blob: d6b1551342b7206bff66323d60c6a8126bcaf813 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * An async IO implementation for Linux
3 * Written by Benjamin LaHaise <bcrl@kvack.org>
4 *
5 * Implements an efficient asynchronous io interface.
6 *
7 * Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved.
8 *
9 * See ../COPYING for licensing terms.
10 */
11#include <linux/kernel.h>
12#include <linux/init.h>
13#include <linux/errno.h>
14#include <linux/time.h>
15#include <linux/aio_abi.h>
16#include <linux/module.h>
17#include <linux/syscalls.h>
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>
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070032#include <linux/rcuref.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070033
34#include <asm/kmap_types.h>
35#include <asm/uaccess.h>
36#include <asm/mmu_context.h>
37
38#if DEBUG > 1
39#define dprintk printk
40#else
41#define dprintk(x...) do { ; } while (0)
42#endif
43
Linus Torvalds1da177e2005-04-16 15:20:36 -070044/*------ sysctl variables----*/
45atomic_t aio_nr = ATOMIC_INIT(0); /* current system wide number of aio requests */
46unsigned aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
47/*----end sysctl variables---*/
48
49static kmem_cache_t *kiocb_cachep;
50static kmem_cache_t *kioctx_cachep;
51
52static struct workqueue_struct *aio_wq;
53
54/* Used for rare fput completion. */
55static void aio_fput_routine(void *);
56static DECLARE_WORK(fput_work, aio_fput_routine, NULL);
57
58static DEFINE_SPINLOCK(fput_lock);
Adrian Bunk25ee7e32005-04-25 08:18:14 -070059static LIST_HEAD(fput_head);
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
61static void aio_kick_handler(void *);
Sébastien Duguc016e222005-06-28 20:44:59 -070062static void aio_queue_work(struct kioctx *);
Linus Torvalds1da177e2005-04-16 15:20:36 -070063
64/* aio_setup
65 * Creates the slab caches used by the aio routines, panic on
66 * failure as this is done early during the boot sequence.
67 */
68static int __init aio_setup(void)
69{
70 kiocb_cachep = kmem_cache_create("kiocb", sizeof(struct kiocb),
71 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
72 kioctx_cachep = kmem_cache_create("kioctx", sizeof(struct kioctx),
73 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
74
75 aio_wq = create_workqueue("aio");
76
77 pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page));
78
79 return 0;
80}
81
82static void aio_free_ring(struct kioctx *ctx)
83{
84 struct aio_ring_info *info = &ctx->ring_info;
85 long i;
86
87 for (i=0; i<info->nr_pages; i++)
88 put_page(info->ring_pages[i]);
89
90 if (info->mmap_size) {
91 down_write(&ctx->mm->mmap_sem);
92 do_munmap(ctx->mm, info->mmap_base, info->mmap_size);
93 up_write(&ctx->mm->mmap_sem);
94 }
95
96 if (info->ring_pages && info->ring_pages != info->internal_pages)
97 kfree(info->ring_pages);
98 info->ring_pages = NULL;
99 info->nr = 0;
100}
101
102static int aio_setup_ring(struct kioctx *ctx)
103{
104 struct aio_ring *ring;
105 struct aio_ring_info *info = &ctx->ring_info;
106 unsigned nr_events = ctx->max_reqs;
107 unsigned long size;
108 int nr_pages;
109
110 /* Compensate for the ring buffer's head/tail overlap entry */
111 nr_events += 2; /* 1 is required, 2 for good luck */
112
113 size = sizeof(struct aio_ring);
114 size += sizeof(struct io_event) * nr_events;
115 nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT;
116
117 if (nr_pages < 0)
118 return -EINVAL;
119
120 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event);
121
122 info->nr = 0;
123 info->ring_pages = info->internal_pages;
124 if (nr_pages > AIO_RING_PAGES) {
125 info->ring_pages = kmalloc(sizeof(struct page *) * nr_pages, GFP_KERNEL);
126 if (!info->ring_pages)
127 return -ENOMEM;
128 memset(info->ring_pages, 0, sizeof(struct page *) * nr_pages);
129 }
130
131 info->mmap_size = nr_pages * PAGE_SIZE;
132 dprintk("attempting mmap of %lu bytes\n", info->mmap_size);
133 down_write(&ctx->mm->mmap_sem);
134 info->mmap_base = do_mmap(NULL, 0, info->mmap_size,
135 PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE,
136 0);
137 if (IS_ERR((void *)info->mmap_base)) {
138 up_write(&ctx->mm->mmap_sem);
139 printk("mmap err: %ld\n", -info->mmap_base);
140 info->mmap_size = 0;
141 aio_free_ring(ctx);
142 return -EAGAIN;
143 }
144
145 dprintk("mmap address: 0x%08lx\n", info->mmap_base);
146 info->nr_pages = get_user_pages(current, ctx->mm,
147 info->mmap_base, nr_pages,
148 1, 0, info->ring_pages, NULL);
149 up_write(&ctx->mm->mmap_sem);
150
151 if (unlikely(info->nr_pages != nr_pages)) {
152 aio_free_ring(ctx);
153 return -EAGAIN;
154 }
155
156 ctx->user_id = info->mmap_base;
157
158 info->nr = nr_events; /* trusted copy */
159
160 ring = kmap_atomic(info->ring_pages[0], KM_USER0);
161 ring->nr = nr_events; /* user copy */
162 ring->id = ctx->user_id;
163 ring->head = ring->tail = 0;
164 ring->magic = AIO_RING_MAGIC;
165 ring->compat_features = AIO_RING_COMPAT_FEATURES;
166 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
167 ring->header_length = sizeof(struct aio_ring);
168 kunmap_atomic(ring, KM_USER0);
169
170 return 0;
171}
172
173
174/* aio_ring_event: returns a pointer to the event at the given index from
175 * kmap_atomic(, km). Release the pointer with put_aio_ring_event();
176 */
177#define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
178#define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
179#define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
180
181#define aio_ring_event(info, nr, km) ({ \
182 unsigned pos = (nr) + AIO_EVENTS_OFFSET; \
183 struct io_event *__event; \
184 __event = kmap_atomic( \
185 (info)->ring_pages[pos / AIO_EVENTS_PER_PAGE], km); \
186 __event += pos % AIO_EVENTS_PER_PAGE; \
187 __event; \
188})
189
190#define put_aio_ring_event(event, km) do { \
191 struct io_event *__event = (event); \
192 (void)__event; \
193 kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK), km); \
194} while(0)
195
196/* ioctx_alloc
197 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
198 */
199static struct kioctx *ioctx_alloc(unsigned nr_events)
200{
201 struct mm_struct *mm;
202 struct kioctx *ctx;
203
204 /* Prevent overflows */
205 if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
206 (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
207 pr_debug("ENOMEM: nr_events too high\n");
208 return ERR_PTR(-EINVAL);
209 }
210
211 if (nr_events > aio_max_nr)
212 return ERR_PTR(-EAGAIN);
213
214 ctx = kmem_cache_alloc(kioctx_cachep, GFP_KERNEL);
215 if (!ctx)
216 return ERR_PTR(-ENOMEM);
217
218 memset(ctx, 0, sizeof(*ctx));
219 ctx->max_reqs = nr_events;
220 mm = ctx->mm = current->mm;
221 atomic_inc(&mm->mm_count);
222
223 atomic_set(&ctx->users, 1);
224 spin_lock_init(&ctx->ctx_lock);
225 spin_lock_init(&ctx->ring_info.ring_lock);
226 init_waitqueue_head(&ctx->wait);
227
228 INIT_LIST_HEAD(&ctx->active_reqs);
229 INIT_LIST_HEAD(&ctx->run_list);
230 INIT_WORK(&ctx->wq, aio_kick_handler, ctx);
231
232 if (aio_setup_ring(ctx) < 0)
233 goto out_freectx;
234
235 /* limit the number of system wide aios */
236 atomic_add(ctx->max_reqs, &aio_nr); /* undone by __put_ioctx */
237 if (unlikely(atomic_read(&aio_nr) > aio_max_nr))
238 goto out_cleanup;
239
240 /* now link into global list. kludge. FIXME */
241 write_lock(&mm->ioctx_list_lock);
242 ctx->next = mm->ioctx_list;
243 mm->ioctx_list = ctx;
244 write_unlock(&mm->ioctx_list_lock);
245
246 dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
247 ctx, ctx->user_id, current->mm, ctx->ring_info.nr);
248 return ctx;
249
250out_cleanup:
251 atomic_sub(ctx->max_reqs, &aio_nr);
252 ctx->max_reqs = 0; /* prevent __put_ioctx from sub'ing aio_nr */
253 __put_ioctx(ctx);
254 return ERR_PTR(-EAGAIN);
255
256out_freectx:
257 mmdrop(mm);
258 kmem_cache_free(kioctx_cachep, ctx);
259 ctx = ERR_PTR(-ENOMEM);
260
261 dprintk("aio: error allocating ioctx %p\n", ctx);
262 return ctx;
263}
264
265/* aio_cancel_all
266 * Cancels all outstanding aio requests on an aio context. Used
267 * when the processes owning a context have all exited to encourage
268 * the rapid destruction of the kioctx.
