On Thu, Jun 02 2016 at 11:06pm -0400,
Martin K. Petersen <martin.petersen@xxxxxxxxxx> wrote:
> >>>>> "Christoph" == Christoph Hellwig <hch@xxxxxxxxxxxxx> writes:
>
> Christoph> As part of that I also removed the strange EOPNOTSUPP ignore,
> Christoph> but Mike reverted it just because it changed something in the
> Christoph> dm testsuite.
>
> Mike?
Yes? ;)
Seems there is some serious confusion going on here. The entirety of
hch's post (to which you quoted a subset) makes little sense to me.
shli's patch builds ontop of latest blk-lib.c code yet hch said this::
"We've split blkdev_issue_discard into __blkdev_issue_discard and a
small wrapper around in for 4.7, so this will need a bit of an update."
And hch never "removed the strange EOPNOTSUPP ignore". He preserved it
(see his commit 38f25255330's "return ret != -EOPNOTSUPP ? ret : 0;"
that I adjusted in commit bbd848e0f -- _and_ he expanded it to eat the
early return that I restored).
So I can only infer that hch is still missing why my revert fixes
historic blkdev_issue_discard() behavior that his commit regressed.
Please read commit bbd848e0f's header. That at least details the early
vs late -EOPNOTSUPP blkdev_issue_discard() return.
But all that nuance aside, AFAICT my commit bbd848e0f ("block: reinstate
early return of -EOPNOTSUPP from blkdev_issue_discard") really has
_nothing_ to do with the issue shli is addressing with his fix.
> Christoph> I still believe we should never ignore it in this helper, and
> Christoph> only do so in callers that believe it's the right thing.
>
> Yeah.
Hmm...
You agreed to what hch said there about how we should probably always
return EOPNOTSUPP but then you immediately elaborated with details that
mean you don't agree:
> I really wish EOPNOTSUPP would just go away except for ioctl callers.
> Now that we have real bi_error I don't understand why we need it.
But hch was originally in favor of _always_ dropping EOPNOTSUPP on the
floor (that is what his commit 38f25255330 did). Then he said he
disagrees with these interfaces playing games with masking EOPNOTSUPP --
to which you seemingly really don't agree. Unless I'm completely
misreading you.
Anyway, shli is at least making it so that blkdev_issue_zerout() can
fallback to other mechanisms as needed.
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