- 根目录:
- fs
- aio.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.
*/
#define pr_fmt(fmt) "%s: " fmt, __func__
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/time.h>
#include <linux/aio_abi.h>
#include <linux/export.h>
#include <linux/syscalls.h>
#include <linux/backing-dev.h>
#include <linux/uio.h>
#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/compat.h>
#include <asm/kmap_types.h>
#include <asm/uaccess.h>
#define AIO_RING_MAGIC 0xa10a10a1
#define AIO_RING_COMPAT_FEATURES 1
#define AIO_RING_INCOMPAT_FEATURES 0
struct aio_ring {
unsigned id; /* kernel internal index number */
unsigned nr; /* number of io_events */
unsigned head;
unsigned tail;
unsigned magic;
unsigned compat_features;
unsigned incompat_features;
unsigned header_length; /* size of aio_ring */
struct io_event io_events[0];
}; /* 128 bytes + ring size */
#define AIO_RING_PAGES 8
struct kioctx {
atomic_t users;
atomic_t dead;
/* This needs improving */
unsigned long user_id;
struct hlist_node list;
/*
* This is what userspace passed to io_setup(), it's not used for
* anything but counting against the global max_reqs quota.
*
* The real limit is nr_events - 1, which will be larger (see
* aio_setup_ring())
*/
unsigned max_reqs;
/* Size of ringbuffer, in units of struct io_event */
unsigned nr_events;
unsigned long mmap_base;
unsigned long mmap_size;
struct page **ring_pages;
long nr_pages;
struct rcu_head rcu_head;
struct work_struct rcu_work;
struct {
atomic_t reqs_active;
} ____cacheline_aligned_in_smp;
struct {
spinlock_t ctx_lock;
struct list_head active_reqs; /* used for cancellation */
} ____cacheline_aligned_in_smp;
struct {
struct mutex ring_lock;
wait_queue_head_t wait;
} ____cacheline_aligned_in_smp;
struct {
unsigned tail;
spinlock_t completion_lock;
} ____cacheline_aligned_in_smp;
struct page *internal_pages[AIO_RING_PAGES];
};
/*------ 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;
/* 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);
pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
return 0;
}
__initcall(aio_setup);
static void aio_free_ring(struct kioctx *ctx)
{
long i;
for (i = 0; i < ctx->nr_pages; i++)
put_page(ctx->ring_pages[i]);
if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages)
kfree(ctx->ring_pages);
}
static int aio_setup_ring(struct kioctx *ctx)
{
struct aio_ring *ring;
unsigned nr_events = ctx->max_reqs;
struct mm_struct *mm = current->mm;
unsigned long size, populate;
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);
ctx->nr_events = 0;
ctx->ring_pages = ctx->internal_pages;
if (nr_pages > AIO_RING_PAGES) {
ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
GFP_KERNEL);
if (!ctx->ring_pages)
return -ENOMEM;
}
ctx->mmap_size = nr_pages * PAGE_SIZE;
pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
down_write(&mm->mmap_sem);
ctx->mmap_base = do_mmap_pgoff(NULL, 0, ctx->mmap_size,
PROT_READ|PROT_WRITE,
MAP_ANONYMOUS|MAP_PRIVATE, 0, &populate);
if (IS_ERR((void *)ctx->mmap_base)) {
up_write(&mm->mmap_sem);
ctx->mmap_size = 0;
aio_free_ring(ctx);
return -EAGAIN;
}
pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
ctx->nr_pages = get_user_pages(current, mm, ctx->mmap_base, nr_pages,
1, 0, ctx->ring_pages, NULL);
up_write(&mm->mmap_sem);
if (unlikely(ctx->nr_pages != nr_pages)) {
aio_free_ring(ctx);
return -EAGAIN;
}
if (populate)
mm_populate(ctx->mmap_base, populate);
ctx->user_id = ctx->mmap_base;
ctx->nr_events = nr_events; /* trusted copy */
ring = kmap_atomic(ctx->ring_pages[0]);
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);
flush_dcache_page(ctx->ring_pages[0]);
return 0;
}
#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)
void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel)
{
struct kioctx *ctx = req->ki_ctx;
unsigned long flags;
spin_lock_irqsave(&ctx->ctx_lock, flags);
if (!req->ki_list.next)
list_add(&req->ki_list, &ctx->active_reqs);
req->ki_cancel = cancel;
spin_unlock_irqrestore(&ctx->ctx_lock, flags);
}
EXPORT_SYMBOL(kiocb_set_cancel_fn);
static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb,
struct io_event *res)
{
kiocb_cancel_fn *old, *cancel;
int ret = -EINVAL;
/*
* Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
* actually has a cancel function, hence the cmpxchg()
*/
cancel = ACCESS_ONCE(kiocb->ki_cancel);
do {
if (!cancel || cancel == KIOCB_CANCELLED)
return ret;
old = cancel;
cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
} while (cancel != old);
atomic_inc(&kiocb->ki_users);
spin_unlock_irq(&ctx->ctx_lock);
memset(res, 0, sizeof(*res));
res->obj = (u64)(unsigned long)kiocb->ki_obj.user;
res->data = kiocb->ki_user_data;
ret = cancel(kiocb, res);
spin_lock_irq(&ctx->ctx_lock);
return ret;
}
static void free_ioctx_rcu(struct rcu_head *head)
{
struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
kmem_cache_free(kioctx_cachep, ctx);
}
/*
* When this function runs, the kioctx has been removed from the "hash table"
* and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
* now it's safe to cancel any that need to be.
