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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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50
fs/splice.c
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@@ -182,8 +182,7 @@ ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
do_wakeup = 0;
page_nr = 0;
if (pipe->inode)
mutex_lock(&pipe->inode->i_mutex);
pipe_lock(pipe);
for (;;) {
if (!pipe->readers) {
@@ -245,15 +244,13 @@ ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
pipe->waiting_writers--;
}
if (pipe->inode) {
mutex_unlock(&pipe->inode->i_mutex);
pipe_unlock(pipe);
if (do_wakeup) {
smp_mb();
if (waitqueue_active(&pipe->wait))
wake_up_interruptible(&pipe->wait);
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
}
if (do_wakeup) {
smp_mb();
if (waitqueue_active(&pipe->wait))
wake_up_interruptible(&pipe->wait);
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
}
while (page_nr < spd_pages)
@@ -801,11 +798,9 @@ ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
.u.file = out,
};
if (pipe->inode)
mutex_lock(&pipe->inode->i_mutex);
pipe_lock(pipe);
ret = __splice_from_pipe(pipe, &sd, actor);
if (pipe->inode)
mutex_unlock(&pipe->inode->i_mutex);
pipe_unlock(pipe);
return ret;
}
@@ -837,8 +832,7 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
};
ssize_t ret;
if (pipe->inode)
mutex_lock_nested(&pipe->inode->i_mutex, I_MUTEX_PARENT);
pipe_lock(pipe);
splice_from_pipe_begin(&sd);
do {
@@ -854,8 +848,7 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
} while (ret > 0);
splice_from_pipe_end(pipe, &sd);
if (pipe->inode)
mutex_unlock(&pipe->inode->i_mutex);
pipe_unlock(pipe);
if (sd.num_spliced)
ret = sd.num_spliced;
@@ -1348,8 +1341,7 @@ static long vmsplice_to_user(struct file *file, const struct iovec __user *iov,
if (!pipe)
return -EBADF;
if (pipe->inode)
mutex_lock(&pipe->inode->i_mutex);
pipe_lock(pipe);
error = ret = 0;
while (nr_segs) {
@@ -1404,8 +1396,7 @@ static long vmsplice_to_user(struct file *file, const struct iovec __user *iov,
iov++;
}
if (pipe->inode)
mutex_unlock(&pipe->inode->i_mutex);
pipe_unlock(pipe);
if (!ret)
ret = error;
@@ -1533,7 +1524,7 @@ static int link_ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
return 0;
ret = 0;
mutex_lock(&pipe->inode->i_mutex);
pipe_lock(pipe);
while (!pipe->nrbufs) {
if (signal_pending(current)) {
@@ -1551,7 +1542,7 @@ static int link_ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
pipe_wait(pipe);
}
mutex_unlock(&pipe->inode->i_mutex);
pipe_unlock(pipe);
return ret;
}
@@ -1571,7 +1562,7 @@ static int link_opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
return 0;
ret = 0;
mutex_lock(&pipe->inode->i_mutex);
pipe_lock(pipe);
while (pipe->nrbufs >= PIPE_BUFFERS) {
if (!pipe->readers) {
@@ -1592,7 +1583,7 @@ static int link_opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
pipe->waiting_writers--;
}
mutex_unlock(&pipe->inode->i_mutex);
pipe_unlock(pipe);
return ret;
}
@@ -1608,10 +1599,10 @@ static int link_pipe(struct pipe_inode_info *ipipe,
/*
* Potential ABBA deadlock, work around it by ordering lock
* grabbing by inode address. Otherwise two different processes
* grabbing by pipe info address. Otherwise two different processes
* could deadlock (one doing tee from A -> B, the other from B -> A).
*/
inode_double_lock(ipipe->inode, opipe->inode);
pipe_double_lock(ipipe, opipe);
do {
if (!opipe->readers) {
@@ -1662,7 +1653,8 @@ static int link_pipe(struct pipe_inode_info *ipipe,
if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK))
ret = -EAGAIN;
inode_double_unlock(ipipe->inode, opipe->inode);
pipe_unlock(ipipe);
pipe_unlock(opipe);
/*
* If we put data in the output pipe, wakeup any potential readers.