blob: e7cd40b626b7f3bd06446e7d01da5c7aaab623de [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----*/
Zach Brownd55b5fd2005-11-07 00:59:31 -080045static DEFINE_SPINLOCK(aio_nr_lock);
46unsigned long aio_nr; /* current system wide number of aio requests */
47unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
Linus Torvalds1da177e2005-04-16 15:20:36 -070048/*----end sysctl variables---*/
49
50static kmem_cache_t *kiocb_cachep;
51static kmem_cache_t *kioctx_cachep;
52
53static struct workqueue_struct *aio_wq;
54
55/* Used for rare fput completion. */
56static void aio_fput_routine(void *);
57static DECLARE_WORK(fput_work, aio_fput_routine, NULL);
58
59static DEFINE_SPINLOCK(fput_lock);
Adrian Bunk25ee7e32005-04-25 08:18:14 -070060static LIST_HEAD(fput_head);
Linus Torvalds1da177e2005-04-16 15:20:36 -070061
62static void aio_kick_handler(void *);
Sébastien Duguc016e222005-06-28 20:44:59 -070063static void aio_queue_work(struct kioctx *);
Linus Torvalds1da177e2005-04-16 15:20:36 -070064
65/* aio_setup
66 * Creates the slab caches used by the aio routines, panic on
67 * failure as this is done early during the boot sequence.
68 */
69static int __init aio_setup(void)
70{
71 kiocb_cachep = kmem_cache_create("kiocb", sizeof(struct kiocb),
72 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
73 kioctx_cachep = kmem_cache_create("kioctx", sizeof(struct kioctx),
74 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
75
76 aio_wq = create_workqueue("aio");
77
78 pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page));
79
80 return 0;
81}
82
83static void aio_free_ring(struct kioctx *ctx)
84{
85 struct aio_ring_info *info = &ctx->ring_info;
86 long i;
87
88 for (i=0; i<info->nr_pages; i++)
89 put_page(info->ring_pages[i]);
90
91 if (info->mmap_size) {
92 down_write(&ctx->mm->mmap_sem);
93 do_munmap(ctx->mm, info->mmap_base, info->mmap_size);
94 up_write(&ctx->mm->mmap_sem);
95 }
96
97 if (info->ring_pages && info->ring_pages != info->internal_pages)
98 kfree(info->ring_pages);
99 info->ring_pages = NULL;
100 info->nr = 0;
101}
102
103static int aio_setup_ring(struct kioctx *ctx)
104{
105 struct aio_ring *ring;
106 struct aio_ring_info *info = &ctx->ring_info;
107 unsigned nr_events = ctx->max_reqs;
108 unsigned long size;
109 int nr_pages;
110
111 /* Compensate for the ring buffer's head/tail overlap entry */
112 nr_events += 2; /* 1 is required, 2 for good luck */
113
114 size = sizeof(struct aio_ring);
115 size += sizeof(struct io_event) * nr_events;
116 nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT;
117
118 if (nr_pages < 0)
119 return -EINVAL;
120
121 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event);
122
123 info->nr = 0;
124 info->ring_pages = info->internal_pages;
125 if (nr_pages > AIO_RING_PAGES) {
126 info->ring_pages = kmalloc(sizeof(struct page *) * nr_pages, GFP_KERNEL);
127 if (!info->ring_pages)
128 return -ENOMEM;
129 memset(info->ring_pages, 0, sizeof(struct page *) * nr_pages);
130 }
131
132 info->mmap_size = nr_pages * PAGE_SIZE;
133 dprintk("attempting mmap of %lu bytes\n", info->mmap_size);
134 down_write(&ctx->mm->mmap_sem);
135 info->mmap_base = do_mmap(NULL, 0, info->mmap_size,
136 PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE,
137 0);
138 if (IS_ERR((void *)info->mmap_base)) {
139 up_write(&ctx->mm->mmap_sem);
140 printk("mmap err: %ld\n", -info->mmap_base);
141 info->mmap_size = 0;
142 aio_free_ring(ctx);
143 return -EAGAIN;
144 }
145
146 dprintk("mmap address: 0x%08lx\n", info->mmap_base);
147 info->nr_pages = get_user_pages(current, ctx->mm,
148 info->mmap_base, nr_pages,
149 1, 0, info->ring_pages, NULL);
150 up_write(&ctx->mm->mmap_sem);
151
152 if (unlikely(info->nr_pages != nr_pages)) {
153 aio_free_ring(ctx);
154 return -EAGAIN;
155 }
156
157 ctx->user_id = info->mmap_base;
158
159 info->nr = nr_events; /* trusted copy */
160
161 ring = kmap_atomic(info->ring_pages[0], KM_USER0);
162 ring->nr = nr_events; /* user copy */
163 ring->id = ctx->user_id;
164 ring->head = ring->tail = 0;
165 ring->magic = AIO_RING_MAGIC;
166 ring->compat_features = AIO_RING_COMPAT_FEATURES;
167 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
168 ring->header_length = sizeof(struct aio_ring);
169 kunmap_atomic(ring, KM_USER0);
170
171 return 0;
172}
173
174
175/* aio_ring_event: returns a pointer to the event at the given index from
176 * kmap_atomic(, km). Release the pointer with put_aio_ring_event();
177 */
178#define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
179#define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
180#define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
181
182#define aio_ring_event(info, nr, km) ({ \
183 unsigned pos = (nr) + AIO_EVENTS_OFFSET; \
184 struct io_event *__event; \
185 __event = kmap_atomic( \
186 (info)->ring_pages[pos / AIO_EVENTS_PER_PAGE], km); \
187 __event += pos % AIO_EVENTS_PER_PAGE; \
188 __event; \
189})
190
191#define put_aio_ring_event(event, km) do { \
192 struct io_event *__event = (event); \
193 (void)__event; \
194 kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK), km); \
195} while(0)
196
197/* ioctx_alloc
198 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
199 */
200static struct kioctx *ioctx_alloc(unsigned nr_events)
201{
202 struct mm_struct *mm;
203 struct kioctx *ctx;
204
205 /* Prevent overflows */
206 if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
207 (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
208 pr_debug("ENOMEM: nr_events too high\n");
209 return ERR_PTR(-EINVAL);
210 }
211
Zach Brownd55b5fd2005-11-07 00:59:31 -0800212 if ((unsigned long)nr_events > aio_max_nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 return ERR_PTR(-EAGAIN);
214
215 ctx = kmem_cache_alloc(kioctx_cachep, GFP_KERNEL);
216 if (!ctx)
217 return ERR_PTR(-ENOMEM);
218
219 memset(ctx, 0, sizeof(*ctx));
220 ctx->max_reqs = nr_events;
221 mm = ctx->mm = current->mm;
222 atomic_inc(&mm->mm_count);
223
224 atomic_set(&ctx->users, 1);
225 spin_lock_init(&ctx->ctx_lock);
226 spin_lock_init(&ctx->ring_info.ring_lock);
227 init_waitqueue_head(&ctx->wait);
228
229 INIT_LIST_HEAD(&ctx->active_reqs);
230 INIT_LIST_HEAD(&ctx->run_list);
231 INIT_WORK(&ctx->wq, aio_kick_handler, ctx);
232
233 if (aio_setup_ring(ctx) < 0)
234 goto out_freectx;
235
236 /* limit the number of system wide aios */
Zach Brownd55b5fd2005-11-07 00:59:31 -0800237 spin_lock(&aio_nr_lock);
238 if (aio_nr + ctx->max_reqs > aio_max_nr ||
239 aio_nr + ctx->max_reqs < aio_nr)
240 ctx->max_reqs = 0;
241 else
242 aio_nr += ctx->max_reqs;
243 spin_unlock(&aio_nr_lock);
244 if (ctx->max_reqs == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 goto out_cleanup;
246
247 /* now link into global list. kludge. FIXME */
248 write_lock(&mm->ioctx_list_lock);
249 ctx->next = mm->ioctx_list;
250 mm->ioctx_list = ctx;
251 write_unlock(&mm->ioctx_list_lock);
252
253 dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
254 ctx, ctx->user_id, current->mm, ctx->ring_info.nr);
255 return ctx;
256
257out_cleanup:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 __put_ioctx(ctx);
259 return ERR_PTR(-EAGAIN);
260
261out_freectx:
262 mmdrop(mm);
263 kmem_cache_free(kioctx_cachep, ctx);
264 ctx = ERR_PTR(-ENOMEM);
265
266 dprintk("aio: error allocating ioctx %p\n", ctx);
267 return ctx;
268}
269
270/* aio_cancel_all
271 * Cancels all outstanding aio requests on an aio context. Used
272 * when the processes owning a context have all exited to encourage
273 * the rapid destruction of the kioctx.
