2 * An async IO implementation for Linux
3 * Written by Benjamin LaHaise <bcrl@kvack.org>
5 * Implements an efficient asynchronous io interface.
7 * Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved.
9 * See ../COPYING for licensing terms.
11 #define pr_fmt(fmt) "%s: " fmt, __func__
13 #include <linux/kernel.h>
14 #include <linux/init.h>
15 #include <linux/errno.h>
16 #include <linux/time.h>
17 #include <linux/aio_abi.h>
18 #include <linux/export.h>
19 #include <linux/syscalls.h>
20 #include <linux/backing-dev.h>
21 #include <linux/uio.h>
23 #include <linux/sched.h>
25 #include <linux/file.h>
27 #include <linux/mman.h>
28 #include <linux/mmu_context.h>
29 #include <linux/slab.h>
30 #include <linux/timer.h>
31 #include <linux/aio.h>
32 #include <linux/highmem.h>
33 #include <linux/workqueue.h>
34 #include <linux/security.h>
35 #include <linux/eventfd.h>
36 #include <linux/blkdev.h>
37 #include <linux/compat.h>
39 #include <asm/kmap_types.h>
40 #include <asm/uaccess.h>
44 #define AIO_RING_MAGIC 0xa10a10a1
45 #define AIO_RING_COMPAT_FEATURES 1
46 #define AIO_RING_INCOMPAT_FEATURES 0
48 unsigned id; /* kernel internal index number */
49 unsigned nr; /* number of io_events */
54 unsigned compat_features;
55 unsigned incompat_features;
56 unsigned header_length; /* size of aio_ring */
59 struct io_event io_events[0];
60 }; /* 128 bytes + ring size */
62 #define AIO_RING_PAGES 8
68 /* This needs improving */
69 unsigned long user_id;
70 struct hlist_node list;
73 * This is what userspace passed to io_setup(), it's not used for
74 * anything but counting against the global max_reqs quota.
76 * The real limit is nr_events - 1, which will be larger (see
81 /* Size of ringbuffer, in units of struct io_event */
84 unsigned long mmap_base;
85 unsigned long mmap_size;
87 struct page **ring_pages;
90 struct rcu_head rcu_head;
91 struct work_struct rcu_work;
95 } ____cacheline_aligned_in_smp;
99 struct list_head active_reqs; /* used for cancellation */
100 } ____cacheline_aligned_in_smp;
103 struct mutex ring_lock;
104 wait_queue_head_t wait;
105 } ____cacheline_aligned_in_smp;
109 spinlock_t completion_lock;
110 } ____cacheline_aligned_in_smp;
112 struct page *internal_pages[AIO_RING_PAGES];
115 /*------ sysctl variables----*/
116 static DEFINE_SPINLOCK(aio_nr_lock);
117 unsigned long aio_nr; /* current system wide number of aio requests */
118 unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
119 /*----end sysctl variables---*/
121 static struct kmem_cache *kiocb_cachep;
122 static struct kmem_cache *kioctx_cachep;
125 * Creates the slab caches used by the aio routines, panic on
126 * failure as this is done early during the boot sequence.
