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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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