[PATCH] ext4 balloc: reset windowsz when full

ext4_new_blocks should reset the reservation window size to 0 when squeezing
the last blocks out of an almost full filesystem, so the retry doesn't skip
any groups with less than half that free, reporting ENOSPC too soon.

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>

fs/ext4/balloc.c

@@ -1566,6 +1566,7 @@ retry_alloc:
 	 */
 	if (my_rsv) {
 		my_rsv = NULL;
+		windowsz = 0;
 		group_no = goal_group;
 		goto retry_alloc;
 	}