Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/fs/aio.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 44314 byte(s)
Tag kernel26-2.6.12-alx-r9
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 | /*------ sysctl variables----*/ |
44 | atomic_t aio_nr = ATOMIC_INIT(0); /* current system wide number of aio requests */ |
45 | unsigned aio_max_nr = 0x10000; /* system wide maximum number of aio requests */ |
46 | /*----end sysctl variables---*/ |
47 | |
48 | static kmem_cache_t *kiocb_cachep; |
49 | static kmem_cache_t *kioctx_cachep; |
50 | |
51 | static struct workqueue_struct *aio_wq; |
52 | |
53 | /* Used for rare fput completion. */ |
54 | static void aio_fput_routine(void *); |
55 | static DECLARE_WORK(fput_work, aio_fput_routine, NULL); |
56 | |
57 | static DEFINE_SPINLOCK(fput_lock); |
58 | static LIST_HEAD(fput_head); |
59 | |
60 | static void aio_kick_handler(void *); |
61 | |
62 | /* aio_setup |
63 | * Creates the slab caches used by the aio routines, panic on |
64 | * failure as this is done early during the boot sequence. |
65 | */ |
66 | static int __init aio_setup(void) |
67 | { |
68 | kiocb_cachep = kmem_cache_create("kiocb", sizeof(struct kiocb), |
69 | 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); |
70 | kioctx_cachep = kmem_cache_create("kioctx", sizeof(struct kioctx), |
71 | 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); |
72 | |
73 | aio_wq = create_workqueue("aio"); |
74 | |
75 | pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page)); |
76 | |
77 | return 0; |
78 | } |
79 | |
80 | static void aio_free_ring(struct kioctx *ctx) |
81 | { |
82 | struct aio_ring_info *info = &ctx->ring_info; |
83 | long i; |
84 | |
85 | for (i=0; i<info->nr_pages; i++) |
86 | put_page(info->ring_pages[i]); |
87 | |
88 | if (info->mmap_size) { |
89 | down_write(&ctx->mm->mmap_sem); |
90 | do_munmap(ctx->mm, info->mmap_base, info->mmap_size); |
91 | up_write(&ctx->mm->mmap_sem); |
92 | } |
93 | |
94 | if (info->ring_pages && info->ring_pages != info->internal_pages) |
95 | kfree(info->ring_pages); |
96 | info->ring_pages = NULL; |
97 | info->nr = 0; |
98 | } |
99 | |
100 | static int aio_setup_ring(struct kioctx *ctx) |
101 | { |
102 | struct aio_ring *ring; |
103 | struct aio_ring_info *info = &ctx->ring_info; |
104 | unsigned nr_events = ctx->max_reqs; |
105 | unsigned long size; |
106 | int nr_pages; |
107 | |
108 | /* Compensate for the ring buffer's head/tail overlap entry */ |
109 | nr_events += 2; /* 1 is required, 2 for good luck */ |
110 | |
111 | size = sizeof(struct aio_ring); |
112 | size += sizeof(struct io_event) * nr_events; |
113 | nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT; |
114 | |
115 | if (nr_pages < 0) |
116 | return -EINVAL; |
117 | |
118 | nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event); |
119 | |
120 | info->nr = 0; |
121 | info->ring_pages = info->internal_pages; |
122 | if (nr_pages > AIO_RING_PAGES) { |
123 | info->ring_pages = kmalloc(sizeof(struct page *) * nr_pages, GFP_KERNEL); |
124 | if (!info->ring_pages) |
125 | return -ENOMEM; |
126 | memset(info->ring_pages, 0, sizeof(struct page *) * nr_pages); |
127 | } |
128 | |
129 | info->mmap_size = nr_pages * PAGE_SIZE; |
130 | dprintk("attempting mmap of %lu bytes\n", info->mmap_size); |
131 | down_write(&ctx->mm->mmap_sem); |
132 | info->mmap_base = do_mmap(NULL, 0, info->mmap_size, |
133 | PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, |
134 | 0); |
135 | if (IS_ERR((void *)info->mmap_base)) { |
136 | up_write(&ctx->mm->mmap_sem); |
137 | printk("mmap err: %ld\n", -info->mmap_base); |
138 | info->mmap_size = 0; |
139 | aio_free_ring(ctx); |
140 | return -EAGAIN; |
141 | } |
142 | |
143 | dprintk("mmap address: 0x%08lx\n", info->mmap_base); |
144 | info->nr_pages = get_user_pages(current, ctx->mm, |
145 | info->mmap_base, nr_pages, |
146 | 1, 0, info->ring_pages, NULL); |
147 | up_write(&ctx->mm->mmap_sem); |
148 | |
149 | if (unlikely(info->nr_pages != nr_pages)) { |
150 | aio_free_ring(ctx); |
151 | return -EAGAIN; |
152 | } |
153 | |
154 | ctx->user_id = info->mmap_base; |
155 | |
156 | info->nr = nr_events; /* trusted copy */ |
157 | |
158 | ring = kmap_atomic(info->ring_pages[0], KM_USER0); |
159 | ring->nr = nr_events; /* user copy */ |
160 | ring->id = ctx->user_id; |
161 | ring->head = ring->tail = 0; |
162 | ring->magic = AIO_RING_MAGIC; |
163 | ring->compat_features = AIO_RING_COMPAT_FEATURES; |
164 | ring->incompat_features = AIO_RING_INCOMPAT_FEATURES; |
165 | ring->header_length = sizeof(struct aio_ring); |
166 | kunmap_atomic(ring, KM_USER0); |
167 | |
168 | return 0; |
169 | } |
170 | |
171 | |
172 | /* aio_ring_event: returns a pointer to the event at the given index from |
173 | * kmap_atomic(, km). Release the pointer with put_aio_ring_event(); |
174 | */ |
175 | #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event)) |
176 | #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event)) |
177 | #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE) |
178 | |
179 | #define aio_ring_event(info, nr, km) ({ \ |
180 | unsigned pos = (nr) + AIO_EVENTS_OFFSET; \ |
181 | struct io_event *__event; \ |
182 | __event = kmap_atomic( \ |
183 | (info)->ring_pages[pos / AIO_EVENTS_PER_PAGE], km); \ |
184 | __event += pos % AIO_EVENTS_PER_PAGE; \ |
185 | __event; \ |
186 | }) |
187 | |
188 | #define put_aio_ring_event(event, km) do { \ |
189 | struct io_event *__event = (event); \ |
190 | (void)__event; \ |
191 | kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK), km); \ |
192 | } while(0) |
193 | |
194 | /* ioctx_alloc |
195 | * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed. |
196 | */ |
197 | static struct kioctx *ioctx_alloc(unsigned nr_events) |
198 | { |
199 | struct mm_struct *mm; |
200 | struct kioctx *ctx; |
201 | |
202 | /* Prevent overflows */ |
203 | if ((nr_events > (0x10000000U / sizeof(struct io_event))) || |
204 | (nr_events > (0x10000000U / sizeof(struct kiocb)))) { |
205 | pr_debug("ENOMEM: nr_events too high\n"); |
206 | return ERR_PTR(-EINVAL); |
207 | } |
208 | |
209 | if (nr_events > aio_max_nr) |
210 | return ERR_PTR(-EAGAIN); |
211 | |
212 | ctx = kmem_cache_alloc(kioctx_cachep, GFP_KERNEL); |
213 | if (!ctx) |
214 | return ERR_PTR(-ENOMEM); |
215 | |
216 | memset(ctx, 0, sizeof(*ctx)); |
217 | ctx->max_reqs = nr_events; |
218 | mm = ctx->mm = current->mm; |
219 | atomic_inc(&mm->mm_count); |
220 | |
221 | atomic_set(&ctx->users, 1); |
222 | spin_lock_init(&ctx->ctx_lock); |
223 | spin_lock_init(&ctx->ring_info.ring_lock); |
224 | init_waitqueue_head(&ctx->wait); |
225 | |
226 | INIT_LIST_HEAD(&ctx->active_reqs); |
227 | INIT_LIST_HEAD(&ctx->run_list); |
228 | INIT_WORK(&ctx->wq, aio_kick_handler, ctx); |
229 | |
230 | if (aio_setup_ring(ctx) < 0) |
231 | goto out_freectx; |
232 | |
233 | /* limit the number of system wide aios */ |
234 | atomic_add(ctx->max_reqs, &aio_nr); /* undone by __put_ioctx */ |
