1 files changed, 6 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 9d89c1648e8e..1bcfcdb23cf4 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -2769,9 +2769,13 @@ again:
                  * the commit roots are read only
                  * so we always do read locks
                  */
+                if (p->need_commit_sem)
+                        down_read(&root->fs_info->commit_root_sem);
                 b = root->commit_root;
                 extent_buffer_get(b);
                 level = btrfs_header_level(b);
+                if (p->need_commit_sem)
+                        up_read(&root->fs_info->commit_root_sem);
                 if (!p->skip_locking)
                         btrfs_tree_read_lock(b);
         } else {
@@ -5436,6 +5440,7 @@ int btrfs_compare_trees(struct btrfs_root *left_root,
          *   the right if possible or go up and right.
          */
 
+        down_read(&left_root->fs_info->commit_root_sem);
         left_level = btrfs_header_level(left_root->commit_root);
         left_root_level = left_level;
         left_path->nodes[left_level] = left_root->commit_root;
@@ -5445,6 +5450,7 @@ int btrfs_compare_trees(struct btrfs_root *left_root,
         right_root_level = right_level;
         right_path->nodes[right_level] = right_root->commit_root;
         extent_buffer_get(right_path->nodes[right_level]);
+        up_read(&left_root->fs_info->commit_root_sem);
 
         if (left_level == 0)
                 btrfs_item_key_to_cpu(left_path->nodes[left_level],