Mike Christie wrote:
For FC there is code like the fc_rport stuff which exports a sysfs
interface but also does a lot more like probing and queue blocking.
And the iSCSI class does do a lot more now too. This just has not been
updated. It handles the userspace to kernel communication, session and
connection sysfs interface setup,
Great. Exactly.
Structures like the fc_rport and iscsi_session are managed by the
transport classes so scsi-ml never knows about them (except for that
scanning bug). And it is possible to share them between HW and software
or partial software solutions. I do agree for some iscsi sitautions
having a layer over the eh or command exection where the transport
really is more of a layer like your design would be nice (I am not
refferring to the code duplication though becuase iSCSI would like some
of yrou fixes :), but at the same time there are places where code can
be shared between a interface that hides the lower level details and one
that implements them in software. Maybe it is not this way for SAS though.
Adaptec's SAS stuff implements the standard high level SCSI model as an
API, which is a pretty decent direction for SCSI long term: provides a
transport-independent execute-scsi-command high level hook (along with
the other task management functions), and hides the transport details
for the most part.
That's fine, and works for iSCSI as well.
I just disagree that we need to have two concurrent APIs for SCSI,
completely separate from each other, and mildly duplicating each other's
code.
The current SCSI code will morph in the proper direction given time and
love. Segregating generic [SPI | FC | SAS | iSCSI | ATA | RAID | ...]
transport layer code into their own modules -- the transport classes and
associated libs -- will point out the sore spots where scsi-ml needs
changes. This approach also implies we improve the existing scsi-ml
where needed, rather than the proposed "if legacy, let it bitrot" approach.
Jeff
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