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Wed, 26 Feb 2025 12:09:38 +0000 (GMT) Message-ID: <0d4afccf-3b62-485e-9bde-61463f6cbb95@linux.ibm.com> Date: Wed, 26 Feb 2025 17:39:37 +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: [PATCHv2 1/6] blk-sysfs: remove q->sysfs_lock for attributes which don't need it To: Christoph Hellwig , Ming Lei Cc: linux-block@vger.kernel.org, dlemoal@kernel.org, axboe@kernel.dk, gjoyce@ibm.com References: <20250218082908.265283-1-nilay@linux.ibm.com> <20250218082908.265283-2-nilay@linux.ibm.com> <20250218084622.GA11405@lst.de> <00742db2-08b3-4582-b741-8c9197ffaced@linux.ibm.com> <20250224144929.GA2205@lst.de> Content-Language: en-US From: Nilay Shroff In-Reply-To: <20250224144929.GA2205@lst.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 2CFFYeu05mpLB_oyHteJhcu1rvx1xIch X-Proofpoint-GUID: 2CFFYeu05mpLB_oyHteJhcu1rvx1xIch X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-02-26_02,2025-02-26_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 priorityscore=1501 suspectscore=0 mlxlogscore=783 spamscore=0 phishscore=0 mlxscore=0 adultscore=0 malwarescore=0 bulkscore=0 clxscore=1015 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502100000 definitions=main-2502260096 On 2/24/25 8:19 PM, Christoph Hellwig wrote: > On Sat, Feb 22, 2025 at 08:44:51PM +0800, Ming Lei wrote: >> IMO, it is fine to read it lockless without READ_ONCE/WRITE_ONCE because >> disk->nr_zones is defined as 'unsigned int', which won't return garbage >> value anytime. >> >> But I don't object if you want to change to READ_ONCE/WRITE_ONCE. > > It changes every time the disk capacity changes. And on the (uncommon) > reformats. So the best locking would be the same as for the disk > capacity. > So does that mean we shall use bdev->bd_size_lock or disk->open_mutex here? Thanks, --Nilay