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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 | #define pr_fmt(fmt) "%s: " fmt, __func__ | |
12 | ||
13 | #include <linux/kernel.h> | |
14 | #include <linux/init.h> | |
15 | #include <linux/errno.h> | |
16 | #include <linux/time.h> | |
17 | #include <linux/aio_abi.h> | |
18 | #include <linux/export.h> | |
19 | #include <linux/syscalls.h> | |
20 | #include <linux/backing-dev.h> | |
21 | #include <linux/uio.h> | |
22 | ||
23 | #include <linux/sched.h> | |
24 | #include <linux/fs.h> | |
25 | #include <linux/file.h> | |
26 | #include <linux/mm.h> | |
27 | #include <linux/mman.h> | |
28 | #include <linux/mmu_context.h> | |
29 | #include <linux/slab.h> | |
30 | #include <linux/timer.h> | |
31 | #include <linux/aio.h> | |
32 | #include <linux/highmem.h> | |
33 | #include <linux/workqueue.h> | |
34 | #include <linux/security.h> | |
35 | #include <linux/eventfd.h> | |
36 | #include <linux/blkdev.h> | |
37 | #include <linux/compat.h> | |
38 | ||
39 | #include <asm/kmap_types.h> | |
40 | #include <asm/uaccess.h> | |
41 | ||
42 | #define AIO_RING_MAGIC 0xa10a10a1 | |
43 | #define AIO_RING_COMPAT_FEATURES 1 | |
44 | #define AIO_RING_INCOMPAT_FEATURES 0 | |
45 | struct aio_ring { | |
46 | unsigned id; /* kernel internal index number */ | |
47 | unsigned nr; /* number of io_events */ | |
48 | unsigned head; | |
49 | unsigned tail; | |
50 | ||
51 | unsigned magic; | |
52 | unsigned compat_features; | |
53 | unsigned incompat_features; | |
54 | unsigned header_length; /* size of aio_ring */ | |
55 | ||
56 | ||
57 | struct io_event io_events[0]; | |
58 | }; /* 128 bytes + ring size */ | |
59 | ||
60 | #define AIO_RING_PAGES 8 | |
61 | ||
62 | struct kioctx { | |
63 | atomic_t users; | |
64 | atomic_t dead; | |
65 | ||
66 | /* This needs improving */ | |
67 | unsigned long user_id; | |
68 | struct hlist_node list; | |
69 | ||
70 | /* | |
71 | * This is what userspace passed to io_setup(), it's not used for | |
72 | * anything but counting against the global max_reqs quota. | |
73 | * | |
74 | * The real limit is nr_events - 1, which will be larger (see | |
75 | * aio_setup_ring()) | |
76 | */ | |
77 | unsigned max_reqs; | |
78 | ||
79 | /* Size of ringbuffer, in units of struct io_event */ | |
80 | unsigned nr_events; | |
81 | ||
82 | unsigned long mmap_base; | |
83 | unsigned long mmap_size; | |
84 | ||
85 | struct page **ring_pages; | |
86 | long nr_pages; | |
87 | ||
88 | struct rcu_head rcu_head; | |
89 | struct work_struct rcu_work; | |
90 | ||
91 | struct { | |
92 | atomic_t reqs_active; | |
93 | } ____cacheline_aligned_in_smp; | |
94 | ||
95 | struct { | |
96 | spinlock_t ctx_lock; | |
97 | struct list_head active_reqs; /* used for cancellation */ | |
98 | } ____cacheline_aligned_in_smp; | |
99 | ||
100 | struct { | |
101 | struct mutex ring_lock; | |
102 | wait_queue_head_t wait; | |
103 | } ____cacheline_aligned_in_smp; | |
104 | ||
105 | struct { | |
106 | unsigned tail; | |
107 | spinlock_t completion_lock; | |
108 | } ____cacheline_aligned_in_smp; | |
109 | ||
110 | struct page *internal_pages[AIO_RING_PAGES]; | |
111 | }; | |
112 | ||
113 | /*------ sysctl variables----*/ | |
114 | static DEFINE_SPINLOCK(aio_nr_lock); | |
115 | unsigned long aio_nr; /* current system wide number of aio requests */ | |
116 | unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */ | |
117 | /*----end sysctl variables---*/ | |
118 | ||
119 | static struct kmem_cache *kiocb_cachep; | |
120 | static struct kmem_cache *kioctx_cachep; | |
121 | ||
122 | /* aio_setup | |
123 | * Creates the slab caches used by the aio routines, panic on | |
124 | * failure as this is done early during the boot sequence. | |
125 | */ | |
126 | static int __init aio_setup(void) | |
127 | { | |
128 | kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC); | |
129 | kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC); | |
130 | ||
131 | pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page)); | |
132 | ||
133 | return 0; | |
134 | } | |
135 | __initcall(aio_setup); | |
136 | ||
137 | static void aio_free_ring(struct kioctx *ctx) | |
138 | { | |
139 | long i; | |
140 | ||
141 | for (i = 0; i < ctx->nr_pages; i++) | |
142 | put_page(ctx->ring_pages[i]); | |
143 | ||
144 | if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) | |
145 | kfree(ctx->ring_pages); | |
146 | } | |
147 | ||
148 | static int aio_setup_ring(struct kioctx *ctx) | |
149 | { | |
150 | struct aio_ring *ring; | |
151 | unsigned nr_events = ctx->max_reqs; | |
152 | struct mm_struct *mm = current->mm; | |
153 | unsigned long size, populate; | |
154 | int nr_pages; | |
155 | ||
156 | /* Compensate for the ring buffer's head/tail overlap entry */ | |
157 | nr_events += 2; /* 1 is required, 2 for good luck */ | |
158 | ||
159 | size = sizeof(struct aio_ring); | |
160 | size += sizeof(struct io_event) * nr_events; | |
161 | nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT; | |
162 | ||
163 | if (nr_pages < 0) | |
164 | return -EINVAL; | |
165 | ||
166 | nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event); | |
167 | ||
168 | ctx->nr_events = 0; | |
169 | ctx->ring_pages = ctx->internal_pages; | |
170 | if (nr_pages > AIO_RING_PAGES) { | |
171 | ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *), | |
172 | GFP_KERNEL); | |
173 | if (!ctx->ring_pages) | |
174 | return -ENOMEM; | |
175 | } | |
176 | ||
177 | ctx->mmap_size = nr_pages * PAGE_SIZE; | |
178 | pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size); | |
