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References: <20190125021107.4595-1-zhangxiaoxu5@huawei.com>
 <CAMeeMh_=UVGwo-=9WtBXRmiHTXnLAswqis97bM-aiuwnzPU0QQ@mail.gmail.com>
 <20190128221441.GA24102@redhat.com> <yq1lg34f4i7.fsf@oracle.com>
 <CAMeeMh85T_qui=LWd0u=b_oMN5XLqowqkvLuYGBM2Ae6tS-mzg@mail.gmail.com> <20190131103924.GA22503@infradead.org>
In-Reply-To: <20190131103924.GA22503@infradead.org>
From:   John Dorminy <jdorminy@redhat.com>
Date:   Thu, 31 Jan 2019 14:41:52 -0500
Message-ID: <CAMeeMh-uxiee7rKutnr3jrMjzkc8=R2Y3DPPBLvLYjqSwjfi_w@mail.gmail.com>
Subject: Re: block: Fix a WRITE SAME BUG_ON
To:     Christoph Hellwig <hch@infradead.org>
Cc:     "Martin K. Petersen" <martin.petersen@oracle.com>,
        Mike Snitzer <snitzer@redhat.com>,
        Zhang Xiaoxu <zhangxiaoxu5@huawei.com>, axboe@kernel.dk,
        linux-block@vger.kernel.org, dm-devel@redhat.com,
        Alasdair G Kergon <agk@redhat.com>
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On Thu, Jan 31, 2019 at 5:39 AM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Wed, Jan 30, 2019 at 09:08:50AM -0500, John Dorminy wrote:
> > (I use WRITE_SAME to fill devices with a particular pattern in order
> > to catch failures to initialize disk structures appropriately,
> > personally, but it's just for convenience/speed.)
>
> How do you use it?  We don't have a user interface to generate
> REQ_OP_WRITE_SAME requests.

A not-checked-in test module, similar to Zhang Xiaoxu's reproducer,
exposing a sysfs node to trigger filling a block device with a test
pattern.