From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 16 May 2007 08:53:41 -0400 From: Chris Mason Subject: Re: [PATCH 1 of 2] block_page_mkwrite() Implementation V2 Message-ID: <20070516125341.GS26766@think.oraclecorp.com> References: <20070318233008.GA32597093@melbourne.sgi.com> <18993.1179310769@redhat.com> <1179317360.2859.225.camel@shinybook.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1179317360.2859.225.camel@shinybook.infradead.org> Sender: owner-linux-mm@kvack.org Return-Path: To: David Woodhouse Cc: David Howells , David Chinner , lkml , linux-mm , linux-fsdevel List-ID: On Wed, May 16, 2007 at 08:09:19PM +0800, David Woodhouse wrote: > On Wed, 2007-05-16 at 11:19 +0100, David Howells wrote: > > The start and end points passed to block_prepare_write() delimit the region of > > the page that is going to be modified. This means that prepare_write() > > doesn't need to fill it in if the page is not up to date. > > Really? Is it _really_ going to be modified? Even if the pointer > userspace gave to write() is bogus, and is going to fault half-way > through the copy_from_user()? This is why there are so many variations on copy_from_user that zero on faults. One way or another, the prepare_write/commit_write pair are responsible for filling it in. -chris -- 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: email@kvack.org