179 | down_write(&mm->mmap_sem); | |
180 | ctx->mmap_base = do_mmap_pgoff(NULL, 0, ctx->mmap_size, | |
181 | PROT_READ|PROT_WRITE, | |
182 | MAP_ANONYMOUS|MAP_PRIVATE, 0, &populate); | |
183 | if (IS_ERR((void *)ctx->mmap_base)) { | |
184 | up_write(&mm->mmap_sem); | |
185 | ctx->mmap_size = 0; | |
186 | aio_free_ring(ctx); | |
187 | return -EAGAIN; | |
188 | } | |
189 | ||
190 | pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base); | |
191 | ctx->nr_pages = get_user_pages(current, mm, ctx->mmap_base, nr_pages, | |
192 | 1, 0, ctx->ring_pages, NULL); | |
193 | up_write(&mm->mmap_sem); | |
194 | ||
195 | if (unlikely(ctx->nr_pages != nr_pages)) { | |
196 | aio_free_ring(ctx); | |
197 | return -EAGAIN; | |
198 | } | |
199 | if (populate) | |
200 | mm_populate(ctx->mmap_base, populate); | |
201 | ||
202 | ctx->user_id = ctx->mmap_base; | |
203 | ctx->nr_events = nr_events; /* trusted copy */ | |
204 | ||
205 | ring = kmap_atomic(ctx->ring_pages[0]); | |
206 | ring->nr = nr_events; /* user copy */ | |
207 | ring->id = ctx->user_id; | |
208 | ring->head = ring->tail = 0; | |
209 | ring->magic = AIO_RING_MAGIC; | |
210 | ring->compat_features = AIO_RING_COMPAT_FEATURES; | |
211 | ring->incompat_features = AIO_RING_INCOMPAT_FEATURES; | |
212 | ring->header_length = sizeof(struct aio_ring); | |
213 | kunmap_atomic(ring); | |
214 | flush_dcache_page(ctx->ring_pages[0]); | |
215 | ||
216 | return 0; | |
217 | } | |
218 | ||
219 | #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event)) | |
220 | #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event)) | |
221 | #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE) | |
222 | ||
223 | void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel) | |
224 | { | |
225 | struct kioctx *ctx = req->ki_ctx; | |
226 | unsigned long flags; | |
227 | ||
228 | spin_lock_irqsave(&ctx->ctx_lock, flags); | |
229 | ||
230 | if (!req->ki_list.next) | |
231 | list_add(&req->ki_list, &ctx->active_reqs); | |
232 | ||
233 | req->ki_cancel = cancel; | |
234 | ||
235 | spin_unlock_irqrestore(&ctx->ctx_lock, flags); | |
236 | } | |
237 | EXPORT_SYMBOL(kiocb_set_cancel_fn); | |
238 | ||
239 | static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb, | |
240 | struct io_event *res) | |
241 | { | |
242 | kiocb_cancel_fn *old, *cancel; | |
243 | int ret = -EINVAL; | |
244 | ||
245 | /* | |
246 | * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it | |
247 | * actually has a cancel function, hence the cmpxchg() | |
248 | */ | |
249 | ||
250 | cancel = ACCESS_ONCE(kiocb->ki_cancel); | |
251 | do { | |
252 | if (!cancel || cancel == KIOCB_CANCELLED) | |
253 | return ret; | |
254 | ||
255 | old = cancel; | |
256 | cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED); | |
257 | } while (cancel != old); | |
258 | ||
259 | atomic_inc(&kiocb->ki_users); | |
260 | spin_unlock_irq(&ctx->ctx_lock); | |
261 | ||
262 | memset(res, 0, sizeof(*res)); | |
263 | res->obj = (u64)(unsigned long)kiocb->ki_obj.user; | |
264 | res->data = kiocb->ki_user_data; | |
265 | ret = cancel(kiocb, res); | |
266 | ||
267 | spin_lock_irq(&ctx->ctx_lock); | |
268 | ||
269 | return ret; | |
270 | } | |
271 | ||
272 | static void free_ioctx_rcu(struct rcu_head *head) | |
273 | { | |
274 | struct kioctx *ctx = container_of(head, struct kioctx, rcu_head); | |
275 | kmem_cache_free(kioctx_cachep, ctx); | |
276 | } | |
277 | ||
278 | /* | |
279 | * When this function runs, the kioctx has been removed from the "hash table" | |
280 | * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted - | |
281 | * now it's safe to cancel any that need to be. | |
282 | */ | |
283 | static void free_ioctx(struct kioctx *ctx) | |
284 | { | |
285 | struct aio_ring *ring; | |
286 | struct io_event res; | |
287 | struct kiocb *req; | |
288 | unsigned head, avail; | |
289 | ||
290 | spin_lock_irq(&ctx->ctx_lock); | |
291 | ||
292 | while (!list_empty(&ctx->active_reqs)) { | |
293 | req = list_first_entry(&ctx->active_reqs, | |
294 | struct kiocb, ki_list); | |
295 | ||
296 | list_del_init(&req->ki_list); | |
297 | kiocb_cancel(ctx, req, &res); | |
298 | } | |
299 | ||
300 | spin_unlock_irq(&ctx->ctx_lock); | |
301 | ||
302 | ring = kmap_atomic(ctx->ring_pages[0]); | |
303 | head = ring->head; | |
304 | kunmap_atomic(ring); | |
305 | ||
306 | while (atomic_read(&ctx->reqs_active) > 0) { | |
307 | wait_event(ctx->wait, | |
308 | head != ctx->tail || | |
309 | atomic_read(&ctx->reqs_active) <= 0); | |
310 | ||
311 | avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head; | |
312 | ||
313 | atomic_sub(avail, &ctx->reqs_active); | |
314 | head += avail; | |
315 | head %= ctx->nr_events; | |
316 | } | |
317 | ||
318 | WARN_ON(atomic_read(&ctx->reqs_active) < 0); | |
319 | ||
320 | aio_free_ring(ctx); | |
321 | ||
322 | pr_debug("freeing %p\n", ctx); | |
323 | ||
324 | /* | |
325 | * Here the call_rcu() is between the wait_event() for reqs_active to | |
326 | * hit 0, and freeing the ioctx. | |
327 | * | |
328 | * aio_complete() decrements reqs_active, but it has to touch the ioctx | |
329 | * after to issue a wakeup so we use rcu. | |
330 | */ | |
331 | call_rcu(&ctx->rcu_head, free_ioctx_rcu); | |
332 | } | |
333 | ||
334 | static void put_ioctx(struct kioctx *ctx) | |
335 | { | |
336 | if (unlikely(atomic_dec_and_test(&ctx->users))) | |
337 | free_ioctx(ctx); | |
338 | } | |
339 | ||
340 | /* ioctx_alloc | |
341 | * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed. | |
342 | */ | |
343 | static struct kioctx *ioctx_alloc(unsigned nr_events) | |
344 | { | |