235 | if (unlikely(atomic_read(&aio_nr) > aio_max_nr)) |
236 | goto out_cleanup; |
237 | |
238 | /* now link into global list. kludge. FIXME */ |
239 | write_lock(&mm->ioctx_list_lock); |
240 | ctx->next = mm->ioctx_list; |
241 | mm->ioctx_list = ctx; |
242 | write_unlock(&mm->ioctx_list_lock); |
243 | |
244 | dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n", |
245 | ctx, ctx->user_id, current->mm, ctx->ring_info.nr); |
246 | return ctx; |
247 | |
248 | out_cleanup: |
249 | atomic_sub(ctx->max_reqs, &aio_nr); |
250 | ctx->max_reqs = 0; /* prevent __put_ioctx from sub'ing aio_nr */ |
251 | __put_ioctx(ctx); |
252 | return ERR_PTR(-EAGAIN); |
253 | |
254 | out_freectx: |
255 | mmdrop(mm); |
256 | kmem_cache_free(kioctx_cachep, ctx); |
257 | ctx = ERR_PTR(-ENOMEM); |
258 | |
259 | dprintk("aio: error allocating ioctx %p\n", ctx); |
260 | return ctx; |
261 | } |
262 | |
263 | /* aio_cancel_all |
264 | * Cancels all outstanding aio requests on an aio context. Used |
265 | * when the processes owning a context have all exited to encourage |
266 | * the rapid destruction of the kioctx. |
267 | */ |
268 | static void aio_cancel_all(struct kioctx *ctx) |
269 | { |
270 | int (*cancel)(struct kiocb *, struct io_event *); |
271 | struct io_event res; |
272 | spin_lock_irq(&ctx->ctx_lock); |
273 | ctx->dead = 1; |
274 | while (!list_empty(&ctx->active_reqs)) { |
275 | struct list_head *pos = ctx->active_reqs.next; |
276 | struct kiocb *iocb = list_kiocb(pos); |
277 | list_del_init(&iocb->ki_list); |
278 | cancel = iocb->ki_cancel; |
279 | kiocbSetCancelled(iocb); |
280 | if (cancel) { |
281 | iocb->ki_users++; |
282 | spin_unlock_irq(&ctx->ctx_lock); |
283 | cancel(iocb, &res); |
284 | spin_lock_irq(&ctx->ctx_lock); |
285 | } |
286 | } |
287 | spin_unlock_irq(&ctx->ctx_lock); |
288 | } |
289 | |
290 | static void wait_for_all_aios(struct kioctx *ctx) |
291 | { |
292 | struct task_struct *tsk = current; |
293 | DECLARE_WAITQUEUE(wait, tsk); |
294 | |
295 | if (!ctx->reqs_active) |
296 | return; |
297 | |
298 | add_wait_queue(&ctx->wait, &wait); |
299 | set_task_state(tsk, TASK_UNINTERRUPTIBLE); |
300 | while (ctx->reqs_active) { |
301 | schedule(); |
302 | set_task_state(tsk, TASK_UNINTERRUPTIBLE); |
303 | } |
304 | __set_task_state(tsk, TASK_RUNNING); |
305 | remove_wait_queue(&ctx->wait, &wait); |
306 | } |
307 | |
308 | /* wait_on_sync_kiocb: |
309 | * Waits on the given sync kiocb to complete. |
310 | */ |
311 | ssize_t fastcall wait_on_sync_kiocb(struct kiocb *iocb) |
312 | { |
313 | while (iocb->ki_users) { |
314 | set_current_state(TASK_UNINTERRUPTIBLE); |
315 | if (!iocb->ki_users) |
316 | break; |
317 | schedule(); |
318 | } |
319 | __set_current_state(TASK_RUNNING); |
320 | return iocb->ki_user_data; |
321 | } |
322 | |
323 | /* exit_aio: called when the last user of mm goes away. At this point, |
324 | * there is no way for any new requests to be submited or any of the |
325 | * io_* syscalls to be called on the context. However, there may be |
326 | * outstanding requests which hold references to the context; as they |
327 | * go away, they will call put_ioctx and release any pinned memory |
328 | * associated with the request (held via struct page * references). |
329 | */ |
330 | void fastcall exit_aio(struct mm_struct *mm) |
331 | { |
332 | struct kioctx *ctx = mm->ioctx_list; |
333 | mm->ioctx_list = NULL; |
334 | while (ctx) { |
335 | struct kioctx *next = ctx->next; |
336 | ctx->next = NULL; |
337 | aio_cancel_all(ctx); |
338 | |
339 | wait_for_all_aios(ctx); |
340 | /* |
341 | * this is an overkill, but ensures we don't leave |
342 | * the ctx on the aio_wq |
343 | */ |
344 | flush_workqueue(aio_wq); |
345 | |
346 | if (1 != atomic_read(&ctx->users)) |
347 | printk(KERN_DEBUG |
348 | "exit_aio:ioctx still alive: %d %d %d\n", |
349 | atomic_read(&ctx->users), ctx->dead, |
350 | ctx->reqs_active); |
351 | put_ioctx(ctx); |
352 | ctx = next; |
353 | } |
354 | } |
355 | |
356 | /* __put_ioctx |
357 | * Called when the last user of an aio context has gone away, |
358 | * and the struct needs to be freed. |
359 | */ |
360 | void fastcall __put_ioctx(struct kioctx *ctx) |
361 | { |
362 | unsigned nr_events = ctx->max_reqs; |
363 | |
364 | if (unlikely(ctx->reqs_active)) |
365 | BUG(); |
366 | |
367 | cancel_delayed_work(&ctx->wq); |
368 | flush_workqueue(aio_wq); |
369 | aio_free_ring(ctx); |
370 | mmdrop(ctx->mm); |
371 | ctx->mm = NULL; |
372 | pr_debug("__put_ioctx: freeing %p\n", ctx); |
373 | kmem_cache_free(kioctx_cachep, ctx); |
374 | |
375 | atomic_sub(nr_events, &aio_nr); |
376 | } |
377 | |
378 | /* aio_get_req |
379 | * Allocate a slot for an aio request. Increments the users count |
380 | * of the kioctx so that the kioctx stays around until all requests are |
381 | * complete. Returns NULL if no requests are free. |
382 | * |
383 | * Returns with kiocb->users set to 2. The io submit code path holds |
384 | * an extra reference while submitting the i/o. |
385 | * This prevents races between the aio code path referencing the |
386 | * req (after submitting it) and aio_complete() freeing the req. |
387 | */ |
388 | static struct kiocb *FASTCALL(__aio_get_req(struct kioctx *ctx)); |
389 | static struct kiocb fastcall *__aio_get_req(struct kioctx *ctx) |
390 | { |
391 | struct kiocb *req = NULL; |
392 | struct aio_ring *ring; |
393 | int okay = 0; |
394 | |
395 | req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL); |
396 | if (unlikely(!req)) |
397 | return NULL; |
398 | |
399 | req->ki_flags = 1 << KIF_LOCKED; |
400 | req->ki_users = 2; |
401 | req->ki_key = 0; |
402 | req->ki_ctx = ctx; |
403 | req->ki_cancel = NULL; |
404 | req->ki_retry = NULL; |
405 | req->ki_dtor = NULL; |
406 | req->private = NULL; |
407 | INIT_LIST_HEAD(&req->ki_run_list); |
408 | |
409 | /* Check if the completion queue has enough free space to |
410 | * accept an event from this io. |
411 | */ |
412 | spin_lock_irq(&ctx->ctx_lock); |
413 | ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0); |
414 | if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) { |
415 | list_add(&req->ki_list, &ctx->active_reqs); |
416 | get_ioctx(ctx); |
417 | ctx->reqs_active++; |
418 | okay = 1; |
419 | } |
420 | kunmap_atomic(ring, KM_USER0); |
421 | spin_unlock_irq(&ctx->ctx_lock); |
422 | |
423 | if (!okay) { |
424 | kmem_cache_free(kiocb_cachep, req); |
425 | req = NULL; |
426 | } |
427 | |
428 | return req; |
429 | } |
430 | |
431 | static inline struct kiocb *aio_get_req(struct kioctx *ctx) |
432 | { |
433 | struct kiocb *req; |
434 | /* Handle a potential starvation case -- should be exceedingly rare as |
435 | * requests will be stuck on fput_head only if the aio_fput_routine is |
436 | * delayed and the requests were the last user of the struct file. |
437 | */ |
438 | req = __aio_get_req(ctx); |
439 | if (unlikely(NULL == req)) { |
440 | aio_fput_routine(NULL); |
