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

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48 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>
#include <linux/backing-dev.h>
#include <linux/uio.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/mmu_context.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/eventfd.h>
#include <linux/blkdev.h>
#include <linux/mempool.h>
#include <linux/hash.h>
#include <linux/compat.h>
#include <asm/kmap_types.h>
#include <asm/uaccess.h>
#if DEBUG > 1
#define dprintk printk
#else
#define dprintk(x...) do { ; } while (0)
#endif
/*------ sysctl variables----*/
static DEFINE_SPINLOCK(aio_nr_lock);
unsigned long aio_nr; /* current system wide number of aio requests */
unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
/*----end sysctl variables---*/
static struct kmem_cache *kiocb_cachep;
static struct kmem_cache *kioctx_cachep;
static struct workqueue_struct *aio_wq;
/* Used for rare fput completion. */
static void aio_fput_routine(struct work_struct *);
static DECLARE_WORK(fput_work, aio_fput_routine);
static DEFINE_SPINLOCK(fput_lock);
static LIST_HEAD(fput_head);
#define AIO_BATCH_HASH_BITS 3 /* allocated on-stack, so don't go crazy */
#define AIO_BATCH_HASH_SIZE (1 << AIO_BATCH_HASH_BITS)
struct aio_batch_entry {
struct hlist_node list;
struct address_space *mapping;
};
mempool_t *abe_pool;
static void aio_kick_handler(struct work_struct *);
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(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
aio_wq = alloc_workqueue("aio", 0, 1); /* used to limit concurrency */
abe_pool = mempool_create_kmalloc_pool(1, sizeof(struct aio_batch_entry));
BUG_ON(!aio_wq || !abe_pool);
pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page));
return 0;
}
__initcall(aio_setup);
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 = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
if (!info->ring_pages)
return -ENOMEM;
}
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_ANONYMOUS|MAP_PRIVATE,
0);
if (IS_ERR((void *)info->mmap_base)) {
up_write(&ctx->mm->mmap_sem);
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)
static void ctx_rcu_free(struct rcu_head *head)
{
struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
unsigned nr_events = ctx->max_reqs;
kmem_cache_free(kioctx_cachep, ctx);
if (nr_events) {
spin_lock(&aio_nr_lock);
BUG_ON(aio_nr - nr_events > aio_nr);
aio_nr -= nr_events;
spin_unlock(&aio_nr_lock);
}
}
/* __put_ioctx
* Called when the last user of an aio context has gone away,
* and the struct needs to be freed.
*/
static void __put_ioctx(struct kioctx *ctx)
{
BUG_ON(ctx->reqs_active);
cancel_delayed_work(&ctx->wq);
cancel_work_sync(&ctx->wq.work);
aio_free_ring(ctx);
mmdrop(ctx->mm);
ctx->mm = NULL;
pr_debug("__put_ioctx: freeing %p\n", ctx);
call_rcu(&ctx->rcu_head, ctx_rcu_free);
}
static inline void get_ioctx(struct kioctx *kioctx)
{
BUG_ON(atomic_read(&kioctx->users) <= 0);
atomic_inc(&kioctx->users);
}
static inline int try_get_ioctx(struct kioctx *kioctx)
{
return atomic_inc_not_zero(&kioctx->users);
}
static inline void put_ioctx(struct kioctx *kioctx)
{
BUG_ON(atomic_read(&kioctx->users) <= 0);
if (unlikely(atomic_dec_and_test(&kioctx->users)))
__put_ioctx(kioctx);
}
/* 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;
int did_sync = 0;
/* 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 ((unsigned long)nr_events > aio_max_nr)
return ERR_PTR(-EAGAIN);
ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
if (!ctx)
return ERR_PTR(-ENOMEM);
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_DELAYED_WORK(&ctx->wq, aio_kick_handler);
if (aio_setup_ring(ctx) < 0)
goto out_freectx;
/* limit the number of system wide aios */
do {
spin_lock_bh(&aio_nr_lock);
if (aio_nr + nr_events > aio_max_nr ||
aio_nr + nr_events < aio_nr)
ctx->max_reqs = 0;
else
aio_nr += ctx->max_reqs;
spin_unlock_bh(&aio_nr_lock);
if (ctx->max_reqs || did_sync)
break;
/* wait for rcu callbacks to have completed before giving up */
synchronize_rcu();
did_sync = 1;
ctx->max_reqs = nr_events;
} while (1);
if (ctx->max_reqs == 0)
goto out_cleanup;
/* now link into global list. */
spin_lock(&mm->ioctx_lock);
hlist_add_head_rcu(&ctx->list, &mm->ioctx_list);
spin_unlock(&mm->ioctx_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:
__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);
spin_lock_irq(&ctx->ctx_lock);
if (!ctx->reqs_active)
goto out;
add_wait_queue(&ctx->wait, &wait);
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
while (ctx->reqs_active) {
spin_unlock_irq(&ctx->ctx_lock);
io_schedule();
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
spin_lock_irq(&ctx->ctx_lock);
}
__set_task_state(tsk, TASK_RUNNING);
remove_wait_queue(&ctx->wait, &wait);
out:
spin_unlock_irq(&ctx->ctx_lock);
}
/* wait_on_sync_kiocb:
* Waits on the given sync kiocb to complete.
