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/percpu.h>
30 #include <linux/slab.h>
31 #include <linux/timer.h>
32 #include <linux/aio.h>
33 #include <linux/highmem.h>
34 #include <linux/workqueue.h>
35 #include <linux/security.h>
36 #include <linux/eventfd.h>
37 #include <linux/blkdev.h>
38 #include <linux/compat.h>
39 #include <linux/anon_inodes.h>
40 #include <linux/migrate.h>
41 #include <linux/ramfs.h>
42 #include <linux/percpu-refcount.h>
44 #include <asm/kmap_types.h>
45 #include <asm/uaccess.h>
49 #define AIO_RING_MAGIC 0xa10a10a1
50 #define AIO_RING_COMPAT_FEATURES 1
51 #define AIO_RING_INCOMPAT_FEATURES 0
53 unsigned id; /* kernel internal index number */
54 unsigned nr; /* number of io_events */
59 unsigned compat_features;
60 unsigned incompat_features;
61 unsigned header_length; /* size of aio_ring */
64 struct io_event io_events[0];
65 }; /* 128 bytes + ring size */
67 #define AIO_RING_PAGES 8
72 struct kioctx *table[];
76 unsigned reqs_available;
80 struct percpu_ref users;
83 unsigned long user_id;
85 struct __percpu kioctx_cpu *cpu;
88 * For percpu reqs_available, number of slots we move to/from global
93 * This is what userspace passed to io_setup(), it's not used for
94 * anything but counting against the global max_reqs quota.
96 * The real limit is nr_events - 1, which will be larger (see
101 /* Size of ringbuffer, in units of struct io_event */
104 unsigned long mmap_base;
105 unsigned long mmap_size;
107 struct page **ring_pages;
110 struct rcu_head rcu_head;
111 struct work_struct free_work;
115 * This counts the number of available slots in the ringbuffer,
116 * so we avoid overflowing it: it's decremented (if positive)
117 * when allocating a kiocb and incremented when the resulting
118 * io_event is pulled off the ringbuffer.
120 * We batch accesses to it with a percpu version.
122 atomic_t reqs_available;
123 } ____cacheline_aligned_in_smp;
127 struct list_head active_reqs; /* used for cancellation */
128 } ____cacheline_aligned_in_smp;
131 struct mutex ring_lock;
132 wait_queue_head_t wait;
133 } ____cacheline_aligned_in_smp;
137 spinlock_t completion_lock;
138 } ____cacheline_aligned_in_smp;
140 struct page *internal_pages[AIO_RING_PAGES];
141 struct file *aio_ring_file;
146 /*------ sysctl variables----*/
147 static DEFINE_SPINLOCK(aio_nr_lock);
148 unsigned long aio_nr; /* current system wide number of aio requests */
149 unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
150 /*----end sysctl variables---*/
152 static struct kmem_cache *kiocb_cachep;
153 static struct kmem_cache *kioctx_cachep;
156 * Creates the slab caches used by the aio routines, panic on
157 * failure as this is done early during the boot sequence.
159 static int __init aio_setup(void)
161 kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
162 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
164 pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
168 __initcall(aio_setup);
170 static void aio_free_ring(struct kioctx *ctx)
173 struct file *aio_ring_file = ctx->aio_ring_file;
175 for (i = 0; i < ctx->nr_pages; i++) {
176 pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
177 page_count(ctx->ring_pages[i]));
178 put_page(ctx->ring_pages[i]);
181 if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages)
182 kfree(ctx->ring_pages);
185 truncate_setsize(aio_ring_file->f_inode, 0);
186 pr_debug("pid(%d) i_nlink=%u d_count=%d d_unhashed=%d i_count=%d\n",
187 current->pid, aio_ring_file->f_inode->i_nlink,
188 aio_ring_file->f_path.dentry->d_count,
189 d_unhashed(aio_ring_file->f_path.dentry),
190 atomic_read(&aio_ring_file->f_inode->i_count));
192 ctx->aio_ring_file = NULL;
196 static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
198 vma->vm_ops = &generic_file_vm_ops;
202 static const struct file_operations aio_ring_fops = {
203 .mmap = aio_ring_mmap,
206 static int aio_set_page_dirty(struct page *page)
211 #if IS_ENABLED(CONFIG_MIGRATION)
212 static int aio_migratepage(struct address_space *mapping, struct page *new,
213 struct page *old, enum migrate_mode mode)
215 struct kioctx *ctx = mapping->private_data;
217 unsigned idx = old->index;
220 /* Writeback must be complete */
