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ext4: Clean up s_dirt handling

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We don't need to set s_dirt in most of the ext4 code when journaling
is enabled.  In ext3/4 some of the summary statistics for # of free
inodes, blocks, and directories are calculated from the per-block
group statistics when the file system is mounted or unmounted.  As a
result the superblock doesn't have to be updated, either via the
journal or by setting s_dirt.  There are a few exceptions, most
notably when resizing the file system, where the superblock needs to
be modified --- and in that case it should be done as a journalled
operation if possible, and s_dirt set only in no-journal mode.

This patch will optimize out some unneeded disk writes when using ext4
with a journal.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o
2010-06-11 23:14:04 -04:00
parent 7e27d6e778
commit a0375156ca
9 changed files with 36 additions and 16 deletions
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16
fs/ext4/ext4_jbd2.c
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@ -143,3 +143,19 @@ int __ext4_handle_dirty_metadata(const char *where, handle_t *handle,
}
return err;
}
int __ext4_handle_dirty_super(const char *where, handle_t *handle,
struct super_block *sb)
{
struct buffer_head *bh = EXT4_SB(sb)->s_sbh;
int err = 0;
if (ext4_handle_valid(handle)) {
err = jbd2_journal_dirty_metadata(handle, bh);
if (err)
ext4_journal_abort_handle(where, __func__, bh,
handle, err);
} else
sb->s_dirt = 1;
return err;
}