128 static int __init aio_setup(void)
130 kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
131 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
133 pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
137 __initcall(aio_setup);
139 static void aio_free_ring(struct kioctx *ctx)
143 for (i = 0; i < ctx->nr_pages; i++)
144 put_page(ctx->ring_pages[i]);
146 if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages)
147 kfree(ctx->ring_pages);
150 static int aio_setup_ring(struct kioctx *ctx)
152 struct aio_ring *ring;
153 unsigned nr_events = ctx->max_reqs;
154 struct mm_struct *mm = current->mm;
155 unsigned long size, populate;
158 /* Compensate for the ring buffer's head/tail overlap entry */
159 nr_events += 2; /* 1 is required, 2 for good luck */
161 size = sizeof(struct aio_ring);
162 size += sizeof(struct io_event) * nr_events;
163 nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT;
168 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event);
171 ctx->ring_pages = ctx->internal_pages;
172 if (nr_pages > AIO_RING_PAGES) {
173 ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
175 if (!ctx->ring_pages)
179 ctx->mmap_size = nr_pages * PAGE_SIZE;
180 pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
181 down_write(&mm->mmap_sem);
182 ctx->mmap_base = do_mmap_pgoff(NULL, 0, ctx->mmap_size,
183 PROT_READ|PROT_WRITE,
184 MAP_ANONYMOUS|MAP_PRIVATE, 0, &populate);
185 if (IS_ERR((void *)ctx->mmap_base)) {
186 up_write(&mm->mmap_sem);
192 pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
193 ctx->nr_pages = get_user_pages(current, mm, ctx->mmap_base, nr_pages,
194 1, 0, ctx->ring_pages, NULL);
195 up_write(&mm->mmap_sem);
197 if (unlikely(ctx->nr_pages != nr_pages)) {
202 mm_populate(ctx->mmap_base, populate);
204 ctx->user_id = ctx->mmap_base;
205 ctx->nr_events = nr_events; /* trusted copy */
207 ring = kmap_atomic(ctx->ring_pages[0]);
208 ring->nr = nr_events; /* user copy */
209 ring->id = ctx->user_id;
210 ring->head = ring->tail = 0;
211 ring->magic = AIO_RING_MAGIC;
212 ring->compat_features = AIO_RING_COMPAT_FEATURES;
213 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
214 ring->header_length = sizeof(struct aio_ring);
216 flush_dcache_page(ctx->ring_pages[0]);
221 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
222 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
223 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
225 void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel)
227 struct kioctx *ctx = req->ki_ctx;
230 spin_lock_irqsave(&ctx->ctx_lock, flags);
232 if (!req->ki_list.next)
233 list_add(&req->ki_list, &ctx->active_reqs);
235 req->ki_cancel = cancel;
237 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
239 EXPORT_SYMBOL(kiocb_set_cancel_fn);
241 static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb,
242 struct io_event *res)
244 kiocb_cancel_fn *old, *cancel;
248 * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
249 * actually has a cancel function, hence the cmpxchg()
252 cancel = ACCESS_ONCE(kiocb->ki_cancel);
254 if (!cancel || cancel == KIOCB_CANCELLED)
258 cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
259 } while (cancel != old);
261 atomic_inc(&kiocb->ki_users);
262 spin_unlock_irq(&ctx->ctx_lock);
264 memset(res, 0, sizeof(*res));
265 res->obj = (u64)(unsigned long)kiocb->ki_obj.user;
266 res->data = kiocb->ki_user_data;
267 ret = cancel(kiocb, res);
269 spin_lock_irq(&ctx->ctx_lock);
274 static void free_ioctx_rcu(struct rcu_head *head)
276 struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
277 kmem_cache_free(kioctx_cachep, ctx);
281 * When this function runs, the kioctx has been removed from the "hash table"
282 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
283 * now it's safe to cancel any that need to be.
285 static void free_ioctx(struct kioctx *ctx)
287 struct aio_ring *ring;
290 unsigned head, avail;
292 spin_lock_irq(&ctx->ctx_lock);
294 while (!list_empty(&ctx->active_reqs)) {
295 req = list_first_entry(&ctx->active_reqs,
296 struct kiocb, ki_list);
298 list_del_init(&req->ki_list);
299 kiocb_cancel(ctx, req, &res);
302 spin_unlock_irq(&ctx->ctx_lock);
304 ring = kmap_atomic(ctx->ring_pages[0]);
308 while (atomic_read(&ctx->reqs_active) > 0) {
309 wait_event(ctx->wait,
311 atomic_read(&ctx->reqs_active) <= 0);
313 avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head;
315 atomic_sub(avail, &ctx->reqs_active);
317 head %= ctx->nr_events;
320 WARN_ON(atomic_read(&ctx->reqs_active) < 0);
324 pr_debug("freeing %p\n", ctx);
327 * Here the call_rcu() is between the wait_event() for reqs_active to
328 * hit 0, and freeing the ioctx.