221 BUG_ON(PageWriteback(old));
224 rc = migrate_page_move_mapping(mapping, new, old, NULL, mode);
225 if (rc != MIGRATEPAGE_SUCCESS) {
232 spin_lock_irqsave(&ctx->completion_lock, flags);
233 migrate_page_copy(new, old);
234 ctx->ring_pages[idx] = new;
235 spin_unlock_irqrestore(&ctx->completion_lock, flags);
241 static const struct address_space_operations aio_ctx_aops = {
242 .set_page_dirty = aio_set_page_dirty,
243 #if IS_ENABLED(CONFIG_MIGRATION)
244 .migratepage = aio_migratepage,
248 static int aio_setup_ring(struct kioctx *ctx)
250 struct aio_ring *ring;
251 unsigned nr_events = ctx->max_reqs;
252 struct mm_struct *mm = current->mm;
253 unsigned long size, populate;
258 /* Compensate for the ring buffer's head/tail overlap entry */
259 nr_events += 2; /* 1 is required, 2 for good luck */
261 size = sizeof(struct aio_ring);
262 size += sizeof(struct io_event) * nr_events;
264 nr_pages = PFN_UP(size);
268 file = anon_inode_getfile_private("[aio]", &aio_ring_fops, ctx, O_RDWR);
270 ctx->aio_ring_file = NULL;
274 file->f_inode->i_mapping->a_ops = &aio_ctx_aops;
275 file->f_inode->i_mapping->private_data = ctx;
276 file->f_inode->i_size = PAGE_SIZE * (loff_t)nr_pages;
278 for (i = 0; i < nr_pages; i++) {
280 page = find_or_create_page(file->f_inode->i_mapping,
281 i, GFP_HIGHUSER | __GFP_ZERO);
284 pr_debug("pid(%d) page[%d]->count=%d\n",
285 current->pid, i, page_count(page));
286 SetPageUptodate(page);
290 ctx->aio_ring_file = file;
291 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
292 / sizeof(struct io_event);
294 ctx->ring_pages = ctx->internal_pages;
295 if (nr_pages > AIO_RING_PAGES) {
296 ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
298 if (!ctx->ring_pages)
302 ctx->mmap_size = nr_pages * PAGE_SIZE;
303 pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
305 down_write(&mm->mmap_sem);
306 ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size,
307 PROT_READ | PROT_WRITE,
308 MAP_SHARED | MAP_POPULATE, 0, &populate);
309 if (IS_ERR((void *)ctx->mmap_base)) {
310 up_write(&mm->mmap_sem);
315 up_write(&mm->mmap_sem);
317 mm_populate(ctx->mmap_base, populate);
319 pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
320 ctx->nr_pages = get_user_pages(current, mm, ctx->mmap_base, nr_pages,
321 1, 0, ctx->ring_pages, NULL);
322 for (i = 0; i < ctx->nr_pages; i++)
323 put_page(ctx->ring_pages[i]);
325 if (unlikely(ctx->nr_pages != nr_pages)) {
330 ctx->user_id = ctx->mmap_base;
331 ctx->nr_events = nr_events; /* trusted copy */
333 ring = kmap_atomic(ctx->ring_pages[0]);
334 ring->nr = nr_events; /* user copy */
336 ring->head = ring->tail = 0;
337 ring->magic = AIO_RING_MAGIC;
338 ring->compat_features = AIO_RING_COMPAT_FEATURES;
339 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
340 ring->header_length = sizeof(struct aio_ring);
342 flush_dcache_page(ctx->ring_pages[0]);
347 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
348 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
349 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
351 void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel)
353 struct kioctx *ctx = req->ki_ctx;
356 spin_lock_irqsave(&ctx->ctx_lock, flags);
358 if (!req->ki_list.next)
359 list_add(&req->ki_list, &ctx->active_reqs);
361 req->ki_cancel = cancel;
363 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
365 EXPORT_SYMBOL(kiocb_set_cancel_fn);
367 static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb)
369 kiocb_cancel_fn *old, *cancel;
372 * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
373 * actually has a cancel function, hence the cmpxchg()
376 cancel = ACCESS_ONCE(kiocb->ki_cancel);
378 if (!cancel || cancel == KIOCB_CANCELLED)
382 cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
383 } while (cancel != old);
385 return cancel(kiocb);
388 static void free_ioctx_rcu(struct rcu_head *head)
390 struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
392 free_percpu(ctx->cpu);
393 kmem_cache_free(kioctx_cachep, ctx);
397 * When this function runs, the kioctx has been removed from the "hash table"
398 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
399 * now it's safe to cancel any that need to be.
