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@xxxxxxxxxx>
---
fs/btrfs/extent_map.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index d386cfb..a8b7e24 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -550,17 +550,23 @@ int btrfs_add_extent_mapping(struct extent_map_tree *em_tree,
*em_in = existing;
ret = 0;
} else {
+ u64 orig_start = em->start;
+ u64 orig_len = em->len;
+
/*
* The existing extent map is the one nearest to
* the [start, start + len) range which overlaps
*/
ret = merge_extent_mapping(em_tree, existing,
em, start, len);
- free_extent_map(existing);
if (ret) {
free_extent_map(em);
*em_in = NULL;
+ WARN_ONCE(ret, KERN_INFO "Unexpected error %d: merge existing(start %llu len %llu) with em(start %llu len %llu)\n",
+ ret, existing->start, existing->len,
+ orig_start, orig_len);
}
+ free_extent_map(existing);
}
}
--
2.9.4
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