ext4: fix double unlock buffer mess during fs-resize

bh_submit_read() is responsible for unlock bh on endio.  In addition,
we need to use bh_uptodate_or_lock() to avoid races.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 5 insertions, 10 deletions

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 9f821ce39800..f21fdbf5c75d 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -1181,17 +1181,12 @@ static struct buffer_head *ext4_get_bitmap(struct super_block *sb, __u64 block)
         struct buffer_head *bh = sb_getblk(sb, block);
         if (!bh)
                 return NULL;
-
-        if (bitmap_uptodate(bh))
-                return bh;
-
-        lock_buffer(bh);
-        if (bh_submit_read(bh) < 0) {
-                unlock_buffer(bh);
-                brelse(bh);
-                return NULL;
+        if (!bh_uptodate_or_lock(bh)) {
+                if (bh_submit_read(bh) < 0) {
+                        brelse(bh);
+                        return NULL;
+                }
         }
-        unlock_buffer(bh);
 
         return bh;
 }