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WSL2-Linux-Kernel
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WSL2-Linux-Kernel/fs/aio.c

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44 KiB
C
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/*
* 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 <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
long aio_run = 0; /* for testing only */
long aio_wakeups = 0; /* for testing only */
/*------ 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);
LIST_HEAD(fput_head);
static void aio_kick_handler(void *);
/* 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);
}
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 = 1 << KIF_LOCKED;
req->ki_users = 2;
req->ki_key = 0;
req->ki_ctx = ctx;
req->ki_cancel = NULL;
req->ki_retry = NULL;
req->ki_obj.user = 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);
req->ki_ctx = NULL;
req->ki_filp = NULL;
req->ki_obj.user = NULL;
req->ki_dtor = NULL;
req->private = NULL;
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(atomic_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;
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.
*/
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);
iocb->ki_queued++;
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 (kick %ld, Q %ld run %ld, wake %ld)\n",
iocb->ki_retried,
iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes,
iocb->ki_kicked, iocb->ki_queued, aio_run, aio_wakeups);
}
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 (-EIOCBRETRY != ret) {
if (-EIOCBQUEUED != ret) {
BUG_ON(!list_empty(&iocb->ki_wait.task_list));
aio_complete(iocb, ret, 0);
/* must not access the iocb after this */
}
} else {
/*
* Issue an additional retry to avoid waiting forever if
* no waits were queued (e.g. in case of a short read).
*/
if (list_empty(&iocb->ki_wait.task_list))
kiocbSetKicked(iocb);
}
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);
}
}
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;
int count = 0;
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);
count++;
}
aio_run++;
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
*/
void queue_kicked_iocb(struct kiocb *iocb)
{
struct kioctx *ctx = iocb->ki_ctx;
unsigned long flags;
int run = 0;
WARN_ON((!list_empty(&iocb->ki_wait.task_list)));
spin_lock_irqsave(&ctx->ctx_lock, flags);
run = __queue_kicked_iocb(iocb);
spin_unlock_irqrestore(&ctx->ctx_lock, flags);
if (run) {
aio_queue_work(ctx);
aio_wakeups++;
}
}
/*
* 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;
}
iocb->ki_kicked++;
/* If its already kicked we shouldn't queue it again */
if (!kiocbTryKick(iocb)) {
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);
tail = (tail + 1) % info->nr;
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 (kicked %ld, Q %ld run %ld wake %ld)\n",
iocb->ki_retried,
iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes,
iocb->ki_kicked, iocb->ki_queued, aio_run, aio_wakeups);
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 event_loop = 0; /* testing only */
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();
event_loop++;
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:
pr_debug("event loop executed %d times\n", event_loop);
pr_debug("aio_run %ld\n", aio_run);
pr_debug("aio_wakeups %ld\n", aio_wakeups);
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;
}
/*
* Default retry method for aio_read (also used for first time submit)
* Responsible for updating iocb state as retries progress
*/
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;
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).
*/
if (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))
ret = -EIOCBRETRY;
}
/* 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;
}
/*
* Default retry method for aio_write (also used for first time submit)
* Responsible for updating iocb state as retries progress
*/
static ssize_t aio_pwrite(struct kiocb *iocb)
{
struct file *file = iocb->ki_filp;
ssize_t ret = 0;
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;
ret = -EIOCBRETRY;
}
/* 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;
}
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.
*/
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)
*/
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;
iocb->aio_key = req->ki_key;
ret = put_user(iocb->aio_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_run_list.next = req->ki_run_list.prev = NULL;
req->ki_retry = NULL;
req->ki_retried = 0;
req->ki_kicked = 0;
req->ki_queued = 0;
aio_run = 0;
aio_wakeups = 0;
ret = aio_setup_iocb(req);
if (ret)
goto out_put_req;
spin_lock_irq(&ctx->ctx_lock);
list_add_tail(&req->ki_run_list, &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.
*/
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
printk(KERN_DEBUG "iocb has no cancel operation\n");
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);
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