*/
ssize_t wait_on_sync_kiocb(struct kiocb *iocb)
{
while (iocb->ki_users) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (!iocb->ki_users)
break;
io_schedule();
}
__set_current_state(TASK_RUNNING);
return iocb->ki_user_data;
}
EXPORT_SYMBOL(wait_on_sync_kiocb);
/* 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 exit_aio(struct mm_struct *mm)
{
struct kioctx *ctx;
while (!hlist_empty(&mm->ioctx_list)) {
ctx = hlist_entry(mm->ioctx_list.first, struct kioctx, list);
hlist_del_rcu(&ctx->list);
aio_cancel_all(ctx);
wait_for_all_aios(ctx);
/*
* Ensure we don't leave the ctx on the aio_wq
*/
cancel_work_sync(&ctx->wq.work);
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);
}
}
/* 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 *__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;
req->ki_iovec = NULL;
INIT_LIST_HEAD(&req->ki_run_list);
req->ki_eventfd = NULL;
/* 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);
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)
{
assert_spin_locked(&ctx->ctx_lock);
if (req->ki_eventfd != NULL)
eventfd_ctx_put(req->ki_eventfd);
if (req->ki_dtor)
req->ki_dtor(req);
if (req->ki_iovec != &req->ki_inline_vec)
kfree(req->ki_iovec);
kmem_cache_free(kiocb_cachep, req);
ctx->reqs_active--;
if (unlikely(!ctx->reqs_active && ctx->dead))
wake_up_all(&ctx->wait);
}
static void aio_fput_routine(struct work_struct *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(s) */
if (req->ki_filp != NULL)
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=%ld\n",
req, atomic_long_read(&req->ki_filp->f_count));
assert_spin_locked(&ctx->ctx_lock);
req->ki_users--;
BUG_ON(req->ki_users < 0);
if (likely(req->ki_users))
return 0;
list_del(&req->ki_list); /* remove from active_reqs */
req->ki_cancel = NULL;
req->ki_retry = NULL;
/*
* Try to optimize the aio and eventfd file* puts, by avoiding to
* schedule work in case it is not final fput() time. In normal cases,
* we would not be holding the last reference to the file*, so
* this function will be executed w/out any aio kthread wakeup.
*/
if (unlikely(!fput_atomic(req->ki_filp))) {
get_ioctx(ctx);
spin_lock(&fput_lock);
list_add(&req->ki_list, &fput_head);
spin_unlock(&fput_lock);
schedule_work(&fput_work);
} else {
req->ki_filp = NULL;
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 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);
return ret;
}
EXPORT_SYMBOL(aio_put_req);
static struct kioctx *lookup_ioctx(unsigned long ctx_id)
{
struct mm_struct *mm = current->mm;
struct kioctx *ctx, *ret = NULL;
struct hlist_node *n;
rcu_read_lock();
hlist_for_each_entry_rcu(ctx, n, &mm->ioctx_list, list) {
/*
* RCU protects us against accessing freed memory but
* we have to be careful not to get a reference when the
* reference count already dropped to 0 (ctx->dead test
* is unreliable because of races).
*/
if (ctx->user_id == ctx_id && !ctx->dead && try_get_ioctx(ctx)){
ret = ctx;
break;
}
}
rcu_read_unlock();
return ret;
}
/*
* 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.
*/
static inline int __queue_kicked_iocb(struct kiocb *iocb)
{
struct kioctx *ctx = iocb->ki_ctx;
assert_spin_locked(&ctx->ctx_lock);
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 reacquired
* 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 (!(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.
*/
ret = retry(iocb);
if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) {
/*
* There's no easy way to restart the syscall since other AIO's
* may be already running. Just fail this IO with EINTR.
