2022-04-16 01:07:59

by Christoph Hellwig

Subject: [PATCH 01/27] target: remove an incorrect unmap zeroes data deduction

For block devices, the SCSI target drivers implements UNMAP as calls to
blkdev_issue_discard, which does not guarantee zeroing just because
Write Zeroes is supported.

Note that this does not affect the file backed path which uses
fallocate to punch holes.

Fixes: 2237498f0b5c ("target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout")
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Martin K. Petersen <[email protected]>
---
drivers/target/target_core_device.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 44bb380e7390c..fa866acef5bb2 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -850,7 +850,6 @@ 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 = !!(q->limits.max_write_zeroes_sectors);
return true;
}
EXPORT_SYMBOL(target_configure_unmap_from_queue);
--
2.30.2

2022-04-16 02:06:41

by Chaitanya Kulkarni

Subject: Re: [PATCH 01/27] target: remove an incorrect unmap zeroes data deduction

On 4/14/22 21:52, Christoph Hellwig wrote:
> For block devices, the SCSI target drivers implements UNMAP as calls to
> blkdev_issue_discard, which does not guarantee zeroing just because
> Write Zeroes is supported.
>
> Note that this does not affect the file backed path which uses
> fallocate to punch holes.
>
> Fixes: 2237498f0b5c ("target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout")
> Signed-off-by: Christoph Hellwig <[email protected]>
> Reviewed-by: Martin K. Petersen <[email protected]>

Not a good assumption to have for sure.

Looks good.

Reviewed-by: Chaitanya Kulkarni <[email protected]>

-ck