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/mmu_context.h>
31 #include <linux/percpu.h>
32 #include <linux/slab.h>
33 #include <linux/timer.h>
34 #include <linux/aio.h>
35 #include <linux/highmem.h>
36 #include <linux/workqueue.h>
37 #include <linux/security.h>
38 #include <linux/eventfd.h>
39 #include <linux/blkdev.h>
40 #include <linux/compat.h>
41 #include <linux/migrate.h>
42 #include <linux/ramfs.h>
43 #include <linux/percpu-refcount.h>
44 #include <linux/mount.h>
46 #include <asm/kmap_types.h>
47 #include <linux/uaccess.h>
48 #include <linux/nospec.h>
54 #define AIO_RING_MAGIC 0xa10a10a1
55 #define AIO_RING_COMPAT_FEATURES 1
56 #define AIO_RING_INCOMPAT_FEATURES 0
58 unsigned id
; /* kernel internal index number */
59 unsigned nr
; /* number of io_events */
60 unsigned head
; /* Written to by userland or under ring_lock
61 * mutex by aio_read_events_ring(). */
65 unsigned compat_features
;
66 unsigned incompat_features
;
67 unsigned header_length
; /* size of aio_ring */
70 struct io_event io_events
[0];
71 }; /* 128 bytes + ring size */
74 * Plugging is meant to work with larger batches of IOs. If we don't
75 * have more than the below, then don't bother setting up a plug.
77 #define AIO_PLUG_THRESHOLD 2
79 #define AIO_RING_PAGES 8
84 struct kioctx __rcu
*table
[];
88 unsigned reqs_available
;
92 struct completion comp
;
97 struct percpu_ref users
;
100 struct percpu_ref reqs
;
102 unsigned long user_id
;
104 struct __percpu kioctx_cpu
*cpu
;
107 * For percpu reqs_available, number of slots we move to/from global
112 * This is what userspace passed to io_setup(), it's not used for
113 * anything but counting against the global max_reqs quota.
115 * The real limit is nr_events - 1, which will be larger (see
120 /* Size of ringbuffer, in units of struct io_event */
123 unsigned long mmap_base
;
124 unsigned long mmap_size
;
126 struct page
**ring_pages
;
129 struct rcu_work free_rwork
; /* see free_ioctx() */
132 * signals when all in-flight requests are done
134 struct ctx_rq_wait
*rq_wait
;
138 * This counts the number of available slots in the ringbuffer,
139 * so we avoid overflowing it: it's decremented (if positive)
140 * when allocating a kiocb and incremented when the resulting
141 * io_event is pulled off the ringbuffer.
143 * We batch accesses to it with a percpu version.
145 atomic_t reqs_available
;
146 } ____cacheline_aligned_in_smp
;
150 struct list_head active_reqs
; /* used for cancellation */
151 } ____cacheline_aligned_in_smp
;
154 struct mutex ring_lock
;
155 wait_queue_head_t wait
;
156 } ____cacheline_aligned_in_smp
;
160 unsigned completed_events
;
161 spinlock_t completion_lock
;
162 } ____cacheline_aligned_in_smp
;
164 struct page
*internal_pages
[AIO_RING_PAGES
];
165 struct file
*aio_ring_file
;
171 * First field must be the file pointer in all the
172 * iocb unions! See also 'struct kiocb' in <linux/fs.h>
176 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 iocb __user
*ki_user_iocb
; /* user's aiocb */
208 __u64 ki_user_data
; /* user's data for completion */
210 struct list_head ki_list
; /* the aio core uses this
211 * for cancellation */
212 refcount_t ki_refcnt
;
215 * If the aio_resfd field of the userspace iocb is not zero,
216 * this is the underlying eventfd context to deliver events to.
218 struct eventfd_ctx
*ki_eventfd
;
221 /*------ sysctl variables----*/
222 static DEFINE_SPINLOCK(aio_nr_lock
);
223 unsigned long aio_nr
; /* current system wide number of aio requests */
224 unsigned long aio_max_nr
= 0x10000; /* system wide maximum number of aio requests */
225 /*----end sysctl variables---*/
227 static struct kmem_cache
*kiocb_cachep
;
228 static struct kmem_cache
*kioctx_cachep
;
230 static struct vfsmount
*aio_mnt
;
232 static const struct file_operations aio_ring_fops
;
233 static const struct address_space_operations aio_ctx_aops
;
235 static struct file
*aio_private_file(struct kioctx
*ctx
, loff_t nr_pages
)
238 struct inode
*inode
= alloc_anon_inode(aio_mnt
->mnt_sb
);
240 return ERR_CAST(inode
);
242 inode
->i_mapping
->a_ops
= &aio_ctx_aops
;
243 inode
->i_mapping
->private_data
= ctx
;
244 inode
->i_size
= PAGE_SIZE
* nr_pages
;
246 file
= alloc_file_pseudo(inode
, aio_mnt
, "[aio]",
247 O_RDWR
, &aio_ring_fops
);
253 static struct dentry
*aio_mount(struct file_system_type
*fs_type
,
254 int flags
, const char *dev_name
, void *data
)
256 struct dentry
*root
= mount_pseudo(fs_type
, "aio:", NULL
, NULL
,
260 root
->d_sb
->s_iflags
|= SB_I_NOEXEC
;
265 * Creates the slab caches used by the aio routines, panic on
266 * failure as this is done early during the boot sequence.
268 static int __init
aio_setup(void)
270 static struct file_system_type aio_fs
= {
273 .kill_sb
= kill_anon_super
,
275 aio_mnt
= kern_mount(&aio_fs
);
277 panic("Failed to create aio fs mount.");
279 kiocb_cachep
= KMEM_CACHE(aio_kiocb
, SLAB_HWCACHE_ALIGN
|SLAB_PANIC
);
280 kioctx_cachep
= KMEM_CACHE(kioctx
,SLAB_HWCACHE_ALIGN
|SLAB_PANIC
);
283 __initcall(aio_setup
);
285 static void put_aio_ring_file(struct kioctx
*ctx
)
287 struct file
*aio_ring_file
= ctx
->aio_ring_file
;
288 struct address_space
*i_mapping
;
291 truncate_setsize(file_inode(aio_ring_file
), 0);
293 /* Prevent further access to the kioctx from migratepages */
294 i_mapping
= aio_ring_file
->f_mapping
;
295 spin_lock(&i_mapping
->private_lock
);
296 i_mapping
->private_data
= NULL
;
297 ctx
->aio_ring_file
= NULL
;
298 spin_unlock(&i_mapping
->private_lock
);
304 static void aio_free_ring(struct kioctx
*ctx
)
308 /* Disconnect the kiotx from the ring file. This prevents future
309 * accesses to the kioctx from page migration.
311 put_aio_ring_file(ctx
);
313 for (i
= 0; i
< ctx
->nr_pages
; i
++) {
315 pr_debug("pid(%d) [%d] page->count=%d\n", current
->pid
, i
,
316 page_count(ctx
->ring_pages
[i
]));
317 page
= ctx
->ring_pages
[i
];
320 ctx
->ring_pages
[i
] = NULL
;
324 if (ctx
->ring_pages
&& ctx
->ring_pages
!= ctx
->internal_pages
) {
325 kfree(ctx
->ring_pages
);
326 ctx
->ring_pages
= NULL
;
330 static int aio_ring_mremap(struct vm_area_struct
*vma
)
332 struct file
*file
= vma
->vm_file
;
333 struct mm_struct
*mm
= vma
->vm_mm
;
334 struct kioctx_table
*table
;
335 int i
, res
= -EINVAL
;
337 spin_lock(&mm
->ioctx_lock
);
339 table
= rcu_dereference(mm
->ioctx_table
);
340 for (i
= 0; i
< table
->nr
; i
++) {
343 ctx
= rcu_dereference(table
->table
[i
]);
344 if (ctx
&& ctx
->aio_ring_file
== file
) {
345 if (!atomic_read(&ctx
->dead
)) {
346 ctx
->user_id
= ctx
->mmap_base
= vma
->vm_start
;
354 spin_unlock(&mm
->ioctx_lock
);
358 static const struct vm_operations_struct aio_ring_vm_ops
= {
359 .mremap
= aio_ring_mremap
,
360 #if IS_ENABLED(CONFIG_MMU)
361 .fault
= filemap_fault
,
362 .map_pages
= filemap_map_pages
,
363 .page_mkwrite
= filemap_page_mkwrite
,
367 static int aio_ring_mmap(struct file
*file
, struct vm_area_struct
*vma
)
369 vma
->vm_flags
|= VM_DONTEXPAND
;
370 vma
->vm_ops
= &aio_ring_vm_ops
;
374 static const struct file_operations aio_ring_fops
= {
375 .mmap
= aio_ring_mmap
,
378 #if IS_ENABLED(CONFIG_MIGRATION)
379 static int aio_migratepage(struct address_space
*mapping
, struct page
*new,
380 struct page
*old
, enum migrate_mode mode
)
388 * We cannot support the _NO_COPY case here, because copy needs to
389 * happen under the ctx->completion_lock. That does not work with the
390 * migration workflow of MIGRATE_SYNC_NO_COPY.
