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Thu, 20 Aug 2026 09:58:35 +0000 X-Mizu-Trace-ID: 30b66ec55db78dc2 X-Migadu-Flow: FLOW_OUT Message-ID: <9c699958-c5b6-4aff-adf2-7c27a91cf4c2@linux.dev> Date: Thu, 20 Aug 2026 17:58:26 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: cui.tao@linux.dev, Yu Kuai , Christoph Hellwig , Jan Kara , Ming Lei , Jonathan Corbet , Shuah Khan , Coly Li , Kent Overstreet , Alasdair Kergon , Mike Snitzer , Mikulas Patocka , Benjamin Marzinski , Song Liu , Li Nan , Xiao Ni , Pankaj Gupta , Dan Williams , Vishal Verma , Dave Jiang , Alison Schofield , Ira Weiny , Andreas Gruenbacher , Matthew Wilcox , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-bcache@vger.kernel.org, dm-devel@lists.linux.dev, linux-raid@vger.kernel.org, nvdimm@lists.linux.dev, virtualization@lists.linux.dev, gfs2@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH v3 2/3] blk-cgroup: store blkcg in bio instead of blkg To: Yu Kuai , Jens Axboe , Tejun Heo , Josef Bacik , Johannes Weiner , =?UTF-8?Q?Michal_Koutn=C3=BD?= References: <20260818070641.756747-1-yukuai@kernel.org> <20260818070641.756747-3-yukuai@kernel.org> From: Tao Cui In-Reply-To: <20260818070641.756747-3-yukuai@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: hb4xd1n55ih5pmg9smwwzrpr8nkaxqf1 X-Rspamd-Queue-Id: 3E67640002 X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1787219917-304885 X-HE-Meta: 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 CUi+ncUJ NSoYLexfV4piVTz707iWErbR4/bSDbVrYoDR49o0JiVYZkSySS+RBdRIYjBhMNha2Fvewar9xG9WxyC/SZUoLLnx80Jmc0r8T42o249B94m7TnHv/LOmZ2DT09/Z8ytnxmrSf6o3U5aHD1np5s+UkJLzSTTRvue6whjfJ+9vTds2WYVMWv9P7YSeJLGYi5VNa60oTiQns4ZcTn4qgK1rSUcwv24BWKbTnfcVcMOVS2hzDhUD+gbOJVJNRFlHMvNmeY01hy8Q76k3FFLqG6Jkx4F2HbvJgtooX+e07Ta00mUox7es4EMSi59IPe7r3C9xr7NN8JSdSmgh8cT58y8YBJi0KT8gWzDysuv98GioI1yoOMlt0U2i5HTMm6CT91UzBVaIp Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 在 2026/8/18 15:06, Yu Kuai 写道: > A bio currently stores and pins a queue-local blkg. This forces bio > association and remap paths to look up or create a blkg even when no > blkcg policy will use the bio, and ties the stored state to the current > block device. > > Store and reference the queue-independent blkcg in the bio instead. Add > helpers that lazily look up or create the queue-local blkg when a policy > needs it, and pin the result until the bio changes devices or releases > its cgroup state. > > If blkg creation fails while walking down the hierarchy, use the closest > available ancestor and update the bio's blkcg association before recording > the blkg reference. This keeps later CSS ID hash lookups matched with the > pinned blkg. > > Keep lookup-only users from creating missing blkgs. A pinned blkg remains > in the queue hash until the bio drops its reference, so allow the bio to > recover it from the hash after the blkg starts dying. Rename the bio > association helpers to describe the blkcg state they now store. Reviewed-by: Tao Cui