On Sun, 2015-04-05 at 23:59 +0900, Akinobu Mita wrote: > The scatterlist for protection information which is passed to > sbc_dif_verify_read() or sbc_dif_verify_write() requires that > neighboring scatterlist entries are contiguous or chained so that they > can be iterated by sg_next(). > > However, the protection information for RD-MCP backends could be located > in the multiple scatterlist arrays when the ramdisk space is too large. > So if the read/write request straddles this boundary, sbc_dif_verify_read() > or sbc_dif_verify_write() can't iterate all scatterlist entries. > > This fixes it by allocating temporary scatterlist if it is needed. > > 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] > --- > * No change from v1 > > drivers/target/target_core_rd.c | 39 +++++++++++++++++++++++++++++++++++---- > 1 file changed, 35 insertions(+), 4 deletions(-) > > diff --git a/drivers/target/target_core_rd.c b/drivers/target/target_core_rd.c > index ac5e8d2..6e25eaa 100644 > --- a/drivers/target/target_core_rd.c > +++ b/drivers/target/target_core_rd.c > @@ -390,11 +390,12 @@ static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd, > dif_verify dif_verify) > struct se_device *se_dev = cmd->se_dev; > struct rd_dev *dev = RD_DEV(se_dev); > struct rd_dev_sg_table *prot_table; > + bool need_to_release = false; > struct scatterlist *prot_sg; > u32 sectors = cmd->data_length / se_dev->dev_attrib.block_size; > - u32 prot_offset, prot_page; > + u32 prot_offset, prot_page, prot_npages; > u64 tmp; > - sense_reason_t rc; > + sense_reason_t rc = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; > > tmp = cmd->t_task_lba * se_dev->prot_length; > prot_offset = do_div(tmp, PAGE_SIZE); > @@ -404,10 +405,40 @@ static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd, > dif_verify dif_verify) > if (!prot_table) > return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; > > - prot_sg = &prot_table->sg_table[prot_page - > - prot_table->page_start_offset]; > + prot_npages = DIV_ROUND_UP(prot_offset + sectors * se_dev->prot_length, > + PAGE_SIZE); > + > + /* prot pages straddles multiple scatterlist tables */ > + if (prot_table->page_end_offset < prot_page + prot_npages - 1) { > + int i; > + > + prot_sg = kcalloc(prot_npages, sizeof(*prot_sg), GFP_KERNEL); > + if (!prot_sg) > + return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; > + > + need_to_release = true; > + sg_init_table(prot_sg, prot_npages); > + > + for (i = 0; i < prot_npages; i++) { > + if (prot_page + i > prot_table->page_end_offset) { > + prot_table = rd_get_prot_table(dev, > + prot_page + i); > + if (!prot_table) > + goto out; > + sg_unmark_end(&prot_sg[i - 1]); > + } > + prot_sg[i] = prot_table->sg_table[prot_page + i - > + prot_table->page_start_offset]; > + } > + } else { > + prot_sg = &prot_table->sg_table[prot_page - > + prot_table->page_start_offset]; > + } >
Mmm, how about just explicitly doing sg_link() at prot_table scatterlist creation time instead..? That would save the extra allocation above, and AFAICT make for simpler code. --nab -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