345 | struct mm_struct *mm = current->mm; | |
346 | struct kioctx *ctx; | |
347 | int err = -ENOMEM; | |
348 | ||
349 | /* Prevent overflows */ | |
350 | if ((nr_events > (0x10000000U / sizeof(struct io_event))) || | |
351 | (nr_events > (0x10000000U / sizeof(struct kiocb)))) { | |
352 | pr_debug("ENOMEM: nr_events too high\n"); | |
353 | return ERR_PTR(-EINVAL); | |
354 | } | |
355 | ||
356 | if (!nr_events || (unsigned long)nr_events > aio_max_nr) | |
357 | return ERR_PTR(-EAGAIN); | |
358 | ||
359 | ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL); | |
360 | if (!ctx) | |
361 | return ERR_PTR(-ENOMEM); | |
362 | ||
363 | ctx->max_reqs = nr_events; | |
364 | ||
365 | atomic_set(&ctx->users, 2); | |
366 | atomic_set(&ctx->dead, 0); | |
367 | spin_lock_init(&ctx->ctx_lock); | |
368 | spin_lock_init(&ctx->completion_lock); | |
369 | mutex_init(&ctx->ring_lock); | |
370 | init_waitqueue_head(&ctx->wait); | |
371 | ||
372 | INIT_LIST_HEAD(&ctx->active_reqs); | |
373 | ||
374 | if (aio_setup_ring(ctx) < 0) | |
375 | goto out_freectx; | |
376 | ||
377 | /* limit the number of system wide aios */ | |
378 | spin_lock(&aio_nr_lock); | |
379 | if (aio_nr + nr_events > aio_max_nr || | |
380 | aio_nr + nr_events < aio_nr) { | |
381 | spin_unlock(&aio_nr_lock); | |
382 | goto out_cleanup; | |
383 | } | |
384 | aio_nr += ctx->max_reqs; | |
385 | spin_unlock(&aio_nr_lock); | |
386 | ||
387 | /* now link into global list. */ | |
388 | spin_lock(&mm->ioctx_lock); | |
389 | hlist_add_head_rcu(&ctx->list, &mm->ioctx_list); | |
390 | spin_unlock(&mm->ioctx_lock); | |
391 | ||
392 | pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n", | |
393 | ctx, ctx->user_id, mm, ctx->nr_events); | |
394 | return ctx; | |
395 | ||
396 | out_cleanup: | |
397 | err = -EAGAIN; | |
398 | aio_free_ring(ctx); | |
399 | out_freectx: | |
400 | kmem_cache_free(kioctx_cachep, ctx); | |
401 | pr_debug("error allocating ioctx %d\n", err); | |
402 | return ERR_PTR(err); | |
403 | } | |
404 | ||
405 | static void kill_ioctx_work(struct work_struct *work) | |
406 | { | |
407 | struct kioctx *ctx = container_of(work, struct kioctx, rcu_work); | |
408 | ||
409 | wake_up_all(&ctx->wait); | |
410 | put_ioctx(ctx); | |
411 | } | |
412 | ||
413 | static void kill_ioctx_rcu(struct rcu_head *head) | |
414 | { | |
415 | struct kioctx *ctx = container_of(head, struct kioctx, rcu_head); | |
416 | ||
417 | INIT_WORK(&ctx->rcu_work, kill_ioctx_work); | |
418 | schedule_work(&ctx->rcu_work); | |
419 | } | |
420 | ||
421 | /* kill_ioctx | |
422 | * Cancels all outstanding aio requests on an aio context. Used | |
423 | * when the processes owning a context have all exited to encourage | |
424 | * the rapid destruction of the kioctx. | |
425 | */ | |
426 | static void kill_ioctx(struct kioctx *ctx) | |
427 | { | |
428 | if (!atomic_xchg(&ctx->dead, 1)) { | |
429 | hlist_del_rcu(&ctx->list); | |
430 | ||
431 | /* | |
432 | * It'd be more correct to do this in free_ioctx(), after all | |
433 | * the outstanding kiocbs have finished - but by then io_destroy | |
434 | * has already returned, so io_setup() could potentially return | |
435 | * -EAGAIN with no ioctxs actually in use (as far as userspace | |
436 | * could tell). | |
437 | */ | |
438 | spin_lock(&aio_nr_lock); | |
439 | BUG_ON(aio_nr - ctx->max_reqs > aio_nr); | |
440 | aio_nr -= ctx->max_reqs; | |
441 | spin_unlock(&aio_nr_lock); | |
442 | ||
443 | if (ctx->mmap_size) | |
444 | vm_munmap(ctx->mmap_base, ctx->mmap_size); | |
445 | ||
446 | /* Between hlist_del_rcu() and dropping the initial ref */ | |
447 | call_rcu(&ctx->rcu_head, kill_ioctx_rcu); | |
448 | } | |
449 | } | |
450 | ||
451 | /* wait_on_sync_kiocb: | |
452 | * Waits on the given sync kiocb to complete. | |
453 | */ | |
454 | ssize_t wait_on_sync_kiocb(struct kiocb *iocb) | |
455 | { | |
456 | while (atomic_read(&iocb->ki_users)) { | |
457 | set_current_state(TASK_UNINTERRUPTIBLE); | |
458 | if (!atomic_read(&iocb->ki_users)) | |
459 | break; | |
460 | io_schedule(); | |
461 | } | |
462 | __set_current_state(TASK_RUNNING); | |
463 | return iocb->ki_user_data; | |
464 | } | |
465 | EXPORT_SYMBOL(wait_on_sync_kiocb); | |
466 | ||
467 | /* | |
468 | * exit_aio: called when the last user of mm goes away. At this point, there is | |
469 | * no way for any new requests to be submited or any of the io_* syscalls to be | |
470 | * called on the context. | |
471 | * | |
472 | * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on | |
473 | * them. | |
474 | */ | |
475 | void exit_aio(struct mm_struct *mm) | |
476 | { | |
477 | struct kioctx *ctx; | |
478 | struct hlist_node *n; | |
479 | ||
480 | hlist_for_each_entry_safe(ctx, n, &mm->ioctx_list, list) { | |
481 | if (1 != atomic_read(&ctx->users)) | |
482 | printk(KERN_DEBUG | |
483 | "exit_aio:ioctx still alive: %d %d %d\n", | |
484 | atomic_read(&ctx->users), | |
485 | atomic_read(&ctx->dead), | |
486 | atomic_read(&ctx->reqs_active)); | |
487 | /* | |
488 | * We don't need to bother with munmap() here - | |
489 | * exit_mmap(mm) is coming and it'll unmap everything. | |
490 | * Since aio_free_ring() uses non-zero ->mmap_size | |
491 | * as indicator that it needs to unmap the area, | |
492 | * just set it to 0; aio_free_ring() is the only | |
493 | * place that uses ->mmap_size, so it's safe. | |
494 | */ | |
495 | ctx->mmap_size = 0; | |
496 | ||
497 | kill_ioctx(ctx); | |
498 | } | |
499 | } | |
500 | ||
501 | /* aio_get_req | |
502 | * Allocate a slot for an aio request. Increments the ki_users count | |
