Re: [RFC PATCH 5/7] Btrfs: add btrfs_compare_trees function

Hi Alex,

+                       spin_lock(&left_root->root_times_lock);
+                       ctransid = btrfs_root_ctransid(&left_root->root_item);
+                       spin_unlock(&left_root->root_times_lock);
+                       if (ctransid != left_start_ctransid)
+                               left_start_ctransid = 0;
+
+                       spin_lock(&right_root->root_times_lock);
+                       ctransid = btrfs_root_ctransid(&right_root->root_item);
+                       spin_unlock(&right_root->root_times_lock);
+                       if (ctransid != right_start_ctransid)
+                               left_start_ctransid = 0;

Shouldn't it be here right_start_ctransid=0? Otherwise,
right_start_ctransid is pretty useless in this function.

+
+                       if (!left_start_ctransid || !right_start_ctransid) {
+                               WARN(1, KERN_WARNING
+                                       "btrfs: btrfs_compare_tree detected "
+                                       "a change in one of the trees while "
+                                       "iterating. This is probably a "
+                                       "bug.\n");
+                               ret = -EIO;
+                               goto out;
+                       }

I am reading the code have more questions (and comments), but will
send them all later.

Alex.