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>
43 #include <asm/kmap_types.h>
44 #include <asm/uaccess.h>
48 #define AIO_RING_MAGIC 0xa10a10a1
49 #define AIO_RING_COMPAT_FEATURES 1
50 #define AIO_RING_INCOMPAT_FEATURES 0
52 unsigned id; /* kernel internal index number */
53 unsigned nr; /* number of io_events */
58 unsigned compat_features;
59 unsigned incompat_features;
60 unsigned header_length; /* size of aio_ring */
63 struct io_event io_events[0];
64 }; /* 128 bytes + ring size */
66 #define AIO_RING_PAGES 8
69 unsigned reqs_available;
76 /* This needs improving */
77 unsigned long user_id;
78 struct hlist_node list;
80 struct __percpu kioctx_cpu *cpu;
83 * For percpu reqs_available, number of slots we move to/from global
88 * This is what userspace passed to io_setup(), it's not used for
89 * anything but counting against the global max_reqs quota.
91 * The real limit is nr_events - 1, which will be larger (see
96 /* Size of ringbuffer, in units of struct io_event */
99 unsigned long mmap_base;
100 unsigned long mmap_size;
102 struct page **ring_pages;
105 struct rcu_head rcu_head;
106 struct work_struct rcu_work;
110 * This counts the number of available slots in the ringbuffer,
111 * so we avoid overflowing it: it's decremented (if positive)
112 * when allocating a kiocb and incremented when the resulting
113 * io_event is pulled off the ringbuffer.
115 * We batch accesses to it with a percpu version.
117 atomic_t reqs_available;
118 } ____cacheline_aligned_in_smp;
122 struct list_head active_reqs; /* used for cancellation */
123 } ____cacheline_aligned_in_smp;
126 struct mutex ring_lock;
127 wait_queue_head_t wait;
128 } ____cacheline_aligned_in_smp;
132 spinlock_t completion_lock;
133 } ____cacheline_aligned_in_smp;
135 struct page *internal_pages[AIO_RING_PAGES];
136 struct file *aio_ring_file;
139 /*------ sysctl variables----*/
140 static DEFINE_SPINLOCK(aio_nr_lock);
141 unsigned long aio_nr; /* current system wide number of aio requests */
142 unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
143 /*----end sysctl variables---*/
145 static struct kmem_cache *kiocb_cachep;
146 static struct kmem_cache *kioctx_cachep;
149 * Creates the slab caches used by the aio routines, panic on
150 * failure as this is done early during the boot sequence.
152 static int __init aio_setup(void)
154 kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
155 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
157 pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
161 __initcall(aio_setup);
163 static void aio_free_ring(struct kioctx *ctx)
166 struct file *aio_ring_file = ctx->aio_ring_file;
168 for (i = 0; i < ctx->nr_pages; i++) {
169 pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
170 page_count(ctx->ring_pages[i]));
171 put_page(ctx->ring_pages[i]);
174 if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages)
175 kfree(ctx->ring_pages);
178 truncate_setsize(aio_ring_file->f_inode, 0);
179 pr_debug("pid(%d) i_nlink=%u d_count=%d d_unhashed=%d i_count=%d\n",
180 current->pid, aio_ring_file->f_inode->i_nlink,
181 aio_ring_file->f_path.dentry->d_count,
182 d_unhashed(aio_ring_file->f_path.dentry),
183 atomic_read(&aio_ring_file->f_inode->i_count));
185 ctx->aio_ring_file = NULL;
189 static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
191 vma->vm_ops = &generic_file_vm_ops;
195 static const struct file_operations aio_ring_fops = {
196 .mmap = aio_ring_mmap,
199 static int aio_set_page_dirty(struct page *page)
204 #if IS_ENABLED(CONFIG_MIGRATION)
205 static int aio_migratepage(struct address_space *mapping, struct page *new,
206 struct page *old, enum migrate_mode mode)
208 struct kioctx *ctx = mapping->private_data;
210 unsigned idx = old->index;
213 /* Writeback must be complete */
214 BUG_ON(PageWriteback(old));
217 rc = migrate_page_move_mapping(mapping, new, old, NULL, mode);
218 if (rc != MIGRATEPAGE_SUCCESS) {
225 spin_lock_irqsave(&ctx->completion_lock, flags);
226 migrate_page_copy(new, old);
227 ctx->ring_pages[idx] = new;
228 spin_unlock_irqrestore(&ctx->completion_lock, flags);
234 static const struct address_space_operations aio_ctx_aops = {
