From dbda7d1d8a375ec42a6f7602263ec854d9fd7245 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 14 Apr 2009 19:48:37 +0200 Subject: [PATCH] splice: remove i_mutex locking in splice_from_pipe() commit 2933970b960223076d6affcf7a77e2bc546b8102 upstream. 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 Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- fs/splice.c | 18 ++---------------- 1 file changed, 2 insertions(+), 16 deletions(-) diff --git a/fs/splice.c b/fs/splice.c index 62d8b0334c518..483fa8cc4bc0d 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -782,7 +782,7 @@ 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(). * */ @@ -791,7 +791,6 @@ 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, @@ -799,24 +798,11 @@ ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, .u.file = out, }; - /* - * The actor worker might be calling ->prepare_write and - * ->commit_write. 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; } -- 2.47.3