274 */
275static void aio_cancel_all(struct kioctx *ctx)
276{
277 int (*cancel)(struct kiocb *, struct io_event *);
278 struct io_event res;
279 spin_lock_irq(&ctx->ctx_lock);
280 ctx->dead = 1;
281 while (!list_empty(&ctx->active_reqs)) {
282 struct list_head *pos = ctx->active_reqs.next;
283 struct kiocb *iocb = list_kiocb(pos);
284 list_del_init(&iocb->ki_list);
285 cancel = iocb->ki_cancel;
286 kiocbSetCancelled(iocb);
287 if (cancel) {
288 iocb->ki_users++;
289 spin_unlock_irq(&ctx->ctx_lock);
290 cancel(iocb, &res);
291 spin_lock_irq(&ctx->ctx_lock);
292 }
293 }
294 spin_unlock_irq(&ctx->ctx_lock);
295}
296
Adrian Bunk25ee7e32005-04-25 08:18:14 -0700297static void wait_for_all_aios(struct kioctx *ctx)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298{
299 struct task_struct *tsk = current;
300 DECLARE_WAITQUEUE(wait, tsk);
301
302 if (!ctx->reqs_active)
303 return;
304
305 add_wait_queue(&ctx->wait, &wait);
306 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
307 while (ctx->reqs_active) {
308 schedule();
309 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
310 }
311 __set_task_state(tsk, TASK_RUNNING);
312 remove_wait_queue(&ctx->wait, &wait);
313}
314
315/* wait_on_sync_kiocb:
316 * Waits on the given sync kiocb to complete.
317 */
318ssize_t fastcall wait_on_sync_kiocb(struct kiocb *iocb)
319{
320 while (iocb->ki_users) {
321 set_current_state(TASK_UNINTERRUPTIBLE);
322 if (!iocb->ki_users)
323 break;
324 schedule();
325 }
326 __set_current_state(TASK_RUNNING);
327 return iocb->ki_user_data;
328}
329
330/* exit_aio: called when the last user of mm goes away. At this point,
331 * there is no way for any new requests to be submited or any of the
332 * io_* syscalls to be called on the context. However, there may be
333 * outstanding requests which hold references to the context; as they
334 * go away, they will call put_ioctx and release any pinned memory
335 * associated with the request (held via struct page * references).
336 */
337void fastcall exit_aio(struct mm_struct *mm)
338{
339 struct kioctx *ctx = mm->ioctx_list;
340 mm->ioctx_list = NULL;
341 while (ctx) {
342 struct kioctx *next = ctx->next;
343 ctx->next = NULL;
344 aio_cancel_all(ctx);
345
346 wait_for_all_aios(ctx);
347 /*
348 * this is an overkill, but ensures we don't leave
349 * the ctx on the aio_wq
350 */
351 flush_workqueue(aio_wq);
352
353 if (1 != atomic_read(&ctx->users))
354 printk(KERN_DEBUG
355 "exit_aio:ioctx still alive: %d %d %d\n",
356 atomic_read(&ctx->users), ctx->dead,
357 ctx->reqs_active);
358 put_ioctx(ctx);
359 ctx = next;
360 }
361}
362
363/* __put_ioctx
364 * Called when the last user of an aio context has gone away,
365 * and the struct needs to be freed.
366 */
367void fastcall __put_ioctx(struct kioctx *ctx)
368{
369 unsigned nr_events = ctx->max_reqs;
370
371 if (unlikely(ctx->reqs_active))
372 BUG();
373
374 cancel_delayed_work(&ctx->wq);
375 flush_workqueue(aio_wq);
376 aio_free_ring(ctx);
377 mmdrop(ctx->mm);
378 ctx->mm = NULL;
379 pr_debug("__put_ioctx: freeing %p\n", ctx);
380 kmem_cache_free(kioctx_cachep, ctx);
381
Zach Brownd55b5fd2005-11-07 00:59:31 -0800382 if (nr_events) {
383 spin_lock(&aio_nr_lock);
384 BUG_ON(aio_nr - nr_events > aio_nr);
385 aio_nr -= nr_events;
386 spin_unlock(&aio_nr_lock);
387 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388}
389
390/* aio_get_req
391 * Allocate a slot for an aio request. Increments the users count
392 * of the kioctx so that the kioctx stays around until all requests are
393 * complete. Returns NULL if no requests are free.
394 *
395 * Returns with kiocb->users set to 2. The io submit code path holds
396 * an extra reference while submitting the i/o.
397 * This prevents races between the aio code path referencing the
398 * req (after submitting it) and aio_complete() freeing the req.
399 */
400static struct kiocb *FASTCALL(__aio_get_req(struct kioctx *ctx));
401static struct kiocb fastcall *__aio_get_req(struct kioctx *ctx)
402{
403 struct kiocb *req = NULL;
404 struct aio_ring *ring;
405 int okay = 0;
406
407 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
408 if (unlikely(!req))
409 return NULL;
410
Zach Brown4faa5282005-10-17 16:43:33 -0700411 req->ki_flags = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 req->ki_users = 2;
413 req->ki_key = 0;
414 req->ki_ctx = ctx;
415 req->ki_cancel = NULL;
416 req->ki_retry = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 req->ki_dtor = NULL;
418 req->private = NULL;
419 INIT_LIST_HEAD(&req->ki_run_list);
420
421 /* Check if the completion queue has enough free space to
422 * accept an event from this io.
423 */
424 spin_lock_irq(&ctx->ctx_lock);
425 ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0);
426 if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) {
427 list_add(&req->ki_list, &ctx->active_reqs);
428 get_ioctx(ctx);
429 ctx->reqs_active++;
430 okay = 1;
431 }
432 kunmap_atomic(ring, KM_USER0);
433 spin_unlock_irq(&ctx->ctx_lock);
434
435 if (!okay) {
436 kmem_cache_free(kiocb_cachep, req);
437 req = NULL;
438 }
439
440 return req;
441}
442
443static inline struct kiocb *aio_get_req(struct kioctx *ctx)
444{
445 struct kiocb *req;
446 /* Handle a potential starvation case -- should be exceedingly rare as
447 * requests will be stuck on fput_head only if the aio_fput_routine is
448 * delayed and the requests were the last user of the struct file.
