splice: remove i_mutex locking in splice_from_pipe()
splice_from_pipe() is only called from two places:
- generic_splice_sendpage()
- splice_write_null()
Neither of these require i_mutex to be taken on the destination inode.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fs/splice.c b/fs/splice.c
index fd6b278..349576b 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -784,7 +784,7 @@
* @actor: handler that splices the data
*
* Description:
- * See __splice_from_pipe. This function locks the input and output inodes,
+ * See __splice_from_pipe. This function locks the pipe inode,
* otherwise it's identical to __splice_from_pipe().
*
*/
@@ -793,7 +793,6 @@
splice_actor *actor)
{
ssize_t ret;
- struct inode *inode = out->f_mapping->host;
struct splice_desc sd = {
.total_len = len,
.flags = flags,
@@ -801,24 +800,11 @@
.u.file = out,
};
- /*
- * The actor worker might be calling ->write_begin and
- * ->write_end. Most of the time, these expect i_mutex to
- * be held. Since this may result in an ABBA deadlock with
- * pipe->inode, we have to order lock acquiry here.
- *
- * Outer lock must be inode->i_mutex, as pipe_wait() will
- * release and reacquire pipe->inode->i_mutex, AND inode must
- * never be a pipe.
- */
- WARN_ON(S_ISFIFO(inode->i_mode));
- mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);
if (pipe->inode)
- mutex_lock_nested(&pipe->inode->i_mutex, I_MUTEX_CHILD);
+ mutex_lock(&pipe->inode->i_mutex);
ret = __splice_from_pipe(pipe, &sd, actor);
if (pipe->inode)
mutex_unlock(&pipe->inode->i_mutex);
- mutex_unlock(&inode->i_mutex);
return ret;
}