441 | req = __aio_get_req(ctx); |
442 | } |
443 | return req; |
444 | } |
445 | |
446 | static inline void really_put_req(struct kioctx *ctx, struct kiocb *req) |
447 | { |
448 | if (req->ki_dtor) |
449 | req->ki_dtor(req); |
450 | kmem_cache_free(kiocb_cachep, req); |
451 | ctx->reqs_active--; |
452 | |
453 | if (unlikely(!ctx->reqs_active && ctx->dead)) |
454 | wake_up(&ctx->wait); |
455 | } |
456 | |
457 | static void aio_fput_routine(void *data) |
458 | { |
459 | spin_lock_irq(&fput_lock); |
460 | while (likely(!list_empty(&fput_head))) { |
461 | struct kiocb *req = list_kiocb(fput_head.next); |
462 | struct kioctx *ctx = req->ki_ctx; |
463 | |
464 | list_del(&req->ki_list); |
465 | spin_unlock_irq(&fput_lock); |
466 | |
467 | /* Complete the fput */ |
468 | __fput(req->ki_filp); |
469 | |
470 | /* Link the iocb into the context's free list */ |
471 | spin_lock_irq(&ctx->ctx_lock); |
472 | really_put_req(ctx, req); |
473 | spin_unlock_irq(&ctx->ctx_lock); |
474 | |
475 | put_ioctx(ctx); |
476 | spin_lock_irq(&fput_lock); |
477 | } |
478 | spin_unlock_irq(&fput_lock); |
479 | } |
480 | |
481 | /* __aio_put_req |
482 | * Returns true if this put was the last user of the request. |
483 | */ |
484 | static int __aio_put_req(struct kioctx *ctx, struct kiocb *req) |
485 | { |
486 | dprintk(KERN_DEBUG "aio_put(%p): f_count=%d\n", |
487 | req, atomic_read(&req->ki_filp->f_count)); |
488 | |
489 | req->ki_users --; |
490 | if (unlikely(req->ki_users < 0)) |
491 | BUG(); |
492 | if (likely(req->ki_users)) |
493 | return 0; |
494 | list_del(&req->ki_list); /* remove from active_reqs */ |
495 | req->ki_cancel = NULL; |
496 | req->ki_retry = NULL; |
497 | |
498 | /* Must be done under the lock to serialise against cancellation. |
499 | * Call this aio_fput as it duplicates fput via the fput_work. |
500 | */ |
501 | if (unlikely(atomic_dec_and_test(&req->ki_filp->f_count))) { |
502 | get_ioctx(ctx); |
503 | spin_lock(&fput_lock); |
504 | list_add(&req->ki_list, &fput_head); |
505 | spin_unlock(&fput_lock); |
506 | queue_work(aio_wq, &fput_work); |
507 | } else |
508 | really_put_req(ctx, req); |
509 | return 1; |
510 | } |
511 | |
512 | /* aio_put_req |
513 | * Returns true if this put was the last user of the kiocb, |
514 | * false if the request is still in use. |
515 | */ |
516 | int fastcall aio_put_req(struct kiocb *req) |
517 | { |
518 | struct kioctx *ctx = req->ki_ctx; |
519 | int ret; |
520 | spin_lock_irq(&ctx->ctx_lock); |
521 | ret = __aio_put_req(ctx, req); |
522 | spin_unlock_irq(&ctx->ctx_lock); |
523 | if (ret) |
524 | put_ioctx(ctx); |
525 | return ret; |
526 | } |
527 | |
528 | /* Lookup an ioctx id. ioctx_list is lockless for reads. |
529 | * FIXME: this is O(n) and is only suitable for development. |
530 | */ |
531 | struct kioctx *lookup_ioctx(unsigned long ctx_id) |
532 | { |
533 | struct kioctx *ioctx; |
534 | struct mm_struct *mm; |
535 | |
536 | mm = current->mm; |
537 | read_lock(&mm->ioctx_list_lock); |
538 | for (ioctx = mm->ioctx_list; ioctx; ioctx = ioctx->next) |
539 | if (likely(ioctx->user_id == ctx_id && !ioctx->dead)) { |
540 | get_ioctx(ioctx); |
541 | break; |
542 | } |
543 | read_unlock(&mm->ioctx_list_lock); |
544 | |
545 | return ioctx; |
546 | } |
547 | |
548 | /* |
549 | * use_mm |
550 | * Makes the calling kernel thread take on the specified |
551 | * mm context. |
552 | * Called by the retry thread execute retries within the |
553 | * iocb issuer's mm context, so that copy_from/to_user |
554 | * operations work seamlessly for aio. |
555 | * (Note: this routine is intended to be called only |
556 | * from a kernel thread context) |
557 | */ |
558 | static void use_mm(struct mm_struct *mm) |
559 | { |
560 | struct mm_struct *active_mm; |
561 | struct task_struct *tsk = current; |
562 | |
563 | task_lock(tsk); |
564 | tsk->flags |= PF_BORROWED_MM; |
565 | active_mm = tsk->active_mm; |
566 | atomic_inc(&mm->mm_count); |
567 | tsk->mm = mm; |
568 | tsk->active_mm = mm; |
569 | activate_mm(active_mm, mm); |
570 | task_unlock(tsk); |
571 | |
572 | mmdrop(active_mm); |
573 | } |
574 | |
575 | /* |
576 | * unuse_mm |
577 | * Reverses the effect of use_mm, i.e. releases the |
578 | * specified mm context which was earlier taken on |
579 | * by the calling kernel thread |
580 | * (Note: this routine is intended to be called only |
581 | * from a kernel thread context) |
582 | * |
583 | * Comments: Called with ctx->ctx_lock held. This nests |
584 | * task_lock instead ctx_lock. |
585 | */ |
586 | static void unuse_mm(struct mm_struct *mm) |
587 | { |
588 | struct task_struct *tsk = current; |
589 | |
590 | task_lock(tsk); |
591 | tsk->flags &= ~PF_BORROWED_MM; |
592 | tsk->mm = NULL; |
593 | /* active_mm is still 'mm' */ |
594 | enter_lazy_tlb(mm, tsk); |
595 | task_unlock(tsk); |
596 | } |
597 | |
598 | /* |
599 | * Queue up a kiocb to be retried. Assumes that the kiocb |
600 | * has already been marked as kicked, and places it on |
601 | * the retry run list for the corresponding ioctx, if it |
602 | * isn't already queued. Returns 1 if it actually queued |
603 | * the kiocb (to tell the caller to activate the work |
604 | * queue to process it), or 0, if it found that it was |
605 | * already queued. |
606 | * |
607 | * Should be called with the spin lock iocb->ki_ctx->ctx_lock |
608 | * held |
609 | */ |
610 | static inline int __queue_kicked_iocb(struct kiocb *iocb) |
611 | { |
612 | struct kioctx *ctx = iocb->ki_ctx; |
613 | |
614 | if (list_empty(&iocb->ki_run_list)) { |
615 | list_add_tail(&iocb->ki_run_list, |
616 | &ctx->run_list); |
617 | return 1; |
618 | } |
619 | return 0; |
620 | } |
621 | |
622 | /* aio_run_iocb |
623 | * This is the core aio execution routine. It is |
624 | * invoked both for initial i/o submission and |
625 | * subsequent retries via the aio_kick_handler. |
626 | * Expects to be invoked with iocb->ki_ctx->lock |
627 | * already held. The lock is released and reaquired |
628 | * as needed during processing. |
629 | * |
630 | * Calls the iocb retry method (already setup for the |
631 | * iocb on initial submission) for operation specific |
632 | * handling, but takes care of most of common retry |
633 | * execution details for a given iocb. The retry method |
634 | * needs to be non-blocking as far as possible, to avoid |
635 | * holding up other iocbs waiting to be serviced by the |
636 | * retry kernel thread. |
637 | * |
638 | * The trickier parts in this code have to do with |
639 | * ensuring that only one retry instance is in progress |
640 | * for a given iocb at any time. Providing that guarantee |
641 | * simplifies the coding of individual aio operations as |
642 | * it avoids various potential races. |
643 | */ |
644 | static ssize_t aio_run_iocb(struct kiocb *iocb) |
645 | { |
646 | struct kioctx *ctx = iocb->ki_ctx; |
647 | ssize_t (*retry)(struct kiocb *); |
648 | ssize_t ret; |
649 | |
650 | if (iocb->ki_retried++ > 1024*1024) { |
651 | printk("Maximal retry count. Bytes done %Zd\n", |
652 | iocb->ki_nbytes - iocb->ki_left); |
653 | return -EAGAIN; |
654 | } |
655 | |
656 | if (!(iocb->ki_retried & 0xff)) { |
657 | pr_debug("%ld retry: %d of %d\n", iocb->ki_retried, |
658 | iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes); |
659 | } |
660 | |
661 | if (!(retry = iocb->ki_retry)) { |
662 | printk("aio_run_iocb: iocb->ki_retry = NULL\n"); |
663 | return 0; |
664 | } |
665 | |
666 | /* |
667 | * We don't want the next retry iteration for this |
668 | * operation to start until this one has returned and |
669 | * updated the iocb state. However, wait_queue functions |
670 | * can trigger a kick_iocb from interrupt context in the |
671 | * meantime, indicating that data is available for the next |
672 | * iteration. We want to remember that and enable the |
673 | * next retry iteration _after_ we are through with |
674 | * this one. |
675 | * |
676 | * So, in order to be able to register a "kick", but |
677 | * prevent it from being queued now, we clear the kick |
678 | * flag, but make the kick code *think* that the iocb is |
679 | * still on the run list until we are actually done. |
680 | * When we are done with this iteration, we check if |
681 | * the iocb was kicked in the meantime and if so, queue |
682 | * it up afresh. |
683 | */ |
684 | |
685 | kiocbClearKicked(iocb); |
686 | |
687 | /* |
688 | * This is so that aio_complete knows it doesn't need to |
689 | * pull the iocb off the run list (We can't just call |
690 | * INIT_LIST_HEAD because we don't want a kick_iocb to |
691 | * queue this on the run list yet) |
692 | */ |
693 | iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL; |
694 | spin_unlock_irq(&ctx->ctx_lock); |
695 | |
696 | /* Quit retrying if the i/o has been cancelled */ |
697 | if (kiocbIsCancelled(iocb)) { |
698 | ret = -EINTR; |
699 | aio_complete(iocb, ret, 0); |
700 | /* must not access the iocb after this */ |
701 | goto out; |
702 | } |
703 | |
704 | /* |
705 | * Now we are all set to call the retry method in async |
706 | * context. By setting this thread's io_wait context |
707 | * to point to the wait queue entry inside the currently |
708 | * running iocb for the duration of the retry, we ensure |
709 | * that async notification wakeups are queued by the |
710 | * operation instead of blocking waits, and when notified, |
711 | * cause the iocb to be kicked for continuation (through |
712 | * the aio_wake_function callback). |
713 | */ |
714 | BUG_ON(current->io_wait != NULL); |
715 | current->io_wait = &iocb->ki_wait; |
716 | ret = retry(iocb); |
717 | current->io_wait = NULL; |
718 | |
719 | if (-EIOCBRETRY != ret) { |
720 | if (-EIOCBQUEUED != ret) { |
721 | BUG_ON(!list_empty(&iocb->ki_wait.task_list)); |
722 | aio_complete(iocb, ret, 0); |
723 | /* must not access the iocb after this */ |
724 | } |
725 | } else { |
726 | /* |
727 | * Issue an additional retry to avoid waiting forever if |
728 | * no waits were queued (e.g. in case of a short read). |
729 | */ |
730 | if (list_empty(&iocb->ki_wait.task_list)) |
731 | kiocbSetKicked(iocb); |
732 | } |
733 | out: |
734 | spin_lock_irq(&ctx->ctx_lock); |
735 | |
736 | if (-EIOCBRETRY == ret) { |
737 | /* |
738 | * OK, now that we are done with this iteration |
739 | * and know that there is more left to go, |
740 | * this is where we let go so that a subsequent |
741 | * "kick" can start the next iteration |
742 | */ |
743 | |
744 | /* will make __queue_kicked_iocb succeed from here on */ |
745 | INIT_LIST_HEAD(&iocb->ki_run_list); |
746 | /* we must queue the next iteration ourselves, if it |
747 | * has already been kicked */ |
748 | if (kiocbIsKicked(iocb)) { |
749 | __queue_kicked_iocb(iocb); |
750 | } |
751 | } |
752 | return ret; |
753 | } |
754 | |
755 | /* |
756 | * __aio_run_iocbs: |
757 | * Process all pending retries queued on the ioctx |
758 | * run list. |
759 | * Assumes it is operating within the aio issuer's mm |
760 | * context. Expects to be called with ctx->ctx_lock held |
761 | */ |
762 | static int __aio_run_iocbs(struct kioctx *ctx) |
763 | { |
764 | struct kiocb *iocb; |
765 | LIST_HEAD(run_list); |
766 | |
767 | list_splice_init(&ctx->run_list, &run_list); |
768 | while (!list_empty(&run_list)) { |
769 | iocb = list_entry(run_list.next, struct kiocb, |
770 | ki_run_list); |
771 | list_del(&iocb->ki_run_list); |
772 | /* |
773 | * Hold an extra reference while retrying i/o. |
774 | */ |
775 | iocb->ki_users++; /* grab extra reference */ |
776 | aio_run_iocb(iocb); |
777 | if (__aio_put_req(ctx, iocb)) /* drop extra ref */ |
778 | put_ioctx(ctx); |
779 | } |
780 | if (!list_empty(&ctx->run_list)) |
781 | return 1; |
782 | return 0; |
783 | } |
784 | |
785 | static void aio_queue_work(struct kioctx * ctx) |
786 | { |
787 | unsigned long timeout; |
788 | /* |
789 | * if someone is waiting, get the work started right |
790 | * away, otherwise, use a longer delay |
791 | */ |
792 | smp_mb(); |
793 | if (waitqueue_active(&ctx->wait)) |
794 | timeout = 1; |
795 | else |
796 | timeout = HZ/10; |
797 | queue_delayed_work(aio_wq, &ctx->wq, timeout); |
798 | } |
799 | |
800 | |
801 | /* |
802 | * aio_run_iocbs: |
803 | * Process all pending retries queued on the ioctx |
804 | * run list. |
805 | * Assumes it is operating within the aio issuer's mm |
806 | * context. |
807 | */ |
808 | static inline void aio_run_iocbs(struct kioctx *ctx) |
809 | { |
810 | int requeue; |
811 | |
812 | spin_lock_irq(&ctx->ctx_lock); |
813 | |
814 | requeue = __aio_run_iocbs(ctx); |
815 | spin_unlock_irq(&ctx->ctx_lock); |
816 | if (requeue) |
817 | aio_queue_work(ctx); |
818 | } |
819 | |
820 | /* |
821 | * just like aio_run_iocbs, but keeps running them until |
822 | * the list stays empty |
823 | */ |
824 | static inline void aio_run_all_iocbs(struct kioctx *ctx) |
825 | { |
826 | spin_lock_irq(&ctx->ctx_lock); |
827 | while (__aio_run_iocbs(ctx)) |
828 | ; |
829 | spin_unlock_irq(&ctx->ctx_lock); |
830 | } |
831 | |
832 | /* |
833 | * aio_kick_handler: |
834 | * Work queue handler triggered to process pending |
835 | * retries on an ioctx. Takes on the aio issuer's |
836 | * mm context before running the iocbs, so that |
837 | * copy_xxx_user operates on the issuer's address |
838 | * space. |
839 | * Run on aiod's context. |
840 | */ |
841 | static void aio_kick_handler(void *data) |
842 | { |
843 | struct kioctx *ctx = data; |
844 | mm_segment_t oldfs = get_fs(); |
845 | int requeue; |
846 | |
847 | set_fs(USER_DS); |
848 | use_mm(ctx->mm); |
849 | spin_lock_irq(&ctx->ctx_lock); |
850 | requeue =__aio_run_iocbs(ctx); |
851 | unuse_mm(ctx->mm); |
852 | spin_unlock_irq(&ctx->ctx_lock); |
853 | set_fs(oldfs); |
854 | /* |
855 | * we're in a worker thread already, don't use queue_delayed_work, |
856 | */ |
857 | if (requeue) |
858 | queue_work(aio_wq, &ctx->wq); |
859 | } |
