Btrfs: Properly find the root for snapshotted blocks during chunk relocation

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 45 insertions, 1 deletions

diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 08f19ec..8bf21ba 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -21,6 +21,51 @@
 #include "disk-io.h"
 #include "print-tree.h"
 
+/*
+ * returns 0 on finding something, 1 if no more roots are there
+ * and < 0 on error
+ */
+int btrfs_search_root(struct btrfs_root *root, u64 search_start,
+		      u64 *found_objectid)
+{
+	struct btrfs_path *path;
+	struct btrfs_key search_key;
+	int ret;
+
+	root = root->fs_info->tree_root;
+	search_key.objectid = search_start;
+	search_key.type = (u8)-1;
+	search_key.offset = (u64)-1;
+
+	path = btrfs_alloc_path();
+	BUG_ON(!path);
+again:
+	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
+	if (ret < 0)
+		goto out;
+	if (ret == 0) {
+		ret = 1;
+		goto out;
+	}
+	if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
+		ret = btrfs_next_leaf(root, path);
+		if (ret)
+			goto out;
+	}
+	btrfs_item_key_to_cpu(path->nodes[0], &search_key, path->slots[0]);
+	if (search_key.type != BTRFS_ROOT_ITEM_KEY) {
+		search_key.offset++;
+		btrfs_release_path(root, path);
+		goto again;
+	}
+	ret = 0;
+	*found_objectid = search_key.objectid;
+
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
 int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
 			struct btrfs_root_item *item, struct btrfs_key *key)
 {
@@ -55,7 +100,6 @@ int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
 	memcpy(key, &found_key, sizeof(found_key));
 	ret = 0;
 out:
-	btrfs_release_path(root, path);
 	btrfs_free_path(path);
 	return ret;
 }