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Commit a7a16fd7 authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: Fix deadlock while searching for dead roots on mount 



btrfs_find_dead_roots called btrfs_read_fs_root_no_radix, which
means we end up calling btrfs_search_slot with a path already held.

The fix is to remember the key inside btrfs_find_dead_roots and drop
the path.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent f9efa9c7

fs/btrfs/root-tree.c

+9 −1
Original line number Original line Diff line number Diff line
@@ -154,6 +154,7 @@ int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid, 
	struct btrfs_item *item;

	struct btrfs_item *item;

	struct btrfs_root_item *ri;

	struct btrfs_root_item *ri;

	struct btrfs_key key;

	struct btrfs_key key;

	struct btrfs_key found_key;

	struct btrfs_path *path;

	struct btrfs_path *path;

	int ret;

	int ret;

	u32 nritems;

	u32 nritems;
@@ -166,6 +167,8 @@ int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid, 
	path = btrfs_alloc_path();

	path = btrfs_alloc_path();

	if (!path)

	if (!path)

		return -ENOMEM;

		return -ENOMEM;



again:

	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);

	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);

	if (ret < 0)

	if (ret < 0)

		goto err;

		goto err;
@@ -196,7 +199,11 @@ int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid, 
		if (btrfs_disk_root_refs(leaf, ri) != 0)

		if (btrfs_disk_root_refs(leaf, ri) != 0)

			goto next;

			goto next;





		dead_root = btrfs_read_fs_root_no_radix(root->fs_info, &key);

		memcpy(&found_key, &key, sizeof(key));

		key.offset++;

		btrfs_release_path(root, path);

		dead_root = btrfs_read_fs_root_no_radix(root->fs_info,

							&found_key);

		if (IS_ERR(dead_root)) {

		if (IS_ERR(dead_root)) {

			ret = PTR_ERR(dead_root);

			ret = PTR_ERR(dead_root);

			goto err;

			goto err;
@@ -206,6 +213,7 @@ int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid, 
					  &root->fs_info->dead_roots);

					  &root->fs_info->dead_roots);

		if (ret)

		if (ret)

			goto err;

			goto err;

		goto again;

next:

next:

		slot++;

		slot++;

		path->slots[0]++;

		path->slots[0]++;