Adding changes to avoid unnecessary transform operations in prefetch …

…algorithm

This change is needed as extra transform operations are getting
performed on data read from Disk to L1ARC through prefetch algoirhtm.
These operations are not required when ARC is in compressed state and
data is read with ZIO through prefetch algorithm.

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

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);