From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH] extend e2fsprogs functionality to add EXT2_FLAG_DIRECT option Date: Tue, 12 Jan 2010 11:47:48 -0500 Message-ID: <20100112164748.GA26895@infradead.org> References: <4B4B84E2.1050508@redhat.com> <4B4C54DC.4040006@redhat.com> <4B4C6429.6090803@redhat.com> <4B4C67F5.1020009@redhat.com> <20100112122319.GA20596@infradead.org> <4B4C6B70.1050205@redhat.com> <20100112124600.GA7151@infradead.org> <4B4C7297.5030905@redhat.com> <20100112163828.GA14633@infradead.org> <4B4CA6A9.3030401@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Christoph Hellwig , Ric Wheeler , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org To: Michal Novotny Return-path: Received: from bombadil.infradead.org ([18.85.46.34]:52338 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751669Ab0ALQrt (ORCPT ); Tue, 12 Jan 2010 11:47:49 -0500 Content-Disposition: inline In-Reply-To: <4B4CA6A9.3030401@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Jan 12, 2010 at 05:43:21PM +0100, Michal Novotny wrote: > So, do you think the problem is in the Xen backend drivers and to make > it working right in Xen the driver fix is needed? Yes, the Xen blkback driver just submits I/O directly without using the right interfaces to force cache coherency. It might be relatively easy to hack a call in to flush all caches when it starts up, but given how it bypasses all abstractions it's almost impossible to give full coherency as if using the normal block device interfaces.