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/percpu-refcount.h>
41 #include <asm/kmap_types.h>
42 #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
65 unsigned reqs_available;
69 struct percpu_ref users;
71 /* This needs improving */
72 unsigned long user_id;
73 struct hlist_node list;
75 struct __percpu kioctx_cpu *cpu;
81 /* sys_io_setup currently limits this to an unsigned int */
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;
94 atomic_t reqs_available;
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 unsigned shadow_tail;
106 } ____cacheline_aligned_in_smp;
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]);
147 vm_munmap(ctx->mmap_base, ctx->mmap_size);
149 if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages)
150 kfree(ctx->ring_pages);
153 static int aio_setup_ring(struct kioctx *ctx)
155 struct aio_ring *ring;
156 unsigned nr_events = ctx->max_reqs;
157 struct mm_struct *mm = current->mm;
158 unsigned long size, populate;
161 nr_events = max(nr_events, num_possible_cpus() * 4);
164 /* Compensate for the ring buffer's head/tail overlap entry */
165 nr_events += 2; /* 1 is required, 2 for good luck */
167 size = sizeof(struct aio_ring);
168 size += sizeof(struct io_event) * nr_events;
169 nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT;
174 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event);
177 ctx->ring_pages = ctx->internal_pages;
178 if (nr_pages > AIO_RING_PAGES) {
179 ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
181 if (!ctx->ring_pages)
185 ctx->mmap_size = nr_pages * PAGE_SIZE;
186 pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
187 down_write(&mm->mmap_sem);
188 ctx->mmap_base = do_mmap_pgoff(NULL, 0, ctx->mmap_size,
189 PROT_READ|PROT_WRITE,
190 MAP_ANONYMOUS|MAP_PRIVATE, 0, &populate);
191 if (IS_ERR((void *)ctx->mmap_base)) {
192 up_write(&mm->mmap_sem);
198 pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
199 ctx->nr_pages = get_user_pages(current, mm, ctx->mmap_base, nr_pages,
200 1, 0, ctx->ring_pages, NULL);
201 up_write(&mm->mmap_sem);
203 if (unlikely(ctx->nr_pages != nr_pages)) {
208 mm_populate(ctx->mmap_base, populate);
210 ctx->user_id = ctx->mmap_base;
211 ctx->nr = nr_events; /* trusted copy */
213 ring = kmap_atomic(ctx->ring_pages[0]);
214 ring->nr = nr_events; /* user copy */
215 ring->id = ctx->user_id;
216 ring->head = ring->tail = 0;
217 ring->magic = AIO_RING_MAGIC;
218 ring->compat_features = AIO_RING_COMPAT_FEATURES;
219 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
220 ring->header_length = sizeof(struct aio_ring);
222 flush_dcache_page(ctx->ring_pages[0]);
227 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
228 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
229 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
231 void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel)
233 struct kioctx *ctx = req->ki_ctx;
236 spin_lock_irqsave(&ctx->ctx_lock, flags);
238 if (!req->ki_list.next)
239 list_add(&req->ki_list, &ctx->active_reqs);
241 req->ki_cancel = cancel;
243 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
245 EXPORT_SYMBOL(kiocb_set_cancel_fn);
247 static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb,
248 struct io_event *res)
250 kiocb_cancel_fn *old, *cancel;
254 * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
255 * actually has a cancel function, hence the cmpxchg()
258 cancel = ACCESS_ONCE(kiocb->ki_cancel);
260 if (!cancel || cancel == KIOCB_CANCELLED)
264 cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
265 } while (cancel != old);
267 atomic_inc(&kiocb->ki_users);
268 spin_unlock_irq(&ctx->ctx_lock);
270 memset(res, 0, sizeof(*res));
271 res->obj = (u64)(unsigned long)kiocb->ki_obj.user;
272 res->data = kiocb->ki_user_data;
273 ret = cancel(kiocb, res);
275 spin_lock_irq(&ctx->ctx_lock);
280 static void free_ioctx_rcu(struct rcu_head *head)
282 struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
284 free_percpu(ctx->cpu);
285 kmem_cache_free(kioctx_cachep, ctx);
289 * When this function runs, the kioctx has been removed from the "hash table"
290 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
291 * now it's safe to cancel any that need to be.