503 | * of the kioctx so that the kioctx stays around until all requests are | |
504 | * complete. Returns NULL if no requests are free. | |
505 | * | |
506 | * Returns with kiocb->ki_users set to 2. The io submit code path holds | |
507 | * an extra reference while submitting the i/o. | |
508 | * This prevents races between the aio code path referencing the | |
509 | * req (after submitting it) and aio_complete() freeing the req. | |
510 | */ | |
511 | static inline struct kiocb *aio_get_req(struct kioctx *ctx) | |
512 | { | |
513 | struct kiocb *req; | |
514 | ||
515 | if (atomic_read(&ctx->reqs_active) >= ctx->nr_events) | |
516 | return NULL; | |
517 | ||
518 | if (atomic_inc_return(&ctx->reqs_active) > ctx->nr_events - 1) | |
519 | goto out_put; | |
520 | ||
521 | req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO); | |
522 | if (unlikely(!req)) | |
523 | goto out_put; | |
524 | ||
525 | atomic_set(&req->ki_users, 2); | |
526 | req->ki_ctx = ctx; | |
527 | ||
528 | return req; | |
529 | out_put: | |
530 | atomic_dec(&ctx->reqs_active); | |
531 | return NULL; | |
532 | } | |
533 | ||
534 | static void kiocb_free(struct kiocb *req) | |
535 | { | |
536 | if (req->ki_filp) | |
537 | fput(req->ki_filp); | |
538 | if (req->ki_eventfd != NULL) | |
539 | eventfd_ctx_put(req->ki_eventfd); | |
540 | if (req->ki_dtor) | |
541 | req->ki_dtor(req); | |
542 | if (req->ki_iovec != &req->ki_inline_vec) | |
543 | kfree(req->ki_iovec); | |
544 | kmem_cache_free(kiocb_cachep, req); | |
545 | } | |
546 | ||
547 | void aio_put_req(struct kiocb *req) | |
548 | { | |
549 | if (atomic_dec_and_test(&req->ki_users)) | |
550 | kiocb_free(req); | |
551 | } | |
552 | EXPORT_SYMBOL(aio_put_req); | |
553 | ||
554 | static struct kioctx *lookup_ioctx(unsigned long ctx_id) | |
555 | { | |
556 | struct mm_struct *mm = current->mm; | |
557 | struct kioctx *ctx, *ret = NULL; | |
558 | ||
559 | rcu_read_lock(); | |
560 | ||
561 | hlist_for_each_entry_rcu(ctx, &mm->ioctx_list, list) { | |
562 | if (ctx->user_id == ctx_id) { | |
563 | atomic_inc(&ctx->users); | |
564 | ret = ctx; | |
565 | break; | |
566 | } | |
567 | } | |
568 | ||
569 | rcu_read_unlock(); | |
570 | return ret; | |
571 | } | |
572 | ||
573 | /* aio_complete | |
574 | * Called when the io request on the given iocb is complete. | |
575 | */ | |
576 | void aio_complete(struct kiocb *iocb, long res, long res2) | |
577 | { | |
578 | struct kioctx *ctx = iocb->ki_ctx; | |
579 | struct aio_ring *ring; | |
580 | struct io_event *ev_page, *event; | |
581 | unsigned long flags; | |
582 | unsigned tail, pos; | |
583 | ||
584 | /* | |
585 | * Special case handling for sync iocbs: | |
586 | * - events go directly into the iocb for fast handling | |
587 | * - the sync task with the iocb in its stack holds the single iocb | |
588 | * ref, no other paths have a way to get another ref | |
589 | * - the sync task helpfully left a reference to itself in the iocb | |
590 | */ | |
591 | if (is_sync_kiocb(iocb)) { | |
592 | BUG_ON(atomic_read(&iocb->ki_users) != 1); | |
593 | iocb->ki_user_data = res; | |
594 | atomic_set(&iocb->ki_users, 0); | |
595 | wake_up_process(iocb->ki_obj.tsk); | |
596 | return; | |
597 | } | |
598 | ||
599 | /* | |
600 | * Take rcu_read_lock() in case the kioctx is being destroyed, as we | |
601 | * need to issue a wakeup after decrementing reqs_active. | |
602 | */ | |
603 | rcu_read_lock(); | |
604 | ||
605 | if (iocb->ki_list.next) { | |
606 | unsigned long flags; | |
607 | ||
608 | spin_lock_irqsave(&ctx->ctx_lock, flags); | |
609 | list_del(&iocb->ki_list); | |
610 | spin_unlock_irqrestore(&ctx->ctx_lock, flags); | |
611 | } | |
612 | ||
613 | /* | |
614 | * cancelled requests don't get events, userland was given one | |
615 | * when the event got cancelled. | |
616 | */ | |
617 | if (unlikely(xchg(&iocb->ki_cancel, | |
618 | KIOCB_CANCELLED) == KIOCB_CANCELLED)) { | |
619 | atomic_dec(&ctx->reqs_active); | |
620 | /* Still need the wake_up in case free_ioctx is waiting */ | |
621 | goto put_rq; | |
622 | } | |
623 | ||
624 | /* | |
625 | * Add a completion event to the ring buffer. Must be done holding | |
626 | * ctx->ctx_lock to prevent other code from messing with the tail | |
627 | * pointer since we might be called from irq context. | |
628 | */ | |
629 | spin_lock_irqsave(&ctx->completion_lock, flags); | |
630 | ||
631 | tail = ctx->tail; | |
632 | pos = tail + AIO_EVENTS_OFFSET; | |
633 | ||
634 | if (++tail >= ctx->nr_events) | |
635 | tail = 0; | |
636 | ||
637 | ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]); | |
638 | event = ev_page + pos % AIO_EVENTS_PER_PAGE; | |
639 | ||
640 | event->obj = (u64)(unsigned long)iocb->ki_obj.user; | |
641 | event->data = iocb->ki_user_data; | |
642 | event->res = res; | |
643 | event->res2 = res2; | |
644 | ||
645 | kunmap_atomic(ev_page); | |
646 | flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]); | |
647 | ||
648 | pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n", | |
649 | ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data, | |
650 | res, res2); | |
651 | ||
652 | /* after flagging the request as done, we | |
653 | * must never even look at it again | |
654 | */ | |
655 | smp_wmb(); /* make event visible before updating tail */ | |
656 | ||
657 | ctx->tail = tail; | |
658 | ||
659 | ring = kmap_atomic(ctx->ring_pages[0]); | |
660 | ring->tail = tail; | |
661 | kunmap_atomic(ring); | |
662 | flush_dcache_page(ctx->ring_pages[0]); | |
663 | ||
664 | spin_unlock_irqrestore(&ctx->completion_lock, flags); | |
665 | ||