*/
if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
ret == -ERESTARTNOHAND || ret == -ERESTART_RESTARTBLOCK))
ret = -EINTR;
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.
*/
static int __aio_run_iocbs(struct kioctx *ctx)
{
struct kiocb *iocb;
struct list_head run_list;
assert_spin_locked(&ctx->ctx_lock);
list_replace_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);
__aio_put_req(ctx, iocb);
}
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_all_iocbs:
* Process all pending retries queued on the ioctx
* run list, and keep running them until the list
* stays empty.
* Assumes it is operating within the aio issuer's mm context.
*/
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(struct work_struct *work)
{
struct kioctx *ctx = container_of(work, struct kioctx, wq.work);
mm_segment_t oldfs = get_fs();
struct mm_struct *mm;
int requeue;
set_fs(USER_DS);
use_mm(ctx->mm);
spin_lock_irq(&ctx->ctx_lock);
requeue =__aio_run_iocbs(ctx);
mm = ctx->mm;
spin_unlock_irq(&ctx->ctx_lock);
unuse_mm(mm);
set_fs(oldfs);
/*
* we're in a worker thread already, don't use queue_delayed_work,
*/
if (requeue)
queue_delayed_work(aio_wq, &ctx->wq, 0);
}
/*
* 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;
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
* to trigger a retry of the iocb.
* The retry is usually executed by aio workqueue
* threads (See aio_kick_handler).
*/
void 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 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
* - the sync task with the iocb in its stack holds the single iocb
* ref, no other paths have a way to get another ref
* - the sync task helpfully left a reference to itself in the iocb
*/
if (is_sync_kiocb(iocb)) {
BUG_ON(iocb->ki_users != 1);
iocb->ki_user_data = res;
iocb->ki_users = 0;
wake_up_process(iocb->ki_obj.tsk);
return 1;
}
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);
/*
* Check if the user asked us to deliver the result through an
* eventfd. The eventfd_signal() function is safe to be called
* from IRQ context.
*/
if (iocb->ki_eventfd != NULL)
eventfd_signal(iocb->ki_eventfd, 1);
put_rq:
/* everything turned out well, dispose of the aiocb. */
ret = __aio_put_req(ctx, iocb);
/*
* We have to order our ring_info tail store above and test
* of the wait list below outside the wait lock. This is
* like in wake_up_bit() where clearing a bit has to be
* ordered with the unlocked test.
*/
smp_mb();
if (waitqueue_active(&ctx->wait))
wake_up(&ctx->wait);
spin_unlock_irqrestore(&ctx->ctx_lock, flags);
return ret;
}
EXPORT_SYMBOL(aio_complete);
/* 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)
{
setup_timer_on_stack(&to->timer, timeout_func, (unsigned long) to);
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;
if (unlikely(ctx->dead)) {
ret = -EINVAL;
break;
}
if (to.timed_out) /* Only check after read evt */
break;
/* Try to only show up in io wait if there are ops
* in flight */
if (ctx->reqs_active)
io_schedule();
else
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:
destroy_timer_on_stack(&to.timer);
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;
int was_dead;
/* delete the entry from the list is someone else hasn't already */
spin_lock(&mm->ioctx_lock);
was_dead = ioctx->dead;
ioctx->dead = 1;
hlist_del_rcu(&ioctx->list);
spin_unlock(&mm->ioctx_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);
/*
* Wake up any waiters. The setting of ctx->dead must be seen
* by other CPUs at this point. Right now, we rely on the
* locking done by the above calls to ensure this consistency.
*/
wake_up_all(&ioctx->wait);
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.
*/
SYSCALL_DEFINE2(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 || nr_events == 0)) {
pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
ctx, nr_events);
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 -EINVAL if the context pointed to
* is invalid.
