[OpenAFS-devel] Issues with my precache patch (was: Documentation
for fs precache)
Phillip Moore
w.phillip.moore@gmail.com
Tue, 19 Oct 2010 14:21:18 -0400
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Well, if this simple patch to the current pioctl can be made without all
that overhead, then someone else can fix this, unfortunately. I thought
this would be relatively simple, and it's a fix I don't really need
personally. Sorry to be selfish...
The real question is: do I need a new pioctl for this? I'm just modifying
the existing code and changing it's behavior.
On Tue, Oct 19, 2010 at 2:08 PM, Jeffrey Altman <
jaltman@secure-endpoints.com> wrote:
> On 10/19/2010 2:02 PM, Phillip Moore wrote:
> >
> > That means I will need a new kernel module installed in order to test
> > this, doesn't it?
> >
> > Is there anything I need to worry about if I change
> > DECL_PIOCTL(PPrecache) to behave more
> > like DECL_PIOCTL(PSetCachingThreshold)?
> >
> > The change seems pretty obvious, but this is the first time (OK, in
> > about 13 years) that I've touched any of the code in the kernel module.
>
> Be very careful about modifying pioctls. They are effectively RPCs and
> you can't be sure that the clients (userland fs) and servers (kernel
> modules) will be updates at the same time. You are in most cases going
> to need to request the allocation of new pioctl numbers from the
> registrar and implement the revised pioctl independently from the
> existing implementation which might or might not be removed.
>
> Jeffrey Altman
>
>
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<div><br></div>Well, if this simple patch to the current pioctl can be made=
without all that overhead, then someone else can fix this, unfortunately. =
=A0I thought this would be relatively simple, and it's a fix I don'=
t really need personally. =A0Sorry to be selfish...<div>
<br></div><div>The real question is: do I need a new pioctl for this? =A0I&=
#39;m just modifying the existing code and changing it's behavior.<br><=
br><div class=3D"gmail_quote">On Tue, Oct 19, 2010 at 2:08 PM, Jeffrey Altm=
an <span dir=3D"ltr"><<a href=3D"mailto:jaltman@secure-endpoints.com">ja=
ltman@secure-endpoints.com</a>></span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex;"><div class=3D"im">On 10/19/2010 2:02 PM, Ph=
illip Moore wrote:<br>
><br>
> That means I will need a new kernel module installed in order to test<=
br>
> this, doesn't it?<br>
><br>
> Is there anything I need to worry about if I change<br>
> =A0DECL_PIOCTL(PPrecache) to behave more<br>
> like DECL_PIOCTL(PSetCachingThreshold)?<br>
><br>
> The change seems pretty obvious, but this is the first time (OK, in<br=
>
> about 13 years) that I've touched any of the code in the kernel mo=
dule.<br>
<br>
</div>Be very careful about modifying pioctls. =A0They are effectively RPCs=
and<br>
you can't be sure that the clients (userland fs) and servers (kernel<br=
>
modules) will be updates at the same time. =A0You are in most cases going<b=
r>
to need to request the allocation of new pioctl numbers from the<br>
registrar and implement the revised pioctl independently from the<br>
existing implementation which might or might not be removed.<br>
<font color=3D"#888888"><br>
Jeffrey Altman<br>
<br>
</font></blockquote></div><br></div>
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