Re: [PATCH 10/28] FS-Cache: Recruit a couple of page flags for cache management [try #2]

[David Howells]

Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote:

> I'd much prefer if you would handle this in the filesystem, and have it
> set PG_private whenever fscache needs to receive a callback, and DTRT
> depending on whether PG_fscache etc. is set or not.

That's tricky and slower[*].  One of the things I want to do is to modify
iso9660 to do be able to do caching, but PG_private is 'owned' by the generic
buffer cache code.

[*] though perhaps not significantly.

> Also, this wait_on_page_fscache_write / end_page_fscache_write stuff
> seems like it would belong in your fscache headers rather than generic
> mm code (ditto for your PG_fscache checks in the page allocator -- you
> should use their PG_owner_priv_? names for that).

I suppose that's reasonable, though I do want to mention the PG_fscache* bits
in linux/page-flags.h so that anyone looking at those bits to select one to
use can easily see a reason they might not want to.

David
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