860 | |
861 | |
862 | /* |
863 | * Called by kick_iocb to queue the kiocb for retry |
864 | * and if required activate the aio work queue to process |
865 | * it |
866 | */ |
867 | static void queue_kicked_iocb(struct kiocb *iocb) |
868 | { |
869 | struct kioctx *ctx = iocb->ki_ctx; |
870 | unsigned long flags; |
871 | int run = 0; |
872 | |
873 | WARN_ON((!list_empty(&iocb->ki_wait.task_list))); |
874 | |
875 | spin_lock_irqsave(&ctx->ctx_lock, flags); |
876 | run = __queue_kicked_iocb(iocb); |
877 | spin_unlock_irqrestore(&ctx->ctx_lock, flags); |
878 | if (run) |
879 | aio_queue_work(ctx); |
880 | } |
881 | |
882 | /* |
883 | * kick_iocb: |
884 | * Called typically from a wait queue callback context |
885 | * (aio_wake_function) to trigger a retry of the iocb. |
886 | * The retry is usually executed by aio workqueue |
887 | * threads (See aio_kick_handler). |
888 | */ |
889 | void fastcall kick_iocb(struct kiocb *iocb) |
890 | { |
891 | /* sync iocbs are easy: they can only ever be executing from a |
892 | * single context. */ |
893 | if (is_sync_kiocb(iocb)) { |
894 | kiocbSetKicked(iocb); |
895 | wake_up_process(iocb->ki_obj.tsk); |
896 | return; |
897 | } |
898 | |
899 | /* If its already kicked we shouldn't queue it again */ |
900 | if (!kiocbTryKick(iocb)) { |
901 | queue_kicked_iocb(iocb); |
902 | } |
903 | } |
904 | EXPORT_SYMBOL(kick_iocb); |
905 | |
906 | /* aio_complete |
907 | * Called when the io request on the given iocb is complete. |
908 | * Returns true if this is the last user of the request. The |
909 | * only other user of the request can be the cancellation code. |
910 | */ |
911 | int fastcall aio_complete(struct kiocb *iocb, long res, long res2) |
912 | { |
913 | struct kioctx *ctx = iocb->ki_ctx; |
914 | struct aio_ring_info *info; |
915 | struct aio_ring *ring; |
916 | struct io_event *event; |
917 | unsigned long flags; |
918 | unsigned long tail; |
919 | int ret; |
920 | |
921 | /* Special case handling for sync iocbs: events go directly |
922 | * into the iocb for fast handling. Note that this will not |
923 | * work if we allow sync kiocbs to be cancelled. in which |
924 | * case the usage count checks will have to move under ctx_lock |
925 | * for all cases. |
926 | */ |
927 | if (is_sync_kiocb(iocb)) { |
928 | int ret; |
929 | |
930 | iocb->ki_user_data = res; |
931 | if (iocb->ki_users == 1) { |
932 | iocb->ki_users = 0; |
933 | ret = 1; |
934 | } else { |
935 | spin_lock_irq(&ctx->ctx_lock); |
936 | iocb->ki_users--; |
937 | ret = (0 == iocb->ki_users); |
938 | spin_unlock_irq(&ctx->ctx_lock); |
939 | } |
940 | /* sync iocbs put the task here for us */ |
941 | wake_up_process(iocb->ki_obj.tsk); |
942 | return ret; |
943 | } |
944 | |
945 | info = &ctx->ring_info; |
946 | |
947 | /* add a completion event to the ring buffer. |
948 | * must be done holding ctx->ctx_lock to prevent |
949 | * other code from messing with the tail |
950 | * pointer since we might be called from irq |
951 | * context. |
952 | */ |
953 | spin_lock_irqsave(&ctx->ctx_lock, flags); |
954 | |
955 | if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list)) |
956 | list_del_init(&iocb->ki_run_list); |
957 | |
958 | /* |
959 | * cancelled requests don't get events, userland was given one |
960 | * when the event got cancelled. |
961 | */ |
962 | if (kiocbIsCancelled(iocb)) |
963 | goto put_rq; |
964 | |
965 | ring = kmap_atomic(info->ring_pages[0], KM_IRQ1); |
966 | |
967 | tail = info->tail; |
968 | event = aio_ring_event(info, tail, KM_IRQ0); |
969 | if (++tail >= info->nr) |
970 | tail = 0; |
971 | |
972 | event->obj = (u64)(unsigned long)iocb->ki_obj.user; |
973 | event->data = iocb->ki_user_data; |
974 | event->res = res; |
975 | event->res2 = res2; |
976 | |
977 | dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n", |
978 | ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data, |
979 | res, res2); |
980 | |
981 | /* after flagging the request as done, we |
982 | * must never even look at it again |
983 | */ |
984 | smp_wmb(); /* make event visible before updating tail */ |
985 | |
986 | info->tail = tail; |
987 | ring->tail = tail; |
988 | |
989 | put_aio_ring_event(event, KM_IRQ0); |
990 | kunmap_atomic(ring, KM_IRQ1); |
991 | |
992 | pr_debug("added to ring %p at [%lu]\n", iocb, tail); |
993 | |
994 | pr_debug("%ld retries: %d of %d\n", iocb->ki_retried, |
995 | iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes); |
996 | put_rq: |
997 | /* everything turned out well, dispose of the aiocb. */ |
998 | ret = __aio_put_req(ctx, iocb); |
999 | |
1000 | spin_unlock_irqrestore(&ctx->ctx_lock, flags); |
1001 | |
1002 | if (waitqueue_active(&ctx->wait)) |
1003 | wake_up(&ctx->wait); |
1004 | |
1005 | if (ret) |
1006 | put_ioctx(ctx); |
1007 | |
1008 | return ret; |
1009 | } |
1010 | |
1011 | /* aio_read_evt |
1012 | * Pull an event off of the ioctx's event ring. Returns the number of |
1013 | * events fetched (0 or 1 ;-) |
1014 | * FIXME: make this use cmpxchg. |
1015 | * TODO: make the ringbuffer user mmap()able (requires FIXME). |
1016 | */ |
1017 | static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent) |
1018 | { |
1019 | struct aio_ring_info *info = &ioctx->ring_info; |
1020 | struct aio_ring *ring; |
1021 | unsigned long head; |
1022 | int ret = 0; |
1023 | |
1024 | ring = kmap_atomic(info->ring_pages[0], KM_USER0); |
1025 | dprintk("in aio_read_evt h%lu t%lu m%lu\n", |
1026 | (unsigned long)ring->head, (unsigned long)ring->tail, |
1027 | (unsigned long)ring->nr); |
1028 | |
1029 | if (ring->head == ring->tail) |
1030 | goto out; |
1031 | |
1032 | spin_lock(&info->ring_lock); |
1033 | |
1034 | head = ring->head % info->nr; |
1035 | if (head != ring->tail) { |
1036 | struct io_event *evp = aio_ring_event(info, head, KM_USER1); |
1037 | *ent = *evp; |
1038 | head = (head + 1) % info->nr; |
1039 | smp_mb(); /* finish reading the event before updatng the head */ |
1040 | ring->head = head; |
1041 | ret = 1; |
1042 | put_aio_ring_event(evp, KM_USER1); |
1043 | } |
1044 | spin_unlock(&info->ring_lock); |
1045 | |
1046 | out: |
1047 | kunmap_atomic(ring, KM_USER0); |
1048 | dprintk("leaving aio_read_evt: %d h%lu t%lu\n", ret, |
1049 | (unsigned long)ring->head, (unsigned long)ring->tail); |
1050 | return ret; |
1051 | } |
1052 | |
1053 | struct aio_timeout { |
1054 | struct timer_list timer; |
1055 | int timed_out; |
1056 | struct task_struct *p; |
1057 | }; |
1058 | |
1059 | static void timeout_func(unsigned long data) |
1060 | { |
1061 | struct aio_timeout *to = (struct aio_timeout *)data; |
1062 | |
1063 | to->timed_out = 1; |
1064 | wake_up_process(to->p); |
1065 | } |
1066 | |
1067 | static inline void init_timeout(struct aio_timeout *to) |
1068 | { |
1069 | init_timer(&to->timer); |
1070 | to->timer.data = (unsigned long)to; |
1071 | to->timer.function = timeout_func; |
1072 | to->timed_out = 0; |
1073 | to->p = current; |
1074 | } |