666 | pr_debug("added to ring %p at [%u]\n", iocb, tail); | |
667 | ||
668 | /* | |
669 | * Check if the user asked us to deliver the result through an | |
670 | * eventfd. The eventfd_signal() function is safe to be called | |
671 | * from IRQ context. | |
672 | */ | |
673 | if (iocb->ki_eventfd != NULL) | |
674 | eventfd_signal(iocb->ki_eventfd, 1); | |
675 | ||
676 | put_rq: | |
677 | /* everything turned out well, dispose of the aiocb. */ | |
678 | aio_put_req(iocb); | |
679 | ||
680 | /* | |
681 | * We have to order our ring_info tail store above and test | |
682 | * of the wait list below outside the wait lock. This is | |
683 | * like in wake_up_bit() where clearing a bit has to be | |
684 | * ordered with the unlocked test. | |
685 | */ | |
686 | smp_mb(); | |
687 | ||
688 | if (waitqueue_active(&ctx->wait)) | |
689 | wake_up(&ctx->wait); | |
690 | ||
691 | rcu_read_unlock(); | |
692 | } | |
693 | EXPORT_SYMBOL(aio_complete); | |
694 | ||
695 | /* aio_read_events | |
696 | * Pull an event off of the ioctx's event ring. Returns the number of | |
697 | * events fetched | |
698 | */ | |
699 | static long aio_read_events_ring(struct kioctx *ctx, | |
700 | struct io_event __user *event, long nr) | |
701 | { | |
702 | struct aio_ring *ring; | |
703 | unsigned head, pos; | |
704 | long ret = 0; | |
705 | int copy_ret; | |
706 | ||
707 | mutex_lock(&ctx->ring_lock); | |
708 | ||
709 | ring = kmap_atomic(ctx->ring_pages[0]); | |
710 | head = ring->head; | |
711 | kunmap_atomic(ring); | |
712 | ||
713 | pr_debug("h%u t%u m%u\n", head, ctx->tail, ctx->nr_events); | |
714 | ||
715 | if (head == ctx->tail) | |
716 | goto out; | |
717 | ||
718 | while (ret < nr) { | |
719 | long avail; | |
720 | struct io_event *ev; | |
721 | struct page *page; | |
722 | ||
723 | avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head; | |
724 | if (head == ctx->tail) | |
725 | break; | |
726 | ||
727 | avail = min(avail, nr - ret); | |
728 | avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - | |
729 | ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE)); | |
730 | ||
731 | pos = head + AIO_EVENTS_OFFSET; | |
732 | page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]; | |
733 | pos %= AIO_EVENTS_PER_PAGE; | |
734 | ||
735 | ev = kmap(page); | |
736 | copy_ret = copy_to_user(event + ret, ev + pos, | |
737 | sizeof(*ev) * avail); | |
738 | kunmap(page); | |
739 | ||
740 | if (unlikely(copy_ret)) { | |
741 | ret = -EFAULT; | |
742 | goto out; | |
743 | } | |
744 | ||
745 | ret += avail; | |
746 | head += avail; | |
747 | head %= ctx->nr_events; | |
748 | } | |
749 | ||
750 | ring = kmap_atomic(ctx->ring_pages[0]); | |
751 | ring->head = head; | |
752 | kunmap_atomic(ring); | |
753 | flush_dcache_page(ctx->ring_pages[0]); | |
754 | ||
755 | pr_debug("%li h%u t%u\n", ret, head, ctx->tail); | |
756 | ||
757 | atomic_sub(ret, &ctx->reqs_active); | |
758 | out: | |
759 | mutex_unlock(&ctx->ring_lock); | |
760 | ||
761 | return ret; | |
762 | } | |
763 | ||
764 | static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr, | |
765 | struct io_event __user *event, long *i) | |
766 | { | |
767 | long ret = aio_read_events_ring(ctx, event + *i, nr - *i); | |
768 | ||
769 | if (ret > 0) | |
770 | *i += ret; | |
771 | ||
772 | if (unlikely(atomic_read(&ctx->dead))) | |
773 | ret = -EINVAL; | |
774 | ||
775 | if (!*i) | |
776 | *i = ret; | |
777 | ||
778 | return ret < 0 || *i >= min_nr; | |
779 | } | |
780 | ||
781 | static long read_events(struct kioctx *ctx, long min_nr, long nr, | |
782 | struct io_event __user *event, | |
783 | struct timespec __user *timeout) | |
784 | { | |
785 | ktime_t until = { .tv64 = KTIME_MAX }; | |
786 | long ret = 0; | |
787 | ||
788 | if (timeout) { | |
789 | struct timespec ts; | |
790 | ||
791 | if (unlikely(copy_from_user(&ts, timeout, sizeof(ts)))) | |
792 | return -EFAULT; | |
793 | ||
794 | until = timespec_to_ktime(ts); | |
795 | } | |
796 | ||
797 | /* | |
798 | * Note that aio_read_events() is being called as the conditional - i.e. | |
799 | * we're calling it after prepare_to_wait() has set task state to | |
800 | * TASK_INTERRUPTIBLE. | |
801 | * | |
802 | * But aio_read_events() can block, and if it blocks it's going to flip | |
803 | * the task state back to TASK_RUNNING. | |
804 | * | |
805 | * This should be ok, provided it doesn't flip the state back to | |
806 | * TASK_RUNNING and return 0 too much - that causes us to spin. That | |
807 | * will only happen if the mutex_lock() call blocks, and we then find | |
808 | * the ringbuffer empty. So in practice we should be ok, but it's | |
809 | * something to be aware of when touching this code. | |
810 | */ | |
811 | wait_event_interruptible_hrtimeout(ctx->wait, | |
812 | aio_read_events(ctx, min_nr, nr, event, &ret), until); | |
813 | ||
814 | if (!ret && signal_pending(current)) | |
815 | ret = -EINTR; | |
816 | ||
817 | return ret; | |
818 | } | |
819 | ||
820 | /* sys_io_setup: | |
821 | * Create an aio_context capable of receiving at least nr_events. | |
822 | * ctxp must not point to an aio_context that already exists, and | |
823 | * must be initialized to 0 prior to the call. On successful | |
824 | * creation of the aio_context, *ctxp is filled in with the resulting | |
825 | * handle. May fail with -EINVAL if *ctxp is not initialized, | |
826 | * if the specified nr_events exceeds internal limits. May fail | |
827 | * with -EAGAIN if the specified nr_events exceeds the user's limit | |
828 | * of available events. May fail with -ENOMEM if insufficient kernel | |