235 .set_page_dirty = aio_set_page_dirty,
236 #if IS_ENABLED(CONFIG_MIGRATION)
237 .migratepage = aio_migratepage,
241 static int aio_setup_ring(struct kioctx *ctx)
243 struct aio_ring *ring;
244 unsigned nr_events = ctx->max_reqs;
245 struct mm_struct *mm = current->mm;
246 unsigned long size, populate;
251 /* Compensate for the ring buffer's head/tail overlap entry */
252 nr_events += 2; /* 1 is required, 2 for good luck */
254 size = sizeof(struct aio_ring);
255 size += sizeof(struct io_event) * nr_events;
257 nr_pages = PFN_UP(size);
261 file = anon_inode_getfile_private("[aio]", &aio_ring_fops, ctx, O_RDWR);
263 ctx->aio_ring_file = NULL;
267 file->f_inode->i_mapping->a_ops = &aio_ctx_aops;
268 file->f_inode->i_mapping->private_data = ctx;
269 file->f_inode->i_size = PAGE_SIZE * (loff_t)nr_pages;
271 for (i = 0; i < nr_pages; i++) {
273 page = find_or_create_page(file->f_inode->i_mapping,
274 i, GFP_HIGHUSER | __GFP_ZERO);
277 pr_debug("pid(%d) page[%d]->count=%d\n",
278 current->pid, i, page_count(page));
279 SetPageUptodate(page);
283 ctx->aio_ring_file = file;
284 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
285 / sizeof(struct io_event);
287 ctx->ring_pages = ctx->internal_pages;
288 if (nr_pages > AIO_RING_PAGES) {
289 ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
291 if (!ctx->ring_pages)
295 ctx->mmap_size = nr_pages * PAGE_SIZE;
296 pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
298 down_write(&mm->mmap_sem);
299 ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size,
300 PROT_READ | PROT_WRITE,
301 MAP_SHARED | MAP_POPULATE, 0, &populate);
302 if (IS_ERR((void *)ctx->mmap_base)) {
303 up_write(&mm->mmap_sem);
308 up_write(&mm->mmap_sem);
310 mm_populate(ctx->mmap_base, populate);
312 pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
313 ctx->nr_pages = get_user_pages(current, mm, ctx->mmap_base, nr_pages,
314 1, 0, ctx->ring_pages, NULL);
315 for (i = 0; i < ctx->nr_pages; i++)
316 put_page(ctx->ring_pages[i]);
318 if (unlikely(ctx->nr_pages != nr_pages)) {
323 ctx->user_id = ctx->mmap_base;
324 ctx->nr_events = nr_events; /* trusted copy */
326 ring = kmap_atomic(ctx->ring_pages[0]);
327 ring->nr = nr_events; /* user copy */
328 ring->id = ctx->user_id;
329 ring->head = ring->tail = 0;
330 ring->magic = AIO_RING_MAGIC;
331 ring->compat_features = AIO_RING_COMPAT_FEATURES;
332 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
333 ring->header_length = sizeof(struct aio_ring);
335 flush_dcache_page(ctx->ring_pages[0]);
340 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
341 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
342 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
344 void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel)
346 struct kioctx *ctx = req->ki_ctx;
349 spin_lock_irqsave(&ctx->ctx_lock, flags);
351 if (!req->ki_list.next)
352 list_add(&req->ki_list, &ctx->active_reqs);
354 req->ki_cancel = cancel;
356 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
358 EXPORT_SYMBOL(kiocb_set_cancel_fn);
360 static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb,
361 struct io_event *res)
363 kiocb_cancel_fn *old, *cancel;
367 * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
368 * actually has a cancel function, hence the cmpxchg()
371 cancel = ACCESS_ONCE(kiocb->ki_cancel);
373 if (!cancel || cancel == KIOCB_CANCELLED)
377 cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
378 } while (cancel != old);
380 atomic_inc(&kiocb->ki_users);
381 spin_unlock_irq(&ctx->ctx_lock);
383 memset(res, 0, sizeof(*res));
384 res->obj = (u64)(unsigned long)kiocb->ki_obj.user;
385 res->data = kiocb->ki_user_data;
386 ret = cancel(kiocb, res);
388 spin_lock_irq(&ctx->ctx_lock);
393 static void free_ioctx_rcu(struct rcu_head *head)
395 struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
397 free_percpu(ctx->cpu);
398 kmem_cache_free(kioctx_cachep, ctx);
402 * When this function runs, the kioctx has been removed from the "hash table"
403 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
404 * now it's safe to cancel any that need to be.
