From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 1/1] scsi: add Synology to 1024 sector blacklist Date: Wed, 13 Jan 2016 11:27:12 +0100 Message-ID: <56962680.6020303@redhat.com> References: <1452206045-18332-1-git-send-email-mchristi@redhat.com> <56953DEF.1050306@redhat.com> <1452677624.27508.70.camel@haakon3.risingtidesystems.com> <56961BC0.6090101@redhat.com> <1452678977.27508.82.camel@haakon3.risingtidesystems.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Received: from mail-wm0-f66.google.com ([74.125.82.66]:33601 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755216AbcAMK1S (ORCPT ); Wed, 13 Jan 2016 05:27:18 -0500 Received: by mail-wm0-f66.google.com with SMTP id u188so36004463wmu.0 for ; Wed, 13 Jan 2016 02:27:18 -0800 (PST) In-Reply-To: <1452678977.27508.82.camel@haakon3.risingtidesystems.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: "Nicholas A. Bellinger" Cc: mchristi@redhat.com, linux-scsi@vger.kernel.org On 13/01/2016 10:56, Nicholas A. Bellinger wrote: > Nope, or at least not in iblock_configure_device() code. > > The MAXIMUM TRANSFER LENGTH in block limits EVPD for IBLOCK is > queue_max_hw_sectors() * bdev_logical_block_size, and > queue_max_segments() is not considered atm. > > Is there a case where MTL needs to be the smaller of the two..? Given enough fragmentation of the t_data_sg, the actual MTL will be queue_max_segments() * PAGE_SIZE bytes. I think it's a bug in LIO that target_alloc_sgl always does order-0 allocation. But until that is fixed, LIO will be susceptible to this problem, at least for PSCSI backends (for BLOCK and FILEIO, the block and VFS layers can always split one I/O down to multiple requests). Paolo