293 static void free_ioctx(struct kioctx *ctx)
295 struct aio_ring *ring;
298 unsigned cpu, head, avail;
300 spin_lock_irq(&ctx->ctx_lock);
302 while (!list_empty(&ctx->active_reqs)) {
303 req = list_first_entry(&ctx->active_reqs,
304 struct kiocb, ki_list);
306 list_del_init(&req->ki_list);
307 kiocb_cancel(ctx, req, &res);
310 spin_unlock_irq(&ctx->ctx_lock);
312 for_each_possible_cpu(cpu) {
313 struct kioctx_cpu *kcpu = per_cpu_ptr(ctx->cpu, cpu);
315 atomic_add(kcpu->reqs_available, &ctx->reqs_available);
316 kcpu->reqs_available = 0;
319 ring = kmap_atomic(ctx->ring_pages[0]);
323 while (atomic_read(&ctx->reqs_available) < ctx->nr) {
324 wait_event(ctx->wait, head != ctx->shadow_tail);
326 avail = (head < ctx->shadow_tail ? ctx->shadow_tail : ctx->nr) - head;
328 atomic_add(avail, &ctx->reqs_available);
333 WARN_ON(atomic_read(&ctx->reqs_available) > ctx->nr);
337 spin_lock(&aio_nr_lock);
338 BUG_ON(aio_nr - ctx->max_reqs > aio_nr);
339 aio_nr -= ctx->max_reqs;
340 spin_unlock(&aio_nr_lock);
342 pr_debug("freeing %p\n", ctx);
345 * Here the call_rcu() is between the wait_event() for reqs_active to
346 * hit 0, and freeing the ioctx.
348 * aio_complete() decrements reqs_active, but it has to touch the ioctx
349 * after to issue a wakeup so we use rcu.
351 call_rcu(&ctx->rcu_head, free_ioctx_rcu);
354 static void put_ioctx(struct kioctx *ctx)
356 if (percpu_ref_put(&ctx->users))
361 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
363 static struct kioctx *ioctx_alloc(unsigned nr_events)
365 struct mm_struct *mm = current->mm;
369 /* Prevent overflows */
370 if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
371 (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
372 pr_debug("ENOMEM: nr_events too high\n");
373 return ERR_PTR(-EINVAL);
376 if (!nr_events || (unsigned long)nr_events > aio_max_nr)
377 return ERR_PTR(-EAGAIN);
379 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
381 return ERR_PTR(-ENOMEM);
383 ctx->max_reqs = nr_events;
385 percpu_ref_init(&ctx->users);
387 percpu_ref_get(&ctx->users);
390 spin_lock_init(&ctx->ctx_lock);
391 mutex_init(&ctx->ring_lock);
392 init_waitqueue_head(&ctx->wait);
394 INIT_LIST_HEAD(&ctx->active_reqs);
396 ctx->cpu = alloc_percpu(struct kioctx_cpu);
400 if (aio_setup_ring(ctx) < 0)
403 atomic_set(&ctx->reqs_available, ctx->nr);
404 ctx->req_batch = ctx->nr / (num_possible_cpus() * 4);
405 BUG_ON(!ctx->req_batch);
407 /* limit the number of system wide aios */
408 spin_lock(&aio_nr_lock);
409 if (aio_nr + nr_events > aio_max_nr ||
410 aio_nr + nr_events < aio_nr) {
411 spin_unlock(&aio_nr_lock);
414 aio_nr += ctx->max_reqs;
415 spin_unlock(&aio_nr_lock);
417 /* now link into global list. */
418 spin_lock(&mm->ioctx_lock);
419 hlist_add_head_rcu(&ctx->list, &mm->ioctx_list);
420 spin_unlock(&mm->ioctx_lock);
422 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
423 ctx, ctx->user_id, mm, ctx->nr);
430 free_percpu(ctx->cpu);
432 kmem_cache_free(kioctx_cachep, ctx);
433 pr_debug("error allocating ioctx %d\n", err);
437 static void kill_ioctx_work(struct work_struct *work)
439 struct kioctx *ctx = container_of(work, struct kioctx, rcu_work);
441 wake_up_all(&ctx->wait);
445 static void kill_ioctx_rcu(struct rcu_head *head)
447 struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
449 INIT_WORK(&ctx->rcu_work, kill_ioctx_work);
450 schedule_work(&ctx->rcu_work);
454 * Cancels all outstanding aio requests on an aio context. Used
455 * when the processes owning a context have all exited to encourage
456 * the rapid destruction of the kioctx.
