aio_fput_routine(NULL); | |
445 | req = __aio_get_req(ctx); | |
446 | } | |
447 | return req; | |
448 | } | |
449 | ||
450 | static inline void really_put_req(struct kioctx *ctx, struct kiocb *req) | |
451 | { | |
452 | if (req->ki_dtor) | |
453 | req->ki_dtor(req); | |
454 | req->ki_ctx = NULL; | |
455 | req->ki_filp = NULL; | |
456 | req->ki_obj.user = NULL; | |
457 | req->ki_dtor = NULL; | |
458 | req->private = NULL; | |
459 | kmem_cache_free(kiocb_cachep, req); | |
460 | ctx->reqs_active--; | |
461 | ||
462 | if (unlikely(!ctx->reqs_active && ctx->dead)) | |
463 | wake_up(&ctx->wait); | |
464 | } | |
465 | ||
466 | static void aio_fput_routine(void *data) | |
467 | { | |
468 | spin_lock_irq(&fput_lock); | |
469 | while (likely(!list_empty(&fput_head))) { | |
470 | struct kiocb *req = list_kiocb(fput_head.next); | |
471 | struct kioctx *ctx = req->ki_ctx; | |
472 | ||
473 | list_del(&req->ki_list); | |
474 | spin_unlock_irq(&fput_lock); | |
475 | ||
476 | /* Complete the fput */ | |
477 | __fput(req->ki_filp); | |
478 | ||
479 | /* Link the iocb into the context's free list */ | |
480 | spin_lock_irq(&ctx->ctx_lock); | |
481 | really_put_req(ctx, req); | |
482 | spin_unlock_irq(&ctx->ctx_lock); | |
483 | ||
484 | put_ioctx(ctx); | |
485 | spin_lock_irq(&fput_lock); | |
486 | } | |
487 | spin_unlock_irq(&fput_lock); | |
488 | } | |
489 | ||
490 | /* __aio_put_req | |
491 | * Returns true if this put was the last user of the request. | |
492 | */ | |
493 | static int __aio_put_req(struct kioctx *ctx, struct kiocb *req) | |
494 | { | |
495 | dprintk(KERN_DEBUG "aio_put(%p): f_count=%d\n", | |
496 | req, atomic_read(&req->ki_filp->f_count)); | |
497 | ||
498 | req->ki_users --; | |
499 | if (unlikely(req->ki_users < 0)) | |
500 | BUG(); | |
501 | if (likely(req->ki_users)) | |
502 | return 0; | |
503 | list_del(&req->ki_list); /* remove from active_reqs */ | |
504 | req->ki_cancel = NULL; | |
505 | req->ki_retry = NULL; | |
506 | ||
507 | /* Must be done under the lock to serialise against cancellation. | |
508 | * Call this aio_fput as it duplicates fput via the fput_work. | |
509 | */ | |
510 | if (unlikely(atomic_dec_and_test(&req->ki_filp->f_count))) { | |
511 | get_ioctx(ctx); | |
512 | spin_lock(&fput_lock); | |
513 | list_add(&req->ki_list, &fput_head); | |
514 | spin_unlock(&fput_lock); | |
515 | queue_work(aio_wq, &fput_work); | |
516 | } else | |
517 | really_put_req(ctx, req); | |
518 | return 1; | |
519 | } | |
520 | ||
521 | /* aio_put_req | |
522 | * Returns true if this put was the last user of the kiocb, | |
523 | * false if the request is still in use. | |
524 | */ | |
525 | int fastcall aio_put_req(struct kiocb *req) | |
526 | { | |
527 | struct kioctx *ctx = req->ki_ctx; | |
528 | int ret; | |
529 | spin_lock_irq(&ctx->ctx_lock); | |
530 | ret = __aio_put_req(ctx, req); | |
531 | spin_unlock_irq(&ctx->ctx_lock); | |
532 | if (ret) | |
533 | put_ioctx(ctx); | |
534 | return ret; | |
535 | } | |
536 | ||
537 | /* Lookup an ioctx id. ioctx_list is lockless for reads. | |
538 | * FIXME: this is O(n) and is only suitable for development. | |
539 | */ | |
540 | struct kioctx *lookup_ioctx(unsigned long ctx_id) | |
541 | { | |
542 | struct kioctx *ioctx; | |
543 | struct mm_struct *mm; | |
544 | ||
545 | mm = current->mm; | |
546 | read_lock(&mm->ioctx_list_lock); | |
547 | for (ioctx = mm->ioctx_list; ioctx; ioctx = ioctx->next) | |
548 | if (likely(ioctx->user_id == ctx_id && !ioctx->dead)) { | |
549 | get_ioctx(ioctx); | |
550 | break; | |
551 | } | |
552 | read_unlock(&mm->ioctx_list_lock); | |
553 | ||
554 | return ioctx; | |
555 | } | |
556 | ||
557 | /* | |
558 | * use_mm | |
559 | * Makes the calling kernel thread take on the specified | |
560 | * mm context. | |
561 | * Called by the retry thread execute retries within the | |
562 | * iocb issuer's mm context, so that copy_from/to_user | |
563 | * operations work seamlessly for aio. | |
564 | * (Note: this routine is intended to be called only | |
565 | * from a kernel thread context) | |
566 | */ | |
567 | static void use_mm(struct mm_struct *mm) | |
568 | { | |
569 | struct mm_struct *active_mm; | |
570 | struct task_struct *tsk = current; | |
571 | ||
572 | task_lock(tsk); | |
573 | tsk->flags |= PF_BORROWED_MM; | |
574 | active_mm = tsk->active_mm; | |
575 | atomic_inc(&mm->mm_count); | |
576 | tsk->mm = mm; | |
577 | tsk->active_mm = mm; | |
578 | activate_mm(active_mm, mm); | |
579 | task_unlock(tsk); | |
580 | ||
581 | mmdrop(active_mm); | |
582 | } | |
583 | ||
584 | /* | |
585 | * unuse_mm | |
586 | * Reverses the effect of use_mm, i.e. releases the | |
587 | * specified mm context which was earlier taken on | |
588 | * by the calling kernel thread | |
589 | * (Note: this routine is intended to be called only | |
590 | * from a kernel thread context) | |
591 | * | |
592 | * Comments: Called with ctx->ctx_lock held. This nests | |
593 | * task_lock instead ctx_lock. | |
594 | */ | |
595 | void unuse_mm(struct mm_struct *mm) | |
596 | { | |
597 | struct task_struct *tsk = current; | |
598 | ||
599 | task_lock(tsk); | |
600 | tsk->flags &= ~PF_BORROWED_MM; | |
601 | tsk->mm = NULL; | |
602 | /* active_mm is still 'mm' */ | |
603 | enter_lazy_tlb(mm, tsk); | |
604 | task_unlock(tsk); | |
605 | } | |
606 | ||
607 | /* | |
608 | * Queue up a kiocb to be retried. Assumes that the kiocb | |
609 | * has already been marked as kicked, and places it on | |
610 | * the retry run list for the corresponding ioctx, if it | |
611 | * isn't already queued. Returns 1 if it actually queued | |