392 if (mode
== MIGRATE_SYNC_NO_COPY
)
397 /* mapping->private_lock here protects against the kioctx teardown. */
398 spin_lock(&mapping
->private_lock
);
399 ctx
= mapping
->private_data
;
405 /* The ring_lock mutex. The prevents aio_read_events() from writing
406 * to the ring's head, and prevents page migration from mucking in
407 * a partially initialized kiotx.
409 if (!mutex_trylock(&ctx
->ring_lock
)) {
415 if (idx
< (pgoff_t
)ctx
->nr_pages
) {
416 /* Make sure the old page hasn't already been changed */
417 if (ctx
->ring_pages
[idx
] != old
)
425 /* Writeback must be complete */
426 BUG_ON(PageWriteback(old
));
429 rc
= migrate_page_move_mapping(mapping
, new, old
, mode
, 1);
430 if (rc
!= MIGRATEPAGE_SUCCESS
) {
435 /* Take completion_lock to prevent other writes to the ring buffer
436 * while the old page is copied to the new. This prevents new
437 * events from being lost.
439 spin_lock_irqsave(&ctx
->completion_lock
, flags
);
440 migrate_page_copy(new, old
);
441 BUG_ON(ctx
->ring_pages
[idx
] != old
);
442 ctx
->ring_pages
[idx
] = new;
443 spin_unlock_irqrestore(&ctx
->completion_lock
, flags
);
445 /* The old page is no longer accessible. */
449 mutex_unlock(&ctx
->ring_lock
);
451 spin_unlock(&mapping
->private_lock
);
456 static const struct address_space_operations aio_ctx_aops
= {
457 .set_page_dirty
= __set_page_dirty_no_writeback
,
458 #if IS_ENABLED(CONFIG_MIGRATION)
459 .migratepage
= aio_migratepage
,
463 static int aio_setup_ring(struct kioctx
*ctx
, unsigned int nr_events
)
465 struct aio_ring
*ring
;
466 struct mm_struct
*mm
= current
->mm
;
467 unsigned long size
, unused
;
472 /* Compensate for the ring buffer's head/tail overlap entry */
473 nr_events
+= 2; /* 1 is required, 2 for good luck */
475 size
= sizeof(struct aio_ring
);
476 size
+= sizeof(struct io_event
) * nr_events
;
478 nr_pages
= PFN_UP(size
);
482 file
= aio_private_file(ctx
, nr_pages
);
484 ctx
->aio_ring_file
= NULL
;
488 ctx
->aio_ring_file
= file
;
489 nr_events
= (PAGE_SIZE
* nr_pages
- sizeof(struct aio_ring
))
490 / sizeof(struct io_event
);
492 ctx
->ring_pages
= ctx
->internal_pages
;
493 if (nr_pages
> AIO_RING_PAGES
) {
494 ctx
->ring_pages
= kcalloc(nr_pages
, sizeof(struct page
*),
496 if (!ctx
->ring_pages
) {
497 put_aio_ring_file(ctx
);
502 for (i
= 0; i
< nr_pages
; i
++) {
504 page
= find_or_create_page(file
->f_mapping
,
505 i
, GFP_HIGHUSER
| __GFP_ZERO
);
508 pr_debug("pid(%d) page[%d]->count=%d\n",
509 current
->pid
, i
, page_count(page
));
510 SetPageUptodate(page
);
513 ctx
->ring_pages
[i
] = page
;
517 if (unlikely(i
!= nr_pages
)) {
522 ctx
->mmap_size
= nr_pages
* PAGE_SIZE
;
523 pr_debug("attempting mmap of %lu bytes\n", ctx
->mmap_size
);
525 if (down_write_killable(&mm
->mmap_sem
)) {
531 ctx
->mmap_base
= do_mmap_pgoff(ctx
->aio_ring_file
, 0, ctx
->mmap_size
,
532 PROT_READ
| PROT_WRITE
,
533 MAP_SHARED
, 0, &unused
, NULL
);
534 up_write(&mm
->mmap_sem
);
535 if (IS_ERR((void *)ctx
->mmap_base
)) {
541 pr_debug("mmap address: 0x%08lx\n", ctx
->mmap_base
);
543 ctx
->user_id
= ctx
->mmap_base
;
544 ctx
->nr_events
= nr_events
; /* trusted copy */
546 ring
= kmap_atomic(ctx
->ring_pages
[0]);
547 ring
->nr
= nr_events
; /* user copy */
549 ring
->head
= ring
->tail
= 0;
550 ring
->magic
= AIO_RING_MAGIC
;
551 ring
->compat_features
= AIO_RING_COMPAT_FEATURES
;
552 ring
->incompat_features
= AIO_RING_INCOMPAT_FEATURES
;
553 ring
->header_length
= sizeof(struct aio_ring
);
555 flush_dcache_page(ctx
->ring_pages
[0]);
560 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
561 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
562 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
564 void kiocb_set_cancel_fn(struct kiocb
*iocb
, kiocb_cancel_fn
*cancel
)
566 struct aio_kiocb
*req
= container_of(iocb
, struct aio_kiocb
, rw
);
567 struct kioctx
*ctx
= req
->ki_ctx
;
570 if (WARN_ON_ONCE(!list_empty(&req
->ki_list
)))
573 spin_lock_irqsave(&ctx
->ctx_lock
, flags
);
574 list_add_tail(&req
->ki_list
, &ctx
->active_reqs
);
575 req
->ki_cancel
= cancel
;
576 spin_unlock_irqrestore(&ctx
->ctx_lock
, flags
);
578 EXPORT_SYMBOL(kiocb_set_cancel_fn
);
581 * free_ioctx() should be RCU delayed to synchronize against the RCU
582 * protected lookup_ioctx() and also needs process context to call
583 * aio_free_ring(). Use rcu_work.
585 static void free_ioctx(struct work_struct
*work
)
587 struct kioctx
*ctx
= container_of(to_rcu_work(work
), struct kioctx
,
589 pr_debug("freeing %p\n", ctx
);
592 free_percpu(ctx
->cpu
);
593 percpu_ref_exit(&ctx
->reqs
);
594 percpu_ref_exit(&ctx
->users
);
595 kmem_cache_free(kioctx_cachep
, ctx
);
598 static void free_ioctx_reqs(struct percpu_ref
*ref
)
600 struct kioctx
*ctx
= container_of(ref
, struct kioctx
, reqs
);
602 /* At this point we know that there are no any in-flight requests */
603 if (ctx
->rq_wait
&& atomic_dec_and_test(&ctx
->rq_wait
->count
))
604 complete(&ctx
->rq_wait
->comp
);
606 /* Synchronize against RCU protected table->table[] dereferences */
607 INIT_RCU_WORK(&ctx
->free_rwork
, free_ioctx
);
608 queue_rcu_work(system_wq
, &ctx
->free_rwork
);
612 * When this function runs, the kioctx has been removed from the "hash table"
613 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
614 * now it's safe to cancel any that need to be.
616 static void free_ioctx_users(struct percpu_ref
*ref
)
618 struct kioctx
*ctx
= container_of(ref
, struct kioctx
, users
);
619 struct aio_kiocb
*req
;
621 spin_lock_irq(&ctx
->ctx_lock
);
623 while (!list_empty(&ctx
->active_reqs
)) {
624 req
= list_first_entry(&ctx
->active_reqs
,
625 struct aio_kiocb
, ki_list
);
626 req
->ki_cancel(&req
->rw
);
627 list_del_init(&req
->ki_list
);
630 spin_unlock_irq(&ctx
->ctx_lock
);
632 percpu_ref_kill(&ctx
->reqs
);
633 percpu_ref_put(&ctx
->reqs
);
636 static int ioctx_add_table(struct kioctx
*ctx
, struct mm_struct
*mm
)
639 struct kioctx_table
*table
, *old
;
640 struct aio_ring
*ring
;
642 spin_lock(&mm
->ioctx_lock
);
643 table
= rcu_dereference_raw(mm
->ioctx_table
);
647 for (i
= 0; i
< table
->nr
; i
++)
648 if (!rcu_access_pointer(table
->table
[i
])) {
650 rcu_assign_pointer(table
->table
[i
], ctx
);
651 spin_unlock(&mm
->ioctx_lock
);
653 /* While kioctx setup is in progress,
654 * we are protected from page migration
655 * changes ring_pages by ->ring_lock.
