target/sbc: Add sbc_dif_generate software emulation

This patch adds WRITE_INSERT emulation within target-core using TYPE1 / TYPE3 PI modes in sbc_dif_generate() code. This is useful in order for existing legacy fabrics that do not support protection offloads to interact with backend devices that currently have T10 PI enabled. v2 changes: - Rename to sbc_dif_generate() (Sagi) Cc: Martin K. Petersen <[email protected]> Cc: Sagi Grimberg <[email protected]> Cc: Or Gerlitz <[email protected]> Cc: Quinn Tran <[email protected]> Cc: Giridhar Malavali <[email protected]> Signed-off-by: Nicholas Bellinger <[email protected]>
mrcsosa · Apr 7, 2014 · 66a3d5b · 66a3d5b
1 parent 2d33598
commit 66a3d5b
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diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c
@@ -1096,6 +1096,50 @@ sbc_execute_unmap(struct se_cmd *cmd,
 }
 EXPORT_SYMBOL(sbc_execute_unmap);
 
+void
+sbc_dif_generate(struct se_cmd *cmd)
+{
+	struct se_device *dev = cmd->se_dev;
+	struct se_dif_v1_tuple *sdt;
+	struct scatterlist *dsg, *psg = cmd->t_prot_sg;
+	sector_t sector = cmd->t_task_lba;
+	void *daddr, *paddr;
+	int i, j, offset = 0;
+
+	for_each_sg(cmd->t_data_sg, dsg, cmd->t_data_nents, i) {
+		daddr = kmap_atomic(sg_page(dsg)) + dsg->offset;
+		paddr = kmap_atomic(sg_page(psg)) + psg->offset;
+
+		for (j = 0; j < dsg->length; j += dev->dev_attrib.block_size) {
+
+			if (offset >= psg->length) {
+				kunmap_atomic(paddr);
+				psg = sg_next(psg);
+				paddr = kmap_atomic(sg_page(psg)) + psg->offset;
+				offset = 0;
+			}
+
+			sdt = paddr + offset;
+			sdt->guard_tag = cpu_to_be16(crc_t10dif(daddr + j,
+						dev->dev_attrib.block_size));
+			if (dev->dev_attrib.pi_prot_type == TARGET_DIF_TYPE1_PROT)
+				sdt->ref_tag = cpu_to_be32(sector & 0xffffffff);
+			sdt->app_tag = 0;
+
+			pr_debug("DIF WRITE INSERT sector: %llu guard_tag: 0x%04x"
+				 " app_tag: 0x%04x ref_tag: %u\n",
+				 (unsigned long long)sector, sdt->guard_tag,
+				 sdt->app_tag, be32_to_cpu(sdt->ref_tag));
+
+			sector++;
+			offset += sizeof(struct se_dif_v1_tuple);
+		}
+
+		kunmap_atomic(paddr);
+		kunmap_atomic(daddr);
+	}
+}
+
 static sense_reason_t
 sbc_dif_v1_verify(struct se_device *dev, struct se_dif_v1_tuple *sdt,
 		  const void *p, sector_t sector, unsigned int ei_lba)

diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
@@ -73,6 +73,7 @@ sense_reason_t sbc_execute_unmap(struct se_cmd *cmd,
 	sense_reason_t (*do_unmap_fn)(struct se_cmd *cmd, void *priv,
 				      sector_t lba, sector_t nolb),
 	void *priv);
+void	sbc_dif_generate(struct se_cmd *);
 sense_reason_t	sbc_dif_verify_write(struct se_cmd *, sector_t, unsigned int,
 				     unsigned int, struct scatterlist *, int);
 sense_reason_t	sbc_dif_verify_read(struct se_cmd *, sector_t, unsigned int,