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Commit 2237498f authored by Nicholas Bellinger's avatar Nicholas Bellinger
Browse files

target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout 



The people who are actively using iblock_execute_write_same_direct() are
doing so in the context of ESX VAAI BlockZero, together with
EXTENDED_COPY and COMPARE_AND_WRITE primitives.

In practice though I've not seen any users of IBLOCK WRITE_SAME for
anything other than VAAI BlockZero, so just using blkdev_issue_zeroout()
when available, and falling back to iblock_execute_write_same() if the
WRITE_SAME buffer contains anything other than zeros should be OK.

(Hook up max_write_zeroes_sectors to signal LBPRZ feature bit in
 target_configure_unmap_from_queue - nab)

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Mike Christie <mchristi@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 464fd641

drivers/target/target_core_device.c

+1 −1
Original line number Diff line number Diff line
@@ -851,7 +851,7 @@ bool target_configure_unmap_from_queue(struct se_dev_attrib *attrib, 
	attrib->unmap_granularity = q->limits.discard_granularity / block_size;

	attrib->unmap_granularity_alignment = q->limits.discard_alignment /

								block_size;

	attrib->unmap_zeroes_data = 0;

	attrib->unmap_zeroes_data = (q->limits.max_write_zeroes_sectors);

	return true;

}

EXPORT_SYMBOL(target_configure_unmap_from_queue);

drivers/target/target_core_iblock.c

+27 −17
Original line number Diff line number Diff line
@@ -86,6 +86,7 @@ static int iblock_configure_device(struct se_device *dev) 
	struct block_device *bd = NULL;

	struct blk_integrity *bi;

	fmode_t mode;

	unsigned int max_write_zeroes_sectors;

	int ret = -ENOMEM;



	if (!(ib_dev->ibd_flags & IBDF_HAS_UDEV_PATH)) {
@@ -129,6 +130,10 @@ static int iblock_configure_device(struct se_device *dev) 
	 * Enable write same emulation for IBLOCK and use 0xFFFF as

	 * the smaller WRITE_SAME(10) only has a two-byte block count.

	 */

	max_write_zeroes_sectors = bdev_write_zeroes_sectors(bd);

	if (max_write_zeroes_sectors)

		dev->dev_attrib.max_write_same_len = max_write_zeroes_sectors;

	else

		dev->dev_attrib.max_write_same_len = 0xFFFF;



	if (blk_queue_nonrot(q))
@@ -415,28 +420,31 @@ iblock_execute_unmap(struct se_cmd *cmd, sector_t lba, sector_t nolb) 
}



static sense_reason_t

iblock_execute_write_same_direct(struct block_device *bdev, struct se_cmd *cmd)

iblock_execute_zero_out(struct block_device *bdev, struct se_cmd *cmd)

{

	struct se_device *dev = cmd->se_dev;

	struct scatterlist *sg = &cmd->t_data_sg[0];

	struct page *page = NULL;

	int ret;

	unsigned char *buf, zero = 0x00, *p = &zero;

	int rc, ret;



	if (sg->offset) {

		page = alloc_page(GFP_KERNEL);

		if (!page)

			return TCM_OUT_OF_RESOURCES;

		sg_copy_to_buffer(sg, cmd->t_data_nents, page_address(page),

				  dev->dev_attrib.block_size);

	}

	buf = kmap(sg_page(sg)) + sg->offset;

	if (!buf)

		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

	/*

	 * Fall back to block_execute_write_same() slow-path if

	 * incoming WRITE_SAME payload does not contain zeros.

	 */

	rc = memcmp(buf, p, cmd->data_length);

	kunmap(sg_page(sg));



	ret = blkdev_issue_write_same(bdev,

	if (rc)

		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;



	ret = blkdev_issue_zeroout(bdev,

				target_to_linux_sector(dev, cmd->t_task_lba),

				target_to_linux_sector(dev,

					sbc_get_write_same_sectors(cmd)),

				GFP_KERNEL, page ? page : sg_page(sg));

	if (page)

		__free_page(page);

				GFP_KERNEL, false);

	if (ret)

		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
@@ -472,8 +480,10 @@ iblock_execute_write_same(struct se_cmd *cmd) 
		return TCM_INVALID_CDB_FIELD;

	}



	if (bdev_write_same(bdev))

		return iblock_execute_write_same_direct(bdev, cmd);

	if (bdev_write_zeroes_sectors(bdev)) {

		if (!iblock_execute_zero_out(bdev, cmd))

			return 0;

	}



	ibr = kzalloc(sizeof(struct iblock_req), GFP_KERNEL);

	if (!ibr)