From: Artem Bityutskiy Subject: [PATCHv4 3/5] ext4: remove unnecessary superblock dirtying Date: Wed, 4 Jul 2012 15:21:52 +0300 Message-ID: <1341404514-13660-4-git-send-email-dedekind1@gmail.com> References: <1341404514-13660-1-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: <1341404514-13660-1-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 is used by ext4 to update the superblock via the journal 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. 4. When adding or deleting an orphan (because we update the 's_last_orphan' superblock field). This function, however, falls back to just marking the superblock as dirty if the file-system has no journal. This means that we delay the actual superblock I/O submission by 5 seconds (roughly speaking). Namely, the 'sync_supers()' kernel thread will call 'ext4_write_super()' later, where we actually will submit the superblock down to the media. However: 1. For cases 1-3 it does not add any value to delay the I/O submission. These events are rare and we may just commit submit the superblock for asynchronous I/O right away. 2. For case 4 - similarly, not terribly frequent event in most of workloads. It should be good enough to just submit asynchronous superblock write-out. 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 --- fs/ext4/ext4.h | 1 + fs/ext4/ext4_jbd2.c | 2 +- fs/ext4/super.c | 5 ++--- 3 files changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 0c4042e..b2439d5 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -2041,6 +2041,7 @@ extern int ext4_superblock_csum_verify(struct super_block *sb, struct ext4_super_block *es); extern void ext4_superblock_csum_set(struct super_block *sb, struct ext4_super_block *es); +extern int ext4_commit_super(struct super_block *sb, int sync); extern void *ext4_kvmalloc(size_t size, gfp_t flags); extern void *ext4_kvzalloc(size_t size, gfp_t flags); extern void ext4_kvfree(void *ptr); diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c index 90f7c2e..27354df 100644 --- a/fs/ext4/ext4_jbd2.c +++ b/fs/ext4/ext4_jbd2.c @@ -156,6 +156,6 @@ int __ext4_handle_dirty_super(const char *where, unsigned int line, (struct ext4_super_block *)bh->b_data); mark_buffer_dirty(bh); } else - sb->s_dirt = 1; + err = ext4_commit_super(sb, 0); return err; } diff --git a/fs/ext4/super.c b/fs/ext4/super.c index eb7aa3e..9b26ba0 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -63,7 +63,6 @@ static struct ext4_features *ext4_feat; static int ext4_load_journal(struct super_block *, struct ext4_super_block *, unsigned long journal_devnum); static int ext4_show_options(struct seq_file *seq, struct dentry *root); -static int ext4_commit_super(struct super_block *sb, int sync); static void ext4_mark_recovery_complete(struct super_block *sb, struct ext4_super_block *es); static void ext4_clear_journal_err(struct super_block *sb, @@ -896,7 +895,7 @@ 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) { @@ -4155,7 +4154,7 @@ static int ext4_load_journal(struct super_block *sb, return 0; } -static int ext4_commit_super(struct super_block *sb, int sync) +int ext4_commit_super(struct super_block *sb, int sync) { struct ext4_super_block *es = EXT4_SB(sb)->s_es; struct buffer_head *sbh = EXT4_SB(sb)->s_sbh; -- 1.7.7.6