xfs: always init bma in xfs_bmapi_write

Always init the tp/ip fields of bma in xfs_bmapi_write so that the
bmapi_finish at the bottom never trips over null transaction or inode
pointers.

Coverity-id: 1443964
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

fs/xfs/libxfs/xfs_bmap.c

@@ -4252,9 +4252,13 @@ xfs_bmapi_write(
 	struct xfs_bmbt_irec	*mval,		/* output: map values */
 	int			*nmap)		/* i/o: mval size/count */
 {
+	struct xfs_bmalloca	bma = {
+		.tp		= tp,
+		.ip		= ip,
+		.total		= total,
+	};
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_ifork	*ifp;
-	struct xfs_bmalloca	bma = { NULL };	/* args for xfs_bmap_alloc */
 	xfs_fileoff_t		end;		/* end of mapped file region */
 	bool			eof = false;	/* after the end of extents */
 	int			error;		/* error return */
@@ -4322,10 +4326,6 @@ xfs_bmapi_write(
 		eof = true;
 	if (!xfs_iext_peek_prev_extent(ifp, &bma.icur, &bma.prev))
 		bma.prev.br_startoff = NULLFILEOFF;
-	bma.tp = tp;
-	bma.ip = ip;
-	bma.total = total;
-	bma.datatype = 0;
 	bma.minleft = xfs_bmapi_minleft(tp, ip, whichfork);
 
 	n = 0;