269 */
270static void aio_cancel_all(struct kioctx *ctx)
271{
272 int (*cancel)(struct kiocb *, struct io_event *);
273 struct io_event res;
274 spin_lock_irq(&ctx->ctx_lock);
275 ctx->dead = 1;
276 while (!list_empty(&ctx->active_reqs)) {
277 struct list_head *pos = ctx->active_reqs.next;
278 struct kiocb *iocb = list_kiocb(pos);
279 list_del_init(&iocb->ki_list);
280 cancel = iocb->ki_cancel;
281 kiocbSetCancelled(iocb);
282 if (cancel) {
283 iocb->ki_users++;
284 spin_unlock_irq(&ctx->ctx_lock);
285 cancel(iocb, &res);
286 spin_lock_irq(&ctx->ctx_lock);
287 }
288 }
289 spin_unlock_irq(&ctx->ctx_lock);
290}
291
Adrian Bunk25ee7e32005-04-25 08:18:14 -0700292static void wait_for_all_aios(struct kioctx *ctx)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293{
294 struct task_struct *tsk = current;
295 DECLARE_WAITQUEUE(wait, tsk);
296
297 if (!ctx->reqs_active)
298 return;
299
300 add_wait_queue(&ctx->wait, &wait);
301 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
302 while (ctx->reqs_active) {
303 schedule();
304 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
305 }
306 __set_task_state(tsk, TASK_RUNNING);
307 remove_wait_queue(&ctx->wait, &wait);
308}
309
310/* wait_on_sync_kiocb:
311 * Waits on the given sync kiocb to complete.
312 */
313ssize_t fastcall wait_on_sync_kiocb(struct kiocb *iocb)
314{
315 while (iocb->ki_users) {
316 set_current_state(TASK_UNINTERRUPTIBLE);
317 if (!iocb->ki_users)
318 break;
319 schedule();
320 }
321 __set_current_state(TASK_RUNNING);
322 return iocb->ki_user_data;
323}
324
325/* exit_aio: called when the last user of mm goes away. At this point,
326 * there is no way for any new requests to be submited or any of the
327 * io_* syscalls to be called on the context. However, there may be
328 * outstanding requests which hold references to the context; as they
329 * go away, they will call put_ioctx and release any pinned memory
330 * associated with the request (held via struct page * references).
331 */
332void fastcall exit_aio(struct mm_struct *mm)
333{
334 struct kioctx *ctx = mm->ioctx_list;
335 mm->ioctx_list = NULL;
336 while (ctx) {
337 struct kioctx *next = ctx->next;
338 ctx->next = NULL;
339 aio_cancel_all(ctx);
340
341 wait_for_all_aios(ctx);
342 /*
343 * this is an overkill, but ensures we don't leave
344 * the ctx on the aio_wq
345 */
346 flush_workqueue(aio_wq);
347
348 if (1 != atomic_read(&ctx->users))
349 printk(KERN_DEBUG
350 "exit_aio:ioctx still alive: %d %d %d\n",
351 atomic_read(&ctx->users), ctx->dead,
352 ctx->reqs_active);
353 put_ioctx(ctx);
354 ctx = next;
355 }
356}
357
358/* __put_ioctx
359 * Called when the last user of an aio context has gone away,
360 * and the struct needs to be freed.
361 */
362void fastcall __put_ioctx(struct kioctx *ctx)
363{
364 unsigned nr_events = ctx->max_reqs;
365
366 if (unlikely(ctx->reqs_active))
367 BUG();
368
369 cancel_delayed_work(&ctx->wq);
370 flush_workqueue(aio_wq);
371 aio_free_ring(ctx);
372 mmdrop(ctx->mm);
373 ctx->mm = NULL;
374 pr_debug("__put_ioctx: freeing %p\n", ctx);
375 kmem_cache_free(kioctx_cachep, ctx);
376
377 atomic_sub(nr_events, &aio_nr);
378}
379
380/* aio_get_req
381 * Allocate a slot for an aio request. Increments the users count
382 * of the kioctx so that the kioctx stays around until all requests are
383 * complete. Returns NULL if no requests are free.
384 *
385 * Returns with kiocb->users set to 2. The io submit code path holds
386 * an extra reference while submitting the i/o.
387 * This prevents races between the aio code path referencing the
388 * req (after submitting it) and aio_complete() freeing the req.
389 */
390static struct kiocb *FASTCALL(__aio_get_req(struct kioctx *ctx));
391static struct kiocb fastcall *__aio_get_req(struct kioctx *ctx)
392{
393 struct kiocb *req = NULL;
394 struct aio_ring *ring;
395 int okay = 0;
396
397 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
398 if (unlikely(!req))
399 return NULL;
400
401 req->ki_flags = 1 << KIF_LOCKED;
402 req->ki_users = 2;
403 req->ki_key = 0;
404 req->ki_ctx = ctx;
405 req->ki_cancel = NULL;
406 req->ki_retry = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407 req->ki_dtor = NULL;
408 req->private = NULL;
409 INIT_LIST_HEAD(&req->ki_run_list);
410
411 /* Check if the completion queue has enough free space to
412 * accept an event from this io.
413 */
414 spin_lock_irq(&ctx->ctx_lock);
415 ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0);
416 if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) {
417 list_add(&req->ki_list, &ctx->active_reqs);
418 get_ioctx(ctx);
419 ctx->reqs_active++;
420 okay = 1;
421 }
422 kunmap_atomic(ring, KM_USER0);
423 spin_unlock_irq(&ctx->ctx_lock);
424
425 if (!okay) {
426 kmem_cache_free(kiocb_cachep, req);
427 req = NULL;
428 }
429
430 return req;
431}
432
433static inline struct kiocb *aio_get_req(struct kioctx *ctx)
434{
435 struct kiocb *req;
436 /* Handle a potential starvation case -- should be exceedingly rare as
437 * requests will be stuck on fput_head only if the aio_fput_routine is
438 * delayed and the requests were the last user of the struct file.
