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Commit 9a7e10e7 authored by Liu Bo's avatar Liu Bo Committed by David Sterba
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Btrfs: add WARN_ONCE to detect unexpected error from merge_extent_mapping 



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: default avatarLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent cd77f4f8

fs/btrfs/extent_map.c

+8 −1
Original line number Diff line number Diff line
@@ -562,17 +562,24 @@ 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);

			free_extent_map(existing);

			if (ret) {

				free_extent_map(em);

				*em_in = NULL;

				WARN_ONCE(ret,

"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);

		}

	}