From: Jan Kara Subject: [PATCH] ext4: Avoid lock inversion between i_mmap_mutex and transaction start Date: Fri, 10 Oct 2014 16:23:13 +0200 Message-ID: <1412951028-4085-9-git-send-email-jack@suse.cz> References: <1412951028-4085-1-git-send-email-jack@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Dave Kleikamp , jfs-discussion@lists.sourceforge.net, tytso@mit.edu, Jeff Mahoney , Mark Fasheh , Dave Chinner , reiserfs-devel@vger.kernel.org, xfs@oss.sgi.com, cluster-devel@redhat.com, Jan Kara , linux-ext4@vger.kernel.org, Steven Whitehouse , ocfs2-devel@oss.oracle.com, viro@zeniv.linux.org.uk To: linux-fsdevel@vger.kernel.org Return-path: In-Reply-To: <1412951028-4085-1-git-send-email-jack@suse.cz> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: ocfs2-devel-bounces@oss.oracle.com Errors-To: ocfs2-devel-bounces@oss.oracle.com List-Id: linux-ext4.vger.kernel.org When DAX is enabled, it uses i_mmap_mutex as a protection against truncate during page fault. This inevitably forces i_mmap_mutex to rank outside of a transaction start and thus we have to avoid calling pagecache purging operations when transaction is started. Signed-off-by: Jan Kara --- fs/ext4/inode.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 8a064734e6eb..494a8645d63e 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3631,13 +3631,19 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length) if (IS_SYNC(inode)) ext4_handle_sync(handle); - /* Now release the pages again to reduce race window */ + inode->i_mtime = inode->i_ctime = ext4_current_time(inode); + ext4_mark_inode_dirty(handle, inode); + ext4_journal_stop(handle); + + /* + * Now release the pages again to reduce race window. This has to happen + * outside of a transaction to avoid lock inversion on i_mmap_mutex + * when DAX is enabled. + */ if (last_block_offset > first_block_offset) truncate_pagecache_range(inode, first_block_offset, last_block_offset); - - inode->i_mtime = inode->i_ctime = ext4_current_time(inode); - ext4_mark_inode_dirty(handle, inode); + goto out_dio; out_stop: ext4_journal_stop(handle); out_dio: -- 1.8.1.4