Btrfs: create the uuid tree on remount rw

Users have been complaining of the uuid tree stuff warning that there is no uuid
root when trying to do snapshot operations.  This is because if you mount -o ro
we will not create the uuid tree.  But then if you mount -o rw,remount we will
still not create it and then any subsequent snapshot/subvol operations you try
to do will fail gloriously.  Fix this by creating the uuid_root on remount rw if
it was not already there.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 6ab0df59b6c4..e913328d0f2a 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1383,6 +1383,16 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
                         pr_warn("btrfs: failed to resume dev_replace\n");
                         goto restore;
                 }
+
+                if (!fs_info->uuid_root) {
+                        pr_info("btrfs: creating UUID tree\n");
+                        ret = btrfs_create_uuid_tree(fs_info);
+                        if (ret) {
+                                pr_warn("btrfs: failed to create the uuid tree"
+                                        "%d\n", ret);
+                                goto restore;
+                        }
+                }
                 sb->s_flags &= ~MS_RDONLY;
         }
 out: