[PATCH 1/7] btrfs: correctly model root qgroup rsv in convert

[Boris Burkov <boris@bur.io>]

We use add_root_meta_rsv and sub_root_meta_rsv to track prealloc and
pertrans reservations for subvols when quotas are enabled. The convert
function does not properly increment pertrans after decrementing
prealloc, so the count is not accurate.

Note: we check that the fs is not read-only to mirror the logic in
qgroup_convert_meta, which checks that before adding to the pertrans rsv.

Fixes: 8287475a2055 ("btrfs: qgroup: Use root::qgroup_meta_rsv_* to record qgroup meta reserved space")
Signed-off-by: Boris Burkov <boris@bur.io>
---
 fs/btrfs/qgroup.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index a8197e25192c..2cba6451d164 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -4492,6 +4492,8 @@ void btrfs_qgroup_convert_reserved_meta(struct btrfs_root *root, int num_bytes)
 				      BTRFS_QGROUP_RSV_META_PREALLOC);
 	trace_qgroup_meta_convert(root, num_bytes);
 	qgroup_convert_meta(fs_info, root->root_key.objectid, num_bytes);
+	if (!sb_rdonly(fs_info->sb))
+		add_root_meta_rsv(root, num_bytes, BTRFS_QGROUP_RSV_META_PERTRANS);
 }
 
 /*
-- 
2.44.0