657 ring
= kmap_atomic(ctx
->ring_pages
[0]);
663 new_nr
= (table
? table
->nr
: 1) * 4;
664 spin_unlock(&mm
->ioctx_lock
);
666 table
= kzalloc(sizeof(*table
) + sizeof(struct kioctx
*) *
673 spin_lock(&mm
->ioctx_lock
);
674 old
= rcu_dereference_raw(mm
->ioctx_table
);
677 rcu_assign_pointer(mm
->ioctx_table
, table
);
678 } else if (table
->nr
> old
->nr
) {
679 memcpy(table
->table
, old
->table
,
680 old
->nr
* sizeof(struct kioctx
*));
682 rcu_assign_pointer(mm
->ioctx_table
, table
);
691 static void aio_nr_sub(unsigned nr
)
693 spin_lock(&aio_nr_lock
);
694 if (WARN_ON(aio_nr
- nr
> aio_nr
))
698 spin_unlock(&aio_nr_lock
);
702 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
704 static struct kioctx
*ioctx_alloc(unsigned nr_events
)
706 struct mm_struct
*mm
= current
->mm
;
711 * Store the original nr_events -- what userspace passed to io_setup(),
712 * for counting against the global limit -- before it changes.
714 unsigned int max_reqs
= nr_events
;
717 * We keep track of the number of available ringbuffer slots, to prevent
718 * overflow (reqs_available), and we also use percpu counters for this.
720 * So since up to half the slots might be on other cpu's percpu counters
721 * and unavailable, double nr_events so userspace sees what they
722 * expected: additionally, we move req_batch slots to/from percpu
723 * counters at a time, so make sure that isn't 0:
725 nr_events
= max(nr_events
, num_possible_cpus() * 4);
728 /* Prevent overflows */
729 if (nr_events
> (0x10000000U
/ sizeof(struct io_event
))) {
730 pr_debug("ENOMEM: nr_events too high\n");
731 return ERR_PTR(-EINVAL
);
734 if (!nr_events
|| (unsigned long)max_reqs
> aio_max_nr
)
735 return ERR_PTR(-EAGAIN
);
737 ctx
= kmem_cache_zalloc(kioctx_cachep
, GFP_KERNEL
);
739 return ERR_PTR(-ENOMEM
);
741 ctx
->max_reqs
= max_reqs
;
743 spin_lock_init(&ctx
->ctx_lock
);
744 spin_lock_init(&ctx
->completion_lock
);
745 mutex_init(&ctx
->ring_lock
);
746 /* Protect against page migration throughout kiotx setup by keeping
747 * the ring_lock mutex held until setup is complete. */
748 mutex_lock(&ctx
->ring_lock
);
749 init_waitqueue_head(&ctx
->wait
);
751 INIT_LIST_HEAD(&ctx
->active_reqs
);
753 if (percpu_ref_init(&ctx
->users
, free_ioctx_users
, 0, GFP_KERNEL
))
756 if (percpu_ref_init(&ctx
->reqs
, free_ioctx_reqs
, 0, GFP_KERNEL
))
759 ctx
->cpu
= alloc_percpu(struct kioctx_cpu
);
763 err
= aio_setup_ring(ctx
, nr_events
);
767 atomic_set(&ctx
->reqs_available
, ctx
->nr_events
- 1);
768 ctx
->req_batch
= (ctx
->nr_events
- 1) / (num_possible_cpus() * 4);
769 if (ctx
->req_batch
< 1)
772 /* limit the number of system wide aios */
773 spin_lock(&aio_nr_lock
);
774 if (aio_nr
+ ctx
->max_reqs
> aio_max_nr
||
775 aio_nr
+ ctx
->max_reqs
< aio_nr
) {
776 spin_unlock(&aio_nr_lock
);
780 aio_nr
+= ctx
->max_reqs
;
781 spin_unlock(&aio_nr_lock
);
783 percpu_ref_get(&ctx
->users
); /* io_setup() will drop this ref */
784 percpu_ref_get(&ctx
->reqs
); /* free_ioctx_users() will drop this */
786 err
= ioctx_add_table(ctx
, mm
);
790 /* Release the ring_lock mutex now that all setup is complete. */
791 mutex_unlock(&ctx
->ring_lock
);
793 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
794 ctx
, ctx
->user_id
, mm
, ctx
->nr_events
);
798 aio_nr_sub(ctx
->max_reqs
);
800 atomic_set(&ctx
->dead
, 1);
802 vm_munmap(ctx
->mmap_base
, ctx
->mmap_size
);
805 mutex_unlock(&ctx
->ring_lock
);
806 free_percpu(ctx
->cpu
);
807 percpu_ref_exit(&ctx
->reqs
);
808 percpu_ref_exit(&ctx
->users
);
809 kmem_cache_free(kioctx_cachep
, ctx
);
810 pr_debug("error allocating ioctx %d\n", err
);
815 * Cancels all outstanding aio requests on an aio context. Used
816 * when the processes owning a context have all exited to encourage
817 * the rapid destruction of the kioctx.
819 static int kill_ioctx(struct mm_struct
*mm
, struct kioctx
*ctx
,
820 struct ctx_rq_wait
*wait
)
822 struct kioctx_table
*table
;
824 spin_lock(&mm
->ioctx_lock
);
825 if (atomic_xchg(&ctx
->dead
, 1)) {
826 spin_unlock(&mm
->ioctx_lock
);
830 table
= rcu_dereference_raw(mm
->ioctx_table
);
831 WARN_ON(ctx
!= rcu_access_pointer(table
->table
[ctx
->id
]));
832 RCU_INIT_POINTER(table
->table
[ctx
->id
], NULL
);
833 spin_unlock(&mm
->ioctx_lock
);
835 /* free_ioctx_reqs() will do the necessary RCU synchronization */
836 wake_up_all(&ctx
->wait
);
839 * It'd be more correct to do this in free_ioctx(), after all
840 * the outstanding kiocbs have finished - but by then io_destroy
841 * has already returned, so io_setup() could potentially return
842 * -EAGAIN with no ioctxs actually in use (as far as userspace
845 aio_nr_sub(ctx
->max_reqs
);
848 vm_munmap(ctx
->mmap_base
, ctx
->mmap_size
);
851 percpu_ref_kill(&ctx
->users
);
856 * exit_aio: called when the last user of mm goes away. At this point, there is
857 * no way for any new requests to be submited or any of the io_* syscalls to be
858 * called on the context.
860 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
863 void exit_aio(struct mm_struct
*mm
)
865 struct kioctx_table
*table
= rcu_dereference_raw(mm
->ioctx_table
);
866 struct ctx_rq_wait wait
;
872 atomic_set(&wait
.count
, table
->nr
);
873 init_completion(&wait
.comp
);
876 for (i
= 0; i
< table
->nr
; ++i
) {
878 rcu_dereference_protected(table
->table
[i
], true);
886 * We don't need to bother with munmap() here - exit_mmap(mm)
887 * is coming and it'll unmap everything. And we simply can't,
888 * this is not necessarily our ->mm.
889 * Since kill_ioctx() uses non-zero ->mmap_size as indicator
890 * that it needs to unmap the area, just set it to 0.
893 kill_ioctx(mm
, ctx
, &wait
);
896 if (!atomic_sub_and_test(skipped
, &wait
.count
)) {
897 /* Wait until all IO for the context are done. */
898 wait_for_completion(&wait
.comp
);
901 RCU_INIT_POINTER(mm
->ioctx_table
, NULL
);
905 static void put_reqs_available(struct kioctx
*ctx
, unsigned nr
)
907 struct kioctx_cpu
*kcpu
;
910 local_irq_save(flags
);
911 kcpu
= this_cpu_ptr(ctx
->cpu
);
912 kcpu
->reqs_available
+= nr
;
914 while (kcpu
->reqs_available
>= ctx
->req_batch
* 2) {
915 kcpu
->reqs_available
-= ctx
->req_batch
;
916 atomic_add(ctx
->req_batch
, &ctx
->reqs_available
);
919 local_irq_restore(flags
);
922 static bool __get_reqs_available(struct kioctx
*ctx
)
924 struct kioctx_cpu
*kcpu
;
928 local_irq_save(flags
);
929 kcpu
= this_cpu_ptr(ctx
->cpu
);
930 if (!kcpu
->reqs_available
) {
931 int old
, avail
= atomic_read(&ctx
->reqs_available
);
934 if (avail
< ctx
->req_batch
)
938 avail
= atomic_cmpxchg(&ctx
->reqs_available
,
939 avail
, avail
- ctx
->req_batch
);
940 } while (avail
!= old
);
942 kcpu
->reqs_available
+= ctx
->req_batch
;
946 kcpu
->reqs_available
--;
948 local_irq_restore(flags
);
952 /* refill_reqs_available
953 * Updates the reqs_available reference counts used for tracking the
954 * number of free slots in the completion ring. This can be called
955 * from aio_complete() (to optimistically update reqs_available) or
956 * from aio_get_req() (the we're out of events case). It must be
957 * called holding ctx->completion_lock.
