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.
8 * Copyright 2018 Christoph Hellwig.
10 * See ../COPYING for licensing terms.
12 #define pr_fmt(fmt) "%s: " fmt, __func__
14 #include <linux/kernel.h>
15 #include <linux/init.h>
16 #include <linux/errno.h>
17 #include <linux/time.h>
18 #include <linux/aio_abi.h>
19 #include <linux/export.h>
20 #include <linux/syscalls.h>
21 #include <linux/backing-dev.h>
22 #include <linux/refcount.h>
23 #include <linux/uio.h>
25 #include <linux/sched/signal.h>
27 #include <linux/file.h>
29 #include <linux/mman.h>
30 #include <linux/percpu.h>
31 #include <linux/slab.h>
32 #include <linux/timer.h>
33 #include <linux/aio.h>
34 #include <linux/highmem.h>
35 #include <linux/workqueue.h>
36 #include <linux/security.h>
37 #include <linux/eventfd.h>
38 #include <linux/blkdev.h>
39 #include <linux/compat.h>
40 #include <linux/migrate.h>
41 #include <linux/ramfs.h>
42 #include <linux/percpu-refcount.h>
43 #include <linux/mount.h>
44 #include <linux/pseudo_fs.h>
46 #include <linux/uaccess.h>
47 #include <linux/nospec.h>
53 #define AIO_RING_MAGIC 0xa10a10a1
54 #define AIO_RING_COMPAT_FEATURES 1
55 #define AIO_RING_INCOMPAT_FEATURES 0
57 unsigned id
; /* kernel internal index number */
58 unsigned nr
; /* number of io_events */
59 unsigned head
; /* Written to by userland or under ring_lock
60 * mutex by aio_read_events_ring(). */
64 unsigned compat_features
;
65 unsigned incompat_features
;
66 unsigned header_length
; /* size of aio_ring */
69 struct io_event io_events
[];
70 }; /* 128 bytes + ring size */
73 * Plugging is meant to work with larger batches of IOs. If we don't
74 * have more than the below, then don't bother setting up a plug.
76 #define AIO_PLUG_THRESHOLD 2
78 #define AIO_RING_PAGES 8
83 struct kioctx __rcu
*table
[];
87 unsigned reqs_available
;
91 struct completion comp
;
96 struct percpu_ref users
;
99 struct percpu_ref reqs
;
101 unsigned long user_id
;
103 struct __percpu kioctx_cpu
*cpu
;
106 * For percpu reqs_available, number of slots we move to/from global
111 * This is what userspace passed to io_setup(), it's not used for
112 * anything but counting against the global max_reqs quota.
114 * The real limit is nr_events - 1, which will be larger (see
119 /* Size of ringbuffer, in units of struct io_event */
122 unsigned long mmap_base
;
123 unsigned long mmap_size
;
125 struct page
**ring_pages
;
128 struct rcu_work free_rwork
; /* see free_ioctx() */
131 * signals when all in-flight requests are done
133 struct ctx_rq_wait
*rq_wait
;
137 * This counts the number of available slots in the ringbuffer,
138 * so we avoid overflowing it: it's decremented (if positive)
139 * when allocating a kiocb and incremented when the resulting
140 * io_event is pulled off the ringbuffer.
142 * We batch accesses to it with a percpu version.
144 atomic_t reqs_available
;
145 } ____cacheline_aligned_in_smp
;
149 struct list_head active_reqs
; /* used for cancellation */
150 } ____cacheline_aligned_in_smp
;
153 struct mutex ring_lock
;
154 wait_queue_head_t wait
;
155 } ____cacheline_aligned_in_smp
;
159 unsigned completed_events
;
160 spinlock_t completion_lock
;
161 } ____cacheline_aligned_in_smp
;
163 struct page
*internal_pages
[AIO_RING_PAGES
];
164 struct file
*aio_ring_file
;
170 * First field must be the file pointer in all the
171 * iocb unions! See also 'struct kiocb' in <linux/fs.h>
175 struct work_struct work
;
182 struct wait_queue_head
*head
;
186 struct wait_queue_entry wait
;
187 struct work_struct work
;
191 * NOTE! Each of the iocb union members has the file pointer
192 * as the first entry in their struct definition. So you can
193 * access the file pointer through any of the sub-structs,
194 * or directly as just 'ki_filp' in this struct.
198 struct file
*ki_filp
;
200 struct fsync_iocb fsync
;
201 struct poll_iocb poll
;
204 struct kioctx
*ki_ctx
;
205 kiocb_cancel_fn
*ki_cancel
;
207 struct io_event ki_res
;
209 struct list_head ki_list
; /* the aio core uses this
210 * for cancellation */
211 refcount_t ki_refcnt
;
214 * If the aio_resfd field of the userspace iocb is not zero,
215 * this is the underlying eventfd context to deliver events to.
217 struct eventfd_ctx
*ki_eventfd
;
220 /*------ sysctl variables----*/
221 static DEFINE_SPINLOCK(aio_nr_lock
);
222 unsigned long aio_nr
; /* current system wide number of aio requests */
223 unsigned long aio_max_nr
= 0x10000; /* system wide maximum number of aio requests */
224 /*----end sysctl variables---*/
226 static struct kmem_cache
*kiocb_cachep
;
227 static struct kmem_cache
*kioctx_cachep
;
229 static struct vfsmount
*aio_mnt
;
231 static const struct file_operations aio_ring_fops
;
232 static const struct address_space_operations aio_ctx_aops
;
234 static struct file
*aio_private_file(struct kioctx
*ctx
, loff_t nr_pages
)
237 struct inode
*inode
= alloc_anon_inode(aio_mnt
->mnt_sb
);
239 return ERR_CAST(inode
);
241 inode
->i_mapping
->a_ops
= &aio_ctx_aops
;
242 inode
->i_mapping
->private_data
= ctx
;
243 inode
->i_size
= PAGE_SIZE
* nr_pages
;
245 file
= alloc_file_pseudo(inode
, aio_mnt
, "[aio]",
246 O_RDWR
, &aio_ring_fops
);
252 static int aio_init_fs_context(struct fs_context
*fc
)
254 if (!init_pseudo(fc
, AIO_RING_MAGIC
))
256 fc
->s_iflags
|= SB_I_NOEXEC
;
261 * Creates the slab caches used by the aio routines, panic on
262 * failure as this is done early during the boot sequence.
264 static int __init
aio_setup(void)
266 static struct file_system_type aio_fs
= {
268 .init_fs_context
= aio_init_fs_context
,
269 .kill_sb
= kill_anon_super
,
271 aio_mnt
= kern_mount(&aio_fs
);
273 panic("Failed to create aio fs mount.");
275 kiocb_cachep
= KMEM_CACHE(aio_kiocb
, SLAB_HWCACHE_ALIGN
|SLAB_PANIC
);
276 kioctx_cachep
= KMEM_CACHE(kioctx
,SLAB_HWCACHE_ALIGN
|SLAB_PANIC
);
279 __initcall(aio_setup
);
281 static void put_aio_ring_file(struct kioctx
*ctx
)
283 struct file
*aio_ring_file
= ctx
->aio_ring_file
;
284 struct address_space
*i_mapping
;
287 truncate_setsize(file_inode(aio_ring_file
), 0);
289 /* Prevent further access to the kioctx from migratepages */
290 i_mapping
= aio_ring_file
->f_mapping
;
291 spin_lock(&i_mapping
->private_lock
);
292 i_mapping
->private_data
= NULL
;
293 ctx
->aio_ring_file
= NULL
;
294 spin_unlock(&i_mapping
->private_lock
);
300 static void aio_free_ring(struct kioctx
*ctx
)
304 /* Disconnect the kiotx from the ring file. This prevents future
305 * accesses to the kioctx from page migration.
