From: Hugh Dickins <hugh@veritas.com>
Date: Thu, 7 Dec 2006 04:39:26 +0000 (-0800)
Subject: [PATCH] ext4 balloc: fix _with_rsv freeze
X-Git-Tag: v2.6.20-rc1~145^2^2~85
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=ec0837f230e57afde65db72539e748d2a75abed0;p=linux-2.6-omap-h63xx.git

[PATCH] ext4 balloc: fix _with_rsv freeze

Port fix to the off-by-one in find_next_usable_block's memscan from ext2 to
ext4; but it didn't cause a serious problem for ext4 because the additional
ext4_test_allocatable check rescued it from the error.

[akpm@osdl.org: build fix]
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 1c8ef0e35f4..c4dd1103ccf 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -747,7 +747,7 @@ find_next_usable_block(ext4_grpblk_t start, struct buffer_head *bh,
 		here = 0;
 
 	p = ((char *)bh->b_data) + (here >> 3);
-	r = memscan(p, 0, (maxblocks - here + 7) >> 3);
+	r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
 	next = (r - ((char *)bh->b_data)) << 3;
 
 	if (next < maxblocks && next >= start && ext4_test_allocatable(next, bh))