Messages in this thread | | | Date | Thu, 9 Jan 2014 12:32:26 +0200 | From | Sagi Grimberg <> | Subject | Re: [PATCH 13/14] target/rd: Add DIF protection into rd_execute_rw |
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On 1/8/2014 10:36 PM, Nicholas A. Bellinger wrote: > From: Nicholas Bellinger <nab@linux-iscsi.org> > > 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 <martin.petersen@oracle.com> > Cc: Christoph Hellwig <hch@lst.de> > Cc: Hannes Reinecke <hare@suse.de> > Cc: Sagi Grimberg <sagig@mellanox.com> > Cc: Or Gerlitz <ogerlitz@mellanox.com> > Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> > --- > 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. I assume that if backstore DIF verify is offloaded as well it does not really matter.
Sagi.
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