307 put_aio_ring_file(ctx
);
309 for (i
= 0; i
< ctx
->nr_pages
; i
++) {
311 pr_debug("pid(%d) [%d] page->count=%d\n", current
->pid
, i
,
312 page_count(ctx
->ring_pages
[i
]));
313 page
= ctx
->ring_pages
[i
];
316 ctx
->ring_pages
[i
] = NULL
;
320 if (ctx
->ring_pages
&& ctx
->ring_pages
!= ctx
->internal_pages
) {
321 kfree(ctx
->ring_pages
);
322 ctx
->ring_pages
= NULL
;
326 static int aio_ring_mremap(struct vm_area_struct
*vma
)
328 struct file
*file
= vma
->vm_file
;
329 struct mm_struct
*mm
= vma
->vm_mm
;
330 struct kioctx_table
*table
;
331 int i
, res
= -EINVAL
;
333 spin_lock(&mm
->ioctx_lock
);
335 table
= rcu_dereference(mm
->ioctx_table
);
336 for (i
= 0; i
< table
->nr
; i
++) {
339 ctx
= rcu_dereference(table
->table
[i
]);
340 if (ctx
&& ctx
->aio_ring_file
== file
) {
341 if (!atomic_read(&ctx
->dead
)) {
342 ctx
->user_id
= ctx
->mmap_base
= vma
->vm_start
;
350 spin_unlock(&mm
->ioctx_lock
);
354 static const struct vm_operations_struct aio_ring_vm_ops
= {
355 .mremap
= aio_ring_mremap
,
356 #if IS_ENABLED(CONFIG_MMU)
357 .fault
= filemap_fault
,
358 .map_pages
= filemap_map_pages
,
359 .page_mkwrite
= filemap_page_mkwrite
,
363 static int aio_ring_mmap(struct file
*file
, struct vm_area_struct
*vma
)
365 vma
->vm_flags
|= VM_DONTEXPAND
;
366 vma
->vm_ops
= &aio_ring_vm_ops
;
370 static const struct file_operations aio_ring_fops
= {
371 .mmap
= aio_ring_mmap
,
374 #if IS_ENABLED(CONFIG_MIGRATION)
375 static int aio_migratepage(struct address_space
*mapping
, struct page
*new,
376 struct page
*old
, enum migrate_mode mode
)
384 * We cannot support the _NO_COPY case here, because copy needs to
385 * happen under the ctx->completion_lock. That does not work with the
386 * migration workflow of MIGRATE_SYNC_NO_COPY.
388 if (mode
== MIGRATE_SYNC_NO_COPY
)
393 /* mapping->private_lock here protects against the kioctx teardown. */
394 spin_lock(&mapping
->private_lock
);
395 ctx
= mapping
->private_data
;
401 /* The ring_lock mutex. The prevents aio_read_events() from writing
402 * to the ring's head, and prevents page migration from mucking in
403 * a partially initialized kiotx.
405 if (!mutex_trylock(&ctx
->ring_lock
)) {
411 if (idx
< (pgoff_t
)ctx
->nr_pages
) {
412 /* Make sure the old page hasn't already been changed */
413 if (ctx
->ring_pages
[idx
] != old
)
421 /* Writeback must be complete */
422 BUG_ON(PageWriteback(old
));
425 rc
= migrate_page_move_mapping(mapping
, new, old
, 1);
426 if (rc
!= MIGRATEPAGE_SUCCESS
) {
431 /* Take completion_lock to prevent other writes to the ring buffer
432 * while the old page is copied to the new. This prevents new
433 * events from being lost.
435 spin_lock_irqsave(&ctx
->completion_lock
, flags
);
436 migrate_page_copy(new, old
);
437 BUG_ON(ctx
->ring_pages
[idx
] != old
);
438 ctx
->ring_pages
[idx
] = new;
439 spin_unlock_irqrestore(&ctx
->completion_lock
, flags
);
441 /* The old page is no longer accessible. */
445 mutex_unlock(&ctx
->ring_lock
);
447 spin_unlock(&mapping
->private_lock
);
452 static const struct address_space_operations aio_ctx_aops
= {
453 .set_page_dirty
= __set_page_dirty_no_writeback
,
454 #if IS_ENABLED(CONFIG_MIGRATION)
455 .migratepage
= aio_migratepage
,
459 static int aio_setup_ring(struct kioctx
*ctx
, unsigned int nr_events
)
461 struct aio_ring
*ring
;
462 struct mm_struct
*mm
= current
->mm
;
463 unsigned long size
, unused
;
468 /* Compensate for the ring buffer's head/tail overlap entry */
469 nr_events
+= 2; /* 1 is required, 2 for good luck */
471 size
= sizeof(struct aio_ring
);
472 size
+= sizeof(struct io_event
) * nr_events
;
474 nr_pages
= PFN_UP(size
);
478 file
= aio_private_file(ctx
, nr_pages
);
480 ctx
->aio_ring_file
= NULL
;
484 ctx
->aio_ring_file
= file
;
485 nr_events
= (PAGE_SIZE
* nr_pages
- sizeof(struct aio_ring
))
486 / sizeof(struct io_event
);
488 ctx
->ring_pages
= ctx
->internal_pages
;
489 if (nr_pages
> AIO_RING_PAGES
) {
490 ctx
->ring_pages
= kcalloc(nr_pages
, sizeof(struct page
*),
492 if (!ctx
->ring_pages
) {
493 put_aio_ring_file(ctx
);
498 for (i
= 0; i
< nr_pages
; i
++) {
500 page
= find_or_create_page(file
->f_mapping
,
501 i
, GFP_HIGHUSER
| __GFP_ZERO
);
504 pr_debug("pid(%d) page[%d]->count=%d\n",
505 current
->pid
, i
, page_count(page
));
506 SetPageUptodate(page
);
509 ctx
->ring_pages
[i
] = page
;
513 if (unlikely(i
!= nr_pages
)) {
518 ctx
->mmap_size
= nr_pages
* PAGE_SIZE
;
519 pr_debug("attempting mmap of %lu bytes\n", ctx
->mmap_size
);
521 if (mmap_write_lock_killable(mm
)) {
527 ctx
->mmap_base
= do_mmap(ctx
->aio_ring_file
, 0, ctx
->mmap_size
,
528 PROT_READ
| PROT_WRITE
,
529 MAP_SHARED
, 0, &unused
, NULL
);
530 mmap_write_unlock(mm
);
531 if (IS_ERR((void *)ctx
->mmap_base
)) {
537 pr_debug("mmap address: 0x%08lx\n", ctx
->mmap_base
);
539 ctx
->user_id
= ctx
->mmap_base
;
540 ctx
->nr_events
= nr_events
; /* trusted copy */
542 ring
= kmap_atomic(ctx
->ring_pages
[0]);
543 ring
->nr
= nr_events
; /* user copy */
545 ring
->head
= ring
->tail
= 0;
546 ring
->magic
= AIO_RING_MAGIC
;
547 ring
->compat_features
= AIO_RING_COMPAT_FEATURES
;
548 ring
->incompat_features
= AIO_RING_INCOMPAT_FEATURES
;
549 ring
->header_length
= sizeof(struct aio_ring
);
551 flush_dcache_page(ctx
->ring_pages
[0]);
556 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
557 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
558 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
560 void kiocb_set_cancel_fn(struct kiocb
*iocb
, kiocb_cancel_fn
*cancel
)
562 struct aio_kiocb
*req
= container_of(iocb
, struct aio_kiocb
, rw
);
563 struct kioctx
*ctx
= req
->ki_ctx
;
566 if (WARN_ON_ONCE(!list_empty(&req
->ki_list
)))
569 spin_lock_irqsave(&ctx
->ctx_lock
, flags
);
570 list_add_tail(&req
->ki_list
, &ctx
->active_reqs
);
571 req
->ki_cancel
= cancel
;
572 spin_unlock_irqrestore(&ctx
->ctx_lock
, flags
);
574 EXPORT_SYMBOL(kiocb_set_cancel_fn
);
577 * free_ioctx() should be RCU delayed to synchronize against the RCU
578 * protected lookup_ioctx() and also needs process context to call
579 * aio_free_ring(). Use rcu_work.
581 static void free_ioctx(struct work_struct
*work
)
583 struct kioctx
*ctx
= container_of(to_rcu_work(work
), struct kioctx
,
585 pr_debug("freeing %p\n", ctx
);
588 free_percpu(ctx
->cpu
);
589 percpu_ref_exit(&ctx
->reqs
);
590 percpu_ref_exit(&ctx
->users
);
591 kmem_cache_free(kioctx_cachep
, ctx
);
594 static void free_ioctx_reqs(struct percpu_ref
*ref
)
596 struct kioctx
*ctx
= container_of(ref
, struct kioctx
, reqs
);
598 /* At this point we know that there are no any in-flight requests */
599 if (ctx
->rq_wait
&& atomic_dec_and_test(&ctx
->rq_wait
->count
))
600 complete(&ctx
->rq_wait
->comp
);
602 /* Synchronize against RCU protected table->table[] dereferences */
603 INIT_RCU_WORK(&ctx
->free_rwork
, free_ioctx
);
604 queue_rcu_work(system_wq
, &ctx
->free_rwork
);
608 * When this function runs, the kioctx has been removed from the "hash table"
609 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
610 * now it's safe to cancel any that need to be.
