scsi: sd: Use cached ATA Information VPD page

Since the ATA Information VPD is now cached at device discovery time it is
no longer necessary to request this page when we configure WRITE SAME.
Instead use the cached information to determine if this disk sits behind a
SCSI-ATA translation layer.

Link: https://lore.kernel.org/r/20220302053559.32147-7-martin.petersen@oracle.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: martinkpetersen

drivers/scsi/sd.c

@@ -2996,17 +2996,19 @@ static void sd_read_write_same(struct scsi_disk *sdkp, unsigned char *buffer)
 	}
 
 	if (scsi_report_opcode(sdev, buffer, SD_BUF_SIZE, INQUIRY) < 0) {
-		/* too large values might cause issues with arcmsr */
-		int vpd_buf_len = 64;
+		struct scsi_vpd *vpd;
 
 		sdev->no_report_opcodes = 1;
 
 		/* Disable WRITE SAME if REPORT SUPPORTED OPERATION
 		 * CODES is unsupported and the device has an ATA
 		 * Information VPD page (SAT).
 		 */
-		if (!scsi_get_vpd_page(sdev, 0x89, buffer, vpd_buf_len))
+		rcu_read_lock();
+		vpd = rcu_dereference(sdev->vpd_pg89);
+		if (vpd)
 			sdev->no_write_same = 1;
+		rcu_read_unlock();
 	}
 
 	if (scsi_report_opcode(sdev, buffer, SD_BUF_SIZE, WRITE_SAME_16) == 1)