*/
SYSCALL_DEFINE1(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;
}
static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret)
{
struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg];
BUG_ON(ret <= 0);
while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) {
ssize_t this = min((ssize_t)iov->iov_len, ret);
iov->iov_base += this;
iov->iov_len -= this;
iocb->ki_left -= this;
ret -= this;
if (iov->iov_len == 0) {
iocb->ki_cur_seg++;
iov++;
}
}
/* the caller should not have done more io than what fit in
* the remaining iovecs */
BUG_ON(ret > 0 && iocb->ki_left == 0);
}
static ssize_t aio_rw_vect_retry(struct kiocb *iocb)
{
struct file *file = iocb->ki_filp;
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
ssize_t (*rw_op)(struct kiocb *, const struct iovec *,
unsigned long, loff_t);
ssize_t ret = 0;
unsigned short opcode;
if ((iocb->ki_opcode == IOCB_CMD_PREADV) ||
(iocb->ki_opcode == IOCB_CMD_PREAD)) {
rw_op = file->f_op->aio_read;
opcode = IOCB_CMD_PREADV;
} else {
rw_op = file->f_op->aio_write;
opcode = IOCB_CMD_PWRITEV;
}
/* This matches the pread()/pwrite() logic */
if (iocb->ki_pos < 0)
return -EINVAL;
do {
ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg],
iocb->ki_nr_segs - iocb->ki_cur_seg,
iocb->ki_pos);
if (ret > 0)
aio_advance_iovec(iocb, ret);
/* retry all partial writes. retry partial reads as long as its a
* regular file. */
} while (ret > 0 && iocb->ki_left > 0 &&
(opcode == IOCB_CMD_PWRITEV ||
(!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;
/* If we managed to write some out we return that, rather than
* the eventual error. */
if (opcode == IOCB_CMD_PWRITEV
&& ret < 0 && ret != -EIOCBQUEUED && ret != -EIOCBRETRY
&& iocb->ki_nbytes - iocb->ki_left)
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;
}
static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb, bool compat)
{
ssize_t ret;
#ifdef CONFIG_COMPAT
if (compat)
ret = compat_rw_copy_check_uvector(type,
(struct compat_iovec __user *)kiocb->ki_buf,
kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
&kiocb->ki_iovec);
else
#endif
ret = rw_copy_check_uvector(type,
(struct iovec __user *)kiocb->ki_buf,
kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
&kiocb->ki_iovec);
if (ret < 0)
goto out;
kiocb->ki_nr_segs = kiocb->ki_nbytes;
kiocb->ki_cur_seg = 0;
/* ki_nbytes/left now reflect bytes instead of segs */
kiocb->ki_nbytes = ret;
kiocb->ki_left = ret;
ret = 0;
out:
return ret;
}
static ssize_t aio_setup_single_vector(struct kiocb *kiocb)
{
kiocb->ki_iovec = &kiocb->ki_inline_vec;
kiocb->ki_iovec->iov_base = kiocb->ki_buf;
kiocb->ki_iovec->iov_len = kiocb->ki_left;
kiocb->ki_nr_segs = 1;
kiocb->ki_cur_seg = 0;
return 0;
}
/*
* 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, bool compat)
{
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 = security_file_permission(file, MAY_READ);
if (unlikely(ret))
break;
ret = aio_setup_single_vector(kiocb);
if (ret)
break;
ret = -EINVAL;
if (file->f_op->aio_read)
kiocb->ki_retry = aio_rw_vect_retry;
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 = security_file_permission(file, MAY_WRITE);
if (unlikely(ret))
break;
ret = aio_setup_single_vector(kiocb);
if (ret)
break;
ret = -EINVAL;
if (file->f_op->aio_write)
kiocb->ki_retry = aio_rw_vect_retry;
break;
case IOCB_CMD_PREADV:
ret = -EBADF;
if (unlikely(!(file->f_mode & FMODE_READ)))
break;
ret = security_file_permission(file, MAY_READ);
if (unlikely(ret))
break;
ret = aio_setup_vectored_rw(READ, kiocb, compat);
if (ret)
break;
ret = -EINVAL;
if (file->f_op->aio_read)
kiocb->ki_retry = aio_rw_vect_retry;
break;
case IOCB_CMD_PWRITEV:
ret = -EBADF;
if (unlikely(!(file->f_mode & FMODE_WRITE)))
break;
ret = security_file_permission(file, MAY_WRITE);
if (unlikely(ret))
break;
ret = aio_setup_vectored_rw(WRITE, kiocb, compat);
if (ret)
break;
ret = -EINVAL;
if (file->f_op->aio_write)
kiocb->ki_retry = aio_rw_vect_retry;
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;
}
static void aio_batch_add(struct address_space *mapping,
struct hlist_head *batch_hash)
{
struct aio_batch_entry *abe;
struct hlist_node *pos;
unsigned bucket;
bucket = hash_ptr(mapping, AIO_BATCH_HASH_BITS);
hlist_for_each_entry(abe, pos, &batch_hash[bucket], list) {
if (abe->mapping == mapping)
return;
}
abe = mempool_alloc(abe_pool, GFP_KERNEL);
/*
* we should be using igrab here, but
* we don't want to hammer on the global
* inode spinlock just to take an extra
* reference on a file that we must already
* have a reference to.