439 */
440 req = __aio_get_req(ctx);
441 if (unlikely(NULL == req)) {
442 aio_fput_routine(NULL);
443 req = __aio_get_req(ctx);
444 }
445 return req;
446}
447
448static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
449{
450 if (req->ki_dtor)
451 req->ki_dtor(req);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 kmem_cache_free(kiocb_cachep, req);
453 ctx->reqs_active--;
454
455 if (unlikely(!ctx->reqs_active && ctx->dead))
456 wake_up(&ctx->wait);
457}
458
459static void aio_fput_routine(void *data)
460{
461 spin_lock_irq(&fput_lock);
462 while (likely(!list_empty(&fput_head))) {
463 struct kiocb *req = list_kiocb(fput_head.next);
464 struct kioctx *ctx = req->ki_ctx;
465
466 list_del(&req->ki_list);
467 spin_unlock_irq(&fput_lock);
468
469 /* Complete the fput */
470 __fput(req->ki_filp);
471
472 /* Link the iocb into the context's free list */
473 spin_lock_irq(&ctx->ctx_lock);
474 really_put_req(ctx, req);
475 spin_unlock_irq(&ctx->ctx_lock);
476
477 put_ioctx(ctx);
478 spin_lock_irq(&fput_lock);
479 }
480 spin_unlock_irq(&fput_lock);
481}
482
483/* __aio_put_req
484 * Returns true if this put was the last user of the request.
485 */
486static int __aio_put_req(struct kioctx *ctx, struct kiocb *req)
487{
488 dprintk(KERN_DEBUG "aio_put(%p): f_count=%d\n",
489 req, atomic_read(&req->ki_filp->f_count));
490
491 req->ki_users --;
492 if (unlikely(req->ki_users < 0))
493 BUG();
494 if (likely(req->ki_users))
495 return 0;
496 list_del(&req->ki_list); /* remove from active_reqs */
497 req->ki_cancel = NULL;
498 req->ki_retry = NULL;
499
500 /* Must be done under the lock to serialise against cancellation.
501 * Call this aio_fput as it duplicates fput via the fput_work.
502 */
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700503 if (unlikely(rcuref_dec_and_test(&req->ki_filp->f_count))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 get_ioctx(ctx);
505 spin_lock(&fput_lock);
506 list_add(&req->ki_list, &fput_head);
507 spin_unlock(&fput_lock);
508 queue_work(aio_wq, &fput_work);
509 } else
510 really_put_req(ctx, req);
511 return 1;
512}
513
514/* aio_put_req
515 * Returns true if this put was the last user of the kiocb,
516 * false if the request is still in use.
517 */
518int fastcall aio_put_req(struct kiocb *req)
519{
520 struct kioctx *ctx = req->ki_ctx;
521 int ret;
522 spin_lock_irq(&ctx->ctx_lock);
523 ret = __aio_put_req(ctx, req);
524 spin_unlock_irq(&ctx->ctx_lock);
525 if (ret)
526 put_ioctx(ctx);
527 return ret;
528}
529
530/* Lookup an ioctx id. ioctx_list is lockless for reads.
531 * FIXME: this is O(n) and is only suitable for development.
532 */
533struct kioctx *lookup_ioctx(unsigned long ctx_id)
534{
535 struct kioctx *ioctx;
536 struct mm_struct *mm;
537
538 mm = current->mm;
539 read_lock(&mm->ioctx_list_lock);
540 for (ioctx = mm->ioctx_list; ioctx; ioctx = ioctx->next)
541 if (likely(ioctx->user_id == ctx_id && !ioctx->dead)) {
542 get_ioctx(ioctx);
543 break;
544 }
545 read_unlock(&mm->ioctx_list_lock);
546
547 return ioctx;
548}
549
Benjamin LaHaiseac0b1bc2005-09-09 13:02:09 -0700550static int lock_kiocb_action(void *param)
551{
552 schedule();
553 return 0;
554}
555
556static inline void lock_kiocb(struct kiocb *iocb)
557{
558 wait_on_bit_lock(&iocb->ki_flags, KIF_LOCKED, lock_kiocb_action,
559 TASK_UNINTERRUPTIBLE);
560}
561
562static inline void unlock_kiocb(struct kiocb *iocb)
563{
564 kiocbClearLocked(iocb);
Zach Browna464ade2005-09-16 19:28:09 -0700565 smp_mb__after_clear_bit();
Benjamin LaHaiseac0b1bc2005-09-09 13:02:09 -0700566 wake_up_bit(&iocb->ki_flags, KIF_LOCKED);
567}
568
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569/*
570 * use_mm
571 * Makes the calling kernel thread take on the specified
572 * mm context.
573 * Called by the retry thread execute retries within the
574 * iocb issuer's mm context, so that copy_from/to_user
575 * operations work seamlessly for aio.
576 * (Note: this routine is intended to be called only
577 * from a kernel thread context)
578 */
579static void use_mm(struct mm_struct *mm)
580{
581 struct mm_struct *active_mm;
582 struct task_struct *tsk = current;
583
584 task_lock(tsk);
585 tsk->flags |= PF_BORROWED_MM;
586 active_mm = tsk->active_mm;
587 atomic_inc(&mm->mm_count);
588 tsk->mm = mm;
589 tsk->active_mm = mm;
Paolo 'Blaisorblade' Giarrusso1e40cd32005-09-03 15:57:25 -0700590 /*
591 * Note that on UML this *requires* PF_BORROWED_MM to be set, otherwise
592 * it won't work. Update it accordingly if you change it here
593 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 activate_mm(active_mm, mm);
595 task_unlock(tsk);
596
597 mmdrop(active_mm);
598}
599
600/*
601 * unuse_mm
602 * Reverses the effect of use_mm, i.e. releases the
603 * specified mm context which was earlier taken on
604 * by the calling kernel thread
605 * (Note: this routine is intended to be called only
606 * from a kernel thread context)
607 *
608 * Comments: Called with ctx->ctx_lock held. This nests
609 * task_lock instead ctx_lock.
610 */
Adrian Bunk25ee7e32005-04-25 08:18:14 -0700611static void unuse_mm(struct mm_struct *mm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612{
613 struct task_struct *tsk = current;
614
615 task_lock(tsk);
616 tsk->flags &= ~PF_BORROWED_MM;
617 tsk->mm = NULL;
618 /* active_mm is still 'mm' */
619 enter_lazy_tlb(mm, tsk);
620 task_unlock(tsk);
621}
622
623/*
624 * Queue up a kiocb to be retried. Assumes that the kiocb
625 * has already been marked as kicked, and places it on
626 * the retry run list for the corresponding ioctx, if it
627 * isn't already queued. Returns 1 if it actually queued
628 * the kiocb (to tell the caller to activate the work
629 * queue to process it), or 0, if it found that it was
630 * already queued.
631 *
632 * Should be called with the spin lock iocb->ki_ctx->ctx_lock
633 * held
634 */
635static inline int __queue_kicked_iocb(struct kiocb *iocb)
636{
637 struct kioctx *ctx = iocb->ki_ctx;
638
639 if (list_empty(&iocb->ki_run_list)) {
640 list_add_tail(&iocb->ki_run_list,
641 &ctx->run_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642 return 1;
643 }
644 return 0;
645}
646
647/* aio_run_iocb
648 * This is the core aio execution routine. It is
649 * invoked both for initial i/o submission and
650 * subsequent retries via the aio_kick_handler.
651 * Expects to be invoked with iocb->ki_ctx->lock
652 * already held. The lock is released and reaquired
653 * as needed during processing.
654 *
655 * Calls the iocb retry method (already setup for the
656 * iocb on initial submission) for operation specific
657 * handling, but takes care of most of common retry
658 * execution details for a given iocb. The retry method
659 * needs to be non-blocking as far as possible, to avoid
660 * holding up other iocbs waiting to be serviced by the
661 * retry kernel thread.
662 *
663 * The trickier parts in this code have to do with
664 * ensuring that only one retry instance is in progress
665 * for a given iocb at any time. Providing that guarantee
666 * simplifies the coding of individual aio operations as
667 * it avoids various potential races.
668 */
669static ssize_t aio_run_iocb(struct kiocb *iocb)
670{
671 struct kioctx *ctx = iocb->ki_ctx;
672 ssize_t (*retry)(struct kiocb *);
673 ssize_t ret;
674
675 if (iocb->ki_retried++ > 1024*1024) {
676 printk("Maximal retry count. Bytes done %Zd\n",
677 iocb->ki_nbytes - iocb->ki_left);
678 return -EAGAIN;
679 }
680
681 if (!(iocb->ki_retried & 0xff)) {
Ken Chen644d3a02005-05-01 08:59:15 -0700682 pr_debug("%ld retry: %d of %d\n", iocb->ki_retried,
683 iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684 }
685
686 if (!(retry = iocb->ki_retry)) {
687 printk("aio_run_iocb: iocb->ki_retry = NULL\n");
688 return 0;
689 }
690
691 /*
692 * We don't want the next retry iteration for this
693 * operation to start until this one has returned and
694 * updated the iocb state. However, wait_queue functions
695 * can trigger a kick_iocb from interrupt context in the
696 * meantime, indicating that data is available for the next
697 * iteration. We want to remember that and enable the
698 * next retry iteration _after_ we are through with
699 * this one.
700 *
701 * So, in order to be able to register a "kick", but
702 * prevent it from being queued now, we clear the kick
703 * flag, but make the kick code *think* that the iocb is
704 * still on the run list until we are actually done.
705 * When we are done with this iteration, we check if
706 * the iocb was kicked in the meantime and if so, queue
707 * it up afresh.
708 */
709
710 kiocbClearKicked(iocb);
711
712 /*
713 * This is so that aio_complete knows it doesn't need to
714 * pull the iocb off the run list (We can't just call
715 * INIT_LIST_HEAD because we don't want a kick_iocb to
716 * queue this on the run list yet)
717 */
718 iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL;
719 spin_unlock_irq(&ctx->ctx_lock);
720
721 /* Quit retrying if the i/o has been cancelled */
722 if (kiocbIsCancelled(iocb)) {
723 ret = -EINTR;
724 aio_complete(iocb, ret, 0);
725 /* must not access the iocb after this */
726 goto out;
727 }
728
729 /*
730 * Now we are all set to call the retry method in async
731 * context. By setting this thread's io_wait context
732 * to point to the wait queue entry inside the currently
733 * running iocb for the duration of the retry, we ensure
734 * that async notification wakeups are queued by the
735 * operation instead of blocking waits, and when notified,
736 * cause the iocb to be kicked for continuation (through
737 * the aio_wake_function callback).
738 */
739 BUG_ON(current->io_wait != NULL);
740 current->io_wait = &iocb->ki_wait;
741 ret = retry(iocb);
742 current->io_wait = NULL;
743
Zach Brown897f15f2005-09-30 11:58:55 -0700744 if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) {
745 BUG_ON(!list_empty(&iocb->ki_wait.task_list));
746 aio_complete(iocb, ret, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747 }
748out:
749 spin_lock_irq(&ctx->ctx_lock);
750
751 if (-EIOCBRETRY == ret) {
752 /*
753 * OK, now that we are done with this iteration
754 * and know that there is more left to go,
755 * this is where we let go so that a subsequent
756 * "kick" can start the next iteration
757 */
758
759 /* will make __queue_kicked_iocb succeed from here on */
760 INIT_LIST_HEAD(&iocb->ki_run_list);
761 /* we must queue the next iteration ourselves, if it
762 * has already been kicked */
763 if (kiocbIsKicked(iocb)) {
764 __queue_kicked_iocb(iocb);
Sébastien Duguc016e222005-06-28 20:44:59 -0700765
766 /*
767 * __queue_kicked_iocb will always return 1 here, because
768 * iocb->ki_run_list is empty at this point so it should
769 * be safe to unconditionally queue the context into the
770 * work queue.
771 */
772 aio_queue_work(ctx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773 }
774 }
775 return ret;
776}
777
778/*
779 * __aio_run_iocbs:
780 * Process all pending retries queued on the ioctx
781 * run list.
782 * Assumes it is operating within the aio issuer's mm
783 * context. Expects to be called with ctx->ctx_lock held
784 */
785static int __aio_run_iocbs(struct kioctx *ctx)
786{
787 struct kiocb *iocb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 LIST_HEAD(run_list);
789
790 list_splice_init(&ctx->run_list, &run_list);
791 while (!list_empty(&run_list)) {
792 iocb = list_entry(run_list.next, struct kiocb,
793 ki_run_list);
794 list_del(&iocb->ki_run_list);
795 /*
796 * Hold an extra reference while retrying i/o.
797 */
798 iocb->ki_users++; /* grab extra reference */
Benjamin LaHaiseac0b1bc2005-09-09 13:02:09 -0700799 lock_kiocb(iocb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800 aio_run_iocb(iocb);
Benjamin LaHaiseac0b1bc2005-09-09 13:02:09 -0700801 unlock_kiocb(iocb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700802 if (__aio_put_req(ctx, iocb)) /* drop extra ref */
803 put_ioctx(ctx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700805 if (!list_empty(&ctx->run_list))
806 return 1;
807 return 0;
808}
809
810static void aio_queue_work(struct kioctx * ctx)
811{
812 unsigned long timeout;
813 /*
814 * if someone is waiting, get the work started right
815 * away, otherwise, use a longer delay
816 */
817 smp_mb();
818 if (waitqueue_active(&ctx->wait))
819 timeout = 1;
820 else
821 timeout = HZ/10;
822 queue_delayed_work(aio_wq, &ctx->wq, timeout);
823}
824
825
826/*
827 * aio_run_iocbs:
828 * Process all pending retries queued on the ioctx
829 * run list.
830 * Assumes it is operating within the aio issuer's mm
831 * context.
832 */
833static inline void aio_run_iocbs(struct kioctx *ctx)
834{
835 int requeue;
836
837 spin_lock_irq(&ctx->ctx_lock);
838
839 requeue = __aio_run_iocbs(ctx);
840 spin_unlock_irq(&ctx->ctx_lock);
841 if (requeue)
842 aio_queue_work(ctx);
843}
844
845/*
846 * just like aio_run_iocbs, but keeps running them until
847 * the list stays empty
848 */
849static inline void aio_run_all_iocbs(struct kioctx *ctx)
850{
851 spin_lock_irq(&ctx->ctx_lock);
852 while (__aio_run_iocbs(ctx))
853 ;
854 spin_unlock_irq(&ctx->ctx_lock);
855}
856
857/*
858 * aio_kick_handler:
859 * Work queue handler triggered to process pending
860 * retries on an ioctx. Takes on the aio issuer's
861 * mm context before running the iocbs, so that
862 * copy_xxx_user operates on the issuer's address
863 * space.
864 * Run on aiod's context.
