[PATCH 2/2] btrfs: qgroup: catch reserved space leakage at unmount time

[Qu Wenruo <wqu@xxxxxxxx>]

Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
---
 fs/btrfs/disk-io.c |  6 ++++++
 fs/btrfs/qgroup.c  | 43 +++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/qgroup.h  |  2 +-
 3 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index f8ec2d8606fd..48d047e64461 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -4058,6 +4058,12 @@ void __cold close_ctree(struct btrfs_fs_info *fs_info)
 	ASSERT(list_empty(&fs_info->delayed_iputs));
 	set_bit(BTRFS_FS_CLOSING_DONE, &fs_info->flags);
 
+	if (btrfs_qgroup_has_leak(fs_info)) {
+		WARN(IS_ENABLED(CONFIG_BTRFS_DEBUG),
+		     KERN_ERR "BTRFS: qgroup reserved space leaked\n");
+		btrfs_err(fs_info, "qgroup reserved space leaked\n");
+	}
+
 	btrfs_free_qgroup_config(fs_info);
 	ASSERT(list_empty(&fs_info->delalloc_roots));
 
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 5bd4089ad0e1..3fccf2ffdcf1 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -505,6 +505,49 @@ int btrfs_read_qgroup_config(struct btrfs_fs_info *fs_info)
 	return ret < 0 ? ret : 0;
 }
 
+static u64 btrfs_qgroup_subvolid(u64 qgroupid)
+{
+	return (qgroupid & ((1ULL << BTRFS_QGROUP_LEVEL_SHIFT) - 1));
+}
+/*
+ * Get called for close_ctree() when quota is still enabled.
+ * This verifies we don't leak some reserved space.
+ *
+ * Return false if no reserved space is left.
+ * Return true if some reserved space is leaked.
+ */
+bool btrfs_qgroup_has_leak(struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_qgroup *qgroup;
+	struct rb_node *node;
+	bool ret = false;
+
+	if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))
+		return ret;
+	/*
+	 * Since we're unmounting, there is no race and no need to grab
+	 * qgroup lock.
+	 * And here we don't go post order to provide a more user friendly
+	 * sorted result.
+	 */
+	for (node = rb_first(&fs_info->qgroup_tree); node; node = rb_next(node)) {
+		int i;
+
+		qgroup = rb_entry(node, struct btrfs_qgroup, node);
+		for (i = 0; i < BTRFS_QGROUP_RSV_LAST; i++) {
+			if (qgroup->rsv.values[i]) {
+				ret = true;
+				btrfs_warn(fs_info,
+		"qgroup %llu/%llu has unreleased space, type=%d rsv=%llu",
+				   btrfs_qgroup_level(qgroup->qgroupid),
+				   btrfs_qgroup_subvolid(qgroup->qgroupid),
+				   i, qgroup->rsv.values[i]);
+			}
+		}
+	}
+	return ret;
+}
+
 /*
  * This is called from close_ctree() or open_ctree() or btrfs_quota_disable(),
  * first two are in single-threaded paths.And for the third one, we have set
diff --git a/fs/btrfs/qgroup.h b/fs/btrfs/qgroup.h
index 1bc654459469..e3e9f9df8320 100644
--- a/fs/btrfs/qgroup.h
+++ b/fs/btrfs/qgroup.h
@@ -415,5 +415,5 @@ int btrfs_qgroup_add_swapped_blocks(struct btrfs_trans_handle *trans,
 int btrfs_qgroup_trace_subtree_after_cow(struct btrfs_trans_handle *trans,
 		struct btrfs_root *root, struct extent_buffer *eb);
 void btrfs_qgroup_destroy_extent_records(struct btrfs_transaction *trans);
-
+bool btrfs_qgroup_has_leak(struct btrfs_fs_info *fs_info);
 #endif
-- 
2.26.2