Commit ab628b9f authored by David Disseldorp's avatar David Disseldorp Committed by Martin K. Petersen
Browse files

scsi: target: Split out COMPARE AND WRITE memcmp into helper 

In preparation for finding and returning the miscompare offset.

Link: https://lore.kernel.org/r/20201031233211.5207-4-ddiss@suse.de


Reviewed-by: default avatarMike Christie <michael.christie@oracle.com>
Signed-off-by: default avatarDavid Disseldorp <ddiss@suse.de>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 8dd992fb

drivers/target/target_core_sbc.c

+68 −53
Original line number Diff line number Diff line
@@ -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;

}