Btrfs: stop refusing the relocation of chunk 0

AFAICT chunk 0 is no longer special, and so it should be restriped just
like every other chunk.  One reason for this change is us refusing the
relocation can lead to filesystems that can only be mounted ro, and
never rw -- see the bugzilla [1] for details.  The other reason is that
device removal code is already doing this: it will happily relocate
chunk 0 is part of shrinking the device.

[1] https://bugzilla.kernel.org/show_bug.cgi?id=60594

Reported-by: Xavier Bassery <xavier@bartica.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index f42e412901249f1a01b94af9a7f0f3d17a57556c..603cce85764f2587ef07a468989256b229ce160c 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2997,10 +2997,6 @@ again:
                if (found_key.objectid != key.objectid)
                        break;
 
-               /* chunk zero is special */
-               if (found_key.offset == 0)
-                       break;
-
                chunk = btrfs_item_ptr(leaf, slot, struct btrfs_chunk);
 
                if (!counting) {
@@ -3036,6 +3032,8 @@ again:
                        spin_unlock(&fs_info->balance_lock);
                }
 loop:
+               if (found_key.offset == 0)
+                       break;
                key.offset = found_key.offset - 1;
        }