612 | * the kiocb (to tell the caller to activate the work | |
613 | * queue to process it), or 0, if it found that it was | |
614 | * already queued. | |
615 | * | |
616 | * Should be called with the spin lock iocb->ki_ctx->ctx_lock | |
617 | * held | |
618 | */ | |
619 | static inline int __queue_kicked_iocb(struct kiocb *iocb) | |
620 | { | |
621 | struct kioctx *ctx = iocb->ki_ctx; | |
622 | ||
623 | if (list_empty(&iocb->ki_run_list)) { | |
624 | list_add_tail(&iocb->ki_run_list, | |
625 | &ctx->run_list); | |
626 | iocb->ki_queued++; | |
627 | return 1; | |
628 | } | |
629 | return 0; | |
630 | } | |
631 | ||
632 | /* aio_run_iocb | |
633 | * This is the core aio execution routine. It is | |
634 | * invoked both for initial i/o submission and | |
635 | * subsequent retries via the aio_kick_handler. | |
636 | * Expects to be invoked with iocb->ki_ctx->lock | |
637 | * already held. The lock is released and reaquired | |
638 | * as needed during processing. | |
639 | * | |
640 | * Calls the iocb retry method (already setup for the | |
641 | * iocb on initial submission) for operation specific | |
642 | * handling, but takes care of most of common retry | |
643 | * execution details for a given iocb. The retry method | |
644 | * needs to be non-blocking as far as possible, to avoid | |
645 | * holding up other iocbs waiting to be serviced by the | |
646 | * retry kernel thread. | |
647 | * | |
648 | * The trickier parts in this code have to do with | |
649 | * ensuring that only one retry instance is in progress | |
650 | * for a given iocb at any time. Providing that guarantee | |
651 | * simplifies the coding of individual aio operations as | |
652 | * it avoids various potential races. | |
653 | */ | |
654 | static ssize_t aio_run_iocb(struct kiocb *iocb) | |
655 | { | |
656 | struct kioctx *ctx = iocb->ki_ctx; | |
657 | ssize_t (*retry)(struct kiocb *); | |
658 | ssize_t ret; | |
659 | ||
660 | if (iocb->ki_retried++ > 1024*1024) { | |
661 | printk("Maximal retry count. Bytes done %Zd\n", | |
662 | iocb->ki_nbytes - iocb->ki_left); | |
663 | return -EAGAIN; | |
664 | } | |
665 | ||
666 | if (!(iocb->ki_retried & 0xff)) { | |
667 | pr_debug("%ld retry: %d of %d (kick %ld, Q %ld run %ld, wake %ld)\n", | |
668 | iocb->ki_retried, | |
669 | iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes, | |
670 | iocb->ki_kicked, iocb->ki_queued, aio_run, aio_wakeups); | |
671 | } | |
672 | ||
673 | if (!(retry = iocb->ki_retry)) { | |
674 | printk("aio_run_iocb: iocb->ki_retry = NULL\n"); | |
675 | return 0; | |
676 | } | |
677 | ||
678 | /* | |
679 | * We don't want the next retry iteration for this | |
680 | * operation to start until this one has returned and | |
681 | * updated the iocb state. However, wait_queue functions | |
682 | * can trigger a kick_iocb from interrupt context in the | |
683 | * meantime, indicating that data is available for the next | |
684 | * iteration. We want to remember that and enable the | |
685 | * next retry iteration _after_ we are through with | |
686 | * this one. | |
687 | * | |
688 | * So, in order to be able to register a "kick", but | |
689 | * prevent it from being queued now, we clear the kick | |
690 | * flag, but make the kick code *think* that the iocb is | |
691 | * still on the run list until we are actually done. | |
692 | * When we are done with this iteration, we check if | |
693 | * the iocb was kicked in the meantime and if so, queue | |
694 | * it up afresh. | |
695 | */ | |
696 | ||
697 | kiocbClearKicked(iocb); | |
698 | ||
699 | /* | |
700 | * This is so that aio_complete knows it doesn't need to | |
701 | * pull the iocb off the run list (We can't just call | |
702 | * INIT_LIST_HEAD because we don't want a kick_iocb to | |
703 | * queue this on the run list yet) | |
704 | */ | |
705 | iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL; | |
706 | spin_unlock_irq(&ctx->ctx_lock); | |
707 | ||
708 | /* Quit retrying if the i/o has been cancelled */ | |
709 | if (kiocbIsCancelled(iocb)) { | |
710 | ret = -EINTR; | |
711 | aio_complete(iocb, ret, 0); | |
712 | /* must not access the iocb after this */ | |
713 | goto out; | |
714 | } | |
715 | ||
716 | /* | |
717 | * Now we are all set to call the retry method in async | |
718 | * context. By setting this thread's io_wait context | |
719 | * to point to the wait queue entry inside the currently | |
720 | * running iocb for the duration of the retry, we ensure | |
721 | * that async notification wakeups are queued by the | |
722 | * operation instead of blocking waits, and when notified, | |
723 | * cause the iocb to be kicked for continuation (through | |
724 | * the aio_wake_function callback). | |
725 | */ | |
726 | BUG_ON(current->io_wait != NULL); | |
727 | current->io_wait = &iocb->ki_wait; | |
728 | ret = retry(iocb); | |
729 | current->io_wait = NULL; | |
730 | ||
731 | if (-EIOCBRETRY != ret) { | |
732 | if (-EIOCBQUEUED != ret) { | |
733 | BUG_ON(!list_empty(&iocb->ki_wait.task_list)); | |
734 | aio_complete(iocb, ret, 0); | |
735 | /* must not access the iocb after this */ | |
736 | } | |
737 | } else { | |
738 | /* | |
739 | * Issue an additional retry to avoid waiting forever if | |
740 | * no waits were queued (e.g. in case of a short read). | |
741 | */ | |
742 | if (list_empty(&iocb->ki_wait.task_list)) | |
743 | kiocbSetKicked(iocb); | |
744 | } | |
745 | out: | |
746 | spin_lock_irq(&ctx->ctx_lock); | |
747 | ||
748 | if (-EIOCBRETRY == ret) { | |
749 | /* | |
750 | * OK, now that we are done with this iteration | |
751 | * and know that there is more left to go, | |
