From: Arne Jansen <sensille@gmx.net>
Date: Fri, 12 Nov 2010 23:17:56 +0000 (+0000)
Subject: btrfs: Fix early enospc because 'unused' calculated with wrong sign.
X-Git-Tag: v2.6.37-rc4~6^2~19
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=6f33434850ed87dc5e56b60ebbad3d3cf405f296;p=profile%2Fcommon%2Fkernel-common.git

btrfs: Fix early enospc because 'unused' calculated with wrong sign.

'unused' calculated with wrong sign in reserve_metadata_bytes().
This might have lead to unwanted over-reservations.

Signed-off-by: Arne Jansen <sensille@gmx.net>
Reviewed-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
---

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a541bc8..ddaf634 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3413,7 +3413,7 @@ again:
 	 * our reservation.
 	 */
 	if (unused <= space_info->total_bytes) {
-		unused -= space_info->total_bytes;
+		unused = space_info->total_bytes - unused;
 		if (unused >= num_bytes) {
 			if (!reserved)
 				space_info->bytes_reserved += orig_bytes;