Merge tag 'writeback-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux

Pull writeback fix from Wu Fengguang:
 "A trivial writeback fix"

* tag 'writeback-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux:
  writeback: Do not sort b_io list only because of block device inode

2 files changed, 6 insertions, 4 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index c3549ed58038..1e86823a9cbd 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -592,7 +592,7 @@ static struct block_device *bd_acquire(struct inode *inode)
         return bdev;
 }
 
-static inline int sb_is_blkdev_sb(struct super_block *sb)
+int sb_is_blkdev_sb(struct super_block *sb)
 {
         return sb == blockdev_superblock;
 }
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 30f6f27d5a59..9f4935b8f208 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -69,7 +69,7 @@ static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
 {
         struct super_block *sb = inode->i_sb;
 
-        if (strcmp(sb->s_type->name, "bdev") == 0)
+        if (sb_is_blkdev_sb(sb))
                 return inode->i_mapping->backing_dev_info;
 
         return sb->s_bdi;
@@ -251,11 +251,13 @@ static int move_expired_inodes(struct list_head *delaying_queue,
                 if (work->older_than_this &&
                     inode_dirtied_after(inode, *work->older_than_this))
                         break;
+                list_move(&inode->i_wb_list, &tmp);
+                moved++;
+                if (sb_is_blkdev_sb(inode->i_sb))
+                        continue;
                 if (sb && sb != inode->i_sb)
                         do_sb_sort = 1;
                 sb = inode->i_sb;
-                list_move(&inode->i_wb_list, &tmp);
-                moved++;
         }
 
         /* just one sb in list, splice to dispatch_queue and we're done */