Re: [PATCH 5/6] nvmet: add verify emulation support for file-ns

Chaitanya Kulkarni
2022-07-06T04:10:07Z

On 7/5/22 01:36, Christoph Hellwig wrote:
> On Thu, Jun 30, 2022 at 02:14:05AM -0700, Chaitanya Kulkarni wrote:
>> For now, there is no way to map verify operation to the VFS layer API.
>> This patch emulates verify operation by offloading it to the workqueue
>> and reading the data using vfs layer APIs for both buffered io and
>> direct io mode.
>
> What does this buy us? I'm generally not too happy about adding
> actualy logic to nvmet, it is supposed to mostly just pass through
> operations support by block device or files.

When using file based backends for NVMeOF and lio (lio patch is
outstanding) I'm emulating (please let me know if you prefer other
terminology) verify command with read operation on the file,
this allows user to send read command and keep target compatible
with the block device namespace for verify support. In absence of
that file-backed fabrics targets will not support the verify
command ... or you want a generic file read helper to be used
for this scenario that is consumed by the nvmet/lio target ?

does that answer your question ?

-ck