On 4/25/2015 5:33 PM, Akinobu Mita wrote:
For WRITE SAME, data transfer memory only contains a single block but
protection information is required for all blocks that are written by
the command.
This makes sbc_dif_generate() and sbc_dif_verify() work for WRITE_SAME.
This feels a bit like an overshoot...
You only have 1 block, is it really a good idea to calculate
the CRC over and over for write same? Wouldn't it be better to
have a really simple sbc_dif_generate_same() that calculates the
block CRC once and uses it for the entire payload (and watches for
Type 1 to increment the ref-tag)?
Signed-off-by: Akinobu Mita <[email protected]>
Cc: Nicholas Bellinger <[email protected]>
Cc: Sagi Grimberg <[email protected]>
Cc: "Martin K. Petersen" <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: "James E.J. Bottomley" <[email protected]>
Cc: [email protected]
Cc: [email protected]
---
* Changes from v2:
- Handle odd SG mapping correctly instead of giving up
drivers/target/target_core_sbc.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c
index 33d2426..10c7cb9 100644
--- a/drivers/target/target_core_sbc.c
+++ b/drivers/target/target_core_sbc.c
@@ -1177,6 +1177,24 @@ err:
}
EXPORT_SYMBOL(sbc_execute_unmap);
+static bool sbc_is_write_same(struct se_cmd *cmd)
+{
+ u16 service_action;
+
+ switch (cmd->t_task_cdb[0]) {
+ case WRITE_SAME:
+ case WRITE_SAME_16:
+ return true;
+ case VARIABLE_LENGTH_CMD:
+ service_action = get_unaligned_be16(&cmd->t_task_cdb[8]);
+ if (service_action == WRITE_SAME_32)
+ return true;
+ break;
+ }
+
+ return false;
+}
+
void
sbc_dif_generate(struct se_cmd *cmd)
{
@@ -1187,6 +1205,7 @@ sbc_dif_generate(struct se_cmd *cmd)
void *daddr, *paddr;
int i, j, offset = 0;
unsigned int block_size = dev->dev_attrib.block_size;
+ bool is_write_same = sbc_is_write_same(cmd);
for_each_sg(cmd->t_prot_sg, psg, cmd->t_prot_nents, i) {
paddr = kmap_atomic(sg_page(psg)) + psg->offset;
@@ -1201,6 +1220,8 @@ sbc_dif_generate(struct se_cmd *cmd)
offset -= dsg->length;
kunmap_atomic(daddr);
dsg = sg_next(dsg);
+ if (!dsg && is_write_same)
+ dsg = cmd->t_data_sg;
daddr = kmap_atomic(sg_page(dsg)) + dsg->offset;
}
@@ -1211,6 +1232,8 @@ sbc_dif_generate(struct se_cmd *cmd)
if (avail < block_size) {
kunmap_atomic(daddr);
dsg = sg_next(dsg);
+ if (!dsg && is_write_same)
+ dsg = cmd->t_data_sg;
daddr = kmap_atomic(sg_page(dsg)) + dsg->offset;
offset = block_size - avail;
crc = crc_t10dif_update(crc, daddr, offset);
@@ -1336,6 +1359,7 @@ sbc_dif_verify(struct se_cmd *cmd, sector_t start,
unsigned int sectors,
sense_reason_t rc;
int dsg_off = 0;
unsigned int block_size = dev->dev_attrib.block_size;
+ bool is_write_same = sbc_is_write_same(cmd);
for (; psg && sector < start + sectors; psg = sg_next(psg)) {
paddr = kmap_atomic(sg_page(psg)) + psg->offset;
@@ -1351,6 +1375,8 @@ sbc_dif_verify(struct se_cmd *cmd, sector_t start,
unsigned int sectors,
dsg_off -= dsg->length;
kunmap_atomic(daddr);
dsg = sg_next(dsg);
+ if (!dsg && is_write_same)
+ dsg = cmd->t_data_sg;
daddr = kmap_atomic(sg_page(dsg)) + dsg->offset;
}
@@ -1372,6 +1398,8 @@ sbc_dif_verify(struct se_cmd *cmd, sector_t start,
unsigned int sectors,
if (avail < block_size) {
kunmap_atomic(daddr);
dsg = sg_next(dsg);
+ if (!dsg && is_write_same)
+ dsg = cmd->t_data_sg;
daddr = kmap_atomic(sg_page(dsg)) + dsg->offset;
dsg_off = block_size - avail;
crc = crc_t10dif_update(crc, daddr, dsg_off);
--
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