kernel-ark/fs/aio.c
Zach Brown 4faa528528 [PATCH] aio: revert lock_kiocb()
lock_kiocb() was introduced to serialize retrying and cancellation.  In the
process of doing so it tried to sleep waiting for KIF_LOCKED while holding
the ctx_lock spinlock.  Recent fixes have ensured that multiple concurrent
retries won't be attempted for a given iocb.  Cancel has other problems and
has no significant in-tree users that have been complaining about it.  So
for the immediate future we'll revert sleeping with the lock held and will
address proper cancellation and retry serialization in the future.

Signed-off-by: Zach Brown <zach.brown@oracle.com>
Acked-by: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-17 17:03:57 -07:00

1709 lines
44 KiB
C

/*
* An async IO implementation for Linux
* Written by Benjamin LaHaise <bcrl@kvack.org>
*
* Implements an efficient asynchronous io interface.
*
* Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved.
*
* See ../COPYING for licensing terms.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/time.h>
#include <linux/aio_abi.h>
#include <linux/module.h>
#include <linux/syscalls.h>
#define DEBUG 0
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/slab.h>
#include <linux/timer.h>
#include <linux/aio.h>
#include <linux/highmem.h>
#include <linux/workqueue.h>
#include <linux/security.h>
#include <linux/rcuref.h>
#include <asm/kmap_types.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
#if DEBUG > 1
#define dprintk printk
#else
#define dprintk(x...) do { ; } while (0)
#endif
/*------ sysctl variables----*/
atomic_t aio_nr = ATOMIC_INIT(0); /* current system wide number of aio requests */
unsigned aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
/*----end sysctl variables---*/
static kmem_cache_t *kiocb_cachep;
static kmem_cache_t *kioctx_cachep;
static struct workqueue_struct *aio_wq;
/* Used for rare fput completion. */
static void aio_fput_routine(void *);
static DECLARE_WORK(fput_work, aio_fput_routine, NULL);
static DEFINE_SPINLOCK(fput_lock);
static LIST_HEAD(fput_head);
static void aio_kick_handler(void *);
static void aio_queue_work(struct kioctx *);
/* aio_setup
* Creates the slab caches used by the aio routines, panic on
* failure as this is done early during the boot sequence.
*/
static int __init aio_setup(void)
{
kiocb_cachep = kmem_cache_create("kiocb", sizeof(struct kiocb),
0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
kioctx_cachep = kmem_cache_create("kioctx", sizeof(struct kioctx),
0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
aio_wq = create_workqueue("aio");
pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page));
return 0;
}
static void aio_free_ring(struct kioctx *ctx)
{
struct aio_ring_info *info = &ctx->ring_info;
long i;
for (i=0; i<info->nr_pages; i++)
put_page(info->ring_pages[i]);
if (info->mmap_size) {
down_write(&ctx->mm->mmap_sem);
do_munmap(ctx->mm, info->mmap_base, info->mmap_size);
up_write(&ctx->mm->mmap_sem);
}
if (info->ring_pages && info->ring_pages != info->internal_pages)
kfree(info->ring_pages);
info->ring_pages = NULL;
info->nr = 0;
}
static int aio_setup_ring(struct kioctx *ctx)
{
struct aio_ring *ring;
struct aio_ring_info *info = &ctx->ring_info;
unsigned nr_events = ctx->max_reqs;
unsigned long size;
int nr_pages;
/* Compensate for the ring buffer's head/tail overlap entry */
nr_events += 2; /* 1 is required, 2 for good luck */
size = sizeof(struct aio_ring);
size += sizeof(struct io_event) * nr_events;
nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT;
if (nr_pages < 0)
return -EINVAL;
nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event);
info->nr = 0;
info->ring_pages = info->internal_pages;
if (nr_pages > AIO_RING_PAGES) {
info->ring_pages = kmalloc(sizeof(struct page *) * nr_pages, GFP_KERNEL);
if (!info->ring_pages)
return -ENOMEM;
memset(info->ring_pages, 0, sizeof(struct page *) * nr_pages);
}
info->mmap_size = nr_pages * PAGE_SIZE;
dprintk("attempting mmap of %lu bytes\n", info->mmap_size);
down_write(&ctx->mm->mmap_sem);
info->mmap_base = do_mmap(NULL, 0, info->mmap_size,
PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE,
0);
if (IS_ERR((void *)info->mmap_base)) {
up_write(&ctx->mm->mmap_sem);
printk("mmap err: %ld\n", -info->mmap_base);
info->mmap_size = 0;
aio_free_ring(ctx);
return -EAGAIN;
}
dprintk("mmap address: 0x%08lx\n", info->mmap_base);
info->nr_pages = get_user_pages(current, ctx->mm,
info->mmap_base, nr_pages,
1, 0, info->ring_pages, NULL);
up_write(&ctx->mm->mmap_sem);
if (unlikely(info->nr_pages != nr_pages)) {
aio_free_ring(ctx);
return -EAGAIN;
}
ctx->user_id = info->mmap_base;
info->nr = nr_events; /* trusted copy */
ring = kmap_atomic(info->ring_pages[0], KM_USER0);
ring->nr = nr_events; /* user copy */
ring->id = ctx->user_id;
ring->head = ring->tail = 0;
ring->magic = AIO_RING_MAGIC;
ring->compat_features = AIO_RING_COMPAT_FEATURES;
ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
ring->header_length = sizeof(struct aio_ring);
kunmap_atomic(ring, KM_USER0);
return 0;
}
/* aio_ring_event: returns a pointer to the event at the given index from
* kmap_atomic(, km). Release the pointer with put_aio_ring_event();
*/
#define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
#define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
#define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
#define aio_ring_event(info, nr, km) ({ \
unsigned pos = (nr) + AIO_EVENTS_OFFSET; \
struct io_event *__event; \
__event = kmap_atomic( \
(info)->ring_pages[pos / AIO_EVENTS_PER_PAGE], km); \
__event += pos % AIO_EVENTS_PER_PAGE; \
__event; \
})
#define put_aio_ring_event(event, km) do { \
struct io_event *__event = (event); \
(void)__event; \
kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK), km); \
} while(0)
/* ioctx_alloc
* Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
*/
static struct kioctx *ioctx_alloc(unsigned nr_events)
{
struct mm_struct *mm;
struct kioctx *ctx;
/* Prevent overflows */
if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
(nr_events > (0x10000000U / sizeof(struct kiocb)))) {
pr_debug("ENOMEM: nr_events too high\n");
return ERR_PTR(-EINVAL);
}
if (nr_events > aio_max_nr)
return ERR_PTR(-EAGAIN);
ctx = kmem_cache_alloc(kioctx_cachep, GFP_KERNEL);
if (!ctx)
return ERR_PTR(-ENOMEM);
memset(ctx, 0, sizeof(*ctx));
ctx->max_reqs = nr_events;
mm = ctx->mm = current->mm;
atomic_inc(&mm->mm_count);
atomic_set(&ctx->users, 1);
spin_lock_init(&ctx->ctx_lock);
spin_lock_init(&ctx->ring_info.ring_lock);
init_waitqueue_head(&ctx->wait);
INIT_LIST_HEAD(&ctx->active_reqs);
INIT_LIST_HEAD(&ctx->run_list);
INIT_WORK(&ctx->wq, aio_kick_handler, ctx);
if (aio_setup_ring(ctx) < 0)
goto out_freectx;
/* limit the number of system wide aios */
atomic_add(ctx->max_reqs, &aio_nr); /* undone by __put_ioctx */
if (unlikely(atomic_read(&aio_nr) > aio_max_nr))
goto out_cleanup;
/* now link into global list. kludge. FIXME */
write_lock(&mm->ioctx_list_lock);
ctx->next = mm->ioctx_list;
mm->ioctx_list = ctx;
write_unlock(&mm->ioctx_list_lock);
dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
ctx, ctx->user_id, current->mm, ctx->ring_info.nr);
return ctx;
out_cleanup:
atomic_sub(ctx->max_reqs, &aio_nr);
ctx->max_reqs = 0; /* prevent __put_ioctx from sub'ing aio_nr */
__put_ioctx(ctx);
return ERR_PTR(-EAGAIN);
out_freectx:
mmdrop(mm);
kmem_cache_free(kioctx_cachep, ctx);
ctx = ERR_PTR(-ENOMEM);
dprintk("aio: error allocating ioctx %p\n", ctx);
return ctx;
}
/* aio_cancel_all
* Cancels all outstanding aio requests on an aio context. Used
* when the processes owning a context have all exited to encourage
* the rapid destruction of the kioctx.
*/
static void aio_cancel_all(struct kioctx *ctx)
{
int (*cancel)(struct kiocb *, struct io_event *);
struct io_event res;
spin_lock_irq(&ctx->ctx_lock);
ctx->dead = 1;
while (!list_empty(&ctx->active_reqs)) {
struct list_head *pos = ctx->active_reqs.next;
struct kiocb *iocb = list_kiocb(pos);
list_del_init(&iocb->ki_list);
cancel = iocb->ki_cancel;
kiocbSetCancelled(iocb);
if (cancel) {
iocb->ki_users++;
spin_unlock_irq(&ctx->ctx_lock);
cancel(iocb, &res);
spin_lock_irq(&ctx->ctx_lock);
}
}
spin_unlock_irq(&ctx->ctx_lock);
}
static void wait_for_all_aios(struct kioctx *ctx)
{
struct task_struct *tsk = current;
DECLARE_WAITQUEUE(wait, tsk);
if (!ctx->reqs_active)
return;
add_wait_queue(&ctx->wait, &wait);
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
while (ctx->reqs_active) {
schedule();
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
}
__set_task_state(tsk, TASK_RUNNING);
remove_wait_queue(&ctx->wait, &wait);
}
/* wait_on_sync_kiocb:
* Waits on the given sync kiocb to complete.
*/
ssize_t fastcall wait_on_sync_kiocb(struct kiocb *iocb)
{
while (iocb->ki_users) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (!iocb->ki_users)
break;
schedule();
}
__set_current_state(TASK_RUNNING);
return iocb->ki_user_data;
}
/* exit_aio: called when the last user of mm goes away. At this point,
* there is no way for any new requests to be submited or any of the
* io_* syscalls to be called on the context. However, there may be
* outstanding requests which hold references to the context; as they
* go away, they will call put_ioctx and release any pinned memory
* associated with the request (held via struct page * references).
*/
void fastcall exit_aio(struct mm_struct *mm)
{
struct kioctx *ctx = mm->ioctx_list;
mm->ioctx_list = NULL;
while (ctx) {
struct kioctx *next = ctx->next;
ctx->next = NULL;
aio_cancel_all(ctx);
wait_for_all_aios(ctx);
/*
* this is an overkill, but ensures we don't leave
* the ctx on the aio_wq
*/
flush_workqueue(aio_wq);
if (1 != atomic_read(&ctx->users))
printk(KERN_DEBUG
"exit_aio:ioctx still alive: %d %d %d\n",
atomic_read(&ctx->users), ctx->dead,
ctx->reqs_active);
put_ioctx(ctx);
ctx = next;
}
}
/* __put_ioctx
* Called when the last user of an aio context has gone away,
* and the struct needs to be freed.
*/
void fastcall __put_ioctx(struct kioctx *ctx)
{
unsigned nr_events = ctx->max_reqs;
if (unlikely(ctx->reqs_active))
BUG();
cancel_delayed_work(&ctx->wq);
flush_workqueue(aio_wq);
aio_free_ring(ctx);
mmdrop(ctx->mm);
ctx->mm = NULL;
pr_debug("__put_ioctx: freeing %p\n", ctx);
kmem_cache_free(kioctx_cachep, ctx);
atomic_sub(nr_events, &aio_nr);
}
/* aio_get_req
* Allocate a slot for an aio request. Increments the users count
* of the kioctx so that the kioctx stays around until all requests are
* complete. Returns NULL if no requests are free.
*
* Returns with kiocb->users set to 2. The io submit code path holds
* an extra reference while submitting the i/o.
* This prevents races between the aio code path referencing the
* req (after submitting it) and aio_complete() freeing the req.