406 static void free_ioctx(struct kioctx *ctx)
408 struct aio_ring *ring;
411 unsigned cpu, head, avail;
413 spin_lock_irq(&ctx->ctx_lock);
415 while (!list_empty(&ctx->active_reqs)) {
416 req = list_first_entry(&ctx->active_reqs,
417 struct kiocb, ki_list);
419 list_del_init(&req->ki_list);
420 kiocb_cancel(ctx, req, &res);
423 spin_unlock_irq(&ctx->ctx_lock);
425 for_each_possible_cpu(cpu) {
426 struct kioctx_cpu *kcpu = per_cpu_ptr(ctx->cpu, cpu);
428 atomic_add(kcpu->reqs_available, &ctx->reqs_available);
429 kcpu->reqs_available = 0;
432 ring = kmap_atomic(ctx->ring_pages[0]);
436 while (atomic_read(&ctx->reqs_available) < ctx->nr_events - 1) {
437 wait_event(ctx->wait,
438 (head != ctx->tail) ||
439 (atomic_read(&ctx->reqs_available) >=
440 ctx->nr_events - 1));
442 avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head;
444 atomic_add(avail, &ctx->reqs_available);
446 head %= ctx->nr_events;
449 WARN_ON(atomic_read(&ctx->reqs_available) > ctx->nr_events - 1);
453 pr_debug("freeing %p\n", ctx);
456 * Here the call_rcu() is between the wait_event() for reqs_active to
457 * hit 0, and freeing the ioctx.
459 * aio_complete() decrements reqs_active, but it has to touch the ioctx
460 * after to issue a wakeup so we use rcu.
462 call_rcu(&ctx->rcu_head, free_ioctx_rcu);
465 static void put_ioctx(struct kioctx *ctx)
467 if (unlikely(atomic_dec_and_test(&ctx->users)))
472 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
474 static struct kioctx *ioctx_alloc(unsigned nr_events)
476 struct mm_struct *mm = current->mm;
481 * We keep track of the number of available ringbuffer slots, to prevent
482 * overflow (reqs_available), and we also use percpu counters for this.
484 * So since up to half the slots might be on other cpu's percpu counters
485 * and unavailable, double nr_events so userspace sees what they
486 * expected: additionally, we move req_batch slots to/from percpu
487 * counters at a time, so make sure that isn't 0:
489 nr_events = max(nr_events, num_possible_cpus() * 4);
492 /* Prevent overflows */
493 if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
494 (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
495 pr_debug("ENOMEM: nr_events too high\n");
496 return ERR_PTR(-EINVAL);
499 if (!nr_events || (unsigned long)nr_events > aio_max_nr)
500 return ERR_PTR(-EAGAIN);
502 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
504 return ERR_PTR(-ENOMEM);
506 ctx->max_reqs = nr_events;
508 atomic_set(&ctx->users, 2);
509 atomic_set(&ctx->dead, 0);
510 spin_lock_init(&ctx->ctx_lock);
511 spin_lock_init(&ctx->completion_lock);
512 mutex_init(&ctx->ring_lock);
513 init_waitqueue_head(&ctx->wait);
515 INIT_LIST_HEAD(&ctx->active_reqs);
517 ctx->cpu = alloc_percpu(struct kioctx_cpu);
521 if (aio_setup_ring(ctx) < 0)
524 atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
525 ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
526 BUG_ON(!ctx->req_batch);
528 /* limit the number of system wide aios */
529 spin_lock(&aio_nr_lock);
530 if (aio_nr + nr_events > aio_max_nr ||
531 aio_nr + nr_events < aio_nr) {
532 spin_unlock(&aio_nr_lock);
535 aio_nr += ctx->max_reqs;
536 spin_unlock(&aio_nr_lock);
538 /* now link into global list. */
539 spin_lock(&mm->ioctx_lock);
540 hlist_add_head_rcu(&ctx->list, &mm->ioctx_list);
541 spin_unlock(&mm->ioctx_lock);
543 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
544 ctx, ctx->user_id, mm, ctx->nr_events);
551 free_percpu(ctx->cpu);
553 if (ctx->aio_ring_file)
554 fput(ctx->aio_ring_file);
555 kmem_cache_free(kioctx_cachep, ctx);
556 pr_debug("error allocating ioctx %d\n", err);
560 static void kill_ioctx_work(struct work_struct *work)
562 struct kioctx *ctx = container_of(work, struct kioctx, rcu_work);
564 wake_up_all(&ctx->wait);
568 static void kill_ioctx_rcu(struct rcu_head *head)
570 struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
572 INIT_WORK(&ctx->rcu_work, kill_ioctx_work);
573 schedule_work(&ctx->rcu_work);
577 * Cancels all outstanding aio requests on an aio context. Used
578 * when the processes owning a context have all exited to encourage
579 * the rapid destruction of the kioctx.
