[PATCH 8/8] ext2: introduce own superblock dirty flag

From: Artem Bityutskiy
Date: Wed Mar 21 2012 - 12:15:25 EST


From: Artem Bityutskiy <artem.bityutskiy@xxxxxxxxxxxxxxx>

We finally do not need VFS's 's_dirt' flag in ext2 - introduce our own
's_dirty' flag instead.

Note: the final goal is to get rid of the 'sync_supers()' kernel thread which
wakes up every 5 seconds and even if there is nothing to do. Thus, we are
pushing superblock management from VFS down to file-systems.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@xxxxxxxxxxxxxxx>
---
fs/ext2/super.c | 16 ++++++++--------
include/linux/ext2_fs_sb.h | 1 +
2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 4eee017..bb12634 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -1162,7 +1162,7 @@ static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es,
{
struct ext2_sb_info *sbi = EXT2_SB(sb);

- sb->s_dirt = 0;
+ sbi->s_dirty = 0;
/*
* Make sure we first mark the superblock as clean and then start
* writing it out.
@@ -1213,7 +1213,7 @@ void ext2_write_super(struct super_block *sb)
if (!(sb->s_flags & MS_RDONLY))
ext2_sync_fs(sb, 1);
else {
- sb->s_dirt = 0;
+ EXT2_SB(sb)->s_dirty = 0;
smp_wmb();
}
}
@@ -1239,7 +1239,7 @@ static void write_super(struct work_struct *work)
kfree(sbwork);

smp_rmb();
- if (sb->s_dirt)
+ if (EXT2_SB(sb)->s_dirty)
return;

ext2_write_super(sb);
@@ -1251,12 +1251,12 @@ void ext2_mark_super_dirty(struct super_block *sb)
struct sb_delayed_work *sbwork;
unsigned long delay;

- /* Make sure we see 's_dirt' changes ASAP */
+ /* Make sure we see 's_dirty' changes ASAP */
smp_rmb();
- if (sb->s_dirt == 1)
+ if (sbi->s_dirty == 1)
return;
- sb->s_dirt = 1;
- /* Make other CPUs see the 's_dirt' change as soon as possible */
+ sbi->s_dirty = 1;
+ /* Make other CPUs see the 's_dirty' change as soon as possible */
smp_wmb();

sbwork = kmalloc(sizeof(struct sb_delayed_work), GFP_NOFS);
@@ -1266,7 +1266,7 @@ void ext2_mark_super_dirty(struct super_block *sb)
* trouble anyway, and the SB will be written out on unmount or
* we may be luckier next time it is marked as dirty.
*/
- sb->s_dirt = 2;
+ sbi->s_dirty = 2;
return;
}

diff --git a/include/linux/ext2_fs_sb.h b/include/linux/ext2_fs_sb.h
index 75aa40e..5938744 100644
--- a/include/linux/ext2_fs_sb.h
+++ b/include/linux/ext2_fs_sb.h
@@ -99,6 +99,7 @@ struct ext2_sb_info {
u32 s_next_generation;
unsigned long s_dir_count;
u8 *s_debts;
+ int s_dirty;
/* workqueue for synchronizing the superblock */
struct workqueue_struct *sync_super_wq;
struct percpu_counter s_freeblocks_counter;
--
1.7.7.6

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