btrfs: extent-tree: Detect bytes_pinned underflow earlier

Introduce a new wrapper update_bytes_pinned to replace open coded
bytes_pinned modifiers. Now the underflows of space_info::bytes_pinned
get detected and reported.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent-tree.c

@@ -67,6 +67,7 @@ static inline void update_##name(struct btrfs_space_info *sinfo,	\
 }
 
 DECLARE_SPACE_INFO_UPDATE(bytes_may_use);
+DECLARE_SPACE_INFO_UPDATE(bytes_pinned);
 
 static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
 			       struct btrfs_delayed_ref_node *node, u64 parent,
@@ -6165,7 +6166,7 @@ static int update_block_group(struct btrfs_trans_handle *trans,
 			old_val -= num_bytes;
 			btrfs_set_block_group_used(&cache->item, old_val);
 			cache->pinned += num_bytes;
-			cache->space_info->bytes_pinned += num_bytes;
+			update_bytes_pinned(cache->space_info, num_bytes);
 			cache->space_info->bytes_used -= num_bytes;
 			cache->space_info->disk_used -= num_bytes * factor;
 			spin_unlock(&cache->lock);
@@ -6236,7 +6237,7 @@ static int pin_down_extent(struct btrfs_fs_info *fs_info,
 	spin_lock(&cache->space_info->lock);
 	spin_lock(&cache->lock);
 	cache->pinned += num_bytes;
-	cache->space_info->bytes_pinned += num_bytes;
+	update_bytes_pinned(cache->space_info, num_bytes);
 	if (reserved) {
 		cache->reserved -= num_bytes;
 		cache->space_info->bytes_reserved -= num_bytes;
@@ -6601,7 +6602,7 @@ static int unpin_extent_range(struct btrfs_fs_info *fs_info,
 		spin_lock(&space_info->lock);
 		spin_lock(&cache->lock);
 		cache->pinned -= len;
-		space_info->bytes_pinned -= len;
+		update_bytes_pinned(space_info, -len);
 
 		trace_btrfs_space_reservation(fs_info, "pinned",
 					      space_info->flags, len, 0);
@@ -10712,7 +10713,7 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
 		spin_lock(&space_info->lock);
 		spin_lock(&block_group->lock);
 
-		space_info->bytes_pinned -= block_group->pinned;
+		update_bytes_pinned(space_info, -block_group->pinned);
 		space_info->bytes_readonly += block_group->pinned;
 		percpu_counter_add_batch(&space_info->total_bytes_pinned,
 				   -block_group->pinned,