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

[Alexander Block <ablock84@googlemail.com>]

On Wed, Jul 4, 2012 at 8:27 PM, Alex Lyakas
<alex.bolshoy.btrfs@gmail.com> wrote:
> 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.
>
Hmm you're right, it should be right_start_ctransid. However...the
code was working by accident because the next if does check for left
and right :)
Fixed that in my git repo.
>> +
>> +                       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.