612 static void free_ioctx_users(struct percpu_ref
*ref
)
614 struct kioctx
*ctx
= container_of(ref
, struct kioctx
, users
);
615 struct aio_kiocb
*req
;
617 spin_lock_irq(&ctx
->ctx_lock
);
619 while (!list_empty(&ctx
->active_reqs
)) {
620 req
= list_first_entry(&ctx
->active_reqs
,
621 struct aio_kiocb
, ki_list
);
622 req
->ki_cancel(&req
->rw
);
623 list_del_init(&req
->ki_list
);
626 spin_unlock_irq(&ctx
->ctx_lock
);
628 percpu_ref_kill(&ctx
->reqs
);
629 percpu_ref_put(&ctx
->reqs
);
632 static int ioctx_add_table(struct kioctx
*ctx
, struct mm_struct
*mm
)
635 struct kioctx_table
*table
, *old
;
636 struct aio_ring
*ring
;
638 spin_lock(&mm
->ioctx_lock
);
639 table
= rcu_dereference_raw(mm
->ioctx_table
);
643 for (i
= 0; i
< table
->nr
; i
++)
644 if (!rcu_access_pointer(table
->table
[i
])) {
646 rcu_assign_pointer(table
->table
[i
], ctx
);
647 spin_unlock(&mm
->ioctx_lock
);
649 /* While kioctx setup is in progress,
650 * we are protected from page migration
651 * changes ring_pages by ->ring_lock.
653 ring
= kmap_atomic(ctx
->ring_pages
[0]);
659 new_nr
= (table
? table
->nr
: 1) * 4;
660 spin_unlock(&mm
->ioctx_lock
);
662 table
= kzalloc(sizeof(*table
) + sizeof(struct kioctx
*) *
669 spin_lock(&mm
->ioctx_lock
);
670 old
= rcu_dereference_raw(mm
->ioctx_table
);
673 rcu_assign_pointer(mm
->ioctx_table
, table
);
674 } else if (table
->nr
> old
->nr
) {
675 memcpy(table
->table
, old
->table
,
676 old
->nr
* sizeof(struct kioctx
*));
678 rcu_assign_pointer(mm
->ioctx_table
, table
);
687 static void aio_nr_sub(unsigned nr
)
689 spin_lock(&aio_nr_lock
);
690 if (WARN_ON(aio_nr
- nr
> aio_nr
))
694 spin_unlock(&aio_nr_lock
);
698 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
700 static struct kioctx
*ioctx_alloc(unsigned nr_events
)
702 struct mm_struct
*mm
= current
->mm
;
707 * Store the original nr_events -- what userspace passed to io_setup(),
708 * for counting against the global limit -- before it changes.
710 unsigned int max_reqs
= nr_events
;
713 * We keep track of the number of available ringbuffer slots, to prevent
714 * overflow (reqs_available), and we also use percpu counters for this.
716 * So since up to half the slots might be on other cpu's percpu counters
717 * and unavailable, double nr_events so userspace sees what they
718 * expected: additionally, we move req_batch slots to/from percpu
719 * counters at a time, so make sure that isn't 0:
721 nr_events
= max(nr_events
, num_possible_cpus() * 4);
724 /* Prevent overflows */
725 if (nr_events
> (0x10000000U
/ sizeof(struct io_event
))) {
726 pr_debug("ENOMEM: nr_events too high\n");
727 return ERR_PTR(-EINVAL
);
730 if (!nr_events
|| (unsigned long)max_reqs
> aio_max_nr
)
731 return ERR_PTR(-EAGAIN
);
733 ctx
= kmem_cache_zalloc(kioctx_cachep
, GFP_KERNEL
);
735 return ERR_PTR(-ENOMEM
);
737 ctx
->max_reqs
= max_reqs
;
739 spin_lock_init(&ctx
->ctx_lock
);
740 spin_lock_init(&ctx
->completion_lock
);
741 mutex_init(&ctx
->ring_lock
);
742 /* Protect against page migration throughout kiotx setup by keeping
743 * the ring_lock mutex held until setup is complete. */
744 mutex_lock(&ctx
->ring_lock
);
745 init_waitqueue_head(&ctx
->wait
);
747 INIT_LIST_HEAD(&ctx
->active_reqs
);
749 if (percpu_ref_init(&ctx
->users
, free_ioctx_users
, 0, GFP_KERNEL
))
752 if (percpu_ref_init(&ctx
->reqs
, free_ioctx_reqs
, 0, GFP_KERNEL
))
755 ctx
->cpu
= alloc_percpu(struct kioctx_cpu
);
759 err
= aio_setup_ring(ctx
, nr_events
);
763 atomic_set(&ctx
->reqs_available
, ctx
->nr_events
- 1);
764 ctx
->req_batch
= (ctx
->nr_events
- 1) / (num_possible_cpus() * 4);
765 if (ctx
->req_batch
< 1)
768 /* limit the number of system wide aios */
769 spin_lock(&aio_nr_lock
);
770 if (aio_nr
+ ctx
->max_reqs
> aio_max_nr
||
771 aio_nr
+ ctx
->max_reqs
< aio_nr
) {
772 spin_unlock(&aio_nr_lock
);
776 aio_nr
+= ctx
->max_reqs
;
777 spin_unlock(&aio_nr_lock
);
779 percpu_ref_get(&ctx
->users
); /* io_setup() will drop this ref */
780 percpu_ref_get(&ctx
->reqs
); /* free_ioctx_users() will drop this */
782 err
= ioctx_add_table(ctx
, mm
);
786 /* Release the ring_lock mutex now that all setup is complete. */
787 mutex_unlock(&ctx
->ring_lock
);
789 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
790 ctx
, ctx
->user_id
, mm
, ctx
->nr_events
);
794 aio_nr_sub(ctx
->max_reqs
);
796 atomic_set(&ctx
->dead
, 1);
798 vm_munmap(ctx
->mmap_base
, ctx
->mmap_size
);
801 mutex_unlock(&ctx
->ring_lock
);
802 free_percpu(ctx
->cpu
);
803 percpu_ref_exit(&ctx
->reqs
);
804 percpu_ref_exit(&ctx
->users
);
805 kmem_cache_free(kioctx_cachep
, ctx
);
806 pr_debug("error allocating ioctx %d\n", err
);
811 * Cancels all outstanding aio requests on an aio context. Used
812 * when the processes owning a context have all exited to encourage
813 * the rapid destruction of the kioctx.
815 static int kill_ioctx(struct mm_struct
*mm
, struct kioctx
*ctx
,
816 struct ctx_rq_wait
*wait
)
818 struct kioctx_table
*table
;
820 spin_lock(&mm
->ioctx_lock
);
821 if (atomic_xchg(&ctx
->dead
, 1)) {
822 spin_unlock(&mm
->ioctx_lock
);
826 table
= rcu_dereference_raw(mm
->ioctx_table
);
827 WARN_ON(ctx
!= rcu_access_pointer(table
->table
[ctx
->id
]));
828 RCU_INIT_POINTER(table
->table
[ctx
->id
], NULL
);
829 spin_unlock(&mm
->ioctx_lock
);
831 /* free_ioctx_reqs() will do the necessary RCU synchronization */
832 wake_up_all(&ctx
->wait
);
835 * It'd be more correct to do this in free_ioctx(), after all
836 * the outstanding kiocbs have finished - but by then io_destroy
837 * has already returned, so io_setup() could potentially return
838 * -EAGAIN with no ioctxs actually in use (as far as userspace
841 aio_nr_sub(ctx
->max_reqs
);
844 vm_munmap(ctx
->mmap_base
, ctx
->mmap_size
);
847 percpu_ref_kill(&ctx
->users
);
852 * exit_aio: called when the last user of mm goes away. At this point, there is
853 * no way for any new requests to be submited or any of the io_* syscalls to be
854 * called on the context.
856 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
859 void exit_aio(struct mm_struct
*mm
)
861 struct kioctx_table
*table
= rcu_dereference_raw(mm
->ioctx_table
);
862 struct ctx_rq_wait wait
;
868 atomic_set(&wait
.count
, table
->nr
);
869 init_completion(&wait
.comp
);
872 for (i
= 0; i
< table
->nr
; ++i
) {
874 rcu_dereference_protected(table
->table
[i
], true);
882 * We don't need to bother with munmap() here - exit_mmap(mm)
883 * is coming and it'll unmap everything. And we simply can't,
884 * this is not necessarily our ->mm.
885 * Since kill_ioctx() uses non-zero ->mmap_size as indicator
886 * that it needs to unmap the area, just set it to 0.
889 kill_ioctx(mm
, ctx
, &wait
);
892 if (!atomic_sub_and_test(skipped
, &wait
.count
)) {
893 /* Wait until all IO for the context are done. */
894 wait_for_completion(&wait
.comp
);
897 RCU_INIT_POINTER(mm
->ioctx_table
, NULL
);
901 static void put_reqs_available(struct kioctx
*ctx
, unsigned nr
)
903 struct kioctx_cpu
*kcpu
;
906 local_irq_save(flags
);
907 kcpu
= this_cpu_ptr(ctx
->cpu
);
908 kcpu
->reqs_available
+= nr
;
910 while (kcpu
->reqs_available
>= ctx
->req_batch
* 2) {
911 kcpu
->reqs_available
-= ctx
->req_batch
;
912 atomic_add(ctx
->req_batch
, &ctx
->reqs_available
);
915 local_irq_restore(flags
);
918 static bool __get_reqs_available(struct kioctx
*ctx
)
920 struct kioctx_cpu
*kcpu
;
924 local_irq_save(flags
);
925 kcpu
= this_cpu_ptr(ctx
->cpu
);
926 if (!kcpu
->reqs_available
) {
927 int old
, avail
= atomic_read(&ctx
->reqs_available
);
930 if (avail
< ctx
->req_batch
)
934 avail
= atomic_cmpxchg(&ctx
->reqs_available
,
935 avail
, avail
- ctx
->req_batch
);
936 } while (avail
!= old
);
938 kcpu
->reqs_available
+= ctx
->req_batch
;
942 kcpu
->reqs_available
--;
944 local_irq_restore(flags
);
948 /* refill_reqs_available
949 * Updates the reqs_available reference counts used for tracking the
950 * number of free slots in the completion ring. This can be called
951 * from aio_complete() (to optimistically update reqs_available) or
952 * from aio_get_req() (the we're out of events case). It must be
953 * called holding ctx->completion_lock.
955 static void refill_reqs_available(struct kioctx
*ctx
, unsigned head
,
958 unsigned events_in_ring
, completed
;
960 /* Clamp head since userland can write to it. */
961 head
%= ctx
->nr_events
;
963 events_in_ring
= tail
- head
;
965 events_in_ring
= ctx
->nr_events
- (head
- tail
);
967 completed
= ctx
->completed_events
;
968 if (events_in_ring
< completed
)
969 completed
-= events_in_ring
;
976 ctx
->completed_events
-= completed
;
977 put_reqs_available(ctx
, completed
);
980 /* user_refill_reqs_available
981 * Called to refill reqs_available when aio_get_req() encounters an
982 * out of space in the completion ring.
984 static void user_refill_reqs_available(struct kioctx
*ctx
)
986 spin_lock_irq(&ctx
->completion_lock
);
987 if (ctx
->completed_events
) {
988 struct aio_ring
*ring
;
991 /* Access of ring->head may race with aio_read_events_ring()
992 * here, but that's okay since whether we read the old version
993 * or the new version, and either will be valid. The important
994 * part is that head cannot pass tail since we prevent
995 * aio_complete() from updating tail by holding
996 * ctx->completion_lock. Even if head is invalid, the check
997 * against ctx->completed_events below will make sure we do the
1000 ring
= kmap_atomic(ctx
->ring_pages
[0]);
1002 kunmap_atomic(ring
);
1004 refill_reqs_available(ctx
, head
, ctx
->tail
);
1007 spin_unlock_irq(&ctx
->completion_lock
);
1010 static bool get_reqs_available(struct kioctx
*ctx
)
1012 if (__get_reqs_available(ctx
))
1014 user_refill_reqs_available(ctx
);
1015 return __get_reqs_available(ctx
);
1019 * Allocate a slot for an aio request.
1020 * Returns NULL if no requests are free.
1022 * The refcount is initialized to 2 - one for the async op completion,
1023 * one for the synchronous code that does this.
1025 static inline struct aio_kiocb
*aio_get_req(struct kioctx
*ctx
)
1027 struct aio_kiocb
*req
;
1029 req
= kmem_cache_alloc(kiocb_cachep
, GFP_KERNEL
);
1033 if (unlikely(!get_reqs_available(ctx
))) {
1034 kmem_cache_free(kiocb_cachep
, req
);
1038 percpu_ref_get(&ctx
->reqs
);
1040 INIT_LIST_HEAD(&req
->ki_list
);
1041 refcount_set(&req
->ki_refcnt
, 2);
1042 req
->ki_eventfd
= NULL
;
1046 static struct kioctx
*lookup_ioctx(unsigned long ctx_id
)
1048 struct aio_ring __user
*ring
= (void __user
*)ctx_id
;
1049 struct mm_struct
*mm
= current
->mm
;
1050 struct kioctx
*ctx
, *ret
= NULL
;
1051 struct kioctx_table
*table
;
1054 if (get_user(id
, &ring
->id
))
1058 table
= rcu_dereference(mm
->ioctx_table
);
1060 if (!table
|| id
>= table
->nr
)
1063 id
= array_index_nospec(id
, table
->nr
);
1064 ctx
= rcu_dereference(table
->table
[id
]);
1065 if (ctx
&& ctx
->user_id
== ctx_id
) {
1066 if (percpu_ref_tryget_live(&ctx
->users
))
1074 static inline void iocb_destroy(struct aio_kiocb
*iocb
)
1076 if (iocb
->ki_eventfd
)
1077 eventfd_ctx_put(iocb
->ki_eventfd
);
1079 fput(iocb
->ki_filp
);
1080 percpu_ref_put(&iocb
->ki_ctx
->reqs
);
1081 kmem_cache_free(kiocb_cachep
, iocb
);
1085 * Called when the io request on the given iocb is complete.
1087 static void aio_complete(struct aio_kiocb
*iocb
)
1089 struct kioctx
*ctx
= iocb
->ki_ctx
;
1090 struct aio_ring
*ring
;
1091 struct io_event
*ev_page
, *event
;
1092 unsigned tail
, pos
, head
;
1093 unsigned long flags
;
1096 * Add a completion event to the ring buffer. Must be done holding
1097 * ctx->completion_lock to prevent other code from messing with the tail
1098 * pointer since we might be called from irq context.
1100 spin_lock_irqsave(&ctx
->completion_lock
, flags
);
1103 pos
= tail
+ AIO_EVENTS_OFFSET
;
1105 if (++tail
>= ctx
->nr_events
)
1108 ev_page
= kmap_atomic(ctx
->ring_pages
[pos
/ AIO_EVENTS_PER_PAGE
]);
1109 event
= ev_page
+ pos
% AIO_EVENTS_PER_PAGE
;
1111 *event
= iocb
->ki_res
;
1113 kunmap_atomic(ev_page
);
1114 flush_dcache_page(ctx
->ring_pages
[pos
/ AIO_EVENTS_PER_PAGE
]);
1116 pr_debug("%p[%u]: %p: %p %Lx %Lx %Lx\n", ctx
, tail
, iocb
,
1117 (void __user
*)(unsigned long)iocb
->ki_res
.obj
,
1118 iocb
->ki_res
.data
, iocb
->ki_res
.res
, iocb
->ki_res
.res2
);
1120 /* after flagging the request as done, we
1121 * must never even look at it again
1123 smp_wmb(); /* make event visible before updating tail */
1127 ring
= kmap_atomic(ctx
->ring_pages
[0]);
1130 kunmap_atomic(ring
);
1131 flush_dcache_page(ctx
->ring_pages
[0]);
1133 ctx
->completed_events
++;
1134 if (ctx
->completed_events
> 1)
1135 refill_reqs_available(ctx
, head
, tail
);
1136 spin_unlock_irqrestore(&ctx
->completion_lock
, flags
);
1138 pr_debug("added to ring %p at [%u]\n", iocb
, tail
);
1141 * Check if the user asked us to deliver the result through an
1142 * eventfd. The eventfd_signal() function is safe to be called
1145 if (iocb
->ki_eventfd
)
1146 eventfd_signal(iocb
->ki_eventfd
, 1);
1149 * We have to order our ring_info tail store above and test
1150 * of the wait list below outside the wait lock. This is
1151 * like in wake_up_bit() where clearing a bit has to be
1152 * ordered with the unlocked test.
1156 if (waitqueue_active(&ctx
->wait
))
1157 wake_up(&ctx
->wait
);
1160 static inline void iocb_put(struct aio_kiocb
*iocb
)
1162 if (refcount_dec_and_test(&iocb
->ki_refcnt
)) {
1168 /* aio_read_events_ring
1169 * Pull an event off of the ioctx's event ring. Returns the number of
1172 static long aio_read_events_ring(struct kioctx
*ctx
,
1173 struct io_event __user
*event
, long nr
)
1175 struct aio_ring
*ring
;
1176 unsigned head
, tail
, pos
;
1181 * The mutex can block and wake us up and that will cause
1182 * wait_event_interruptible_hrtimeout() to schedule without sleeping
1183 * and repeat. This should be rare enough that it doesn't cause
1184 * peformance issues. See the comment in read_events() for more detail.
