From: Artem Bityutskiy Date: Mon, 23 Jul 2012 00:33:31 +0000 (-0400) Subject: ext4: remove unnecessary superblock dirtying X-Git-Tag: v3.6-rc1~69^2~5 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=58c5873a769987e36265d1523d2aa5bdc18f32bd;p=pandora-kernel.git ext4: remove unnecessary superblock dirtying This patch changes the 'ext4_handle_dirty_super()' function which submits the superblock for I/O in the following cases: 1. When creating the first large file on a file system without EXT4_FEATURE_RO_COMPAT_LARGE_FILE feature. 2. When re-sizing the file-system. 3. When creating an xattr on a file-system without the EXT4_FEATURE_COMPAT_EXT_ATTR feature. If the file-system has journal enabled, the superblock is written via the journal. We do not modify this path. If the file-system has no journal, this function, falls back to just marking the superblock as dirty using the 's_dirt' superblock flag. This means that it delays the actual superblock I/O submission by 5 seconds (default setting). Namely, the 'sync_supers()' kernel thread will call 'ext4_write_super()' later and will actually submit the superblock for I/O. And this is the behavior this patch modifies: we stop using 's_dirt' and just mark the superblock buffer as dirty right away. Indeed, all 3 cases above are extremely rare and it does not add any value to delay the I/O submission for them. Note: 'ext4_handle_dirty_super()' executes '__ext4_handle_dirty_super()' with 'now = 0'. This patch basically makes the 'now' argument unneeded and it will be deleted in one of the next patches. This patch also removes 's_dirt' condition on the unmount path because we never set it anymore, so we should not test it. Tested using xfstests for both journalled and non-journalled ext4. Signed-off-by: Artem Bityutskiy Signed-off-by: "Theodore Ts'o" Reviewed-by: Jan Kara --- Reading git-diff-tree failed