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 08f19ec88092..8bf21ba0a43b 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;
 }