From: Artem Bityutskiy Subject: [PATCHv7 3/5] ext4: remove unnecessary superblock dirtying Date: Wed, 11 Jul 2012 16:46:42 +0300 Message-ID: <1342014404-14834-4-git-send-email-dedekind1@gmail.com> References: <1342014404-14834-1-git-send-email-dedekind1@gmail.com> Cc: Linux FS Maling List , Linux Kernel Maling List , Ext4 Mailing List To: Theodore Tso , Jan Kara Return-path: In-Reply-To: <1342014404-14834-1-git-send-email-dedekind1@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org From: Artem Bityutskiy 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 Reviewed-by: Jan Kara --- fs/ext4/ext4_jbd2.c | 5 ++--- fs/ext4/super.c | 2 +- 2 files changed, 3 insertions(+), 4 deletions(-) diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c index 90f7c2e..c19ab6a 100644 --- a/fs/ext4/ext4_jbd2.c +++ b/fs/ext4/ext4_jbd2.c @@ -151,11 +151,10 @@ int __ext4_handle_dirty_super(const char *where, unsigned int line, if (err) ext4_journal_abort_handle(where, line, __func__, bh, handle, err); - } else if (now) { + } else { ext4_superblock_csum_set(sb, (struct ext4_super_block *)bh->b_data); mark_buffer_dirty(bh); - } else - sb->s_dirt = 1; + } return err; } diff --git a/fs/ext4/super.c b/fs/ext4/super.c index eb7aa3e..a391c53 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -896,7 +896,7 @@ static void ext4_put_super(struct super_block *sb) EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER); es->s_state = cpu_to_le16(sbi->s_mount_state); } - if (sb->s_dirt || !(sb->s_flags & MS_RDONLY)) + if (!(sb->s_flags & MS_RDONLY)) ext4_commit_super(sb, 1); if (sbi->s_proc) { -- 1.7.7.6