865 */
866static void aio_kick_handler(void *data)
867{
868 struct kioctx *ctx = data;
869 mm_segment_t oldfs = get_fs();
870 int requeue;
871
872 set_fs(USER_DS);
873 use_mm(ctx->mm);
874 spin_lock_irq(&ctx->ctx_lock);
875 requeue =__aio_run_iocbs(ctx);
876 unuse_mm(ctx->mm);
877 spin_unlock_irq(&ctx->ctx_lock);
878 set_fs(oldfs);
879 /*
880 * we're in a worker thread already, don't use queue_delayed_work,
881 */
882 if (requeue)
883 queue_work(aio_wq, &ctx->wq);
884}
885
886
887/*
888 * Called by kick_iocb to queue the kiocb for retry
889 * and if required activate the aio work queue to process
890 * it
891 */
Zach Brown998765e2005-09-30 11:58:54 -0700892static void try_queue_kicked_iocb(struct kiocb *iocb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700893{
894 struct kioctx *ctx = iocb->ki_ctx;
895 unsigned long flags;
896 int run = 0;
897
Zach Brown998765e2005-09-30 11:58:54 -0700898 /* We're supposed to be the only path putting the iocb back on the run
899 * list. If we find that the iocb is *back* on a wait queue already
900 * than retry has happened before we could queue the iocb. This also
901 * means that the retry could have completed and freed our iocb, no
902 * good. */
903 BUG_ON((!list_empty(&iocb->ki_wait.task_list)));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904
905 spin_lock_irqsave(&ctx->ctx_lock, flags);
Zach Brown998765e2005-09-30 11:58:54 -0700906 /* set this inside the lock so that we can't race with aio_run_iocb()
907 * testing it and putting the iocb on the run list under the lock */
908 if (!kiocbTryKick(iocb))
909 run = __queue_kicked_iocb(iocb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700910 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
Ken Chen644d3a02005-05-01 08:59:15 -0700911 if (run)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700912 aio_queue_work(ctx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913}
914
915/*
916 * kick_iocb:
917 * Called typically from a wait queue callback context
918 * (aio_wake_function) to trigger a retry of the iocb.
919 * The retry is usually executed by aio workqueue
920 * threads (See aio_kick_handler).
921 */
922void fastcall kick_iocb(struct kiocb *iocb)
923{
924 /* sync iocbs are easy: they can only ever be executing from a
925 * single context. */
926 if (is_sync_kiocb(iocb)) {
927 kiocbSetKicked(iocb);
928 wake_up_process(iocb->ki_obj.tsk);
929 return;
930 }
931
Zach Brown998765e2005-09-30 11:58:54 -0700932 try_queue_kicked_iocb(iocb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700933}
934EXPORT_SYMBOL(kick_iocb);
935
936/* aio_complete
937 * Called when the io request on the given iocb is complete.
938 * Returns true if this is the last user of the request. The
939 * only other user of the request can be the cancellation code.
940 */
941int fastcall aio_complete(struct kiocb *iocb, long res, long res2)
942{
943 struct kioctx *ctx = iocb->ki_ctx;
944 struct aio_ring_info *info;
945 struct aio_ring *ring;
946 struct io_event *event;
947 unsigned long flags;
948 unsigned long tail;
949 int ret;
950
951 /* Special case handling for sync iocbs: events go directly
952 * into the iocb for fast handling. Note that this will not
953 * work if we allow sync kiocbs to be cancelled. in which
954 * case the usage count checks will have to move under ctx_lock
955 * for all cases.
956 */
957 if (is_sync_kiocb(iocb)) {
958 int ret;
959
960 iocb->ki_user_data = res;
961 if (iocb->ki_users == 1) {
962 iocb->ki_users = 0;
963 ret = 1;
964 } else {
965 spin_lock_irq(&ctx->ctx_lock);
966 iocb->ki_users--;
967 ret = (0 == iocb->ki_users);
968 spin_unlock_irq(&ctx->ctx_lock);
969 }
970 /* sync iocbs put the task here for us */
971 wake_up_process(iocb->ki_obj.tsk);
972 return ret;
973 }
974
975 info = &ctx->ring_info;
976
977 /* add a completion event to the ring buffer.
978 * must be done holding ctx->ctx_lock to prevent
979 * other code from messing with the tail
980 * pointer since we might be called from irq
981 * context.
982 */
983 spin_lock_irqsave(&ctx->ctx_lock, flags);
984
985 if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list))
986 list_del_init(&iocb->ki_run_list);
987
988 /*
989 * cancelled requests don't get events, userland was given one
990 * when the event got cancelled.
991 */
992 if (kiocbIsCancelled(iocb))
993 goto put_rq;
994
995 ring = kmap_atomic(info->ring_pages[0], KM_IRQ1);
996
997 tail = info->tail;
998 event = aio_ring_event(info, tail, KM_IRQ0);
Ken Chen4bf69b22005-05-01 08:59:15 -0700999 if (++tail >= info->nr)
1000 tail = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001001
1002 event->obj = (u64)(unsigned long)iocb->ki_obj.user;
1003 event->data = iocb->ki_user_data;
1004 event->res = res;
1005 event->res2 = res2;
1006
1007 dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n",
1008 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
1009 res, res2);
1010
1011 /* after flagging the request as done, we
1012 * must never even look at it again
1013 */
1014 smp_wmb(); /* make event visible before updating tail */
1015
1016 info->tail = tail;
1017 ring->tail = tail;
1018
1019 put_aio_ring_event(event, KM_IRQ0);
1020 kunmap_atomic(ring, KM_IRQ1);
1021
1022 pr_debug("added to ring %p at [%lu]\n", iocb, tail);
1023
Ken Chen644d3a02005-05-01 08:59:15 -07001024 pr_debug("%ld retries: %d of %d\n", iocb->ki_retried,
1025 iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001026put_rq:
1027 /* everything turned out well, dispose of the aiocb. */
1028 ret = __aio_put_req(ctx, iocb);
1029
1030 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1031
1032 if (waitqueue_active(&ctx->wait))
1033 wake_up(&ctx->wait);
1034
1035 if (ret)
1036 put_ioctx(ctx);
1037
1038 return ret;
1039}
1040
1041/* aio_read_evt
1042 * Pull an event off of the ioctx's event ring. Returns the number of
1043 * events fetched (0 or 1 ;-)
1044 * FIXME: make this use cmpxchg.
1045 * TODO: make the ringbuffer user mmap()able (requires FIXME).
1046 */
1047static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent)
1048{
1049 struct aio_ring_info *info = &ioctx->ring_info;
1050 struct aio_ring *ring;
1051 unsigned long head;
1052 int ret = 0;
1053
1054 ring = kmap_atomic(info->ring_pages[0], KM_USER0);
1055 dprintk("in aio_read_evt h%lu t%lu m%lu\n",
1056 (unsigned long)ring->head, (unsigned long)ring->tail,
1057 (unsigned long)ring->nr);
1058
1059 if (ring->head == ring->tail)
1060 goto out;
1061
1062 spin_lock(&info->ring_lock);
1063
1064 head = ring->head % info->nr;
1065 if (head != ring->tail) {
1066 struct io_event *evp = aio_ring_event(info, head, KM_USER1);
1067 *ent = *evp;
1068 head = (head + 1) % info->nr;
1069 smp_mb(); /* finish reading the event before updatng the head */
1070 ring->head = head;
1071 ret = 1;
1072 put_aio_ring_event(evp, KM_USER1);
1073 }
1074 spin_unlock(&info->ring_lock);
1075
1076out:
1077 kunmap_atomic(ring, KM_USER0);
1078 dprintk("leaving aio_read_evt: %d h%lu t%lu\n", ret,
1079 (unsigned long)ring->head, (unsigned long)ring->tail);
1080 return ret;
1081}
1082
1083struct aio_timeout {
1084 struct timer_list timer;
1085 int timed_out;
1086 struct task_struct *p;
1087};
1088
1089static void timeout_func(unsigned long data)
1090{
1091 struct aio_timeout *to = (struct aio_timeout *)data;
1092
1093 to->timed_out = 1;
1094 wake_up_process(to->p);
1095}
1096
1097static inline void init_timeout(struct aio_timeout *to)
1098{
1099 init_timer(&to->timer);
1100 to->timer.data = (unsigned long)to;
1101 to->timer.function = timeout_func;
1102 to->timed_out = 0;
1103 to->p = current;
1104}
1105
1106static inline void set_timeout(long start_jiffies, struct aio_timeout *to,
1107 const struct timespec *ts)
1108{
1109 to->timer.expires = start_jiffies + timespec_to_jiffies(ts);
1110 if (time_after(to->timer.expires, jiffies))
1111 add_timer(&to->timer);
1112 else
1113 to->timed_out = 1;
1114}
1115
1116static inline void clear_timeout(struct aio_timeout *to)
1117{
1118 del_singleshot_timer_sync(&to->timer);
1119}
1120
1121static int read_events(struct kioctx *ctx,
1122 long min_nr, long nr,
1123 struct io_event __user *event,
1124 struct timespec __user *timeout)
1125{
1126 long start_jiffies = jiffies;
1127 struct task_struct *tsk = current;
1128 DECLARE_WAITQUEUE(wait, tsk);
1129 int ret;
1130 int i = 0;
1131 struct io_event ent;
1132 struct aio_timeout to;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001133 int retry = 0;
1134
1135 /* needed to zero any padding within an entry (there shouldn't be
1136 * any, but C is fun!
