->write_super lock_super pushdown

Push down lock_super into ->write_super instances and remove it from the
caller.

Following filesystem don't need ->s_lock in ->write_super and are skipped:

 * bfs, nilfs2 - no other uses of s_lock and have internal locks in
	->write_super
 * ext2 - uses BKL in ext2_write_super and has internal calls without s_lock
 * reiserfs - no other uses of s_lock as has reiserfs_write_lock (BKL) in
 	->write_super
 * xfs - no other uses of s_lock and uses internal lock (buffer lock on
	superblock buffer) to serialize ->write_super.  Also xfs_fs_write_super
	is superflous and will go away in the next merge window
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/affs/super.c

@@ -54,6 +54,7 @@ affs_write_super(struct super_block *sb)
 	int clean = 2;
 	struct affs_sb_info *sbi = AFFS_SB(sb);
 
+	lock_super(sb);
 	if (!(sb->s_flags & MS_RDONLY)) {
 		//	if (sbi->s_bitmap[i].bm_bh) {
 		//		if (buffer_dirty(sbi->s_bitmap[i].bm_bh)) {
@@ -66,6 +67,7 @@ affs_write_super(struct super_block *sb)
 		sb->s_dirt = !clean;	/* redo until bitmap synced */
 	} else
 		sb->s_dirt = 0;
+	unlock_super(sb);
 
 	pr_debug("AFFS: write_super() at %lu, clean=%d\n", get_seconds(), clean);
 }

fs/exofs/super.c

@@ -214,6 +214,7 @@ static void exofs_write_super(struct super_block *sb)
 		return;
 	}
 
+	lock_super(sb);
 	lock_kernel();
 	sbi = sb->s_fs_info;
 	fscb->s_nextid = cpu_to_le64(sbi->s_nextid);
@@ -246,6 +247,7 @@ out:
 	if (or)
 		osd_end_request(or);
 	unlock_kernel();
+	unlock_super(sb);
 	kfree(fscb);
 }
 

fs/ext4/super.c

@@ -579,7 +579,7 @@ static void ext4_put_super(struct super_block *sb)
 	lock_super(sb);
 	lock_kernel();
 	if (sb->s_dirt)
-		ext4_write_super(sb);
+		ext4_commit_super(sb, 1);
 
 	ext4_release_system_zone(sb);
 	ext4_mb_release(sb);
@@ -3336,7 +3336,9 @@ int ext4_force_commit(struct super_block *sb)
 
 static void ext4_write_super(struct super_block *sb)
 {
+	lock_super(sb);
 	ext4_commit_super(sb, 1);
+	unlock_super(sb);
 }
 
 static int ext4_sync_fs(struct super_block *sb, int wait)

fs/fat/inode.c

@@ -441,10 +441,12 @@ static void fat_clear_inode(struct inode *inode)
 
 static void fat_write_super(struct super_block *sb)
 {
+	lock_super(sb);
 	sb->s_dirt = 0;
 
 	if (!(sb->s_flags & MS_RDONLY))
 		fat_clusters_flush(sb);
+	unlock_super(sb);
 }
 
 static void fat_put_super(struct super_block *sb)

fs/hfs/super.c

@@ -49,11 +49,13 @@ MODULE_LICENSE("GPL");
  */
 static void hfs_write_super(struct super_block *sb)
 {
+	lock_super(sb);
 	sb->s_dirt = 0;
-	if (sb->s_flags & MS_RDONLY)
-		return;
+
 	/* sync everything to the buffers */
+	if (!(sb->s_flags & MS_RDONLY))
 		hfs_mdb_commit(sb);
+	unlock_super(sb);
 }
 