401 static void free_ioctx(struct work_struct *work)
403 struct kioctx *ctx = container_of(work, struct kioctx, free_work);
404 struct aio_ring *ring;
409 spin_lock_irq(&ctx->ctx_lock);
411 while (!list_empty(&ctx->active_reqs)) {
412 req = list_first_entry(&ctx->active_reqs,
413 struct kiocb, ki_list);
415 list_del_init(&req->ki_list);
416 kiocb_cancel(ctx, req);
419 spin_unlock_irq(&ctx->ctx_lock);
421 for_each_possible_cpu(cpu) {
422 struct kioctx_cpu *kcpu = per_cpu_ptr(ctx->cpu, cpu);
424 atomic_add(kcpu->reqs_available, &ctx->reqs_available);
425 kcpu->reqs_available = 0;
429 prepare_to_wait(&ctx->wait, &wait, TASK_UNINTERRUPTIBLE);
431 ring = kmap_atomic(ctx->ring_pages[0]);
432 avail = (ring->head <= ring->tail)
433 ? ring->tail - ring->head
434 : ctx->nr_events - ring->head + ring->tail;
436 atomic_add(avail, &ctx->reqs_available);
437 ring->head = ring->tail;
440 if (atomic_read(&ctx->reqs_available) >= ctx->nr_events - 1)
445 finish_wait(&ctx->wait, &wait);
447 WARN_ON(atomic_read(&ctx->reqs_available) > ctx->nr_events - 1);
451 pr_debug("freeing %p\n", ctx);
454 * Here the call_rcu() is between the wait_event() for reqs_active to
455 * hit 0, and freeing the ioctx.
457 * aio_complete() decrements reqs_active, but it has to touch the ioctx
458 * after to issue a wakeup so we use rcu.
460 call_rcu(&ctx->rcu_head, free_ioctx_rcu);
463 static void free_ioctx_ref(struct percpu_ref *ref)
465 struct kioctx *ctx = container_of(ref, struct kioctx, users);
467 INIT_WORK(&ctx->free_work, free_ioctx);
468 schedule_work(&ctx->free_work);
471 static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
474 struct kioctx_table *table, *old;
475 struct aio_ring *ring;
477 spin_lock(&mm->ioctx_lock);
478 table = mm->ioctx_table;
482 for (i = 0; i < table->nr; i++)
483 if (!table->table[i]) {
485 table->table[i] = ctx;
486 spin_unlock(&mm->ioctx_lock);
488 ring = kmap_atomic(ctx->ring_pages[0]);
494 new_nr = (table ? table->nr : 1) * 4;
496 spin_unlock(&mm->ioctx_lock);
498 table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) *
505 spin_lock(&mm->ioctx_lock);
506 old = mm->ioctx_table;
509 rcu_assign_pointer(mm->ioctx_table, table);
510 } else if (table->nr > old->nr) {
511 memcpy(table->table, old->table,
512 old->nr * sizeof(struct kioctx *));
514 rcu_assign_pointer(mm->ioctx_table, table);
524 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
526 static struct kioctx *ioctx_alloc(unsigned nr_events)
528 struct mm_struct *mm = current->mm;
533 * We keep track of the number of available ringbuffer slots, to prevent
534 * overflow (reqs_available), and we also use percpu counters for this.
