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Commit bfd9a53e authored by Akinobu Mita's avatar Akinobu Mita Committed by Nicholas Bellinger
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target/rd: Don't pass incomplete scatterlist entries to sbc_dif_verify_* 



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 problem can be fixed by chaining protection information scatterlist
at creation time.  For the architectures which don't support sg chaining
(i.e. !CONFIG_ARCH_HAS_SG_CHAIN), fix it by allocating temporary
scatterlist if needed.

Signed-off-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Cc: Sagi Grimberg <sagig@dev.mellanox.co.il>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: target-devel@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 054922bb

drivers/target/target_core_rd.c

+64 −3
Original line number Diff line number Diff line
@@ -139,10 +139,22 @@ static int rd_allocate_sgl_table(struct rd_dev *rd_dev, struct rd_dev_sg_table * 
	unsigned char *p;



	while (total_sg_needed) {

		unsigned int chain_entry = 0;



		sg_per_table = (total_sg_needed > max_sg_per_table) ?

			max_sg_per_table : total_sg_needed;



		sg = kzalloc(sg_per_table * sizeof(struct scatterlist),

#ifdef CONFIG_ARCH_HAS_SG_CHAIN



		/*

		 * Reserve extra element for chain entry

		 */

		if (sg_per_table < total_sg_needed)

			chain_entry = 1;



#endif /* CONFIG_ARCH_HAS_SG_CHAIN */



		sg = kcalloc(sg_per_table + chain_entry, sizeof(*sg),

				GFP_KERNEL);

		if (!sg) {

			pr_err("Unable to allocate scatterlist array"
@@ -150,7 +162,16 @@ static int rd_allocate_sgl_table(struct rd_dev *rd_dev, struct rd_dev_sg_table * 
			return -ENOMEM;

		}



		sg_init_table(sg, sg_per_table);

		sg_init_table(sg, sg_per_table + chain_entry);



#ifdef CONFIG_ARCH_HAS_SG_CHAIN



		if (i > 0) {

			sg_chain(sg_table[i - 1].sg_table,

				 max_sg_per_table + 1, sg);

		}



#endif /* CONFIG_ARCH_HAS_SG_CHAIN */



		sg_table[i].sg_table = sg;

		sg_table[i].rd_sg_count = sg_per_table;
@@ -390,11 +411,13 @@ 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_npages __maybe_unused;

	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);
@@ -407,7 +430,45 @@ static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd, dif_verify dif_verify) 
	prot_sg = &prot_table->sg_table[prot_page -

					prot_table->page_start_offset];



#ifndef CONFIG_ARCH_HAS_SG_CHAIN



	prot_npages = DIV_ROUND_UP(prot_offset + sectors * se_dev->prot_length,

				   PAGE_SIZE);



	/*

	 * Allocate temporaly contiguous scatterlist entries if 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) {

					kfree(prot_sg);

					return rc;

				}

				sg_unmark_end(&prot_sg[i - 1]);

			}

			prot_sg[i] = prot_table->sg_table[prot_page + i -

						prot_table->page_start_offset];

		}

	}



#endif /* !CONFIG_ARCH_HAS_SG_CHAIN */



	rc = dif_verify(cmd, cmd->t_task_lba, sectors, 0, prot_sg, prot_offset);

	if (need_to_release)

		kfree(prot_sg);



	return rc;

}