449 */
450 req = __aio_get_req(ctx);
451 if (unlikely(NULL == req)) {
452 aio_fput_routine(NULL);
453 req = __aio_get_req(ctx);
454 }
455 return req;
456}
457
458static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
459{
460 if (req->ki_dtor)
461 req->ki_dtor(req);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462 kmem_cache_free(kiocb_cachep, req);
463 ctx->reqs_active--;
464
465 if (unlikely(!ctx->reqs_active && ctx->dead))
466 wake_up(&ctx->wait);
467}
468
469static void aio_fput_routine(void *data)
470{
471 spin_lock_irq(&fput_lock);
472 while (likely(!list_empty(&fput_head))) {
473 struct kiocb *req = list_kiocb(fput_head.next);
474 struct kioctx *ctx = req->ki_ctx;
475
476 list_del(&req->ki_list);
477 spin_unlock_irq(&fput_lock);
478
479 /* Complete the fput */
480 __fput(req->ki_filp);
481
482 /* Link the iocb into the context's free list */
483 spin_lock_irq(&ctx->ctx_lock);
484 really_put_req(ctx, req);
485 spin_unlock_irq(&ctx->ctx_lock);
486
487 put_ioctx(ctx);
488 spin_lock_irq(&fput_lock);
489 }
490 spin_unlock_irq(&fput_lock);
491}
492
493/* __aio_put_req
494 * Returns true if this put was the last user of the request.
495 */
496static int __aio_put_req(struct kioctx *ctx, struct kiocb *req)
497{
498 dprintk(KERN_DEBUG "aio_put(%p): f_count=%d\n",
499 req, atomic_read(&req->ki_filp->f_count));
500
501 req->ki_users --;
502 if (unlikely(req->ki_users < 0))
503 BUG();
504 if (likely(req->ki_users))
505 return 0;
506 list_del(&req->ki_list); /* remove from active_reqs */
507 req->ki_cancel = NULL;
508 req->ki_retry = NULL;
509
510 /* Must be done under the lock to serialise against cancellation.
511 * Call this aio_fput as it duplicates fput via the fput_work.
512 */
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700513 if (unlikely(rcuref_dec_and_test(&req->ki_filp->f_count))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514 get_ioctx(ctx);
515 spin_lock(&fput_lock);
516 list_add(&req->ki_list, &fput_head);
517 spin_unlock(&fput_lock);
518 queue_work(aio_wq, &fput_work);
519 } else
520 really_put_req(ctx, req);
521 return 1;
522}
523
524/* aio_put_req
525 * Returns true if this put was the last user of the kiocb,
526 * false if the request is still in use.
527 */
528int fastcall aio_put_req(struct kiocb *req)
529{
530 struct kioctx *ctx = req->ki_ctx;
531 int ret;
532 spin_lock_irq(&ctx->ctx_lock);
533 ret = __aio_put_req(ctx, req);
534 spin_unlock_irq(&ctx->ctx_lock);
535 if (ret)
536 put_ioctx(ctx);
537 return ret;
538}
539
540/* Lookup an ioctx id. ioctx_list is lockless for reads.
541 * FIXME: this is O(n) and is only suitable for development.
542 */
543struct kioctx *lookup_ioctx(unsigned long ctx_id)
544{
545 struct kioctx *ioctx;
546 struct mm_struct *mm;
547
548 mm = current->mm;
549 read_lock(&mm->ioctx_list_lock);
550 for (ioctx = mm->ioctx_list; ioctx; ioctx = ioctx->next)
551 if (likely(ioctx->user_id == ctx_id && !ioctx->dead)) {
552 get_ioctx(ioctx);
553 break;
554 }
555 read_unlock(&mm->ioctx_list_lock);
556
557 return ioctx;
558}
559
560/*
561 * use_mm
562 * Makes the calling kernel thread take on the specified
563 * mm context.
564 * Called by the retry thread execute retries within the
565 * iocb issuer's mm context, so that copy_from/to_user
566 * operations work seamlessly for aio.
567 * (Note: this routine is intended to be called only
568 * from a kernel thread context)
569 */
570static void use_mm(struct mm_struct *mm)
571{
572 struct mm_struct *active_mm;
573 struct task_struct *tsk = current;
574
575 task_lock(tsk);
576 tsk->flags |= PF_BORROWED_MM;
577 active_mm = tsk->active_mm;
578 atomic_inc(&mm->mm_count);
579 tsk->mm = mm;
580 tsk->active_mm = mm;
Paolo 'Blaisorblade' Giarrusso1e40cd32005-09-03 15:57:25 -0700581 /*
582 * Note that on UML this *requires* PF_BORROWED_MM to be set, otherwise
583 * it won't work. Update it accordingly if you change it here
584 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585 activate_mm(active_mm, mm);
586 task_unlock(tsk);
587
588 mmdrop(active_mm);
589}
590
591/*
592 * unuse_mm
593 * Reverses the effect of use_mm, i.e. releases the
594 * specified mm context which was earlier taken on
595 * by the calling kernel thread
596 * (Note: this routine is intended to be called only
597 * from a kernel thread context)
598 *
599 * Comments: Called with ctx->ctx_lock held. This nests
600 * task_lock instead ctx_lock.
601 */
Adrian Bunk25ee7e32005-04-25 08:18:14 -0700602static void unuse_mm(struct mm_struct *mm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603{
604 struct task_struct *tsk = current;
605
606 task_lock(tsk);
607 tsk->flags &= ~PF_BORROWED_MM;
608 tsk->mm = NULL;
609 /* active_mm is still 'mm' */
610 enter_lazy_tlb(mm, tsk);
611 task_unlock(tsk);
612}
613
614/*
615 * Queue up a kiocb to be retried. Assumes that the kiocb
616 * has already been marked as kicked, and places it on
617 * the retry run list for the corresponding ioctx, if it
618 * isn't already queued. Returns 1 if it actually queued
619 * the kiocb (to tell the caller to activate the work
620 * queue to process it), or 0, if it found that it was
621 * already queued.
622 *
623 * Should be called with the spin lock iocb->ki_ctx->ctx_lock
624 * held
625 */
626static inline int __queue_kicked_iocb(struct kiocb *iocb)
627{
628 struct kioctx *ctx = iocb->ki_ctx;
629
630 if (list_empty(&iocb->ki_run_list)) {
631 list_add_tail(&iocb->ki_run_list,
632 &ctx->run_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 return 1;
634 }
635 return 0;
636}
637
638/* aio_run_iocb
639 * This is the core aio execution routine. It is
640 * invoked both for initial i/o submission and
641 * subsequent retries via the aio_kick_handler.
642 * Expects to be invoked with iocb->ki_ctx->lock
643 * already held. The lock is released and reaquired
644 * as needed during processing.
645 *
646 * Calls the iocb retry method (already setup for the
647 * iocb on initial submission) for operation specific
648 * handling, but takes care of most of common retry
649 * execution details for a given iocb. The retry method
650 * needs to be non-blocking as far as possible, to avoid
651 * holding up other iocbs waiting to be serviced by the
652 * retry kernel thread.
653 *
654 * The trickier parts in this code have to do with
655 * ensuring that only one retry instance is in progress
656 * for a given iocb at any time. Providing that guarantee
657 * simplifies the coding of individual aio operations as
658 * it avoids various potential races.
659 */
660static ssize_t aio_run_iocb(struct kiocb *iocb)
661{
662 struct kioctx *ctx = iocb->ki_ctx;
663 ssize_t (*retry)(struct kiocb *);
664 ssize_t ret;
665
666 if (iocb->ki_retried++ > 1024*1024) {
667 printk("Maximal retry count. Bytes done %Zd\n",
668 iocb->ki_nbytes - iocb->ki_left);
669 return -EAGAIN;
670 }
671
672 if (!(iocb->ki_retried & 0xff)) {
Ken Chen644d3a02005-05-01 08:59:15 -0700673 pr_debug("%ld retry: %d of %d\n", iocb->ki_retried,
674 iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675 }
676
677 if (!(retry = iocb->ki_retry)) {
678 printk("aio_run_iocb: iocb->ki_retry = NULL\n");
679 return 0;
680 }
681
682 /*
683 * We don't want the next retry iteration for this
684 * operation to start until this one has returned and
685 * updated the iocb state. However, wait_queue functions
686 * can trigger a kick_iocb from interrupt context in the
687 * meantime, indicating that data is available for the next
688 * iteration. We want to remember that and enable the
689 * next retry iteration _after_ we are through with
690 * this one.
691 *
692 * So, in order to be able to register a "kick", but
693 * prevent it from being queued now, we clear the kick
694 * flag, but make the kick code *think* that the iocb is
695 * still on the run list until we are actually done.
696 * When we are done with this iteration, we check if
697 * the iocb was kicked in the meantime and if so, queue
698 * it up afresh.
699 */
700
701 kiocbClearKicked(iocb);
702
703 /*
704 * This is so that aio_complete knows it doesn't need to
705 * pull the iocb off the run list (We can't just call
706 * INIT_LIST_HEAD because we don't want a kick_iocb to
707 * queue this on the run list yet)
708 */
709 iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL;
710 spin_unlock_irq(&ctx->ctx_lock);
711
712 /* Quit retrying if the i/o has been cancelled */
713 if (kiocbIsCancelled(iocb)) {
714 ret = -EINTR;
715 aio_complete(iocb, ret, 0);
716 /* must not access the iocb after this */
717 goto out;
718 }
719
720 /*
721 * Now we are all set to call the retry method in async
722 * context. By setting this thread's io_wait context
723 * to point to the wait queue entry inside the currently
724 * running iocb for the duration of the retry, we ensure
725 * that async notification wakeups are queued by the
726 * operation instead of blocking waits, and when notified,
727 * cause the iocb to be kicked for continuation (through
728 * the aio_wake_function callback).
729 */
730 BUG_ON(current->io_wait != NULL);
731 current->io_wait = &iocb->ki_wait;
732 ret = retry(iocb);
733 current->io_wait = NULL;
734
Zach Brown897f15f2005-09-30 11:58:55 -0700735 if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) {
736 BUG_ON(!list_empty(&iocb->ki_wait.task_list));
737 aio_complete(iocb, ret, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738 }
739out:
740 spin_lock_irq(&ctx->ctx_lock);
741
742 if (-EIOCBRETRY == ret) {
743 /*
744 * OK, now that we are done with this iteration
745 * and know that there is more left to go,
746 * this is where we let go so that a subsequent
747 * "kick" can start the next iteration
748 */
749
750 /* will make __queue_kicked_iocb succeed from here on */
751 INIT_LIST_HEAD(&iocb->ki_run_list);
752 /* we must queue the next iteration ourselves, if it
753 * has already been kicked */
754 if (kiocbIsKicked(iocb)) {
755 __queue_kicked_iocb(iocb);
Sébastien Duguc016e222005-06-28 20:44:59 -0700756
757 /*
758 * __queue_kicked_iocb will always return 1 here, because
759 * iocb->ki_run_list is empty at this point so it should
760 * be safe to unconditionally queue the context into the
761 * work queue.
762 */
763 aio_queue_work(ctx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 }
765 }
766 return ret;
767}
768
769/*
770 * __aio_run_iocbs:
771 * Process all pending retries queued on the ioctx
772 * run list.
773 * Assumes it is operating within the aio issuer's mm
774 * context. Expects to be called with ctx->ctx_lock held
775 */
776static int __aio_run_iocbs(struct kioctx *ctx)
777{
778 struct kiocb *iocb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779 LIST_HEAD(run_list);
780
781 list_splice_init(&ctx->run_list, &run_list);
782 while (!list_empty(&run_list)) {
783 iocb = list_entry(run_list.next, struct kiocb,
784 ki_run_list);
785 list_del(&iocb->ki_run_list);
786 /*
787 * Hold an extra reference while retrying i/o.
788 */
789 iocb->ki_users++; /* grab extra reference */
790 aio_run_iocb(iocb);
791 if (__aio_put_req(ctx, iocb)) /* drop extra ref */
792 put_ioctx(ctx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794 if (!list_empty(&ctx->run_list))
795 return 1;
796 return 0;
797}
798
799static void aio_queue_work(struct kioctx * ctx)
800{
801 unsigned long timeout;
802 /*
803 * if someone is waiting, get the work started right
804 * away, otherwise, use a longer delay
805 */
806 smp_mb();
807 if (waitqueue_active(&ctx->wait))
808 timeout = 1;
809 else
810 timeout = HZ/10;
811 queue_delayed_work(aio_wq, &ctx->wq, timeout);
812}
813
814
815/*
816 * aio_run_iocbs:
817 * Process all pending retries queued on the ioctx
818 * run list.
819 * Assumes it is operating within the aio issuer's mm
820 * context.
821 */
822static inline void aio_run_iocbs(struct kioctx *ctx)
823{
824 int requeue;
825
826 spin_lock_irq(&ctx->ctx_lock);
827
828 requeue = __aio_run_iocbs(ctx);
829 spin_unlock_irq(&ctx->ctx_lock);
830 if (requeue)
831 aio_queue_work(ctx);
832}
833
834/*
835 * just like aio_run_iocbs, but keeps running them until
836 * the list stays empty
837 */
838static inline void aio_run_all_iocbs(struct kioctx *ctx)
839{
840 spin_lock_irq(&ctx->ctx_lock);
841 while (__aio_run_iocbs(ctx))
842 ;
843 spin_unlock_irq(&ctx->ctx_lock);
844}
845
846/*
847 * aio_kick_handler:
848 * Work queue handler triggered to process pending
849 * retries on an ioctx. Takes on the aio issuer's
850 * mm context before running the iocbs, so that
851 * copy_xxx_user operates on the issuer's address
852 * space.
853 * Run on aiod's context.
854 */
855static void aio_kick_handler(void *data)
856{
857 struct kioctx *ctx = data;
858 mm_segment_t oldfs = get_fs();
859 int requeue;
860
861 set_fs(USER_DS);
862 use_mm(ctx->mm);
863 spin_lock_irq(&ctx->ctx_lock);
864 requeue =__aio_run_iocbs(ctx);
865 unuse_mm(ctx->mm);
866 spin_unlock_irq(&ctx->ctx_lock);
867 set_fs(oldfs);
868 /*
869 * we're in a worker thread already, don't use queue_delayed_work,
870 */
871 if (requeue)
872 queue_work(aio_wq, &ctx->wq);
873}
874
875
876/*
877 * Called by kick_iocb to queue the kiocb for retry
878 * and if required activate the aio work queue to process
879 * it
880 */
Zach Brown998765e2005-09-30 11:58:54 -0700881static void try_queue_kicked_iocb(struct kiocb *iocb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882{
883 struct kioctx *ctx = iocb->ki_ctx;
884 unsigned long flags;
885 int run = 0;
886
Zach Brown998765e2005-09-30 11:58:54 -0700887 /* We're supposed to be the only path putting the iocb back on the run
888 * list. If we find that the iocb is *back* on a wait queue already
889 * than retry has happened before we could queue the iocb. This also
890 * means that the retry could have completed and freed our iocb, no
891 * good. */
892 BUG_ON((!list_empty(&iocb->ki_wait.task_list)));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700893
894 spin_lock_irqsave(&ctx->ctx_lock, flags);
Zach Brown998765e2005-09-30 11:58:54 -0700895 /* set this inside the lock so that we can't race with aio_run_iocb()
896 * testing it and putting the iocb on the run list under the lock */
897 if (!kiocbTryKick(iocb))
898 run = __queue_kicked_iocb(iocb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700899 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
Ken Chen644d3a02005-05-01 08:59:15 -0700900 if (run)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 aio_queue_work(ctx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700902}
903
904/*
905 * kick_iocb:
906 * Called typically from a wait queue callback context
907 * (aio_wake_function) to trigger a retry of the iocb.