*/
static struct kiocb *FASTCALL(__aio_get_req(struct kioctx *ctx));
static struct kiocb fastcall *__aio_get_req(struct kioctx *ctx)
{
struct kiocb *req = NULL;
struct aio_ring *ring;
int okay = 0;
req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
if (unlikely(!req))
return NULL;
req->ki_flags = 0;
req->ki_users = 2;
req->ki_key = 0;
req->ki_ctx = ctx;
req->ki_cancel = NULL;
req->ki_retry = NULL;
req->ki_dtor = NULL;
req->private = NULL;
INIT_LIST_HEAD(&req->ki_run_list);
/* Check if the completion queue has enough free space to
* accept an event from this io.
*/
spin_lock_irq(&ctx->ctx_lock);
ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0);
if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) {
list_add(&req->ki_list, &ctx->active_reqs);
get_ioctx(ctx);
ctx->reqs_active++;
okay = 1;
}
kunmap_atomic(ring, KM_USER0);
spin_unlock_irq(&ctx->ctx_lock);
if (!okay) {
kmem_cache_free(kiocb_cachep, req);
req = NULL;
}
return req;
}
static inline struct kiocb *aio_get_req(struct kioctx *ctx)
{
struct kiocb *req;
/* Handle a potential starvation case -- should be exceedingly rare as
* requests will be stuck on fput_head only if the aio_fput_routine is
* delayed and the requests were the last user of the struct file.
*/
req = __aio_get_req(ctx);
if (unlikely(NULL == req)) {
aio_fput_routine(NULL);
req = __aio_get_req(ctx);
}
return req;
}
static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
{
if (req->ki_dtor)
req->ki_dtor(req);
kmem_cache_free(kiocb_cachep, req);
ctx->reqs_active--;
if (unlikely(!ctx->reqs_active && ctx->dead))
wake_up(&ctx->wait);
}
static void aio_fput_routine(void *data)
{
spin_lock_irq(&fput_lock);
while (likely(!list_empty(&fput_head))) {
struct kiocb *req = list_kiocb(fput_head.next);
struct kioctx *ctx = req->ki_ctx;
list_del(&req->ki_list);
spin_unlock_irq(&fput_lock);
/* Complete the fput */
__fput(req->ki_filp);
/* Link the iocb into the context's free list */
spin_lock_irq(&ctx->ctx_lock);
really_put_req(ctx, req);
spin_unlock_irq(&ctx->ctx_lock);
put_ioctx(ctx);
spin_lock_irq(&fput_lock);
}
spin_unlock_irq(&fput_lock);
}
/* __aio_put_req
* Returns true if this put was the last user of the request.
*/
static int __aio_put_req(struct kioctx *ctx, struct kiocb *req)
{
dprintk(KERN_DEBUG "aio_put(%p): f_count=%d\n",
req, atomic_read(&req->ki_filp->f_count));
req->ki_users --;
if (unlikely(req->ki_users < 0))
BUG();
if (likely(req->ki_users))
return 0;
list_del(&req->ki_list); /* remove from active_reqs */
req->ki_cancel = NULL;
req->ki_retry = NULL;
/* Must be done under the lock to serialise against cancellation.
* Call this aio_fput as it duplicates fput via the fput_work.
*/
if (unlikely(rcuref_dec_and_test(&req->ki_filp->f_count))) {
get_ioctx(ctx);
spin_lock(&fput_lock);
list_add(&req->ki_list, &fput_head);
spin_unlock(&fput_lock);
queue_work(aio_wq, &fput_work);
} else
really_put_req(ctx, req);
return 1;
}
/* aio_put_req
* Returns true if this put was the last user of the kiocb,
* false if the request is still in use.
*/
int fastcall aio_put_req(struct kiocb *req)
{
struct kioctx *ctx = req->ki_ctx;
int ret;
spin_lock_irq(&ctx->ctx_lock);
ret = __aio_put_req(ctx, req);
spin_unlock_irq(&ctx->ctx_lock);
if (ret)
put_ioctx(ctx);
return ret;
}
/* Lookup an ioctx id. ioctx_list is lockless for reads.
* FIXME: this is O(n) and is only suitable for development.
*/
struct kioctx *lookup_ioctx(unsigned long ctx_id)
{
struct kioctx *ioctx;
struct mm_struct *mm;
mm = current->mm;
read_lock(&mm->ioctx_list_lock);
for (ioctx = mm->ioctx_list; ioctx; ioctx = ioctx->next)
if (likely(ioctx->user_id == ctx_id && !ioctx->dead)) {
get_ioctx(ioctx);
break;
}
read_unlock(&mm->ioctx_list_lock);
return ioctx;
}
/*
* use_mm
* Makes the calling kernel thread take on the specified
* mm context.
* Called by the retry thread execute retries within the
* iocb issuer's mm context, so that copy_from/to_user
* operations work seamlessly for aio.
* (Note: this routine is intended to be called only
* from a kernel thread context)
*/
static void use_mm(struct mm_struct *mm)
{
struct mm_struct *active_mm;
struct task_struct *tsk = current;
task_lock(tsk);
tsk->flags |= PF_BORROWED_MM;
active_mm = tsk->active_mm;
atomic_inc(&mm->mm_count);
tsk->mm = mm;
tsk->active_mm = mm;
/*
* Note that on UML this *requires* PF_BORROWED_MM to be set, otherwise
* it won't work. Update it accordingly if you change it here
*/
activate_mm(active_mm, mm);
task_unlock(tsk);
mmdrop(active_mm);
}
/*
* unuse_mm
* Reverses the effect of use_mm, i.e. releases the
* specified mm context which was earlier taken on
* by the calling kernel thread
* (Note: this routine is intended to be called only
* from a kernel thread context)
*
* Comments: Called with ctx->ctx_lock held. This nests
* task_lock instead ctx_lock.
*/
static void unuse_mm(struct mm_struct *mm)
{
struct task_struct *tsk = current;
task_lock(tsk);
tsk->flags &= ~PF_BORROWED_MM;
tsk->mm = NULL;
/* active_mm is still 'mm' */
enter_lazy_tlb(mm, tsk);
task_unlock(tsk);
}
/*
* Queue up a kiocb to be retried. Assumes that the kiocb
* has already been marked as kicked, and places it on
* the retry run list for the corresponding ioctx, if it
* isn't already queued. Returns 1 if it actually queued
* the kiocb (to tell the caller to activate the work
* queue to process it), or 0, if it found that it was
* already queued.