829 | * resources are available. May fail with -EFAULT if an invalid | |
830 | * pointer is passed for ctxp. Will fail with -ENOSYS if not | |
831 | * implemented. | |
832 | */ | |
833 | SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp) | |
834 | { | |
835 | struct kioctx *ioctx = NULL; | |
836 | unsigned long ctx; | |
837 | long ret; | |
838 | ||
839 | ret = get_user(ctx, ctxp); | |
840 | if (unlikely(ret)) | |
841 | goto out; | |
842 | ||
843 | ret = -EINVAL; | |
844 | if (unlikely(ctx || nr_events == 0)) { | |
845 | pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n", | |
846 | ctx, nr_events); | |
847 | goto out; | |
848 | } | |
849 | ||
850 | ioctx = ioctx_alloc(nr_events); | |
851 | ret = PTR_ERR(ioctx); | |
852 | if (!IS_ERR(ioctx)) { | |
853 | ret = put_user(ioctx->user_id, ctxp); | |
854 | if (ret) | |
855 | kill_ioctx(ioctx); | |
856 | put_ioctx(ioctx); | |
857 | } | |
858 | ||
859 | out: | |
860 | return ret; | |
861 | } | |
862 | ||
863 | /* sys_io_destroy: | |
864 | * Destroy the aio_context specified. May cancel any outstanding | |
865 | * AIOs and block on completion. Will fail with -ENOSYS if not | |
866 | * implemented. May fail with -EINVAL if the context pointed to | |
867 | * is invalid. | |
868 | */ | |
869 | SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx) | |
870 | { | |
871 | struct kioctx *ioctx = lookup_ioctx(ctx); | |
872 | if (likely(NULL != ioctx)) { | |
873 | kill_ioctx(ioctx); | |
874 | put_ioctx(ioctx); | |
875 | return 0; | |
876 | } | |
877 | pr_debug("EINVAL: io_destroy: invalid context id\n"); | |
878 | return -EINVAL; | |
879 | } | |
880 | ||
881 | static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret) | |
882 | { | |
883 | struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg]; | |
884 | ||
885 | BUG_ON(ret <= 0); | |
886 | ||
887 | while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) { | |
888 | ssize_t this = min((ssize_t)iov->iov_len, ret); | |
889 | iov->iov_base += this; | |
890 | iov->iov_len -= this; | |
891 | iocb->ki_left -= this; | |
892 | ret -= this; | |
893 | if (iov->iov_len == 0) { | |
894 | iocb->ki_cur_seg++; | |
895 | iov++; | |
896 | } | |
897 | } | |
898 | ||
899 | /* the caller should not have done more io than what fit in | |
900 | * the remaining iovecs */ | |
901 | BUG_ON(ret > 0 && iocb->ki_left == 0); | |
902 | } | |
903 | ||
904 | typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *, | |
905 | unsigned long, loff_t); | |
906 | ||
907 | static ssize_t aio_rw_vect_retry(struct kiocb *iocb, int rw, aio_rw_op *rw_op) | |
908 | { | |
909 | struct file *file = iocb->ki_filp; | |
910 | struct address_space *mapping = file->f_mapping; | |
911 | struct inode *inode = mapping->host; | |
912 | ssize_t ret = 0; | |
913 | ||
914 | /* This matches the pread()/pwrite() logic */ | |
915 | if (iocb->ki_pos < 0) | |
916 | return -EINVAL; | |
917 | ||
918 | if (rw == WRITE) | |
919 | file_start_write(file); | |
920 | do { | |
921 | ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg], | |
922 | iocb->ki_nr_segs - iocb->ki_cur_seg, | |
923 | iocb->ki_pos); | |
924 | if (ret > 0) | |
925 | aio_advance_iovec(iocb, ret); | |
926 | ||
927 | /* retry all partial writes. retry partial reads as long as its a | |
928 | * regular file. */ | |
929 | } while (ret > 0 && iocb->ki_left > 0 && | |
930 | (rw == WRITE || | |
931 | (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode)))); | |
932 | if (rw == WRITE) | |
933 | file_end_write(file); | |
934 | ||
935 | /* This means we must have transferred all that we could */ | |
936 | /* No need to retry anymore */ | |
937 | if ((ret == 0) || (iocb->ki_left == 0)) | |
938 | ret = iocb->ki_nbytes - iocb->ki_left; | |
939 | ||
940 | /* If we managed to write some out we return that, rather than | |
941 | * the eventual error. */ | |
942 | if (rw == WRITE | |
943 | && ret < 0 && ret != -EIOCBQUEUED | |
944 | && iocb->ki_nbytes - iocb->ki_left) | |
945 | ret = iocb->ki_nbytes - iocb->ki_left; | |
946 | ||
947 | return ret; | |
948 | } | |
949 | ||
950 | static ssize_t aio_setup_vectored_rw(int rw, struct kiocb *kiocb, bool compat) | |
951 | { | |
952 | ssize_t ret; | |
953 | ||
954 | kiocb->ki_nr_segs = kiocb->ki_nbytes; | |
955 | ||
956 | #ifdef CONFIG_COMPAT | |
957 | if (compat) | |
958 | ret = compat_rw_copy_check_uvector(rw, | |
959 | (struct compat_iovec __user *)kiocb->ki_buf, | |
960 | kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec, | |
961 | &kiocb->ki_iovec); | |
962 | else | |
963 | #endif | |
964 | ret = rw_copy_check_uvector(rw, | |
965 | (struct iovec __user *)kiocb->ki_buf, | |
966 | kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec, | |
967 | &kiocb->ki_iovec); | |
968 | if (ret < 0) | |
969 | return ret; | |
970 | ||
971 | /* ki_nbytes now reflect bytes instead of segs */ | |
972 | kiocb->ki_nbytes = ret; | |
973 | return 0; | |
974 | } | |
975 | ||
976 | static ssize_t aio_setup_single_vector(int rw, struct kiocb *kiocb) | |
977 | { | |
978 | if (unlikely(!access_ok(!rw, kiocb->ki_buf, kiocb->ki_nbytes))) | |
979 | return -EFAULT; | |
980 | ||
981 | kiocb->ki_iovec = &kiocb->ki_inline_vec; | |
982 | kiocb->ki_iovec->iov_base = kiocb->ki_buf; | |
983 | kiocb->ki_iovec->iov_len = kiocb->ki_nbytes; | |
984 | kiocb->ki_nr_segs = 1; | |
985 | return 0; | |
986 | } | |
987 | ||
988 | /* | |
989 | * aio_setup_iocb: | |
990 | * Performs the initial checks and aio retry method | |
991 | * setup for the kiocb at the time of io submission. | |
992 | */ | |
993 | static ssize_t aio_run_iocb(struct kiocb *req, bool compat) | |
