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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>
This commit is contained in:
Nicholas Bellinger 2012-11-07 20:08:38 -08:00
parent 773cbaf746
commit f6970ad31d
1 changed files with 79 additions and 7 deletions
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86
drivers/target/target_core_iblock.c
View File

@ -151,6 +151,11 @@ static int iblock_configure_device(struct se_device *dev)
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 @@ err:
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 @@ iblock_execute_write_same(struct se_cmd *cmd)
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 @@ static struct sbc_ops iblock_sbc_ops = {
.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,
};