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    Subject[PATCH v2 3/4] ext4: remove unnecessary superblock dirtying
    From: Artem Bityutskiy <>

    This patch changes the '__ext4_handle_dirty_super()' function which is used
    by ext4 to update the super-block 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

    This function, however, falls back to just marking the superblock as dirty
    if the file-system has no journal. But it is user really rarely and it does not
    give any benefit to use the delayed superblock write (via the VFS's
    'sync_supers()' kernel thread) in these cases. We can just write out the
    superblock asynchronously instead.

    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 aba3749..ba2cf3f 100644
    --- a/fs/ext4/ext4.h
    +++ b/fs/ext4/ext4.h
    @@ -1953,6 +1953,7 @@ extern int ext4_group_extend(struct super_block *sb,
    extern int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count);

    /* super.c */
    +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 aca1790..a85f46f 100644
    --- a/fs/ext4/ext4_jbd2.c
    +++ b/fs/ext4/ext4_jbd2.c
    @@ -149,6 +149,6 @@ int __ext4_handle_dirty_super(const char *where, unsigned int line,
    ext4_journal_abort_handle(where, line, __func__,
    bh, handle, err);
    } 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 ceebaf8..6b45785 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,
    @@ -853,7 +852,7 @@ static void ext4_put_super(struct super_block *sb)
    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) {
    @@ -3991,7 +3990,7 @@ 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;

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      Last update: 2012-04-02 13:49    [W:0.028 / U:5.524 seconds]
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