[PATCH] ext3 balloc: fix _with_rsv freeze

Port fix to the off-by-one in find_next_usable_block's memscan from ext2 to
ext3; but it didn't cause a serious problem for ext3 because the additional
ext3_test_allocatable check rescued it from the error.

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/ext3/balloc.c b/fs/ext3/balloc.c
index 5a2c198..2216174 100644 (file)
--- a/fs/ext3/balloc.c
+++ b/fs/ext3/balloc.c
@@ -730,7 +730,7 @@ find_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
                here = 0;
 
        p = ((char *)bh->b_data) + (here >> 3);
                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 && ext3_test_allocatable(next, bh))
        next = (r - ((char *)bh->b_data)) << 3;
 
        if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh))