target/iblock: Add WRITE_SAME w/ UNMAP=0 emulation support
This patch adds support for emulation of WRITE_SAME w/ UNMAP=0 within
iblock_execute_write_same() backend code.
The emulation uses a bio_add_page() call for each sector, and by default
enforces a limit of max_write_same_len=0xFFFF (65536) sectors following
what scsi_debug reports per default for MAXIMUM WRITE SAME LENGTH.
It also sets max_write_same_len to the operational default at setup ->
iblock_configure_device() time.
(hch: Move unmap logic into iblock_execute_write_same_unmap + add
check for single sector SGLs in iblock_execute_write_same)
(mkp: Update comment for 0xFFFF magic constant)
(nab: drop left-over max_write_same_len check in iblock_execute_write_same)
Cc: Christoph Hellwig <hch@lst.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index 53f4501..6646046 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -151,6 +151,11 @@
pr_debug("IBLOCK: BLOCK Discard support available,"
" disabled by default\n");
}
+ /*
+ * Enable write same emulation for IBLOCK and use 0xFFFF as
+ * the smaller WRITE_SAME(10) only has a two-byte block count.
+ */
+ dev->dev_attrib.max_write_same_len = 0xFFFF;
if (blk_queue_nonrot(q))
dev->dev_attrib.is_nonrot = 1;
@@ -375,17 +380,20 @@
return ret;
}
+static struct bio *iblock_get_bio(struct se_cmd *, sector_t, u32);
+static void iblock_submit_bios(struct bio_list *, int);
+static void iblock_complete_cmd(struct se_cmd *);
+
static sense_reason_t
-iblock_execute_write_same(struct se_cmd *cmd)
+iblock_execute_write_same_unmap(struct se_cmd *cmd)
{
struct iblock_dev *ib_dev = IBLOCK_DEV(cmd->se_dev);
- int ret;
+ int rc;
- ret = blkdev_issue_discard(ib_dev->ibd_bd, cmd->t_task_lba,
- spc_get_write_same_sectors(cmd), GFP_KERNEL,
- 0);
- if (ret < 0) {
- pr_debug("blkdev_issue_discard() failed for WRITE_SAME\n");
+ rc = blkdev_issue_discard(ib_dev->ibd_bd, cmd->t_task_lba,
+ spc_get_write_same_sectors(cmd), GFP_KERNEL, 0);
+ if (rc < 0) {
+ pr_warn("blkdev_issue_discard() failed: %d\n", rc);
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
}
@@ -393,6 +401,69 @@
return 0;
}
+static sense_reason_t
+iblock_execute_write_same(struct se_cmd *cmd)
+{
+ struct iblock_req *ibr;
+ struct scatterlist *sg;
+ struct bio *bio;
+ struct bio_list list;
+ sector_t block_lba = cmd->t_task_lba;
+ unsigned int sectors = spc_get_write_same_sectors(cmd);
+
+ sg = &cmd->t_data_sg[0];
+
+ if (cmd->t_data_nents > 1 ||
+ sg->length != cmd->se_dev->dev_attrib.block_size) {
+ pr_err("WRITE_SAME: Illegal SGL t_data_nents: %u length: %u"
+ " block_size: %u\n", cmd->t_data_nents, sg->length,
+ cmd->se_dev->dev_attrib.block_size);
+ return TCM_INVALID_CDB_FIELD;
+ }
+
+ ibr = kzalloc(sizeof(struct iblock_req), GFP_KERNEL);
+ if (!ibr)
+ goto fail;
+ cmd->priv = ibr;
+
+ bio = iblock_get_bio(cmd, block_lba, 1);
+ if (!bio)
+ goto fail_free_ibr;
+
+ bio_list_init(&list);
+ bio_list_add(&list, bio);
+
+ atomic_set(&ibr->pending, 1);
+
+ while (sectors) {
+ while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
+ != sg->length) {
+
+ bio = iblock_get_bio(cmd, block_lba, 1);
+ if (!bio)
+ goto fail_put_bios;
+
+ atomic_inc(&ibr->pending);
+ bio_list_add(&list, bio);
+ }
+
+ /* Always in 512 byte units for Linux/Block */
+ block_lba += sg->length >> IBLOCK_LBA_SHIFT;
+ sectors -= 1;
+ }
+
+ iblock_submit_bios(&list, WRITE);
+ return 0;
+
+fail_put_bios:
+ while ((bio = bio_list_pop(&list)))
+ bio_put(bio);
+fail_free_ibr:
+ kfree(ibr);
+fail:
+ return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+}
+
enum {
Opt_udev_path, Opt_readonly, Opt_force, Opt_err
};
@@ -701,6 +772,7 @@
.execute_rw = iblock_execute_rw,
.execute_sync_cache = iblock_execute_sync_cache,
.execute_write_same = iblock_execute_write_same,
+ .execute_write_same_unmap = iblock_execute_write_same_unmap,
.execute_unmap = iblock_execute_unmap,
};