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target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout 

The people who are actively using iblock_execute_write_same_direct() are
doing so in the context of ESX VAAI BlockZero, together with
EXTENDED_COPY and COMPARE_AND_WRITE primitives.

In practice though I've not seen any users of IBLOCK WRITE_SAME for
anything other than VAAI BlockZero, so just using blkdev_issue_zeroout()
when available, and falling back to iblock_execute_write_same() if the
WRITE_SAME buffer contains anything other than zeros should be OK.

(Hook up max_write_zeroes_sectors to signal LBPRZ feature bit in
 target_configure_unmap_from_queue - nab)

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Mike Christie <mchristi@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
zero-colors
Nicholas Bellinger 2017-04-11 22:21:47 -07:00
parent 464fd6419c
commit 2237498f0b
2 changed files with 28 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/target/target_core_device.c
View File

@ -851,7 +851,7 @@ bool target_configure_unmap_from_queue(struct se_dev_attrib *attrib,
attrib->unmap_granularity = q->limits.discard_granularity / block_size;
attrib->unmap_granularity_alignment = q->limits.discard_alignment /
block_size;
attrib->unmap_zeroes_data = 0;
attrib->unmap_zeroes_data = (q->limits.max_write_zeroes_sectors);
return true;
}
EXPORT_SYMBOL(target_configure_unmap_from_queue);

44
drivers/target/target_core_iblock.c
View File

@ -86,6 +86,7 @@ static int iblock_configure_device(struct se_device *dev)
struct block_device *bd = NULL;
struct blk_integrity *bi;
fmode_t mode;
unsigned int max_write_zeroes_sectors;
int ret = -ENOMEM;
if (!(ib_dev->ibd_flags & IBDF_HAS_UDEV_PATH)) {
@ -129,7 +130,11 @@ static int iblock_configure_device(struct se_device *dev)
* 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;
max_write_zeroes_sectors = bdev_write_zeroes_sectors(bd);
if (max_write_zeroes_sectors)
dev->dev_attrib.max_write_same_len = max_write_zeroes_sectors;
else
dev->dev_attrib.max_write_same_len = 0xFFFF;
if (blk_queue_nonrot(q))
dev->dev_attrib.is_nonrot = 1;
@ -415,28 +420,31 @@ 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)
iblock_execute_zero_out(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;
unsigned char *buf, zero = 0x00, *p = &zero;
int rc, 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);
}
buf = kmap(sg_page(sg)) + sg->offset;
if (!buf)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
/*
* Fall back to block_execute_write_same() slow-path if
* incoming WRITE_SAME payload does not contain zeros.
*/
rc = memcmp(buf, p, cmd->data_length);
kunmap(sg_page(sg));
ret = blkdev_issue_write_same(bdev,
if (rc)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
ret = blkdev_issue_zeroout(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);
GFP_KERNEL, false);
if (ret)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
@ -472,8 +480,10 @@ 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);
if (bdev_write_zeroes_sectors(bdev)) {
if (!iblock_execute_zero_out(bdev, cmd))
return 0;
}
ibr = kzalloc(sizeof(struct iblock_req), GFP_KERNEL);
if (!ibr)