1075 | |
1076 | static inline void set_timeout(long start_jiffies, struct aio_timeout *to, |
1077 | const struct timespec *ts) |
1078 | { |
1079 | to->timer.expires = start_jiffies + timespec_to_jiffies(ts); |
1080 | if (time_after(to->timer.expires, jiffies)) |
1081 | add_timer(&to->timer); |
1082 | else |
1083 | to->timed_out = 1; |
1084 | } |
1085 | |
1086 | static inline void clear_timeout(struct aio_timeout *to) |
1087 | { |
1088 | del_singleshot_timer_sync(&to->timer); |
1089 | } |
1090 | |
1091 | static int read_events(struct kioctx *ctx, |
1092 | long min_nr, long nr, |
1093 | struct io_event __user *event, |
1094 | struct timespec __user *timeout) |
1095 | { |
1096 | long start_jiffies = jiffies; |
1097 | struct task_struct *tsk = current; |
1098 | DECLARE_WAITQUEUE(wait, tsk); |
1099 | int ret; |
1100 | int i = 0; |
1101 | struct io_event ent; |
1102 | struct aio_timeout to; |
1103 | int retry = 0; |
1104 | |
1105 | /* needed to zero any padding within an entry (there shouldn't be |
1106 | * any, but C is fun! |
1107 | */ |
1108 | memset(&ent, 0, sizeof(ent)); |
1109 | retry: |
1110 | ret = 0; |
1111 | while (likely(i < nr)) { |
1112 | ret = aio_read_evt(ctx, &ent); |
1113 | if (unlikely(ret <= 0)) |
1114 | break; |
1115 | |
1116 | dprintk("read event: %Lx %Lx %Lx %Lx\n", |
1117 | ent.data, ent.obj, ent.res, ent.res2); |
1118 | |
1119 | /* Could we split the check in two? */ |
1120 | ret = -EFAULT; |
1121 | if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { |
1122 | dprintk("aio: lost an event due to EFAULT.\n"); |
1123 | break; |
1124 | } |
1125 | ret = 0; |
1126 | |
1127 | /* Good, event copied to userland, update counts. */ |
1128 | event ++; |
1129 | i ++; |
1130 | } |
1131 | |
1132 | if (min_nr <= i) |
1133 | return i; |
1134 | if (ret) |
1135 | return ret; |
1136 | |
1137 | /* End fast path */ |
1138 | |
1139 | /* racey check, but it gets redone */ |
1140 | if (!retry && unlikely(!list_empty(&ctx->run_list))) { |
1141 | retry = 1; |
1142 | aio_run_all_iocbs(ctx); |
1143 | goto retry; |
1144 | } |
1145 | |
1146 | init_timeout(&to); |
1147 | if (timeout) { |
1148 | struct timespec ts; |
1149 | ret = -EFAULT; |
1150 | if (unlikely(copy_from_user(&ts, timeout, sizeof(ts)))) |
1151 | goto out; |
1152 | |
1153 | set_timeout(start_jiffies, &to, &ts); |
1154 | } |
1155 | |
1156 | while (likely(i < nr)) { |
1157 | add_wait_queue_exclusive(&ctx->wait, &wait); |
1158 | do { |
1159 | set_task_state(tsk, TASK_INTERRUPTIBLE); |
1160 | ret = aio_read_evt(ctx, &ent); |
1161 | if (ret) |
1162 | break; |
1163 | if (min_nr <= i) |
1164 | break; |
1165 | ret = 0; |
1166 | if (to.timed_out) /* Only check after read evt */ |
1167 | break; |
1168 | schedule(); |
1169 | if (signal_pending(tsk)) { |
1170 | ret = -EINTR; |
1171 | break; |
1172 | } |
1173 | /*ret = aio_read_evt(ctx, &ent);*/ |
1174 | } while (1) ; |
1175 | |
1176 | set_task_state(tsk, TASK_RUNNING); |
1177 | remove_wait_queue(&ctx->wait, &wait); |
1178 | |
1179 | if (unlikely(ret <= 0)) |
1180 | break; |
1181 | |
1182 | ret = -EFAULT; |
1183 | if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { |
1184 | dprintk("aio: lost an event due to EFAULT.\n"); |
1185 | break; |
1186 | } |
1187 | |
1188 | /* Good, event copied to userland, update counts. */ |
1189 | event ++; |
1190 | i ++; |
1191 | } |
1192 | |
1193 | if (timeout) |
1194 | clear_timeout(&to); |
1195 | out: |
1196 | return i ? i : ret; |
1197 | } |
1198 | |
1199 | /* Take an ioctx and remove it from the list of ioctx's. Protects |
1200 | * against races with itself via ->dead. |
1201 | */ |
1202 | static void io_destroy(struct kioctx *ioctx) |
1203 | { |
1204 | struct mm_struct *mm = current->mm; |
1205 | struct kioctx **tmp; |
1206 | int was_dead; |
1207 | |
1208 | /* delete the entry from the list is someone else hasn't already */ |
1209 | write_lock(&mm->ioctx_list_lock); |
1210 | was_dead = ioctx->dead; |
1211 | ioctx->dead = 1; |
1212 | for (tmp = &mm->ioctx_list; *tmp && *tmp != ioctx; |
1213 | tmp = &(*tmp)->next) |
1214 | ; |
1215 | if (*tmp) |
1216 | *tmp = ioctx->next; |
1217 | write_unlock(&mm->ioctx_list_lock); |
1218 | |
1219 | dprintk("aio_release(%p)\n", ioctx); |
1220 | if (likely(!was_dead)) |
1221 | put_ioctx(ioctx); /* twice for the list */ |
1222 | |
1223 | aio_cancel_all(ioctx); |
1224 | wait_for_all_aios(ioctx); |
1225 | put_ioctx(ioctx); /* once for the lookup */ |
1226 | } |
1227 | |
1228 | /* sys_io_setup: |
1229 | * Create an aio_context capable of receiving at least nr_events. |
1230 | * ctxp must not point to an aio_context that already exists, and |
1231 | * must be initialized to 0 prior to the call. On successful |
1232 | * creation of the aio_context, *ctxp is filled in with the resulting |
1233 | * handle. May fail with -EINVAL if *ctxp is not initialized, |
1234 | * if the specified nr_events exceeds internal limits. May fail |
1235 | * with -EAGAIN if the specified nr_events exceeds the user's limit |
1236 | * of available events. May fail with -ENOMEM if insufficient kernel |
1237 | * resources are available. May fail with -EFAULT if an invalid |
1238 | * pointer is passed for ctxp. Will fail with -ENOSYS if not |
1239 | * implemented. |
1240 | */ |
1241 | asmlinkage long sys_io_setup(unsigned nr_events, aio_context_t __user *ctxp) |
1242 | { |
1243 | struct kioctx *ioctx = NULL; |
1244 | unsigned long ctx; |
1245 | long ret; |
1246 | |
1247 | ret = get_user(ctx, ctxp); |
1248 | if (unlikely(ret)) |
1249 | goto out; |
1250 | |
1251 | ret = -EINVAL; |
1252 | if (unlikely(ctx || (int)nr_events <= 0)) { |
1253 | pr_debug("EINVAL: io_setup: ctx or nr_events > max\n"); |
1254 | goto out; |
1255 | } |
1256 | |
1257 | ioctx = ioctx_alloc(nr_events); |
1258 | ret = PTR_ERR(ioctx); |
1259 | if (!IS_ERR(ioctx)) { |
1260 | ret = put_user(ioctx->user_id, ctxp); |
1261 | if (!ret) |
1262 | return 0; |
1263 | |
1264 | get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */ |
1265 | io_destroy(ioctx); |
1266 | } |
1267 | |
1268 | out: |
1269 | return ret; |
1270 | } |
1271 | |
1272 | /* sys_io_destroy: |
1273 | * Destroy the aio_context specified. May cancel any outstanding |
1274 | * AIOs and block on completion. Will fail with -ENOSYS if not |
1275 | * implemented. May fail with -EFAULT if the context pointed to |
1276 | * is invalid. |
1277 | */ |
1278 | asmlinkage long sys_io_destroy(aio_context_t ctx) |
1279 | { |
1280 | struct kioctx *ioctx = lookup_ioctx(ctx); |
1281 | if (likely(NULL != ioctx)) { |
1282 | io_destroy(ioctx); |
1283 | return 0; |
1284 | } |
1285 | pr_debug("EINVAL: io_destroy: invalid context id\n"); |
1286 | return -EINVAL; |
1287 | } |
1288 | |
1289 | /* |
1290 | * Default retry method for aio_read (also used for first time submit) |
1291 | * Responsible for updating iocb state as retries progress |
1292 | */ |
1293 | static ssize_t aio_pread(struct kiocb *iocb) |
1294 | { |
1295 | struct file *file = iocb->ki_filp; |