536 * So since up to half the slots might be on other cpu's percpu counters
537 * and unavailable, double nr_events so userspace sees what they
538 * expected: additionally, we move req_batch slots to/from percpu
539 * counters at a time, so make sure that isn't 0:
541 nr_events = max(nr_events, num_possible_cpus() * 4);
544 /* Prevent overflows */
545 if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
546 (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
547 pr_debug("ENOMEM: nr_events too high\n");
548 return ERR_PTR(-EINVAL);
551 if (!nr_events || (unsigned long)nr_events > (aio_max_nr * 2UL))
552 return ERR_PTR(-EAGAIN);
554 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
556 return ERR_PTR(-ENOMEM);
558 ctx->max_reqs = nr_events;
560 if (percpu_ref_init(&ctx->users, free_ioctx_ref))
563 spin_lock_init(&ctx->ctx_lock);
564 spin_lock_init(&ctx->completion_lock);
565 mutex_init(&ctx->ring_lock);
566 init_waitqueue_head(&ctx->wait);
568 INIT_LIST_HEAD(&ctx->active_reqs);
570 ctx->cpu = alloc_percpu(struct kioctx_cpu);
574 if (aio_setup_ring(ctx) < 0)
577 atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
578 ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
579 if (ctx->req_batch < 1)
582 /* limit the number of system wide aios */
583 spin_lock(&aio_nr_lock);
584 if (aio_nr + nr_events > (aio_max_nr * 2UL) ||
585 aio_nr + nr_events < aio_nr) {
586 spin_unlock(&aio_nr_lock);
589 aio_nr += ctx->max_reqs;
590 spin_unlock(&aio_nr_lock);
592 percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */
594 err = ioctx_add_table(ctx, mm);
596 goto out_cleanup_put;
598 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
599 ctx, ctx->user_id, mm, ctx->nr_events);
603 percpu_ref_put(&ctx->users);
608 free_percpu(ctx->cpu);
610 free_percpu(ctx->users.pcpu_count);
612 if (ctx->aio_ring_file)
613 fput(ctx->aio_ring_file);
614 kmem_cache_free(kioctx_cachep, ctx);
615 pr_debug("error allocating ioctx %d\n", err);
620 * Cancels all outstanding aio requests on an aio context. Used
621 * when the processes owning a context have all exited to encourage
622 * the rapid destruction of the kioctx.
624 static void kill_ioctx(struct mm_struct *mm, struct kioctx *ctx)
626 if (!atomic_xchg(&ctx->dead, 1)) {
627 struct kioctx_table *table;
629 spin_lock(&mm->ioctx_lock);
630 table = mm->ioctx_table;
632 WARN_ON(ctx != table->table[ctx->id]);
633 table->table[ctx->id] = NULL;
634 spin_unlock(&mm->ioctx_lock);
636 /* percpu_ref_kill() will do the necessary call_rcu() */
637 wake_up_all(&ctx->wait);
640 * It'd be more correct to do this in free_ioctx(), after all
641 * the outstanding kiocbs have finished - but by then io_destroy
642 * has already returned, so io_setup() could potentially return
643 * -EAGAIN with no ioctxs actually in use (as far as userspace
646 spin_lock(&aio_nr_lock);
647 BUG_ON(aio_nr - ctx->max_reqs > aio_nr);
648 aio_nr -= ctx->max_reqs;
649 spin_unlock(&aio_nr_lock);
652 vm_munmap(ctx->mmap_base, ctx->mmap_size);
654 percpu_ref_kill(&ctx->users);
658 /* wait_on_sync_kiocb:
659 * Waits on the given sync kiocb to complete.
661 ssize_t wait_on_sync_kiocb(struct kiocb *req)
663 while (!req->ki_ctx) {
664 set_current_state(TASK_UNINTERRUPTIBLE);
669 __set_current_state(TASK_RUNNING);
670 return req->ki_user_data;
672 EXPORT_SYMBOL(wait_on_sync_kiocb);
675 * exit_aio: called when the last user of mm goes away. At this point, there is
676 * no way for any new requests to be submited or any of the io_* syscalls to be
677 * called on the context.
679 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
682 void exit_aio(struct mm_struct *mm)
684 struct kioctx_table *table;
690 table = rcu_dereference(mm->ioctx_table);
693 if (!table || i >= table->nr) {
695 rcu_assign_pointer(mm->ioctx_table, NULL);
701 ctx = table->table[i++];
707 * We don't need to bother with munmap() here -
708 * exit_mmap(mm) is coming and it'll unmap everything.
709 * Since aio_free_ring() uses non-zero ->mmap_size
710 * as indicator that it needs to unmap the area,
711 * just set it to 0; aio_free_ring() is the only
712 * place that uses ->mmap_size, so it's safe.
