+typedef sense_reason_t (*dif_verify)(struct se_cmd *, sector_t, unsigned int,
+ unsigned int, struct scatterlist *, int);
+
+static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd, dif_verify dif_verify)
+{
+ struct se_device *se_dev = cmd->se_dev;
+ struct rd_dev *dev = RD_DEV(se_dev);
+ struct rd_dev_sg_table *prot_table;
+ bool need_to_release = false;
+ struct scatterlist *prot_sg;
+ u32 sectors = cmd->data_length / se_dev->dev_attrib.block_size;
+ u32 prot_offset, prot_page;
+ u32 prot_npages __maybe_unused;
+ u64 tmp;
+ sense_reason_t rc = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+
+ tmp = cmd->t_task_lba * se_dev->prot_length;
+ prot_offset = do_div(tmp, PAGE_SIZE);
+ prot_page = tmp;
+
+ prot_table = rd_get_prot_table(dev, prot_page);
+ if (!prot_table)
+ return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+
+ prot_sg = &prot_table->sg_table[prot_page -
+ prot_table->page_start_offset];
+
+#ifndef CONFIG_ARCH_HAS_SG_CHAIN
+
+ prot_npages = DIV_ROUND_UP(prot_offset + sectors * se_dev->prot_length,
+ PAGE_SIZE);
+
+ /*
+ * Allocate temporaly contiguous scatterlist entries if prot pages
+ * straddles multiple scatterlist tables.
+ */
+ if (prot_table->page_end_offset < prot_page + prot_npages - 1) {
+ int i;
+
+ prot_sg = kcalloc(prot_npages, sizeof(*prot_sg), GFP_KERNEL);
+ if (!prot_sg)
+ return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+
+ need_to_release = true;
+ sg_init_table(prot_sg, prot_npages);
+
+ for (i = 0; i < prot_npages; i++) {
+ if (prot_page + i > prot_table->page_end_offset) {
+ prot_table = rd_get_prot_table(dev,
+ prot_page + i);
+ if (!prot_table) {
+ kfree(prot_sg);
+ return rc;
+ }
+ sg_unmark_end(&prot_sg[i - 1]);
+ }
+ prot_sg[i] = prot_table->sg_table[prot_page + i -
+ prot_table->page_start_offset];
+ }
+ }
+
+#endif /* !CONFIG_ARCH_HAS_SG_CHAIN */
+
+ rc = dif_verify(cmd, cmd->t_task_lba, sectors, 0, prot_sg, prot_offset);
+ if (need_to_release)
+ kfree(prot_sg);
+
+ return rc;
+}
+