From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sagi Grimberg Subject: Re: [PATCH v3 4/5] target: Fix sbc_dif_generate() and sbc_dif_verify() for WRITE SAME Date: Sun, 26 Apr 2015 12:53:21 +0300 Message-ID: <553CB591.4040807@dev.mellanox.co.il> References: <1429972410-7146-1-git-send-email-akinobu.mita@gmail.com> <1429972410-7146-5-git-send-email-akinobu.mita@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wi0-f174.google.com ([209.85.212.174]:37891 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751482AbbDZJxo (ORCPT ); Sun, 26 Apr 2015 05:53:44 -0400 Received: by wiun10 with SMTP id n10so60975683wiu.1 for ; Sun, 26 Apr 2015 02:53:43 -0700 (PDT) In-Reply-To: <1429972410-7146-5-git-send-email-akinobu.mita@gmail.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Akinobu Mita , target-devel@vger.kernel.org Cc: Nicholas Bellinger , Sagi Grimberg , "Martin K. Petersen" , Christoph Hellwig , "James E.J. Bottomley" , linux-scsi@vger.kernel.org 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 > Cc: Nicholas Bellinger > Cc: Sagi Grimberg > Cc: "Martin K. Petersen" > Cc: Christoph Hellwig > Cc: "James E.J. Bottomley" > 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); >