Re: Linux Buffer Cache Does Not Support Mirroring

Jeff V. Merkey (jmerkey@timpanogas.com)
Tue, 02 Nov 1999 09:56:28 -0700


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.

Jeff

kernel@kvack.org wrote:
>
> On Mon, 1 Nov 1999, Jeff V. Merkey wrote:
>
> > What everyone is side-stepping is that the interface between the drivers
> > and the buffer cache is incestuous
>
> What do you mean by incestuous -- if you mean that they depend on it,
> you're thinking of things in the wrong way. Think of the buffer_head as a
> block io tag. The block drivers themselves don't interact with the buffer
> cache, they interact with requests.
>
> > -- this prevents folks from building
> > async I/O based FS's on Linux. The solution is not a simple one -- the
> > drivers and buffer cache interface needs to be changed to elimnate these
> > dependencies so.
>
> So you're incapable of making use of b_end_io to complete an async io
> request? Wow.
>
> -ben
>
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