581 static void kill_ioctx(struct kioctx *ctx)
583 if (!atomic_xchg(&ctx->dead, 1)) {
584 hlist_del_rcu(&ctx->list);
587 * It'd be more correct to do this in free_ioctx(), after all
588 * the outstanding kiocbs have finished - but by then io_destroy
589 * has already returned, so io_setup() could potentially return
590 * -EAGAIN with no ioctxs actually in use (as far as userspace
593 spin_lock(&aio_nr_lock);
594 BUG_ON(aio_nr - ctx->max_reqs > aio_nr);
595 aio_nr -= ctx->max_reqs;
596 spin_unlock(&aio_nr_lock);
599 vm_munmap(ctx->mmap_base, ctx->mmap_size);
601 /* Between hlist_del_rcu() and dropping the initial ref */
602 call_rcu(&ctx->rcu_head, kill_ioctx_rcu);
606 /* wait_on_sync_kiocb:
607 * Waits on the given sync kiocb to complete.
609 ssize_t wait_on_sync_kiocb(struct kiocb *iocb)
611 while (atomic_read(&iocb->ki_users)) {
612 set_current_state(TASK_UNINTERRUPTIBLE);
613 if (!atomic_read(&iocb->ki_users))
617 __set_current_state(TASK_RUNNING);
618 return iocb->ki_user_data;
620 EXPORT_SYMBOL(wait_on_sync_kiocb);
623 * exit_aio: called when the last user of mm goes away. At this point, there is
624 * no way for any new requests to be submited or any of the io_* syscalls to be
625 * called on the context.
627 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
630 void exit_aio(struct mm_struct *mm)
633 struct hlist_node *n;
635 hlist_for_each_entry_safe(ctx, n, &mm->ioctx_list, list) {
636 if (1 != atomic_read(&ctx->users))
638 "exit_aio:ioctx still alive: %d %d %d\n",
639 atomic_read(&ctx->users),
640 atomic_read(&ctx->dead),
641 atomic_read(&ctx->reqs_available));
643 * We don't need to bother with munmap() here -
644 * exit_mmap(mm) is coming and it'll unmap everything.
645 * Since aio_free_ring() uses non-zero ->mmap_size
646 * as indicator that it needs to unmap the area,
647 * just set it to 0; aio_free_ring() is the only
648 * place that uses ->mmap_size, so it's safe.
656 static void put_reqs_available(struct kioctx *ctx, unsigned nr)
658 struct kioctx_cpu *kcpu;
661 kcpu = this_cpu_ptr(ctx->cpu);
663 kcpu->reqs_available += nr;
664 while (kcpu->reqs_available >= ctx->req_batch * 2) {
665 kcpu->reqs_available -= ctx->req_batch;
666 atomic_add(ctx->req_batch, &ctx->reqs_available);
672 static bool get_reqs_available(struct kioctx *ctx)
674 struct kioctx_cpu *kcpu;
678 kcpu = this_cpu_ptr(ctx->cpu);
680 if (!kcpu->reqs_available) {
681 int old, avail = atomic_read(&ctx->reqs_available);
684 if (avail < ctx->req_batch)
688 avail = atomic_cmpxchg(&ctx->reqs_available,
689 avail, avail - ctx->req_batch);
690 } while (avail != old);
692 kcpu->reqs_available += ctx->req_batch;
696 kcpu->reqs_available--;
703 * Allocate a slot for an aio request. Increments the ki_users count
704 * of the kioctx so that the kioctx stays around until all requests are
705 * complete. Returns NULL if no requests are free.
