[PATCH RFC 1/4] btrfs: introduce BTRFS_QGROUP_STATUS_FLAGS_MASK for later expansion

[Qu Wenruo <wqu@suse.com>]

Currently we only have 3 qgroup flags:
- BTRFS_QGROUP_STATUS_FLAG_ON
- BTRFS_QGROUP_STATUS_FLAG_RESCAN
- BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT

These flags matches the on-disk flags used in btrfs_qgroup_status.

But we're going to introduce extra runtime flags which will not reach
disks.

So here we introduce a new mask, BTRFS_QGROUP_STATUS_FLAGS_MASK, to
make sure only those flags can reach disks.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/qgroup.c               | 6 ++++--
 include/uapi/linux/btrfs_tree.h | 4 ++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index db680f5be745..9babf925bd59 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -867,7 +867,8 @@ static int update_qgroup_status_item(struct btrfs_trans_handle *trans)
 	l = path->nodes[0];
 	slot = path->slots[0];
 	ptr = btrfs_item_ptr(l, slot, struct btrfs_qgroup_status_item);
-	btrfs_set_qgroup_status_flags(l, ptr, fs_info->qgroup_flags);
+	btrfs_set_qgroup_status_flags(l, ptr, fs_info->qgroup_flags &
+				      BTRFS_QGROUP_STATUS_FLAGS_MASK);
 	btrfs_set_qgroup_status_generation(l, ptr, trans->transid);
 	btrfs_set_qgroup_status_rescan(l, ptr,
 				fs_info->qgroup_rescan_progress.objectid);
@@ -1027,7 +1028,8 @@ int btrfs_quota_enable(struct btrfs_fs_info *fs_info)
 	btrfs_set_qgroup_status_version(leaf, ptr, BTRFS_QGROUP_STATUS_VERSION);
 	fs_info->qgroup_flags = BTRFS_QGROUP_STATUS_FLAG_ON |
 				BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
-	btrfs_set_qgroup_status_flags(leaf, ptr, fs_info->qgroup_flags);
+	btrfs_set_qgroup_status_flags(leaf, ptr, fs_info->qgroup_flags &
+				      BTRFS_QGROUP_STATUS_FLAGS_MASK);
 	btrfs_set_qgroup_status_rescan(leaf, ptr, 0);
 
 	btrfs_mark_buffer_dirty(leaf);
diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index e1c4c732aaba..86dbd13a88f3 100644
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -973,6 +973,10 @@ static inline __u16 btrfs_qgroup_level(__u64 qgroupid)
  */
 #define BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT	(1ULL << 2)
 
+#define BTRFS_QGROUP_STATUS_FLAGS_MASK	(BTRFS_QGROUP_STATUS_FLAG_ON |\
+					 BTRFS_QGROUP_STATUS_FLAG_RESCAN |\
+					 BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT)
+
 #define BTRFS_QGROUP_STATUS_VERSION        1
 
 struct btrfs_qgroup_status_item {
-- 
2.32.0