From: Mike Christie <mchristi@xxxxxxxxxx>
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@xxxxxxxxxx>
---
drivers/target/target_core_iblock.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index c9c07e3..a886447 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -417,8 +417,39 @@ 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)
+{
+ 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;
@@ -443,6 +474,9 @@ 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;
--
1.8.3.1
--
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