458 static void kill_ioctx(struct kioctx *ctx)
460 if (percpu_ref_kill(&ctx->users)) {
461 hlist_del_rcu(&ctx->list);
462 /* Between hlist_del_rcu() and dropping the initial ref */
466 * We can't punt to workqueue here because put_ioctx() ->
467 * free_ioctx() will unmap the ringbuffer, and that has to be
468 * done in the original process's context. kill_ioctx_rcu/work()
469 * exist for exit_aio(), as in that path free_ioctx() won't do
472 kill_ioctx_work(&ctx->rcu_work);
476 /* wait_on_sync_kiocb:
477 * Waits on the given sync kiocb to complete.
479 ssize_t wait_on_sync_kiocb(struct kiocb *iocb)
481 while (atomic_read(&iocb->ki_users)) {
482 set_current_state(TASK_UNINTERRUPTIBLE);
483 if (!atomic_read(&iocb->ki_users))
487 __set_current_state(TASK_RUNNING);
488 return iocb->ki_user_data;
490 EXPORT_SYMBOL(wait_on_sync_kiocb);
493 * exit_aio: called when the last user of mm goes away. At this point, there is
494 * no way for any new requests to be submited or any of the io_* syscalls to be
495 * called on the context.
497 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
500 void exit_aio(struct mm_struct *mm)
503 struct hlist_node *n;
505 hlist_for_each_entry_safe(ctx, n, &mm->ioctx_list, list) {
507 * We don't need to bother with munmap() here -
508 * exit_mmap(mm) is coming and it'll unmap everything.
509 * Since aio_free_ring() uses non-zero ->mmap_size
510 * as indicator that it needs to unmap the area,
511 * just set it to 0; aio_free_ring() is the only
512 * place that uses ->mmap_size, so it's safe.
516 if (percpu_ref_kill(&ctx->users)) {
517 hlist_del_rcu(&ctx->list);
518 call_rcu(&ctx->rcu_head, kill_ioctx_rcu);
523 static void put_reqs_available(struct kioctx *ctx, unsigned nr)
525 struct kioctx_cpu *kcpu;
528 kcpu = this_cpu_ptr(ctx->cpu);
530 kcpu->reqs_available += nr;
531 while (kcpu->reqs_available >= ctx->req_batch * 2) {
532 kcpu->reqs_available -= ctx->req_batch;
533 atomic_add(ctx->req_batch, &ctx->reqs_available);
539 static bool get_reqs_available(struct kioctx *ctx)
541 struct kioctx_cpu *kcpu;
545 kcpu = this_cpu_ptr(ctx->cpu);
547 if (!kcpu->reqs_available) {
548 int old, avail = atomic_read(&ctx->reqs_available);
551 if (avail < ctx->req_batch)
555 avail = atomic_cmpxchg(&ctx->reqs_available,
556 avail, avail - ctx->req_batch);
557 } while (avail != old);
559 kcpu->reqs_available += ctx->req_batch;
563 kcpu->reqs_available--;
570 * Allocate a slot for an aio request. Increments the ki_users count
571 * of the kioctx so that the kioctx stays around until all requests are
572 * complete. Returns NULL if no requests are free.
574 * Returns with kiocb->ki_users set to 2. The io submit code path holds
575 * an extra reference while submitting the i/o.
576 * This prevents races between the aio code path referencing the
577 * req (after submitting it) and aio_complete() freeing the req.
