From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 7 Nov 2000 11:17:14 +0000 From: "Stephen C. Tweedie" Subject: Re: PATCH [2.4.0test10]: Kiobuf#02, fault-in fix Message-ID: <20001107111714.B1384@redhat.com> References: <20001102134021.B1876@redhat.com> <20001103232721.D27034@athlon.random> <20001106150539.A19112@redhat.com> <20001106171204.B22626@athlon.random> <20001106165416.A27036@redhat.com> <20001106233457.A1276@inspiron.random> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20001106233457.A1276@inspiron.random>; from andrea@suse.de on Mon, Nov 06, 2000 at 11:34:57PM +0100 Sender: owner-linux-mm@kvack.org Return-Path: To: Andrea Arcangeli Cc: "Stephen C. Tweedie" , Linus Torvalds , Rik van Riel , Ingo Molnar , linux-mm@kvack.org List-ID: Hi, On Mon, Nov 06, 2000 at 11:34:57PM +0100, Andrea Arcangeli wrote: > On Mon, Nov 06, 2000 at 04:54:16PM +0000, Stephen C. Tweedie wrote: > > About the implementation of the missing VM infrastructure for handling page > dirty at the physical pagecache layer, I'd suggest to change ramfs to use a new > PG_protected bitfield with the current semantics of PG_dirty, and to use > PG_dirty for the stuff that we must flush to disk. PG_dirty works for some cases. In particular, it works for any filesystems which can safely ignore the struct file * in the writepage address_space operation. However, for things like NFS, we cannot ever to arbitrary writeback to a file from the page cache --- we need the user context of the original write in order to establish the credentials for the server operation. That's why my current bug-fix patch just does the writepage at the end of the raw IO: it's a general fix which works for all mmap types. Once that is in place, we can think about extending it so that filesystems can provide a separate method for "flush" which honurs PG_dirty. For filesystems with such a flush method, marking a kiobuf dirty would simply involve setting PG_dirty, but for others (such as NFS) the mark_kiobuf_dirty would still have to do the full early writepage. Cheers, Stephen -- 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.eu.org/Linux-MM/