752 | * this is where we let go so that a subsequent | |
753 | * "kick" can start the next iteration | |
754 | */ | |
755 | ||
756 | /* will make __queue_kicked_iocb succeed from here on */ | |
757 | INIT_LIST_HEAD(&iocb->ki_run_list); | |
758 | /* we must queue the next iteration ourselves, if it | |
759 | * has already been kicked */ | |
760 | if (kiocbIsKicked(iocb)) { | |
761 | __queue_kicked_iocb(iocb); | |
762 | } | |
763 | } | |
764 | return ret; | |
765 | } | |
766 | ||
767 | /* | |
768 | * __aio_run_iocbs: | |
769 | * Process all pending retries queued on the ioctx | |
770 | * run list. | |
771 | * Assumes it is operating within the aio issuer's mm | |
772 | * context. Expects to be called with ctx->ctx_lock held | |
773 | */ | |
774 | static int __aio_run_iocbs(struct kioctx *ctx) | |
775 | { | |
776 | struct kiocb *iocb; | |
777 | int count = 0; | |
778 | LIST_HEAD(run_list); | |
779 | ||
780 | list_splice_init(&ctx->run_list, &run_list); | |
781 | while (!list_empty(&run_list)) { | |
782 | iocb = list_entry(run_list.next, struct kiocb, | |
783 | ki_run_list); | |
784 | list_del(&iocb->ki_run_list); | |
785 | /* | |
786 | * Hold an extra reference while retrying i/o. | |
787 | */ | |
788 | iocb->ki_users++; /* grab extra reference */ | |
789 | aio_run_iocb(iocb); | |
790 | if (__aio_put_req(ctx, iocb)) /* drop extra ref */ | |
791 | put_ioctx(ctx); | |
792 | count++; | |
793 | } | |
794 | aio_run++; | |
795 | if (!list_empty(&ctx->run_list)) | |
796 | return 1; | |
797 | return 0; | |
798 | } | |
799 | ||
800 | static void aio_queue_work(struct kioctx * ctx) | |
801 | { | |
802 | unsigned long timeout; | |
803 | /* | |
804 | * if someone is waiting, get the work started right | |
805 | * away, otherwise, use a longer delay | |
806 | */ | |
807 | smp_mb(); | |
808 | if (waitqueue_active(&ctx->wait)) | |
809 | timeout = 1; | |
810 | else | |
811 | timeout = HZ/10; | |
812 | queue_delayed_work(aio_wq, &ctx->wq, timeout); | |
813 | } | |
814 | ||
815 | ||
816 | /* | |
817 | * aio_run_iocbs: | |
818 | * Process all pending retries queued on the ioctx | |
819 | * run list. | |
820 | * Assumes it is operating within the aio issuer's mm | |
821 | * context. | |
822 | */ | |
823 | static inline void aio_run_iocbs(struct kioctx *ctx) | |
824 | { | |
825 | int requeue; | |
826 | ||
827 | spin_lock_irq(&ctx->ctx_lock); | |
828 | ||
829 | requeue = __aio_run_iocbs(ctx); | |
830 | spin_unlock_irq(&ctx->ctx_lock); | |
831 | if (requeue) | |
832 | aio_queue_work(ctx); | |
833 | } | |
834 | ||
835 | /* | |
836 | * just like aio_run_iocbs, but keeps running them until | |
837 | * the list stays empty | |
838 | */ | |
839 | static inline void aio_run_all_iocbs(struct kioctx *ctx) | |
840 | { | |
841 | spin_lock_irq(&ctx->ctx_lock); | |
842 | while (__aio_run_iocbs(ctx)) | |
843 | ; | |
844 | spin_unlock_irq(&ctx->ctx_lock); | |
845 | } | |
846 | ||
847 | /* | |
848 | * aio_kick_handler: | |
849 | * Work queue handler triggered to process pending | |
850 | * retries on an ioctx. Takes on the aio issuer's | |
851 | * mm context before running the iocbs, so that | |
852 | * copy_xxx_user operates on the issuer's address | |
853 | * space. | |
854 | * Run on aiod's context. | |
855 | */ | |
856 | static void aio_kick_handler(void *data) | |
857 | { | |
858 | struct kioctx *ctx = data; | |
859 | mm_segment_t oldfs = get_fs(); | |
860 | int requeue; | |
861 | ||
862 | set_fs(USER_DS); | |
863 | use_mm(ctx->mm); | |
864 | spin_lock_irq(&ctx->ctx_lock); | |
865 | requeue =__aio_run_iocbs(ctx); | |
866 | unuse_mm(ctx->mm); | |
867 | spin_unlock_irq(&ctx->ctx_lock); | |
868 | set_fs(oldfs); | |
869 | /* | |
870 | * we're in a worker thread already, don't use queue_delayed_work, | |
871 | */ | |
872 | if (requeue) | |
873 | queue_work(aio_wq, &ctx->wq); | |
874 | } | |
875 | ||
876 | ||
877 | /* | |
878 | * Called by kick_iocb to queue the kiocb for retry | |
879 | * and if required activate the aio work queue to process | |
880 | * it | |
881 | */ | |
882 | void queue_kicked_iocb(struct kiocb *iocb) | |
883 | { | |
884 | struct kioctx *ctx = iocb->ki_ctx; | |
885 | unsigned long flags; | |
886 | int run = 0; | |
887 | ||
888 | WARN_ON((!list_empty(&iocb->ki_wait.task_list))); | |
889 | ||
890 | spin_lock_irqsave(&ctx->ctx_lock, flags); | |
891 | run = __queue_kicked_iocb(iocb); | |
892 | spin_unlock_irqrestore(&ctx->ctx_lock, flags); | |
893 | if (run) { | |
894 | aio_queue_work(ctx); | |
895 | aio_wakeups++; | |
896 | } | |
897 | } | |
898 | ||
899 | /* | |
900 | * kick_iocb: | |
901 | * Called typically from a wait queue callback context | |
902 | * (aio_wake_function) to trigger a retry of the iocb. | |
903 | * The retry is usually executed by aio workqueue | |
904 | * threads (See aio_kick_handler). | |
905 | */ | |
906 | void fastcall kick_iocb(struct kiocb *iocb) | |
907 | { | |
908 | /* sync iocbs are easy: they can only ever be executing from a | |
909 | * single context. */ | |
910 | if (is_sync_kiocb(iocb)) { | |
911 | kiocbSetKicked(iocb); | |
912 | wake_up_process(iocb->ki_obj.tsk); | |
913 | return; | |
914 | } | |
915 | ||
916 | iocb->ki_kicked++; | |
917 | /* If its already kicked we shouldn't queue it again */ | |
918 | if (!kiocbTryKick(iocb)) { | |
919 | queue_kicked_iocb(iocb); | |
920 | } | |
921 | } | |
922 | EXPORT_SYMBOL(kick_iocb); | |
923 | ||
924 | /* aio_complete | |
925 | * Called when the io request on the given iocb is complete. | |
926 | * Returns true if this is the last user of the request. The | |
927 | * only other user of the request can be the cancellation code. | |
