From f62c302e6dfe7bb03b35157e1c1b7cdaeabd54f9 Mon Sep 17 00:00:00 2001 From: Anand Jain Date: Wed, 24 May 2023 20:02:38 +0800 Subject: [PATCH] btrfs: add comment about metadata_uuid in btrfs_fs_devices Add comment about metadata_uuid in btrfs_fs_devices. No functional change. Signed-off-by: Anand Jain Signed-off-by: David Sterba --- fs/btrfs/volumes.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index 236ae696c9841..24f30542ef7c8 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -280,7 +280,19 @@ enum btrfs_read_policy { struct btrfs_fs_devices { u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */ + + /* + * UUID written into the btree blocks: + * + * - If metadata_uuid != fsid then super block must have + * BTRFS_FEATURE_INCOMPAT_METADATA_UUID flag set. + * + * - Following shall be true at all times: + * - metadata_uuid == btrfs_header::fsid + * - metadata_uuid == btrfs_dev_item::fsid + */ u8 metadata_uuid[BTRFS_FSID_SIZE]; + struct list_head fs_list; /*