1186 sched_annotate_sleep();
1187 mutex_lock(&ctx
->ring_lock
);
1189 /* Access to ->ring_pages here is protected by ctx->ring_lock. */
1190 ring
= kmap_atomic(ctx
->ring_pages
[0]);
1193 kunmap_atomic(ring
);
1196 * Ensure that once we've read the current tail pointer, that
1197 * we also see the events that were stored up to the tail.
1201 pr_debug("h%u t%u m%u\n", head
, tail
, ctx
->nr_events
);
1206 head
%= ctx
->nr_events
;
1207 tail
%= ctx
->nr_events
;
1211 struct io_event
*ev
;
1214 avail
= (head
<= tail
? tail
: ctx
->nr_events
) - head
;
1218 pos
= head
+ AIO_EVENTS_OFFSET
;
1219 page
= ctx
->ring_pages
[pos
/ AIO_EVENTS_PER_PAGE
];
1220 pos
%= AIO_EVENTS_PER_PAGE
;
1222 avail
= min(avail
, nr
- ret
);
1223 avail
= min_t(long, avail
, AIO_EVENTS_PER_PAGE
- pos
);
1226 copy_ret
= copy_to_user(event
+ ret
, ev
+ pos
,
1227 sizeof(*ev
) * avail
);
1230 if (unlikely(copy_ret
)) {
1237 head
%= ctx
->nr_events
;
1240 ring
= kmap_atomic(ctx
->ring_pages
[0]);
1242 kunmap_atomic(ring
);
1243 flush_dcache_page(ctx
->ring_pages
[0]);
1245 pr_debug("%li h%u t%u\n", ret
, head
, tail
);
1247 mutex_unlock(&ctx
->ring_lock
);
1252 static bool aio_read_events(struct kioctx
*ctx
, long min_nr
, long nr
,
1253 struct io_event __user
*event
, long *i
)
1255 long ret
= aio_read_events_ring(ctx
, event
+ *i
, nr
- *i
);
1260 if (unlikely(atomic_read(&ctx
->dead
)))
1266 return ret
< 0 || *i
>= min_nr
;
1269 static long read_events(struct kioctx
*ctx
, long min_nr
, long nr
,
1270 struct io_event __user
*event
,
1276 * Note that aio_read_events() is being called as the conditional - i.e.
1277 * we're calling it after prepare_to_wait() has set task state to
1278 * TASK_INTERRUPTIBLE.
1280 * But aio_read_events() can block, and if it blocks it's going to flip
1281 * the task state back to TASK_RUNNING.
1283 * This should be ok, provided it doesn't flip the state back to
1284 * TASK_RUNNING and return 0 too much - that causes us to spin. That
1285 * will only happen if the mutex_lock() call blocks, and we then find
1286 * the ringbuffer empty. So in practice we should be ok, but it's
1287 * something to be aware of when touching this code.
1290 aio_read_events(ctx
, min_nr
, nr
, event
, &ret
);
1292 wait_event_interruptible_hrtimeout(ctx
->wait
,
1293 aio_read_events(ctx
, min_nr
, nr
, event
, &ret
),
1299 * Create an aio_context capable of receiving at least nr_events.
1300 * ctxp must not point to an aio_context that already exists, and
1301 * must be initialized to 0 prior to the call. On successful
1302 * creation of the aio_context, *ctxp is filled in with the resulting
1303 * handle. May fail with -EINVAL if *ctxp is not initialized,
1304 * if the specified nr_events exceeds internal limits. May fail
1305 * with -EAGAIN if the specified nr_events exceeds the user's limit
1306 * of available events. May fail with -ENOMEM if insufficient kernel
1307 * resources are available. May fail with -EFAULT if an invalid
1308 * pointer is passed for ctxp. Will fail with -ENOSYS if not
1311 SYSCALL_DEFINE2(io_setup
, unsigned, nr_events
, aio_context_t __user
*, ctxp
)
1313 struct kioctx
*ioctx
= NULL
;
1317 ret
= get_user(ctx
, ctxp
);
1322 if (unlikely(ctx
|| nr_events
== 0)) {
1323 pr_debug("EINVAL: ctx %lu nr_events %u\n",
1328 ioctx
= ioctx_alloc(nr_events
);
1329 ret
= PTR_ERR(ioctx
);
1330 if (!IS_ERR(ioctx
)) {
1331 ret
= put_user(ioctx
->user_id
, ctxp
);
1333 kill_ioctx(current
->mm
, ioctx
, NULL
);
1334 percpu_ref_put(&ioctx
->users
);
1341 #ifdef CONFIG_COMPAT
1342 COMPAT_SYSCALL_DEFINE2(io_setup
, unsigned, nr_events
, u32 __user
*, ctx32p
)
1344 struct kioctx
*ioctx
= NULL
;
1348 ret
= get_user(ctx
, ctx32p
);
1353 if (unlikely(ctx
|| nr_events
== 0)) {
1354 pr_debug("EINVAL: ctx %lu nr_events %u\n",
1359 ioctx
= ioctx_alloc(nr_events
);
1360 ret
= PTR_ERR(ioctx
);
1361 if (!IS_ERR(ioctx
)) {
1362 /* truncating is ok because it's a user address */
1363 ret
= put_user((u32
)ioctx
->user_id
, ctx32p
);
1365 kill_ioctx(current
->mm
, ioctx
, NULL
);
1366 percpu_ref_put(&ioctx
->users
);
1375 * Destroy the aio_context specified. May cancel any outstanding
1376 * AIOs and block on completion. Will fail with -ENOSYS if not
1377 * implemented. May fail with -EINVAL if the context pointed to
1380 SYSCALL_DEFINE1(io_destroy
, aio_context_t
, ctx
)
1382 struct kioctx
*ioctx
= lookup_ioctx(ctx
);
1383 if (likely(NULL
!= ioctx
)) {
1384 struct ctx_rq_wait wait
;
1387 init_completion(&wait
.comp
);
1388 atomic_set(&wait
.count
, 1);
1390 /* Pass requests_done to kill_ioctx() where it can be set
1391 * in a thread-safe way. If we try to set it here then we have
1392 * a race condition if two io_destroy() called simultaneously.
1394 ret
= kill_ioctx(current
->mm
, ioctx
, &wait
);
1395 percpu_ref_put(&ioctx
->users
);
1397 /* Wait until all IO for the context are done. Otherwise kernel
1398 * keep using user-space buffers even if user thinks the context
1402 wait_for_completion(&wait
.comp
);
1406 pr_debug("EINVAL: invalid context id\n");
1410 static void aio_remove_iocb(struct aio_kiocb
*iocb
)
1412 struct kioctx
*ctx
= iocb
->ki_ctx
;
1413 unsigned long flags
;
1415 spin_lock_irqsave(&ctx
->ctx_lock
, flags
);
1416 list_del(&iocb
->ki_list
);
1417 spin_unlock_irqrestore(&ctx
->ctx_lock
, flags
);
1420 static void aio_complete_rw(struct kiocb
*kiocb
, long res
, long res2
)
1422 struct aio_kiocb
*iocb
= container_of(kiocb
, struct aio_kiocb
, rw
);
1424 if (!list_empty_careful(&iocb
->ki_list
))
1425 aio_remove_iocb(iocb
);
1427 if (kiocb
->ki_flags
& IOCB_WRITE
) {
1428 struct inode
*inode
= file_inode(kiocb
->ki_filp
);
1431 * Tell lockdep we inherited freeze protection from submission
1434 if (S_ISREG(inode
->i_mode
))
1435 __sb_writers_acquired(inode
->i_sb
, SB_FREEZE_WRITE
);
1436 file_end_write(kiocb
->ki_filp
);
1439 iocb
->ki_res
.res
= res
;
1440 iocb
->ki_res
.res2
= res2
;
1444 static int aio_prep_rw(struct kiocb
*req
, const struct iocb
*iocb
)
1448 req
->ki_complete
= aio_complete_rw
;
1449 req
->private = NULL
;
1450 req
->ki_pos
= iocb
->aio_offset
;
1451 req
->ki_flags
= iocb_flags(req
->ki_filp
);
1452 if (iocb
->aio_flags
& IOCB_FLAG_RESFD
)
1453 req
->ki_flags
|= IOCB_EVENTFD
;
1454 req
->ki_hint
= ki_hint_validate(file_write_hint(req
->ki_filp
));
1455 if (iocb
->aio_flags
& IOCB_FLAG_IOPRIO
) {
1457 * If the IOCB_FLAG_IOPRIO flag of aio_flags is set, then
1458 * aio_reqprio is interpreted as an I/O scheduling
1459 * class and priority.