959 static void refill_reqs_available(struct kioctx
*ctx
, unsigned head
,
962 unsigned events_in_ring
, completed
;
964 /* Clamp head since userland can write to it. */
965 head
%= ctx
->nr_events
;
967 events_in_ring
= tail
- head
;
969 events_in_ring
= ctx
->nr_events
- (head
- tail
);
971 completed
= ctx
->completed_events
;
972 if (events_in_ring
< completed
)
973 completed
-= events_in_ring
;
980 ctx
->completed_events
-= completed
;
981 put_reqs_available(ctx
, completed
);
984 /* user_refill_reqs_available
985 * Called to refill reqs_available when aio_get_req() encounters an
986 * out of space in the completion ring.
988 static void user_refill_reqs_available(struct kioctx
*ctx
)
990 spin_lock_irq(&ctx
->completion_lock
);
991 if (ctx
->completed_events
) {
992 struct aio_ring
*ring
;
995 /* Access of ring->head may race with aio_read_events_ring()
996 * here, but that's okay since whether we read the old version
997 * or the new version, and either will be valid. The important
998 * part is that head cannot pass tail since we prevent
999 * aio_complete() from updating tail by holding
1000 * ctx->completion_lock. Even if head is invalid, the check
1001 * against ctx->completed_events below will make sure we do the
1004 ring
= kmap_atomic(ctx
->ring_pages
[0]);
1006 kunmap_atomic(ring
);
1008 refill_reqs_available(ctx
, head
, ctx
->tail
);
1011 spin_unlock_irq(&ctx
->completion_lock
);
1014 static bool get_reqs_available(struct kioctx
*ctx
)
1016 if (__get_reqs_available(ctx
))
1018 user_refill_reqs_available(ctx
);
1019 return __get_reqs_available(ctx
);
1023 * Allocate a slot for an aio request.
1024 * Returns NULL if no requests are free.
1026 static inline struct aio_kiocb
*aio_get_req(struct kioctx
*ctx
)
1028 struct aio_kiocb
*req
;
1030 req
= kmem_cache_alloc(kiocb_cachep
, GFP_KERNEL
);
1034 percpu_ref_get(&ctx
->reqs
);
1036 INIT_LIST_HEAD(&req
->ki_list
);
1037 refcount_set(&req
->ki_refcnt
, 0);
1038 req
->ki_eventfd
= NULL
;
1042 static struct kioctx
*lookup_ioctx(unsigned long ctx_id
)
1044 struct aio_ring __user
*ring
= (void __user
*)ctx_id
;
1045 struct mm_struct
*mm
= current
->mm
;
1046 struct kioctx
*ctx
, *ret
= NULL
;
1047 struct kioctx_table
*table
;
1050 if (get_user(id
, &ring
->id
))
1054 table
= rcu_dereference(mm
->ioctx_table
);
1056 if (!table
|| id
>= table
->nr
)
1059 id
= array_index_nospec(id
, table
->nr
);
1060 ctx
= rcu_dereference(table
->table
[id
]);
1061 if (ctx
&& ctx
->user_id
== ctx_id
) {
1062 if (percpu_ref_tryget_live(&ctx
->users
))
1070 static inline void iocb_put(struct aio_kiocb
*iocb
)
1072 if (refcount_read(&iocb
->ki_refcnt
) == 0 ||
1073 refcount_dec_and_test(&iocb
->ki_refcnt
)) {
1075 fput(iocb
->ki_filp
);
1076 percpu_ref_put(&iocb
->ki_ctx
->reqs
);
1077 kmem_cache_free(kiocb_cachep
, iocb
);
1081 static void aio_fill_event(struct io_event
*ev
, struct aio_kiocb
*iocb
,
1082 long res
, long res2
)
1084 ev
->obj
= (u64
)(unsigned long)iocb
->ki_user_iocb
;
1085 ev
->data
= iocb
->ki_user_data
;
1091 * Called when the io request on the given iocb is complete.
1093 static void aio_complete(struct aio_kiocb
*iocb
, long res
, long res2
)
1095 struct kioctx
*ctx
= iocb
->ki_ctx
;
1096 struct aio_ring
*ring
;
1097 struct io_event
*ev_page
, *event
;
1098 unsigned tail
, pos
, head
;
1099 unsigned long flags
;
1102 * Add a completion event to the ring buffer. Must be done holding
1103 * ctx->completion_lock to prevent other code from messing with the tail
1104 * pointer since we might be called from irq context.
1106 spin_lock_irqsave(&ctx
->completion_lock
, flags
);
1109 pos
= tail
+ AIO_EVENTS_OFFSET
;
1111 if (++tail
>= ctx
->nr_events
)
1114 ev_page
= kmap_atomic(ctx
->ring_pages
[pos
/ AIO_EVENTS_PER_PAGE
]);
1115 event
= ev_page
+ pos
% AIO_EVENTS_PER_PAGE
;
1117 aio_fill_event(event
, iocb
, res
, res2
);
1119 kunmap_atomic(ev_page
);
1120 flush_dcache_page(ctx
->ring_pages
[pos
/ AIO_EVENTS_PER_PAGE
]);
1122 pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
1123 ctx
, tail
, iocb
, iocb
->ki_user_iocb
, iocb
->ki_user_data
,
1126 /* after flagging the request as done, we
1127 * must never even look at it again
1129 smp_wmb(); /* make event visible before updating tail */
1133 ring
= kmap_atomic(ctx
->ring_pages
[0]);
1136 kunmap_atomic(ring
);
1137 flush_dcache_page(ctx
->ring_pages
[0]);
1139 ctx
->completed_events
++;
1140 if (ctx
->completed_events
> 1)
1141 refill_reqs_available(ctx
, head
, tail
);
1142 spin_unlock_irqrestore(&ctx
->completion_lock
, flags
);
1144 pr_debug("added to ring %p at [%u]\n", iocb
, tail
);
1147 * Check if the user asked us to deliver the result through an
1148 * eventfd. The eventfd_signal() function is safe to be called
1151 if (iocb
->ki_eventfd
) {
1152 eventfd_signal(iocb
->ki_eventfd
, 1);
1153 eventfd_ctx_put(iocb
->ki_eventfd
);
1157 * We have to order our ring_info tail store above and test
1158 * of the wait list below outside the wait lock. This is
1159 * like in wake_up_bit() where clearing a bit has to be
1160 * ordered with the unlocked test.
1164 if (waitqueue_active(&ctx
->wait
))
1165 wake_up(&ctx
->wait
);
1169 /* aio_read_events_ring
1170 * Pull an event off of the ioctx's event ring. Returns the number of
1173 static long aio_read_events_ring(struct kioctx
*ctx
,
1174 struct io_event __user
*event
, long nr
)
1176 struct aio_ring
*ring
;
1177 unsigned head
, tail
, pos
;
1182 * The mutex can block and wake us up and that will cause
1183 * wait_event_interruptible_hrtimeout() to schedule without sleeping
1184 * and repeat. This should be rare enough that it doesn't cause
1185 * peformance issues. See the comment in read_events() for more detail.
1187 sched_annotate_sleep();
1188 mutex_lock(&ctx
->ring_lock
);
1190 /* Access to ->ring_pages here is protected by ctx->ring_lock. */
1191 ring
= kmap_atomic(ctx
->ring_pages
[0]);
1194 kunmap_atomic(ring
);
1197 * Ensure that once we've read the current tail pointer, that
1198 * we also see the events that were stored up to the tail.