707 * Returns with kiocb->ki_users set to 2. The io submit code path holds
708 * an extra reference while submitting the i/o.
709 * This prevents races between the aio code path referencing the
710 * req (after submitting it) and aio_complete() freeing the req.
712 static inline struct kiocb *aio_get_req(struct kioctx *ctx)
716 if (!get_reqs_available(ctx))
719 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
723 atomic_set(&req->ki_users, 2);
727 put_reqs_available(ctx, 1);
731 static void kiocb_free(struct kiocb *req)
735 if (req->ki_eventfd != NULL)
736 eventfd_ctx_put(req->ki_eventfd);
739 if (req->ki_iovec != &req->ki_inline_vec)
740 kfree(req->ki_iovec);
741 kmem_cache_free(kiocb_cachep, req);
744 void aio_put_req(struct kiocb *req)
746 if (atomic_dec_and_test(&req->ki_users))
749 EXPORT_SYMBOL(aio_put_req);
751 static struct kioctx *lookup_ioctx(unsigned long ctx_id)
753 struct mm_struct *mm = current->mm;
754 struct kioctx *ctx, *ret = NULL;
758 hlist_for_each_entry_rcu(ctx, &mm->ioctx_list, list) {
759 if (ctx->user_id == ctx_id) {
760 atomic_inc(&ctx->users);
771 * Called when the io request on the given iocb is complete.
773 void aio_complete(struct kiocb *iocb, long res, long res2)
775 struct kioctx *ctx = iocb->ki_ctx;
776 struct aio_ring *ring;
777 struct io_event *ev_page, *event;
782 * Special case handling for sync iocbs:
783 * - events go directly into the iocb for fast handling
784 * - the sync task with the iocb in its stack holds the single iocb
785 * ref, no other paths have a way to get another ref
786 * - the sync task helpfully left a reference to itself in the iocb
788 if (is_sync_kiocb(iocb)) {
789 BUG_ON(atomic_read(&iocb->ki_users) != 1);
790 iocb->ki_user_data = res;
791 atomic_set(&iocb->ki_users, 0);
792 wake_up_process(iocb->ki_obj.tsk);
797 * Take rcu_read_lock() in case the kioctx is being destroyed, as we
798 * need to issue a wakeup after incrementing reqs_available.
802 if (iocb->ki_list.next) {
805 spin_lock_irqsave(&ctx->ctx_lock, flags);
806 list_del(&iocb->ki_list);
807 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
811 * cancelled requests don't get events, userland was given one
812 * when the event got cancelled.
814 if (unlikely(xchg(&iocb->ki_cancel,
815 KIOCB_CANCELLED) == KIOCB_CANCELLED)) {
817 * Can't use the percpu reqs_available here - could race with
820 atomic_inc(&ctx->reqs_available);
821 /* Still need the wake_up in case free_ioctx is waiting */
826 * Add a completion event to the ring buffer. Must be done holding
827 * ctx->completion_lock to prevent other code from messing with the tail
828 * pointer since we might be called from irq context.
830 spin_lock_irqsave(&ctx->completion_lock, flags);
833 pos = tail + AIO_EVENTS_OFFSET;
835 if (++tail >= ctx->nr_events)
838 ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
839 event = ev_page + pos % AIO_EVENTS_PER_PAGE;
841 event->obj = (u64)(unsigned long)iocb->ki_obj.user;
842 event->data = iocb->ki_user_data;
846 kunmap_atomic(ev_page);
847 flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
849 pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
850 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
853 /* after flagging the request as done, we
854 * must never even look at it again
856 smp_wmb(); /* make event visible before updating tail */
860 ring = kmap_atomic(ctx->ring_pages[0]);
863 flush_dcache_page(ctx->ring_pages[0]);
865 spin_unlock_irqrestore(&ctx->completion_lock, flags);
867 pr_debug("added to ring %p at [%u]\n", iocb, tail);
870 * Check if the user asked us to deliver the result through an
871 * eventfd. The eventfd_signal() function is safe to be called
874 if (iocb->ki_eventfd != NULL)
875 eventfd_signal(iocb->ki_eventfd, 1);
878 /* everything turned out well, dispose of the aiocb. */
882 * We have to order our ring_info tail store above and test
883 * of the wait list below outside the wait lock. This is
884 * like in wake_up_bit() where clearing a bit has to be
885 * ordered with the unlocked test.