*
* When we're called, we always have a reference
* on the file, so we must always have a reference
* on the inode, so ihold() is safe here.
*/
ihold(mapping->host);
abe->mapping = mapping;
hlist_add_head(&abe->list, &batch_hash[bucket]);
return;
}
static void aio_batch_free(struct hlist_head *batch_hash)
{
struct aio_batch_entry *abe;
struct hlist_node *pos, *n;
int i;
for (i = 0; i < AIO_BATCH_HASH_SIZE; i++) {
hlist_for_each_entry_safe(abe, pos, n, &batch_hash[i], list) {
blk_run_address_space(abe->mapping);
iput(abe->mapping->host);
hlist_del(&abe->list);
mempool_free(abe, abe_pool);
}
}
}
static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
struct iocb *iocb, struct hlist_head *batch_hash,
bool compat)
{
struct kiocb *req;
struct file *file;
ssize_t ret;
/* enforce forwards compatibility on users */
if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
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;
if (iocb->aio_flags & IOCB_FLAG_RESFD) {
/*
* If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
* instance of the file* now. The file descriptor must be
* an eventfd() fd, and will be signaled for each completed
* event using the eventfd_signal() function.
*/
req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
if (IS_ERR(req->ki_eventfd)) {
ret = PTR_ERR(req->ki_eventfd);
req->ki_eventfd = NULL;
goto out_put_req;
}
}
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;
ret = aio_setup_iocb(req, compat);
if (ret)
goto out_put_req;
spin_lock_irq(&ctx->ctx_lock);
/*
* We could have raced with io_destroy() and are currently holding a
* reference to ctx which should be destroyed. We cannot submit IO
* since ctx gets freed as soon as io_submit() puts its reference. The
* check here is reliable: io_destroy() sets ctx->dead before waiting
* for outstanding IO and the barrier between these two is realized by
* unlock of mm->ioctx_lock and lock of ctx->ctx_lock. Analogously we
* increment ctx->reqs_active before checking for ctx->dead and the
* barrier is realized by unlock and lock of ctx->ctx_lock. Thus if we
* don't see ctx->dead set here, io_destroy() waits for our IO to
* finish.
*/
if (ctx->dead) {
spin_unlock_irq(&ctx->ctx_lock);
ret = -EINVAL;
goto out_put_req;
}
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);
if (req->ki_opcode == IOCB_CMD_PREAD ||
req->ki_opcode == IOCB_CMD_PREADV ||
req->ki_opcode == IOCB_CMD_PWRITE ||
req->ki_opcode == IOCB_CMD_PWRITEV)
aio_batch_add(file->f_mapping, batch_hash);
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;
}
long do_io_submit(aio_context_t ctx_id, long nr,
struct iocb __user *__user *iocbpp, bool compat)
{
struct kioctx *ctx;
long ret = 0;
int i;
struct hlist_head batch_hash[AIO_BATCH_HASH_SIZE] = { { 0, }, };
if (unlikely(nr < 0))
return -EINVAL;
if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
nr = LONG_MAX/sizeof(*iocbpp);
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, batch_hash, compat);
if (ret)
break;
}
aio_batch_free(batch_hash);
put_ioctx(ctx);
return i ? i : 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.
*/
SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
struct iocb __user * __user *, iocbpp)
{
return do_io_submit(ctx_id, nr, iocbpp, 0);
}
/* lookup_kiocb
* Finds a given iocb for cancellation.
*/
static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
u32 key)
{
struct list_head *pos;
assert_spin_locked(&ctx->ctx_lock);
/* 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.
*/
SYSCALL_DEFINE3(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. If
* it succeeds, the number of read events is returned. May fail with
* -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
* out of range, if timeout is out of range. May fail with -EFAULT
* if any of the memory specified is invalid. May return 0 or
* < min_nr if the timeout specified by timeout has elapsed
* before sufficient events are available, where timeout == NULL
* specifies an infinite timeout. Note that the timeout pointed to by
* timeout is relative and will be updated if not NULL and the
* operation blocks. Will fail with -ENOSYS if not implemented.
*/
SYSCALL_DEFINE5(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))
ret = read_events(ioctx, min_nr, nr, events, timeout);
put_ioctx(ioctx);
}
asmlinkage_protect(5, ret, ctx_id, min_nr, nr, events, timeout);
return ret;
}
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