1202 pr_debug("h%u t%u m%u\n", head
, tail
, ctx
->nr_events
);
1207 head
%= ctx
->nr_events
;
1208 tail
%= ctx
->nr_events
;
1212 struct io_event
*ev
;
1215 avail
= (head
<= tail
? tail
: ctx
->nr_events
) - head
;
1219 pos
= head
+ AIO_EVENTS_OFFSET
;
1220 page
= ctx
->ring_pages
[pos
/ AIO_EVENTS_PER_PAGE
];
1221 pos
%= AIO_EVENTS_PER_PAGE
;
1223 avail
= min(avail
, nr
- ret
);
1224 avail
= min_t(long, avail
, AIO_EVENTS_PER_PAGE
- pos
);
1227 copy_ret
= copy_to_user(event
+ ret
, ev
+ pos
,
1228 sizeof(*ev
) * avail
);
1231 if (unlikely(copy_ret
)) {
1238 head
%= ctx
->nr_events
;
1241 ring
= kmap_atomic(ctx
->ring_pages
[0]);
1243 kunmap_atomic(ring
);
1244 flush_dcache_page(ctx
->ring_pages
[0]);
1246 pr_debug("%li h%u t%u\n", ret
, head
, tail
);
1248 mutex_unlock(&ctx
->ring_lock
);
1253 static bool aio_read_events(struct kioctx
*ctx
, long min_nr
, long nr
,
1254 struct io_event __user
*event
, long *i
)
1256 long ret
= aio_read_events_ring(ctx
, event
+ *i
, nr
- *i
);
1261 if (unlikely(atomic_read(&ctx
->dead
)))
1267 return ret
< 0 || *i
>= min_nr
;
1270 static long read_events(struct kioctx
*ctx
, long min_nr
, long nr
,
1271 struct io_event __user
*event
,
1277 * Note that aio_read_events() is being called as the conditional - i.e.
1278 * we're calling it after prepare_to_wait() has set task state to
1279 * TASK_INTERRUPTIBLE.
1281 * But aio_read_events() can block, and if it blocks it's going to flip
1282 * the task state back to TASK_RUNNING.
1284 * This should be ok, provided it doesn't flip the state back to
1285 * TASK_RUNNING and return 0 too much - that causes us to spin. That
1286 * will only happen if the mutex_lock() call blocks, and we then find
1287 * the ringbuffer empty. So in practice we should be ok, but it's
1288 * something to be aware of when touching this code.
1291 aio_read_events(ctx
, min_nr
, nr
, event
, &ret
);
1293 wait_event_interruptible_hrtimeout(ctx
->wait
,
1294 aio_read_events(ctx
, min_nr
, nr
, event
, &ret
),
1300 * Create an aio_context capable of receiving at least nr_events.
1301 * ctxp must not point to an aio_context that already exists, and
1302 * must be initialized to 0 prior to the call. On successful
1303 * creation of the aio_context, *ctxp is filled in with the resulting
1304 * handle. May fail with -EINVAL if *ctxp is not initialized,
1305 * if the specified nr_events exceeds internal limits. May fail
1306 * with -EAGAIN if the specified nr_events exceeds the user's limit
1307 * of available events. May fail with -ENOMEM if insufficient kernel
1308 * resources are available. May fail with -EFAULT if an invalid
1309 * pointer is passed for ctxp. Will fail with -ENOSYS if not
1312 SYSCALL_DEFINE2(io_setup
, unsigned, nr_events
, aio_context_t __user
*, ctxp
)
1314 struct kioctx
*ioctx
= NULL
;
1318 ret
= get_user(ctx
, ctxp
);
1323 if (unlikely(ctx
|| nr_events
== 0)) {
1324 pr_debug("EINVAL: ctx %lu nr_events %u\n",
1329 ioctx
= ioctx_alloc(nr_events
);
1330 ret
= PTR_ERR(ioctx
);
1331 if (!IS_ERR(ioctx
)) {
1332 ret
= put_user(ioctx
->user_id
, ctxp
);
1334 kill_ioctx(current
->mm
, ioctx
, NULL
);
1335 percpu_ref_put(&ioctx
->users
);
1342 #ifdef CONFIG_COMPAT
1343 COMPAT_SYSCALL_DEFINE2(io_setup
, unsigned, nr_events
, u32 __user
*, ctx32p
)
1345 struct kioctx
*ioctx
= NULL
;
1349 ret
= get_user(ctx
, ctx32p
);
1354 if (unlikely(ctx
|| nr_events
== 0)) {
1355 pr_debug("EINVAL: ctx %lu nr_events %u\n",
1360 ioctx
= ioctx_alloc(nr_events
);
1361 ret
= PTR_ERR(ioctx
);
1362 if (!IS_ERR(ioctx
)) {
1363 /* truncating is ok because it's a user address */
1364 ret
= put_user((u32
)ioctx
->user_id
, ctx32p
);
1366 kill_ioctx(current
->mm
, ioctx
, NULL
);
1367 percpu_ref_put(&ioctx
->users
);
1376 * Destroy the aio_context specified. May cancel any outstanding
1377 * AIOs and block on completion. Will fail with -ENOSYS if not
1378 * implemented. May fail with -EINVAL if the context pointed to
1381 SYSCALL_DEFINE1(io_destroy
, aio_context_t
, ctx
)
1383 struct kioctx
*ioctx
= lookup_ioctx(ctx
);
1384 if (likely(NULL
!= ioctx
)) {
1385 struct ctx_rq_wait wait
;
1388 init_completion(&wait
.comp
);
1389 atomic_set(&wait
.count
, 1);
1391 /* Pass requests_done to kill_ioctx() where it can be set
1392 * in a thread-safe way. If we try to set it here then we have
1393 * a race condition if two io_destroy() called simultaneously.
1395 ret
= kill_ioctx(current
->mm
, ioctx
, &wait
);
1396 percpu_ref_put(&ioctx
->users
);
1398 /* Wait until all IO for the context are done. Otherwise kernel
1399 * keep using user-space buffers even if user thinks the context
1403 wait_for_completion(&wait
.comp
);
1407 pr_debug("EINVAL: invalid context id\n");
1411 static void aio_remove_iocb(struct aio_kiocb
*iocb
)
1413 struct kioctx
*ctx
= iocb
->ki_ctx
;
1414 unsigned long flags
;
1416 spin_lock_irqsave(&ctx
->ctx_lock
, flags
);
1417 list_del(&iocb
->ki_list
);
1418 spin_unlock_irqrestore(&ctx
->ctx_lock
, flags
);
1421 static void aio_complete_rw(struct kiocb
*kiocb
, long res
, long res2
)
1423 struct aio_kiocb
*iocb
= container_of(kiocb
, struct aio_kiocb
, rw
);
1425 if (!list_empty_careful(&iocb
->ki_list
))
1426 aio_remove_iocb(iocb
);
1428 if (kiocb
->ki_flags
& IOCB_WRITE
) {
1429 struct inode
*inode
= file_inode(kiocb
->ki_filp
);
1432 * Tell lockdep we inherited freeze protection from submission
1435 if (S_ISREG(inode
->i_mode
))
1436 __sb_writers_acquired(inode
->i_sb
, SB_FREEZE_WRITE
);
1437 file_end_write(kiocb
->ki_filp
);
1440 aio_complete(iocb
, res
, res2
);
1443 static int aio_prep_rw(struct kiocb
*req
, const struct iocb
*iocb
)
1447 req
->ki_complete
= aio_complete_rw
;
1448 req
->private = NULL
;
1449 req
->ki_pos
= iocb
->aio_offset
;
1450 req
->ki_flags
= iocb_flags(req
->ki_filp
);
1451 if (iocb
->aio_flags
& IOCB_FLAG_RESFD
)
1452 req
->ki_flags
|= IOCB_EVENTFD
;
1453 req
->ki_hint
= ki_hint_validate(file_write_hint(req
->ki_filp
));
1454 if (iocb
->aio_flags
& IOCB_FLAG_IOPRIO
) {
1456 * If the IOCB_FLAG_IOPRIO flag of aio_flags is set, then
1457 * aio_reqprio is interpreted as an I/O scheduling
1458 * class and priority.