889 if (waitqueue_active(&ctx->wait))
894 EXPORT_SYMBOL(aio_complete);
897 * Pull an event off of the ioctx's event ring. Returns the number of
900 static long aio_read_events_ring(struct kioctx *ctx,
901 struct io_event __user *event, long nr)
903 struct aio_ring *ring;
908 mutex_lock(&ctx->ring_lock);
910 ring = kmap_atomic(ctx->ring_pages[0]);
914 pr_debug("h%u t%u m%u\n", head, ctx->tail, ctx->nr_events);
916 if (head == ctx->tail)
924 avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head;
925 if (head == ctx->tail)
928 avail = min(avail, nr - ret);
929 avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
930 ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
932 pos = head + AIO_EVENTS_OFFSET;
933 page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
934 pos %= AIO_EVENTS_PER_PAGE;
937 copy_ret = copy_to_user(event + ret, ev + pos,
938 sizeof(*ev) * avail);
941 if (unlikely(copy_ret)) {
948 head %= ctx->nr_events;
951 ring = kmap_atomic(ctx->ring_pages[0]);
954 flush_dcache_page(ctx->ring_pages[0]);
956 pr_debug("%li h%u t%u\n", ret, head, ctx->tail);
958 put_reqs_available(ctx, ret);
960 mutex_unlock(&ctx->ring_lock);
965 static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
966 struct io_event __user *event, long *i)
968 long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
973 if (unlikely(atomic_read(&ctx->dead)))
979 return ret < 0 || *i >= min_nr;
982 static long read_events(struct kioctx *ctx, long min_nr, long nr,
983 struct io_event __user *event,
984 struct timespec __user *timeout)
986 ktime_t until = { .tv64 = KTIME_MAX };
992 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
995 until = timespec_to_ktime(ts);
999 * Note that aio_read_events() is being called as the conditional - i.e.
1000 * we're calling it after prepare_to_wait() has set task state to
1001 * TASK_INTERRUPTIBLE.
1003 * But aio_read_events() can block, and if it blocks it's going to flip
1004 * the task state back to TASK_RUNNING.
1006 * This should be ok, provided it doesn't flip the state back to
1007 * TASK_RUNNING and return 0 too much - that causes us to spin. That
1008 * will only happen if the mutex_lock() call blocks, and we then find
1009 * the ringbuffer empty. So in practice we should be ok, but it's
1010 * something to be aware of when touching this code.
1012 wait_event_interruptible_hrtimeout(ctx->wait,
1013 aio_read_events(ctx, min_nr, nr, event, &ret), until);
1015 if (!ret && signal_pending(current))
1022 * Create an aio_context capable of receiving at least nr_events.
1023 * ctxp must not point to an aio_context that already exists, and
1024 * must be initialized to 0 prior to the call. On successful
1025 * creation of the aio_context, *ctxp is filled in with the resulting
1026 * handle. May fail with -EINVAL if *ctxp is not initialized,
1027 * if the specified nr_events exceeds internal limits. May fail
1028 * with -EAGAIN if the specified nr_events exceeds the user's limit
1029 * of available events. May fail with -ENOMEM if insufficient kernel
1030 * resources are available. May fail with -EFAULT if an invalid
1031 * pointer is passed for ctxp. Will fail with -ENOSYS if not
1034 SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1036 struct kioctx *ioctx = NULL;
1040 ret = get_user(ctx, ctxp);
1045 if (unlikely(ctx || nr_events == 0)) {
1046 pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
1051 ioctx = ioctx_alloc(nr_events);
1052 ret = PTR_ERR(ioctx);
1053 if (!IS_ERR(ioctx)) {
1054 ret = put_user(ioctx->user_id, ctxp);
1065 * Destroy the aio_context specified. May cancel any outstanding
1066 * AIOs and block on completion. Will fail with -ENOSYS if not
1067 * implemented. May fail with -EINVAL if the context pointed to
1070 SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1072 struct kioctx *ioctx = lookup_ioctx(ctx);
1073 if (likely(NULL != ioctx)) {
1078 pr_debug("EINVAL: io_destroy: invalid context id\n");
1082 static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret)
1084 struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg];
1088 while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) {
1089 ssize_t this = min((ssize_t)iov->iov_len, ret);
1090 iov->iov_base += this;
1091 iov->iov_len -= this;