1137 */
1138 memset(&ent, 0, sizeof(ent));
1139retry:
1140 ret = 0;
1141 while (likely(i < nr)) {
1142 ret = aio_read_evt(ctx, &ent);
1143 if (unlikely(ret <= 0))
1144 break;
1145
1146 dprintk("read event: %Lx %Lx %Lx %Lx\n",
1147 ent.data, ent.obj, ent.res, ent.res2);
1148
1149 /* Could we split the check in two? */
1150 ret = -EFAULT;
1151 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
1152 dprintk("aio: lost an event due to EFAULT.\n");
1153 break;
1154 }
1155 ret = 0;
1156
1157 /* Good, event copied to userland, update counts. */
1158 event ++;
1159 i ++;
1160 }
1161
1162 if (min_nr <= i)
1163 return i;
1164 if (ret)
1165 return ret;
1166
1167 /* End fast path */
1168
1169 /* racey check, but it gets redone */
1170 if (!retry && unlikely(!list_empty(&ctx->run_list))) {
1171 retry = 1;
1172 aio_run_all_iocbs(ctx);
1173 goto retry;
1174 }
1175
1176 init_timeout(&to);
1177 if (timeout) {
1178 struct timespec ts;
1179 ret = -EFAULT;
1180 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
1181 goto out;
1182
1183 set_timeout(start_jiffies, &to, &ts);
1184 }
1185
1186 while (likely(i < nr)) {
1187 add_wait_queue_exclusive(&ctx->wait, &wait);
1188 do {
1189 set_task_state(tsk, TASK_INTERRUPTIBLE);
1190 ret = aio_read_evt(ctx, &ent);
1191 if (ret)
1192 break;
1193 if (min_nr <= i)
1194 break;
1195 ret = 0;
1196 if (to.timed_out) /* Only check after read evt */
1197 break;
1198 schedule();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001199 if (signal_pending(tsk)) {
1200 ret = -EINTR;
1201 break;
1202 }
1203 /*ret = aio_read_evt(ctx, &ent);*/
1204 } while (1) ;
1205
1206 set_task_state(tsk, TASK_RUNNING);
1207 remove_wait_queue(&ctx->wait, &wait);
1208
1209 if (unlikely(ret <= 0))
1210 break;
1211
1212 ret = -EFAULT;
1213 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
1214 dprintk("aio: lost an event due to EFAULT.\n");
1215 break;
1216 }
1217
1218 /* Good, event copied to userland, update counts. */
1219 event ++;
1220 i ++;
1221 }
1222
1223 if (timeout)
1224 clear_timeout(&to);
1225out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001226 return i ? i : ret;
1227}
1228
1229/* Take an ioctx and remove it from the list of ioctx's. Protects
1230 * against races with itself via ->dead.
1231 */
1232static void io_destroy(struct kioctx *ioctx)
1233{
1234 struct mm_struct *mm = current->mm;
1235 struct kioctx **tmp;
1236 int was_dead;
1237
1238 /* delete the entry from the list is someone else hasn't already */
1239 write_lock(&mm->ioctx_list_lock);
1240 was_dead = ioctx->dead;
1241 ioctx->dead = 1;
1242 for (tmp = &mm->ioctx_list; *tmp && *tmp != ioctx;
1243 tmp = &(*tmp)->next)
1244 ;
1245 if (*tmp)
1246 *tmp = ioctx->next;
1247 write_unlock(&mm->ioctx_list_lock);
1248
1249 dprintk("aio_release(%p)\n", ioctx);
1250 if (likely(!was_dead))
1251 put_ioctx(ioctx); /* twice for the list */
1252
1253 aio_cancel_all(ioctx);
1254 wait_for_all_aios(ioctx);
1255 put_ioctx(ioctx); /* once for the lookup */
1256}
1257
1258/* sys_io_setup:
1259 * Create an aio_context capable of receiving at least nr_events.
1260 * ctxp must not point to an aio_context that already exists, and
1261 * must be initialized to 0 prior to the call. On successful
1262 * creation of the aio_context, *ctxp is filled in with the resulting
1263 * handle. May fail with -EINVAL if *ctxp is not initialized,
1264 * if the specified nr_events exceeds internal limits. May fail
1265 * with -EAGAIN if the specified nr_events exceeds the user's limit
1266 * of available events. May fail with -ENOMEM if insufficient kernel
1267 * resources are available. May fail with -EFAULT if an invalid
1268 * pointer is passed for ctxp. Will fail with -ENOSYS if not
1269 * implemented.
1270 */
1271asmlinkage long sys_io_setup(unsigned nr_events, aio_context_t __user *ctxp)
1272{
1273 struct kioctx *ioctx = NULL;
1274 unsigned long ctx;
1275 long ret;
1276
1277 ret = get_user(ctx, ctxp);
1278 if (unlikely(ret))
1279 goto out;
1280
1281 ret = -EINVAL;
1282 if (unlikely(ctx || (int)nr_events <= 0)) {
1283 pr_debug("EINVAL: io_setup: ctx or nr_events > max\n");
1284 goto out;
1285 }
1286
1287 ioctx = ioctx_alloc(nr_events);
1288 ret = PTR_ERR(ioctx);
1289 if (!IS_ERR(ioctx)) {
1290 ret = put_user(ioctx->user_id, ctxp);
1291 if (!ret)
1292 return 0;
1293
1294 get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */
1295 io_destroy(ioctx);
1296 }
1297
1298out:
1299 return ret;
1300}
1301
1302/* sys_io_destroy:
1303 * Destroy the aio_context specified. May cancel any outstanding
1304 * AIOs and block on completion. Will fail with -ENOSYS if not
1305 * implemented. May fail with -EFAULT if the context pointed to
1306 * is invalid.
1307 */
1308asmlinkage long sys_io_destroy(aio_context_t ctx)
1309{
1310 struct kioctx *ioctx = lookup_ioctx(ctx);
1311 if (likely(NULL != ioctx)) {
1312 io_destroy(ioctx);
1313 return 0;
1314 }
1315 pr_debug("EINVAL: io_destroy: invalid context id\n");
1316 return -EINVAL;
1317}
1318
1319/*
Zach Brown897f15f2005-09-30 11:58:55 -07001320 * aio_p{read,write} are the default ki_retry methods for
1321 * IO_CMD_P{READ,WRITE}. They maintains kiocb retry state around potentially
1322 * multiple calls to f_op->aio_read(). They loop around partial progress
1323 * instead of returning -EIOCBRETRY because they don't have the means to call
1324 * kick_iocb().
Linus Torvalds1da177e2005-04-16 15:20:36 -07001325 */
1326static ssize_t aio_pread(struct kiocb *iocb)
1327{
1328 struct file *file = iocb->ki_filp;
1329 struct address_space *mapping = file->f_mapping;
1330 struct inode *inode = mapping->host;
1331 ssize_t ret = 0;
1332
Zach Brown897f15f2005-09-30 11:58:55 -07001333 do {
1334 ret = file->f_op->aio_read(iocb, iocb->ki_buf,
1335 iocb->ki_left, iocb->ki_pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001336 /*
Zach Brown897f15f2005-09-30 11:58:55 -07001337 * Can't just depend on iocb->ki_left to determine
1338 * whether we are done. This may have been a short read.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001339 */
Zach Brown897f15f2005-09-30 11:58:55 -07001340 if (ret > 0) {
1341 iocb->ki_buf += ret;
1342 iocb->ki_left -= ret;
1343 }
1344
1345 /*
1346 * For pipes and sockets we return once we have some data; for
1347 * regular files we retry till we complete the entire read or
1348 * find that we can't read any more data (e.g short reads).
1349 */
Zach Brown353fb072005-09-30 11:58:56 -07001350 } while (ret > 0 && iocb->ki_left > 0 &&
Zach Brown897f15f2005-09-30 11:58:55 -07001351 !S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001352
1353 /* This means we must have transferred all that we could */
1354 /* No need to retry anymore */
1355 if ((ret == 0) || (iocb->ki_left == 0))
1356 ret = iocb->ki_nbytes - iocb->ki_left;
1357
1358 return ret;
1359}
1360
Zach Brown897f15f2005-09-30 11:58:55 -07001361/* see aio_pread() */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001362static ssize_t aio_pwrite(struct kiocb *iocb)
1363{
1364 struct file *file = iocb->ki_filp;
1365 ssize_t ret = 0;
1366
Zach Brown897f15f2005-09-30 11:58:55 -07001367 do {
1368 ret = file->f_op->aio_write(iocb, iocb->ki_buf,
1369 iocb->ki_left, iocb->ki_pos);
1370 if (ret > 0) {
1371 iocb->ki_buf += ret;
1372 iocb->ki_left -= ret;
1373 }
Zach Brown353fb072005-09-30 11:58:56 -07001374 } while (ret > 0 && iocb->ki_left > 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001375
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376 if ((ret == 0) || (iocb->ki_left == 0))
1377 ret = iocb->ki_nbytes - iocb->ki_left;
1378
1379 return ret;
1380}
1381
1382static ssize_t aio_fdsync(struct kiocb *iocb)
1383{
1384 struct file *file = iocb->ki_filp;
1385 ssize_t ret = -EINVAL;
1386
1387 if (file->f_op->aio_fsync)
1388 ret = file->f_op->aio_fsync(iocb, 1);
1389 return ret;
1390}
1391
1392static ssize_t aio_fsync(struct kiocb *iocb)
1393{
1394 struct file *file = iocb->ki_filp;
1395 ssize_t ret = -EINVAL;
1396
1397 if (file->f_op->aio_fsync)
1398 ret = file->f_op->aio_fsync(iocb, 0);
1399 return ret;
1400}
1401
1402/*
1403 * aio_setup_iocb:
1404 * Performs the initial checks and aio retry method
1405 * setup for the kiocb at the time of io submission.
1406 */
Adrian Bunk25ee7e32005-04-25 08:18:14 -07001407static ssize_t aio_setup_iocb(struct kiocb *kiocb)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001408{
1409 struct file *file = kiocb->ki_filp;
1410 ssize_t ret = 0;
1411
1412 switch (kiocb->ki_opcode) {
1413 case IOCB_CMD_PREAD:
1414 ret = -EBADF;
1415 if (unlikely(!(file->f_mode & FMODE_READ)))
1416 break;
1417 ret = -EFAULT;
1418 if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf,
1419 kiocb->ki_left)))
1420 break;
1421 ret = -EINVAL;
1422 if (file->f_op->aio_read)
1423 kiocb->ki_retry = aio_pread;
1424 break;
1425 case IOCB_CMD_PWRITE:
1426 ret = -EBADF;
1427 if (unlikely(!(file->f_mode & FMODE_WRITE)))
1428 break;
1429 ret = -EFAULT;
1430 if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf,
1431 kiocb->ki_left)))
1432 break;
1433 ret = -EINVAL;
1434 if (file->f_op->aio_write)
1435 kiocb->ki_retry = aio_pwrite;
1436 break;
1437 case IOCB_CMD_FDSYNC:
1438 ret = -EINVAL;
1439 if (file->f_op->aio_fsync)
1440 kiocb->ki_retry = aio_fdsync;
1441 break;
1442 case IOCB_CMD_FSYNC:
1443 ret = -EINVAL;
1444 if (file->f_op->aio_fsync)
1445 kiocb->ki_retry = aio_fsync;
1446 break;
1447 default:
1448 dprintk("EINVAL: io_submit: no operation provided\n");
1449 ret = -EINVAL;
1450 }
1451
1452 if (!kiocb->ki_retry)
1453 return ret;
1454
1455 return 0;
1456}
1457
1458/*
1459 * aio_wake_function:
1460 * wait queue callback function for aio notification,
1461 * Simply triggers a retry of the operation via kick_iocb.
1462 *
1463 * This callback is specified in the wait queue entry in
1464 * a kiocb (current->io_wait points to this wait queue
1465 * entry when an aio operation executes; it is used
1466 * instead of a synchronous wait when an i/o blocking
1467 * condition is encountered during aio).
1468 *
1469 * Note:
1470 * This routine is executed with the wait queue lock held.
1471 * Since kick_iocb acquires iocb->ctx->ctx_lock, it nests
1472 * the ioctx lock inside the wait queue lock. This is safe
1473 * because this callback isn't used for wait queues which
1474 * are nested inside ioctx lock (i.e. ctx->wait)
1475 */
Adrian Bunk25ee7e32005-04-25 08:18:14 -07001476static int aio_wake_function(wait_queue_t *wait, unsigned mode,
1477 int sync, void *key)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001478{
1479 struct kiocb *iocb = container_of(wait, struct kiocb, ki_wait);
1480
1481 list_del_init(&wait->task_list);
1482 kick_iocb(iocb);
1483 return 1;
1484}
1485
1486int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1487 struct iocb *iocb)
1488{
1489 struct kiocb *req;
1490 struct file *file;
1491 ssize_t ret;
1492
1493 /* enforce forwards compatibility on users */
1494 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2 ||
1495 iocb->aio_reserved3)) {
1496 pr_debug("EINVAL: io_submit: reserve field set\n");
1497 return -EINVAL;
1498 }
1499
1500 /* prevent overflows */
1501 if (unlikely(
1502 (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
1503 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
1504 ((ssize_t)iocb->aio_nbytes < 0)
1505 )) {
1506 pr_debug("EINVAL: io_submit: overflow check\n");
1507 return -EINVAL;
1508 }
1509
1510 file = fget(iocb->aio_fildes);
1511 if (unlikely(!file))
1512 return -EBADF;
1513
1514 req = aio_get_req(ctx); /* returns with 2 references to req */
1515 if (unlikely(!req)) {
1516 fput(file);
1517 return -EAGAIN;
1518 }
1519
1520 req->ki_filp = file;
Ken Chen212079c2005-05-01 08:59:15 -07001521 ret = put_user(req->ki_key, &user_iocb->aio_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001522 if (unlikely(ret)) {
1523 dprintk("EFAULT: aio_key\n");
1524 goto out_put_req;
1525 }
1526
1527 req->ki_obj.user = user_iocb;
1528 req->ki_user_data = iocb->aio_data;
1529 req->ki_pos = iocb->aio_offset;
1530
1531 req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf;
1532 req->ki_left = req->ki_nbytes = iocb->aio_nbytes;
1533 req->ki_opcode = iocb->aio_lio_opcode;
1534 init_waitqueue_func_entry(&req->ki_wait, aio_wake_function);
1535 INIT_LIST_HEAD(&req->ki_wait.task_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536 req->ki_retried = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001537
1538 ret = aio_setup_iocb(req);
1539
1540 if (ret)
1541 goto out_put_req;
1542
1543 spin_lock_irq(&ctx->ctx_lock);
Benjamin LaHaiseac0b1bc2005-09-09 13:02:09 -07001544 aio_run_iocb(req);
1545 unlock_kiocb(req);
1546 if (!list_empty(&ctx->run_list)) {
Ken Chen954d3e92005-05-01 08:59:16 -07001547 /* drain the run list */
1548 while (__aio_run_iocbs(ctx))
1549 ;
1550 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001551 spin_unlock_irq(&ctx->ctx_lock);
1552 aio_put_req(req); /* drop extra ref to req */
1553 return 0;
1554
1555out_put_req:
1556 aio_put_req(req); /* drop extra ref to req */
1557 aio_put_req(req); /* drop i/o ref to req */
1558 return ret;
1559}
1560
1561/* sys_io_submit:
1562 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1563 * the number of iocbs queued. May return -EINVAL if the aio_context
1564 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1565 * *iocbpp[0] is not properly initialized, if the operation specified
1566 * is invalid for the file descriptor in the iocb. May fail with
1567 * -EFAULT if any of the data structures point to invalid data. May
1568 * fail with -EBADF if the file descriptor specified in the first
1569 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1570 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1571 * fail with -ENOSYS if not implemented.
