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a=rsa-sha256; c=relaxed/relaxed; d=stgolabs.net; s=dreamhost; t=1744306710; bh=YwxaJTg4VJbIYIQ6s+Ic7Nv7sEsm9q3MKFC0yNU64hU=; h=Date:From:To:Cc:Subject:Content-Type; b=MgKhBiI69HXrwf01/pCiEXtBE6JBwR9Y1Z5yfP3KyiTkwq2mmN5P0NyW2pRhAY1qq YRo6dPXEpIV72q3digPVEezjwF3sCVOkocRnQhlUZDLEhOrpKaPERGmzF8eTUVZoDL dZNPOCb2vetDceHq1sYqwupZIBXk5U/E1d6DiY6XtTn3V+jLKkVGfLkkWtC15L3AQi JFG4NetVjuKrUx2mY0vEEXoJL4YfT6UIjj6lwkQA1KcW1wZ//zKsSfUH78sogpbkYD S8CgcAdfyPBa7PH6fK1a7gEMXpPOIspd6R0zwok7cIml0IyPtZhMClXoHw3losIOZ9 LUW8qJUc51SIA== Date: Thu, 10 Apr 2025 10:38:17 -0700 From: Davidlohr Bueso To: Jan Kara Cc: Luis Chamberlain , brauner@kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, riel@surriel.com, willy@infradead.org, hannes@cmpxchg.org, oliver.sang@intel.com, david@redhat.com, axboe@kernel.dk, hare@suse.de, david@fromorbit.com, djwong@kernel.org, ritesh.list@gmail.com, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org, gost.dev@samsung.com, p.raghav@samsung.com, da.gomez@samsung.com Subject: Re: [PATCH v2 2/8] fs/buffer: try to use folio lock for pagecache lookups Message-ID: <20250410173817.5cdlnnooxwgbkpov@offworld> Mail-Followup-To: Jan Kara , Luis Chamberlain , brauner@kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, riel@surriel.com, willy@infradead.org, hannes@cmpxchg.org, oliver.sang@intel.com, david@redhat.com, axboe@kernel.dk, hare@suse.de, david@fromorbit.com, djwong@kernel.org, ritesh.list@gmail.com, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org, gost.dev@samsung.com, p.raghav@samsung.com, da.gomez@samsung.com References: <20250410014945.2140781-1-mcgrof@kernel.org> <20250410014945.2140781-3-mcgrof@kernel.org> Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20220429 On Thu, 10 Apr 2025, Jan Kara wrote: >I'd rather do: > > if (atomic) { > spin_lock(&bd_mapping->i_private_lock); > folio_locked = false; > } else { > folio_lock(folio); > } > Fine with me. I just think the trylock for the atomic scenario would have given greater chances of successful migration, but at a lack of determinism, of course. >I'd actually love to do something like: > > if (atomic) { > if (!folio_trylock(folio)) > bail... > } else { > folio_lock(folio); > } > >but that may be just too radical this point and would need some serious >testing how frequent the trylock failures are. No point in blocking this >series with it. So just go with the deterministic use of i_private_lock for >atomic users for now. This acually crossed my mind, but I also considered the scheme a little too much for this series.