Avoid ARC buffer transfrom operations in prefetch

This change will prevent prefetch to perform unnecessary transform
operations on ARC buffer.

Signed-off-by: Jaydeep Kshirsagar <[email protected]>

Author: JkshirsagarMaxlinear

module/zfs/arc.c

@@ -6031,6 +6031,7 @@ arc_read(zio_t *pio, spa_t *spa, const blkptr_t *bp,
 		acb->acb_compressed = compressed_read;
 		acb->acb_encrypted = encrypted_read;
 		acb->acb_noauth = noauth_read;
+		acb->acb_nobuf = no_buf;
 		acb->acb_zb = *zb;
 
 		ASSERT3P(hdr->b_l1hdr.b_acb, ==, NULL);