1460 ret
= ioprio_check_cap(iocb
->aio_reqprio
);
1462 pr_debug("aio ioprio check cap error: %d\n", ret
);
1466 req
->ki_ioprio
= iocb
->aio_reqprio
;
1468 req
->ki_ioprio
= get_current_ioprio();
1470 ret
= kiocb_set_rw_flags(req
, iocb
->aio_rw_flags
);
1474 req
->ki_flags
&= ~IOCB_HIPRI
; /* no one is going to poll for this I/O */
1478 static int aio_setup_rw(int rw
, const struct iocb
*iocb
, struct iovec
**iovec
,
1479 bool vectored
, bool compat
, struct iov_iter
*iter
)
1481 void __user
*buf
= (void __user
*)(uintptr_t)iocb
->aio_buf
;
1482 size_t len
= iocb
->aio_nbytes
;
1485 ssize_t ret
= import_single_range(rw
, buf
, len
, *iovec
, iter
);
1489 #ifdef CONFIG_COMPAT
1491 return compat_import_iovec(rw
, buf
, len
, UIO_FASTIOV
, iovec
,
1494 return import_iovec(rw
, buf
, len
, UIO_FASTIOV
, iovec
, iter
);
1497 static inline void aio_rw_done(struct kiocb
*req
, ssize_t ret
)
1503 case -ERESTARTNOINTR
:
1504 case -ERESTARTNOHAND
:
1505 case -ERESTART_RESTARTBLOCK
:
1507 * There's no easy way to restart the syscall since other AIO's
1508 * may be already running. Just fail this IO with EINTR.
1513 req
->ki_complete(req
, ret
, 0);
1517 static ssize_t
aio_read(struct kiocb
*req
, const struct iocb
*iocb
,
1518 bool vectored
, bool compat
)
1520 struct iovec inline_vecs
[UIO_FASTIOV
], *iovec
= inline_vecs
;
1521 struct iov_iter iter
;
1525 ret
= aio_prep_rw(req
, iocb
);
1528 file
= req
->ki_filp
;
1529 if (unlikely(!(file
->f_mode
& FMODE_READ
)))
1532 if (unlikely(!file
->f_op
->read_iter
))
1535 ret
= aio_setup_rw(READ
, iocb
, &iovec
, vectored
, compat
, &iter
);
1538 ret
= rw_verify_area(READ
, file
, &req
->ki_pos
, iov_iter_count(&iter
));
1540 aio_rw_done(req
, call_read_iter(file
, req
, &iter
));
1545 static ssize_t
aio_write(struct kiocb
*req
, const struct iocb
*iocb
,
1546 bool vectored
, bool compat
)
1548 struct iovec inline_vecs
[UIO_FASTIOV
], *iovec
= inline_vecs
;
1549 struct iov_iter iter
;
1553 ret
= aio_prep_rw(req
, iocb
);
1556 file
= req
->ki_filp
;
1558 if (unlikely(!(file
->f_mode
& FMODE_WRITE
)))
1560 if (unlikely(!file
->f_op
->write_iter
))
1563 ret
= aio_setup_rw(WRITE
, iocb
, &iovec
, vectored
, compat
, &iter
);
1566 ret
= rw_verify_area(WRITE
, file
, &req
->ki_pos
, iov_iter_count(&iter
));
1569 * Open-code file_start_write here to grab freeze protection,
1570 * which will be released by another thread in
1571 * aio_complete_rw(). Fool lockdep by telling it the lock got
1572 * released so that it doesn't complain about the held lock when
1573 * we return to userspace.
1575 if (S_ISREG(file_inode(file
)->i_mode
)) {
1576 __sb_start_write(file_inode(file
)->i_sb
, SB_FREEZE_WRITE
, true);
1577 __sb_writers_release(file_inode(file
)->i_sb
, SB_FREEZE_WRITE
);
1579 req
->ki_flags
|= IOCB_WRITE
;
1580 aio_rw_done(req
, call_write_iter(file
, req
, &iter
));
1586 static void aio_fsync_work(struct work_struct
*work
)
1588 struct fsync_iocb
*req
= container_of(work
, struct fsync_iocb
, work
);
1591 ret
= vfs_fsync(req
->file
, req
->datasync
);
1592 aio_complete(container_of(req
, struct aio_kiocb
, fsync
), ret
, 0);
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
->datasync
= datasync
;
1606 INIT_WORK(&req
->work
, aio_fsync_work
);
1607 schedule_work(&req
->work
);
1611 static inline void aio_poll_complete(struct aio_kiocb
*iocb
, __poll_t mask
)
1613 aio_complete(iocb
, mangle_poll(mask
), 0);
1616 static void aio_poll_complete_work(struct work_struct
*work
)
1618 struct poll_iocb
*req
= container_of(work
, struct poll_iocb
, work
);
1619 struct aio_kiocb
*iocb
= container_of(req
, struct aio_kiocb
, poll
);
1620 struct poll_table_struct pt
= { ._key
= req
->events
};
1621 struct kioctx
*ctx
= iocb
->ki_ctx
;
1624 if (!READ_ONCE(req
->cancelled
))
1625 mask
= vfs_poll(req
->file
, &pt
) & req
->events
;
1628 * Note that ->ki_cancel callers also delete iocb from active_reqs after
1629 * calling ->ki_cancel. We need the ctx_lock roundtrip here to
1630 * synchronize with them. In the cancellation case the list_del_init
1631 * itself is not actually needed, but harmless so we keep it in to
1632 * avoid further branches in the fast path.
1634 spin_lock_irq(&ctx
->ctx_lock
);
1635 if (!mask
&& !READ_ONCE(req
->cancelled
)) {
1636 add_wait_queue(req
->head
, &req
->wait
);
1637 spin_unlock_irq(&ctx
->ctx_lock
);
1640 list_del_init(&iocb
->ki_list
);
1641 spin_unlock_irq(&ctx
->ctx_lock
);
1643 aio_poll_complete(iocb
, mask
);
1646 /* assumes we are called with irqs disabled */
1647 static int aio_poll_cancel(struct kiocb
*iocb
)
1649 struct aio_kiocb
*aiocb
= container_of(iocb
, struct aio_kiocb
, rw
);
1650 struct poll_iocb
*req
= &aiocb
->poll
;
1652 spin_lock(&req
->head
->lock
);
1653 WRITE_ONCE(req
->cancelled
, true);
1654 if (!list_empty(&req
->wait
.entry
)) {
1655 list_del_init(&req
->wait
.entry
);
1656 schedule_work(&aiocb
->poll
.work
);
1658 spin_unlock(&req
->head
->lock
);
1663 static int aio_poll_wake(struct wait_queue_entry
*wait
, unsigned mode
, int sync
,
1666 struct poll_iocb
*req
= container_of(wait
, struct poll_iocb
, wait
);
1667 struct aio_kiocb
*iocb
= container_of(req
, struct aio_kiocb
, poll
);
1668 __poll_t mask
= key_to_poll(key
);
1669 unsigned long flags
;
1673 /* for instances that support it check for an event match first: */
1675 if (!(mask
& req
->events
))
1679 * Try to complete the iocb inline if we can. Use
1680 * irqsave/irqrestore because not all filesystems (e.g. fuse)
1681 * call this function with IRQs disabled and because IRQs
1682 * have to be disabled before ctx_lock is obtained.
