Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261655AbVCIVha (ORCPT ); Wed, 9 Mar 2005 16:37:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262450AbVCIVgP (ORCPT ); Wed, 9 Mar 2005 16:36:15 -0500 Received: from e35.co.us.ibm.com ([32.97.110.133]:17650 "EHLO e35.co.us.ibm.com") by vger.kernel.org with ESMTP id S261655AbVCIVfP (ORCPT ); Wed, 9 Mar 2005 16:35:15 -0500 Subject: Re: [PATCH] 2.6.10 - direct-io async short read bug From: Badari Pulavarty To: Andrew Morton Cc: suparna@in.ibm.com, Daniel McNeil , sebastien.dugue@bull.net, "linux-aio@kvack.org" , Linux Kernel Mailing List In-Reply-To: <20050309115348.2b86b765.akpm@osdl.org> References: <1110189607.11938.14.camel@frecb000686> <20050307223917.1e800784.akpm@osdl.org> <20050308090946.GA4100@in.ibm.com> <1110302614.24286.61.camel@dyn318077bld.beaverton.ibm.com> <1110309508.24286.74.camel@dyn318077bld.beaverton.ibm.com> <1110324434.6521.23.camel@ibm-c.pdx.osdl.net> <1110326043.24286.134.camel@dyn318077bld.beaverton.ibm.com> <20050309040757.GY27331@ca-server1.us.oracle.com> <20050309152047.GA4588@in.ibm.com> <20050309115348.2b86b765.akpm@osdl.org> Content-Type: text/plain Organization: Message-Id: <1110403885.24286.216.camel@dyn318077bld.beaverton.ibm.com> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.2 (1.2.2-5) Date: 09 Mar 2005 13:31:26 -0800 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1581 Lines: 36 On Wed, 2005-03-09 at 11:53, Andrew Morton wrote: > Suparna Bhattacharya wrote: > > > > > Solaris, which does forcedirectio as a mount option, actually > > > will do buffered I/O on the trailing part. Consider it like a bounce > > > buffer. That way they don't DMA the trailing data and succeed the I/O. > > > The I/O returns actual bytes till EOF, just like read(2) is supposed to. > > > Either this or a fully DMA'd number 4 is really what we should > > > do. If security can only be solved via a bounce buffer, who cares? If > > > the user created themselves a non-aligned file to open O_DIRECT, that's > > > their problem if the last part-sector is negligably slower. > > > > If writes/truncates take care of zeroing out the rest of the sector > > on disk, might we still be OK without having to do the bounce buffer > > thing ? > > We can probably rely on the rest of the sector outside i_size being zeroed > anyway. Because if it contains non-zero gunk then the fs already has a > problem, and the user can get at that gunk with an expanding truncate and > mmap() anyway. > Rest of the sector or rest of the block ? Are you implying that, we already do this, so there is no problem reading beyond EOF to user buffer ? Or we need to zero out the userbuffer beyond EOF ? Thanks, Badari - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/