Re: [PATCH] 2.5.x write_super is not for syncing

[Andrew Morton <akpm@digeo.com>]

Andrew Morton wrote:
> 
> These two patches are what I'll be testing tonight for 2.5.
> 

I don't feel inclined to take on the whole sync thing at present.
So a minimal fix for this problem is as follows.  Against 2.4.20:

 fs/buffer.c        |    2 ++
 fs/super.c         |    4 ++++
 include/linux/fs.h |    1 +
 3 files changed, 7 insertions(+)

--- linux-akpm/fs/buffer.c~commit-fs	Mon Dec  2 18:40:03 2002
+++ linux-akpm-akpm/fs/buffer.c	Mon Dec  2 18:41:34 2002
@@ -327,6 +327,8 @@ int fsync_super(struct super_block *sb)
 	lock_super(sb);
 	if (sb->s_dirt && sb->s_op && sb->s_op->write_super)
 		sb->s_op->write_super(sb);
+	if (sb->s_op && sb->s_op->sync_fs)
+		sb->s_op->sync_fs(sb);
 	unlock_super(sb);
 	unlock_kernel();
 
--- linux-akpm/include/linux/fs.h~commit-fs	Mon Dec  2 18:40:23 2002
+++ linux-akpm-akpm/include/linux/fs.h	Mon Dec  2 18:40:56 2002
@@ -894,6 +894,7 @@ struct super_operations {
 	void (*delete_inode) (struct inode *);
 	void (*put_super) (struct super_block *);
 	void (*write_super) (struct super_block *);
+	int (*sync_fs) (struct super_block *);
 	void (*write_super_lockfs) (struct super_block *);
 	void (*unlockfs) (struct super_block *);
 	int (*statfs) (struct super_block *, struct statfs *);
--- linux-akpm/fs/super.c~commit-fs	Mon Dec  2 18:44:01 2002
+++ linux-akpm-akpm/fs/super.c	Mon Dec  2 18:44:07 2002
@@ -454,6 +454,8 @@ void sync_supers(kdev_t dev)
 		if (sb) {
 			if (sb->s_dirt)
 				write_super(sb);
+			if (sb->s_op && sb->s_op->sync_fs)
+				sb->s_op->sync_fs(sb);
 			drop_super(sb);
 		}
 		return;
@@ -467,6 +469,8 @@ restart:
 			spin_unlock(&sb_lock);
 			down_read(&sb->s_umount);
 			write_super(sb);
+			if (sb->s_op && sb->s_op->sync_fs)
+				sb->s_op->sync_fs(sb);
 			drop_super(sb);
 			goto restart;
 		} else

_

and

 fs/ext3/super.c |   25 +++++++++++++------------
 1 files changed, 13 insertions(+), 12 deletions(-)

--- linux-akpm/fs/ext3/super.c~ext3_sync_fs	Mon Dec  2 18:45:10 2002
+++ linux-akpm-akpm/fs/ext3/super.c	Mon Dec  2 18:46:59 2002
@@ -47,6 +47,8 @@ static void ext3_mark_recovery_complete(
 static void ext3_clear_journal_err(struct super_block * sb,
 				   struct ext3_super_block * es);
 
+static int ext3_sync_fs(struct super_block * sb);
+
 #ifdef CONFIG_JBD_DEBUG
 int journal_no_write[2];
 
@@ -454,6 +456,7 @@ static struct super_operations ext3_sops
 	delete_inode:	ext3_delete_inode,	/* BKL not held.  We take it */
 	put_super:	ext3_put_super,		/* BKL held */
 	write_super:	ext3_write_super,	/* BKL held */
+	sync_fs:	ext3_sync_fs,
 	write_super_lockfs: ext3_write_super_lockfs, /* BKL not held. Take it */
 	unlockfs:	ext3_unlockfs,		/* BKL not held.  We take it */
 	statfs:		ext3_statfs,		/* BKL held */
@@ -1577,24 +1580,22 @@ int ext3_force_commit(struct super_block
  * This implicitly triggers the writebehind on sync().
  */
 
-static int do_sync_supers = 0;
-MODULE_PARM(do_sync_supers, "i");
-MODULE_PARM_DESC(do_sync_supers, "Write superblocks synchronously");
-
 void ext3_write_super (struct super_block * sb)
 {
+	if (down_trylock(&sb->s_lock) == 0)
+		BUG();
+	sb->s_dirt = 0;
+	log_start_commit(EXT3_SB(sb)->s_journal, NULL);
+}
+
+static int ext3_sync_fs(struct super_block *sb)
+{
 	tid_t target;
 	
-	if (down_trylock(&sb->s_lock) == 0)
-		BUG();		/* aviro detector */
 	sb->s_dirt = 0;
 	target = log_start_commit(EXT3_SB(sb)->s_journal, NULL);
-
-	if (do_sync_supers) {
-		unlock_super(sb);
-		log_wait_commit(EXT3_SB(sb)->s_journal, target);
-		lock_super(sb);
-	}
+	log_wait_commit(EXT3_SB(sb)->s_journal, target);
+	return 0;
 }
 
 /*

_