579 static inline struct kiocb *aio_get_req(struct kioctx *ctx)
583 if (!get_reqs_available(ctx))
586 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
590 atomic_set(&req->ki_users, 2);
594 put_reqs_available(ctx, 1);
598 static void kiocb_free(struct kiocb *req)
602 if (req->ki_eventfd != NULL)
603 eventfd_ctx_put(req->ki_eventfd);
606 if (req->ki_iovec != &req->ki_inline_vec)
607 kfree(req->ki_iovec);
608 kmem_cache_free(kiocb_cachep, req);
611 void aio_put_req(struct kiocb *req)
613 if (atomic_dec_and_test(&req->ki_users))
616 EXPORT_SYMBOL(aio_put_req);
618 static struct kioctx *lookup_ioctx(unsigned long ctx_id)
620 struct mm_struct *mm = current->mm;
621 struct kioctx *ctx, *ret = NULL;
625 hlist_for_each_entry_rcu(ctx, &mm->ioctx_list, list) {
626 if (ctx->user_id == ctx_id){
627 percpu_ref_get(&ctx->users);
637 static inline unsigned kioctx_ring_put(struct kioctx *ctx, struct kiocb *req,
640 struct io_event *ev_page, *event;
641 unsigned pos = tail + AIO_EVENTS_OFFSET;
643 if (++tail >= ctx->nr)
646 ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
647 event = ev_page + pos % AIO_EVENTS_PER_PAGE;
649 event->obj = (u64)(unsigned long)req->ki_obj.user;
650 event->data = req->ki_user_data;
651 event->res = req->ki_res;
652 event->res2 = req->ki_res2;
654 kunmap_atomic(ev_page);
655 flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
657 pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
658 ctx, tail, req, req->ki_obj.user, req->ki_user_data,
659 req->ki_res, req->ki_res2);
664 static inline unsigned kioctx_ring_lock(struct kioctx *ctx)
669 * ctx->tail is both our lock and the canonical version of the tail
672 while ((tail = xchg(&ctx->tail, UINT_MAX)) == UINT_MAX)
678 static inline void kioctx_ring_unlock(struct kioctx *ctx, unsigned tail)
680 struct aio_ring *ring;
683 /* make event visible before updating tail */
685 ctx->shadow_tail = tail;
687 ring = kmap_atomic(ctx->ring_pages[0]);
690 flush_dcache_page(ctx->ring_pages[0]);
692 /* unlock, make new tail visible before checking waitlist */
697 if (waitqueue_active(&ctx->wait))
701 void batch_complete_aio(struct batch_complete *batch)
703 struct kioctx *ctx = NULL;
704 struct eventfd_ctx *eventfd = NULL;
709 if (RB_EMPTY_ROOT(&batch->kiocb))
713 * Take rcu_read_lock() in case the kioctx is being destroyed, as we
714 * need to issue a wakeup after incrementing reqs_available.
717 local_irq_save(flags);
719 n = rb_first(&batch->kiocb);
721 struct kiocb *req = container_of(n, struct kiocb, ki_node);
724 n->rb_right->__rb_parent_color = n->__rb_parent_color;
733 if (unlikely(xchg(&req->ki_cancel,
734 KIOCB_CANCELLED) == KIOCB_CANCELLED)) {
736 * Can't use the percpu reqs_available here - could race
739 atomic_inc(&req->ki_ctx->reqs_available);
744 if (unlikely(req->ki_eventfd != eventfd)) {
746 /* Make event visible */
747 kioctx_ring_unlock(ctx, tail);
750 eventfd_signal(eventfd, 1);
751 eventfd_ctx_put(eventfd);
754 eventfd = req->ki_eventfd;
755 req->ki_eventfd = NULL;
758 if (unlikely(req->ki_ctx != ctx)) {
760 kioctx_ring_unlock(ctx, tail);
763 tail = kioctx_ring_lock(ctx);
766 tail = kioctx_ring_put(ctx, req, tail);
770 kioctx_ring_unlock(ctx, tail);
771 local_irq_restore(flags);
775 * Check if the user asked us to deliver the result through an
776 * eventfd. The eventfd_signal() function is safe to be called
780 eventfd_signal(eventfd, 1);
781 eventfd_ctx_put(eventfd);
784 EXPORT_SYMBOL(batch_complete_aio);
786 /* aio_complete_batch
787 * Called when the io request on the given iocb is complete; @batch may be
790 void aio_complete_batch(struct kiocb *req, long res, long res2,
791 struct batch_complete *batch)
796 if (req->ki_list.next) {
797 struct kioctx *ctx = req->ki_ctx;
800 spin_lock_irqsave(&ctx->ctx_lock, flags);
801 list_del(&req->ki_list);
802 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
806 * Special case handling for sync iocbs:
807 * - events go directly into the iocb for fast handling
808 * - the sync task with the iocb in its stack holds the single iocb
809 * ref, no other paths have a way to get another ref
810 * - the sync task helpfully left a reference to itself in the iocb
812 if (is_sync_kiocb(req)) {
813 BUG_ON(atomic_read(&req->ki_users) != 1);
814 req->ki_user_data = req->ki_res;
815 atomic_set(&req->ki_users, 0);
816 wake_up_process(req->ki_obj.tsk);
820 struct rb_node **n = &batch->kiocb.rb_node, *parent = NULL;
824 t = container_of(*n, struct kiocb, ki_node);
826 res = req->ki_ctx != t->ki_ctx
827 ? req->ki_ctx < t->ki_ctx
828 : req->ki_eventfd != t->ki_eventfd
829 ? req->ki_eventfd < t->ki_eventfd
832 n = res ? &(*n)->rb_left : &(*n)->rb_right;
835 rb_link_node(&req->ki_node, parent, n);
836 rb_insert_color(&req->ki_node, &batch->kiocb);
838 struct batch_complete batch_stack;
840 memset(&req->ki_node, 0, sizeof(req->ki_node));
841 batch_stack.kiocb.rb_node = &req->ki_node;
843 batch_complete_aio(&batch_stack);
846 EXPORT_SYMBOL(aio_complete_batch);
849 * Pull an event off of the ioctx's event ring. Returns the number of
852 static int aio_read_events_ring(struct kioctx *ctx,
853 struct io_event __user *event, long nr)
855 struct aio_ring *ring;
857 int ret = 0, copy_ret;
859 if (!mutex_trylock(&ctx->ring_lock)) {
860 __set_current_state(TASK_RUNNING);
861 mutex_lock(&ctx->ring_lock);
864 ring = kmap_atomic(ctx->ring_pages[0]);
868 pr_debug("h%u t%u m%u\n", head, ctx->shadow_tail, ctx->nr);
870 if (head == ctx->shadow_tail)
873 __set_current_state(TASK_RUNNING);
876 unsigned i = (head < ctx->shadow_tail ? ctx->shadow_tail : ctx->nr) - head;
880 if (head == ctx->shadow_tail)
883 i = min_t(int, i, nr - ret);
884 i = min_t(int, i, AIO_EVENTS_PER_PAGE -
885 ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
887 pos = head + AIO_EVENTS_OFFSET;
888 page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
889 pos %= AIO_EVENTS_PER_PAGE;
892 copy_ret = copy_to_user(event + ret, ev + pos, sizeof(*ev) * i);
895 if (unlikely(copy_ret)) {
905 ring = kmap_atomic(ctx->ring_pages[0]);
908 flush_dcache_page(ctx->ring_pages[0]);
910 pr_debug("%d h%u t%u\n", ret, head, ctx->shadow_tail);
912 put_reqs_available(ctx, ret);
914 mutex_unlock(&ctx->ring_lock);
919 static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
920 struct io_event __user *event, long *i)
922 long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
927 if (unlikely(percpu_ref_dead(&ctx->users)))
933 return ret < 0 || *i >= min_nr;
936 static long read_events(struct kioctx *ctx, long min_nr, long nr,
937 struct io_event __user *event,
938 struct timespec __user *timeout)
940 ktime_t until = { .tv64 = KTIME_MAX };
946 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
949 until = timespec_to_ktime(ts);
952 wait_event_interruptible_hrtimeout(ctx->wait,
953 aio_read_events(ctx, min_nr, nr, event, &ret), until);
955 if (!ret && signal_pending(current))
962 * Create an aio_context capable of receiving at least nr_events.
