From: Dmitry Monakhov <dmonakhov@openvz.org>
Date: Wed, 26 Sep 2012 03:19:25 +0000 (-0400)
Subject: ext4: fix double unlock buffer mess during fs-resize
X-Git-Tag: firefly_0821_release~3680^2~1747^2~35
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=7f1468d1d50d368097ab13596dc08eaba7eace7f;p=firefly-linux-kernel-4.4.55.git

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>
---

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;
 }