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Wed, 28 Jan 2026 09:35:38 +0000 (GMT) Message-ID: <54eee632-0489-4f30-9c2a-ebde4bd30f88@linux.ibm.com> Date: Wed, 28 Jan 2026 15:05:36 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] nvme: stop using AWUPF To: John Garry , hch@lst.de, kbusch@kernel.org, sagi@grimberg.me, axboe@fb.com Cc: martin.petersen@oracle.com, linux-nvme@lists.infradead.org References: <20260128082623.3945303-1-john.g.garry@oracle.com> Content-Language: en-US From: Nilay Shroff In-Reply-To: <20260128082623.3945303-1-john.g.garry@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=Gr1PO01C c=1 sm=1 tr=0 ts=6979d870 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VwQbUJbxAAAA:8 a=yPCof4ZbAAAA:8 a=VnNF1IyMAAAA:8 a=vuobHaRB_AI57xyFkLQA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: bHNTmFDgyRstRUUXd8P4f2wHf8f1SL_G X-Proofpoint-ORIG-GUID: bHNTmFDgyRstRUUXd8P4f2wHf8f1SL_G X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTI4MDA3NSBTYWx0ZWRfXxnsele98P5dt RBRjrvT9gYc02raJOCqsc+vv9ySVot7rgi3IcEk04YdxInYS8yrxESe17tgvPrj5SoE3LHzBWtZ owGN+BK5URxn8ryFjQ7xt0B3dFzQftErMyLlVz+j3ZjOv2Cq8AJ4ayGIN/JxNz41CkQeUEECAYv Su+NF5TRywDmEFeJG6uK3lyTegVAYw8EMDzWXtv9E+KJtBsDgGomlcEbhBqmC5Bkqns5hxnprtH R5vqTt2LQwy178bYBGrmMeqDCPqluhX43HHDTM/YSdBHwiKNFjE6kdc9yNSLCbCaUP1QHAa1t3M nmvYW2o/gQbuSnNTBDB5zo4juuSumNf2rfDSij6W1jWPuJeMkLqIfPodKg056lirQgONSTzKHDD bsMY/eX2tLr3tFCw2YRWrKCROGkdh0INZVmiSVvDEXZEaW2NKbSgzme14xf/TABGNkn2kN40c56 GtX5ckQe3rFQbmtjv6g== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-01-28_01,2026-01-27_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 clxscore=1011 lowpriorityscore=0 suspectscore=0 impostorscore=0 phishscore=0 malwarescore=0 adultscore=0 spamscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2601150000 definitions=main-2601280075 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260128_013556_101754_2DDFAB30 X-CRM114-Status: GOOD ( 21.45 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 1/28/26 1:56 PM, John Garry wrote: > As described at [0], much of the atomic write parts of the specification > are lacking. > > For now, there is nothing which we can do in software about the lack of > a dedicated NVMe write atomic command. > > As for reading the atomic write limits, it is felt that the per-namespace > values are mostly properly specified and it is assumed that they are > properly implemented. > > The specification of NAWUPF is quite clear. However the specification of > NABSPF is less clear. The lack of clarity in NABSPF comes from deciding > whether NABSPF applies when NSABP is 0 - it is assumed that NSABPF does > not apply when NSABP is 0. > > As for the per-controller AWUPF, how this value applies to shared > namespaces is missing in the specification. Furthermore, the value is in > terms of logical blocks, which is an NS entity. > > Since AWUPF is so poorly defined, stop using it already together. > Hopefully this will force vendors to implement NAWUPF support always. > > Note that AWUPF not only effects atomic write support, but also the > physical block size reported for the device. > > To help users know this restriction, log an info message per NS. > > [0] https://lore.kernel.org/linux-nvme/20250707141834.GA30198@lst.de/ > > Signed-off-by: John Garry > --- Looks good to me. Tested this patch on NVMe device reporting non-zero NAWUPF (and zero AWUPF), as well as on device reporting non-zero AWUPF. In both cases, the patch works as expected. Tested-by: Nilay Shroff Reviewed-by: Nilay Shroff