From: Liu Bo <bo.li.liu@oracle.com>
Date: Fri, 15 Dec 2017 06:36:53 +0000 (-0700)
Subject: Btrfs: add WARN_ONCE to detect unexpected error from merge_extent_mapping
X-Git-Tag: v4.1.12-124.31.3~1210
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=e2a2af61bf91599257476b10009f21fd8b127613;p=users%2Fjedix%2Flinux-maple.git

Btrfs: add WARN_ONCE to detect unexpected error from merge_extent_mapping

Orabug: 27446668

This is a subtle case, so in order to understand the problem, it'd be
good to know the content of existing and em when any error occurs.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
---

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index e897be1140f5..77f73795ed42 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6964,11 +6964,14 @@ insert:
 			 */
 			err = merge_extent_mapping(em_tree, existing,
 						   em, start);
-			free_extent_map(existing);
 			if (err) {
+				WARN_ONCE(1, "existing (0x%llx 0x%llx 0x%llx) em (0x%llx 0x%llx 0x%llx)\n",
+					  existing->start, existing->len, existing->block_start,
+					  em->start, em->len, em->block_start);
 				free_extent_map(em);
 				em = NULL;
 			}
+			free_extent_map(existing);
 		} else {
 			free_extent_map(em);
 			em = existing;