1092 iocb->ki_left -= this;
1094 if (iov->iov_len == 0) {
1100 /* the caller should not have done more io than what fit in
1101 * the remaining iovecs */
1102 BUG_ON(ret > 0 && iocb->ki_left == 0);
1105 typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *,
1106 unsigned long, loff_t);
1108 static ssize_t aio_rw_vect_retry(struct kiocb *iocb, int rw, aio_rw_op *rw_op)
1110 struct file *file = iocb->ki_filp;
1111 struct address_space *mapping = file->f_mapping;
1112 struct inode *inode = mapping->host;
1115 /* This matches the pread()/pwrite() logic */
1116 if (iocb->ki_pos < 0)
1120 file_start_write(file);
1122 ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg],
1123 iocb->ki_nr_segs - iocb->ki_cur_seg,
1126 aio_advance_iovec(iocb, ret);
1128 /* retry all partial writes. retry partial reads as long as its a
1130 } while (ret > 0 && iocb->ki_left > 0 &&
1132 (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))));
1134 file_end_write(file);
1136 /* This means we must have transferred all that we could */
1137 /* No need to retry anymore */
1138 if ((ret == 0) || (iocb->ki_left == 0))
1139 ret = iocb->ki_nbytes - iocb->ki_left;
1141 /* If we managed to write some out we return that, rather than
1142 * the eventual error. */
1144 && ret < 0 && ret != -EIOCBQUEUED
1145 && iocb->ki_nbytes - iocb->ki_left)
1146 ret = iocb->ki_nbytes - iocb->ki_left;
1151 static ssize_t aio_setup_vectored_rw(int rw, struct kiocb *kiocb, bool compat)
1155 kiocb->ki_nr_segs = kiocb->ki_nbytes;
1157 #ifdef CONFIG_COMPAT
1159 ret = compat_rw_copy_check_uvector(rw,
1160 (struct compat_iovec __user *)kiocb->ki_buf,
1161 kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec,
1165 ret = rw_copy_check_uvector(rw,
1166 (struct iovec __user *)kiocb->ki_buf,
1167 kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec,
1172 /* ki_nbytes now reflect bytes instead of segs */
1173 kiocb->ki_nbytes = ret;
1177 static ssize_t aio_setup_single_vector(int rw, struct kiocb *kiocb)
1179 if (unlikely(!access_ok(!rw, kiocb->ki_buf, kiocb->ki_nbytes)))
1182 kiocb->ki_iovec = &kiocb->ki_inline_vec;
1183 kiocb->ki_iovec->iov_base = kiocb->ki_buf;
1184 kiocb->ki_iovec->iov_len = kiocb->ki_nbytes;
1185 kiocb->ki_nr_segs = 1;
1191 * Performs the initial checks and aio retry method
1192 * setup for the kiocb at the time of io submission.
1194 static ssize_t aio_run_iocb(struct kiocb *req, bool compat)
1196 struct file *file = req->ki_filp;
1202 switch (req->ki_opcode) {
1203 case IOCB_CMD_PREAD:
1204 case IOCB_CMD_PREADV:
1207 rw_op = file->f_op->aio_read;
1210 case IOCB_CMD_PWRITE:
1211 case IOCB_CMD_PWRITEV:
1214 rw_op = file->f_op->aio_write;
1217 if (unlikely(!(file->f_mode & mode)))
1223 ret = (req->ki_opcode == IOCB_CMD_PREADV ||
1224 req->ki_opcode == IOCB_CMD_PWRITEV)
1225 ? aio_setup_vectored_rw(rw, req, compat)
1226 : aio_setup_single_vector(rw, req);
1230 ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
1234 req->ki_nbytes = ret;
1237 ret = aio_rw_vect_retry(req, rw, rw_op);
1240 case IOCB_CMD_FDSYNC:
1241 if (!file->f_op->aio_fsync)
1244 ret = file->f_op->aio_fsync(req, 1);
1247 case IOCB_CMD_FSYNC:
1248 if (!file->f_op->aio_fsync)
1251 ret = file->f_op->aio_fsync(req, 0);
1255 pr_debug("EINVAL: no operation provided\n");
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;
1331 req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf;
1332 req->ki_left = req->ki_nbytes = iocb->aio_nbytes;
1333 req->ki_opcode = iocb->aio_lio_opcode;
1335 ret = aio_run_iocb(req, compat);
1339 aio_put_req(req); /* drop extra ref to req */
1342 put_reqs_available(ctx, 1);
1343 aio_put_req(req); /* drop extra ref to req */
1344 aio_put_req(req); /* drop i/o ref to req */
1348 long do_io_submit(aio_context_t ctx_id, long nr,
1349 struct iocb __user *__user *iocbpp, bool compat)
1354 struct blk_plug plug;
1356 if (unlikely(nr < 0))
1359 if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
1360 nr = LONG_MAX/sizeof(*iocbpp);
1362 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1365 ctx = lookup_ioctx(ctx_id);
1366 if (unlikely(!ctx)) {
1367 pr_debug("EINVAL: invalid context id\n");
1371 blk_start_plug(&plug);
1374 * AKPM: should this return a partial result if some of the IOs were
1375 * successfully submitted?