*/
static void free_ioctx(struct kioctx *ctx)
{
struct aio_ring *ring;
struct io_event res;
struct kiocb *req;
unsigned head, avail;
spin_lock_irq(&ctx->ctx_lock);
while (!list_empty(&ctx->active_reqs)) {
req = list_first_entry(&ctx->active_reqs,
struct kiocb, ki_list);
list_del_init(&req->ki_list);
kiocb_cancel(ctx, req, &res);
}
spin_unlock_irq(&ctx->ctx_lock);
ring = kmap_atomic(ctx->ring_pages[0]);
head = ring->head;
kunmap_atomic(ring);
while (atomic_read(&ctx->reqs_active) > 0) {
wait_event(ctx->wait,
head != ctx->tail ||
atomic_read(&ctx->reqs_active) <= 0);
avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head;
atomic_sub(avail, &ctx->reqs_active);
head += avail;
head %= ctx->nr_events;
}
WARN_ON(atomic_read(&ctx->reqs_active) < 0);
aio_free_ring(ctx);
pr_debug("freeing %p\n", ctx);
/*
* Here the call_rcu() is between the wait_event() for reqs_active to
* hit 0, and freeing the ioctx.
*
* aio_complete() decrements reqs_active, but it has to touch the ioctx
* after to issue a wakeup so we use rcu.
*/
call_rcu(&ctx->rcu_head, free_ioctx_rcu);
}
static void put_ioctx(struct kioctx *ctx)
{
if (unlikely(atomic_dec_and_test(&ctx->users)))
free_ioctx(ctx);
}
/* 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 = current->mm;
struct kioctx *ctx;
int err = -ENOMEM;
/* 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 || (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;
atomic_set(&ctx->users, 2);
atomic_set(&ctx->dead, 0);
spin_lock_init(&ctx->ctx_lock);
spin_lock_init(&ctx->completion_lock);
mutex_init(&ctx->ring_lock);
init_waitqueue_head(&ctx->wait);
INIT_LIST_HEAD(&ctx->active_reqs);
if (aio_setup_ring(ctx) < 0)
goto out_freectx;
/* limit the number of system wide aios */
spin_lock(&aio_nr_lock);
if (aio_nr + nr_events > aio_max_nr ||
aio_nr + nr_events < aio_nr) {
spin_unlock(&aio_nr_lock);
goto out_cleanup;
}
aio_nr += ctx->max_reqs;
spin_unlock(&aio_nr_lock);
/* now link into global list. */
spin_lock(&mm->ioctx_lock);
hlist_add_head_rcu(&ctx->list, &mm->ioctx_list);
spin_unlock(&mm->ioctx_lock);
pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
ctx, ctx->user_id, mm, ctx->nr_events);
return ctx;
out_cleanup:
err = -EAGAIN;
aio_free_ring(ctx);
out_freectx:
kmem_cache_free(kioctx_cachep, ctx);
pr_debug("error allocating ioctx %d\n", err);
return ERR_PTR(err);
}
static void kill_ioctx_work(struct work_struct *work)
{
struct kioctx *ctx = container_of(work, struct kioctx, rcu_work);
wake_up_all(&ctx->wait);
put_ioctx(ctx);
}
static void kill_ioctx_rcu(struct rcu_head *head)
{
struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
INIT_WORK(&ctx->rcu_work, kill_ioctx_work);
schedule_work(&ctx->rcu_work);
}
/* kill_ioctx
* 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 kill_ioctx(struct kioctx *ctx)
{
if (!atomic_xchg(&ctx->dead, 1)) {
hlist_del_rcu(&ctx->list);
/*
* It'd be more correct to do this in free_ioctx(), after all
* the outstanding kiocbs have finished - but by then io_destroy
* has already returned, so io_setup() could potentially return
* -EAGAIN with no ioctxs actually in use (as far as userspace
* could tell).
*/
spin_lock(&aio_nr_lock);
BUG_ON(aio_nr - ctx->max_reqs > aio_nr);
aio_nr -= ctx->max_reqs;
spin_unlock(&aio_nr_lock);
if (ctx->mmap_size)
vm_munmap(ctx->mmap_base, ctx->mmap_size);
/* Between hlist_del_rcu() and dropping the initial ref */
call_rcu(&ctx->rcu_head, kill_ioctx_rcu);
}
}
/* wait_on_sync_kiocb:
* Waits on the given sync kiocb to complete.
*/
ssize_t wait_on_sync_kiocb(struct kiocb *iocb)
{
while (atomic_read(&iocb->ki_users)) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (!atomic_read(&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.
*
* There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
* them.
*/
void exit_aio(struct mm_struct *mm)
{
struct kioctx *ctx;
struct hlist_node *n;
hlist_for_each_entry_safe(ctx, n, &mm->ioctx_list, list) {
if (1 != atomic_read(&ctx->users))
printk(KERN_DEBUG
"exit_aio:ioctx still alive: %d %d %d\n",
atomic_read(&ctx->users),
atomic_read(&ctx->dead),
atomic_read(&ctx->reqs_active));
/*
* We don't need to bother with munmap() here -
* exit_mmap(mm) is coming and it'll unmap everything.
* Since aio_free_ring() uses non-zero ->mmap_size
* as indicator that it needs to unmap the area,
* just set it to 0; aio_free_ring() is the only
* place that uses ->mmap_size, so it's safe.
*/
ctx->mmap_size = 0;
kill_ioctx(ctx);
}
}
/* aio_get_req
* Allocate a slot for an aio request. Increments the ki_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->ki_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 inline struct kiocb *aio_get_req(struct kioctx *ctx)
{
struct kiocb *req;
if (atomic_read(&ctx->reqs_active) >= ctx->nr_events)
return NULL;
if (atomic_inc_return(&ctx->reqs_active) > ctx->nr_events - 1)
goto out_put;
req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
if (unlikely(!req))
goto out_put;
atomic_set(&req->ki_users, 2);
req->ki_ctx = ctx;
return req;
out_put:
atomic_dec(&ctx->reqs_active);
return NULL;
}
static void kiocb_free(struct kiocb *req)
{
if (req->ki_filp)
fput(req->ki_filp);
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);
}
void aio_put_req(struct kiocb *req)
{
if (atomic_dec_and_test(&req->ki_users))
kiocb_free(req);
}
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;
rcu_read_lock();
hlist_for_each_entry_rcu(ctx, &mm->ioctx_list, list) {
if (ctx->user_id == ctx_id) {
atomic_inc(&ctx->users);
ret = ctx;
break;
}
}
rcu_read_unlock();
return ret;
}
/* aio_complete
* Called when the io request on the given iocb is complete.
*/
void aio_complete(struct kiocb *iocb, long res, long res2)
{
struct kioctx *ctx = iocb->ki_ctx;
struct aio_ring *ring;
struct io_event *ev_page, *event;
unsigned long flags;
unsigned tail, pos;
/*
* 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(atomic_read(&iocb->ki_users) != 1);
iocb->ki_user_data = res;
atomic_set(&iocb->ki_users, 0);
wake_up_process(iocb->ki_obj.tsk);
return;
}
/*
* Take rcu_read_lock() in case the kioctx is being destroyed, as we
* need to issue a wakeup after decrementing reqs_active.
*/
rcu_read_lock();
if (iocb->ki_list.next) {
unsigned long flags;
spin_lock_irqsave(&ctx->ctx_lock, flags);
list_del(&iocb->ki_list);
spin_unlock_irqrestore(&ctx->ctx_lock, flags);
}
/*
* cancelled requests don't get events, userland was given one
* when the event got cancelled.