908 * The retry is usually executed by aio workqueue
909 * threads (See aio_kick_handler).
910 */
911void fastcall kick_iocb(struct kiocb *iocb)
912{
913 /* sync iocbs are easy: they can only ever be executing from a
914 * single context. */
915 if (is_sync_kiocb(iocb)) {
916 kiocbSetKicked(iocb);
917 wake_up_process(iocb->ki_obj.tsk);
918 return;
919 }
920
Zach Brown998765e2005-09-30 11:58:54 -0700921 try_queue_kicked_iocb(iocb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922}
923EXPORT_SYMBOL(kick_iocb);
924
925/* aio_complete
926 * Called when the io request on the given iocb is complete.
927 * Returns true if this is the last user of the request. The
928 * only other user of the request can be the cancellation code.
929 */
930int fastcall aio_complete(struct kiocb *iocb, long res, long res2)
931{
932 struct kioctx *ctx = iocb->ki_ctx;
933 struct aio_ring_info *info;
934 struct aio_ring *ring;
935 struct io_event *event;
936 unsigned long flags;
937 unsigned long tail;
938 int ret;
939
Zach Brown20dcae32005-11-13 16:07:33 -0800940 /*
941 * Special case handling for sync iocbs:
942 * - events go directly into the iocb for fast handling
943 * - the sync task with the iocb in its stack holds the single iocb
944 * ref, no other paths have a way to get another ref
945 * - the sync task helpfully left a reference to itself in the iocb
Linus Torvalds1da177e2005-04-16 15:20:36 -0700946 */
947 if (is_sync_kiocb(iocb)) {
Zach Brown20dcae32005-11-13 16:07:33 -0800948 BUG_ON(iocb->ki_users != 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700949 iocb->ki_user_data = res;
Zach Brown20dcae32005-11-13 16:07:33 -0800950 iocb->ki_users = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951 wake_up_process(iocb->ki_obj.tsk);
Zach Brown20dcae32005-11-13 16:07:33 -0800952 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700953 }
954
955 info = &ctx->ring_info;
956
957 /* add a completion event to the ring buffer.
958 * must be done holding ctx->ctx_lock to prevent
959 * other code from messing with the tail
960 * pointer since we might be called from irq
961 * context.
962 */
963 spin_lock_irqsave(&ctx->ctx_lock, flags);
964
965 if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list))
966 list_del_init(&iocb->ki_run_list);
967
968 /*
969 * cancelled requests don't get events, userland was given one
970 * when the event got cancelled.
971 */
972 if (kiocbIsCancelled(iocb))
973 goto put_rq;
974
975 ring = kmap_atomic(info->ring_pages[0], KM_IRQ1);
976
977 tail = info->tail;
978 event = aio_ring_event(info, tail, KM_IRQ0);
Ken Chen4bf69b22005-05-01 08:59:15 -0700979 if (++tail >= info->nr)
980 tail = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981
982 event->obj = (u64)(unsigned long)iocb->ki_obj.user;
983 event->data = iocb->ki_user_data;
984 event->res = res;
985 event->res2 = res2;
986
987 dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n",
988 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
989 res, res2);
990
991 /* after flagging the request as done, we
992 * must never even look at it again
993 */
994 smp_wmb(); /* make event visible before updating tail */
995
996 info->tail = tail;
997 ring->tail = tail;
998
999 put_aio_ring_event(event, KM_IRQ0);
1000 kunmap_atomic(ring, KM_IRQ1);
1001
1002 pr_debug("added to ring %p at [%lu]\n", iocb, tail);
1003
Ken Chen644d3a02005-05-01 08:59:15 -07001004 pr_debug("%ld retries: %d of %d\n", iocb->ki_retried,
1005 iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006put_rq:
1007 /* everything turned out well, dispose of the aiocb. */
1008 ret = __aio_put_req(ctx, iocb);
1009
1010 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1011
1012 if (waitqueue_active(&ctx->wait))
1013 wake_up(&ctx->wait);
1014
1015 if (ret)
1016 put_ioctx(ctx);
1017
1018 return ret;
1019}
1020
1021/* aio_read_evt
1022 * Pull an event off of the ioctx's event ring. Returns the number of
1023 * events fetched (0 or 1 ;-)
1024 * FIXME: make this use cmpxchg.
1025 * TODO: make the ringbuffer user mmap()able (requires FIXME).
1026 */
1027static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent)
1028{
1029 struct aio_ring_info *info = &ioctx->ring_info;
1030 struct aio_ring *ring;
1031 unsigned long head;
1032 int ret = 0;
1033
1034 ring = kmap_atomic(info->ring_pages[0], KM_USER0);
1035 dprintk("in aio_read_evt h%lu t%lu m%lu\n",
1036 (unsigned long)ring->head, (unsigned long)ring->tail,
1037 (unsigned long)ring->nr);
1038
1039 if (ring->head == ring->tail)
1040 goto out;
1041
1042 spin_lock(&info->ring_lock);
1043
1044 head = ring->head % info->nr;
1045 if (head != ring->tail) {
1046 struct io_event *evp = aio_ring_event(info, head, KM_USER1);
1047 *ent = *evp;
1048 head = (head + 1) % info->nr;
1049 smp_mb(); /* finish reading the event before updatng the head */
1050 ring->head = head;
1051 ret = 1;
1052 put_aio_ring_event(evp, KM_USER1);
1053 }
1054 spin_unlock(&info->ring_lock);
1055
1056out:
1057 kunmap_atomic(ring, KM_USER0);
1058 dprintk("leaving aio_read_evt: %d h%lu t%lu\n", ret,
1059 (unsigned long)ring->head, (unsigned long)ring->tail);
1060 return ret;
1061}
1062
1063struct aio_timeout {
1064 struct timer_list timer;
1065 int timed_out;
1066 struct task_struct *p;
1067};
1068
1069static void timeout_func(unsigned long data)
1070{
1071 struct aio_timeout *to = (struct aio_timeout *)data;
1072
1073 to->timed_out = 1;
1074 wake_up_process(to->p);
1075}
1076
1077static inline void init_timeout(struct aio_timeout *to)
1078{
1079 init_timer(&to->timer);
1080 to->timer.data = (unsigned long)to;
1081 to->timer.function = timeout_func;
1082 to->timed_out = 0;
1083 to->p = current;
1084}
1085
1086static inline void set_timeout(long start_jiffies, struct aio_timeout *to,
1087 const struct timespec *ts)
1088{
1089 to->timer.expires = start_jiffies + timespec_to_jiffies(ts);
1090 if (time_after(to->timer.expires, jiffies))
1091 add_timer(&to->timer);
1092 else
1093 to->timed_out = 1;
1094}
1095
1096static inline void clear_timeout(struct aio_timeout *to)
1097{
1098 del_singleshot_timer_sync(&to->timer);
1099}
1100
1101static int read_events(struct kioctx *ctx,
1102 long min_nr, long nr,
1103 struct io_event __user *event,
1104 struct timespec __user *timeout)
1105{
1106 long start_jiffies = jiffies;
1107 struct task_struct *tsk = current;
1108 DECLARE_WAITQUEUE(wait, tsk);
1109 int ret;
1110 int i = 0;
1111 struct io_event ent;
1112 struct aio_timeout to;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001113 int retry = 0;
1114
1115 /* needed to zero any padding within an entry (there shouldn't be
1116 * any, but C is fun!
