Re: Linux Buffer Cache Does Not Support Mirroring

Jeff V. Merkey (jmerkey@timpanogas.com)
Tue, 02 Nov 1999 14:10:06 -0700


Cool. I will look at this.

Jeff

Gadi Oxman wrote:
>
> Jeff,
>
> BTW, the RAID code is also using the async b_end_io callback, to
> get a success/failure report on each I/O transaction. Cross
> reference raid5_end_request() in raid5.c and raid1_end_request()
> in raid1.c, which are installed as b_end_io callbacks in the
> buffers which go to the real block drivers. In the RAID-5 case,
> the callback function (called at the interrupt context) then wakes
> up a kernel thread for further processing.
>
> Gadi
>
> On Tue, 2 Nov 1999, Jeff V. Merkey wrote:
>
> >
> > Alan,
> >
> > I'll try this.
> >
> > Jeff
> >
> > Alan Cox wrote:
> > >
> > > > I looked at the brw_page code. While everyone calls this an "async"
> > > > interface, in fact, it uses the same semantic as a sync interface and
> > > > does not allow support for callbacks.
> > >
> > > Its a function pointer. What else do you need other than passing a parameter
> > > void * or similar to get more flexibility.
> > >
> > > You can use the callback to wake a thread, you can schedule a task after
> > > IRQ completion, you can do stuff directly on the IRQ callback if you are
> > > careful about deadlocks.
> > >
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