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>

2 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/bio.h b/include/linux/bio.h
index b508cf69206d..14bff3fe56d4 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -328,6 +328,7 @@ enum bip_flags {
         BIP_MAPPED_INTEGRITY    = 1 << 1, /* ref tag has been remapped */
         BIP_CTRL_NOCHECK        = 1 << 2, /* disable HBA integrity checking */
         BIP_DISK_NOCHECK        = 1 << 3, /* disable disk integrity checking */
+        BIP_IP_CHECKSUM         = 1 << 4, /* IP checksum */
 };
 
 static inline sector_t bip_get_seed(struct bio_integrity_payload *bip)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 4600fc63e3fc..773df190a4ee 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1462,6 +1462,7 @@ enum blk_integrity_flags {
         BLK_INTEGRITY_VERIFY            = 1 << 0,
         BLK_INTEGRITY_GENERATE          = 1 << 1,
         BLK_INTEGRITY_DEVICE_CAPABLE    = 1 << 2,
+        BLK_INTEGRITY_IP_CHECKSUM       = 1 << 3,
 };
 
 struct blk_integrity_iter {