1117 */
1118 memset(&ent, 0, sizeof(ent));
1119retry:
1120 ret = 0;
1121 while (likely(i < nr)) {
1122 ret = aio_read_evt(ctx, &ent);
1123 if (unlikely(ret <= 0))
1124 break;
1125
1126 dprintk("read event: %Lx %Lx %Lx %Lx\n",
1127 ent.data, ent.obj, ent.res, ent.res2);
1128
1129 /* Could we split the check in two? */
1130 ret = -EFAULT;
1131 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
1132 dprintk("aio: lost an event due to EFAULT.\n");
1133 break;
1134 }
1135 ret = 0;
1136
1137 /* Good, event copied to userland, update counts. */
1138 event ++;
1139 i ++;
1140 }
1141
1142 if (min_nr <= i)
1143 return i;
1144 if (ret)
1145 return ret;
1146
1147 /* End fast path */
1148
1149 /* racey check, but it gets redone */
1150 if (!retry && unlikely(!list_empty(&ctx->run_list))) {
1151 retry = 1;
1152 aio_run_all_iocbs(ctx);
1153 goto retry;
1154 }
1155
1156 init_timeout(&to);
1157 if (timeout) {
1158 struct timespec ts;
1159 ret = -EFAULT;
1160 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
1161 goto out;
1162
1163 set_timeout(start_jiffies, &to, &ts);
1164 }
1165
1166 while (likely(i < nr)) {
1167 add_wait_queue_exclusive(&ctx->wait, &wait);
1168 do {
1169 set_task_state(tsk, TASK_INTERRUPTIBLE);
1170 ret = aio_read_evt(ctx, &ent);
1171 if (ret)
1172 break;
1173 if (min_nr <= i)
1174 break;
1175 ret = 0;
1176 if (to.timed_out) /* Only check after read evt */
1177 break;
1178 schedule();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001179 if (signal_pending(tsk)) {
1180 ret = -EINTR;
1181 break;
1182 }
1183 /*ret = aio_read_evt(ctx, &ent);*/
1184 } while (1) ;
1185
1186 set_task_state(tsk, TASK_RUNNING);
1187 remove_wait_queue(&ctx->wait, &wait);
1188
1189 if (unlikely(ret <= 0))
1190 break;
1191
1192 ret = -EFAULT;
1193 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
1194 dprintk("aio: lost an event due to EFAULT.\n");
1195 break;
1196 }
1197
1198 /* Good, event copied to userland, update counts. */
1199 event ++;
1200 i ++;
1201 }
1202
1203 if (timeout)
1204 clear_timeout(&to);
1205out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206 return i ? i : ret;
1207}
1208
1209/* Take an ioctx and remove it from the list of ioctx's. Protects
1210 * against races with itself via ->dead.
1211 */
1212static void io_destroy(struct kioctx *ioctx)
1213{
1214 struct mm_struct *mm = current->mm;
1215 struct kioctx **tmp;
1216 int was_dead;
1217
1218 /* delete the entry from the list is someone else hasn't already */
1219 write_lock(&mm->ioctx_list_lock);
1220 was_dead = ioctx->dead;
1221 ioctx->dead = 1;
1222 for (tmp = &mm->ioctx_list; *tmp && *tmp != ioctx;
1223 tmp = &(*tmp)->next)
1224 ;
1225 if (*tmp)
1226 *tmp = ioctx->next;
1227 write_unlock(&mm->ioctx_list_lock);
1228
1229 dprintk("aio_release(%p)\n", ioctx);
1230 if (likely(!was_dead))
1231 put_ioctx(ioctx); /* twice for the list */
1232
1233 aio_cancel_all(ioctx);
1234 wait_for_all_aios(ioctx);
1235 put_ioctx(ioctx); /* once for the lookup */
1236}
1237
1238/* sys_io_setup:
1239 * Create an aio_context capable of receiving at least nr_events.
1240 * ctxp must not point to an aio_context that already exists, and
1241 * must be initialized to 0 prior to the call. On successful
1242 * creation of the aio_context, *ctxp is filled in with the resulting
1243 * handle. May fail with -EINVAL if *ctxp is not initialized,
1244 * if the specified nr_events exceeds internal limits. May fail
1245 * with -EAGAIN if the specified nr_events exceeds the user's limit
1246 * of available events. May fail with -ENOMEM if insufficient kernel
1247 * resources are available. May fail with -EFAULT if an invalid
1248 * pointer is passed for ctxp. Will fail with -ENOSYS if not
1249 * implemented.
1250 */
1251asmlinkage long sys_io_setup(unsigned nr_events, aio_context_t __user *ctxp)
1252{
1253 struct kioctx *ioctx = NULL;
1254 unsigned long ctx;
1255 long ret;
1256
1257 ret = get_user(ctx, ctxp);
1258 if (unlikely(ret))
1259 goto out;
1260
1261 ret = -EINVAL;
Zach Brownd55b5fd2005-11-07 00:59:31 -08001262 if (unlikely(ctx || nr_events == 0)) {
1263 pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
1264 ctx, nr_events);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001265 goto out;
1266 }
1267
1268 ioctx = ioctx_alloc(nr_events);
1269 ret = PTR_ERR(ioctx);
1270 if (!IS_ERR(ioctx)) {
1271 ret = put_user(ioctx->user_id, ctxp);
1272 if (!ret)
1273 return 0;
1274
1275 get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */
1276 io_destroy(ioctx);
1277 }
1278
1279out:
1280 return ret;
1281}
1282
1283/* sys_io_destroy:
1284 * Destroy the aio_context specified. May cancel any outstanding
1285 * AIOs and block on completion. Will fail with -ENOSYS if not
1286 * implemented. May fail with -EFAULT if the context pointed to
1287 * is invalid.
1288 */
1289asmlinkage long sys_io_destroy(aio_context_t ctx)
1290{
1291 struct kioctx *ioctx = lookup_ioctx(ctx);
1292 if (likely(NULL != ioctx)) {
1293 io_destroy(ioctx);
1294 return 0;
1295 }
1296 pr_debug("EINVAL: io_destroy: invalid context id\n");
1297 return -EINVAL;
1298}
1299
1300/*
Zach Brown897f15f2005-09-30 11:58:55 -07001301 * aio_p{read,write} are the default ki_retry methods for
1302 * IO_CMD_P{READ,WRITE}. They maintains kiocb retry state around potentially
1303 * multiple calls to f_op->aio_read(). They loop around partial progress
1304 * instead of returning -EIOCBRETRY because they don't have the means to call
1305 * kick_iocb().
Linus Torvalds1da177e2005-04-16 15:20:36 -07001306 */
1307static ssize_t aio_pread(struct kiocb *iocb)
1308{
1309 struct file *file = iocb->ki_filp;
1310 struct address_space *mapping = file->f_mapping;
1311 struct inode *inode = mapping->host;
1312 ssize_t ret = 0;
1313
Zach Brown897f15f2005-09-30 11:58:55 -07001314 do {
1315 ret = file->f_op->aio_read(iocb, iocb->ki_buf,
1316 iocb->ki_left, iocb->ki_pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001317 /*
Zach Brown897f15f2005-09-30 11:58:55 -07001318 * Can't just depend on iocb->ki_left to determine
1319 * whether we are done. This may have been a short read.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001320 */
Zach Brown897f15f2005-09-30 11:58:55 -07001321 if (ret > 0) {
1322 iocb->ki_buf += ret;
1323 iocb->ki_left -= ret;
1324 }
1325
1326 /*
1327 * For pipes and sockets we return once we have some data; for
1328 * regular files we retry till we complete the entire read or
1329 * find that we can't read any more data (e.g short reads).
1330 */
Zach Brown353fb072005-09-30 11:58:56 -07001331 } while (ret > 0 && iocb->ki_left > 0 &&
Zach Brown897f15f2005-09-30 11:58:55 -07001332 !S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333
1334 /* This means we must have transferred all that we could */
1335 /* No need to retry anymore */
1336 if ((ret == 0) || (iocb->ki_left == 0))
1337 ret = iocb->ki_nbytes - iocb->ki_left;
1338
1339 return ret;
1340}
1341
Zach Brown897f15f2005-09-30 11:58:55 -07001342/* see aio_pread() */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343static ssize_t aio_pwrite(struct kiocb *iocb)
1344{
1345 struct file *file = iocb->ki_filp;
1346 ssize_t ret = 0;
1347
Zach Brown897f15f2005-09-30 11:58:55 -07001348 do {
1349 ret = file->f_op->aio_write(iocb, iocb->ki_buf,
1350 iocb->ki_left, iocb->ki_pos);
1351 if (ret > 0) {
1352 iocb->ki_buf += ret;
1353 iocb->ki_left -= ret;
1354 }
Zach Brown353fb072005-09-30 11:58:56 -07001355 } while (ret > 0 && iocb->ki_left > 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001356
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357 if ((ret == 0) || (iocb->ki_left == 0))
1358 ret = iocb->ki_nbytes - iocb->ki_left;
1359
1360 return ret;
1361}
1362
1363static ssize_t aio_fdsync(struct kiocb *iocb)
1364{
1365 struct file *file = iocb->ki_filp;
1366 ssize_t ret = -EINVAL;
1367
1368 if (file->f_op->aio_fsync)
1369 ret = file->f_op->aio_fsync(iocb, 1);
1370 return ret;
1371}
1372
1373static ssize_t aio_fsync(struct kiocb *iocb)
1374{
1375 struct file *file = iocb->ki_filp;
1376 ssize_t ret = -EINVAL;
1377
1378 if (file->f_op->aio_fsync)
1379 ret = file->f_op->aio_fsync(iocb, 0);
1380 return ret;
1381}
1382
1383/*
1384 * aio_setup_iocb:
1385 * Performs the initial checks and aio retry method
1386 * setup for the kiocb at the time of io submission.
1387 */
Adrian Bunk25ee7e32005-04-25 08:18:14 -07001388static ssize_t aio_setup_iocb(struct kiocb *kiocb)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389{
1390 struct file *file = kiocb->ki_filp;
1391 ssize_t ret = 0;
1392
1393 switch (kiocb->ki_opcode) {
1394 case IOCB_CMD_PREAD:
1395 ret = -EBADF;
1396 if (unlikely(!(file->f_mode & FMODE_READ)))
1397 break;
1398 ret = -EFAULT;
1399 if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf,
1400 kiocb->ki_left)))
1401 break;
Kostik Belousov8766ce42005-10-23 12:57:13 -07001402 ret = security_file_permission(file, MAY_READ);
1403 if (unlikely(ret))
1404 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405 ret = -EINVAL;
1406 if (file->f_op->aio_read)
1407 kiocb->ki_retry = aio_pread;
1408 break;
1409 case IOCB_CMD_PWRITE:
1410 ret = -EBADF;
1411 if (unlikely(!(file->f_mode & FMODE_WRITE)))
1412 break;
1413 ret = -EFAULT;
1414 if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf,
1415 kiocb->ki_left)))
1416 break;
Kostik Belousov8766ce42005-10-23 12:57:13 -07001417 ret = security_file_permission(file, MAY_WRITE);
1418 if (unlikely(ret))
1419 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001420 ret = -EINVAL;
1421 if (file->f_op->aio_write)
1422 kiocb->ki_retry = aio_pwrite;
1423 break;
1424 case IOCB_CMD_FDSYNC:
1425 ret = -EINVAL;
1426 if (file->f_op->aio_fsync)
1427 kiocb->ki_retry = aio_fdsync;
1428 break;
1429 case IOCB_CMD_FSYNC:
1430 ret = -EINVAL;
1431 if (file->f_op->aio_fsync)
1432 kiocb->ki_retry = aio_fsync;
1433 break;
1434 default:
1435 dprintk("EINVAL: io_submit: no operation provided\n");
1436 ret = -EINVAL;
1437 }
1438
1439 if (!kiocb->ki_retry)
1440 return ret;
1441
1442 return 0;
1443}
1444
1445/*
1446 * aio_wake_function:
1447 * wait queue callback function for aio notification,
1448 * Simply triggers a retry of the operation via kick_iocb.
1449 *
1450 * This callback is specified in the wait queue entry in
1451 * a kiocb (current->io_wait points to this wait queue
1452 * entry when an aio operation executes; it is used
1453 * instead of a synchronous wait when an i/o blocking
1454 * condition is encountered during aio).
1455 *
1456 * Note:
1457 * This routine is executed with the wait queue lock held.