*
* Should be called with the spin lock iocb->ki_ctx->ctx_lock
* held
*/
static inline int __queue_kicked_iocb(struct kiocb *iocb)
{
struct kioctx *ctx = iocb->ki_ctx;
if (list_empty(&iocb->ki_run_list)) {
list_add_tail(&iocb->ki_run_list,
&ctx->run_list);
return 1;
}
return 0;
}
/* aio_run_iocb
* This is the core aio execution routine. It is
* invoked both for initial i/o submission and
* subsequent retries via the aio_kick_handler.
* Expects to be invoked with iocb->ki_ctx->lock
* already held. The lock is released and reaquired
* as needed during processing.
*
* Calls the iocb retry method (already setup for the
* iocb on initial submission) for operation specific
* handling, but takes care of most of common retry
* execution details for a given iocb. The retry method
* needs to be non-blocking as far as possible, to avoid
* holding up other iocbs waiting to be serviced by the
* retry kernel thread.
*
* The trickier parts in this code have to do with
* ensuring that only one retry instance is in progress
* for a given iocb at any time. Providing that guarantee
* simplifies the coding of individual aio operations as
* it avoids various potential races.
*/
static ssize_t aio_run_iocb(struct kiocb *iocb)
{
struct kioctx *ctx = iocb->ki_ctx;
ssize_t (*retry)(struct kiocb *);
ssize_t ret;
if (iocb->ki_retried++ > 1024*1024) {
printk("Maximal retry count. Bytes done %Zd\n",
iocb->ki_nbytes - iocb->ki_left);
return -EAGAIN;
}
if (!(iocb->ki_retried & 0xff)) {
pr_debug("%ld retry: %d of %d\n", iocb->ki_retried,
iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes);
}
if (!(retry = iocb->ki_retry)) {
printk("aio_run_iocb: iocb->ki_retry = NULL\n");
return 0;
}
/*
* We don't want the next retry iteration for this
* operation to start until this one has returned and
* updated the iocb state. However, wait_queue functions
* can trigger a kick_iocb from interrupt context in the
* meantime, indicating that data is available for the next
* iteration. We want to remember that and enable the
* next retry iteration _after_ we are through with
* this one.
*
* So, in order to be able to register a "kick", but
* prevent it from being queued now, we clear the kick
* flag, but make the kick code *think* that the iocb is
* still on the run list until we are actually done.
* When we are done with this iteration, we check if
* the iocb was kicked in the meantime and if so, queue
* it up afresh.
*/
kiocbClearKicked(iocb);
/*
* This is so that aio_complete knows it doesn't need to
* pull the iocb off the run list (We can't just call
* INIT_LIST_HEAD because we don't want a kick_iocb to
* queue this on the run list yet)
*/
iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL;
spin_unlock_irq(&ctx->ctx_lock);
/* Quit retrying if the i/o has been cancelled */
if (kiocbIsCancelled(iocb)) {
ret = -EINTR;
aio_complete(iocb, ret, 0);
/* must not access the iocb after this */
goto out;
}
/*
* Now we are all set to call the retry method in async
* context. By setting this thread's io_wait context
* to point to the wait queue entry inside the currently
* running iocb for the duration of the retry, we ensure
* that async notification wakeups are queued by the
* operation instead of blocking waits, and when notified,
* cause the iocb to be kicked for continuation (through
* the aio_wake_function callback).
*/
BUG_ON(current->io_wait != NULL);
current->io_wait = &iocb->ki_wait;
ret = retry(iocb);
current->io_wait = NULL;
if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) {
BUG_ON(!list_empty(&iocb->ki_wait.task_list));
aio_complete(iocb, ret, 0);
}
out:
spin_lock_irq(&ctx->ctx_lock);
if (-EIOCBRETRY == ret) {
/*
* OK, now that we are done with this iteration
* and know that there is more left to go,
* this is where we let go so that a subsequent
* "kick" can start the next iteration
*/
/* will make __queue_kicked_iocb succeed from here on */
INIT_LIST_HEAD(&iocb->ki_run_list);
/* we must queue the next iteration ourselves, if it
* has already been kicked */
if (kiocbIsKicked(iocb)) {
__queue_kicked_iocb(iocb);
/*
* __queue_kicked_iocb will always return 1 here, because
* iocb->ki_run_list is empty at this point so it should
* be safe to unconditionally queue the context into the
* work queue.
*/
aio_queue_work(ctx);
}
}
return ret;
}
/*
* __aio_run_iocbs:
* Process all pending retries queued on the ioctx
* run list.
* Assumes it is operating within the aio issuer's mm
* context. Expects to be called with ctx->ctx_lock held
*/
static int __aio_run_iocbs(struct kioctx *ctx)
{
struct kiocb *iocb;
LIST_HEAD(run_list);
list_splice_init(&ctx->run_list, &run_list);
while (!list_empty(&run_list)) {
iocb = list_entry(run_list.next, struct kiocb,
ki_run_list);
list_del(&iocb->ki_run_list);
/*
* Hold an extra reference while retrying i/o.
*/
iocb->ki_users++; /* grab extra reference */
aio_run_iocb(iocb);
if (__aio_put_req(ctx, iocb)) /* drop extra ref */
put_ioctx(ctx);
}
if (!list_empty(&ctx->run_list))
return 1;
return 0;
}
static void aio_queue_work(struct kioctx * ctx)
{
unsigned long timeout;
/*
* if someone is waiting, get the work started right
* away, otherwise, use a longer delay
*/
smp_mb();
if (waitqueue_active(&ctx->wait))
timeout = 1;
else
timeout = HZ/10;
queue_delayed_work(aio_wq, &ctx->wq, timeout);
}
/*
* aio_run_iocbs:
* Process all pending retries queued on the ioctx
* run list.
* Assumes it is operating within the aio issuer's mm
* context.
*/
static inline void aio_run_iocbs(struct kioctx *ctx)
{
int requeue;
spin_lock_irq(&ctx->ctx_lock);
requeue = __aio_run_iocbs(ctx);
spin_unlock_irq(&ctx->ctx_lock);
if (requeue)
aio_queue_work(ctx);
}
/*
* just like aio_run_iocbs, but keeps running them until
* the list stays empty
*/
static inline void aio_run_all_iocbs(struct kioctx *ctx)
{
spin_lock_irq(&ctx->ctx_lock);
while (__aio_run_iocbs(ctx))
;
spin_unlock_irq(&ctx->ctx_lock);
}
/*
* aio_kick_handler:
* Work queue handler triggered to process pending
* retries on an ioctx. Takes on the aio issuer's
* mm context before running the iocbs, so that
* copy_xxx_user operates on the issuer's address
* space.
* Run on aiod's context.
*/
static void aio_kick_handler(void *data)
{
struct kioctx *ctx = data;
mm_segment_t oldfs = get_fs();
int requeue;
set_fs(USER_DS);
use_mm(ctx->mm);
spin_lock_irq(&ctx->ctx_lock);
requeue =__aio_run_iocbs(ctx);
unuse_mm(ctx->mm);
spin_unlock_irq(&ctx->ctx_lock);
set_fs(oldfs);
/*
* we're in a worker thread already, don't use queue_delayed_work,
*/
if (requeue)
queue_work(aio_wq, &ctx->wq);
}
/*
* Called by kick_iocb to queue the kiocb for retry
* and if required activate the aio work queue to process
* it
*/
static void try_queue_kicked_iocb(struct kiocb *iocb)
{
struct kioctx *ctx = iocb->ki_ctx;
unsigned long flags;
int run = 0;
/* We're supposed to be the only path putting the iocb back on the run
* list. If we find that the iocb is *back* on a wait queue already
* than retry has happened before we could queue the iocb. This also
* means that the retry could have completed and freed our iocb, no
* good. */
BUG_ON((!list_empty(&iocb->ki_wait.task_list)));
spin_lock_irqsave(&ctx->ctx_lock, flags);
/* set this inside the lock so that we can't race with aio_run_iocb()
* testing it and putting the iocb on the run list under the lock */
if (!kiocbTryKick(iocb))
run = __queue_kicked_iocb(iocb);
spin_unlock_irqrestore(&ctx->ctx_lock, flags);
if (run)
aio_queue_work(ctx);
}
/*
* kick_iocb:
* Called typically from a wait queue callback context
* (aio_wake_function) to trigger a retry of the iocb.
* The retry is usually executed by aio workqueue
* threads (See aio_kick_handler).
*/
void fastcall kick_iocb(struct kiocb *iocb)
{
/* sync iocbs are easy: they can only ever be executing from a
* single context. */
if (is_sync_kiocb(iocb)) {
kiocbSetKicked(iocb);
wake_up_process(iocb->ki_obj.tsk);
return;
}
try_queue_kicked_iocb(iocb);
}
EXPORT_SYMBOL(kick_iocb);
/* aio_complete
* Called when the io request on the given iocb is complete.
* Returns true if this is the last user of the request. The
* only other user of the request can be the cancellation code.
*/
int fastcall aio_complete(struct kiocb *iocb, long res, long res2)
{
struct kioctx *ctx = iocb->ki_ctx;
struct aio_ring_info *info;
struct aio_ring *ring;
struct io_event *event;
unsigned long flags;
unsigned long tail;
int ret;
/* Special case handling for sync iocbs: events go directly
* into the iocb for fast handling. Note that this will not
* work if we allow sync kiocbs to be cancelled. in which
* case the usage count checks will have to move under ctx_lock
* for all cases.
*/
if (is_sync_kiocb(iocb)) {
int ret;
iocb->ki_user_data = res;
if (iocb->ki_users == 1) {
iocb->ki_users = 0;
ret = 1;
} else {
spin_lock_irq(&ctx->ctx_lock);
iocb->ki_users--;
ret = (0 == iocb->ki_users);
spin_unlock_irq(&ctx->ctx_lock);
}
/* sync iocbs put the task here for us */
wake_up_process(iocb->ki_obj.tsk);
return ret;
}
info = &ctx->ring_info;
/* add a completion event to the ring buffer.
* must be done holding ctx->ctx_lock to prevent
* other code from messing with the tail
* pointer since we might be called from irq
* context.
*/
spin_lock_irqsave(&ctx->ctx_lock, flags);
if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list))
list_del_init(&iocb->ki_run_list);
/*
* cancelled requests don't get events, userland was given one
* when the event got cancelled.
*/
if (kiocbIsCancelled(iocb))
goto put_rq;
ring = kmap_atomic(info->ring_pages[0], KM_IRQ1);
tail = info->tail;
event = aio_ring_event(info, tail, KM_IRQ0);
if (++tail >= info->nr)
tail = 0;
event->obj = (u64)(unsigned long)iocb->ki_obj.user;
event->data = iocb->ki_user_data;
event->res = res;
event->res2 = res2;
dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n",
ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
res, res2);
/* after flagging the request as done, we
* must never even look at it again
*/
smp_wmb(); /* make event visible before updating tail */
info->tail = tail;
ring->tail = tail;
put_aio_ring_event(event, KM_IRQ0);
kunmap_atomic(ring, KM_IRQ1);
pr_debug("added to ring %p at [%lu]\n", iocb, tail);
pr_debug("%ld retries: %d of %d\n", iocb->ki_retried,
iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes);
put_rq:
/* everything turned out well, dispose of the aiocb. */
ret = __aio_put_req(ctx, iocb);
spin_unlock_irqrestore(&ctx->ctx_lock, flags);
if (waitqueue_active(&ctx->wait))
wake_up(&ctx->wait);
if (ret)
put_ioctx(ctx);
return ret;
}
/* aio_read_evt
* Pull an event off of the ioctx's event ring. Returns the number of
* events fetched (0 or 1 ;-)
* FIXME: make this use cmpxchg.
* TODO: make the ringbuffer user mmap()able (requires FIXME).
