vfs: fix unconditional write_super() call in file_fsync()
We need to check ->s_dirt before calling write_super(). It became the cause
of an unneeded write.
This bug was noticed by Sudhanshu Saxena.
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/sync.c b/fs/sync.c
index 7cd005ea..228e17b 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -64,7 +64,7 @@
/* sync the superblock to buffers */
sb = inode->i_sb;
lock_super(sb);
- if (sb->s_op->write_super)
+ if (sb->s_dirt && sb->s_op->write_super)
sb->s_op->write_super(sb);
unlock_super(sb);
