Btrfs: don't BUG_ON() in btrfs_num_copies (fb7669b5) · Commits · 戴 / test

A user sent me a btrfs-image that was panicing because of some corruption. This is because we pass in a bogus value to btrfs_num_copies, and it panics. Instead just return 1. We only call btrfs_num_copies to see if there are other copies to try and read for things, so if we just return 1 it will make the callers exit out with an appropriate error value. Thanks, Signed-off-by:

Josef Bacik <jbacik@fusionio.com>

fs/btrfs/volumes.c

+18 −2

Original line number	Diff line number	Diff line
		@@ -4232,9 +4232,25 @@ int btrfs_num_copies(struct btrfs_fs_info *fs_info, u64 logical, u64 len)
		read_lock(&em_tree->lock);
		em = lookup_extent_mapping(em_tree, logical, len);
		read_unlock(&em_tree->lock);
		BUG_ON(!em);

		BUG_ON(em->start > logical \|\| em->start + em->len < logical);
		/*
		* We could return errors for these cases, but that could get ugly and
		* we'd probably do the same thing which is just not do anything else
		* and exit, so return 1 so the callers don't try to use other copies.
		*/
		if (!em) {
		btrfs_emerg(fs_info, "No mapping for %Lu-%Lu\n", logical,
		logical+len);
		return 1;
		}

		if (em->start > logical \|\| em->start + em->len < logical) {
		btrfs_emerg(fs_info, "Invalid mapping for %Lu-%Lu, got "
		"%Lu-%Lu\n", logical, logical+len, em->start,
		em->start + em->len);
		return 1;
		}

		map = (struct map_lookup *)em->bdev;
		if (map->type & (BTRFS_BLOCK_GROUP_DUP \| BTRFS_BLOCK_GROUP_RAID1))
		ret = map->num_stripes;

Admin message