720 static void put_reqs_available(struct kioctx *ctx, unsigned nr)
722 struct kioctx_cpu *kcpu;
725 kcpu = this_cpu_ptr(ctx->cpu);
727 kcpu->reqs_available += nr;
728 while (kcpu->reqs_available >= ctx->req_batch * 2) {
729 kcpu->reqs_available -= ctx->req_batch;
730 atomic_add(ctx->req_batch, &ctx->reqs_available);
736 static bool get_reqs_available(struct kioctx *ctx)
738 struct kioctx_cpu *kcpu;
742 kcpu = this_cpu_ptr(ctx->cpu);
744 if (!kcpu->reqs_available) {
745 int old, avail = atomic_read(&ctx->reqs_available);
748 if (avail < ctx->req_batch)
752 avail = atomic_cmpxchg(&ctx->reqs_available,
753 avail, avail - ctx->req_batch);
754 } while (avail != old);
756 kcpu->reqs_available += ctx->req_batch;
760 kcpu->reqs_available--;
767 * Allocate a slot for an aio request.
768 * Returns NULL if no requests are free.
770 static inline struct kiocb *aio_get_req(struct kioctx *ctx)
774 if (!get_reqs_available(ctx))
777 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
784 put_reqs_available(ctx, 1);
788 static void kiocb_free(struct kiocb *req)
792 if (req->ki_eventfd != NULL)
793 eventfd_ctx_put(req->ki_eventfd);
794 kmem_cache_free(kiocb_cachep, req);
797 static struct kioctx *lookup_ioctx(unsigned long ctx_id)
799 struct aio_ring __user *ring = (void __user *)ctx_id;
800 struct mm_struct *mm = current->mm;
801 struct kioctx *ctx, *ret = NULL;
802 struct kioctx_table *table;
805 if (get_user(id, &ring->id))
809 table = rcu_dereference(mm->ioctx_table);
811 if (!table || id >= table->nr)
814 ctx = table->table[id];
815 if (ctx && ctx->user_id == ctx_id) {
816 percpu_ref_get(&ctx->users);
825 * Called when the io request on the given iocb is complete.
827 void aio_complete(struct kiocb *iocb, long res, long res2)
829 struct kioctx *ctx = iocb->ki_ctx;
830 struct aio_ring *ring;
831 struct io_event *ev_page, *event;
836 * Special case handling for sync iocbs:
837 * - events go directly into the iocb for fast handling
838 * - the sync task with the iocb in its stack holds the single iocb
839 * ref, no other paths have a way to get another ref
840 * - the sync task helpfully left a reference to itself in the iocb
842 if (is_sync_kiocb(iocb)) {
843 iocb->ki_user_data = res;
845 iocb->ki_ctx = ERR_PTR(-EXDEV);
846 wake_up_process(iocb->ki_obj.tsk);
851 * Take rcu_read_lock() in case the kioctx is being destroyed, as we
852 * need to issue a wakeup after incrementing reqs_available.
856 if (iocb->ki_list.next) {
859 spin_lock_irqsave(&ctx->ctx_lock, flags);
860 list_del(&iocb->ki_list);
861 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
865 * Add a completion event to the ring buffer. Must be done holding
866 * ctx->completion_lock to prevent other code from messing with the tail
867 * pointer since we might be called from irq context.
869 spin_lock_irqsave(&ctx->completion_lock, flags);
872 pos = tail + AIO_EVENTS_OFFSET;
874 if (++tail >= ctx->nr_events)
877 ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
878 event = ev_page + pos % AIO_EVENTS_PER_PAGE;
880 event->obj = (u64)(unsigned long)iocb->ki_obj.user;
881 event->data = iocb->ki_user_data;
885 kunmap_atomic(ev_page);
886 flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
888 pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
889 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
892 /* after flagging the request as done, we
893 * must never even look at it again
895 smp_wmb(); /* make event visible before updating tail */
899 ring = kmap_atomic(ctx->ring_pages[0]);
902 flush_dcache_page(ctx->ring_pages[0]);
904 spin_unlock_irqrestore(&ctx->completion_lock, flags);
906 pr_debug("added to ring %p at [%u]\n", iocb, tail);
909 * Check if the user asked us to deliver the result through an
910 * eventfd. The eventfd_signal() function is safe to be called
913 if (iocb->ki_eventfd != NULL)
914 eventfd_signal(iocb->ki_eventfd, 1);
916 /* everything turned out well, dispose of the aiocb. */
920 * We have to order our ring_info tail store above and test
921 * of the wait list below outside the wait lock. This is
922 * like in wake_up_bit() where clearing a bit has to be
923 * ordered with the unlocked test.