994 | { | |
995 | struct file *file = req->ki_filp; | |
996 | ssize_t ret; | |
997 | int rw; | |
998 | fmode_t mode; | |
999 | aio_rw_op *rw_op; | |
1000 | ||
1001 | switch (req->ki_opcode) { | |
1002 | case IOCB_CMD_PREAD: | |
1003 | case IOCB_CMD_PREADV: | |
1004 | mode = FMODE_READ; | |
1005 | rw = READ; | |
1006 | rw_op = file->f_op->aio_read; | |
1007 | goto rw_common; | |
1008 | ||
1009 | case IOCB_CMD_PWRITE: | |
1010 | case IOCB_CMD_PWRITEV: | |
1011 | mode = FMODE_WRITE; | |
1012 | rw = WRITE; | |
1013 | rw_op = file->f_op->aio_write; | |
1014 | goto rw_common; | |
1015 | rw_common: | |
1016 | if (unlikely(!(file->f_mode & mode))) | |
1017 | return -EBADF; | |
1018 | ||
1019 | if (!rw_op) | |
1020 | return -EINVAL; | |
1021 | ||
1022 | ret = (req->ki_opcode == IOCB_CMD_PREADV || | |
1023 | req->ki_opcode == IOCB_CMD_PWRITEV) | |
1024 | ? aio_setup_vectored_rw(rw, req, compat) | |
1025 | : aio_setup_single_vector(rw, req); | |
1026 | if (ret) | |
1027 | return ret; | |
1028 | ||
1029 | ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes); | |
1030 | if (ret < 0) | |
1031 | return ret; | |
1032 | ||
1033 | req->ki_nbytes = ret; | |
1034 | req->ki_left = ret; | |
1035 | ||
1036 | ret = aio_rw_vect_retry(req, rw, rw_op); | |
1037 | break; | |
1038 | ||
1039 | case IOCB_CMD_FDSYNC: | |
1040 | if (!file->f_op->aio_fsync) | |
1041 | return -EINVAL; | |
1042 | ||
1043 | ret = file->f_op->aio_fsync(req, 1); | |
1044 | break; | |
1045 | ||
1046 | case IOCB_CMD_FSYNC: | |
1047 | if (!file->f_op->aio_fsync) | |
1048 | return -EINVAL; | |
1049 | ||
1050 | ret = file->f_op->aio_fsync(req, 0); | |
1051 | break; | |
1052 | ||
1053 | default: | |
1054 | pr_debug("EINVAL: no operation provided\n"); | |
1055 | return -EINVAL; | |
1056 | } | |
1057 | ||
1058 | if (ret != -EIOCBQUEUED) { | |
1059 | /* | |
1060 | * There's no easy way to restart the syscall since other AIO's | |
1061 | * may be already running. Just fail this IO with EINTR. | |
1062 | */ | |
1063 | if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR || | |
1064 | ret == -ERESTARTNOHAND || | |
1065 | ret == -ERESTART_RESTARTBLOCK)) | |
1066 | ret = -EINTR; | |
1067 | aio_complete(req, ret, 0); | |
1068 | } | |
1069 | ||
1070 | return 0; | |
1071 | } | |
1072 | ||
1073 | static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, | |
1074 | struct iocb *iocb, bool compat) | |
1075 | { | |
1076 | struct kiocb *req; | |
1077 | ssize_t ret; | |
1078 | ||
1079 | /* enforce forwards compatibility on users */ | |
1080 | if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) { | |
1081 | pr_debug("EINVAL: reserve field set\n"); | |
1082 | return -EINVAL; | |
1083 | } | |
1084 | ||
1085 | /* prevent overflows */ | |
1086 | if (unlikely( | |
1087 | (iocb->aio_buf != (unsigned long)iocb->aio_buf) || | |
1088 | (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) || | |
1089 | ((ssize_t)iocb->aio_nbytes < 0) | |
1090 | )) { | |
1091 | pr_debug("EINVAL: io_submit: overflow check\n"); | |
1092 | return -EINVAL; | |
1093 | } | |
1094 | ||
1095 | req = aio_get_req(ctx); | |
1096 | if (unlikely(!req)) | |
1097 | return -EAGAIN; | |
1098 | ||
1099 | req->ki_filp = fget(iocb->aio_fildes); | |
1100 | if (unlikely(!req->ki_filp)) { | |
1101 | ret = -EBADF; | |
1102 | goto out_put_req; | |
1103 | } | |
1104 | ||
1105 | if (iocb->aio_flags & IOCB_FLAG_RESFD) { | |
1106 | /* | |
1107 | * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an | |
1108 | * instance of the file* now. The file descriptor must be | |
1109 | * an eventfd() fd, and will be signaled for each completed | |
1110 | * event using the eventfd_signal() function. | |
1111 | */ | |
1112 | req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd); | |
1113 | if (IS_ERR(req->ki_eventfd)) { | |
1114 | ret = PTR_ERR(req->ki_eventfd); | |
1115 | req->ki_eventfd = NULL; | |
1116 | goto out_put_req; | |
1117 | } | |
1118 | } | |
1119 | ||
1120 | ret = put_user(KIOCB_KEY, &user_iocb->aio_key); | |
1121 | if (unlikely(ret)) { | |
1122 | pr_debug("EFAULT: aio_key\n"); | |
1123 | goto out_put_req; | |
1124 | } | |
1125 | ||
1126 | req->ki_obj.user = user_iocb; | |
1127 | req->ki_user_data = iocb->aio_data; | |
1128 | req->ki_pos = iocb->aio_offset; | |
1129 | ||
1130 | req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf; | |
1131 | req->ki_left = req->ki_nbytes = iocb->aio_nbytes; | |
1132 | req->ki_opcode = iocb->aio_lio_opcode; | |
1133 | ||
1134 | ret = aio_run_iocb(req, compat); | |
1135 | if (ret) | |
1136 | goto out_put_req; | |
1137 | ||
1138 | aio_put_req(req); /* drop extra ref to req */ | |
1139 | return 0; | |
1140 | out_put_req: | |
1141 | atomic_dec(&ctx->reqs_active); | |
1142 | aio_put_req(req); /* drop extra ref to req */ | |
1143 | aio_put_req(req); /* drop i/o ref to req */ | |
1144 | return ret; | |
1145 | } | |
1146 | ||
1147 | long do_io_submit(aio_context_t ctx_id, long nr, | |
1148 | struct iocb __user *__user *iocbpp, bool compat) | |
1149 | { | |
1150 | struct kioctx *ctx; | |
1151 | long ret = 0; | |
1152 | int i = 0; | |
1153 | struct blk_plug plug; | |
1154 | ||
1155 | if (unlikely(nr < 0)) | |
1156 | return -EINVAL; | |
1157 | ||
1158 | if (unlikely(nr > LONG_MAX/sizeof(*iocbpp))) | |
1159 | nr = LONG_MAX/sizeof(*iocbpp); | |
1160 | ||
1161 | if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp))))) | |
1162 | return -EFAULT; | |
1163 | ||
1164 | ctx = lookup_ioctx(ctx_id); | |
1165 | if (unlikely(!ctx)) { | |
1166 | pr_debug("EINVAL: invalid context id\n"); | |
1167 | return -EINVAL; | |
