geom->access problem and workaround

[Warner Losh]

On Fri, Mar 23, 2018 at 3:30 AM, Poul-Henning Kamp <phk at phk.freebsd.dk>
wrote:

> --------
> In message <5e416eb6-0e79-1419-f09a-eb747215dc28 at FreeBSD.org>, Andriy
> Gapon writes:
> >On 12/03/2018 20:07, Poul-Henning Kamp wrote:
> >> If we want to have an architectural sound way to do slow operations
> >> before any "user-I/O" is initiated, the right way to do so is to
> >> define new BIO_OPEN and BIO_CLOSE  operation, and insist via asserts
> >> than all BIO_{READ|WRITE|DELETE} are wrapped in these.
>
> >What do you think?
>
> I don't see that changing anything...
>
> GEOM rests on a set of assumptions, if you violate them, you get panics.


I agree. The cd panic is a problem in the cd driver where it bogusly uses
runccb in a context that can't sleep.

Warner