From: Artem Bityutskiy <artem.bityutskiy@xxxxxxxxxxxxxxx>
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 <artem.bityutskiy@xxxxxxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
---
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
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