Btrfs: add transaction space reservation tracepoints

There are a few places where we add to trans->bytes_reserved but don't have the
corresponding trace point.  With these added my tool no longer sees transaction
leaks.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/transaction.c

@@ -637,6 +637,8 @@ struct btrfs_trans_handle *btrfs_start_transaction_fallback_global_rsv(
 
 	trans->block_rsv = &root->fs_info->trans_block_rsv;
 	trans->bytes_reserved = num_bytes;
+	trace_btrfs_space_reservation(root->fs_info, "transaction",
+				      trans->transid, num_bytes, 1);
 
 	return trans;
 }
@@ -1375,7 +1377,9 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 	rsv = trans->block_rsv;
 	trans->block_rsv = &pending->block_rsv;
 	trans->bytes_reserved = trans->block_rsv->reserved;
-
+	trace_btrfs_space_reservation(root->fs_info, "transaction",
+				      trans->transid,
+				      trans->bytes_reserved, 1);
 	dentry = pending->dentry;
 	parent_inode = pending->dir;
 	parent_root = BTRFS_I(parent_inode)->root;