*/
static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent)
{
struct aio_ring_info *info = &ioctx->ring_info;
struct aio_ring *ring;
unsigned long head;
int ret = 0;
ring = kmap_atomic(info->ring_pages[0], KM_USER0);
dprintk("in aio_read_evt h%lu t%lu m%lu\n",
(unsigned long)ring->head, (unsigned long)ring->tail,
(unsigned long)ring->nr);
if (ring->head == ring->tail)
goto out;
spin_lock(&info->ring_lock);
head = ring->head % info->nr;
if (head != ring->tail) {
struct io_event *evp = aio_ring_event(info, head, KM_USER1);
*ent = *evp;
head = (head + 1) % info->nr;
smp_mb(); /* finish reading the event before updatng the head */
ring->head = head;
ret = 1;
put_aio_ring_event(evp, KM_USER1);
}
spin_unlock(&info->ring_lock);
out:
kunmap_atomic(ring, KM_USER0);
dprintk("leaving aio_read_evt: %d h%lu t%lu\n", ret,
(unsigned long)ring->head, (unsigned long)ring->tail);
return ret;
}
struct aio_timeout {
struct timer_list timer;
int timed_out;
struct task_struct *p;
};
static void timeout_func(unsigned long data)
{
struct aio_timeout *to = (struct aio_timeout *)data;
to->timed_out = 1;
wake_up_process(to->p);
}
static inline void init_timeout(struct aio_timeout *to)
{
init_timer(&to->timer);
to->timer.data = (unsigned long)to;
to->timer.function = timeout_func;
to->timed_out = 0;
to->p = current;
}
static inline void set_timeout(long start_jiffies, struct aio_timeout *to,
const struct timespec *ts)
{
to->timer.expires = start_jiffies + timespec_to_jiffies(ts);
if (time_after(to->timer.expires, jiffies))
add_timer(&to->timer);
else
to->timed_out = 1;
}
static inline void clear_timeout(struct aio_timeout *to)
{
del_singleshot_timer_sync(&to->timer);
}
static int read_events(struct kioctx *ctx,
long min_nr, long nr,
struct io_event __user *event,
struct timespec __user *timeout)
{
long start_jiffies = jiffies;
struct task_struct *tsk = current;
DECLARE_WAITQUEUE(wait, tsk);
int ret;
int i = 0;
struct io_event ent;
struct aio_timeout to;
int retry = 0;
/* needed to zero any padding within an entry (there shouldn't be
* any, but C is fun!
*/
memset(&ent, 0, sizeof(ent));
retry:
ret = 0;
while (likely(i < nr)) {
ret = aio_read_evt(ctx, &ent);
if (unlikely(ret <= 0))
break;
dprintk("read event: %Lx %Lx %Lx %Lx\n",
ent.data, ent.obj, ent.res, ent.res2);
/* Could we split the check in two? */
ret = -EFAULT;
if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
dprintk("aio: lost an event due to EFAULT.\n");
break;
}
ret = 0;
/* Good, event copied to userland, update counts. */
event ++;
i ++;
}
if (min_nr <= i)
return i;
if (ret)
return ret;
/* End fast path */
/* racey check, but it gets redone */
if (!retry && unlikely(!list_empty(&ctx->run_list))) {
retry = 1;
aio_run_all_iocbs(ctx);
goto retry;
}
init_timeout(&to);
if (timeout) {
struct timespec ts;
ret = -EFAULT;
if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
goto out;
set_timeout(start_jiffies, &to, &ts);
}
while (likely(i < nr)) {
add_wait_queue_exclusive(&ctx->wait, &wait);
do {
set_task_state(tsk, TASK_INTERRUPTIBLE);
ret = aio_read_evt(ctx, &ent);
if (ret)
break;
if (min_nr <= i)
break;
ret = 0;
if (to.timed_out) /* Only check after read evt */
break;
schedule();
if (signal_pending(tsk)) {
ret = -EINTR;
break;
}
/*ret = aio_read_evt(ctx, &ent);*/
} while (1) ;
set_task_state(tsk, TASK_RUNNING);
remove_wait_queue(&ctx->wait, &wait);
if (unlikely(ret <= 0))
break;
ret = -EFAULT;
if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
dprintk("aio: lost an event due to EFAULT.\n");
break;
}
/* Good, event copied to userland, update counts. */
event ++;
i ++;
}
if (timeout)
clear_timeout(&to);
out:
return i ? i : ret;
}
/* Take an ioctx and remove it from the list of ioctx's. Protects
* against races with itself via ->dead.
*/
static void io_destroy(struct kioctx *ioctx)
{
struct mm_struct *mm = current->mm;
struct kioctx **tmp;
int was_dead;
/* delete the entry from the list is someone else hasn't already */
write_lock(&mm->ioctx_list_lock);
was_dead = ioctx->dead;
ioctx->dead = 1;
for (tmp = &mm->ioctx_list; *tmp && *tmp != ioctx;
tmp = &(*tmp)->next)
;
if (*tmp)
*tmp = ioctx->next;
write_unlock(&mm->ioctx_list_lock);
dprintk("aio_release(%p)\n", ioctx);
if (likely(!was_dead))
put_ioctx(ioctx); /* twice for the list */
aio_cancel_all(ioctx);
wait_for_all_aios(ioctx);
put_ioctx(ioctx); /* once for the lookup */
}
/* sys_io_setup:
* Create an aio_context capable of receiving at least nr_events.
* ctxp must not point to an aio_context that already exists, and
* must be initialized to 0 prior to the call. On successful
* creation of the aio_context, *ctxp is filled in with the resulting
* handle. May fail with -EINVAL if *ctxp is not initialized,
* if the specified nr_events exceeds internal limits. May fail
* with -EAGAIN if the specified nr_events exceeds the user's limit
* of available events. May fail with -ENOMEM if insufficient kernel
* resources are available. May fail with -EFAULT if an invalid
* pointer is passed for ctxp. Will fail with -ENOSYS if not
* implemented.
*/
asmlinkage long sys_io_setup(unsigned nr_events, aio_context_t __user *ctxp)
{
struct kioctx *ioctx = NULL;
unsigned long ctx;
long ret;
ret = get_user(ctx, ctxp);
if (unlikely(ret))
goto out;
ret = -EINVAL;
if (unlikely(ctx || (int)nr_events <= 0)) {
pr_debug("EINVAL: io_setup: ctx or nr_events > max\n");
goto out;
}
ioctx = ioctx_alloc(nr_events);
ret = PTR_ERR(ioctx);
if (!IS_ERR(ioctx)) {
ret = put_user(ioctx->user_id, ctxp);
if (!ret)
return 0;
get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */
io_destroy(ioctx);
}
out:
return ret;
}
/* sys_io_destroy:
* Destroy the aio_context specified. May cancel any outstanding
* AIOs and block on completion. Will fail with -ENOSYS if not
* implemented. May fail with -EFAULT if the context pointed to
* is invalid.
