linux-kernel - Re: [PATCH 02/14] FS-Cache: Recruit a couple of page flags for cache management

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Wed, 01 Aug 2007 09:27:13 +0100
From:	David Howells <dhowells@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	torvalds@...l.org, akpm@...l.org, steved@...hat.com,
	trond.myklebust@....uio.no, linux-fsdevel@...r.kernel.org,
	linux-cachefs@...hat.com, nfsv4@...ux-nfs.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 02/14] FS-Cache: Recruit a couple of page flags for cache management

Peter Zijlstra <peterz@...radead.org> wrote:

> Not sure its a good idea to overload page_has_private() with an
> overloadable page-flag. What if some future FS wants to use
> PG_owner_priv_2 for other purposes?

All that it means is that releasepage() and co will get called if a page is to
be released or invalidated that has that bit set.  I think that's something a
future FS could probably live with.

However, I do have to trigger a call to releasepage() and co *somehow*.

> Obviously filesystems cannot use these two page-flags if they want to be
> compatible with FS-cache, but need all filesystems be?

What do you mean?  That's why I went for the PG_owner_priv_* approach rather
than just naming the bits unto FS-Cache directly.

> (also, ouch! - 2 pageflags)

Yeah.  The consequence of having things asynchronous is that you have to find
signalling mechanisms to synchronise around the asynchronicity:-/

Furthermore, it occurs to me that I can't use PG_private or page->private to
store this information because I want to make isofs use caching, and those two
pieces of information are owned by the buffering code.

David
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/