1168 | } | |
1169 | ||
1170 | blk_start_plug(&plug); | |
1171 | ||
1172 | /* | |
1173 | * AKPM: should this return a partial result if some of the IOs were | |
1174 | * successfully submitted? | |
1175 | */ | |
1176 | for (i=0; i<nr; i++) { | |
1177 | struct iocb __user *user_iocb; | |
1178 | struct iocb tmp; | |
1179 | ||
1180 | if (unlikely(__get_user(user_iocb, iocbpp + i))) { | |
1181 | ret = -EFAULT; | |
1182 | break; | |
1183 | } | |
1184 | ||
1185 | if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) { | |
1186 | ret = -EFAULT; | |
1187 | break; | |
1188 | } | |
1189 | ||
1190 | ret = io_submit_one(ctx, user_iocb, &tmp, compat); | |
1191 | if (ret) | |
1192 | break; | |
1193 | } | |
1194 | blk_finish_plug(&plug); | |
1195 | ||
1196 | put_ioctx(ctx); | |
1197 | return i ? i : ret; | |
1198 | } | |
1199 | ||
1200 | /* sys_io_submit: | |
1201 | * Queue the nr iocbs pointed to by iocbpp for processing. Returns | |
1202 | * the number of iocbs queued. May return -EINVAL if the aio_context | |
1203 | * specified by ctx_id is invalid, if nr is < 0, if the iocb at | |
1204 | * *iocbpp[0] is not properly initialized, if the operation specified | |
1205 | * is invalid for the file descriptor in the iocb. May fail with | |
1206 | * -EFAULT if any of the data structures point to invalid data. May | |
1207 | * fail with -EBADF if the file descriptor specified in the first | |
1208 | * iocb is invalid. May fail with -EAGAIN if insufficient resources | |
1209 | * are available to queue any iocbs. Will return 0 if nr is 0. Will | |
1210 | * fail with -ENOSYS if not implemented. | |
1211 | */ | |
1212 | SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr, | |
1213 | struct iocb __user * __user *, iocbpp) | |
1214 | { | |
1215 | return do_io_submit(ctx_id, nr, iocbpp, 0); | |
1216 | } | |
1217 | ||
1218 | /* lookup_kiocb | |
1219 | * Finds a given iocb for cancellation. | |
1220 | */ | |
1221 | static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, | |
1222 | u32 key) | |
1223 | { | |
1224 | struct list_head *pos; | |
1225 | ||
1226 | assert_spin_locked(&ctx->ctx_lock); | |
1227 | ||
1228 | if (key != KIOCB_KEY) | |
1229 | return NULL; | |
1230 | ||
1231 | /* TODO: use a hash or array, this sucks. */ | |
1232 | list_for_each(pos, &ctx->active_reqs) { | |
1233 | struct kiocb *kiocb = list_kiocb(pos); | |
1234 | if (kiocb->ki_obj.user == iocb) | |
1235 | return kiocb; | |
1236 | } | |
1237 | return NULL; | |
1238 | } | |
1239 | ||
1240 | /* sys_io_cancel: | |
1241 | * Attempts to cancel an iocb previously passed to io_submit. If | |
1242 | * the operation is successfully cancelled, the resulting event is | |
1243 | * copied into the memory pointed to by result without being placed | |
1244 | * into the completion queue and 0 is returned. May fail with | |
1245 | * -EFAULT if any of the data structures pointed to are invalid. | |
1246 | * May fail with -EINVAL if aio_context specified by ctx_id is | |
1247 | * invalid. May fail with -EAGAIN if the iocb specified was not | |
1248 | * cancelled. Will fail with -ENOSYS if not implemented. | |
1249 | */ | |
1250 | SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb, | |
1251 | struct io_event __user *, result) | |
1252 | { | |
1253 | struct io_event res; | |
1254 | struct kioctx *ctx; | |
1255 | struct kiocb *kiocb; | |
1256 | u32 key; | |
1257 | int ret; | |
1258 | ||
1259 | ret = get_user(key, &iocb->aio_key); | |
1260 | if (unlikely(ret)) | |
1261 | return -EFAULT; | |
1262 | ||
1263 | ctx = lookup_ioctx(ctx_id); | |
1264 | if (unlikely(!ctx)) | |
1265 | return -EINVAL; | |
1266 | ||
1267 | spin_lock_irq(&ctx->ctx_lock); | |
1268 | ||
1269 | kiocb = lookup_kiocb(ctx, iocb, key); | |
1270 | if (kiocb) | |
1271 | ret = kiocb_cancel(ctx, kiocb, &res); | |
1272 | else | |
1273 | ret = -EINVAL; | |
1274 | ||
1275 | spin_unlock_irq(&ctx->ctx_lock); | |
1276 | ||
1277 | if (!ret) { | |
1278 | /* Cancellation succeeded -- copy the result | |
1279 | * into the user's buffer. | |
1280 | */ | |
1281 | if (copy_to_user(result, &res, sizeof(res))) | |
1282 | ret = -EFAULT; | |
1283 | } | |
1284 | ||
1285 | put_ioctx(ctx); | |
1286 | ||
1287 | return ret; | |
1288 | } | |
1289 | ||
1290 | /* io_getevents: | |
1291 | * Attempts to read at least min_nr events and up to nr events from | |
1292 | * the completion queue for the aio_context specified by ctx_id. If | |
1293 | * it succeeds, the number of read events is returned. May fail with | |
1294 | * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is | |
1295 | * out of range, if timeout is out of range. May fail with -EFAULT | |
1296 | * if any of the memory specified is invalid. May return 0 or | |
1297 | * < min_nr if the timeout specified by timeout has elapsed | |
1298 | * before sufficient events are available, where timeout == NULL | |
1299 | * specifies an infinite timeout. Note that the timeout pointed to by | |
1300 | * timeout is relative. Will fail with -ENOSYS if not implemented. | |
1301 | */ | |
1302 | SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id, | |
1303 | long, min_nr, | |
1304 | long, nr, | |
1305 | struct io_event __user *, events, | |
1306 | struct timespec __user *, timeout) | |
1307 | { | |
1308 | struct kioctx *ioctx = lookup_ioctx(ctx_id); | |
1309 | long ret = -EINVAL; | |
1310 | ||
1311 | if (likely(ioctx)) { | |
1312 | if (likely(min_nr <= nr && min_nr >= 0)) | |
1313 | ret = read_events(ioctx, min_nr, nr, events, timeout); | |
1314 | put_ioctx(ioctx); | |
1315 | } | |
1316 | return ret; | |
1317 | } |