330 * aio_complete() decrements reqs_active, but it has to touch the ioctx
331 * after to issue a wakeup so we use rcu.
333 call_rcu(&ctx->rcu_head, free_ioctx_rcu);
336 static void put_ioctx(struct kioctx *ctx)
338 if (unlikely(atomic_dec_and_test(&ctx->users)))
343 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
345 static struct kioctx *ioctx_alloc(unsigned nr_events)
347 struct mm_struct *mm = current->mm;
351 /* Prevent overflows */
352 if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
353 (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
354 pr_debug("ENOMEM: nr_events too high\n");
355 return ERR_PTR(-EINVAL);
358 if (!nr_events || (unsigned long)nr_events > aio_max_nr)
359 return ERR_PTR(-EAGAIN);
361 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
363 return ERR_PTR(-ENOMEM);
365 ctx->max_reqs = nr_events;
367 atomic_set(&ctx->users, 2);
368 atomic_set(&ctx->dead, 0);
369 spin_lock_init(&ctx->ctx_lock);
370 spin_lock_init(&ctx->completion_lock);
371 mutex_init(&ctx->ring_lock);
372 init_waitqueue_head(&ctx->wait);
374 INIT_LIST_HEAD(&ctx->active_reqs);
376 if (aio_setup_ring(ctx) < 0)
379 /* limit the number of system wide aios */
380 spin_lock(&aio_nr_lock);
381 if (aio_nr + nr_events > aio_max_nr ||
382 aio_nr + nr_events < aio_nr) {
383 spin_unlock(&aio_nr_lock);
386 aio_nr += ctx->max_reqs;
387 spin_unlock(&aio_nr_lock);
389 /* now link into global list. */
390 spin_lock(&mm->ioctx_lock);
391 hlist_add_head_rcu(&ctx->list, &mm->ioctx_list);
392 spin_unlock(&mm->ioctx_lock);
394 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
395 ctx, ctx->user_id, mm, ctx->nr_events);
402 kmem_cache_free(kioctx_cachep, ctx);
403 pr_debug("error allocating ioctx %d\n", err);
407 static void kill_ioctx_work(struct work_struct *work)
409 struct kioctx *ctx = container_of(work, struct kioctx, rcu_work);
411 wake_up_all(&ctx->wait);
415 static void kill_ioctx_rcu(struct rcu_head *head)
417 struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
419 INIT_WORK(&ctx->rcu_work, kill_ioctx_work);
420 schedule_work(&ctx->rcu_work);
424 * Cancels all outstanding aio requests on an aio context. Used
425 * when the processes owning a context have all exited to encourage
426 * the rapid destruction of the kioctx.
428 static void kill_ioctx(struct kioctx *ctx)
430 if (!atomic_xchg(&ctx->dead, 1)) {
431 hlist_del_rcu(&ctx->list);
434 * It'd be more correct to do this in free_ioctx(), after all
435 * the outstanding kiocbs have finished - but by then io_destroy
436 * has already returned, so io_setup() could potentially return
437 * -EAGAIN with no ioctxs actually in use (as far as userspace
440 spin_lock(&aio_nr_lock);
441 BUG_ON(aio_nr - ctx->max_reqs > aio_nr);
442 aio_nr -= ctx->max_reqs;
443 spin_unlock(&aio_nr_lock);
446 vm_munmap(ctx->mmap_base, ctx->mmap_size);
448 /* Between hlist_del_rcu() and dropping the initial ref */
449 call_rcu(&ctx->rcu_head, kill_ioctx_rcu);
453 /* wait_on_sync_kiocb:
454 * Waits on the given sync kiocb to complete.
456 ssize_t wait_on_sync_kiocb(struct kiocb *iocb)
458 while (atomic_read(&iocb->ki_users)) {
459 set_current_state(TASK_UNINTERRUPTIBLE);
460 if (!atomic_read(&iocb->ki_users))
464 __set_current_state(TASK_RUNNING);
465 return iocb->ki_user_data;
467 EXPORT_SYMBOL(wait_on_sync_kiocb);
470 * exit_aio: called when the last user of mm goes away. At this point, there is
471 * no way for any new requests to be submited or any of the io_* syscalls to be
472 * called on the context.
474 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
477 void exit_aio(struct mm_struct *mm)
480 struct hlist_node *n;
482 hlist_for_each_entry_safe(ctx, n, &mm->ioctx_list, list) {
483 if (1 != atomic_read(&ctx->users))
485 "exit_aio:ioctx still alive: %d %d %d\n",
486 atomic_read(&ctx->users),
487 atomic_read(&ctx->dead),
488 atomic_read(&ctx->reqs_active));
490 * We don't need to bother with munmap() here -
491 * exit_mmap(mm) is coming and it'll unmap everything.
492 * Since aio_free_ring() uses non-zero ->mmap_size
493 * as indicator that it needs to unmap the area,
494 * just set it to 0; aio_free_ring() is the only
495 * place that uses ->mmap_size, so it's safe.
504 * Allocate a slot for an aio request. Increments the ki_users count
505 * of the kioctx so that the kioctx stays around until all requests are
506 * complete. Returns NULL if no requests are free.
508 * Returns with kiocb->ki_users set to 2. The io submit code path holds
509 * an extra reference while submitting the i/o.
510 * This prevents races between the aio code path referencing the
511 * req (after submitting it) and aio_complete() freeing the req.
513 static inline struct kiocb *aio_get_req(struct kioctx *ctx)
517 if (atomic_read(&ctx->reqs_active) >= ctx->nr_events)
520 if (atomic_inc_return(&ctx->reqs_active) > ctx->nr_events - 1)
523 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
527 atomic_set(&req->ki_users, 2);
532 atomic_dec(&ctx->reqs_active);
536 static void kiocb_free(struct kiocb *req)
540 if (req->ki_eventfd != NULL)
541 eventfd_ctx_put(req->ki_eventfd);
544 if (req->ki_iovec != &req->ki_inline_vec)
545 kfree(req->ki_iovec);
546 kmem_cache_free(kiocb_cachep, req);
549 void aio_put_req(struct kiocb *req)
551 if (atomic_dec_and_test(&req->ki_users))
554 EXPORT_SYMBOL(aio_put_req);
556 static struct kioctx *lookup_ioctx(unsigned long ctx_id)
558 struct mm_struct *mm = current->mm;
559 struct kioctx *ctx, *ret = NULL;
563 hlist_for_each_entry_rcu(ctx, &mm->ioctx_list, list) {
564 if (ctx->user_id == ctx_id) {
565 atomic_inc(&ctx->users);
576 * Called when the io request on the given iocb is complete.
578 void aio_complete(struct kiocb *iocb, long res, long res2)
580 struct kioctx *ctx = iocb->ki_ctx;
581 struct aio_ring *ring;
582 struct io_event *ev_page, *event;
587 * Special case handling for sync iocbs:
588 * - events go directly into the iocb for fast handling
589 * - the sync task with the iocb in its stack holds the single iocb
590 * ref, no other paths have a way to get another ref
591 * - the sync task helpfully left a reference to itself in the iocb
593 if (is_sync_kiocb(iocb)) {
594 BUG_ON(atomic_read(&iocb->ki_users) != 1);
595 iocb->ki_user_data = res;
596 atomic_set(&iocb->ki_users, 0);
597 wake_up_process(iocb->ki_obj.tsk);
602 * Take rcu_read_lock() in case the kioctx is being destroyed, as we
603 * need to issue a wakeup after decrementing reqs_active.
607 if (iocb->ki_list.next) {
610 spin_lock_irqsave(&ctx->ctx_lock, flags);
611 list_del(&iocb->ki_list);
612 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
616 * cancelled requests don't get events, userland was given one
617 * when the event got cancelled.
619 if (unlikely(xchg(&iocb->ki_cancel,
620 KIOCB_CANCELLED) == KIOCB_CANCELLED)) {
621 atomic_dec(&ctx->reqs_active);
622 /* Still need the wake_up in case free_ioctx is waiting */
627 * Add a completion event to the ring buffer. Must be done holding
628 * ctx->completion_lock to prevent other code from messing with the tail
629 * pointer since we might be called from irq context.
631 spin_lock_irqsave(&ctx->completion_lock, flags);
634 pos = tail + AIO_EVENTS_OFFSET;
636 if (++tail >= ctx->nr_events)
639 ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
640 event = ev_page + pos % AIO_EVENTS_PER_PAGE;
642 event->obj = (u64)(unsigned long)iocb->ki_obj.user;
643 event->data = iocb->ki_user_data;
647 kunmap_atomic(ev_page);
648 flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
650 pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
651 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
654 /* after flagging the request as done, we
655 * must never even look at it again
657 smp_wmb(); /* make event visible before updating tail */
661 ring = kmap_atomic(ctx->ring_pages[0]);
664 flush_dcache_page(ctx->ring_pages[0]);
666 spin_unlock_irqrestore(&ctx->completion_lock, flags);
668 pr_debug("added to ring %p at [%u]\n", iocb, tail);
671 * Check if the user asked us to deliver the result through an
672 * eventfd. The eventfd_signal() function is safe to be called
675 if (iocb->ki_eventfd != NULL)
676 eventfd_signal(iocb->ki_eventfd, 1);
679 /* everything turned out well, dispose of the aiocb. */
683 * We have to order our ring_info tail store above and test
684 * of the wait list below outside the wait lock. This is
685 * like in wake_up_bit() where clearing a bit has to be
686 * ordered with the unlocked test.
690 if (waitqueue_active(&ctx->wait))
695 EXPORT_SYMBOL(aio_complete);
698 * Pull an event off of the ioctx's event ring. Returns the number of
701 static long aio_read_events_ring(struct kioctx *ctx,
702 struct io_event __user *event, long nr)
704 struct aio_ring *ring;
709 mutex_lock(&ctx->ring_lock);
711 ring = kmap_atomic(ctx->ring_pages[0]);
715 pr_debug("h%u t%u m%u\n", head, ctx->tail, ctx->nr_events);
717 if (head == ctx->tail)
725 avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head;
726 if (head == ctx->tail)
729 avail = min(avail, nr - ret);
730 avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
731 ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
733 pos = head + AIO_EVENTS_OFFSET;
734 page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
735 pos %= AIO_EVENTS_PER_PAGE;
738 copy_ret = copy_to_user(event + ret, ev + pos,
739 sizeof(*ev) * avail);
742 if (unlikely(copy_ret)) {
749 head %= ctx->nr_events;
752 ring = kmap_atomic(ctx->ring_pages[0]);
755 flush_dcache_page(ctx->ring_pages[0]);
757 pr_debug("%li h%u t%u\n", ret, head, ctx->tail);
759 atomic_sub(ret, &ctx->reqs_active);
761 mutex_unlock(&ctx->ring_lock);
766 static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
767 struct io_event __user *event, long *i)
769 long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
774 if (unlikely(atomic_read(&ctx->dead)))
780 return ret < 0 || *i >= min_nr;
783 static long read_events(struct kioctx *ctx, long min_nr, long nr,
784 struct io_event __user *event,
785 struct timespec __user *timeout)
787 ktime_t until = { .tv64 = KTIME_MAX };
793 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
796 until = timespec_to_ktime(ts);
800 * Note that aio_read_events() is being called as the conditional - i.e.
801 * we're calling it after prepare_to_wait() has set task state to
802 * TASK_INTERRUPTIBLE.
804 * But aio_read_events() can block, and if it blocks it's going to flip
805 * the task state back to TASK_RUNNING.
