[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 1c8ef0e..c4dd110 100644 (file)
--- 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))