928 | */ | |
929 | int fastcall aio_complete(struct kiocb *iocb, long res, long res2) | |
930 | { | |
931 | struct kioctx *ctx = iocb->ki_ctx; | |
932 | struct aio_ring_info *info; | |
933 | struct aio_ring *ring; | |
934 | struct io_event *event; | |
935 | unsigned long flags; | |
936 | unsigned long tail; | |
937 | int ret; | |
938 | ||
939 | /* Special case handling for sync iocbs: events go directly | |
940 | * into the iocb for fast handling. Note that this will not | |
941 | * work if we allow sync kiocbs to be cancelled. in which | |
942 | * case the usage count checks will have to move under ctx_lock | |
943 | * for all cases. | |
944 | */ | |
945 | if (is_sync_kiocb(iocb)) { | |
946 | int ret; | |
947 | ||
948 | iocb->ki_user_data = res; | |
949 | if (iocb->ki_users == 1) { | |
950 | iocb->ki_users = 0; | |
951 | ret = 1; | |
952 | } else { | |
953 | spin_lock_irq(&ctx->ctx_lock); | |
954 | iocb->ki_users--; | |
955 | ret = (0 == iocb->ki_users); | |
956 | spin_unlock_irq(&ctx->ctx_lock); | |
957 | } | |
958 | /* sync iocbs put the task here for us */ | |
959 | wake_up_process(iocb->ki_obj.tsk); | |
960 | return ret; | |
961 | } | |
962 | ||
963 | info = &ctx->ring_info; | |
964 | ||
965 | /* add a completion event to the ring buffer. | |
966 | * must be done holding ctx->ctx_lock to prevent | |
967 | * other code from messing with the tail | |
968 | * pointer since we might be called from irq | |
969 | * context. | |
970 | */ | |
971 | spin_lock_irqsave(&ctx->ctx_lock, flags); | |
972 | ||
973 | if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list)) | |
974 | list_del_init(&iocb->ki_run_list); | |
975 | ||
976 | /* | |
977 | * cancelled requests don't get events, userland was given one | |
978 | * when the event got cancelled. | |
979 | */ | |
980 | if (kiocbIsCancelled(iocb)) | |
981 | goto put_rq; | |
982 | ||
983 | ring = kmap_atomic(info->ring_pages[0], KM_IRQ1); | |
984 | ||
985 | tail = info->tail; | |
986 | event = aio_ring_event(info, tail, KM_IRQ0); | |
987 | tail = (tail + 1) % info->nr; | |
988 | ||
989 | event->obj = (u64)(unsigned long)iocb->ki_obj.user; | |
990 | event->data = iocb->ki_user_data; | |
991 | event->res = res; | |
992 | event->res2 = res2; | |
993 | ||
994 | dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n", | |
995 | ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data, | |
996 | res, res2); | |
997 | ||
998 | /* after flagging the request as done, we | |
999 | * must never even look at it again | |
1000 | */ | |
1001 | smp_wmb(); /* make event visible before updating tail */ | |
1002 | ||
1003 | info->tail = tail; | |
1004 | ring->tail = tail; | |
1005 | ||
1006 | put_aio_ring_event(event, KM_IRQ0); | |
1007 | kunmap_atomic(ring, KM_IRQ1); | |
1008 | ||
1009 | pr_debug("added to ring %p at [%lu]\n", iocb, tail); | |
1010 | ||
1011 | pr_debug("%ld retries: %d of %d (kicked %ld, Q %ld run %ld wake %ld)\n", | |
1012 | iocb->ki_retried, | |
1013 | iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes, | |
1014 | iocb->ki_kicked, iocb->ki_queued, aio_run, aio_wakeups); | |
1015 | put_rq: | |
1016 | /* everything turned out well, dispose of the aiocb. */ | |
1017 | ret = __aio_put_req(ctx, iocb); | |
1018 | ||
1019 | spin_unlock_irqrestore(&ctx->ctx_lock, flags); | |
1020 | ||
1021 | if (waitqueue_active(&ctx->wait)) | |
1022 | wake_up(&ctx->wait); | |
1023 | ||
1024 | if (ret) | |
1025 | put_ioctx(ctx); | |
1026 | ||
1027 | return ret; | |
1028 | } | |
1029 | ||
1030 | /* aio_read_evt | |
1031 | * Pull an event off of the ioctx's event ring. Returns the number of | |
1032 | * events fetched (0 or 1 ;-) | |
1033 | * FIXME: make this use cmpxchg. | |
1034 | * TODO: make the ringbuffer user mmap()able (requires FIXME). | |
1035 | */ | |
1036 | static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent) | |
1037 | { | |
1038 | struct aio_ring_info *info = &ioctx->ring_info; | |
1039 | struct aio_ring *ring; | |
1040 | unsigned long head; | |
1041 | int ret = 0; | |
1042 | ||
1043 | ring = kmap_atomic(info->ring_pages[0], KM_USER0); | |
1044 | dprintk("in aio_read_evt h%lu t%lu m%lu\n", | |
1045 | (unsigned long)ring->head, (unsigned long)ring->tail, | |
1046 | (unsigned long)ring->nr); | |
1047 | ||
1048 | if (ring->head == ring->tail) | |
1049 | goto out; | |
1050 | ||
1051 | spin_lock(&info->ring_lock); | |
1052 | ||
1053 | head = ring->head % info->nr; | |
1054 | if (head != ring->tail) { | |
1055 | struct io_event *evp = aio_ring_event(info, head, KM_USER1); | |
1056 | *ent = *evp; | |
1057 | head = (head + 1) % info->nr; | |
1058 | smp_mb(); /* finish reading the event before updatng the head */ | |
1059 | ring->head = head; | |
1060 | ret = 1; | |
1061 | put_aio_ring_event(evp, KM_USER1); | |
1062 | } | |
1063 | spin_unlock(&info->ring_lock); | |
1064 | ||
1065 | out: | |
1066 | kunmap_atomic(ring, KM_USER0); | |
1067 | dprintk("leaving aio_read_evt: %d h%lu t%lu\n", ret, | |
1068 | (unsigned long)ring->head, (unsigned long)ring->tail); | |
1069 | return ret; | |
1070 | } | |
1071 | ||
1072 | struct aio_timeout { | |
1073 | struct timer_list timer; | |
1074 | int timed_out; | |
1075 | struct task_struct *p; | |
1076 | }; | |
1077 | ||
1078 | static void timeout_func(unsigned long data) | |
1079 | { | |
1080 | struct aio_timeout *to = (struct aio_timeout *)data; | |
1081 | ||
1082 | to->timed_out = 1; | |
1083 | wake_up_process(to->p); | |
1084 | } | |
1085 | ||
1086 | static inline void init_timeout(struct aio_timeout *to) | |
1087 | { | |
1088 | init_timer(&to->timer); | |
1089 | to->timer.data = (unsigned long)to; | |
1090 | to->timer.function = timeout_func; | |
1091 | to->timed_out = 0; | |
1092 | to->p = current; | |
1093 | } | |
1094 | ||
1095 | static inline void set_timeout(long start_jiffies, struct aio_timeout *to, | |
1096 | const struct timespec *ts) | |
1097 | { | |
1098 | to->timer.expires = start_jiffies + timespec_to_jiffies(ts); | |
1099 | if (time_after(to->timer.expires, jiffies)) | |
1100 | add_timer(&to->timer); | |
1101 | else | |
1102 | to->timed_out = 1; | |
1103 | } | |
1104 | ||
1105 | static inline void clear_timeout(struct aio_timeout *to) | |
1106 | { | |
1107 | del_singleshot_timer_sync(&to->timer); | |
1108 | } | |
1109 | ||
1110 | static int read_events(struct kioctx *ctx, | |
1111 | long min_nr, long nr, | |
1112 | struct io_event __user *event, | |
1113 | struct timespec __user *timeout) | |
1114 | { | |
1115 | long start_jiffies = jiffies; | |
1116 | struct task_struct *tsk = current; | |
1117 | DECLARE_WAITQUEUE(wait, tsk); | |
1118 | int ret; | |
1119 | int i = 0; | |
1120 | struct io_event ent; | |
1121 | struct aio_timeout to; | |
1122 | int event_loop = 0; /* testing only */ | |
1123 | int retry = 0; | |
1124 | ||
1125 | /* needed to zero any padding within an entry (there shouldn't be | |
1126 | * any, but C is fun! | |
1127 | */ | |
1128 | memset(&ent, 0, sizeof(ent)); | |
1129 | retry: | |
1130 | ret = 0; | |
1131 | while (likely(i < nr)) { | |
1132 | ret = aio_read_evt(ctx, &ent); | |
1133 | if (unlikely(ret <= 0)) | |
1134 | break; | |
1135 | ||
1136 | dprintk("read event: %Lx %Lx %Lx %Lx\n", | |
1137 | ent.data, ent.obj, ent.res, ent.res2); | |
1138 | ||
1139 | /* Could we split the check in two? */ | |
1140 | ret = -EFAULT; | |
1141 | if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { | |
1142 | dprintk("aio: lost an event due to EFAULT.\n"); | |
1143 | break; | |
1144 | } | |
1145 | ret = 0; | |
1146 | ||
1147 | /* Good, event copied to userland, update counts. */ | |
1148 | event ++; | |
1149 | i ++; | |
1150 | } | |
1151 | ||
1152 | if (min_nr <= i) | |
1153 | return i; | |
1154 | if (ret) | |
1155 | return ret; | |
1156 | ||
1157 | /* End fast path */ | |
1158 | ||
1159 | /* racey check, but it gets redone */ | |
1160 | if (!retry && unlikely(!list_empty(&ctx->run_list))) { | |
1161 | retry = 1; | |
1162 | aio_run_all_iocbs(ctx); | |
1163 | goto retry; | |
1164 | } | |
1165 | ||
1166 | init_timeout(&to); | |
1167 | if (timeout) { | |
1168 | struct timespec ts; | |
1169 | ret = -EFAULT; | |
1170 | if (unlikely(copy_from_user(&ts, timeout, sizeof(ts)))) | |
1171 | goto out; | |
1172 | ||
1173 | set_timeout(start_jiffies, &to, &ts); | |
1174 | } | |
1175 | ||
1176 | while (likely(i < nr)) { | |
1177 | add_wait_queue_exclusive(&ctx->wait, &wait); | |
1178 | do { | |
1179 | set_task_state(tsk, TASK_INTERRUPTIBLE); | |
1180 | ret = aio_read_evt(ctx, &ent); | |
1181 | if (ret) | |
1182 | break; | |
1183 | if (min_nr <= i) | |
1184 | break; | |
1185 | ret = 0; | |
1186 | if (to.timed_out) /* Only check after read evt */ | |
1187 | break; | |
1188 | schedule(); | |
1189 | event_loop++; | |
1190 | if (signal_pending(tsk)) { | |
1191 | ret = -EINTR; | |
1192 | break; | |
1193 | } | |
1194 | /*ret = aio_read_evt(ctx, &ent);*/ | |
1195 | } while (1) ; | |
1196 | ||
1197 | set_task_state(tsk, TASK_RUNNING); | |
1198 | remove_wait_queue(&ctx->wait, &wait); | |
1199 | ||
1200 | if (unlikely(ret <= 0)) | |
1201 | break; | |
1202 | ||
1203 | ret = -EFAULT; | |
1204 | if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { | |
1205 | dprintk("aio: lost an event due to EFAULT.\n"); | |
1206 | break; | |
1207 | } | |
1208 | ||
1209 | /* Good, event copied to userland, update counts. */ | |
1210 | event ++; | |
1211 | i ++; | |
1212 | } | |
1213 | ||
1214 | if (timeout) | |
1215 | clear_timeout(&to); | |
1216 | out: | |
1217 | pr_debug("event loop executed %d times\n", event_loop); | |
1218 | pr_debug("aio_run %ld\n", aio_run); | |
1219 | pr_debug("aio_wakeups %ld\n", aio_wakeups); | |
1220 | return i ? i : ret; | |
1221 | } | |
1222 | ||
1223 | /* Take an ioctx and remove it from the list of ioctx's. Protects | |
1224 | * against races with itself via ->dead. | |
1225 | */ | |
1226 | static void io_destroy(struct kioctx *ioctx) | |
1227 | { | |
1228 | struct mm_struct *mm = current->mm; | |
1229 | struct kioctx **tmp; | |
1230 | int was_dead; | |
1231 | ||
1232 | /* delete the entry from the list is someone else hasn't already */ | |
1233 | write_lock(&mm->ioctx_list_lock); | |
1234 | was_dead = ioctx->dead; | |
1235 | ioctx->dead = 1; | |
1236 | for (tmp = &mm->ioctx_list; *tmp && *tmp != ioctx; | |
1237 | tmp = &(*tmp)->next) | |
1238 | ; | |
1239 | if (*tmp) | |
1240 | *tmp = ioctx->next; | |
1241 | write_unlock(&mm->ioctx_list_lock); | |
1242 | ||
1243 | dprintk("aio_release(%p)\n", ioctx); | |
1244 | if (likely(!was_dead)) | |
1245 | put_ioctx(ioctx); /* twice for the list */ | |
1246 | ||
1247 | aio_cancel_all(ioctx); | |
1248 | wait_for_all_aios(ioctx); | |
1249 | put_ioctx(ioctx); /* once for the lookup */ | |
1250 | } | |
1251 | ||
1252 | /* sys_io_setup: | |
1253 | * Create an aio_context capable of receiving at least nr_events. | |
1254 | * ctxp must not point to an aio_context that already exists, and | |
1255 | * must be initialized to 0 prior to the call. On successful | |
1256 | * creation of the aio_context, *ctxp is filled in with the resulting | |
1257 | * handle. May fail with -EINVAL if *ctxp is not initialized, | |
1258 | * if the specified nr_events exceeds internal limits. May fail | |
1259 | * with -EAGAIN if the specified nr_events exceeds the user's limit | |
