splice: remove i_mutex locking in splice_from_pipe() (2933970b) · Commits · 戴 / test

fs/splice.c

+2 −16

Original line number	Diff line number	Diff line
		@@ -784,7 +784,7 @@ EXPORT_SYMBOL(__splice_from_pipe);
		* @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 @@ ssize_t splice_from_pipe(struct pipe_inode_info pipe, struct file out,
		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 @@ ssize_t splice_from_pipe(struct pipe_inode_info pipe, struct file out,
		.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;
		}