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splice: add helpers for locking pipe inode

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There are lots of sequences like this, especially in splice code:

	if (pipe->inode)
		mutex_lock(&pipe->inode->i_mutex);
	/* do something */
	if (pipe->inode)
		mutex_unlock(&pipe->inode->i_mutex);

so introduce helpers which do the conditional locking and unlocking.
Also replace the inode_double_lock() call with a pipe_double_lock()
helper to avoid spreading the use of this functionality beyond the
pipe code.

This patch is just a cleanup, and should cause no behavioral changes.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Miklos Szeredi 2009-04-14 19:48:41 +02:00 • committed by Jens Axboe
parent f8cc774ce4
commit 61e0d47c33
5 changed files with 64 additions and 72 deletions
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42
fs/pipe.c
View file

@ -37,6 +37,42 @@
* -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
*/
static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass)
{
if (pipe->inode)
mutex_lock_nested(&pipe->inode->i_mutex, subclass);
}
void pipe_lock(struct pipe_inode_info *pipe)
{
/*
* pipe_lock() nests non-pipe inode locks (for writing to a file)
*/
pipe_lock_nested(pipe, I_MUTEX_PARENT);
}
EXPORT_SYMBOL(pipe_lock);
void pipe_unlock(struct pipe_inode_info *pipe)
{
if (pipe->inode)
mutex_unlock(&pipe->inode->i_mutex);
}
EXPORT_SYMBOL(pipe_unlock);
void pipe_double_lock(struct pipe_inode_info *pipe1,
struct pipe_inode_info *pipe2)
{
BUG_ON(pipe1 == pipe2);
if (pipe1 < pipe2) {
pipe_lock_nested(pipe1, I_MUTEX_PARENT);
pipe_lock_nested(pipe2, I_MUTEX_CHILD);
} else {
pipe_lock_nested(pipe2, I_MUTEX_CHILD);
pipe_lock_nested(pipe1, I_MUTEX_PARENT);
}
}
/* Drop the inode semaphore and wait for a pipe event, atomically */
void pipe_wait(struct pipe_inode_info *pipe)
{
@ -47,12 +83,10 @@ void pipe_wait(struct pipe_inode_info *pipe)
* is considered a noninteractive wait:
*/
prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE);
if (pipe->inode)
mutex_unlock(&pipe->inode->i_mutex);
pipe_unlock(pipe);
schedule();
finish_wait(&pipe->wait, &wait);
if (pipe->inode)
mutex_lock(&pipe->inode->i_mutex);
pipe_lock(pipe);
}
static int