From 97f76d3d197f201ac8a8a3ced5b8fef81568e50e Mon Sep 17 00:00:00 2001
From: Nikanth Karthikesan <knikanth@suse.de>
Date: Thu, 2 Apr 2009 16:56:46 -0700
Subject: vfs: check bh->b_blocknr only if BH_Mapped is set

Check bh->b_blocknr only if BH_Mapped is set.

akpm: I doubt if b_blocknr is ever uninitialised here, but it could
conceivably cause a problem if we're doing a lookup for block zero.

Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 fs/buffer.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

(limited to 'fs')

diff --git a/fs/buffer.c b/fs/buffer.c
index f5f8b15a6e40..2963858f0f31 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -199,13 +199,13 @@ __find_get_block_slow(struct block_device *bdev, sector_t block)
 	head = page_buffers(page);
 	bh = head;
 	do {
-		if (bh->b_blocknr == block) {
+		if (!buffer_mapped(bh))
+			all_mapped = 0;
+		else if (bh->b_blocknr == block) {
 			ret = bh;
 			get_bh(bh);
 			goto out_unlock;
 		}
-		if (!buffer_mapped(bh))
-			all_mapped = 0;
 		bh = bh->b_this_page;
 	} while (bh != head);
 
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