[PATCH 5/5] lio iblock: add support for REQ_CMP_AND_WRITE

michaelc
2014-10-16T05:37:32Z

From: Mike Christie <michaelc@cs.wisc.edu>

This patch has the iblock backing store use blkdev_issue_cmp_and_write
if the backing store device/queue supports it.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
---
drivers/target/target_core_iblock.c | 85 ++++++++++++++++++++++++++++-------
1 files changed, 68 insertions(+), 17 deletions(-)

diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index 7e6b857..cac928a 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -153,6 +153,11 @@ static int iblock_configure_device(struct se_device *dev)
*/
dev->dev_attrib.max_write_same_len = 0xFFFF;

+ /* convert from linux block layer 512 byte sector to our block size */
+ dev->dev_attrib.max_compare_and_write_len =
+ (q->limits.max_cmp_and_write_sectors << IBLOCK_LBA_SHIFT) /
+ dev->dev_attrib.hw_block_size;
+
if (blk_queue_nonrot(q))
dev->dev_attrib.is_nonrot = 1;

@@ -413,6 +418,67 @@ iblock_execute_sync_cache(struct se_cmd *cmd)
return 0;
}

+/*
+ * Convert the blocksize advertised to the initiator to the 512 byte
+ * units unconditionally used by the Linux block layer.
+ */
+static int iblock_get_lba_shift(struct se_cmd *cmd)
+{
+ struct se_device *dev = cmd->se_dev;
+
+ if (dev->dev_attrib.block_size == 4096)
+ return 3;
+ else if (dev->dev_attrib.block_size == 2048)
+ return 2;
+ else if (dev->dev_attrib.block_size == 1024)
+ return 1;
+ else
+ return 0;
+}
+
+static sense_reason_t
+iblock_execute_compare_and_write(struct se_cmd *cmd)
+{
+ struct block_device *bdev = IBLOCK_DEV(cmd->se_dev)->ibd_bd;
+ int ret, i = 0;
+ sector_t block_lba;
+ struct scatterlist *sg;
+ struct bio *bio;
+
+ block_lba = cmd->t_task_lba << iblock_get_lba_shift(cmd);
+
+ /* assumes SGLs are PAGE_SIZE */
+ bio = blkdev_setup_cmp_and_write(bdev, block_lba, GFP_KERNEL,
+ cmd->t_data_nents);
+ if (!bio) {
+ pr_err("blkdev_setup_cmp_and_write() failed\n");
+ return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+ }
+
+ for_each_sg(cmd->t_data_sg, sg, cmd->t_data_nents, i) {
+ ret = bio_add_pc_page(bdev_get_queue(bdev), bio, sg_page(sg),
+ sg->length, sg->offset);
+ if (ret != sg->length) {
+ bio_put(bio);
+ pr_err("bio_add_pc_page() failed\n");
+ return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+ }
+ }
+
+ ret = blkdev_issue_cmp_and_write(bio);
+ if (ret == -ECANCELED) {
+ pr_warn("Target/%s: Send MISCOMPARE check condition and sense\n",
+ cmd->se_dev->transport->name);
+ return TCM_MISCOMPARE_VERIFY;
+ } else if (ret < 0) {
+ pr_err("blkdev_issue_cmp_and_write() failed: %d\n", ret);
+ return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+ }
+
+ target_complete_cmd(cmd, GOOD);
+ return 0;
+}
+
static sense_reason_t
iblock_do_unmap(struct se_cmd *cmd, void *priv,
sector_t lba, sector_t nolb)
@@ -701,23 +767,7 @@ iblock_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
rw = READ;
}

- /*
- * Convert the blocksize advertised to the initiator to the 512 byte
- * units unconditionally used by the Linux block layer.
- */
- if (dev->dev_attrib.block_size == 4096)
- block_lba = (cmd->t_task_lba << 3);
- else if (dev->dev_attrib.block_size == 2048)
- block_lba = (cmd->t_task_lba << 2);
- else if (dev->dev_attrib.block_size == 1024)
- block_lba = (cmd->t_task_lba << 1);
- else if (dev->dev_attrib.block_size == 512)
- block_lba = cmd->t_task_lba;
- else {
- pr_err("Unsupported SCSI -> BLOCK LBA conversion:"
- " %u\n", dev->dev_attrib.block_size);
- return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
- }
+ block_lba = cmd->t_task_lba << iblock_get_lba_shift(cmd);

ibr = kzalloc(sizeof(struct iblock_req), GFP_KERNEL);
if (!ibr)
@@ -841,6 +891,7 @@ static struct sbc_ops iblock_sbc_ops = {
.execute_write_same = iblock_execute_write_same,
.execute_write_same_unmap = iblock_execute_write_same_unmap,
.execute_unmap = iblock_execute_unmap,
+ .execute_compare_and_write = iblock_execute_compare_and_write,
};

static sense_reason_t
--
1.7.1