963 * ctxp must not point to an aio_context that already exists, and
964 * must be initialized to 0 prior to the call. On successful
965 * creation of the aio_context, *ctxp is filled in with the resulting
966 * handle. May fail with -EINVAL if *ctxp is not initialized,
967 * if the specified nr_events exceeds internal limits. May fail
968 * with -EAGAIN if the specified nr_events exceeds the user's limit
969 * of available events. May fail with -ENOMEM if insufficient kernel
970 * resources are available. May fail with -EFAULT if an invalid
971 * pointer is passed for ctxp. Will fail with -ENOSYS if not
974 SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
976 struct kioctx *ioctx = NULL;
980 ret = get_user(ctx, ctxp);
985 if (unlikely(ctx || nr_events == 0)) {
986 pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
991 ioctx = ioctx_alloc(nr_events);
992 ret = PTR_ERR(ioctx);
993 if (!IS_ERR(ioctx)) {
994 ret = put_user(ioctx->user_id, ctxp);
1005 * Destroy the aio_context specified. May cancel any outstanding
1006 * AIOs and block on completion. Will fail with -ENOSYS if not
1007 * implemented. May fail with -EINVAL if the context pointed to
1010 SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1012 struct kioctx *ioctx = lookup_ioctx(ctx);
1013 if (likely(NULL != ioctx)) {
1018 pr_debug("EINVAL: io_destroy: invalid context id\n");
1022 static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret)
1024 struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg];
1028 while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) {
1029 ssize_t this = min((ssize_t)iov->iov_len, ret);
1030 iov->iov_base += this;
1031 iov->iov_len -= this;
1032 iocb->ki_left -= this;
1034 if (iov->iov_len == 0) {
1040 /* the caller should not have done more io than what fit in
1041 * the remaining iovecs */
1042 BUG_ON(ret > 0 && iocb->ki_left == 0);
1045 typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *,
1046 unsigned long, loff_t);
1048 static ssize_t aio_rw_vect_retry(struct kiocb *iocb, int rw, aio_rw_op *rw_op)
1050 struct file *file = iocb->ki_filp;
1051 struct address_space *mapping = file->f_mapping;
1052 struct inode *inode = mapping->host;
1055 /* This matches the pread()/pwrite() logic */
1056 if (iocb->ki_pos < 0)
1060 ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg],
1061 iocb->ki_nr_segs - iocb->ki_cur_seg,
1064 aio_advance_iovec(iocb, ret);
1066 /* retry all partial writes. retry partial reads as long as its a
1068 } while (ret > 0 && iocb->ki_left > 0 &&
1070 (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))));
1072 /* This means we must have transferred all that we could */
1073 /* No need to retry anymore */
1074 if ((ret == 0) || (iocb->ki_left == 0))
1075 ret = iocb->ki_nbytes - iocb->ki_left;
1077 /* If we managed to write some out we return that, rather than
1078 * the eventual error. */
1080 && ret < 0 && ret != -EIOCBQUEUED
1081 && iocb->ki_nbytes - iocb->ki_left)
1082 ret = iocb->ki_nbytes - iocb->ki_left;
1087 static ssize_t aio_setup_vectored_rw(int rw, struct kiocb *kiocb, bool compat)
1091 kiocb->ki_nr_segs = kiocb->ki_nbytes;
1093 #ifdef CONFIG_COMPAT
1095 ret = compat_rw_copy_check_uvector(rw,
1096 (struct compat_iovec __user *)kiocb->ki_buf,
1097 kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec,
1101 ret = rw_copy_check_uvector(rw,
1102 (struct iovec __user *)kiocb->ki_buf,
1103 kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec,
1108 /* ki_nbytes now reflect bytes instead of segs */
1109 kiocb->ki_nbytes = ret;
1113 static ssize_t aio_setup_single_vector(int rw, struct kiocb *kiocb)
1115 if (unlikely(!access_ok(!rw, kiocb->ki_buf, kiocb->ki_nbytes)))
1118 kiocb->ki_iovec = &kiocb->ki_inline_vec;
1119 kiocb->ki_iovec->iov_base = kiocb->ki_buf;
1120 kiocb->ki_iovec->iov_len = kiocb->ki_nbytes;
1121 kiocb->ki_nr_segs = 1;
1127 * Performs the initial checks and aio retry method
1128 * setup for the kiocb at the time of io submission.
