From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from westrelay02.boulder.ibm.com (westrelay02.boulder.ibm.com [9.17.195.11]) by e33.co.us.ibm.com (8.12.10/8.12.9) with ESMTP id j4IN0ImD702854 for ; Wed, 18 May 2005 19:00:18 -0400 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by westrelay02.boulder.ibm.com (8.12.10/NCO/VER6.6) with ESMTP id j4IN0I1o157426 for ; Wed, 18 May 2005 17:00:18 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11/8.13.3) with ESMTP id j4IN0I0h009707 for ; Wed, 18 May 2005 17:00:18 -0600 Subject: Re: page flags ? From: Badari Pulavarty In-Reply-To: <20050518145644.717afc21.akpm@osdl.org> References: <1116450834.26913.1293.camel@dyn318077bld.beaverton.ibm.com> <20050518145644.717afc21.akpm@osdl.org> Content-Type: text/plain Message-Id: <1116456143.26913.1303.camel@dyn318077bld.beaverton.ibm.com> Mime-Version: 1.0 Date: 18 May 2005 15:42:25 -0700 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: linux-mm@kvack.org, linux-fsdevel List-ID: On Wed, 2005-05-18 at 14:56, Andrew Morton wrote: > Badari Pulavarty wrote: > > > > Does anyone know what this page-flag is used for ? I see some > > references to this in AFS. > > > > Is it possible for me to use this for my own use in ext3 ? > > (like delayed allocations ?) Any generic routines/VM stuff > > expects me to use this only for a specific purpose ? > > > > #define PG_fs_misc 9 /* Filesystem specific bit */ > > > > It's identical to PG_checked, added by David Howells' > provide-a-filesystem-specific-syncable-page-bit.patch > > IIRC we decided to expand the definition of PG_checked to mean > "a_ops-private, fs-defined page flag". I guess if/when that patch is > merged we'll do a kernel-wide s/PG_checked/PG_fs_misc/. > > And ext3 is already using that flag. :( Is it possible to get yet another PG_fs_specific flag ? Reasons for it are: - I need this for supporting delayed allocation on ext3. Me, Ted and Suparna thought about it for a while to see we can workaround it. So far, I haven't found a clean way. - useful for other folks currently overloading page->private for this purpose. May be then, we can make most filesystems use mpage routines (since they assume page->private is for bufferheads ?) Thanks, Badari -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org