From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BC5B21B28A for ; Fri, 15 Sep 2023 21:51:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=OjslU8SUhgdXrUcRZYaungvHohmhC3Ah4nEZHFd9adc=; b=bZ9XHGdy3Y7tSqtQxGArjIHu99 8kyAqRjluuRgG3KHxex8I4xiq3tAQyfHXU6OUOYO4aOnVd9K7ypyRYVTJcyS7lC5Q8sFGMcDdQfcP krALeBAXuf+bzNrpPgO3aVJSLmR3k6Z5eobP3l2hv7fUvDznXWgfaknRvsZo/0M2/LNu0J4f1ATOn IfT2RYKBE23DIUd3dXYHTNHJyh1z78S/SAZypfU4TRtFENyEl9ydqQRvWUxLAsrF0brhLBxqy6ygl oHRcvq4RgkBebxdsz6lv7FjpijkXALeo0ut2wL+jdzHUsIo/bRxm8/kM97kpZwHQG0f6FVhVJKOZu q/jXYcKA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qhGiW-00CHbh-9D; Fri, 15 Sep 2023 21:51:12 +0000 Date: Fri, 15 Sep 2023 22:51:12 +0100 From: Matthew Wilcox To: Luis Chamberlain Cc: hch@infradead.org, djwong@kernel.org, dchinner@redhat.com, kbusch@kernel.org, sagi@grimberg.me, axboe@fb.com, brauner@kernel.org, hare@suse.de, ritesh.list@gmail.com, rgoldwyn@suse.com, jack@suse.cz, ziy@nvidia.com, ryan.roberts@arm.com, patches@lists.linux.dev, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, p.raghav@samsung.com, da.gomez@samsung.com, dan.helmick@samsung.com Subject: Re: [RFC v2 00/10] bdev: LBS devices support to coexist with buffer-heads Message-ID: References: <20230915213254.2724586-1-mcgrof@kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230915213254.2724586-1-mcgrof@kernel.org> On Fri, Sep 15, 2023 at 02:32:44PM -0700, Luis Chamberlain wrote: > However, an issue is that disabling CONFIG_BUFFER_HEAD in practice is not viable > for many Linux distributions since it also means disabling support for most > filesystems other than btrfs and XFS. So we either support larger order folios > on buffer-heads, or we draw up a solution to enable co-existence. Since at LSFMM > 2023 it was decided we would not support larger order folios on buffer-heads, Um, I didn't agree to that. If block size is equal to folio size, there are no problems supporting one buffer head per folio. In fact, we could probably go up to 8 buffer heads per folio without any trouble (but I'm not signing up to do that work).