Commit aee68ee5 authored by Josef Bacik's avatar Josef Bacik
Browse files

Btrfs: fix not being able to find skinny extents during relocate 



We unconditionally search for the EXTENT_ITEM_KEY for metadata during balance,
and then check the key that we found to see if it is actually a
METADATA_ITEM_KEY, but this doesn't work right because METADATA is a higher key
value, so if what we are looking for happens to be the first item in the leaf
the search will dump us out at the previous leaf, and we won't find our item.
So instead do what we do everywhere else, search for the skinny extent first and
if we don't find it go back and re-search for the extent item.  This patch fixes
the panic I was hitting when balancing a large file system with skinny extents.
Thanks,

Signed-off-by: default avatarJosef Bacik <jbacik@fusionio.com>
parent da61d31a

fs/btrfs/relocation.c

+27 −8
Original line number Diff line number Diff line
@@ -3309,6 +3309,8 @@ static int __add_tree_block(struct reloc_control *rc, 
	struct btrfs_path *path;

	struct btrfs_key key;

	int ret;

	bool skinny = btrfs_fs_incompat(rc->extent_root->fs_info,

					SKINNY_METADATA);



	if (tree_block_processed(bytenr, blocksize, rc))

		return 0;
@@ -3319,10 +3321,15 @@ static int __add_tree_block(struct reloc_control *rc, 
	path = btrfs_alloc_path();

	if (!path)

		return -ENOMEM;



again:

	key.objectid = bytenr;

	if (skinny) {

		key.type = BTRFS_METADATA_ITEM_KEY;

		key.offset = (u64)-1;

	} else {

		key.type = BTRFS_EXTENT_ITEM_KEY;

		key.offset = blocksize;

	}



	path->search_commit_root = 1;

	path->skip_locking = 1;
@@ -3330,12 +3337,24 @@ static int __add_tree_block(struct reloc_control *rc, 
	if (ret < 0)

		goto out;



	btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);

	if (ret > 0) {

	if (ret > 0 && skinny) {

		if (path->slots[0]) {

			path->slots[0]--;

			btrfs_item_key_to_cpu(path->nodes[0], &key,

					      path->slots[0]);

			if (key.objectid == bytenr &&

		    key.type == BTRFS_METADATA_ITEM_KEY)

			    (key.type == BTRFS_METADATA_ITEM_KEY ||

			     (key.type == BTRFS_EXTENT_ITEM_KEY &&

			      key.offset == blocksize)))

				ret = 0;

		}



		if (ret) {

			skinny = false;

			btrfs_release_path(path);

			goto again;

		}

	}

	BUG_ON(ret);



	ret = add_tree_block(rc, &key, path, blocks);

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