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Fri, 17 Apr 2026 12:36:23 +0000 (GMT) Message-ID: <7009b70f-bc19-4034-9426-2b94522afcbd@linux.ibm.com> Date: Fri, 17 Apr 2026 18:06:21 +0530 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH blktests v2] nvme/068: add a test for multipath delayed removal To: John Garry , shinichiro.kawasaki@wdc.com, linux-block@vger.kernel.org Cc: linux-nvme@lists.infradead.org, kch@nvidia.com References: <20260417094854.2135472-1-john.g.garry@oracle.com> Content-Language: en-US From: Nilay Shroff In-Reply-To: <20260417094854.2135472-1-john.g.garry@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: UTYyiHuSLvEGyYe10GSWWW4hDNCap6Si X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDE3MDEyNCBTYWx0ZWRfX0Z68G0Yhgoze bNfeJ0+gHQxXc4mGF3KSFIHdV7ESBRFktGCoFUS1nktNgmtnBpcZQdgrjcpAMdie22uxGEAC13o s22UNzN9bluy7QfYNccQuA4/ogkzizZnIrIXePN7bavc5skXS9rpYZ80E6U7EL5nV+YfvZcdA4k lwxodXxhWTEfbnZ23Q/gj85RjbZryBsqJ1lD3E6OOHaR0EfcH/ru7gHyM/hAm7Tw8OOCuVLKjzv qFxYy8Pv+JVHC+wfJGYdQw38Rxk96fPMK9jrqqdKA3o/Uzd1Qfwar4EHuzLDk+nYtwfPxfEIqTc fKbXGkOw3t6xjeRTdaSpDnIcxPYFRgT8vHPK8izoPe2mMgQEdZh/Q3jGPdwhdg3X/2FDeIO4u1G kWr3OapAXnin/uTjZlWm4nPyDQHNVVp1BMFYkrIiTue8HBGyeS0T/WACb4D36RrE6CwtDW1H+gS r2CBCWXyCPTtpw6TmIg== X-Proofpoint-ORIG-GUID: UTYyiHuSLvEGyYe10GSWWW4hDNCap6Si X-Authority-Analysis: v=2.4 cv=W60IkxWk c=1 sm=1 tr=0 ts=69e2294a cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=Ikd4Dj_1AAAA:8 a=yPCof4ZbAAAA:8 a=VnNF1IyMAAAA:8 a=vFfYFJvREM-Gq1xf8H4A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-17_01,2026-04-17_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 clxscore=1015 priorityscore=1501 spamscore=0 bulkscore=0 adultscore=0 phishscore=0 lowpriorityscore=0 suspectscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604070000 definitions=main-2604170124 On 4/17/26 3:18 PM, John Garry wrote: > For NVMe multipath, the delayed removal feature allows the multipath > gendisk to remain present when all available paths are gone. The purpose of > this feature is to ensure that we keep the gendisk for intermittent path > failures. > > The delayed removal works on a timer - when all paths are gone, a timer is > kicked off; once the timer expires and no paths have returned, the gendisk > is removed. > > When all paths are gone and the gendisk is still present, all reads and > writes to the disk are queued. If a path returns before the timer > expiration, the timer canceled and the queued IO is submitted; > otherwise they fail when the timer expires. > > This testcase covers two scenarios in separate parts: > a. test that IOs submitted after all paths are removed (and do not return) > fail > b. test that IOs submitted between all paths removed and a path > returning succeed > > During the period of the timer being active, it must be ensured that the > nvme-core module is not removed. Otherwise the driver may not be present > to handle the timeout expiry. The kernel ensures this by taking a > reference to the module. Ideally, we would try to remove the module during > this test to prove that this is not possible (and the kernel behaves as > expected), but that module will probably not be removable anyway due to > many references. To test this feature, check that the refcount of the > nvme-core module is incremented when the delayed timer is active. > > Reviewed-by: Chaitanya Kulkarni > Signed-off-by: John Garry Looks good to me: Reviewed-by: Nilay Shroff