From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 13 Sep 2002 15:45:41 +0100 From: "Stephen C. Tweedie" Subject: Re: kiobuf interface / PG_locked flag Message-ID: <20020913154541.E17450@redhat.com> References: <3D8054D5.B385C83@scs.ch> <3D80B1C8.EE19E03D@earthlink.net> <20020912163308.I2273@redhat.com> <20020913124127.GB23303@artax.karlin.mff.cuni.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20020913124127.GB23303@artax.karlin.mff.cuni.cz>; from bulb@ucw.cz on Fri, Sep 13, 2002 at 02:41:27PM +0200 Sender: owner-linux-mm@kvack.org Return-Path: To: Jan Hudec , "Stephen C. Tweedie" , "Joseph A. Knapka" , Martin Maletinsky , linux-mm@kvack.org, kernelnewbies@nl.linux.org List-ID: Hi, On Fri, Sep 13, 2002 at 02:41:27PM +0200, Jan Hudec wrote: > Ref-counts protect from swapping out. But it's the PG_locked flag, that > protects from starting other IO. If you are writing, read must not > happen. If you are reading, nothing else at all must happen. So that's > the difference. map_use_kiobuf fault the pages in. lock_kiovec make > sure, that noone (else) is doing ANU IO on the pages. Depends on what semantics you want. There's nothing to stop a kiobuf from being modified in flight. All the app has to do is create a thread and modify the buffer from within that thread. --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-mm.org/