[PATCH] Btrfs: create the uuid tree on remount rw

[Josef Bacik <jbacik@fusionio.com>]

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>
---
 fs/btrfs/super.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 6ab0df5..05cfd79 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 "
+					"%d\n", ret);
+				goto restore;
+			}
+		}
 		sb->s_flags &= ~MS_RDONLY;
 	}
 out:
-- 
1.8.3.1