807 * This should be ok, provided it doesn't flip the state back to
808 * TASK_RUNNING and return 0 too much - that causes us to spin. That
809 * will only happen if the mutex_lock() call blocks, and we then find
810 * the ringbuffer empty. So in practice we should be ok, but it's
811 * something to be aware of when touching this code.
813 wait_event_interruptible_hrtimeout(ctx->wait,
814 aio_read_events(ctx, min_nr, nr, event, &ret), until);
816 if (!ret && signal_pending(current))
823 * Create an aio_context capable of receiving at least nr_events.
824 * ctxp must not point to an aio_context that already exists, and
825 * must be initialized to 0 prior to the call. On successful
826 * creation of the aio_context, *ctxp is filled in with the resulting
827 * handle. May fail with -EINVAL if *ctxp is not initialized,
828 * if the specified nr_events exceeds internal limits. May fail
829 * with -EAGAIN if the specified nr_events exceeds the user's limit
830 * of available events. May fail with -ENOMEM if insufficient kernel
831 * resources are available. May fail with -EFAULT if an invalid
832 * pointer is passed for ctxp. Will fail with -ENOSYS if not
835 SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
837 struct kioctx *ioctx = NULL;
841 ret = get_user(ctx, ctxp);
846 if (unlikely(ctx || nr_events == 0)) {
847 pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
852 ioctx = ioctx_alloc(nr_events);
853 ret = PTR_ERR(ioctx);
854 if (!IS_ERR(ioctx)) {
855 ret = put_user(ioctx->user_id, ctxp);
866 * Destroy the aio_context specified. May cancel any outstanding
867 * AIOs and block on completion. Will fail with -ENOSYS if not
868 * implemented. May fail with -EINVAL if the context pointed to
871 SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
873 struct kioctx *ioctx = lookup_ioctx(ctx);
874 if (likely(NULL != ioctx)) {
879 pr_debug("EINVAL: io_destroy: invalid context id\n");
883 static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret)
885 struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg];
889 while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) {
890 ssize_t this = min((ssize_t)iov->iov_len, ret);
891 iov->iov_base += this;
892 iov->iov_len -= this;
893 iocb->ki_left -= this;
895 if (iov->iov_len == 0) {
901 /* the caller should not have done more io than what fit in
902 * the remaining iovecs */
903 BUG_ON(ret > 0 && iocb->ki_left == 0);
906 typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *,
907 unsigned long, loff_t);
909 static ssize_t aio_rw_vect_retry(struct kiocb *iocb, int rw, aio_rw_op *rw_op)
911 struct file *file = iocb->ki_filp;
912 struct address_space *mapping = file->f_mapping;
913 struct inode *inode = mapping->host;
916 /* This matches the pread()/pwrite() logic */
917 if (iocb->ki_pos < 0)
921 file_start_write(file);
923 ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg],
924 iocb->ki_nr_segs - iocb->ki_cur_seg,
927 aio_advance_iovec(iocb, ret);
929 /* retry all partial writes. retry partial reads as long as its a
931 } while (ret > 0 && iocb->ki_left > 0 &&
933 (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))));
935 file_end_write(file);
937 /* This means we must have transferred all that we could */
938 /* No need to retry anymore */
939 if ((ret == 0) || (iocb->ki_left == 0))
940 ret = iocb->ki_nbytes - iocb->ki_left;
942 /* If we managed to write some out we return that, rather than
943 * the eventual error. */
945 && ret < 0 && ret != -EIOCBQUEUED
946 && iocb->ki_nbytes - iocb->ki_left)
947 ret = iocb->ki_nbytes - iocb->ki_left;
952 static ssize_t aio_setup_vectored_rw(int rw, struct kiocb *kiocb, bool compat)
956 kiocb->ki_nr_segs = kiocb->ki_nbytes;
960 ret = compat_rw_copy_check_uvector(rw,
961 (struct compat_iovec __user *)kiocb->ki_buf,
962 kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec,
966 ret = rw_copy_check_uvector(rw,
967 (struct iovec __user *)kiocb->ki_buf,
968 kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec,
973 /* ki_nbytes now reflect bytes instead of segs */
974 kiocb->ki_nbytes = ret;
978 static ssize_t aio_setup_single_vector(int rw, struct kiocb *kiocb)
980 if (unlikely(!access_ok(!rw, kiocb->ki_buf, kiocb->ki_nbytes)))
983 kiocb->ki_iovec = &kiocb->ki_inline_vec;
984 kiocb->ki_iovec->iov_base = kiocb->ki_buf;
985 kiocb->ki_iovec->iov_len = kiocb->ki_nbytes;
986 kiocb->ki_nr_segs = 1;
992 * Performs the initial checks and aio retry method
993 * setup for the kiocb at the time of io submission.
995 static ssize_t aio_run_iocb(struct kiocb *req, bool compat)
997 struct file *file = req->ki_filp;
1003 switch (req->ki_opcode) {
1004 case IOCB_CMD_PREAD:
1005 case IOCB_CMD_PREADV:
1008 rw_op = file->f_op->aio_read;
1011 case IOCB_CMD_PWRITE:
1012 case IOCB_CMD_PWRITEV:
1015 rw_op = file->f_op->aio_write;
1018 if (unlikely(!(file->f_mode & mode)))
1024 ret = (req->ki_opcode == IOCB_CMD_PREADV ||
1025 req->ki_opcode == IOCB_CMD_PWRITEV)
1026 ? aio_setup_vectored_rw(rw, req, compat)
1027 : aio_setup_single_vector(rw, req);
1031 ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
1035 req->ki_nbytes = ret;
1038 ret = aio_rw_vect_retry(req, rw, rw_op);
1041 case IOCB_CMD_FDSYNC:
1042 if (!file->f_op->aio_fsync)
1045 ret = file->f_op->aio_fsync(req, 1);
1048 case IOCB_CMD_FSYNC:
1049 if (!file->f_op->aio_fsync)
1052 ret = file->f_op->aio_fsync(req, 0);
1056 pr_debug("EINVAL: no operation provided\n");
1060 if (ret != -EIOCBQUEUED) {
1062 * There's no easy way to restart the syscall since other AIO's
1063 * may be already running. Just fail this IO with EINTR.
1065 if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
1066 ret == -ERESTARTNOHAND ||
1067 ret == -ERESTART_RESTARTBLOCK))
1069 aio_complete(req, ret, 0);
1075 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1076 struct iocb *iocb, bool compat)
1081 /* enforce forwards compatibility on users */
1082 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
1083 pr_debug("EINVAL: reserve field set\n");
1087 /* prevent overflows */
1089 (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
1090 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
1091 ((ssize_t)iocb->aio_nbytes < 0)
1093 pr_debug("EINVAL: io_submit: overflow check\n");
1097 req = aio_get_req(ctx);
1101 req->ki_filp = fget(iocb->aio_fildes);
1102 if (unlikely(!req->ki_filp)) {
1107 if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1109 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1110 * instance of the file* now. The file descriptor must be
1111 * an eventfd() fd, and will be signaled for each completed
1112 * event using the eventfd_signal() function.
1114 req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
1115 if (IS_ERR(req->ki_eventfd)) {
1116 ret = PTR_ERR(req->ki_eventfd);
1117 req->ki_eventfd = NULL;
1122 ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
1123 if (unlikely(ret)) {
1124 pr_debug("EFAULT: aio_key\n");
1128 req->ki_obj.user = user_iocb;
1129 req->ki_user_data = iocb->aio_data;
1130 req->ki_pos = iocb->aio_offset;
1132 req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf;
1133 req->ki_left = req->ki_nbytes = iocb->aio_nbytes;
1134 req->ki_opcode = iocb->aio_lio_opcode;
1136 ret = aio_run_iocb(req, compat);
1140 aio_put_req(req); /* drop extra ref to req */
1143 atomic_dec(&ctx->reqs_active);
1144 aio_put_req(req); /* drop extra ref to req */
1145 aio_put_req(req); /* drop i/o ref to req */
1149 long do_io_submit(aio_context_t ctx_id, long nr,
1150 struct iocb __user *__user *iocbpp, bool compat)
1155 struct blk_plug plug;
1157 if (unlikely(nr < 0))
1160 if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
1161 nr = LONG_MAX/sizeof(*iocbpp);
1163 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1166 ctx = lookup_ioctx(ctx_id);
1167 if (unlikely(!ctx)) {
1168 pr_debug("EINVAL: invalid context id\n");
1172 blk_start_plug(&plug);
1175 * AKPM: should this return a partial result if some of the IOs were
1176 * successfully submitted?
