Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965808AbaGPSul (ORCPT ); Wed, 16 Jul 2014 14:50:41 -0400 Received: from mx2.parallels.com ([199.115.105.18]:46368 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965526AbaGPSuf convert rfc822-to-8bit (ORCPT ); Wed, 16 Jul 2014 14:50:35 -0400 From: James Bottomley To: "martin.petersen@oracle.com" CC: "linux-kernel@vger.kernel.org" , "hch@infradead.org" , "devel@linuxdriverproject.org" , "apw@canonical.com" , "kys@microsoft.com" , "stable@vger.kernel.org" , "linux-scsi@vger.kernel.org" , "ohering@suse.com" , "jasowang@redhat.com" Subject: Re: [PATCH 4/8] Drivers: scsi: storvsc: Filter WRITE_SAME_16 Thread-Topic: [PATCH 4/8] Drivers: scsi: storvsc: Filter WRITE_SAME_16 Thread-Index: AQHPoSYn2vh72TcerE+9u7O+On3hT5ujgK+A Date: Wed, 16 Jul 2014 18:50:31 +0000 Message-ID: <1405536631.3165.23.camel@dabdike.int.hansenpartnership.com> References: <20140709084300.GD6012@infradead.org> <1404935792.2184.5.camel@dabdike.int.hansenpartnership.com> <2f3ae589e6f149acbe4c5dd79f905971@BY2PR03MB299.namprd03.prod.outlook.com> <1404944843.2184.8.camel@dabdike.int.hansenpartnership.com> <20140711063216.GA20660@infradead.org> <328b7a6174ef4dd8a54a7db5ac959834@BY2PR03MB299.namprd03.prod.outlook.com> <20140716110111.GA7382@infradead.org> <20140716173827.GB20528@infradead.org> <1405533734.3165.12.camel@dabdike.int.hansenpartnership.com> In-Reply-To: Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [50.46.103.107] Content-Type: text/plain; charset=US-ASCII Content-ID: <81F91A0C3A4F654E84482637DCDD08D7@sw.swsoft.com> 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 Wed, 2014-07-16 at 14:45 -0400, Martin K. Petersen wrote: > >>>>> "James" == James Bottomley writes: > > >> I don't have a problem with a BLIST_PREFER_UNMAP flag or something > >> like that. But BLIST_TRY_VPD_PAGES seems more generally useful and it > >> does fix the problem at hand. That's why I went that route. > > James> Hang on ... unless we apply Christoph or my fix, we'll get the > James> same issue with every raid driver (that's about 10 I think) that > James> set no_write_same when they hit a >2TB RAID volume, > > no_write_same is set for all the RAID controller drivers (54b2b50c20a6). > > If a WRITE SAME(10/16) command fails and the UNMAP bit is not set we'll > set no_write_same=1 and disable REQ_WRITE_SAME support. > > If a WRITE SAME(10/16) command fails and the UNMAP bit is set we'll > disable REQ_DISCARD support. > > Not sure where the 10 vs. 16 byte 2TB limitation comes into play here? It's the code we identified in sd.c:read_capacity_16(): if (buffer[14] & 0x80) { /* LBPME */ sdkp->lbpme = 1; if (buffer[14] & 0x40) /* LBPRZ */ sdkp->lbprz = 1; sd_config_discard(sdkp, SD_LBP_WS16); } If the inquiry shows LBPME set, we'll do write same regardless of the no_write_same bit. That's why for SPC-2 devices it only shows up on >2TB devices because they force RC16. James -- 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/