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Commit 07b63196 authored by Mike Christie's avatar Mike Christie Committed by Nicholas Bellinger
Browse files

target/iblock: pass WRITE_SAME to device if possible 



This patch has iblock pass the WRITE_SAME command to
the device for offloading if possible. It is similar to what is
done for UNMAP/discards, except that we export a large max write same
value to the initiator, and then rely on the block layer to
break it up into multiple requests if it cannot fit into one.

v2.

- Drop file backend changes and move helper function to
iblock backend.

Signed-off-by: default avatarMike Christie <mchristi@redhat.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent e3416ab2

drivers/target/target_core_iblock.c

+34 −0
Original line number Diff line number Diff line
@@ -412,9 +412,40 @@ iblock_execute_unmap(struct se_cmd *cmd, sector_t lba, sector_t nolb) 
	return 0;

}



static sense_reason_t

iblock_execute_write_same_direct(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;



	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);

	}



	ret = blkdev_issue_write_same(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);

	if (ret)

		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;



	target_complete_cmd(cmd, GOOD);

	return 0;

}



static sense_reason_t

iblock_execute_write_same(struct se_cmd *cmd)

{

	struct block_device *bdev = IBLOCK_DEV(cmd->se_dev)->ibd_bd;

	struct iblock_req *ibr;

	struct scatterlist *sg;

	struct bio *bio;
@@ -439,6 +470,9 @@ 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);



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

	if (!ibr)

		goto fail;