From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=37306 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1ObEvW-0005bz-Be for qemu-devel@nongnu.org; Tue, 20 Jul 2010 11:40:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1ObEvR-0001SE-4Q for qemu-devel@nongnu.org; Tue, 20 Jul 2010 11:40:14 -0400 Received: from mail-yx0-f173.google.com ([209.85.213.173]:46679) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1ObEvR-0001Ry-2A for qemu-devel@nongnu.org; Tue, 20 Jul 2010 11:40:09 -0400 Received: by yxn35 with SMTP id 35so1533537yxn.4 for ; Tue, 20 Jul 2010 08:40:07 -0700 (PDT) Message-ID: <4C45C355.2000204@codemonkey.ws> Date: Tue, 20 Jul 2010 10:40:05 -0500 From: Anthony Liguori MIME-Version: 1.0 References: <1279639056-20465-1-git-send-email-Jes.Sorensen@redhat.com> In-Reply-To: <1279639056-20465-1-git-send-email-Jes.Sorensen@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: [PATCH] Disable O_DIRECT for physical CDROM/DVD drives List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jes.Sorensen@redhat.com Cc: qemu-devel@nongnu.org On 07/20/2010 10:17 AM, Jes.Sorensen@redhat.com wrote: > From: Jes Sorensen > > O_DIRECT (cache=none) requires sector alignment, however the physical > sector size of CDROM/DVD drives is 2048, as opposed to most disk > devices which use 512. QEMU is hard coding 512 all over the place, so > allowing O_DIRECT for CDROM/DVD devices does not work. > > Signed-off-by: Jes Sorensen > Wouldn't a better solution be to have a cdrom_read/cdrom_write hook that did the appropriate bouncing? Silently disabling something a user explicitly asked for is not a good option. In the very least, it should error out entirely. Regards, Anthony Liguori > --- > block/raw-posix.c | 5 +++++ > 1 files changed, 5 insertions(+), 0 deletions(-) > > diff --git a/block/raw-posix.c b/block/raw-posix.c > index 291699f..0ea79b6 100644 > --- a/block/raw-posix.c > +++ b/block/raw-posix.c > @@ -1139,6 +1139,11 @@ static int cdrom_open(BlockDriverState *bs, const char *filename, int flags) > BDRVRawState *s = bs->opaque; > > s->type = FTYPE_CD; > + if (flags& BDRV_O_NOCACHE) { > + fprintf(stderr, "Disabling unsupported O_DIRECT (cache=none) for " > + "CDROM/DVD device (%s)\n", filename); > + flags&= ~BDRV_O_NOCACHE; > + } > > /* open will not fail even if no CD is inserted, so add O_NONBLOCK */ > return raw_open_common(bs, filename, flags, O_NONBLOCK); >