| Message ID | 1429972410-7146-5-git-send-email-akinobu.mita@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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 <akinobu.mita@gmail.com> > Cc: Nicholas Bellinger <nab@linux-iscsi.org> > Cc: Sagi Grimberg <sagig@mellanox.com> > Cc: "Martin K. Petersen" <martin.petersen@oracle.com> > Cc: Christoph Hellwig <hch@lst.de> > Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> > Cc: target-devel@vger.kernel.org > Cc: linux-scsi@vger.kernel.org > --- > * 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); > -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
2015-04-26 18:53 GMT+09:00 Sagi Grimberg <sagig@dev.mellanox.co.il>: > 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)? Sounds good. I'll take the idea. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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);
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. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Nicholas Bellinger <nab@linux-iscsi.org> Cc: Sagi Grimberg <sagig@mellanox.com> Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Cc: Christoph Hellwig <hch@lst.de> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: target-devel@vger.kernel.org Cc: linux-scsi@vger.kernel.org --- * Changes from v2: - Handle odd SG mapping correctly instead of giving up drivers/target/target_core_sbc.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+)