*/
if (unlikely(xchg(&iocb->ki_cancel,
KIOCB_CANCELLED) == KIOCB_CANCELLED)) {
atomic_dec(&ctx->reqs_active);
/* Still need the wake_up in case free_ioctx is waiting */
goto put_rq;
}
/*
* 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->completion_lock, flags);
tail = ctx->tail;
pos = tail + AIO_EVENTS_OFFSET;
if (++tail >= ctx->nr_events)
tail = 0;
ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
event = ev_page + pos % AIO_EVENTS_PER_PAGE;
event->obj = (u64)(unsigned long)iocb->ki_obj.user;
event->data = iocb->ki_user_data;
event->res = res;
event->res2 = res2;
kunmap_atomic(ev_page);
flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
pr_debug("%p[%u]: %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 */
ctx->tail = tail;
ring = kmap_atomic(ctx->ring_pages[0]);
ring->tail = tail;
kunmap_atomic(ring);
flush_dcache_page(ctx->ring_pages[0]);
spin_unlock_irqrestore(&ctx->completion_lock, flags);
pr_debug("added to ring %p at [%u]\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. */
aio_put_req(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);
rcu_read_unlock();
}
EXPORT_SYMBOL(aio_complete);
/* aio_read_events
* Pull an event off of the ioctx's event ring. Returns the number of
* events fetched
*/
static long aio_read_events_ring(struct kioctx *ctx,
struct io_event __user *event, long nr)
{
struct aio_ring *ring;
unsigned head, pos;
long ret = 0;
int copy_ret;
mutex_lock(&ctx->ring_lock);
ring = kmap_atomic(ctx->ring_pages[0]);
head = ring->head;
kunmap_atomic(ring);
pr_debug("h%u t%u m%u\n", head, ctx->tail, ctx->nr_events);
if (head == ctx->tail)
goto out;
while (ret < nr) {
long avail;
struct io_event *ev;
struct page *page;
avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head;
if (head == ctx->tail)
break;
avail = min(avail, nr - ret);
avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
pos = head + AIO_EVENTS_OFFSET;
page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
pos %= AIO_EVENTS_PER_PAGE;
ev = kmap(page);
copy_ret = copy_to_user(event + ret, ev + pos,
sizeof(*ev) * avail);
kunmap(page);
if (unlikely(copy_ret)) {
ret = -EFAULT;
goto out;
}
ret += avail;
head += avail;
head %= ctx->nr_events;
}
ring = kmap_atomic(ctx->ring_pages[0]);
ring->head = head;
kunmap_atomic(ring);
flush_dcache_page(ctx->ring_pages[0]);
pr_debug("%li h%u t%u\n", ret, head, ctx->tail);
atomic_sub(ret, &ctx->reqs_active);
out:
mutex_unlock(&ctx->ring_lock);
return ret;
}
static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
struct io_event __user *event, long *i)
{
long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
if (ret > 0)
*i += ret;
if (unlikely(atomic_read(&ctx->dead)))
ret = -EINVAL;
if (!*i)
*i = ret;
return ret < 0 || *i >= min_nr;
}
static long read_events(struct kioctx *ctx, long min_nr, long nr,
struct io_event __user *event,
struct timespec __user *timeout)
{
ktime_t until = { .tv64 = KTIME_MAX };
long ret = 0;
if (timeout) {
struct timespec ts;
if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
return -EFAULT;
until = timespec_to_ktime(ts);
}
/*
* Note that aio_read_events() is being called as the conditional - i.e.
* we're calling it after prepare_to_wait() has set task state to
* TASK_INTERRUPTIBLE.
*
* But aio_read_events() can block, and if it blocks it's going to flip
* the task state back to TASK_RUNNING.
*
* This should be ok, provided it doesn't flip the state back to
* TASK_RUNNING and return 0 too much - that causes us to spin. That
* will only happen if the mutex_lock() call blocks, and we then find
* the ringbuffer empty. So in practice we should be ok, but it's
* something to be aware of when touching this code.