927 if (waitqueue_active(&ctx->wait))
932 EXPORT_SYMBOL(aio_complete);
935 * Pull an event off of the ioctx's event ring. Returns the number of
938 static long aio_read_events_ring(struct kioctx *ctx,
939 struct io_event __user *event, long nr)
941 struct aio_ring *ring;
942 unsigned head, tail, pos;
946 mutex_lock(&ctx->ring_lock);
948 ring = kmap_atomic(ctx->ring_pages[0]);
953 pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
963 avail = (head <= tail ? tail : ctx->nr_events) - head;
967 avail = min(avail, nr - ret);
968 avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
969 ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
971 pos = head + AIO_EVENTS_OFFSET;
972 page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
973 pos %= AIO_EVENTS_PER_PAGE;
976 copy_ret = copy_to_user(event + ret, ev + pos,
977 sizeof(*ev) * avail);
980 if (unlikely(copy_ret)) {
987 head %= ctx->nr_events;
990 ring = kmap_atomic(ctx->ring_pages[0]);
993 flush_dcache_page(ctx->ring_pages[0]);
995 pr_debug("%li h%u t%u\n", ret, head, tail);
997 put_reqs_available(ctx, ret);
999 mutex_unlock(&ctx->ring_lock);
1004 static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
1005 struct io_event __user *event, long *i)
1007 long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
1012 if (unlikely(atomic_read(&ctx->dead)))
1018 return ret < 0 || *i >= min_nr;
1021 static long read_events(struct kioctx *ctx, long min_nr, long nr,
1022 struct io_event __user *event,
1023 struct timespec __user *timeout)
1025 ktime_t until = { .tv64 = KTIME_MAX };
1031 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
1034 until = timespec_to_ktime(ts);
1038 * Note that aio_read_events() is being called as the conditional - i.e.
1039 * we're calling it after prepare_to_wait() has set task state to
1040 * TASK_INTERRUPTIBLE.
1042 * But aio_read_events() can block, and if it blocks it's going to flip
1043 * the task state back to TASK_RUNNING.
1045 * This should be ok, provided it doesn't flip the state back to
1046 * TASK_RUNNING and return 0 too much - that causes us to spin. That
1047 * will only happen if the mutex_lock() call blocks, and we then find
1048 * the ringbuffer empty. So in practice we should be ok, but it's
1049 * something to be aware of when touching this code.
1051 wait_event_interruptible_hrtimeout(ctx->wait,
1052 aio_read_events(ctx, min_nr, nr, event, &ret), until);
1054 if (!ret && signal_pending(current))
1061 * Create an aio_context capable of receiving at least nr_events.
1062 * ctxp must not point to an aio_context that already exists, and
1063 * must be initialized to 0 prior to the call. On successful
1064 * creation of the aio_context, *ctxp is filled in with the resulting
1065 * handle. May fail with -EINVAL if *ctxp is not initialized,
1066 * if the specified nr_events exceeds internal limits. May fail
1067 * with -EAGAIN if the specified nr_events exceeds the user's limit
1068 * of available events. May fail with -ENOMEM if insufficient kernel
1069 * resources are available. May fail with -EFAULT if an invalid
1070 * pointer is passed for ctxp. Will fail with -ENOSYS if not
1073 SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1075 struct kioctx *ioctx = NULL;
1079 ret = get_user(ctx, ctxp);
1084 if (unlikely(ctx || nr_events == 0)) {
1085 pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
1090 ioctx = ioctx_alloc(nr_events);
1091 ret = PTR_ERR(ioctx);
1092 if (!IS_ERR(ioctx)) {
1093 ret = put_user(ioctx->user_id, ctxp);
1095 kill_ioctx(current->mm, ioctx);
1096 percpu_ref_put(&ioctx->users);
1104 * Destroy the aio_context specified. May cancel any outstanding
1105 * AIOs and block on completion. Will fail with -ENOSYS if not
1106 * implemented. May fail with -EINVAL if the context pointed to
1109 SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1111 struct kioctx *ioctx = lookup_ioctx(ctx);
1112 if (likely(NULL != ioctx)) {
1113 kill_ioctx(current->mm, ioctx);
1114 percpu_ref_put(&ioctx->users);
1117 pr_debug("EINVAL: io_destroy: invalid context id\n");
1121 typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *,
1122 unsigned long, loff_t);
1124 static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb,
1125 int rw, char __user *buf,
1126 unsigned long *nr_segs,
1127 struct iovec **iovec,
1132 *nr_segs = kiocb->ki_nbytes;
1134 #ifdef CONFIG_COMPAT
1136 ret = compat_rw_copy_check_uvector(rw,
1137 (struct compat_iovec __user *)buf,
1138 *nr_segs, 1, *iovec, iovec);
1141 ret = rw_copy_check_uvector(rw,
1142 (struct iovec __user *)buf,
1143 *nr_segs, 1, *iovec, iovec);
1147 /* ki_nbytes now reflect bytes instead of segs */
1148 kiocb->ki_nbytes = ret;
1152 static ssize_t aio_setup_single_vector(struct kiocb *kiocb,
1153 int rw, char __user *buf,
1154 unsigned long *nr_segs,
1155 struct iovec *iovec)
1157 if (unlikely(!access_ok(!rw, buf, kiocb->ki_nbytes)))
1160 iovec->iov_base = buf;
1161 iovec->iov_len = kiocb->ki_nbytes;
1168 * Performs the initial checks and aio retry method
1169 * setup for the kiocb at the time of io submission.