 /*

fs/hfsplus/super.c

@@ -157,10 +157,12 @@ static void hfsplus_write_super(struct super_block *sb)
 	struct hfsplus_vh *vhdr = HFSPLUS_SB(sb).s_vhdr;
 
 	dprint(DBG_SUPER, "hfsplus_write_super\n");
+
+	lock_super(sb);
 	sb->s_dirt = 0;
 	if (sb->s_flags & MS_RDONLY)
 		/* warn? */
-		return;
+		goto out;
 
 	vhdr->free_blocks = cpu_to_be32(HFSPLUS_SB(sb).free_blocks);
 	vhdr->next_alloc = cpu_to_be32(HFSPLUS_SB(sb).next_alloc);
@@ -192,6 +194,8 @@ static void hfsplus_write_super(struct super_block *sb)
 		}
 		HFSPLUS_SB(sb).flags &= ~HFSPLUS_SB_WRITEBACKUP;
 	}
+ out:
+	unlock_super(sb);
 }
 
 static void hfsplus_put_super(struct super_block *sb)

fs/jffs2/super.c

@@ -56,15 +56,18 @@ static void jffs2_i_init_once(void *foo)
 static void jffs2_write_super(struct super_block *sb)
 {
 	struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
-	sb->s_dirt = 0;
 
-	if (sb->s_flags & MS_RDONLY)
-		return;
+	lock_super(sb);
+	sb->s_dirt = 0;
 
+	if (!(sb->s_flags & MS_RDONLY)) {
 		D1(printk(KERN_DEBUG "jffs2_write_super()\n"));
 		jffs2_garbage_collect_trigger(c);
 		jffs2_erase_pending_blocks(c, 0);
 		jffs2_flush_wbuf_gc(c, 0);
+	}
+
+	unlock_super(sb);
 }
 
 static int jffs2_sync_fs(struct super_block *sb, int wait)

fs/super.c

@@ -420,10 +420,8 @@ restart:
 			spin_unlock(&sb_lock);
 
 			down_read(&sb->s_umount);
-			lock_super(sb);
 			if (sb->s_root && sb->s_dirt)
 				sb->s_op->write_super(sb);
-			unlock_super(sb);
 			up_read(&sb->s_umount);
 
 			spin_lock(&sb_lock);

fs/sync.c

@@ -33,10 +33,8 @@ static int __sync_filesystem(struct super_block *sb, int wait)
 	else
 		sync_quota_sb(sb, -1);
 	sync_inodes_sb(sb, wait);
-	lock_super(sb);
 	if (sb->s_dirt && sb->s_op->write_super)
 		sb->s_op->write_super(sb);
-	unlock_super(sb);
 	if (sb->s_op->sync_fs)
 		sb->s_op->sync_fs(sb, wait);
 	return __sync_blockdev(sb->s_bdev, wait);
@@ -164,10 +162,8 @@ int file_fsync(struct file *filp, struct dentry *dentry, int datasync)
 
 	/* sync the superblock to buffers */
 	sb = inode->i_sb;
-	lock_super(sb);
 	if (sb->s_dirt && sb->s_op->write_super)
 		sb->s_op->write_super(sb);
-	unlock_super(sb);
 
 	/* .. finally sync the buffers to disk */
 	err = sync_blockdev(sb->s_bdev);

fs/sysv/inode.c

@@ -37,6 +37,7 @@ static void sysv_write_super(struct super_block *sb)
 	struct sysv_sb_info *sbi = SYSV_SB(sb);
 	unsigned long time = get_seconds(), old_time;
 
+	lock_super(sb);
 	lock_kernel();
 	if (sb->s_flags & MS_RDONLY)
 		goto clean;
@@ -56,6 +57,7 @@ static void sysv_write_super(struct super_block *sb)
 clean:
 	sb->s_dirt = 0;
 	unlock_kernel();
+	unlock_super(sb);
 }
 
 static int sysv_remount(struct super_block *sb, int *flags, char *data)

fs/ufs/super.c

@@ -1131,6 +1131,7 @@ static void ufs_write_super(struct super_block *sb)
 	struct ufs_super_block_third * usb3;
 	unsigned flags;
 
+	lock_super(sb);
 	lock_kernel();
 	UFSD("ENTER\n");
 	flags = UFS_SB(sb)->s_flags;
@@ -1150,6 +1151,7 @@ static void ufs_write_super(struct super_block *sb)
 	sb->s_dirt = 0;
 	UFSD("EXIT\n");
 	unlock_kernel();
+	unlock_super(sb);
 }
 
 static void ufs_put_super(struct super_block *sb)