Re: Getting FS access events

[Linus Torvalds]

On Tue, 15 May 2001, Chris Wedgwood wrote:
>
> On Tue, May 15, 2001 at 12:13:13AM -0700, Linus Torvalds wrote:
>
>     We should not create crap code just because we _can_.
>
> How about removing code?

Absolutely. It's not all that often that we can do it, but when we can,
it's the best thing in the world.

> In 2.5.x is we move fs metadata into the pagecache, do we even need a
> buffer cache anymore? Can't we just ditch it completely and make all
> device access raw?

Yes and no.

Yes, it would be nice.

But no, I doubt we'll move _all_ metadata into the page-cache. I doubt,
for example, that we'll find people re-doing all the other filesystems. So
even if ext2 was page-cache only, what about all the 35 other filesystems
out there in the standard sources, never mind others that haven't been
integrated (XFS, ext3 etc..).

Yeah, I know. Some of them already do not use the buffer cache at all (the
network filesystems come to mind ;), but even so..

Looks like there are 19 filesystems that use the buffer cache right now:

	grep -l bread fs/*/*.c | cut -d/ -f2 | sort -u | wc

So quite a bit of work involved.

But on the whole I'm definitely hoping that yes, we'll relegate the
"buffer_head" to be mainly just for IO, and not be a first-class caching
entity at all. It's just that I think it will take a _loooong_ time until
we actually reach that noble goal completely.

		Linus