btrfs: free qgroup pertrans reserve on transaction abort

If we abort a transaction, we never run the code that frees the pertrans
qgroup reservation. This results in warnings on unmount as that
reservation has been leaked. The leak isn't a huge issue since the fs is
read-only, but it's better to clean it up when we know we can/should. Do
it during the cleanup_transaction step of aborting.

CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/disk-io.c

@@ -4799,6 +4799,32 @@ void btrfs_cleanup_dirty_bgs(struct btrfs_transaction *cur_trans,
 	}
 }
 
+static void btrfs_free_all_qgroup_pertrans(struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_root *gang[8];
+	int i;
+	int ret;
+
+	spin_lock(&fs_info->fs_roots_radix_lock);
+	while (1) {
+		ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
+						 (void **)gang, 0,
+						 ARRAY_SIZE(gang),
+						 BTRFS_ROOT_TRANS_TAG);
+		if (ret == 0)
+			break;
+		for (i = 0; i < ret; i++) {
+			struct btrfs_root *root = gang[i];
+
+			btrfs_qgroup_free_meta_all_pertrans(root);
+			radix_tree_tag_clear(&fs_info->fs_roots_radix,
+					(unsigned long)root->root_key.objectid,
+					BTRFS_ROOT_TRANS_TAG);
+		}
+	}
+	spin_unlock(&fs_info->fs_roots_radix_lock);
+}
+
 void btrfs_cleanup_one_transaction(struct btrfs_transaction *cur_trans,
 				   struct btrfs_fs_info *fs_info)
 {
@@ -4827,6 +4853,8 @@ void btrfs_cleanup_one_transaction(struct btrfs_transaction *cur_trans,
 				     EXTENT_DIRTY);
 	btrfs_destroy_pinned_extent(fs_info, &cur_trans->pinned_extents);
 
+	btrfs_free_all_qgroup_pertrans(fs_info);
+
 	cur_trans->state =TRANS_STATE_COMPLETED;
 	wake_up(&cur_trans->commit_wait);
 }

fs/btrfs/qgroup.c

@@ -4337,8 +4337,9 @@ static void qgroup_convert_meta(struct btrfs_fs_info *fs_info, u64 ref_root,
 
 		qgroup_rsv_release(fs_info, qgroup, num_bytes,
 				BTRFS_QGROUP_RSV_META_PREALLOC);
-		qgroup_rsv_add(fs_info, qgroup, num_bytes,
-				BTRFS_QGROUP_RSV_META_PERTRANS);
+		if (!sb_rdonly(fs_info->sb))
+			qgroup_rsv_add(fs_info, qgroup, num_bytes,
+				       BTRFS_QGROUP_RSV_META_PERTRANS);
 
 		list_for_each_entry(glist, &qgroup->groups, next_group)
 			qgroup_iterator_add(&qgroup_list, glist->group);

fs/btrfs/transaction.c

@@ -37,8 +37,6 @@
 
 static struct kmem_cache *btrfs_trans_handle_cachep;
 
-#define BTRFS_ROOT_TRANS_TAG 0
-
 /*
  * Transaction states and transitions
  *

fs/btrfs/transaction.h

@@ -12,6 +12,9 @@
 #include "ctree.h"
 #include "misc.h"
 
+/* Radix-tree tag for roots that are part of the trasaction. */
+#define BTRFS_ROOT_TRANS_TAG			0
+
 enum btrfs_trans_state {
 	TRANS_STATE_RUNNING,
 	TRANS_STATE_COMMIT_PREP,