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Petersen" , "Darrick J. Wong" , Kirill Tkhai , axboe@kernel.dk, bob.liu@oracle.com, agk@redhat.com, snitzer@redhat.com, dm-devel@redhat.com, song@kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, Chaitanya.Kulkarni@wdc.com, ming.lei@redhat.com, osandov@fb.com, jthumshirn@suse.de, minwoo.im.dev@gmail.com, damien.lemoal@wdc.com, andrea.parri@amarulasolutions.com, hare@suse.com, tj@kernel.org, ajay.joshi@wdc.com, sagi@grimberg.me, dsterba@suse.com, bvanassche@acm.org, dhowells@redhat.com, asml.silence@gmail.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v7 0/6] block: Introduce REQ_ALLOCATE flag for REQ_OP_WRITE_ZEROES From: "Martin K. Petersen" Organization: Oracle Corporation References: <158157930219.111879.12072477040351921368.stgit@localhost.localdomain> <69c0b8a4-656f-98c4-eb55-2fd1184f5fc9@virtuozzo.com> <67d63190-c16f-cd26-6b67-641c8943dc3d@virtuozzo.com> <20200319102819.GA26418@infradead.org> <20200325162656.GJ29351@magnolia> <20200325163223.GA27156@infradead.org> <20200326092935.GA6478@infradead.org> Date: Thu, 26 Mar 2020 10:34:42 -0400 In-Reply-To: <20200326092935.GA6478@infradead.org> (Christoph Hellwig's message of "Thu, 26 Mar 2020 02:29:35 -0700") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1.92 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9571 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 suspectscore=0 spamscore=0 mlxlogscore=923 adultscore=0 phishscore=0 mlxscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2003260113 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9571 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 malwarescore=0 priorityscore=1501 mlxscore=0 bulkscore=0 clxscore=1015 impostorscore=0 phishscore=0 suspectscore=0 mlxlogscore=965 spamscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2003260113 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Christoph, > That's why I don't like the whole flags game very much. I'd rather > have REQ_OP_WRITE_ZEROES as the integrity operation that gurantees > zeroing, and a REQ_ALLOCATE that doesn't guarantee zeroing, just some > deterministic state of the blocks. I just worry about the proliferation of identical merging and splitting code throughout the block stack as we add additional single-range, no payload operations (Verify, etc.). I prefer to enforce the semantics in the LLD and not in the plumbing. But I won't object to a separate REQ_OP_ALLOCATE if you find the resulting code duplication acceptable. -- Martin K. Petersen Oracle Linux Engineering