*/
asmlinkage long sys_io_destroy(aio_context_t ctx)
{
struct kioctx *ioctx = lookup_ioctx(ctx);
if (likely(NULL != ioctx)) {
io_destroy(ioctx);
return 0;
}
pr_debug("EINVAL: io_destroy: invalid context id\n");
return -EINVAL;
}
/*
* aio_p{read,write} are the default ki_retry methods for
* IO_CMD_P{READ,WRITE}. They maintains kiocb retry state around potentially
* multiple calls to f_op->aio_read(). They loop around partial progress
* instead of returning -EIOCBRETRY because they don't have the means to call
* kick_iocb().
*/
static ssize_t aio_pread(struct kiocb *iocb)
{
struct file *file = iocb->ki_filp;
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
ssize_t ret = 0;
do {
ret = file->f_op->aio_read(iocb, iocb->ki_buf,
iocb->ki_left, iocb->ki_pos);
/*
* Can't just depend on iocb->ki_left to determine
* whether we are done. This may have been a short read.
*/
if (ret > 0) {
iocb->ki_buf += ret;
iocb->ki_left -= ret;
}
/*
* For pipes and sockets we return once we have some data; for
* regular files we retry till we complete the entire read or
* find that we can't read any more data (e.g short reads).
*/
} while (ret > 0 && iocb->ki_left > 0 &&
!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode));
/* This means we must have transferred all that we could */
/* No need to retry anymore */
if ((ret == 0) || (iocb->ki_left == 0))
ret = iocb->ki_nbytes - iocb->ki_left;
return ret;
}
/* see aio_pread() */
static ssize_t aio_pwrite(struct kiocb *iocb)
{
struct file *file = iocb->ki_filp;
ssize_t ret = 0;
do {
ret = file->f_op->aio_write(iocb, iocb->ki_buf,
iocb->ki_left, iocb->ki_pos);
if (ret > 0) {
iocb->ki_buf += ret;
iocb->ki_left -= ret;
}
} while (ret > 0 && iocb->ki_left > 0);
if ((ret == 0) || (iocb->ki_left == 0))
ret = iocb->ki_nbytes - iocb->ki_left;
return ret;
}
static ssize_t aio_fdsync(struct kiocb *iocb)
{
struct file *file = iocb->ki_filp;
ssize_t ret = -EINVAL;
if (file->f_op->aio_fsync)
ret = file->f_op->aio_fsync(iocb, 1);
return ret;
}
static ssize_t aio_fsync(struct kiocb *iocb)
{
struct file *file = iocb->ki_filp;
ssize_t ret = -EINVAL;
if (file->f_op->aio_fsync)
ret = file->f_op->aio_fsync(iocb, 0);
return ret;
}
/*
* aio_setup_iocb:
* Performs the initial checks and aio retry method
* setup for the kiocb at the time of io submission.
*/
static ssize_t aio_setup_iocb(struct kiocb *kiocb)
{
struct file *file = kiocb->ki_filp;
ssize_t ret = 0;
switch (kiocb->ki_opcode) {
case IOCB_CMD_PREAD:
ret = -EBADF;
if (unlikely(!(file->f_mode & FMODE_READ)))
break;
ret = -EFAULT;
if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf,
kiocb->ki_left)))
break;
ret = -EINVAL;
if (file->f_op->aio_read)
kiocb->ki_retry = aio_pread;
break;
case IOCB_CMD_PWRITE:
ret = -EBADF;
if (unlikely(!(file->f_mode & FMODE_WRITE)))
break;
ret = -EFAULT;
if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf,
kiocb->ki_left)))
break;
ret = -EINVAL;
if (file->f_op->aio_write)
kiocb->ki_retry = aio_pwrite;
break;
case IOCB_CMD_FDSYNC:
ret = -EINVAL;
if (file->f_op->aio_fsync)
kiocb->ki_retry = aio_fdsync;
break;
case IOCB_CMD_FSYNC:
ret = -EINVAL;
if (file->f_op->aio_fsync)
kiocb->ki_retry = aio_fsync;
break;
default:
dprintk("EINVAL: io_submit: no operation provided\n");
ret = -EINVAL;
}
if (!kiocb->ki_retry)
return ret;
return 0;
}
/*
* aio_wake_function:
* wait queue callback function for aio notification,
* Simply triggers a retry of the operation via kick_iocb.
*
* This callback is specified in the wait queue entry in
* a kiocb (current->io_wait points to this wait queue
* entry when an aio operation executes; it is used
* instead of a synchronous wait when an i/o blocking
* condition is encountered during aio).
*
* Note:
* This routine is executed with the wait queue lock held.
