xfs: slightly tweak an assert in xfs_fs_map_blocks

We should never see delalloc blocks for a pNFS layout, write or not.
Adjust the assert to check for that.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/xfs_pnfs.c

@@ -148,11 +148,11 @@ xfs_fs_map_blocks(
 	if (error)
 		goto out_unlock;
 
+	ASSERT(!nimaps || imap.br_startblock != DELAYSTARTBLOCK);
+
 	if (write) {
 		enum xfs_prealloc_flags	flags = 0;
 
-		ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
-
 		if (!nimaps || imap.br_startblock == HOLESTARTBLOCK) {
 			/*
 			 * xfs_iomap_write_direct() expects to take ownership of