1458 * Since kick_iocb acquires iocb->ctx->ctx_lock, it nests
1459 * the ioctx lock inside the wait queue lock. This is safe
1460 * because this callback isn't used for wait queues which
1461 * are nested inside ioctx lock (i.e. ctx->wait)
1462 */
Adrian Bunk25ee7e32005-04-25 08:18:14 -07001463static int aio_wake_function(wait_queue_t *wait, unsigned mode,
1464 int sync, void *key)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001465{
1466 struct kiocb *iocb = container_of(wait, struct kiocb, ki_wait);
1467
1468 list_del_init(&wait->task_list);
1469 kick_iocb(iocb);
1470 return 1;
1471}
1472
1473int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1474 struct iocb *iocb)
1475{
1476 struct kiocb *req;
1477 struct file *file;
1478 ssize_t ret;
1479
1480 /* enforce forwards compatibility on users */
1481 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2 ||
1482 iocb->aio_reserved3)) {
1483 pr_debug("EINVAL: io_submit: reserve field set\n");
1484 return -EINVAL;
1485 }
1486
1487 /* prevent overflows */
1488 if (unlikely(
1489 (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
1490 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
1491 ((ssize_t)iocb->aio_nbytes < 0)
1492 )) {
1493 pr_debug("EINVAL: io_submit: overflow check\n");
1494 return -EINVAL;
1495 }
1496
1497 file = fget(iocb->aio_fildes);
1498 if (unlikely(!file))
1499 return -EBADF;
1500
1501 req = aio_get_req(ctx); /* returns with 2 references to req */
1502 if (unlikely(!req)) {
1503 fput(file);
1504 return -EAGAIN;
1505 }
1506
1507 req->ki_filp = file;
Ken Chen212079c2005-05-01 08:59:15 -07001508 ret = put_user(req->ki_key, &user_iocb->aio_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001509 if (unlikely(ret)) {
1510 dprintk("EFAULT: aio_key\n");
1511 goto out_put_req;
1512 }
1513
1514 req->ki_obj.user = user_iocb;
1515 req->ki_user_data = iocb->aio_data;
1516 req->ki_pos = iocb->aio_offset;
1517
1518 req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf;
1519 req->ki_left = req->ki_nbytes = iocb->aio_nbytes;
1520 req->ki_opcode = iocb->aio_lio_opcode;
1521 init_waitqueue_func_entry(&req->ki_wait, aio_wake_function);
1522 INIT_LIST_HEAD(&req->ki_wait.task_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001523 req->ki_retried = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001524
1525 ret = aio_setup_iocb(req);
1526
1527 if (ret)
1528 goto out_put_req;
1529
1530 spin_lock_irq(&ctx->ctx_lock);
Benjamin LaHaiseac0b1bc2005-09-09 13:02:09 -07001531 aio_run_iocb(req);
Benjamin LaHaiseac0b1bc2005-09-09 13:02:09 -07001532 if (!list_empty(&ctx->run_list)) {
Ken Chen954d3e92005-05-01 08:59:16 -07001533 /* drain the run list */
1534 while (__aio_run_iocbs(ctx))
1535 ;
1536 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001537 spin_unlock_irq(&ctx->ctx_lock);
1538 aio_put_req(req); /* drop extra ref to req */
1539 return 0;
1540
1541out_put_req:
1542 aio_put_req(req); /* drop extra ref to req */
1543 aio_put_req(req); /* drop i/o ref to req */
1544 return ret;
1545}
1546
1547/* sys_io_submit:
1548 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1549 * the number of iocbs queued. May return -EINVAL if the aio_context
1550 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1551 * *iocbpp[0] is not properly initialized, if the operation specified
1552 * is invalid for the file descriptor in the iocb. May fail with
1553 * -EFAULT if any of the data structures point to invalid data. May
1554 * fail with -EBADF if the file descriptor specified in the first
1555 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1556 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1557 * fail with -ENOSYS if not implemented.
1558 */
1559asmlinkage long sys_io_submit(aio_context_t ctx_id, long nr,
1560 struct iocb __user * __user *iocbpp)
1561{
1562 struct kioctx *ctx;
1563 long ret = 0;
1564 int i;
1565
1566 if (unlikely(nr < 0))
1567 return -EINVAL;
1568
1569 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1570 return -EFAULT;
1571
1572 ctx = lookup_ioctx(ctx_id);
1573 if (unlikely(!ctx)) {
1574 pr_debug("EINVAL: io_submit: invalid context id\n");
1575 return -EINVAL;
1576 }
1577
1578 /*
1579 * AKPM: should this return a partial result if some of the IOs were
1580 * successfully submitted?
1581 */
1582 for (i=0; i<nr; i++) {
1583 struct iocb __user *user_iocb;
1584 struct iocb tmp;
1585
1586 if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1587 ret = -EFAULT;
1588 break;
1589 }
1590
1591 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1592 ret = -EFAULT;
1593 break;
1594 }
1595
1596 ret = io_submit_one(ctx, user_iocb, &tmp);
1597 if (ret)
1598 break;
1599 }
1600
1601 put_ioctx(ctx);
1602 return i ? i : ret;
1603}
1604
1605/* lookup_kiocb
1606 * Finds a given iocb for cancellation.
1607 * MUST be called with ctx->ctx_lock held.
1608 */
Adrian Bunk25ee7e32005-04-25 08:18:14 -07001609static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
1610 u32 key)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001611{
1612 struct list_head *pos;
1613 /* TODO: use a hash or array, this sucks. */
1614 list_for_each(pos, &ctx->active_reqs) {
1615 struct kiocb *kiocb = list_kiocb(pos);
1616 if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key)
1617 return kiocb;
1618 }
1619 return NULL;
1620}
1621
1622/* sys_io_cancel:
1623 * Attempts to cancel an iocb previously passed to io_submit. If
1624 * the operation is successfully cancelled, the resulting event is
1625 * copied into the memory pointed to by result without being placed
1626 * into the completion queue and 0 is returned. May fail with
1627 * -EFAULT if any of the data structures pointed to are invalid.
1628 * May fail with -EINVAL if aio_context specified by ctx_id is
1629 * invalid. May fail with -EAGAIN if the iocb specified was not
1630 * cancelled. Will fail with -ENOSYS if not implemented.
1631 */
1632asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb,
1633 struct io_event __user *result)
1634{
1635 int (*cancel)(struct kiocb *iocb, struct io_event *res);
1636 struct kioctx *ctx;
1637 struct kiocb *kiocb;
1638 u32 key;
1639 int ret;
1640
1641 ret = get_user(key, &iocb->aio_key);
1642 if (unlikely(ret))
1643 return -EFAULT;
1644
1645 ctx = lookup_ioctx(ctx_id);
1646 if (unlikely(!ctx))
1647 return -EINVAL;
1648
1649 spin_lock_irq(&ctx->ctx_lock);
1650 ret = -EAGAIN;
1651 kiocb = lookup_kiocb(ctx, iocb, key);
1652 if (kiocb && kiocb->ki_cancel) {
1653 cancel = kiocb->ki_cancel;
1654 kiocb->ki_users ++;
1655 kiocbSetCancelled(kiocb);
1656 } else
1657 cancel = NULL;
1658 spin_unlock_irq(&ctx->ctx_lock);
1659
1660 if (NULL != cancel) {
1661 struct io_event tmp;
1662 pr_debug("calling cancel\n");
1663 memset(&tmp, 0, sizeof(tmp));
1664 tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user;
1665 tmp.data = kiocb->ki_user_data;
1666 ret = cancel(kiocb, &tmp);
1667 if (!ret) {
1668 /* Cancellation succeeded -- copy the result
1669 * into the user's buffer.
1670 */
1671 if (copy_to_user(result, &tmp, sizeof(tmp)))
1672 ret = -EFAULT;
1673 }
1674 } else
Wendy Cheng8f582022005-09-09 13:02:08 -07001675 ret = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001676
1677 put_ioctx(ctx);
1678
1679 return ret;
1680}
1681
1682/* io_getevents:
1683 * Attempts to read at least min_nr events and up to nr events from
1684 * the completion queue for the aio_context specified by ctx_id. May
1685 * fail with -EINVAL if ctx_id is invalid, if min_nr is out of range,
1686 * if nr is out of range, if when is out of range. May fail with
1687 * -EFAULT if any of the memory specified to is invalid. May return
1688 * 0 or < min_nr if no events are available and the timeout specified
1689 * by when has elapsed, where when == NULL specifies an infinite
1690 * timeout. Note that the timeout pointed to by when is relative and
1691 * will be updated if not NULL and the operation blocks. Will fail
1692 * with -ENOSYS if not implemented.
1693 */
1694asmlinkage long sys_io_getevents(aio_context_t ctx_id,
1695 long min_nr,
1696 long nr,
1697 struct io_event __user *events,
1698 struct timespec __user *timeout)
1699{
1700 struct kioctx *ioctx = lookup_ioctx(ctx_id);
1701 long ret = -EINVAL;
1702
1703 if (likely(ioctx)) {
1704 if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0))
1705 ret = read_events(ioctx, min_nr, nr, events, timeout);
1706 put_ioctx(ioctx);
1707 }
1708
1709 return ret;
1710}
1711
1712__initcall(aio_setup);
1713
1714EXPORT_SYMBOL(aio_complete);
1715EXPORT_SYMBOL(aio_put_req);
1716EXPORT_SYMBOL(wait_on_sync_kiocb);