1296 | struct address_space *mapping = file->f_mapping; |
1297 | struct inode *inode = mapping->host; |
1298 | ssize_t ret = 0; |
1299 | |
1300 | ret = file->f_op->aio_read(iocb, iocb->ki_buf, |
1301 | iocb->ki_left, iocb->ki_pos); |
1302 | |
1303 | /* |
1304 | * Can't just depend on iocb->ki_left to determine |
1305 | * whether we are done. This may have been a short read. |
1306 | */ |
1307 | if (ret > 0) { |
1308 | iocb->ki_buf += ret; |
1309 | iocb->ki_left -= ret; |
1310 | /* |
1311 | * For pipes and sockets we return once we have |
1312 | * some data; for regular files we retry till we |
1313 | * complete the entire read or find that we can't |
1314 | * read any more data (e.g short reads). |
1315 | */ |
1316 | if (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode)) |
1317 | ret = -EIOCBRETRY; |
1318 | } |
1319 | |
1320 | /* This means we must have transferred all that we could */ |
1321 | /* No need to retry anymore */ |
1322 | if ((ret == 0) || (iocb->ki_left == 0)) |
1323 | ret = iocb->ki_nbytes - iocb->ki_left; |
1324 | |
1325 | return ret; |
1326 | } |
1327 | |
1328 | /* |
1329 | * Default retry method for aio_write (also used for first time submit) |
1330 | * Responsible for updating iocb state as retries progress |
1331 | */ |
1332 | static ssize_t aio_pwrite(struct kiocb *iocb) |
1333 | { |
1334 | struct file *file = iocb->ki_filp; |
1335 | ssize_t ret = 0; |
1336 | |
1337 | ret = file->f_op->aio_write(iocb, iocb->ki_buf, |
1338 | iocb->ki_left, iocb->ki_pos); |
1339 | |
1340 | if (ret > 0) { |
1341 | iocb->ki_buf += ret; |
1342 | iocb->ki_left -= ret; |
1343 | |
1344 | ret = -EIOCBRETRY; |
1345 | } |
1346 | |
1347 | /* This means we must have transferred all that we could */ |
1348 | /* No need to retry anymore */ |
1349 | if ((ret == 0) || (iocb->ki_left == 0)) |
1350 | ret = iocb->ki_nbytes - iocb->ki_left; |
1351 | |
1352 | return ret; |
1353 | } |
1354 | |
1355 | static ssize_t aio_fdsync(struct kiocb *iocb) |
1356 | { |
1357 | struct file *file = iocb->ki_filp; |
1358 | ssize_t ret = -EINVAL; |
1359 | |
1360 | if (file->f_op->aio_fsync) |
1361 | ret = file->f_op->aio_fsync(iocb, 1); |
1362 | return ret; |
1363 | } |
1364 | |
1365 | static ssize_t aio_fsync(struct kiocb *iocb) |
1366 | { |
1367 | struct file *file = iocb->ki_filp; |
1368 | ssize_t ret = -EINVAL; |
1369 | |
1370 | if (file->f_op->aio_fsync) |
1371 | ret = file->f_op->aio_fsync(iocb, 0); |
1372 | return ret; |
1373 | } |
1374 | |
1375 | /* |
1376 | * aio_setup_iocb: |
1377 | * Performs the initial checks and aio retry method |
1378 | * setup for the kiocb at the time of io submission. |
1379 | */ |
1380 | static ssize_t aio_setup_iocb(struct kiocb *kiocb) |
1381 | { |
1382 | struct file *file = kiocb->ki_filp; |
1383 | ssize_t ret = 0; |
1384 | |
1385 | switch (kiocb->ki_opcode) { |
1386 | case IOCB_CMD_PREAD: |
1387 | ret = -EBADF; |
1388 | if (unlikely(!(file->f_mode & FMODE_READ))) |
1389 | break; |
1390 | ret = -EFAULT; |
1391 | if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf, |
1392 | kiocb->ki_left))) |
1393 | break; |
1394 | ret = -EINVAL; |
1395 | if (file->f_op->aio_read) |
1396 | kiocb->ki_retry = aio_pread; |
1397 | break; |
1398 | case IOCB_CMD_PWRITE: |
1399 | ret = -EBADF; |
1400 | if (unlikely(!(file->f_mode & FMODE_WRITE))) |
1401 | break; |
1402 | ret = -EFAULT; |
1403 | if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf, |
1404 | kiocb->ki_left))) |
1405 | break; |
1406 | ret = -EINVAL; |
1407 | if (file->f_op->aio_write) |
1408 | kiocb->ki_retry = aio_pwrite; |
1409 | break; |
1410 | case IOCB_CMD_FDSYNC: |
1411 | ret = -EINVAL; |
1412 | if (file->f_op->aio_fsync) |
1413 | kiocb->ki_retry = aio_fdsync; |
1414 | break; |
1415 | case IOCB_CMD_FSYNC: |
1416 | ret = -EINVAL; |
1417 | if (file->f_op->aio_fsync) |
1418 | kiocb->ki_retry = aio_fsync; |
1419 | break; |
1420 | default: |
1421 | dprintk("EINVAL: io_submit: no operation provided\n"); |
1422 | ret = -EINVAL; |
1423 | } |
1424 | |
1425 | if (!kiocb->ki_retry) |
1426 | return ret; |
1427 | |
1428 | return 0; |
1429 | } |
1430 | |
1431 | /* |
1432 | * aio_wake_function: |
1433 | * wait queue callback function for aio notification, |
1434 | * Simply triggers a retry of the operation via kick_iocb. |
1435 | * |
1436 | * This callback is specified in the wait queue entry in |
1437 | * a kiocb (current->io_wait points to this wait queue |
1438 | * entry when an aio operation executes; it is used |
1439 | * instead of a synchronous wait when an i/o blocking |
1440 | * condition is encountered during aio). |
1441 | * |
1442 | * Note: |
1443 | * This routine is executed with the wait queue lock held. |
1444 | * Since kick_iocb acquires iocb->ctx->ctx_lock, it nests |
1445 | * the ioctx lock inside the wait queue lock. This is safe |
1446 | * because this callback isn't used for wait queues which |
1447 | * are nested inside ioctx lock (i.e. ctx->wait) |
1448 | */ |
1449 | static int aio_wake_function(wait_queue_t *wait, unsigned mode, |
1450 | int sync, void *key) |
1451 | { |
1452 | struct kiocb *iocb = container_of(wait, struct kiocb, ki_wait); |
1453 | |
1454 | list_del_init(&wait->task_list); |
1455 | kick_iocb(iocb); |
1456 | return 1; |
1457 | } |
1458 | |
1459 | int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, |
1460 | struct iocb *iocb) |
1461 | { |
1462 | struct kiocb *req; |
1463 | struct file *file; |
1464 | ssize_t ret; |
1465 | |
1466 | /* enforce forwards compatibility on users */ |
1467 | if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2 || |
1468 | iocb->aio_reserved3)) { |
1469 | pr_debug("EINVAL: io_submit: reserve field set\n"); |
1470 | return -EINVAL; |
1471 | } |
1472 | |
1473 | /* prevent overflows */ |
1474 | if (unlikely( |
1475 | (iocb->aio_buf != (unsigned long)iocb->aio_buf) || |
1476 | (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) || |
1477 | ((ssize_t)iocb->aio_nbytes < 0) |
1478 | )) { |
1479 | pr_debug("EINVAL: io_submit: overflow check\n"); |
1480 | return -EINVAL; |
1481 | } |
1482 | |
1483 | file = fget(iocb->aio_fildes); |
1484 | if (unlikely(!file)) |
1485 | return -EBADF; |
1486 | |
1487 | req = aio_get_req(ctx); /* returns with 2 references to req */ |
1488 | if (unlikely(!req)) { |
1489 | fput(file); |
1490 | return -EAGAIN; |
1491 | } |
1492 | |
1493 | req->ki_filp = file; |
1494 | ret = put_user(req->ki_key, &user_iocb->aio_key); |
1495 | if (unlikely(ret)) { |
1496 | dprintk("EFAULT: aio_key\n"); |
1497 | goto out_put_req; |
1498 | } |
1499 | |
1500 | req->ki_obj.user = user_iocb; |
1501 | req->ki_user_data = iocb->aio_data; |
1502 | req->ki_pos = iocb->aio_offset; |
1503 | |
1504 | req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf; |
1505 | req->ki_left = req->ki_nbytes = iocb->aio_nbytes; |
1506 | req->ki_opcode = iocb->aio_lio_opcode; |
1507 | init_waitqueue_func_entry(&req->ki_wait, aio_wake_function); |
