From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [REGRESSION v4.10-rc1] blkdev_issue_zeroout() returns -EREMOTEIO on the first call for SCSI device that doesn't support WRITE SAME To: "Martin K. Petersen" References: <20170203161239.GA3880@lst.de> <1e819f0d-ecdc-e54a-bd3d-17de2f71c8a7@kernel.dk> Cc: Christoph Hellwig , Junichi Nomura , "linux-block@vger.kernel.org" , linux-scsi , Chaitanya Kulkarni From: Jens Axboe Message-ID: <34e7f917-8fff-d8f9-c498-3431a27113ca@kernel.dk> Date: Fri, 3 Feb 2017 20:17:10 -0700 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 List-ID: On 02/03/2017 03:45 PM, Martin K. Petersen wrote: >>>>>> "Jens" == Jens Axboe writes: > >>> I think we should fix sd.c to only send WRITE SAME if either of the >>> variants are explicitly listed as supported through REPORT SUPPORTED >>> OPERATION CODES, or maybe through a whitelist if there are important >>> enough devices. > > Jens> Yep > > I hate it too. But the reason it's assumed on is that there is > essentially no heuristic that works. Just like we assume that READ > always works. > > Out of the ~200 devices I have access to in the lab: > > - 100% of the SAS/FC disk drives and SSDs support WRITE SAME > - Only 2 out of about 50 different drive models support RSOC > - About half of the arrays support WRITE SAME(10/16) > - None of the arrays I have support RSOC > > So even if we were to entertain using RSOC for "enterprise" transport > classes (which I concur would be nice for other reasons), it wouldn't > solve the WRITE SAME problem... We're at (almost) -rc7 time, we have to do more than hand wave about this. What's the plan for 4.10 final? -- Jens Axboe