1684 if (spin_trylock_irqsave(&iocb
->ki_ctx
->ctx_lock
, flags
)) {
1685 list_del(&iocb
->ki_list
);
1686 spin_unlock_irqrestore(&iocb
->ki_ctx
->ctx_lock
, flags
);
1688 list_del_init(&req
->wait
.entry
);
1689 aio_poll_complete(iocb
, mask
);
1694 list_del_init(&req
->wait
.entry
);
1695 schedule_work(&req
->work
);
1699 struct aio_poll_table
{
1700 struct poll_table_struct pt
;
1701 struct aio_kiocb
*iocb
;
1706 aio_poll_queue_proc(struct file
*file
, struct wait_queue_head
*head
,
1707 struct poll_table_struct
*p
)
1709 struct aio_poll_table
*pt
= container_of(p
, struct aio_poll_table
, pt
);
1711 /* multiple wait queues per file are not supported */
1712 if (unlikely(pt
->iocb
->poll
.head
)) {
1713 pt
->error
= -EINVAL
;
1718 pt
->iocb
->poll
.head
= head
;
1719 add_wait_queue(head
, &pt
->iocb
->poll
.wait
);
1722 static ssize_t
aio_poll(struct aio_kiocb
*aiocb
, const struct iocb
*iocb
)
1724 struct kioctx
*ctx
= aiocb
->ki_ctx
;
1725 struct poll_iocb
*req
= &aiocb
->poll
;
1726 struct aio_poll_table apt
;
1729 /* reject any unknown events outside the normal event mask. */
1730 if ((u16
)iocb
->aio_buf
!= iocb
->aio_buf
)
1732 /* reject fields that are not defined for poll */
1733 if (iocb
->aio_offset
|| iocb
->aio_nbytes
|| iocb
->aio_rw_flags
)
1736 INIT_WORK(&req
->work
, aio_poll_complete_work
);
1737 req
->events
= demangle_poll(iocb
->aio_buf
) | EPOLLERR
| EPOLLHUP
;
1741 req
->cancelled
= false;
1743 apt
.pt
._qproc
= aio_poll_queue_proc
;
1744 apt
.pt
._key
= req
->events
;
1746 apt
.error
= -EINVAL
; /* same as no support for IOCB_CMD_POLL */
1748 /* initialized the list so that we can do list_empty checks */
1749 INIT_LIST_HEAD(&req
->wait
.entry
);
1750 init_waitqueue_func_entry(&req
->wait
, aio_poll_wake
);
1752 /* one for removal from waitqueue, one for this function */
1753 refcount_set(&aiocb
->ki_refcnt
, 2);
1755 mask
= vfs_poll(req
->file
, &apt
.pt
) & req
->events
;
1756 if (unlikely(!req
->head
)) {
1757 /* we did not manage to set up a waitqueue, done */
1761 spin_lock_irq(&ctx
->ctx_lock
);
1762 spin_lock(&req
->head
->lock
);
1764 /* wake_up context handles the rest */
1767 } else if (mask
|| apt
.error
) {
1768 /* if we get an error or a mask we are done */
1769 WARN_ON_ONCE(list_empty(&req
->wait
.entry
));
1770 list_del_init(&req
->wait
.entry
);
1772 /* actually waiting for an event */
1773 list_add_tail(&aiocb
->ki_list
, &ctx
->active_reqs
);
1774 aiocb
->ki_cancel
= aio_poll_cancel
;
1776 spin_unlock(&req
->head
->lock
);
1777 spin_unlock_irq(&ctx
->ctx_lock
);
1780 if (unlikely(apt
.error
))
1784 aio_poll_complete(aiocb
, mask
);
1789 static int __io_submit_one(struct kioctx
*ctx
, const struct iocb
*iocb
,
1790 struct iocb __user
*user_iocb
, bool compat
)
1792 struct aio_kiocb
*req
;
1795 /* enforce forwards compatibility on users */
1796 if (unlikely(iocb
->aio_reserved2
)) {
1797 pr_debug("EINVAL: reserve field set\n");
1801 /* prevent overflows */
1803 (iocb
->aio_buf
!= (unsigned long)iocb
->aio_buf
) ||
1804 (iocb
->aio_nbytes
!= (size_t)iocb
->aio_nbytes
) ||
1805 ((ssize_t
)iocb
->aio_nbytes
< 0)
1807 pr_debug("EINVAL: overflow check\n");
1811 if (!get_reqs_available(ctx
))
1815 req
= aio_get_req(ctx
);
1817 goto out_put_reqs_available
;
1819 req
->ki_filp
= fget(iocb
->aio_fildes
);
1821 if (unlikely(!req
->ki_filp
))
1824 if (iocb
->aio_flags
& IOCB_FLAG_RESFD
) {
1826 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1827 * instance of the file* now. The file descriptor must be
1828 * an eventfd() fd, and will be signaled for each completed
1829 * event using the eventfd_signal() function.
1831 req
->ki_eventfd
= eventfd_ctx_fdget((int) iocb
->aio_resfd
);
1832 if (IS_ERR(req
->ki_eventfd
)) {
1833 ret
= PTR_ERR(req
->ki_eventfd
);
1834 req
->ki_eventfd
= NULL
;
1839 ret
= put_user(KIOCB_KEY
, &user_iocb
->aio_key
);
1840 if (unlikely(ret
)) {
1841 pr_debug("EFAULT: aio_key\n");
1845 req
->ki_user_iocb
= user_iocb
;
1846 req
->ki_user_data
= iocb
->aio_data
;
1848 switch (iocb
->aio_lio_opcode
) {
1849 case IOCB_CMD_PREAD
:
1850 ret
= aio_read(&req
->rw
, iocb
, false, compat
);
1852 case IOCB_CMD_PWRITE
:
1853 ret
= aio_write(&req
->rw
, iocb
, false, compat
);
1855 case IOCB_CMD_PREADV
:
1856 ret
= aio_read(&req
->rw
, iocb
, true, compat
);
1858 case IOCB_CMD_PWRITEV
:
1859 ret
= aio_write(&req
->rw
, iocb
, true, compat
);
1861 case IOCB_CMD_FSYNC
:
1862 ret
= aio_fsync(&req
->fsync
, iocb
, false);
1864 case IOCB_CMD_FDSYNC
:
1865 ret
= aio_fsync(&req
->fsync
, iocb
, true);
1868 ret
= aio_poll(req
, iocb
);
1871 pr_debug("invalid aio operation %d\n", iocb
->aio_lio_opcode
);
1877 * If ret is 0, we'd either done aio_complete() ourselves or have
1878 * arranged for that to be done asynchronously. Anything non-zero
1879 * means that we need to destroy req ourselves.
1885 if (req
->ki_eventfd
)
1886 eventfd_ctx_put(req
->ki_eventfd
);
1888 out_put_reqs_available
:
1889 put_reqs_available(ctx
, 1);
1893 static int io_submit_one(struct kioctx
*ctx
, struct iocb __user
*user_iocb
,
1898 if (unlikely(copy_from_user(&iocb
, user_iocb
, sizeof(iocb
))))
1901 return __io_submit_one(ctx
, &iocb
, user_iocb
, compat
);
1905 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
1906 * the number of iocbs queued. May return -EINVAL if the aio_context
1907 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
1908 * *iocbpp[0] is not properly initialized, if the operation specified
1909 * is invalid for the file descriptor in the iocb. May fail with
1910 * -EFAULT if any of the data structures point to invalid data. May
1911 * fail with -EBADF if the file descriptor specified in the first
1912 * iocb is invalid. May fail with -EAGAIN if insufficient resources
1913 * are available to queue any iocbs. Will return 0 if nr is 0. Will
1914 * fail with -ENOSYS if not implemented.
1916 SYSCALL_DEFINE3(io_submit
, aio_context_t
, ctx_id
, long, nr
,
1917 struct iocb __user
* __user
*, iocbpp
)
1922 struct blk_plug plug
;
1924 if (unlikely(nr
< 0))
1927 ctx
= lookup_ioctx(ctx_id
);
1928 if (unlikely(!ctx
)) {
1929 pr_debug("EINVAL: invalid context id\n");
1933 if (nr
> ctx
->nr_events
)
1934 nr
= ctx
->nr_events
;
1936 if (nr
> AIO_PLUG_THRESHOLD
)
1937 blk_start_plug(&plug
);
1938 for (i
= 0; i
< nr
; i
++) {
1939 struct iocb __user
*user_iocb
;
1941 if (unlikely(get_user(user_iocb
, iocbpp
+ i
))) {
1946 ret
= io_submit_one(ctx
, user_iocb
, false);
1950 if (nr
> AIO_PLUG_THRESHOLD
)
1951 blk_finish_plug(&plug
);
1953 percpu_ref_put(&ctx
->users
);
1957 #ifdef CONFIG_COMPAT
1958 COMPAT_SYSCALL_DEFINE3(io_submit
, compat_aio_context_t
, ctx_id
,
1959 int, nr
, compat_uptr_t __user
*, iocbpp
)
1964 struct blk_plug plug
;
1966 if (unlikely(nr
< 0))
1969 ctx
= lookup_ioctx(ctx_id
);
1970 if (unlikely(!ctx
)) {
1971 pr_debug("EINVAL: invalid context id\n");
1975 if (nr
> ctx
->nr_events
)
1976 nr
= ctx
->nr_events
;
1978 if (nr
> AIO_PLUG_THRESHOLD
)
1979 blk_start_plug(&plug
);
1980 for (i
= 0; i
< nr
; i
++) {
1981 compat_uptr_t user_iocb
;
1983 if (unlikely(get_user(user_iocb
, iocbpp
+ i
))) {
1988 ret
= io_submit_one(ctx
, compat_ptr(user_iocb
), true);
1992 if (nr
> AIO_PLUG_THRESHOLD
)
1993 blk_finish_plug(&plug
);
1995 percpu_ref_put(&ctx
->users
);
2001 * Finds a given iocb for cancellation.
2003 static struct aio_kiocb
*
2004 lookup_kiocb(struct kioctx
*ctx
, struct iocb __user
*iocb
)
2006 struct aio_kiocb
*kiocb
;
2008 assert_spin_locked(&ctx
->ctx_lock
);
2010 /* TODO: use a hash or array, this sucks. */
2011 list_for_each_entry(kiocb
, &ctx
->active_reqs
, ki_list
) {
2012 if (kiocb
->ki_user_iocb
== iocb
)
2019 * Attempts to cancel an iocb previously passed to io_submit. If
2020 * the operation is successfully cancelled, the resulting event is
2021 * copied into the memory pointed to by result without being placed
2022 * into the completion queue and 0 is returned. May fail with
2023 * -EFAULT if any of the data structures pointed to are invalid.