1260 | * of available events. May fail with -ENOMEM if insufficient kernel | |
1261 | * resources are available. May fail with -EFAULT if an invalid | |
1262 | * pointer is passed for ctxp. Will fail with -ENOSYS if not | |
1263 | * implemented. | |
1264 | */ | |
1265 | asmlinkage long sys_io_setup(unsigned nr_events, aio_context_t __user *ctxp) | |
1266 | { | |
1267 | struct kioctx *ioctx = NULL; | |
1268 | unsigned long ctx; | |
1269 | long ret; | |
1270 | ||
1271 | ret = get_user(ctx, ctxp); | |
1272 | if (unlikely(ret)) | |
1273 | goto out; | |
1274 | ||
1275 | ret = -EINVAL; | |
1276 | if (unlikely(ctx || (int)nr_events <= 0)) { | |
1277 | pr_debug("EINVAL: io_setup: ctx or nr_events > max\n"); | |
1278 | goto out; | |
1279 | } | |
1280 | ||
1281 | ioctx = ioctx_alloc(nr_events); | |
1282 | ret = PTR_ERR(ioctx); | |
1283 | if (!IS_ERR(ioctx)) { | |
1284 | ret = put_user(ioctx->user_id, ctxp); | |
1285 | if (!ret) | |
1286 | return 0; | |
1287 | ||
1288 | get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */ | |
1289 | io_destroy(ioctx); | |
1290 | } | |
1291 | ||
1292 | out: | |
1293 | return ret; | |
1294 | } | |
1295 | ||
1296 | /* sys_io_destroy: | |
1297 | * Destroy the aio_context specified. May cancel any outstanding | |
1298 | * AIOs and block on completion. Will fail with -ENOSYS if not | |
1299 | * implemented. May fail with -EFAULT if the context pointed to | |
1300 | * is invalid. | |
1301 | */ | |
1302 | asmlinkage long sys_io_destroy(aio_context_t ctx) | |
1303 | { | |
1304 | struct kioctx *ioctx = lookup_ioctx(ctx); | |
1305 | if (likely(NULL != ioctx)) { | |
1306 | io_destroy(ioctx); | |
1307 | return 0; | |
1308 | } | |
1309 | pr_debug("EINVAL: io_destroy: invalid context id\n"); | |
1310 | return -EINVAL; | |
1311 | } | |
1312 | ||
1313 | /* | |
1314 | * Default retry method for aio_read (also used for first time submit) | |
1315 | * Responsible for updating iocb state as retries progress | |
1316 | */ | |
1317 | static ssize_t aio_pread(struct kiocb *iocb) | |
1318 | { | |
1319 | struct file *file = iocb->ki_filp; | |
1320 | struct address_space *mapping = file->f_mapping; | |
1321 | struct inode *inode = mapping->host; | |
1322 | ssize_t ret = 0; | |
1323 | ||
1324 | ret = file->f_op->aio_read(iocb, iocb->ki_buf, | |
1325 | iocb->ki_left, iocb->ki_pos); | |
1326 | ||
1327 | /* | |
1328 | * Can't just depend on iocb->ki_left to determine | |
1329 | * whether we are done. This may have been a short read. | |
1330 | */ | |
1331 | if (ret > 0) { | |
1332 | iocb->ki_buf += ret; | |
1333 | iocb->ki_left -= ret; | |
1334 | /* | |
1335 | * For pipes and sockets we return once we have | |
1336 | * some data; for regular files we retry till we | |
1337 | * complete the entire read or find that we can't | |
1338 | * read any more data (e.g short reads). | |
1339 | */ | |
1340 | if (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode)) | |
1341 | ret = -EIOCBRETRY; | |
1342 | } | |
1343 | ||
1344 | /* This means we must have transferred all that we could */ | |
1345 | /* No need to retry anymore */ | |
1346 | if ((ret == 0) || (iocb->ki_left == 0)) | |
1347 | ret = iocb->ki_nbytes - iocb->ki_left; | |
1348 | ||
1349 | return ret; | |
1350 | } | |
1351 | ||
1352 | /* | |
1353 | * Default retry method for aio_write (also used for first time submit) | |
1354 | * Responsible for updating iocb state as retries progress | |
1355 | */ | |
1356 | static ssize_t aio_pwrite(struct kiocb *iocb) | |
1357 | { | |
1358 | struct file *file = iocb->ki_filp; | |
1359 | ssize_t ret = 0; | |
1360 | ||
1361 | ret = file->f_op->aio_write(iocb, iocb->ki_buf, | |
1362 | iocb->ki_left, iocb->ki_pos); | |
1363 | ||
1364 | if (ret > 0) { | |
1365 | iocb->ki_buf += ret; | |
1366 | iocb->ki_left -= ret; | |
1367 | ||
1368 | ret = -EIOCBRETRY; | |
1369 | } | |
1370 | ||
1371 | /* This means we must have transferred all that we could */ | |
1372 | /* No need to retry anymore */ | |
1373 | if ((ret == 0) || (iocb->ki_left == 0)) | |
1374 | ret = iocb->ki_nbytes - iocb->ki_left; | |
1375 | ||
1376 | return ret; | |
1377 | } | |
1378 | ||
1379 | static ssize_t aio_fdsync(struct kiocb *iocb) | |
1380 | { | |
1381 | struct file *file = iocb->ki_filp; | |
1382 | ssize_t ret = -EINVAL; | |
1383 | ||
1384 | if (file->f_op->aio_fsync) | |
1385 | ret = file->f_op->aio_fsync(iocb, 1); | |
1386 | return ret; | |
1387 | } | |
1388 | ||
1389 | static ssize_t aio_fsync(struct kiocb *iocb) | |
1390 | { | |
1391 | struct file *file = iocb->ki_filp; | |
1392 | ssize_t ret = -EINVAL; | |
1393 | ||
1394 | if (file->f_op->aio_fsync) | |
1395 | ret = file->f_op->aio_fsync(iocb, 0); | |
1396 | return ret; | |
1397 | } | |
1398 | ||
1399 | /* | |
1400 | * aio_setup_iocb: | |
1401 | * Performs the initial checks and aio retry method | |
1402 | * setup for the kiocb at the time of io submission. | |
1403 | */ | |
1404 | ssize_t aio_setup_iocb(struct kiocb *kiocb) | |
1405 | { | |
1406 | struct file *file = kiocb->ki_filp; | |
1407 | ssize_t ret = 0; | |
1408 | ||
1409 | switch (kiocb->ki_opcode) { | |
1410 | case IOCB_CMD_PREAD: | |
1411 | ret = -EBADF; | |
1412 | if (unlikely(!(file->f_mode & FMODE_READ))) | |
1413 | break; | |
1414 | ret = -EFAULT; | |
1415 | if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf, | |
1416 | kiocb->ki_left))) | |
1417 | break; | |
1418 | ret = -EINVAL; | |
1419 | if (file->f_op->aio_read) | |
1420 | kiocb->ki_retry = aio_pread; | |
1421 | break; | |
1422 | case IOCB_CMD_PWRITE: | |
1423 | ret = -EBADF; | |
1424 | if (unlikely(!(file->f_mode & FMODE_WRITE))) | |