* Since kick_iocb acquires iocb->ctx->ctx_lock, it nests
* the ioctx lock inside the wait queue lock. This is safe
* because this callback isn't used for wait queues which
* are nested inside ioctx lock (i.e. ctx->wait)
*/
static int aio_wake_function(wait_queue_t *wait, unsigned mode,
int sync, void *key)
{
struct kiocb *iocb = container_of(wait, struct kiocb, ki_wait);
list_del_init(&wait->task_list);
kick_iocb(iocb);
return 1;
}
int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
struct iocb *iocb)
{
struct kiocb *req;
struct file *file;
ssize_t ret;
/* enforce forwards compatibility on users */
if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2 ||
iocb->aio_reserved3)) {
pr_debug("EINVAL: io_submit: reserve field set\n");
return -EINVAL;
}
/* prevent overflows */
if (unlikely(
(iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
(iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
((ssize_t)iocb->aio_nbytes < 0)
)) {
pr_debug("EINVAL: io_submit: overflow check\n");
return -EINVAL;
}
file = fget(iocb->aio_fildes);
if (unlikely(!file))
return -EBADF;
req = aio_get_req(ctx); /* returns with 2 references to req */
if (unlikely(!req)) {
fput(file);
return -EAGAIN;
}
req->ki_filp = file;
ret = put_user(req->ki_key, &user_iocb->aio_key);
if (unlikely(ret)) {
dprintk("EFAULT: aio_key\n");
goto out_put_req;
}
req->ki_obj.user = user_iocb;
req->ki_user_data = iocb->aio_data;
req->ki_pos = iocb->aio_offset;
req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf;
req->ki_left = req->ki_nbytes = iocb->aio_nbytes;
req->ki_opcode = iocb->aio_lio_opcode;
init_waitqueue_func_entry(&req->ki_wait, aio_wake_function);
INIT_LIST_HEAD(&req->ki_wait.task_list);
req->ki_retried = 0;
ret = aio_setup_iocb(req);
if (ret)
goto out_put_req;
spin_lock_irq(&ctx->ctx_lock);
aio_run_iocb(req);
if (!list_empty(&ctx->run_list)) {
/* drain the run list */
while (__aio_run_iocbs(ctx))
;
}
spin_unlock_irq(&ctx->ctx_lock);
aio_put_req(req); /* drop extra ref to req */
return 0;
out_put_req:
aio_put_req(req); /* drop extra ref to req */
aio_put_req(req); /* drop i/o ref to req */
return ret;
}
/* sys_io_submit:
* Queue the nr iocbs pointed to by iocbpp for processing. Returns
* the number of iocbs queued. May return -EINVAL if the aio_context
* specified by ctx_id is invalid, if nr is < 0, if the iocb at
* *iocbpp[0] is not properly initialized, if the operation specified
* is invalid for the file descriptor in the iocb. May fail with
* -EFAULT if any of the data structures point to invalid data. May
* fail with -EBADF if the file descriptor specified in the first
* iocb is invalid. May fail with -EAGAIN if insufficient resources
* are available to queue any iocbs. Will return 0 if nr is 0. Will
* fail with -ENOSYS if not implemented.
*/
asmlinkage long sys_io_submit(aio_context_t ctx_id, long nr,
struct iocb __user * __user *iocbpp)
{
struct kioctx *ctx;
long ret = 0;
int i;
if (unlikely(nr < 0))
return -EINVAL;
if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
return -EFAULT;
ctx = lookup_ioctx(ctx_id);
if (unlikely(!ctx)) {
pr_debug("EINVAL: io_submit: invalid context id\n");
return -EINVAL;
}
/*
* AKPM: should this return a partial result if some of the IOs were
* successfully submitted?
*/
for (i=0; i<nr; i++) {
struct iocb __user *user_iocb;
struct iocb tmp;
if (unlikely(__get_user(user_iocb, iocbpp + i))) {
ret = -EFAULT;
break;
}
if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
ret = -EFAULT;
break;
}
ret = io_submit_one(ctx, user_iocb, &tmp);
if (ret)
break;
}
put_ioctx(ctx);
return i ? i : ret;
}
/* lookup_kiocb
* Finds a given iocb for cancellation.
* MUST be called with ctx->ctx_lock held.
*/
static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
u32 key)
{
struct list_head *pos;
/* TODO: use a hash or array, this sucks. */
list_for_each(pos, &ctx->active_reqs) {
struct kiocb *kiocb = list_kiocb(pos);
if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key)
return kiocb;
}
return NULL;
}
/* sys_io_cancel:
* Attempts to cancel an iocb previously passed to io_submit. If
* the operation is successfully cancelled, the resulting event is
* copied into the memory pointed to by result without being placed
* into the completion queue and 0 is returned. May fail with
* -EFAULT if any of the data structures pointed to are invalid.
* May fail with -EINVAL if aio_context specified by ctx_id is
* invalid. May fail with -EAGAIN if the iocb specified was not
* cancelled. Will fail with -ENOSYS if not implemented.
*/
asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb,
struct io_event __user *result)
{
int (*cancel)(struct kiocb *iocb, struct io_event *res);
struct kioctx *ctx;
struct kiocb *kiocb;
u32 key;
int ret;
ret = get_user(key, &iocb->aio_key);
if (unlikely(ret))
return -EFAULT;
ctx = lookup_ioctx(ctx_id);
if (unlikely(!ctx))
return -EINVAL;
spin_lock_irq(&ctx->ctx_lock);
ret = -EAGAIN;
kiocb = lookup_kiocb(ctx, iocb, key);
if (kiocb && kiocb->ki_cancel) {
cancel = kiocb->ki_cancel;
kiocb->ki_users ++;
kiocbSetCancelled(kiocb);
} else
cancel = NULL;
spin_unlock_irq(&ctx->ctx_lock);
if (NULL != cancel) {
struct io_event tmp;
pr_debug("calling cancel\n");
memset(&tmp, 0, sizeof(tmp));
tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user;
tmp.data = kiocb->ki_user_data;
ret = cancel(kiocb, &tmp);
if (!ret) {
/* Cancellation succeeded -- copy the result
* into the user's buffer.
*/
if (copy_to_user(result, &tmp, sizeof(tmp)))
ret = -EFAULT;
}
} else
ret = -EINVAL;
put_ioctx(ctx);
return ret;
}
/* io_getevents:
* Attempts to read at least min_nr events and up to nr events from
* the completion queue for the aio_context specified by ctx_id. May
* fail with -EINVAL if ctx_id is invalid, if min_nr is out of range,
* if nr is out of range, if when is out of range. May fail with
* -EFAULT if any of the memory specified to is invalid. May return
* 0 or < min_nr if no events are available and the timeout specified
* by when has elapsed, where when == NULL specifies an infinite
* timeout. Note that the timeout pointed to by when is relative and
* will be updated if not NULL and the operation blocks. Will fail
* with -ENOSYS if not implemented.
*/
asmlinkage long sys_io_getevents(aio_context_t ctx_id,
long min_nr,
long nr,
struct io_event __user *events,
struct timespec __user *timeout)
{
struct kioctx *ioctx = lookup_ioctx(ctx_id);
long ret = -EINVAL;
if (likely(ioctx)) {
if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0))
ret = read_events(ioctx, min_nr, nr, events, timeout);
put_ioctx(ioctx);
}
return ret;
}
__initcall(aio_setup);
EXPORT_SYMBOL(aio_complete);
EXPORT_SYMBOL(aio_put_req);
EXPORT_SYMBOL(wait_on_sync_kiocb);