From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753404Ab2GPQSa (ORCPT ); Mon, 16 Jul 2012 12:18:30 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:36797 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753212Ab2GPQS1 (ORCPT ); Mon, 16 Jul 2012 12:18:27 -0400 Message-ID: <1342455503.3176.42.camel@dabdike.int.hansenpartnership.com> Subject: Re: [PATCH] sd: do not set changed flag on all unit attention conditions From: James Bottomley To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Date: Mon, 16 Jul 2012 17:18:23 +0100 In-Reply-To: <1342454772-9018-1-git-send-email-pbonzini@redhat.com> References: <1342454772-9018-1-git-send-email-pbonzini@redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2012-07-16 at 18:06 +0200, Paolo Bonzini wrote: > Right now, I/O will fail as soon as a unit attention condition is > detected on a unit with removable media. However, this is not > always necessary. There are some cases (such as "Capacity data > has changed") where no particular action is needed. On the > other hand, all problematic cases have to report at least one > of "No medium" and/or a "Medium may have changed", so restrict > our attention to those. > > This patch fixes resizing a removable medium with virtio-scsi. > > Signed-off-by: Paolo Bonzini > --- > drivers/scsi/scsi_lib.c | 7 +++++-- > 1 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index b583277..6d8ca08 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -843,8 +843,11 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) > } else if (sense_valid && !sense_deferred) { > switch (sshdr.sense_key) { > case UNIT_ATTENTION: > - if (cmd->device->removable) { > - /* Detected disc change. Set a bit > + if (cmd->device->removable && > + (sshdr.asc == 0x3a || > + (sshdr.asc == 0x28 && sshdr.ascq == 0x00))) { > + /* "No medium" or "Medium may have changed." > + * This means a disc change. Set a bit This type of change would likely cause a huge cascade of errors in real removable media devices. Under the MMC standards, which a lot of the older removable discs seem to follow, UNIT ATTENTION indicates either medium change or device reset (which we check for and eat lower down); we can't rely on them giving proper SBC-2 sense codes. If you want to pretend to be removable media, you have to conform to its standards. James