1572 */
1573asmlinkage long sys_io_submit(aio_context_t ctx_id, long nr,
1574 struct iocb __user * __user *iocbpp)
1575{
1576 struct kioctx *ctx;
1577 long ret = 0;
1578 int i;
1579
1580 if (unlikely(nr < 0))
1581 return -EINVAL;
1582
1583 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1584 return -EFAULT;
1585
1586 ctx = lookup_ioctx(ctx_id);
1587 if (unlikely(!ctx)) {
1588 pr_debug("EINVAL: io_submit: invalid context id\n");
1589 return -EINVAL;
1590 }
1591
1592 /*
1593 * AKPM: should this return a partial result if some of the IOs were
1594 * successfully submitted?
1595 */
1596 for (i=0; i<nr; i++) {
1597 struct iocb __user *user_iocb;
1598 struct iocb tmp;
1599
1600 if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1601 ret = -EFAULT;
1602 break;
1603 }
1604
1605 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1606 ret = -EFAULT;
1607 break;
1608 }
1609
1610 ret = io_submit_one(ctx, user_iocb, &tmp);
1611 if (ret)
1612 break;
1613 }
1614
1615 put_ioctx(ctx);
1616 return i ? i : ret;
1617}
1618
1619/* lookup_kiocb
1620 * Finds a given iocb for cancellation.
1621 * MUST be called with ctx->ctx_lock held.
1622 */
Adrian Bunk25ee7e32005-04-25 08:18:14 -07001623static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
1624 u32 key)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001625{
1626 struct list_head *pos;
1627 /* TODO: use a hash or array, this sucks. */
1628 list_for_each(pos, &ctx->active_reqs) {
1629 struct kiocb *kiocb = list_kiocb(pos);
1630 if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key)
1631 return kiocb;
1632 }
1633 return NULL;
1634}
1635
1636/* sys_io_cancel:
1637 * Attempts to cancel an iocb previously passed to io_submit. If
1638 * the operation is successfully cancelled, the resulting event is
1639 * copied into the memory pointed to by result without being placed
1640 * into the completion queue and 0 is returned. May fail with
1641 * -EFAULT if any of the data structures pointed to are invalid.
1642 * May fail with -EINVAL if aio_context specified by ctx_id is
1643 * invalid. May fail with -EAGAIN if the iocb specified was not
1644 * cancelled. Will fail with -ENOSYS if not implemented.
1645 */
1646asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb,
1647 struct io_event __user *result)
1648{
1649 int (*cancel)(struct kiocb *iocb, struct io_event *res);
1650 struct kioctx *ctx;
1651 struct kiocb *kiocb;
1652 u32 key;
1653 int ret;
1654
1655 ret = get_user(key, &iocb->aio_key);
1656 if (unlikely(ret))
1657 return -EFAULT;
1658
1659 ctx = lookup_ioctx(ctx_id);
1660 if (unlikely(!ctx))
1661 return -EINVAL;
1662
1663 spin_lock_irq(&ctx->ctx_lock);
1664 ret = -EAGAIN;
1665 kiocb = lookup_kiocb(ctx, iocb, key);
1666 if (kiocb && kiocb->ki_cancel) {
1667 cancel = kiocb->ki_cancel;
1668 kiocb->ki_users ++;
1669 kiocbSetCancelled(kiocb);
1670 } else
1671 cancel = NULL;
1672 spin_unlock_irq(&ctx->ctx_lock);
1673
1674 if (NULL != cancel) {
1675 struct io_event tmp;
1676 pr_debug("calling cancel\n");
Benjamin LaHaiseac0b1bc2005-09-09 13:02:09 -07001677 lock_kiocb(kiocb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001678 memset(&tmp, 0, sizeof(tmp));
1679 tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user;
1680 tmp.data = kiocb->ki_user_data;
1681 ret = cancel(kiocb, &tmp);
1682 if (!ret) {
1683 /* Cancellation succeeded -- copy the result
1684 * into the user's buffer.
1685 */
1686 if (copy_to_user(result, &tmp, sizeof(tmp)))
1687 ret = -EFAULT;
1688 }
Benjamin LaHaiseac0b1bc2005-09-09 13:02:09 -07001689 unlock_kiocb(kiocb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001690 } else
Wendy Cheng8f582022005-09-09 13:02:08 -07001691 ret = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692
1693 put_ioctx(ctx);
1694
1695 return ret;
1696}
1697
1698/* io_getevents:
1699 * Attempts to read at least min_nr events and up to nr events from
1700 * the completion queue for the aio_context specified by ctx_id. May
1701 * fail with -EINVAL if ctx_id is invalid, if min_nr is out of range,
1702 * if nr is out of range, if when is out of range. May fail with
1703 * -EFAULT if any of the memory specified to is invalid. May return
1704 * 0 or < min_nr if no events are available and the timeout specified
1705 * by when has elapsed, where when == NULL specifies an infinite
1706 * timeout. Note that the timeout pointed to by when is relative and
1707 * will be updated if not NULL and the operation blocks. Will fail
1708 * with -ENOSYS if not implemented.
1709 */
1710asmlinkage long sys_io_getevents(aio_context_t ctx_id,
1711 long min_nr,
1712 long nr,
1713 struct io_event __user *events,
1714 struct timespec __user *timeout)
1715{
1716 struct kioctx *ioctx = lookup_ioctx(ctx_id);
1717 long ret = -EINVAL;
1718
1719 if (likely(ioctx)) {
1720 if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0))
1721 ret = read_events(ioctx, min_nr, nr, events, timeout);
1722 put_ioctx(ioctx);
1723 }
1724
1725 return ret;
1726}
1727
1728__initcall(aio_setup);
1729
1730EXPORT_SYMBOL(aio_complete);
1731EXPORT_SYMBOL(aio_put_req);
1732EXPORT_SYMBOL(wait_on_sync_kiocb);