1425 | break; | |
1426 | ret = -EFAULT; | |
1427 | if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf, | |
1428 | kiocb->ki_left))) | |
1429 | break; | |
1430 | ret = -EINVAL; | |
1431 | if (file->f_op->aio_write) | |
1432 | kiocb->ki_retry = aio_pwrite; | |
1433 | break; | |
1434 | case IOCB_CMD_FDSYNC: | |
1435 | ret = -EINVAL; | |
1436 | if (file->f_op->aio_fsync) | |
1437 | kiocb->ki_retry = aio_fdsync; | |
1438 | break; | |
1439 | case IOCB_CMD_FSYNC: | |
1440 | ret = -EINVAL; | |
1441 | if (file->f_op->aio_fsync) | |
1442 | kiocb->ki_retry = aio_fsync; | |
1443 | break; | |
1444 | default: | |
1445 | dprintk("EINVAL: io_submit: no operation provided\n"); | |
1446 | ret = -EINVAL; | |
1447 | } | |
1448 | ||
1449 | if (!kiocb->ki_retry) | |
1450 | return ret; | |
1451 | ||
1452 | return 0; | |
1453 | } | |
1454 | ||
1455 | /* | |
1456 | * aio_wake_function: | |
1457 | * wait queue callback function for aio notification, | |
1458 | * Simply triggers a retry of the operation via kick_iocb. | |
1459 | * | |
1460 | * This callback is specified in the wait queue entry in | |
1461 | * a kiocb (current->io_wait points to this wait queue | |
1462 | * entry when an aio operation executes; it is used | |
1463 | * instead of a synchronous wait when an i/o blocking | |
1464 | * condition is encountered during aio). | |
1465 | * | |
1466 | * Note: | |
1467 | * This routine is executed with the wait queue lock held. | |
1468 | * Since kick_iocb acquires iocb->ctx->ctx_lock, it nests | |
1469 | * the ioctx lock inside the wait queue lock. This is safe | |
1470 | * because this callback isn't used for wait queues which | |
1471 | * are nested inside ioctx lock (i.e. ctx->wait) | |
1472 | */ | |
1473 | int aio_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key) | |
1474 | { | |
1475 | struct kiocb *iocb = container_of(wait, struct kiocb, ki_wait); | |
1476 | ||
1477 | list_del_init(&wait->task_list); | |
1478 | kick_iocb(iocb); | |
1479 | return 1; | |
1480 | } | |
1481 | ||
1482 | int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, | |
1483 | struct iocb *iocb) | |
1484 | { | |
1485 | struct kiocb *req; | |
1486 | struct file *file; | |
1487 | ssize_t ret; | |
1488 | ||
1489 | /* enforce forwards compatibility on users */ | |
1490 | if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2 || | |
1491 | iocb->aio_reserved3)) { | |
1492 | pr_debug("EINVAL: io_submit: reserve field set\n"); | |
1493 | return -EINVAL; | |
1494 | } | |
1495 | ||
1496 | /* prevent overflows */ | |
1497 | if (unlikely( | |
1498 | (iocb->aio_buf != (unsigned long)iocb->aio_buf) || | |
1499 | (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) || | |
1500 | ((ssize_t)iocb->aio_nbytes < 0) | |
1501 | )) { | |
1502 | pr_debug("EINVAL: io_submit: overflow check\n"); | |
1503 | return -EINVAL; | |
1504 | } | |
1505 | ||
1506 | file = fget(iocb->aio_fildes); | |
1507 | if (unlikely(!file)) | |
1508 | return -EBADF; | |
1509 | ||
1510 | req = aio_get_req(ctx); /* returns with 2 references to req */ | |
1511 | if (unlikely(!req)) { | |
1512 | fput(file); | |
1513 | return -EAGAIN; | |
1514 | } | |
1515 | ||
1516 | req->ki_filp = file; | |
1517 | iocb->aio_key = req->ki_key; | |
1518 | ret = put_user(iocb->aio_key, &user_iocb->aio_key); | |
1519 | if (unlikely(ret)) { | |
1520 | dprintk("EFAULT: aio_key\n"); | |
1521 | goto out_put_req; | |
1522 | } | |
1523 | ||
1524 | req->ki_obj.user = user_iocb; | |
1525 | req->ki_user_data = iocb->aio_data; | |
1526 | req->ki_pos = iocb->aio_offset; | |
1527 | ||
1528 | req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf; | |
1529 | req->ki_left = req->ki_nbytes = iocb->aio_nbytes; | |
1530 | req->ki_opcode = iocb->aio_lio_opcode; | |
1531 | init_waitqueue_func_entry(&req->ki_wait, aio_wake_function); | |
1532 | INIT_LIST_HEAD(&req->ki_wait.task_list); | |
1533 | req->ki_run_list.next = req->ki_run_list.prev = NULL; | |
1534 | req->ki_retry = NULL; | |
1535 | req->ki_retried = 0; | |
1536 | req->ki_kicked = 0; | |
1537 | req->ki_queued = 0; | |
1538 | aio_run = 0; | |
1539 | aio_wakeups = 0; | |
1540 | ||
1541 | ret = aio_setup_iocb(req); | |
1542 | ||
1543 | if (ret) | |
1544 | goto out_put_req; | |
1545 | ||
1546 | spin_lock_irq(&ctx->ctx_lock); | |
1547 | list_add_tail(&req->ki_run_list, &ctx->run_list); | |
1548 | /* drain the run list */ | |
1549 | while (__aio_run_iocbs(ctx)) | |
1550 | ; | |
1551 | spin_unlock_irq(&ctx->ctx_lock); | |
1552 | aio_put_req(req); /* drop extra ref to req */ | |
1553 | return 0; | |
1554 | ||
1555 | out_put_req: | |
1556 | aio_put_req(req); /* drop extra ref to req */ | |
1557 | aio_put_req(req); /* drop i/o ref to req */ | |
1558 | return ret; | |
1559 | } | |
1560 | ||
1561 | /* sys_io_submit: | |
1562 | * Queue the nr iocbs pointed to by iocbpp for processing. Returns | |
1563 | * the number of iocbs queued. May return -EINVAL if the aio_context | |
1564 | * specified by ctx_id is invalid, if nr is < 0, if the iocb at | |
1565 | * *iocbpp[0] is not properly initialized, if the operation specified | |
1566 | * is invalid for the file descriptor in the iocb. May fail with | |
1567 | * -EFAULT if any of the data structures point to invalid data. May | |
1568 | * fail with -EBADF if the file descriptor specified in the first | |
1569 | * iocb is invalid. May fail with -EAGAIN if insufficient resources | |
1570 | * are available to queue any iocbs. Will return 0 if nr is 0. Will | |
1571 | * fail with -ENOSYS if not implemented. | |
1572 | */ | |
1573 | asmlinkage long sys_io_submit(aio_context_t ctx_id, long nr, | |