1461 ret
= ioprio_check_cap(iocb
->aio_reqprio
);
1463 pr_debug("aio ioprio check cap error: %d\n", ret
);
1467 req
->ki_ioprio
= iocb
->aio_reqprio
;
1469 req
->ki_ioprio
= get_current_ioprio();
1471 ret
= kiocb_set_rw_flags(req
, iocb
->aio_rw_flags
);
1475 req
->ki_flags
&= ~IOCB_HIPRI
; /* no one is going to poll for this I/O */
1479 static ssize_t
aio_setup_rw(int rw
, const struct iocb
*iocb
,
1480 struct iovec
**iovec
, bool vectored
, bool compat
,
1481 struct iov_iter
*iter
)
1483 void __user
*buf
= (void __user
*)(uintptr_t)iocb
->aio_buf
;
1484 size_t len
= iocb
->aio_nbytes
;
1487 ssize_t ret
= import_single_range(rw
, buf
, len
, *iovec
, iter
);
1492 return __import_iovec(rw
, buf
, len
, UIO_FASTIOV
, iovec
, iter
, compat
);
1495 static inline void aio_rw_done(struct kiocb
*req
, ssize_t ret
)
1501 case -ERESTARTNOINTR
:
1502 case -ERESTARTNOHAND
:
1503 case -ERESTART_RESTARTBLOCK
:
1505 * There's no easy way to restart the syscall since other AIO's
1506 * may be already running. Just fail this IO with EINTR.
1511 req
->ki_complete(req
, ret
, 0);
1515 static int aio_read(struct kiocb
*req
, const struct iocb
*iocb
,
1516 bool vectored
, bool compat
)
1518 struct iovec inline_vecs
[UIO_FASTIOV
], *iovec
= inline_vecs
;
1519 struct iov_iter iter
;
1523 ret
= aio_prep_rw(req
, iocb
);
1526 file
= req
->ki_filp
;
1527 if (unlikely(!(file
->f_mode
& FMODE_READ
)))
1530 if (unlikely(!file
->f_op
->read_iter
))
1533 ret
= aio_setup_rw(READ
, iocb
, &iovec
, vectored
, compat
, &iter
);
1536 ret
= rw_verify_area(READ
, file
, &req
->ki_pos
, iov_iter_count(&iter
));
1538 aio_rw_done(req
, call_read_iter(file
, req
, &iter
));
1543 static int aio_write(struct kiocb
*req
, const struct iocb
*iocb
,
1544 bool vectored
, bool compat
)
1546 struct iovec inline_vecs
[UIO_FASTIOV
], *iovec
= inline_vecs
;
1547 struct iov_iter iter
;
1551 ret
= aio_prep_rw(req
, iocb
);
1554 file
= req
->ki_filp
;
1556 if (unlikely(!(file
->f_mode
& FMODE_WRITE
)))
1558 if (unlikely(!file
->f_op
->write_iter
))
1561 ret
= aio_setup_rw(WRITE
, iocb
, &iovec
, vectored
, compat
, &iter
);
1564 ret
= rw_verify_area(WRITE
, file
, &req
->ki_pos
, iov_iter_count(&iter
));
1567 * Open-code file_start_write here to grab freeze protection,
1568 * which will be released by another thread in
1569 * aio_complete_rw(). Fool lockdep by telling it the lock got
1570 * released so that it doesn't complain about the held lock when
1571 * we return to userspace.
1573 if (S_ISREG(file_inode(file
)->i_mode
)) {
1574 sb_start_write(file_inode(file
)->i_sb
);
1575 __sb_writers_release(file_inode(file
)->i_sb
, SB_FREEZE_WRITE
);
1577 req
->ki_flags
|= IOCB_WRITE
;
1578 aio_rw_done(req
, call_write_iter(file
, req
, &iter
));
1584 static void aio_fsync_work(struct work_struct
*work
)
1586 struct aio_kiocb
*iocb
= container_of(work
, struct aio_kiocb
, fsync
.work
);
1587 const struct cred
*old_cred
= override_creds(iocb
->fsync
.creds
);
1589 iocb
->ki_res
.res
= vfs_fsync(iocb
->fsync
.file
, iocb
->fsync
.datasync
);
1590 revert_creds(old_cred
);
1591 put_cred(iocb
->fsync
.creds
);
1595 static int aio_fsync(struct fsync_iocb
*req
, const struct iocb
*iocb
,
1598 if (unlikely(iocb
->aio_buf
|| iocb
->aio_offset
|| iocb
->aio_nbytes
||
1599 iocb
->aio_rw_flags
))
1602 if (unlikely(!req
->file
->f_op
->fsync
))
1605 req
->creds
= prepare_creds();
1609 req
->datasync
= datasync
;
1610 INIT_WORK(&req
->work
, aio_fsync_work
);
1611 schedule_work(&req
->work
);
1615 static void aio_poll_put_work(struct work_struct
*work
)
1617 struct poll_iocb
*req
= container_of(work
, struct poll_iocb
, work
);
1618 struct aio_kiocb
*iocb
= container_of(req
, struct aio_kiocb
, poll
);
1623 static void aio_poll_complete_work(struct work_struct
*work
)
1625 struct poll_iocb
*req
= container_of(work
, struct poll_iocb
, work
);
1626 struct aio_kiocb
*iocb
= container_of(req
, struct aio_kiocb
, poll
);
1627 struct poll_table_struct pt
= { ._key
= req
->events
};
1628 struct kioctx
*ctx
= iocb
->ki_ctx
;
1631 if (!READ_ONCE(req
->cancelled
))
1632 mask
= vfs_poll(req
->file
, &pt
) & req
->events
;
1635 * Note that ->ki_cancel callers also delete iocb from active_reqs after
1636 * calling ->ki_cancel. We need the ctx_lock roundtrip here to
1637 * synchronize with them. In the cancellation case the list_del_init
1638 * itself is not actually needed, but harmless so we keep it in to
1639 * avoid further branches in the fast path.
1641 spin_lock_irq(&ctx
->ctx_lock
);
1642 if (!mask
&& !READ_ONCE(req
->cancelled
)) {
1643 add_wait_queue(req
->head
, &req
->wait
);
1644 spin_unlock_irq(&ctx
->ctx_lock
);
1647 list_del_init(&iocb
->ki_list
);
1648 iocb
->ki_res
.res
= mangle_poll(mask
);
1650 spin_unlock_irq(&ctx
->ctx_lock
);
1655 /* assumes we are called with irqs disabled */
1656 static int aio_poll_cancel(struct kiocb
*iocb
)
1658 struct aio_kiocb
*aiocb
= container_of(iocb
, struct aio_kiocb
, rw
);
1659 struct poll_iocb
*req
= &aiocb
->poll
;
1661 spin_lock(&req
->head
->lock
);
1662 WRITE_ONCE(req
->cancelled
, true);
1663 if (!list_empty(&req
->wait
.entry
)) {
1664 list_del_init(&req
->wait
.entry
);
1665 schedule_work(&aiocb
->poll
.work
);
1667 spin_unlock(&req
->head
->lock
);
1672 static int aio_poll_wake(struct wait_queue_entry
*wait
, unsigned mode
, int sync
,
1675 struct poll_iocb
*req
= container_of(wait
, struct poll_iocb
, wait
);
1676 struct aio_kiocb
*iocb
= container_of(req
, struct aio_kiocb
, poll
);
1677 __poll_t mask
= key_to_poll(key
);
1678 unsigned long flags
;
1680 /* for instances that support it check for an event match first: */
1681 if (mask
&& !(mask
& req
->events
))
1684 list_del_init(&req
->wait
.entry
);
1686 if (mask
&& spin_trylock_irqsave(&iocb
->ki_ctx
->ctx_lock
, flags
)) {
1687 struct kioctx
*ctx
= iocb
->ki_ctx
;
1690 * Try to complete the iocb inline if we can. Use
1691 * irqsave/irqrestore because not all filesystems (e.g. fuse)
1692 * call this function with IRQs disabled and because IRQs
1693 * have to be disabled before ctx_lock is obtained.