1178 for (i=0; i<nr; i++) {
1179 struct iocb __user *user_iocb;
1182 if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1187 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1192 ret = io_submit_one(ctx, user_iocb, &tmp, compat);
1196 blk_finish_plug(&plug);
1203 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1204 * the number of iocbs queued. May return -EINVAL if the aio_context
1205 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1206 * *iocbpp[0] is not properly initialized, if the operation specified
1207 * is invalid for the file descriptor in the iocb. May fail with
1208 * -EFAULT if any of the data structures point to invalid data. May
1209 * fail with -EBADF if the file descriptor specified in the first
1210 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1211 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1212 * fail with -ENOSYS if not implemented.
1214 SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
1215 struct iocb __user * __user *, iocbpp)
1217 return do_io_submit(ctx_id, nr, iocbpp, 0);
1221 * Finds a given iocb for cancellation.
1223 static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
1226 struct list_head *pos;
1228 assert_spin_locked(&ctx->ctx_lock);
1230 if (key != KIOCB_KEY)
1233 /* TODO: use a hash or array, this sucks. */
1234 list_for_each(pos, &ctx->active_reqs) {
1235 struct kiocb *kiocb = list_kiocb(pos);
1236 if (kiocb->ki_obj.user == iocb)
1243 * Attempts to cancel an iocb previously passed to io_submit. If
1244 * the operation is successfully cancelled, the resulting event is
1245 * copied into the memory pointed to by result without being placed
1246 * into the completion queue and 0 is returned. May fail with
1247 * -EFAULT if any of the data structures pointed to are invalid.
1248 * May fail with -EINVAL if aio_context specified by ctx_id is
1249 * invalid. May fail with -EAGAIN if the iocb specified was not
1250 * cancelled. Will fail with -ENOSYS if not implemented.
1252 SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
1253 struct io_event __user *, result)
1255 struct io_event res;
1257 struct kiocb *kiocb;
1261 ret = get_user(key, &iocb->aio_key);
1265 ctx = lookup_ioctx(ctx_id);
1269 spin_lock_irq(&ctx->ctx_lock);
1271 kiocb = lookup_kiocb(ctx, iocb, key);
1273 ret = kiocb_cancel(ctx, kiocb, &res);
1277 spin_unlock_irq(&ctx->ctx_lock);
1280 /* Cancellation succeeded -- copy the result
1281 * into the user's buffer.
1283 if (copy_to_user(result, &res, sizeof(res)))
1293 * Attempts to read at least min_nr events and up to nr events from
1294 * the completion queue for the aio_context specified by ctx_id. If
1295 * it succeeds, the number of read events is returned. May fail with
1296 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
1297 * out of range, if timeout is out of range. May fail with -EFAULT
1298 * if any of the memory specified is invalid. May return 0 or
1299 * < min_nr if the timeout specified by timeout has elapsed
1300 * before sufficient events are available, where timeout == NULL
1301 * specifies an infinite timeout. Note that the timeout pointed to by
1302 * timeout is relative. Will fail with -ENOSYS if not implemented.
1304 SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
1307 struct io_event __user *, events,
1308 struct timespec __user *, timeout)
1310 struct kioctx *ioctx = lookup_ioctx(ctx_id);
1313 if (likely(ioctx)) {
1314 if (likely(min_nr <= nr && min_nr >= 0))
1315 ret = read_events(ioctx, min_nr, nr, events, timeout);