2024 * May fail with -EINVAL if aio_context specified by ctx_id is
2025 * invalid. May fail with -EAGAIN if the iocb specified was not
2026 * cancelled. Will fail with -ENOSYS if not implemented.
2028 SYSCALL_DEFINE3(io_cancel
, aio_context_t
, ctx_id
, struct iocb __user
*, iocb
,
2029 struct io_event __user
*, result
)
2032 struct aio_kiocb
*kiocb
;
2036 if (unlikely(get_user(key
, &iocb
->aio_key
)))
2038 if (unlikely(key
!= KIOCB_KEY
))
2041 ctx
= lookup_ioctx(ctx_id
);
2045 spin_lock_irq(&ctx
->ctx_lock
);
2046 kiocb
= lookup_kiocb(ctx
, iocb
);
2048 ret
= kiocb
->ki_cancel(&kiocb
->rw
);
2049 list_del_init(&kiocb
->ki_list
);
2051 spin_unlock_irq(&ctx
->ctx_lock
);
2055 * The result argument is no longer used - the io_event is
2056 * always delivered via the ring buffer. -EINPROGRESS indicates
2057 * cancellation is progress:
2062 percpu_ref_put(&ctx
->users
);
2067 static long do_io_getevents(aio_context_t ctx_id
,
2070 struct io_event __user
*events
,
2071 struct timespec64
*ts
)
2073 ktime_t until
= ts
? timespec64_to_ktime(*ts
) : KTIME_MAX
;
2074 struct kioctx
*ioctx
= lookup_ioctx(ctx_id
);
2077 if (likely(ioctx
)) {
2078 if (likely(min_nr
<= nr
&& min_nr
>= 0))
2079 ret
= read_events(ioctx
, min_nr
, nr
, events
, until
);
2080 percpu_ref_put(&ioctx
->users
);
2087 * Attempts to read at least min_nr events and up to nr events from
2088 * the completion queue for the aio_context specified by ctx_id. If
2089 * it succeeds, the number of read events is returned. May fail with
2090 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
2091 * out of range, if timeout is out of range. May fail with -EFAULT
2092 * if any of the memory specified is invalid. May return 0 or
2093 * < min_nr if the timeout specified by timeout has elapsed
2094 * before sufficient events are available, where timeout == NULL
2095 * specifies an infinite timeout. Note that the timeout pointed to by
2096 * timeout is relative. Will fail with -ENOSYS if not implemented.
2098 #if !defined(CONFIG_64BIT_TIME) || defined(CONFIG_64BIT)
2100 SYSCALL_DEFINE5(io_getevents
, aio_context_t
, ctx_id
,
2103 struct io_event __user
*, events
,
2104 struct __kernel_timespec __user
*, timeout
)
2106 struct timespec64 ts
;
2109 if (timeout
&& unlikely(get_timespec64(&ts
, timeout
)))
2112 ret
= do_io_getevents(ctx_id
, min_nr
, nr
, events
, timeout
? &ts
: NULL
);
2113 if (!ret
&& signal_pending(current
))
2120 struct __aio_sigset
{
2121 const sigset_t __user
*sigmask
;
2125 SYSCALL_DEFINE6(io_pgetevents
,
2126 aio_context_t
, ctx_id
,
2129 struct io_event __user
*, events
,
2130 struct __kernel_timespec __user
*, timeout
,
2131 const struct __aio_sigset __user
*, usig
)
2133 struct __aio_sigset ksig
= { NULL
, };
2134 sigset_t ksigmask
, sigsaved
;
2135 struct timespec64 ts
;
2138 if (timeout
&& unlikely(get_timespec64(&ts
, timeout
)))
2141 if (usig
&& copy_from_user(&ksig
, usig
, sizeof(ksig
)))
2144 ret
= set_user_sigmask(ksig
.sigmask
, &ksigmask
, &sigsaved
, ksig
.sigsetsize
);
2148 ret
= do_io_getevents(ctx_id
, min_nr
, nr
, events
, timeout
? &ts
: NULL
);
2149 restore_user_sigmask(ksig
.sigmask
, &sigsaved
);
2150 if (signal_pending(current
) && !ret
)
2151 ret
= -ERESTARTNOHAND
;
2156 #if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)
2158 SYSCALL_DEFINE6(io_pgetevents_time32
,
2159 aio_context_t
, ctx_id
,
2162 struct io_event __user
*, events
,
2163 struct old_timespec32 __user
*, timeout
,
2164 const struct __aio_sigset __user
*, usig
)
2166 struct __aio_sigset ksig
= { NULL
, };
2167 sigset_t ksigmask
, sigsaved
;
2168 struct timespec64 ts
;
2171 if (timeout
&& unlikely(get_old_timespec32(&ts
, timeout
)))
2174 if (usig
&& copy_from_user(&ksig
, usig
, sizeof(ksig
)))
2178 ret
= set_user_sigmask(ksig
.sigmask
, &ksigmask
, &sigsaved
, ksig
.sigsetsize
);
2182 ret
= do_io_getevents(ctx_id
, min_nr
, nr
, events
, timeout
? &ts
: NULL
);
2183 restore_user_sigmask(ksig
.sigmask
, &sigsaved
);
2184 if (signal_pending(current
) && !ret
)
2185 ret
= -ERESTARTNOHAND
;
2192 #if defined(CONFIG_COMPAT_32BIT_TIME)
2194 SYSCALL_DEFINE5(io_getevents_time32
, __u32
, ctx_id
,
2197 struct io_event __user
*, events
,
2198 struct old_timespec32 __user
*, timeout
)
2200 struct timespec64 t
;
2203 if (timeout
&& get_old_timespec32(&t
, timeout
))
2206 ret
= do_io_getevents(ctx_id
, min_nr
, nr
, events
, timeout
? &t
: NULL
);
2207 if (!ret
&& signal_pending(current
))
2214 #ifdef CONFIG_COMPAT
2216 struct __compat_aio_sigset
{
2217 compat_sigset_t __user
*sigmask
;
2218 compat_size_t sigsetsize
;
2221 #if defined(CONFIG_COMPAT_32BIT_TIME)
2223 COMPAT_SYSCALL_DEFINE6(io_pgetevents
,
2224 compat_aio_context_t
, ctx_id
,
2225 compat_long_t
, min_nr
,
2227 struct io_event __user
*, events
,
2228 struct old_timespec32 __user
*, timeout
,
2229 const struct __compat_aio_sigset __user
*, usig
)
2231 struct __compat_aio_sigset ksig
= { NULL
, };
2232 sigset_t ksigmask
, sigsaved
;
2233 struct timespec64 t
;
2236 if (timeout
&& get_old_timespec32(&t
, timeout
))
2239 if (usig
&& copy_from_user(&ksig
, usig
, sizeof(ksig
)))
2242 ret
= set_compat_user_sigmask(ksig
.sigmask
, &ksigmask
, &sigsaved
, ksig
.sigsetsize
);
2246 ret
= do_io_getevents(ctx_id
, min_nr
, nr
, events
, timeout
? &t
: NULL
);
2247 restore_user_sigmask(ksig
.sigmask
, &sigsaved
);
2248 if (signal_pending(current
) && !ret
)
2249 ret
= -ERESTARTNOHAND
;
2256 COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64
,
2257 compat_aio_context_t
, ctx_id
,
2258 compat_long_t
, min_nr
,
2260 struct io_event __user
*, events
,
2261 struct __kernel_timespec __user
*, timeout
,
2262 const struct __compat_aio_sigset __user
*, usig
)
2264 struct __compat_aio_sigset ksig
= { NULL
, };
2265 sigset_t ksigmask
, sigsaved
;
2266 struct timespec64 t
;
2269 if (timeout
&& get_timespec64(&t
, timeout
))
2272 if (usig
&& copy_from_user(&ksig
, usig
, sizeof(ksig
)))
2275 ret
= set_compat_user_sigmask(ksig
.sigmask
, &ksigmask
, &sigsaved
, ksig
.sigsetsize
);
2279 ret
= do_io_getevents(ctx_id
, min_nr
, nr
, events
, timeout
? &t
: NULL
);
2280 restore_user_sigmask(ksig
.sigmask
, &sigsaved
);
2281 if (signal_pending(current
) && !ret
)
2282 ret
= -ERESTARTNOHAND
;