1508 | INIT_LIST_HEAD(&req->ki_wait.task_list); |
1509 | req->ki_retried = 0; |
1510 | |
1511 | ret = aio_setup_iocb(req); |
1512 | |
1513 | if (ret) |
1514 | goto out_put_req; |
1515 | |
1516 | spin_lock_irq(&ctx->ctx_lock); |
1517 | if (likely(list_empty(&ctx->run_list))) { |
1518 | aio_run_iocb(req); |
1519 | } else { |
1520 | list_add_tail(&req->ki_run_list, &ctx->run_list); |
1521 | /* drain the run list */ |
1522 | while (__aio_run_iocbs(ctx)) |
1523 | ; |
1524 | } |
1525 | spin_unlock_irq(&ctx->ctx_lock); |
1526 | aio_put_req(req); /* drop extra ref to req */ |
1527 | return 0; |
1528 | |
1529 | out_put_req: |
1530 | aio_put_req(req); /* drop extra ref to req */ |
1531 | aio_put_req(req); /* drop i/o ref to req */ |
1532 | return ret; |
1533 | } |
1534 | |
1535 | /* sys_io_submit: |
1536 | * Queue the nr iocbs pointed to by iocbpp for processing. Returns |
1537 | * the number of iocbs queued. May return -EINVAL if the aio_context |
1538 | * specified by ctx_id is invalid, if nr is < 0, if the iocb at |
1539 | * *iocbpp[0] is not properly initialized, if the operation specified |
1540 | * is invalid for the file descriptor in the iocb. May fail with |
1541 | * -EFAULT if any of the data structures point to invalid data. May |
1542 | * fail with -EBADF if the file descriptor specified in the first |
1543 | * iocb is invalid. May fail with -EAGAIN if insufficient resources |
1544 | * are available to queue any iocbs. Will return 0 if nr is 0. Will |
1545 | * fail with -ENOSYS if not implemented. |
1546 | */ |
1547 | asmlinkage long sys_io_submit(aio_context_t ctx_id, long nr, |
1548 | struct iocb __user * __user *iocbpp) |
1549 | { |
1550 | struct kioctx *ctx; |
1551 | long ret = 0; |
1552 | int i; |
1553 | |
1554 | if (unlikely(nr < 0)) |
1555 | return -EINVAL; |
1556 | |
1557 | if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp))))) |
1558 | return -EFAULT; |
1559 | |
1560 | ctx = lookup_ioctx(ctx_id); |
1561 | if (unlikely(!ctx)) { |
1562 | pr_debug("EINVAL: io_submit: invalid context id\n"); |
1563 | return -EINVAL; |
1564 | } |
1565 | |
1566 | /* |
1567 | * AKPM: should this return a partial result if some of the IOs were |
1568 | * successfully submitted? |
1569 | */ |
1570 | for (i=0; i<nr; i++) { |
1571 | struct iocb __user *user_iocb; |
1572 | struct iocb tmp; |
1573 | |
1574 | if (unlikely(__get_user(user_iocb, iocbpp + i))) { |
1575 | ret = -EFAULT; |
1576 | break; |
1577 | } |
1578 | |
1579 | if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) { |
1580 | ret = -EFAULT; |
1581 | break; |
1582 | } |
1583 | |
1584 | ret = io_submit_one(ctx, user_iocb, &tmp); |
1585 | if (ret) |
1586 | break; |
1587 | } |
1588 | |
1589 | put_ioctx(ctx); |
1590 | return i ? i : ret; |
1591 | } |
1592 | |
1593 | /* lookup_kiocb |
1594 | * Finds a given iocb for cancellation. |
1595 | * MUST be called with ctx->ctx_lock held. |
1596 | */ |
1597 | static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, |
1598 | u32 key) |
1599 | { |
1600 | struct list_head *pos; |
1601 | /* TODO: use a hash or array, this sucks. */ |
1602 | list_for_each(pos, &ctx->active_reqs) { |
1603 | struct kiocb *kiocb = list_kiocb(pos); |
1604 | if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key) |
1605 | return kiocb; |
1606 | } |
1607 | return NULL; |
1608 | } |
1609 | |
1610 | /* sys_io_cancel: |
1611 | * Attempts to cancel an iocb previously passed to io_submit. If |
1612 | * the operation is successfully cancelled, the resulting event is |
1613 | * copied into the memory pointed to by result without being placed |
1614 | * into the completion queue and 0 is returned. May fail with |
1615 | * -EFAULT if any of the data structures pointed to are invalid. |
1616 | * May fail with -EINVAL if aio_context specified by ctx_id is |
1617 | * invalid. May fail with -EAGAIN if the iocb specified was not |
1618 | * cancelled. Will fail with -ENOSYS if not implemented. |
1619 | */ |
1620 | asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb, |
1621 | struct io_event __user *result) |
1622 | { |
1623 | int (*cancel)(struct kiocb *iocb, struct io_event *res); |
1624 | struct kioctx *ctx; |
1625 | struct kiocb *kiocb; |
1626 | u32 key; |
1627 | int ret; |
1628 | |
1629 | ret = get_user(key, &iocb->aio_key); |
1630 | if (unlikely(ret)) |
1631 | return -EFAULT; |
1632 | |
1633 | ctx = lookup_ioctx(ctx_id); |
1634 | if (unlikely(!ctx)) |
1635 | return -EINVAL; |
1636 | |
1637 | spin_lock_irq(&ctx->ctx_lock); |
1638 | ret = -EAGAIN; |
1639 | kiocb = lookup_kiocb(ctx, iocb, key); |
1640 | if (kiocb && kiocb->ki_cancel) { |
1641 | cancel = kiocb->ki_cancel; |
1642 | kiocb->ki_users ++; |
1643 | kiocbSetCancelled(kiocb); |
1644 | } else |
1645 | cancel = NULL; |
1646 | spin_unlock_irq(&ctx->ctx_lock); |
1647 | |
1648 | if (NULL != cancel) { |
1649 | struct io_event tmp; |
1650 | pr_debug("calling cancel\n"); |
1651 | memset(&tmp, 0, sizeof(tmp)); |
1652 | tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user; |
1653 | tmp.data = kiocb->ki_user_data; |
1654 | ret = cancel(kiocb, &tmp); |
1655 | if (!ret) { |
1656 | /* Cancellation succeeded -- copy the result |
1657 | * into the user's buffer. |
1658 | */ |
1659 | if (copy_to_user(result, &tmp, sizeof(tmp))) |
1660 | ret = -EFAULT; |
1661 | } |
1662 | } else |
1663 | printk(KERN_DEBUG "iocb has no cancel operation\n"); |
1664 | |
1665 | put_ioctx(ctx); |
1666 | |
1667 | return ret; |
1668 | } |
1669 | |
1670 | /* io_getevents: |
1671 | * Attempts to read at least min_nr events and up to nr events from |
1672 | * the completion queue for the aio_context specified by ctx_id. May |
1673 | * fail with -EINVAL if ctx_id is invalid, if min_nr is out of range, |
1674 | * if nr is out of range, if when is out of range. May fail with |
1675 | * -EFAULT if any of the memory specified to is invalid. May return |
1676 | * 0 or < min_nr if no events are available and the timeout specified |
1677 | * by when has elapsed, where when == NULL specifies an infinite |
1678 | * timeout. Note that the timeout pointed to by when is relative and |
1679 | * will be updated if not NULL and the operation blocks. Will fail |
1680 | * with -ENOSYS if not implemented. |
1681 | */ |
1682 | asmlinkage long sys_io_getevents(aio_context_t ctx_id, |
1683 | long min_nr, |
1684 | long nr, |
1685 | struct io_event __user *events, |
1686 | struct timespec __user *timeout) |
1687 | { |
1688 | struct kioctx *ioctx = lookup_ioctx(ctx_id); |
1689 | long ret = -EINVAL; |
1690 | |
1691 | if (likely(ioctx)) { |
1692 | if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0)) |
1693 | ret = read_events(ioctx, min_nr, nr, events, timeout); |
1694 | put_ioctx(ioctx); |
1695 | } |
1696 | |
1697 | return ret; |
1698 | } |
1699 | |
1700 | __initcall(aio_setup); |
1701 | |
1702 | EXPORT_SYMBOL(aio_complete); |
1703 | EXPORT_SYMBOL(aio_put_req); |
1704 | EXPORT_SYMBOL(wait_on_sync_kiocb); |