1130 static ssize_t aio_run_iocb(struct kiocb *req, bool compat)
1132 struct file *file = req->ki_filp;
1138 switch (req->ki_opcode) {
1139 case IOCB_CMD_PREAD:
1140 case IOCB_CMD_PREADV:
1143 rw_op = file->f_op->aio_read;
1146 case IOCB_CMD_PWRITE:
1147 case IOCB_CMD_PWRITEV:
1150 rw_op = file->f_op->aio_write;
1153 if (unlikely(!(file->f_mode & mode)))
1159 ret = (req->ki_opcode == IOCB_CMD_PREADV ||
1160 req->ki_opcode == IOCB_CMD_PWRITEV)
1161 ? aio_setup_vectored_rw(rw, req, compat)
1162 : aio_setup_single_vector(rw, req);
1166 ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
1170 req->ki_nbytes = ret;
1173 ret = aio_rw_vect_retry(req, rw, rw_op);
1176 case IOCB_CMD_FDSYNC:
1177 if (!file->f_op->aio_fsync)
1180 ret = file->f_op->aio_fsync(req, 1);
1183 case IOCB_CMD_FSYNC:
1184 if (!file->f_op->aio_fsync)
1187 ret = file->f_op->aio_fsync(req, 0);
1191 pr_debug("EINVAL: no operation provided\n");
1195 if (ret != -EIOCBQUEUED) {
1197 * There's no easy way to restart the syscall since other AIO's
1198 * may be already running. Just fail this IO with EINTR.
1200 if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
1201 ret == -ERESTARTNOHAND || ret == -ERESTART_RESTARTBLOCK))
1203 aio_complete(req, ret, 0);
1209 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1210 struct iocb *iocb, bool compat)
1215 /* enforce forwards compatibility on users */
1216 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
1217 pr_debug("EINVAL: reserve field set\n");
1221 /* prevent overflows */
1223 (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
1224 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
1225 ((ssize_t)iocb->aio_nbytes < 0)
1227 pr_debug("EINVAL: io_submit: overflow check\n");
1231 req = aio_get_req(ctx);
1235 req->ki_filp = fget(iocb->aio_fildes);
1236 if (unlikely(!req->ki_filp)) {
1241 if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1243 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1244 * instance of the file* now. The file descriptor must be
1245 * an eventfd() fd, and will be signaled for each completed
1246 * event using the eventfd_signal() function.
1248 req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
1249 if (IS_ERR(req->ki_eventfd)) {
1250 ret = PTR_ERR(req->ki_eventfd);
1251 req->ki_eventfd = NULL;
1256 ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
1257 if (unlikely(ret)) {
1258 pr_debug("EFAULT: aio_key\n");
1262 req->ki_obj.user = user_iocb;
1263 req->ki_user_data = iocb->aio_data;
1264 req->ki_pos = iocb->aio_offset;
1266 req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf;
1267 req->ki_left = req->ki_nbytes = iocb->aio_nbytes;
1268 req->ki_opcode = iocb->aio_lio_opcode;
1270 ret = aio_run_iocb(req, compat);
1274 aio_put_req(req); /* drop extra ref to req */
1277 put_reqs_available(ctx, 1);
1278 aio_put_req(req); /* drop extra ref to req */
1279 aio_put_req(req); /* drop i/o ref to req */
1283 long do_io_submit(aio_context_t ctx_id, long nr,
1284 struct iocb __user *__user *iocbpp, bool compat)
1289 struct blk_plug plug;
1291 if (unlikely(nr < 0))
1294 if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
1295 nr = LONG_MAX/sizeof(*iocbpp);
1297 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1300 ctx = lookup_ioctx(ctx_id);
1301 if (unlikely(!ctx)) {
1302 pr_debug("EINVAL: invalid context id\n");
1306 blk_start_plug(&plug);
1309 * AKPM: should this return a partial result if some of the IOs were
1310 * successfully submitted?