1695 list_del(&iocb
->ki_list
);
1696 iocb
->ki_res
.res
= mangle_poll(mask
);
1698 if (iocb
->ki_eventfd
&& eventfd_signal_allowed()) {
1700 INIT_WORK(&req
->work
, aio_poll_put_work
);
1701 schedule_work(&req
->work
);
1703 spin_unlock_irqrestore(&ctx
->ctx_lock
, flags
);
1707 schedule_work(&req
->work
);
1712 struct aio_poll_table
{
1713 struct poll_table_struct pt
;
1714 struct aio_kiocb
*iocb
;
1719 aio_poll_queue_proc(struct file
*file
, struct wait_queue_head
*head
,
1720 struct poll_table_struct
*p
)
1722 struct aio_poll_table
*pt
= container_of(p
, struct aio_poll_table
, pt
);
1724 /* multiple wait queues per file are not supported */
1725 if (unlikely(pt
->iocb
->poll
.head
)) {
1726 pt
->error
= -EINVAL
;
1731 pt
->iocb
->poll
.head
= head
;
1732 add_wait_queue(head
, &pt
->iocb
->poll
.wait
);
1735 static int aio_poll(struct aio_kiocb
*aiocb
, const struct iocb
*iocb
)
1737 struct kioctx
*ctx
= aiocb
->ki_ctx
;
1738 struct poll_iocb
*req
= &aiocb
->poll
;
1739 struct aio_poll_table apt
;
1740 bool cancel
= false;
1743 /* reject any unknown events outside the normal event mask. */
1744 if ((u16
)iocb
->aio_buf
!= iocb
->aio_buf
)
1746 /* reject fields that are not defined for poll */
1747 if (iocb
->aio_offset
|| iocb
->aio_nbytes
|| iocb
->aio_rw_flags
)
1750 INIT_WORK(&req
->work
, aio_poll_complete_work
);
1751 req
->events
= demangle_poll(iocb
->aio_buf
) | EPOLLERR
| EPOLLHUP
;
1755 req
->cancelled
= false;
1757 apt
.pt
._qproc
= aio_poll_queue_proc
;
1758 apt
.pt
._key
= req
->events
;
1760 apt
.error
= -EINVAL
; /* same as no support for IOCB_CMD_POLL */
1762 /* initialized the list so that we can do list_empty checks */
1763 INIT_LIST_HEAD(&req
->wait
.entry
);
1764 init_waitqueue_func_entry(&req
->wait
, aio_poll_wake
);
1766 mask
= vfs_poll(req
->file
, &apt
.pt
) & req
->events
;
1767 spin_lock_irq(&ctx
->ctx_lock
);
1768 if (likely(req
->head
)) {
1769 spin_lock(&req
->head
->lock
);
1770 if (unlikely(list_empty(&req
->wait
.entry
))) {
1776 if (mask
|| apt
.error
) {
1777 list_del_init(&req
->wait
.entry
);
1778 } else if (cancel
) {
1779 WRITE_ONCE(req
->cancelled
, true);
1780 } else if (!req
->done
) { /* actually waiting for an event */
1781 list_add_tail(&aiocb
->ki_list
, &ctx
->active_reqs
);
1782 aiocb
->ki_cancel
= aio_poll_cancel
;
1784 spin_unlock(&req
->head
->lock
);
1786 if (mask
) { /* no async, we'd stolen it */
1787 aiocb
->ki_res
.res
= mangle_poll(mask
);
1790 spin_unlock_irq(&ctx
->ctx_lock
);
1796 static int __io_submit_one(struct kioctx
*ctx
, const struct iocb
*iocb
,
1797 struct iocb __user
*user_iocb
, struct aio_kiocb
*req
,
1800 req
->ki_filp
= fget(iocb
->aio_fildes
);
1801 if (unlikely(!req
->ki_filp
))
1804 if (iocb
->aio_flags
& IOCB_FLAG_RESFD
) {
1805 struct eventfd_ctx
*eventfd
;
1807 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1808 * instance of the file* now. The file descriptor must be
1809 * an eventfd() fd, and will be signaled for each completed
1810 * event using the eventfd_signal() function.
1812 eventfd
= eventfd_ctx_fdget(iocb
->aio_resfd
);
1813 if (IS_ERR(eventfd
))
1814 return PTR_ERR(eventfd
);
1816 req
->ki_eventfd
= eventfd
;
1819 if (unlikely(put_user(KIOCB_KEY
, &user_iocb
->aio_key
))) {
1820 pr_debug("EFAULT: aio_key\n");
1824 req
->ki_res
.obj
= (u64
)(unsigned long)user_iocb
;
1825 req
->ki_res
.data
= iocb
->aio_data
;
1826 req
->ki_res
.res
= 0;
1827 req
->ki_res
.res2
= 0;
1829 switch (iocb
->aio_lio_opcode
) {
1830 case IOCB_CMD_PREAD
:
1831 return aio_read(&req
->rw
, iocb
, false, compat
);
1832 case IOCB_CMD_PWRITE
:
1833 return aio_write(&req
->rw
, iocb
, false, compat
);
1834 case IOCB_CMD_PREADV
:
1835 return aio_read(&req
->rw
, iocb
, true, compat
);
1836 case IOCB_CMD_PWRITEV
:
1837 return aio_write(&req
->rw
, iocb
, true, compat
);
1838 case IOCB_CMD_FSYNC
:
1839 return aio_fsync(&req
->fsync
, iocb
, false);
1840 case IOCB_CMD_FDSYNC
:
1841 return aio_fsync(&req
->fsync
, iocb
, true);
1843 return aio_poll(req
, iocb
);
1845 pr_debug("invalid aio operation %d\n", iocb
->aio_lio_opcode
);
1850 static int io_submit_one(struct kioctx
*ctx
, struct iocb __user
*user_iocb
,
1853 struct aio_kiocb
*req
;
1857 if (unlikely(copy_from_user(&iocb
, user_iocb
, sizeof(iocb
))))
1860 /* enforce forwards compatibility on users */
1861 if (unlikely(iocb
.aio_reserved2
)) {
1862 pr_debug("EINVAL: reserve field set\n");
1866 /* prevent overflows */
1868 (iocb
.aio_buf
!= (unsigned long)iocb
.aio_buf
) ||
1869 (iocb
.aio_nbytes
!= (size_t)iocb
.aio_nbytes
) ||
1870 ((ssize_t
)iocb
.aio_nbytes
< 0)
1872 pr_debug("EINVAL: overflow check\n");
1876 req
= aio_get_req(ctx
);
1880 err
= __io_submit_one(ctx
, &iocb
, user_iocb
, req
, compat
);
1882 /* Done with the synchronous reference */
1886 * If err is 0, we'd either done aio_complete() ourselves or have
1887 * arranged for that to be done asynchronously. Anything non-zero
1888 * means that we need to destroy req ourselves.
1890 if (unlikely(err
)) {
1892 put_reqs_available(ctx
, 1);
1898 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1899 * the number of iocbs queued. May return -EINVAL if the aio_context
1900 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1901 * *iocbpp[0] is not properly initialized, if the operation specified
1902 * is invalid for the file descriptor in the iocb. May fail with
1903 * -EFAULT if any of the data structures point to invalid data. May
1904 * fail with -EBADF if the file descriptor specified in the first
1905 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1906 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1907 * fail with -ENOSYS if not implemented.
1909 SYSCALL_DEFINE3(io_submit
, aio_context_t
, ctx_id
, long, nr
,
1910 struct iocb __user
* __user
*, iocbpp
)
1915 struct blk_plug plug
;
1917 if (unlikely(nr
< 0))
1920 ctx
= lookup_ioctx(ctx_id
);
1921 if (unlikely(!ctx
)) {
1922 pr_debug("EINVAL: invalid context id\n");
1926 if (nr
> ctx
->nr_events
)
1927 nr
= ctx
->nr_events
;
1929 if (nr
> AIO_PLUG_THRESHOLD
)
1930 blk_start_plug(&plug
);
1931 for (i
= 0; i
< nr
; i
++) {
1932 struct iocb __user
*user_iocb
;
1934 if (unlikely(get_user(user_iocb
, iocbpp
+ i
))) {
1939 ret
= io_submit_one(ctx
, user_iocb
, false);
1943 if (nr
> AIO_PLUG_THRESHOLD
)
1944 blk_finish_plug(&plug
);
1946 percpu_ref_put(&ctx
->users
);
1950 #ifdef CONFIG_COMPAT
1951 COMPAT_SYSCALL_DEFINE3(io_submit
, compat_aio_context_t
, ctx_id
,
1952 int, nr
, compat_uptr_t __user
*, iocbpp
)
1957 struct blk_plug plug
;
1959 if (unlikely(nr
< 0))
1962 ctx
= lookup_ioctx(ctx_id
);
1963 if (unlikely(!ctx
)) {
1964 pr_debug("EINVAL: invalid context id\n");
1968 if (nr
> ctx
->nr_events
)
1969 nr
= ctx
->nr_events
;
1971 if (nr
> AIO_PLUG_THRESHOLD
)
1972 blk_start_plug(&plug
);
1973 for (i
= 0; i
< nr
; i
++) {
1974 compat_uptr_t user_iocb
;
1976 if (unlikely(get_user(user_iocb
, iocbpp
+ i
))) {
1981 ret
= io_submit_one(ctx
, compat_ptr(user_iocb
), true);
1985 if (nr
> AIO_PLUG_THRESHOLD
)
1986 blk_finish_plug(&plug
);
1988 percpu_ref_put(&ctx
->users
);
1994 * Attempts to cancel an iocb previously passed to io_submit. If
1995 * the operation is successfully cancelled, the resulting event is
1996 * copied into the memory pointed to by result without being placed
1997 * into the completion queue and 0 is returned. May fail with
1998 * -EFAULT if any of the data structures pointed to are invalid.
