@@ -110,33 +110,33 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
!(sb->s_flags & MS_RDONLY))) {
sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
/*
* Sample where the filesystem has been mounted and
* store it in the superblock for sysadmin convenience
* when trying to sort through large numbers of block
* devices or filesystem images.
*/
memset(buf, 0, sizeof(buf));
path.mnt = mnt;
path.dentry = mnt->mnt_root;
cp = d_path(&path, buf, sizeof(buf));
if (!IS_ERR(cp)) {
memcpy(sbi->s_es->s_last_mounted, cp,
sizeof(sbi->s_es->s_last_mounted));
- sb->s_dirt = 1;
+ ext4_mark_super_dirty(sb);
}
As I read this, it means that if do have journal, do not bother writing
out the updated superblock at all. When the superblock will be written
out then?
Thanks!
P.S. The reason I look at this is because I am trying to make sure ext4
does not use s_dirty and does not rely on VFS calling 'write_super()' at
all. I guess I will try to use a delayed work instead and move 's_dirt'
to sbi. The reason of this exercise is that I want to eliminate
'sync_supers()' completely, because it wakes up every 5 seconds no
matter what, and Al wanted me to push SB handling down to file-systems.
--
Best Regards,
Hi Ted, could you please commend on this commit of yours a bit: commit a0375156ca1041574b5d47cc7e32f10b891151b0 Author: Theodore Ts'o <tytso@mit.edu> Date: Fri Jun 11 23:14:04 2010 -0400 ext4: Clean up s_dirt handling 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> Let's take this hunk (I preserved more context than usual) Artem Bityutskiy