On 7/24/2018 4:55 PM, Christoph Hellwig wrote:
+/*
+ * The virtual start sector is the one that was originally submitted
+ * by the block layer. Due to partitioning, MD/DM cloning, etc. the
+ * actual physical start sector is likely to be different. Remap
+ * protection information to match the physical LBA.
+ *
+ * From SCSI protocol perspective there's a slight difference between
+ * Type 1 and 2. The latter uses command's 32-byte exclusively, and the
+ * reference tag is seeded in the command. This gives us the potential to
+ * avoid virt->phys remapping during write. However, at read time we
+ * don't know whether the virt sector is the same as when we wrote it
+ * (we could be reading from real disk as opposed to MD/DM device. So
+ * we always remap Type 2 making it identical to Type 1.
+ *
+ * Type 3 does not have a reference tag so no remapping is required.
+ */
Please convert the comments for t10_pi_prepare/t10_pi_complete to
kerneldoc format, and remove the mention of 32-byte CDBs, which
are SCSI specific.
something like this:
/**
* t10_pi_prepare() - prepate PI prior submitting request to device
* @rq: request with PI that should be prepared
* @protection_type: PI type (Type 1/Type 2/Type 3)
*
* Description:
* For Type 1/Type 2, the virtual start sector is the one that was
* originally submitted by the block layer for the ref_tag usage. Due to
* partitioning, MD/DM cloning, etc. the actual physical start sector is
* likely to be different. Remap protection information to match the
* physical LBA.
*
* Type 3 does not have a reference tag so no remapping is required.
*/
Otherwise this looks good to me.
Note that after this patch only sd_dif_config_host is left in sd_dif.c,
at which point it might be worth merging into sd.c as a separate patch.