1171 static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
1172 char __user *buf, bool compat)
1174 struct file *file = req->ki_filp;
1176 unsigned long nr_segs;
1180 struct iovec inline_vec, *iovec = &inline_vec;
1183 case IOCB_CMD_PREAD:
1184 case IOCB_CMD_PREADV:
1187 rw_op = file->f_op->aio_read;
1190 case IOCB_CMD_PWRITE:
1191 case IOCB_CMD_PWRITEV:
1194 rw_op = file->f_op->aio_write;
1197 if (unlikely(!(file->f_mode & mode)))
1203 ret = (opcode == IOCB_CMD_PREADV ||
1204 opcode == IOCB_CMD_PWRITEV)
1205 ? aio_setup_vectored_rw(req, rw, buf, &nr_segs,
1207 : aio_setup_single_vector(req, rw, buf, &nr_segs,
1212 ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
1214 if (iovec != &inline_vec)
1219 req->ki_nbytes = ret;
1221 /* XXX: move/kill - rw_verify_area()? */
1222 /* This matches the pread()/pwrite() logic */
1223 if (req->ki_pos < 0) {
1229 file_start_write(file);
1231 ret = rw_op(req, iovec, nr_segs, req->ki_pos);
1234 file_end_write(file);
1237 case IOCB_CMD_FDSYNC:
1238 if (!file->f_op->aio_fsync)
1241 ret = file->f_op->aio_fsync(req, 1);
1244 case IOCB_CMD_FSYNC:
1245 if (!file->f_op->aio_fsync)
1248 ret = file->f_op->aio_fsync(req, 0);
1252 pr_debug("EINVAL: no operation provided\n");
1256 if (iovec != &inline_vec)
1259 if (ret != -EIOCBQUEUED) {
1261 * There's no easy way to restart the syscall since other AIO's
1262 * may be already running. Just fail this IO with EINTR.
1264 if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
1265 ret == -ERESTARTNOHAND ||
1266 ret == -ERESTART_RESTARTBLOCK))
1268 aio_complete(req, ret, 0);
1274 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1275 struct iocb *iocb, bool compat)
1280 /* enforce forwards compatibility on users */
1281 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
1282 pr_debug("EINVAL: reserve field set\n");
1286 /* prevent overflows */
1288 (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
1289 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
1290 ((ssize_t)iocb->aio_nbytes < 0)
1292 pr_debug("EINVAL: io_submit: overflow check\n");
1296 req = aio_get_req(ctx);
1300 req->ki_filp = fget(iocb->aio_fildes);
1301 if (unlikely(!req->ki_filp)) {
1306 if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1308 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1309 * instance of the file* now. The file descriptor must be
1310 * an eventfd() fd, and will be signaled for each completed
1311 * event using the eventfd_signal() function.