*/
wait_event_interruptible_hrtimeout(ctx->wait,
aio_read_events(ctx, min_nr, nr, event, &ret), until);
if (!ret && signal_pending(current))
ret = -EINTR;
return ret;
}
/* 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)
kill_ioctx(ioctx);
put_ioctx(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)) {
kill_ioctx(ioctx);
put_ioctx(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);
}
typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *,
unsigned long, loff_t);
static ssize_t aio_rw_vect_retry(struct kiocb *iocb, int rw, aio_rw_op *rw_op)
{
struct file *file = iocb->ki_filp;
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
ssize_t ret = 0;
/* This matches the pread()/pwrite() logic */
if (iocb->ki_pos < 0)
return -EINVAL;
if (rw == WRITE)
file_start_write(file);
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 &&
(rw == WRITE ||
(!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))));
if (rw == WRITE)
file_end_write(file);
/* 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 (rw == WRITE
&& ret < 0 && ret != -EIOCBQUEUED
&& iocb->ki_nbytes - iocb->ki_left)
ret = iocb->ki_nbytes - iocb->ki_left;
return ret;
}
static ssize_t aio_setup_vectored_rw(int rw, struct kiocb *kiocb, bool compat)
{
ssize_t ret;
kiocb->ki_nr_segs = kiocb->ki_nbytes;
#ifdef CONFIG_COMPAT
if (compat)
ret = compat_rw_copy_check_uvector(rw,
(struct compat_iovec __user *)kiocb->ki_buf,
kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec,
&kiocb->ki_iovec);
else
#endif
ret = rw_copy_check_uvector(rw,
(struct iovec __user *)kiocb->ki_buf,
kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec,
&kiocb->ki_iovec);
if (ret < 0)
return ret;
/* ki_nbytes now reflect bytes instead of segs */
kiocb->ki_nbytes = ret;
return 0;
}
static ssize_t aio_setup_single_vector(int rw, struct kiocb *kiocb)
{
if (unlikely(!access_ok(!rw, kiocb->ki_buf, kiocb->ki_nbytes)))
return -EFAULT;
kiocb->ki_iovec = &kiocb->ki_inline_vec;
kiocb->ki_iovec->iov_base = kiocb->ki_buf;
kiocb->ki_iovec->iov_len = kiocb->ki_nbytes;
kiocb->ki_nr_segs = 1;
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_run_iocb(struct kiocb *req, bool compat)
{
struct file *file = req->ki_filp;
ssize_t ret;
int rw;
fmode_t mode;
aio_rw_op *rw_op;
switch (req->ki_opcode) {
case IOCB_CMD_PREAD:
case IOCB_CMD_PREADV:
mode = FMODE_READ;
rw = READ;
rw_op = file->f_op->aio_read;
goto rw_common;
case IOCB_CMD_PWRITE:
case IOCB_CMD_PWRITEV:
mode = FMODE_WRITE;
rw = WRITE;
rw_op = file->f_op->aio_write;
goto rw_common;
rw_common:
if (unlikely(!(file->f_mode & mode)))
return -EBADF;
if (!rw_op)
return -EINVAL;
ret = (req->ki_opcode == IOCB_CMD_PREADV ||
req->ki_opcode == IOCB_CMD_PWRITEV)
? aio_setup_vectored_rw(rw, req, compat)
: aio_setup_single_vector(rw, req);
if (ret)
return ret;
ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
if (ret < 0)
return ret;
req->ki_nbytes = ret;
req->ki_left = ret;
ret = aio_rw_vect_retry(req, rw, rw_op);
break;
case IOCB_CMD_FDSYNC:
if (!file->f_op->aio_fsync)
return -EINVAL;
ret = file->f_op->aio_fsync(req, 1);
break;
case IOCB_CMD_FSYNC:
if (!file->f_op->aio_fsync)
return -EINVAL;
ret = file->f_op->aio_fsync(req, 0);
break;
default:
pr_debug("EINVAL: no operation provided\n");
return -EINVAL;
}
if (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(req, ret, 0);
}
return 0;
}
static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
struct iocb *iocb, bool compat)
{
struct kiocb *req;
ssize_t ret;
/* enforce forwards compatibility on users */
if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
pr_debug("EINVAL: 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;
}
req = aio_get_req(ctx);
if (unlikely(!req))
return -EAGAIN;
req->ki_filp = fget(iocb->aio_fildes);
if (unlikely(!req->ki_filp)) {
ret = -EBADF;
goto out_put_req;
}
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(KIOCB_KEY, &user_iocb->aio_key);
if (unlikely(ret)) {
pr_debug("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_run_iocb(req, compat);
if (ret)
goto out_put_req;
aio_put_req(req); /* drop extra ref to req */
return 0;
out_put_req:
atomic_dec(&ctx->reqs_active);
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 = 0;
struct blk_plug plug;
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: invalid context id\n");
return -EINVAL;
}
blk_start_plug(&plug);
/*
* 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, compat);
if (ret)
break;
}
blk_finish_plug(&plug);
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);
if (key != KIOCB_KEY)
return NULL;
/* 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)
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)
{
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);
kiocb = lookup_kiocb(ctx, iocb, key);
if (kiocb)
ret = kiocb_cancel(ctx, kiocb, &res);
else
ret = -EINVAL;
spin_unlock_irq(&ctx->ctx_lock);
if (!ret) {
/* Cancellation succeeded -- copy the result
* into the user's buffer.
*/
if (copy_to_user(result, &res, sizeof(res)))
ret = -EFAULT;
}
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. 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);
}
return ret;
}