1312 for (i=0; i<nr; i++) {
1313 struct iocb __user *user_iocb;
1316 if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1321 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1326 ret = io_submit_one(ctx, user_iocb, &tmp, compat);
1330 blk_finish_plug(&plug);
1337 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1338 * the number of iocbs queued. May return -EINVAL if the aio_context
1339 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1340 * *iocbpp[0] is not properly initialized, if the operation specified
1341 * is invalid for the file descriptor in the iocb. May fail with
1342 * -EFAULT if any of the data structures point to invalid data. May
1343 * fail with -EBADF if the file descriptor specified in the first
1344 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1345 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1346 * fail with -ENOSYS if not implemented.
1348 SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
1349 struct iocb __user * __user *, iocbpp)
1351 return do_io_submit(ctx_id, nr, iocbpp, 0);
1355 * Finds a given iocb for cancellation.
1357 static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
1360 struct list_head *pos;
1362 assert_spin_locked(&ctx->ctx_lock);
1364 if (key != KIOCB_KEY)
1367 /* TODO: use a hash or array, this sucks. */
1368 list_for_each(pos, &ctx->active_reqs) {
1369 struct kiocb *kiocb = list_kiocb(pos);
1370 if (kiocb->ki_obj.user == iocb)
1377 * Attempts to cancel an iocb previously passed to io_submit. If
1378 * the operation is successfully cancelled, the resulting event is
1379 * copied into the memory pointed to by result without being placed
1380 * into the completion queue and 0 is returned. May fail with
1381 * -EFAULT if any of the data structures pointed to are invalid.
1382 * May fail with -EINVAL if aio_context specified by ctx_id is
1383 * invalid. May fail with -EAGAIN if the iocb specified was not
1384 * cancelled. Will fail with -ENOSYS if not implemented.
1386 SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
1387 struct io_event __user *, result)
1389 struct io_event res;
1391 struct kiocb *kiocb;
1395 ret = get_user(key, &iocb->aio_key);
1399 ctx = lookup_ioctx(ctx_id);
1403 spin_lock_irq(&ctx->ctx_lock);
1405 kiocb = lookup_kiocb(ctx, iocb, key);
1407 ret = kiocb_cancel(ctx, kiocb, &res);
1411 spin_unlock_irq(&ctx->ctx_lock);
1414 /* Cancellation succeeded -- copy the result
1415 * into the user's buffer.
1417 if (copy_to_user(result, &res, sizeof(res)))
1427 * Attempts to read at least min_nr events and up to nr events from
1428 * the completion queue for the aio_context specified by ctx_id. If
1429 * it succeeds, the number of read events is returned. May fail with
1430 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
1431 * out of range, if timeout is out of range. May fail with -EFAULT
1432 * if any of the memory specified is invalid. May return 0 or
1433 * < min_nr if the timeout specified by timeout has elapsed
1434 * before sufficient events are available, where timeout == NULL
1435 * specifies an infinite timeout. Note that the timeout pointed to by
1436 * timeout is relative and will be updated if not NULL and the
1437 * operation blocks. Will fail with -ENOSYS if not implemented.
1439 SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
1442 struct io_event __user *, events,
1443 struct timespec __user *, timeout)
1445 struct kioctx *ioctx = lookup_ioctx(ctx_id);
1448 if (likely(ioctx)) {
1449 if (likely(min_nr <= nr && min_nr >= 0))
1450 ret = read_events(ioctx, min_nr, nr, events, timeout);