From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sagi Grimberg Subject: Re: [PATCH 2/2] target/rd: Don't pass imcomplete scatterlist entries to sbc_dif_verify_* Date: Sun, 05 Apr 2015 13:10:47 +0300 Message-ID: <55210A27.5020001@dev.mellanox.co.il> References: <1428150268-30260-1-git-send-email-akinobu.mita@gmail.com> <1428150268-30260-2-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-wg0-f54.google.com ([74.125.82.54]:35960 "EHLO mail-wg0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751336AbbDEKKv (ORCPT ); Sun, 5 Apr 2015 06:10:51 -0400 Received: by wgra20 with SMTP id a20so6946411wgr.3 for ; Sun, 05 Apr 2015 03:10:49 -0700 (PDT) In-Reply-To: <1428150268-30260-2-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 , Asias He , "Martin K. Petersen" , Christoph Hellwig , "James E.J. Bottomley" , linux-scsi@vger.kernel.org On 4/4/2015 3:24 PM, 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 > Cc: Nicholas Bellinger > Cc: Asias He > Cc: "Martin K. Petersen" > Cc: Christoph Hellwig > Cc: "James E.J. Bottomley" > Cc: target-devel@vger.kernel.org > Cc: linux-scsi@vger.kernel.org > --- > 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 4d614c9..19c893d 100644 > --- a/drivers/target/target_core_rd.c > +++ b/drivers/target/target_core_rd.c > @@ -387,11 +387,12 @@ static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd, bool is_write) > 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; > sense_reason_t (*dif_verify)(struct se_cmd *, sector_t, unsigned int, > unsigned int, struct scatterlist *, int) = > is_write ? sbc_dif_verify_write : sbc_dif_verify_read; > @@ -404,10 +405,40 @@ static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd, bool is_write) > 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]; > + } > > rc = dif_verify(cmd, cmd->t_task_lba, sectors, 0, prot_sg, prot_offset); > +out: > + if (need_to_release) > + kfree(prot_sg); I think it is safe to free prot_sg if you just make sure to initialize it to NULL at declaration time, no need for 'need_to_release'.