1999 * May fail with -EINVAL if aio_context specified by ctx_id is
2000 * invalid. May fail with -EAGAIN if the iocb specified was not
2001 * cancelled. Will fail with -ENOSYS if not implemented.
2003 SYSCALL_DEFINE3(io_cancel
, aio_context_t
, ctx_id
, struct iocb __user
*, iocb
,
2004 struct io_event __user
*, result
)
2007 struct aio_kiocb
*kiocb
;
2010 u64 obj
= (u64
)(unsigned long)iocb
;
2012 if (unlikely(get_user(key
, &iocb
->aio_key
)))
2014 if (unlikely(key
!= KIOCB_KEY
))
2017 ctx
= lookup_ioctx(ctx_id
);
2021 spin_lock_irq(&ctx
->ctx_lock
);
2022 /* TODO: use a hash or array, this sucks. */
2023 list_for_each_entry(kiocb
, &ctx
->active_reqs
, ki_list
) {
2024 if (kiocb
->ki_res
.obj
== obj
) {
2025 ret
= kiocb
->ki_cancel(&kiocb
->rw
);
2026 list_del_init(&kiocb
->ki_list
);
2030 spin_unlock_irq(&ctx
->ctx_lock
);
2034 * The result argument is no longer used - the io_event is
2035 * always delivered via the ring buffer. -EINPROGRESS indicates
2036 * cancellation is progress:
2041 percpu_ref_put(&ctx
->users
);
2046 static long do_io_getevents(aio_context_t ctx_id
,
2049 struct io_event __user
*events
,
2050 struct timespec64
*ts
)
2052 ktime_t until
= ts
? timespec64_to_ktime(*ts
) : KTIME_MAX
;
2053 struct kioctx
*ioctx
= lookup_ioctx(ctx_id
);
2056 if (likely(ioctx
)) {
2057 if (likely(min_nr
<= nr
&& min_nr
>= 0))
2058 ret
= read_events(ioctx
, min_nr
, nr
, events
, until
);
2059 percpu_ref_put(&ioctx
->users
);
2066 * Attempts to read at least min_nr events and up to nr events from
2067 * the completion queue for the aio_context specified by ctx_id. If
2068 * it succeeds, the number of read events is returned. May fail with
2069 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
2070 * out of range, if timeout is out of range. May fail with -EFAULT
2071 * if any of the memory specified is invalid. May return 0 or
2072 * < min_nr if the timeout specified by timeout has elapsed
2073 * before sufficient events are available, where timeout == NULL
2074 * specifies an infinite timeout. Note that the timeout pointed to by
2075 * timeout is relative. Will fail with -ENOSYS if not implemented.
2079 SYSCALL_DEFINE5(io_getevents
, aio_context_t
, ctx_id
,
2082 struct io_event __user
*, events
,
2083 struct __kernel_timespec __user
*, timeout
)
2085 struct timespec64 ts
;
2088 if (timeout
&& unlikely(get_timespec64(&ts
, timeout
)))
2091 ret
= do_io_getevents(ctx_id
, min_nr
, nr
, events
, timeout
? &ts
: NULL
);
2092 if (!ret
&& signal_pending(current
))
2099 struct __aio_sigset
{
2100 const sigset_t __user
*sigmask
;
2104 SYSCALL_DEFINE6(io_pgetevents
,
2105 aio_context_t
, ctx_id
,
2108 struct io_event __user
*, events
,
2109 struct __kernel_timespec __user
*, timeout
,
2110 const struct __aio_sigset __user
*, usig
)
2112 struct __aio_sigset ksig
= { NULL
, };
2113 struct timespec64 ts
;
2117 if (timeout
&& unlikely(get_timespec64(&ts
, timeout
)))
2120 if (usig
&& copy_from_user(&ksig
, usig
, sizeof(ksig
)))
2123 ret
= set_user_sigmask(ksig
.sigmask
, ksig
.sigsetsize
);
2127 ret
= do_io_getevents(ctx_id
, min_nr
, nr
, events
, timeout
? &ts
: NULL
);
2129 interrupted
= signal_pending(current
);
2130 restore_saved_sigmask_unless(interrupted
);
2131 if (interrupted
&& !ret
)
2132 ret
= -ERESTARTNOHAND
;
2137 #if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)
2139 SYSCALL_DEFINE6(io_pgetevents_time32
,
2140 aio_context_t
, ctx_id
,
2143 struct io_event __user
*, events
,
2144 struct old_timespec32 __user
*, timeout
,
2145 const struct __aio_sigset __user
*, usig
)
2147 struct __aio_sigset ksig
= { NULL
, };
2148 struct timespec64 ts
;
2152 if (timeout
&& unlikely(get_old_timespec32(&ts
, timeout
)))
2155 if (usig
&& copy_from_user(&ksig
, usig
, sizeof(ksig
)))
2159 ret
= set_user_sigmask(ksig
.sigmask
, ksig
.sigsetsize
);
2163 ret
= do_io_getevents(ctx_id
, min_nr
, nr
, events
, timeout
? &ts
: NULL
);
2165 interrupted
= signal_pending(current
);
2166 restore_saved_sigmask_unless(interrupted
);
2167 if (interrupted
&& !ret
)
2168 ret
= -ERESTARTNOHAND
;
2175 #if defined(CONFIG_COMPAT_32BIT_TIME)
2177 SYSCALL_DEFINE5(io_getevents_time32
, __u32
, ctx_id
,
2180 struct io_event __user
*, events
,
2181 struct old_timespec32 __user
*, timeout
)
2183 struct timespec64 t
;
2186 if (timeout
&& get_old_timespec32(&t
, timeout
))
2189 ret
= do_io_getevents(ctx_id
, min_nr
, nr
, events
, timeout
? &t
: NULL
);
2190 if (!ret
&& signal_pending(current
))
2197 #ifdef CONFIG_COMPAT
2199 struct __compat_aio_sigset
{
2200 compat_uptr_t sigmask
;
2201 compat_size_t sigsetsize
;
2204 #if defined(CONFIG_COMPAT_32BIT_TIME)
2206 COMPAT_SYSCALL_DEFINE6(io_pgetevents
,
2207 compat_aio_context_t
, ctx_id
,
2208 compat_long_t
, min_nr
,
2210 struct io_event __user
*, events
,
2211 struct old_timespec32 __user
*, timeout
,
2212 const struct __compat_aio_sigset __user
*, usig
)
2214 struct __compat_aio_sigset ksig
= { 0, };
2215 struct timespec64 t
;
2219 if (timeout
&& get_old_timespec32(&t
, timeout
))
2222 if (usig
&& copy_from_user(&ksig
, usig
, sizeof(ksig
)))
2225 ret
= set_compat_user_sigmask(compat_ptr(ksig
.sigmask
), ksig
.sigsetsize
);
2229 ret
= do_io_getevents(ctx_id
, min_nr
, nr
, events
, timeout
? &t
: NULL
);
2231 interrupted
= signal_pending(current
);
2232 restore_saved_sigmask_unless(interrupted
);
2233 if (interrupted
&& !ret
)
2234 ret
= -ERESTARTNOHAND
;
2241 COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64
,
2242 compat_aio_context_t
, ctx_id
,
2243 compat_long_t
, min_nr
,
2245 struct io_event __user
*, events
,
2246 struct __kernel_timespec __user
*, timeout
,
2247 const struct __compat_aio_sigset __user
*, usig
)
2249 struct __compat_aio_sigset ksig
= { 0, };
2250 struct timespec64 t
;
2254 if (timeout
&& get_timespec64(&t
, timeout
))
2257 if (usig
&& copy_from_user(&ksig
, usig
, sizeof(ksig
)))
2260 ret
= set_compat_user_sigmask(compat_ptr(ksig
.sigmask
), ksig
.sigsetsize
);
2264 ret
= do_io_getevents(ctx_id
, min_nr
, nr
, events
, timeout
? &t
: NULL
);
2266 interrupted
= signal_pending(current
);
2267 restore_saved_sigmask_unless(interrupted
);
2268 if (interrupted
&& !ret
)
2269 ret
= -ERESTARTNOHAND
;