1574 | struct iocb __user * __user *iocbpp) | |
1575 | { | |
1576 | struct kioctx *ctx; | |
1577 | long ret = 0; | |
1578 | int i; | |
1579 | ||
1580 | if (unlikely(nr < 0)) | |
1581 | return -EINVAL; | |
1582 | ||
1583 | if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp))))) | |
1584 | return -EFAULT; | |
1585 | ||
1586 | ctx = lookup_ioctx(ctx_id); | |
1587 | if (unlikely(!ctx)) { | |
1588 | pr_debug("EINVAL: io_submit: invalid context id\n"); | |
1589 | return -EINVAL; | |
1590 | } | |
1591 | ||
1592 | /* | |
1593 | * AKPM: should this return a partial result if some of the IOs were | |
1594 | * successfully submitted? | |
1595 | */ | |
1596 | for (i=0; i<nr; i++) { | |
1597 | struct iocb __user *user_iocb; | |
1598 | struct iocb tmp; | |
1599 | ||
1600 | if (unlikely(__get_user(user_iocb, iocbpp + i))) { | |
1601 | ret = -EFAULT; | |
1602 | break; | |
1603 | } | |
1604 | ||
1605 | if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) { | |
1606 | ret = -EFAULT; | |
1607 | break; | |
1608 | } | |
1609 | ||
1610 | ret = io_submit_one(ctx, user_iocb, &tmp); | |
1611 | if (ret) | |
1612 | break; | |
1613 | } | |
1614 | ||
1615 | put_ioctx(ctx); | |
1616 | return i ? i : ret; | |
1617 | } | |
1618 | ||
1619 | /* lookup_kiocb | |
1620 | * Finds a given iocb for cancellation. | |
1621 | * MUST be called with ctx->ctx_lock held. | |
1622 | */ | |
1623 | struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, u32 key) | |
1624 | { | |
1625 | struct list_head *pos; | |
1626 | /* TODO: use a hash or array, this sucks. */ | |
1627 | list_for_each(pos, &ctx->active_reqs) { | |
1628 | struct kiocb *kiocb = list_kiocb(pos); | |
1629 | if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key) | |
1630 | return kiocb; | |
1631 | } | |
1632 | return NULL; | |
1633 | } | |
1634 | ||
1635 | /* sys_io_cancel: | |
1636 | * Attempts to cancel an iocb previously passed to io_submit. If | |
1637 | * the operation is successfully cancelled, the resulting event is | |
1638 | * copied into the memory pointed to by result without being placed | |
1639 | * into the completion queue and 0 is returned. May fail with | |
1640 | * -EFAULT if any of the data structures pointed to are invalid. | |
1641 | * May fail with -EINVAL if aio_context specified by ctx_id is | |
1642 | * invalid. May fail with -EAGAIN if the iocb specified was not | |
1643 | * cancelled. Will fail with -ENOSYS if not implemented. | |
1644 | */ | |
1645 | asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb, | |
1646 | struct io_event __user *result) | |
1647 | { | |
1648 | int (*cancel)(struct kiocb *iocb, struct io_event *res); | |
1649 | struct kioctx *ctx; | |
1650 | struct kiocb *kiocb; | |
1651 | u32 key; | |
1652 | int ret; | |
1653 | ||
1654 | ret = get_user(key, &iocb->aio_key); | |
1655 | if (unlikely(ret)) | |
1656 | return -EFAULT; | |
1657 | ||
1658 | ctx = lookup_ioctx(ctx_id); | |
1659 | if (unlikely(!ctx)) | |
1660 | return -EINVAL; | |
1661 | ||
1662 | spin_lock_irq(&ctx->ctx_lock); | |
1663 | ret = -EAGAIN; | |
1664 | kiocb = lookup_kiocb(ctx, iocb, key); | |
1665 | if (kiocb && kiocb->ki_cancel) { | |
1666 | cancel = kiocb->ki_cancel; | |
1667 | kiocb->ki_users ++; | |
1668 | kiocbSetCancelled(kiocb); | |
1669 | } else | |
1670 | cancel = NULL; | |
1671 | spin_unlock_irq(&ctx->ctx_lock); | |
1672 | ||
1673 | if (NULL != cancel) { | |
1674 | struct io_event tmp; | |
1675 | pr_debug("calling cancel\n"); | |
1676 | memset(&tmp, 0, sizeof(tmp)); | |
1677 | tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user; | |
1678 | tmp.data = kiocb->ki_user_data; | |
1679 | ret = cancel(kiocb, &tmp); | |
1680 | if (!ret) { | |
1681 | /* Cancellation succeeded -- copy the result | |
1682 | * into the user's buffer. | |
1683 | */ | |
1684 | if (copy_to_user(result, &tmp, sizeof(tmp))) | |
1685 | ret = -EFAULT; | |
1686 | } | |
1687 | } else | |
1688 | printk(KERN_DEBUG "iocb has no cancel operation\n"); | |
1689 | ||
1690 | put_ioctx(ctx); | |
1691 | ||
1692 | return ret; | |
1693 | } | |
1694 | ||
1695 | /* io_getevents: | |
1696 | * Attempts to read at least min_nr events and up to nr events from | |
1697 | * the completion queue for the aio_context specified by ctx_id. May | |
1698 | * fail with -EINVAL if ctx_id is invalid, if min_nr is out of range, | |
1699 | * if nr is out of range, if when is out of range. May fail with | |
1700 | * -EFAULT if any of the memory specified to is invalid. May return | |
1701 | * 0 or < min_nr if no events are available and the timeout specified | |
1702 | * by when has elapsed, where when == NULL specifies an infinite | |
1703 | * timeout. Note that the timeout pointed to by when is relative and | |
1704 | * will be updated if not NULL and the operation blocks. Will fail | |
1705 | * with -ENOSYS if not implemented. | |
1706 | */ | |
1707 | asmlinkage long sys_io_getevents(aio_context_t ctx_id, | |
1708 | long min_nr, | |
1709 | long nr, | |
1710 | struct io_event __user *events, | |
1711 | struct timespec __user *timeout) | |
1712 | { | |
1713 | struct kioctx *ioctx = lookup_ioctx(ctx_id); | |
1714 | long ret = -EINVAL; | |
1715 | ||
1716 | if (likely(ioctx)) { | |
1717 | if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0)) | |
1718 | ret = read_events(ioctx, min_nr, nr, events, timeout); | |
1719 | put_ioctx(ioctx); | |
1720 | } | |
1721 | ||
1722 | return ret; | |
1723 | } | |
1724 | ||
1725 | __initcall(aio_setup); | |
1726 | ||
1727 | EXPORT_SYMBOL(aio_complete); | |
1728 | EXPORT_SYMBOL(aio_put_req); | |
1729 | EXPORT_SYMBOL(wait_on_sync_kiocb); |