Messages in this thread Patch in this message | | | Date | Thu, 14 May 2009 15:33:22 -0700 | From | Greg KH <> | Subject | [patch 47/51] splice: remove i_mutex locking in splice_from_pipe() |
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2.6.29-stable review patch. If anyone has any objections, please let us know.
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From: Miklos Szeredi <miklos@szeredi.hu>
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 <mszeredi@suse.cz> Signed-off-by: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/splice.c | 18 ++---------------- 1 file changed, 2 insertions(+), 16 deletions(-)
--- a/fs/splice.c +++ b/fs/splice.c @@ -783,7 +783,7 @@ 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(). * */ @@ -792,7 +792,6 @@ ssize_t splice_from_pipe(struct pipe_ino splice_actor *actor) { ssize_t ret; - struct inode *inode = out->f_mapping->host; struct splice_desc sd = { .total_len = len, .flags = flags, @@ -800,24 +799,11 @@ ssize_t splice_from_pipe(struct pipe_ino .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; }
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