f2fs: skip committing valid superblock

In recovery procedure for superblock, we try to write data of valid
superblock into invalid one for recovery, work should be finished here,
but then still we will write the valid one with its original data.
This operation is not needed. Let's skip doing this unnecessary work.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index d54c54f..a06b0b4 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1043,7 +1043,7 @@
 	return 0;
 }
 
-int f2fs_commit_super(struct f2fs_sb_info *sbi)
+int f2fs_commit_super(struct f2fs_sb_info *sbi, bool recover)
 {
 	struct buffer_head *sbh = sbi->raw_super_buf;
 	sector_t block = sbh->b_blocknr;
@@ -1055,7 +1055,9 @@
 	err = sync_dirty_buffer(sbh);
 
 	sbh->b_blocknr = block;
-	if (err)
+
+	/* if we are in recovery path, skip writing valid superblock */
+	if (recover || err)
 		goto out;
 
 	/* write current valid superblock */
@@ -1289,7 +1291,7 @@
 	/* recover broken superblock */
 	if (recovery && !f2fs_readonly(sb) && !bdev_read_only(sb->s_bdev)) {
 		f2fs_msg(sb, KERN_INFO, "Recover invalid superblock");
-		f2fs_commit_super(sbi);
+		f2fs_commit_super(sbi, true);
 	}
 
 	return 0;