block: Integrity checksum flag

Make the choice of checksum a per-I/O property by introducing a flag
that can be inspected by the SCSI layer. There are several reasons for
this:

 1. It allows us to switch choice of checksum without unloading and
    reloading the HBA driver.

 2. During error recovery we need to be able to tell the HBA that
    checksums read from disk should not be verified and converted to IP
    checksums.

 3. For error injection purposes we need to be able to write a bad guard
    tag to storage. Since the storage device only supports T10 CRC we
    need to be able to disable IP checksum conversion on the HBA.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/scsi/sd_dif.c b/drivers/scsi/sd_dif.c
index 4ce636fdc15f..2198abee619e 100644
--- a/drivers/scsi/sd_dif.c
+++ b/drivers/scsi/sd_dif.c
@@ -255,12 +255,14 @@ void sd_dif_config_host(struct scsi_disk *sdkp)
                 return;
 
         /* Enable DMA of protection information */
-        if (scsi_host_get_guard(sdkp->device->host) & SHOST_DIX_GUARD_IP)
+        if (scsi_host_get_guard(sdkp->device->host) & SHOST_DIX_GUARD_IP) {
                 if (type == SD_DIF_TYPE3_PROTECTION)
                         blk_integrity_register(disk, &dif_type3_integrity_ip);
                 else
                         blk_integrity_register(disk, &dif_type1_integrity_ip);
-        else
+
+                disk->integrity->flags |= BLK_INTEGRITY_IP_CHECKSUM;
+        } else
                 if (type == SD_DIF_TYPE3_PROTECTION)
                         blk_integrity_register(disk, &dif_type3_integrity_crc);
                 else