1377 for (i=0; i<nr; i++) {
1378 struct iocb __user *user_iocb;
1381 if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1386 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1391 ret = io_submit_one(ctx, user_iocb, &tmp, compat);
1395 blk_finish_plug(&plug);
1402 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1403 * the number of iocbs queued. May return -EINVAL if the aio_context
1404 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1405 * *iocbpp[0] is not properly initialized, if the operation specified
1406 * is invalid for the file descriptor in the iocb. May fail with
1407 * -EFAULT if any of the data structures point to invalid data. May
1408 * fail with -EBADF if the file descriptor specified in the first
1409 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1410 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1411 * fail with -ENOSYS if not implemented.
1413 SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
1414 struct iocb __user * __user *, iocbpp)
1416 return do_io_submit(ctx_id, nr, iocbpp, 0);
1420 * Finds a given iocb for cancellation.
1422 static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
1425 struct list_head *pos;
1427 assert_spin_locked(&ctx->ctx_lock);
1429 if (key != KIOCB_KEY)
1432 /* TODO: use a hash or array, this sucks. */
1433 list_for_each(pos, &ctx->active_reqs) {
1434 struct kiocb *kiocb = list_kiocb(pos);
1435 if (kiocb->ki_obj.user == iocb)
1442 * Attempts to cancel an iocb previously passed to io_submit. If
1443 * the operation is successfully cancelled, the resulting event is
1444 * copied into the memory pointed to by result without being placed
1445 * into the completion queue and 0 is returned. May fail with
1446 * -EFAULT if any of the data structures pointed to are invalid.
1447 * May fail with -EINVAL if aio_context specified by ctx_id is
1448 * invalid. May fail with -EAGAIN if the iocb specified was not
1449 * cancelled. Will fail with -ENOSYS if not implemented.
1451 SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
1452 struct io_event __user *, result)
1454 struct io_event res;
1456 struct kiocb *kiocb;
1460 ret = get_user(key, &iocb->aio_key);
1464 ctx = lookup_ioctx(ctx_id);
1468 spin_lock_irq(&ctx->ctx_lock);
1470 kiocb = lookup_kiocb(ctx, iocb, key);
1472 ret = kiocb_cancel(ctx, kiocb, &res);
1476 spin_unlock_irq(&ctx->ctx_lock);
1479 /* Cancellation succeeded -- copy the result
1480 * into the user's buffer.
1482 if (copy_to_user(result, &res, sizeof(res)))
1492 * Attempts to read at least min_nr events and up to nr events from
1493 * the completion queue for the aio_context specified by ctx_id. If
1494 * it succeeds, the number of read events is returned. May fail with
1495 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
1496 * out of range, if timeout is out of range. May fail with -EFAULT
1497 * if any of the memory specified is invalid. May return 0 or
1498 * < min_nr if the timeout specified by timeout has elapsed
1499 * before sufficient events are available, where timeout == NULL
1500 * specifies an infinite timeout. Note that the timeout pointed to by
1501 * timeout is relative. Will fail with -ENOSYS if not implemented.
1503 SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
1506 struct io_event __user *, events,
1507 struct timespec __user *, timeout)
1509 struct kioctx *ioctx = lookup_ioctx(ctx_id);
1512 if (likely(ioctx)) {
1513 if (likely(min_nr <= nr && min_nr >= 0))
1514 ret = read_events(ioctx, min_nr, nr, events, timeout);