Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751173AbaAJGvB (ORCPT ); Fri, 10 Jan 2014 01:51:01 -0500 Received: from mail.linux-iscsi.org ([67.23.28.174]:45091 "EHLO linux-iscsi.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750793AbaAJGu7 (ORCPT ); Fri, 10 Jan 2014 01:50:59 -0500 Message-ID: <1389336761.5567.403.camel@haakon3.risingtidesystems.com> Subject: Re: [PATCH 13/14] target/rd: Add DIF protection into rd_execute_rw From: "Nicholas A. Bellinger" To: Sagi Grimberg Cc: "Nicholas A. Bellinger" , target-devel , linux-scsi , linux-kernel , "Martin K. Petersen" , Christoph Hellwig , Hannes Reinecke , Or Gerlitz Date: Thu, 09 Jan 2014 22:52:41 -0800 In-Reply-To: <52CE7ABA.9080403@mellanox.com> References: <1389212157-14540-1-git-send-email-nab@daterainc.com> <1389212157-14540-14-git-send-email-nab@daterainc.com> <52CE7ABA.9080403@mellanox.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.4.4-1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2014-01-09 at 12:32 +0200, Sagi Grimberg wrote: > On 1/8/2014 10:36 PM, Nicholas A. Bellinger wrote: > > From: Nicholas Bellinger > > > > This patch adds support for DIF protection into rd_execute_rw() code > > for WRITE/READ I/O using sbc_dif_verify_[write,read]() logic. > > > > It also adds rd_get_prot_table() for locating protection SGLs > > assoicated with the ramdisk backend device. > > > > Cc: Martin K. Petersen > > Cc: Christoph Hellwig > > Cc: Hannes Reinecke > > Cc: Sagi Grimberg > > Cc: Or Gerlitz > > Signed-off-by: Nicholas Bellinger > > --- > > drivers/target/target_core_rd.c | 67 +++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 67 insertions(+) > > > > diff --git a/drivers/target/target_core_rd.c b/drivers/target/target_core_rd.c > > index dd99844..3fd51eb 100644 > > --- a/drivers/target/target_core_rd.c > > +++ b/drivers/target/target_core_rd.c > > @@ -363,6 +363,26 @@ static struct rd_dev_sg_table *rd_get_sg_table(struct rd_dev *rd_dev, u32 page) > > return NULL; > > } > > > > +static struct rd_dev_sg_table *rd_get_prot_table(struct rd_dev *rd_dev, u32 page) > > +{ > > + struct rd_dev_sg_table *sg_table; > > + u32 i, sg_per_table = (RD_MAX_ALLOCATION_SIZE / > > + sizeof(struct scatterlist)); > > + > > + i = page / sg_per_table; > > + if (i < rd_dev->sg_prot_count) { > > + sg_table = &rd_dev->sg_prot_array[i]; > > + if ((sg_table->page_start_offset <= page) && > > + (sg_table->page_end_offset >= page)) > > + return sg_table; > > + } > > + > > + pr_err("Unable to locate struct prot rd_dev_sg_table for page: %u\n", > > + page); > > + > > + return NULL; > > +} > > + > > static sense_reason_t > > rd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, > > enum dma_data_direction data_direction) > > @@ -377,6 +397,7 @@ rd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, > > u32 rd_page; > > u32 src_len; > > u64 tmp; > > + sense_reason_t rc; > > > > if (dev->rd_flags & RDF_NULLIO) { > > target_complete_cmd(cmd, SAM_STAT_GOOD); > > @@ -399,6 +420,29 @@ rd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, > > data_direction == DMA_FROM_DEVICE ? "Read" : "Write", > > cmd->t_task_lba, rd_size, rd_page, rd_offset); > > > > + if ((cmd->se_cmd_flags & SCF_PROT) && se_dev->dev_attrib.pi_prot_type && > > + data_direction == DMA_TO_DEVICE) { > > + sector_t sector = cmd->data_length / se_dev->dev_attrib.block_size; > > + struct rd_dev_sg_table *prot_table; > > + struct scatterlist *prot_sg; > > + u32 prot_offset, prot_page; > > + > > + 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]; > > + > > + rc = sbc_dif_verify_write(cmd, cmd->t_task_lba, sector, 0, > > + prot_sg, prot_offset); > > + if (rc) > > + return rc; > > + } > > + > > src_len = PAGE_SIZE - rd_offset; > > sg_miter_start(&m, sgl, sgl_nents, > > data_direction == DMA_FROM_DEVICE ? > > @@ -460,6 +504,29 @@ rd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, > > } > > sg_miter_stop(&m); > > > > + if ((cmd->se_cmd_flags & SCF_PROT) && se_dev->dev_attrib.pi_prot_type && > > + data_direction == DMA_FROM_DEVICE) { > > + sector_t sector = cmd->data_length / se_dev->dev_attrib.block_size; > > + struct rd_dev_sg_table *prot_table; > > + struct scatterlist *prot_sg; > > + u32 prot_offset, prot_page; > > + > > + 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]; > > + > > + rc = sbc_dif_verify_read(cmd, cmd->t_task_lba, sector, 0, > > + prot_sg, prot_offset); > > + if (rc) > > + return rc; > > + } > > + > > target_complete_cmd(cmd, SAM_STAT_GOOD); > > return 0; > > } > > I wander how we can skip sbc_dif_verify_xxxx if the transport already > offloaded DIF verify. > I think that the transport should signal the core layer that it is able > to offload DIF (ADD/STRIP/PASS/VERIFY), in which case the core should > turn off the backstore DIF verify emulation to sustain performance. So IBLOCK + PSCSI backends will need to be a non interleaved protection PASS for fast path operation, and backend protection emulation is reserved for RAMDISK and perhaps a special FILEIO full emulation mode. > I assume that if backstore DIF verify is offloaded as well it does not > really matter. That is my assumption of well.. --nab -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/