btrfs: Don't generate UUID for non-fs tree

btrfs_create_tree() will unconditionally generate UUID for any root.
So for quota tree and data reloc tree created by kernel, they will have
unique UUIDs.

However UUID in root item is only referred by UUID tree, which only
records UUID for fs trees.  This makes unique UUIDs for quota/data reloc
tree meaningless.

Leave the UUID as zero for non-fs tree, making btrfs-debug-tree output
less confusing.

Reported-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index a8ecccfc36ded1d9470deb0d78f77bcdacb6d0cf..ec9aa34bb6ebd63b29f84bfb581fc24132138be1 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1243,7 +1243,7 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
        struct btrfs_root *root;
        struct btrfs_key key;
        int ret = 0;
-       uuid_le uuid;
+       uuid_le uuid = NULL_UUID_LE;
 
        root = btrfs_alloc_root(fs_info, GFP_KERNEL);
        if (!root)
@@ -1284,7 +1284,8 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
        btrfs_set_root_used(&root->root_item, leaf->len);
        btrfs_set_root_last_snapshot(&root->root_item, 0);
        btrfs_set_root_dirid(&root->root_item, 0);
-       uuid_le_gen(&uuid);
+       if (is_fstree(objectid))
+               uuid_le_gen(&uuid);
        memcpy(root->root_item.uuid, uuid.b, BTRFS_UUID_SIZE);
        root->root_item.drop_level = 0;