writeback: fix ntfs with sb_has_dirty_inodes()

NTFS's if-condition on dirty inodes is not complete.  Fix it with
sb_has_dirty_inodes().

Cc: Anton Altaparmakov <aia21@cantab.net>
Cc: Ken Chen <kenchen@google.com>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/fs-writeback.c

@@ -199,6 +199,14 @@ static void queue_io(struct super_block *sb,
 	move_expired_inodes(&sb->s_dirty, &sb->s_io, older_than_this);
 }
 
+int sb_has_dirty_inodes(struct super_block *sb)
+{
+	return !list_empty(&sb->s_dirty) ||
+	       !list_empty(&sb->s_io) ||
+	       !list_empty(&sb->s_more_io);
+}
+EXPORT_SYMBOL(sb_has_dirty_inodes);
+
 /*
  * Write a single inode's dirty pages and inode data out to disk.
  * If `wait' is set, wait on the writeout.
@@ -497,7 +505,7 @@ writeback_inodes(struct writeback_control *wbc)
 restart:
 	sb = sb_entry(super_blocks.prev);
 	for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.prev)) {
-		if (!list_empty(&sb->s_dirty) || !list_empty(&sb->s_io)) {
+		if (sb_has_dirty_inodes(sb)) {
 			/* we're making our own get_super here */
 			sb->s_count++;
 			spin_unlock(&sb_lock);

fs/ntfs/super.c

@@ -2381,14 +2381,14 @@ static void ntfs_put_super(struct super_block *sb)
 	 */
 	ntfs_commit_inode(vol->mft_ino);
 	write_inode_now(vol->mft_ino, 1);
-	if (!list_empty(&sb->s_dirty)) {
+	if (sb_has_dirty_inodes(sb)) {
 		const char *s1, *s2;
 
 		mutex_lock(&vol->mft_ino->i_mutex);
 		truncate_inode_pages(vol->mft_ino->i_mapping, 0);
 		mutex_unlock(&vol->mft_ino->i_mutex);
 		write_inode_now(vol->mft_ino, 1);
-		if (!list_empty(&sb->s_dirty)) {
+		if (sb_has_dirty_inodes(sb)) {
 			static const char *_s1 = "inodes";
 			static const char *_s2 = "";
 			s1 = _s1;

include/linux/fs.h

@@ -1729,6 +1729,7 @@ extern int bdev_read_only(struct block_device *);
 extern int set_blocksize(struct block_device *, int);
 extern int sb_set_blocksize(struct super_block *, int);
 extern int sb_min_blocksize(struct super_block *, int);
+extern int sb_has_dirty_inodes(struct super_block *);
 
 extern int generic_file_mmap(struct file *, struct vm_area_struct *);
 extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *);