>From c01c905cf3c4c6304a5ea9836389d9cf0d575884 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 30 Jul 2014 11:49:07 +0200 Subject: [PATCH] ext4: Avoid lock inversion between i_mmap_mutex and transaction start 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