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[PATCH] aio: kiocb locking to serialise retry and cancel 

Implement a per-kiocb lock to serialise retry operations and cancel.  This
is done using wait_on_bit_lock() on the KIF_LOCKED bit of kiocb->ki_flags.
Also, make the cancellation path lock the kiocb and subsequently release
all references to it if the cancel was successful.  This version includes a
fix for the deadlock with __aio_run_iocbs.

Signed-off-by: Benjamin LaHaise <bcrl@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Benjamin LaHaise 2005-09-09 13:02:09 -07:00 committed by Linus Torvalds
parent 8f58202bf6
commit ac0b1bc1ed
1 changed files with 25 additions and 4 deletions
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29
fs/aio.c
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@ -546,6 +546,24 @@ struct kioctx *lookup_ioctx(unsigned long ctx_id)
return ioctx;
}
static int lock_kiocb_action(void *param)
{
schedule();
return 0;
}
static inline void lock_kiocb(struct kiocb *iocb)
{
wait_on_bit_lock(&iocb->ki_flags, KIF_LOCKED, lock_kiocb_action,
TASK_UNINTERRUPTIBLE);
}
static inline void unlock_kiocb(struct kiocb *iocb)
{
kiocbClearLocked(iocb);
wake_up_bit(&iocb->ki_flags, KIF_LOCKED);
}
/*
* use_mm
* Makes the calling kernel thread take on the specified
@ -786,7 +804,9 @@ static int __aio_run_iocbs(struct kioctx *ctx)
* Hold an extra reference while retrying i/o.
*/
iocb->ki_users++; /* grab extra reference */
lock_kiocb(iocb);
aio_run_iocb(iocb);
unlock_kiocb(iocb);
if (__aio_put_req(ctx, iocb)) /* drop extra ref */
put_ioctx(ctx);
}
@ -1527,10 +1547,9 @@ int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
goto out_put_req;
spin_lock_irq(&ctx->ctx_lock);
if (likely(list_empty(&ctx->run_list))) {
aio_run_iocb(req);
} else {
list_add_tail(&req->ki_run_list, &ctx->run_list);
aio_run_iocb(req);
unlock_kiocb(req);
if (!list_empty(&ctx->run_list)) {
/* drain the run list */
while (__aio_run_iocbs(ctx))
;
@ -1661,6 +1680,7 @@ asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb,
if (NULL != cancel) {
struct io_event tmp;
pr_debug("calling cancel\n");
lock_kiocb(kiocb);
memset(&tmp, 0, sizeof(tmp));
tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user;
tmp.data = kiocb->ki_user_data;
@ -1672,6 +1692,7 @@ asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb,
if (copy_to_user(result, &tmp, sizeof(tmp)))
ret = -EFAULT;
}
unlock_kiocb(kiocb);
} else
ret = -EINVAL;