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target/iblock: pass WRITE_SAME to device if possible

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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: Mike Christie <mchristi@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Mike Christie 2016-02-24 13:56:33 -06:00 committed by Nicholas Bellinger
parent e3416ab2d1
commit 07b6319687
1 changed files with 34 additions and 0 deletions
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34
drivers/target/target_core_iblock.c
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@ -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;