1313 req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
1314 if (IS_ERR(req->ki_eventfd)) {
1315 ret = PTR_ERR(req->ki_eventfd);
1316 req->ki_eventfd = NULL;
1321 ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
1322 if (unlikely(ret)) {
1323 pr_debug("EFAULT: aio_key\n");
1327 req->ki_obj.user = user_iocb;
1328 req->ki_user_data = iocb->aio_data;
1329 req->ki_pos = iocb->aio_offset;
1330 req->ki_nbytes = iocb->aio_nbytes;
1332 ret = aio_run_iocb(req, iocb->aio_lio_opcode,
1333 (char __user *)(unsigned long)iocb->aio_buf,
1340 put_reqs_available(ctx, 1);
1345 long do_io_submit(aio_context_t ctx_id, long nr,
1346 struct iocb __user *__user *iocbpp, bool compat)
1351 struct blk_plug plug;
1353 if (unlikely(nr < 0))
1356 if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
1357 nr = LONG_MAX/sizeof(*iocbpp);
1359 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1362 ctx = lookup_ioctx(ctx_id);
1363 if (unlikely(!ctx)) {
1364 pr_debug("EINVAL: invalid context id\n");
1368 blk_start_plug(&plug);
1371 * AKPM: should this return a partial result if some of the IOs were
1372 * successfully submitted?
1374 for (i=0; i<nr; i++) {
1375 struct iocb __user *user_iocb;
1378 if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1383 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1388 ret = io_submit_one(ctx, user_iocb, &tmp, compat);
1392 blk_finish_plug(&plug);
1394 percpu_ref_put(&ctx->users);
1399 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1400 * the number of iocbs queued. May return -EINVAL if the aio_context
1401 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1402 * *iocbpp[0] is not properly initialized, if the operation specified
1403 * is invalid for the file descriptor in the iocb. May fail with
1404 * -EFAULT if any of the data structures point to invalid data. May
1405 * fail with -EBADF if the file descriptor specified in the first
1406 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1407 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1408 * fail with -ENOSYS if not implemented.
1410 SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
1411 struct iocb __user * __user *, iocbpp)
1413 return do_io_submit(ctx_id, nr, iocbpp, 0);
1417 * Finds a given iocb for cancellation.
1419 static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
1422 struct list_head *pos;
1424 assert_spin_locked(&ctx->ctx_lock);
1426 if (key != KIOCB_KEY)
1429 /* TODO: use a hash or array, this sucks. */
1430 list_for_each(pos, &ctx->active_reqs) {
1431 struct kiocb *kiocb = list_kiocb(pos);
1432 if (kiocb->ki_obj.user == iocb)
1439 * Attempts to cancel an iocb previously passed to io_submit. If
1440 * the operation is successfully cancelled, the resulting event is
1441 * copied into the memory pointed to by result without being placed
1442 * into the completion queue and 0 is returned. May fail with
1443 * -EFAULT if any of the data structures pointed to are invalid.
1444 * May fail with -EINVAL if aio_context specified by ctx_id is
1445 * invalid. May fail with -EAGAIN if the iocb specified was not
1446 * cancelled. Will fail with -ENOSYS if not implemented.
1448 SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
1449 struct io_event __user *, result)
1452 struct kiocb *kiocb;
1456 ret = get_user(key, &iocb->aio_key);
1460 ctx = lookup_ioctx(ctx_id);
1464 spin_lock_irq(&ctx->ctx_lock);
1466 kiocb = lookup_kiocb(ctx, iocb, key);
1468 ret = kiocb_cancel(ctx, kiocb);
1472 spin_unlock_irq(&ctx->ctx_lock);
1476 * The result argument is no longer used - the io_event is
1477 * always delivered via the ring buffer. -EINPROGRESS indicates
1478 * cancellation is progress:
1483 percpu_ref_put(&ctx->users);
1489 * Attempts to read at least min_nr events and up to nr events from
1490 * the completion queue for the aio_context specified by ctx_id. If
1491 * it succeeds, the number of read events is returned. May fail with
1492 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
1493 * out of range, if timeout is out of range. May fail with -EFAULT
1494 * if any of the memory specified is invalid. May return 0 or
1495 * < min_nr if the timeout specified by timeout has elapsed
1496 * before sufficient events are available, where timeout == NULL
1497 * specifies an infinite timeout. Note that the timeout pointed to by
1498 * timeout is relative. Will fail with -ENOSYS if not implemented.
1500 SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
1503 struct io_event __user *, events,
1504 struct timespec __user *, timeout)
1506 struct kioctx *ioctx = lookup_ioctx(ctx_id);
1509 if (likely(ioctx)) {
1510 if (likely(min_nr <= nr && min_nr >= 0))
1511 ret = read_events(ioctx, min_nr, nr, events, timeout);
1512 percpu_ref_put(&ioctx->users);