The scatterlist for protection information which is passed to
sbc_dif_verify_read() or sbc_dif_verify_write() requires that
neighboring scatterlist entries are contiguous or chained so that they
can be iterated by sg_next().
However, the protection information for RD-MCP backends could be located
in the multiple scatterlist arrays when the ramdisk space is too large.
So if the read/write request straddles this boundary, sbc_dif_verify_read()
or sbc_dif_verify_write() can't iterate all scatterlist entries.
This problem can be fixed by chaining protection information scatterlist
at creation time. For the architectures which don't support sg chaining
(i.e. !CONFIG_ARCH_HAS_SG_CHAIN), fix it by allocating temporary
scatterlist if needed.
Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
Cc: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Cc: Sagi Grimberg <sagig@xxxxxxxxxxxxxxxxxx>
Cc: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: "James E.J. Bottomley" <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Cc: target-devel@xxxxxxxxxxxxxxx
Cc: linux-scsi@xxxxxxxxxxxxxxx
---
* v3
- Fix it by chaining protection information scatterlist at creation time
if CONFIG_ARCH_HAS_SG_CHAIN is defined.
drivers/target/target_core_rd.c | 67 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 64 insertions(+), 3 deletions(-)
diff --git a/drivers/target/target_core_rd.c b/drivers/target/target_core_rd.c
index ac5e8d2..b4e6de0 100644
--- a/drivers/target/target_core_rd.c
+++ b/drivers/target/target_core_rd.c
@@ -139,10 +139,22 @@ static int rd_allocate_sgl_table(struct rd_dev *rd_dev, struct rd_dev_sg_table *
unsigned char *p;
while (total_sg_needed) {
+ unsigned int chain_entry = 0;
+
sg_per_table = (total_sg_needed > max_sg_per_table) ?
max_sg_per_table : total_sg_needed;
- sg = kzalloc(sg_per_table * sizeof(struct scatterlist),
+#ifdef CONFIG_ARCH_HAS_SG_CHAIN
+
+ /*
+ * Reserve extra element for chain entry
+ */
+ if (sg_per_table < total_sg_needed)
+ chain_entry = 1;
+
+#endif /* CONFIG_ARCH_HAS_SG_CHAIN */
+
+ sg = kcalloc(sg_per_table + chain_entry, sizeof(*sg),
GFP_KERNEL);
if (!sg) {
pr_err("Unable to allocate scatterlist array"
@@ -150,7 +162,16 @@ static int rd_allocate_sgl_table(struct rd_dev *rd_dev, struct rd_dev_sg_table *
return -ENOMEM;
}
- sg_init_table(sg, sg_per_table);
+ sg_init_table(sg, sg_per_table + chain_entry);
+
+#ifdef CONFIG_ARCH_HAS_SG_CHAIN
+
+ if (i > 0) {
+ sg_chain(sg_table[i - 1].sg_table,
+ max_sg_per_table + 1, sg);
+ }
+
+#endif /* CONFIG_ARCH_HAS_SG_CHAIN */
sg_table[i].sg_table = sg;
sg_table[i].rd_sg_count = sg_per_table;
@@ -390,11 +411,13 @@ 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;
+ 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);
@@ -407,7 +430,45 @@ static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd, dif_verify dif_verify)
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;
}
--
1.9.1
--
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