From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Disseldorp Date: Fri, 30 Oct 2020 21:39:30 +0000 Subject: [PATCH v3 3/4] scsi: target: split out COMPARE AND WRITE memcmp into helper Message-Id: <20201030213931.10720-4-ddiss@suse.de> List-Id: References: <20201030213931.10720-1-ddiss@suse.de> In-Reply-To: <20201030213931.10720-1-ddiss@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: target-devel@vger.kernel.org Cc: linux-scsi@vger.kernel.org, David Disseldorp , Mike Christie In preparation for finding and returning the miscompare offset. Signed-off-by: David Disseldorp Reviewed-by: Mike Christie --- drivers/target/target_core_sbc.c | 121 +++++++++++++++++-------------- 1 file changed, 68 insertions(+), 53 deletions(-) diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c index 5f77dd95f1b9..22d0cbba6ff3 100644 --- a/drivers/target/target_core_sbc.c +++ b/drivers/target/target_core_sbc.c @@ -434,20 +434,75 @@ static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success, return ret; } +/* + * compare @cmp_len bytes of @read_sgl with @cmp_sgl. On miscompare return + * TCM_MISCOMPARE_VERIFY. + */ +static sense_reason_t +compare_and_write_do_cmp(struct scatterlist *read_sgl, unsigned int read_nents, + struct scatterlist *cmp_sgl, unsigned int cmp_nents, + unsigned int cmp_len) +{ + unsigned char *buf = NULL; + struct scatterlist *sg; + sense_reason_t ret; + unsigned int offset; + size_t rc; + int i; + + buf = kzalloc(cmp_len, GFP_KERNEL); + if (!buf) { + ret = TCM_OUT_OF_RESOURCES; + goto out; + } + + rc = sg_copy_to_buffer(cmp_sgl, cmp_nents, buf, cmp_len); + if (!rc) { + pr_err("sg_copy_to_buffer() failed for compare_and_write\n"); + ret = TCM_OUT_OF_RESOURCES; + goto out; + } + /* + * Compare SCSI READ payload against verify payload + */ + offset = 0; + for_each_sg(read_sgl, sg, read_nents, i) { + unsigned int len = min(sg->length, cmp_len); + unsigned char *addr = kmap_atomic(sg_page(sg)); + + if (memcmp(addr, buf + offset, len)) { + pr_warn("Detected MISCOMPARE for addr: %p buf: %p\n", + addr, buf + offset); + kunmap_atomic(addr); + ret = TCM_MISCOMPARE_VERIFY; + goto out; + } + kunmap_atomic(addr); + + offset += len; + cmp_len -= len; + if (!cmp_len) + break; + } + pr_debug("COMPARE AND WRITE read data matches compare data\n"); + ret = TCM_NO_SENSE; +out: + kfree(buf); + return ret; +} + static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool success, int *post_ret) { struct se_device *dev = cmd->se_dev; struct sg_table write_tbl = { }; - struct scatterlist *write_sg, *sg; - unsigned char *buf = NULL, *addr; + struct scatterlist *write_sg; struct sg_mapping_iter m; - unsigned int offset = 0, len; - unsigned int nlbas = cmd->t_task_nolb; + unsigned int len; unsigned int block_size = dev->dev_attrib.block_size; - unsigned int compare_len = (nlbas * block_size); + unsigned int compare_len = (cmd->t_task_nolb * block_size); sense_reason_t ret = TCM_NO_SENSE; - int rc, i; + int i; /* * Handle early failure in transport_generic_request_failure(), @@ -473,12 +528,13 @@ static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool succes goto out; } - buf = kzalloc(cmd->data_length, GFP_KERNEL); - if (!buf) { - pr_err("Unable to allocate compare_and_write buf\n"); - ret = TCM_OUT_OF_RESOURCES; + ret = compare_and_write_do_cmp(cmd->t_bidi_data_sg, + cmd->t_bidi_data_nents, + cmd->t_data_sg, + cmd->t_data_nents, + compare_len); + if (ret) goto out; - } if (sg_alloc_table(&write_tbl, cmd->t_data_nents, GFP_KERNEL) < 0) { pr_err("Unable to allocate compare_and_write sg\n"); @@ -486,44 +542,9 @@ static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool succes goto out; } write_sg = write_tbl.sgl; - /* - * Setup verify and write data payloads from total NumberLBAs. - */ - rc = sg_copy_to_buffer(cmd->t_data_sg, cmd->t_data_nents, buf, - cmd->data_length); - if (!rc) { - pr_err("sg_copy_to_buffer() failed for compare_and_write\n"); - ret = TCM_OUT_OF_RESOURCES; - goto out; - } - /* - * Compare against SCSI READ payload against verify payload - */ - for_each_sg(cmd->t_bidi_data_sg, sg, cmd->t_bidi_data_nents, i) { - addr = (unsigned char *)kmap_atomic(sg_page(sg)); - if (!addr) { - ret = TCM_OUT_OF_RESOURCES; - goto out; - } - - len = min(sg->length, compare_len); - - if (memcmp(addr, buf + offset, len)) { - pr_warn("Detected MISCOMPARE for addr: %p buf: %p\n", - addr, buf + offset); - kunmap_atomic(addr); - goto miscompare; - } - kunmap_atomic(addr); - - offset += len; - compare_len -= len; - if (!compare_len) - break; - } i = 0; - len = cmd->t_task_nolb * block_size; + len = compare_len; sg_miter_start(&m, cmd->t_data_sg, cmd->t_data_nents, SG_MITER_TO_SG); /* * Currently assumes NoLB=1 and SGLs are PAGE_SIZE.. @@ -568,13 +589,8 @@ static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool succes __target_execute_cmd(cmd, false); - kfree(buf); return ret; -miscompare: - pr_warn("Target/%s: Send MISCOMPARE check condition and sense\n", - dev->transport->name); - ret = TCM_MISCOMPARE_VERIFY; out: /* * In the MISCOMPARE or failure case, unlock ->caw_sem obtained in @@ -582,7 +598,6 @@ static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool succes */ up(&dev->caw_sem); sg_free_table(&write_tbl); - kfree(buf); return ret; } -- 2.26.2