From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CB8CD21101 for ; Mon, 18 Sep 2023 18:42:19 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id D640322038; Mon, 18 Sep 2023 18:42:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1695062537; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=u0/5tXDr/+zZG5DOnZsO5Nl+pfdm9qTkOFBP2JNaICQ=; b=DhjMrLma4oOxFndMq/PfF00nlYAmMcA2N7VDW07xe8CQsNPWPQplml00iY2eajbZXYOX0E fNjXBWblBtqTwUBhlNSYi/T4LLswLzqQrCsboZJtGMDx3YAVXjUcXvrwy1ryc9RCRIIWuW rXqN6CV04C1Olt5dHevp/kUBE2vZp2M= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1695062537; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=u0/5tXDr/+zZG5DOnZsO5Nl+pfdm9qTkOFBP2JNaICQ=; b=KnKnqJcJs6VWh5PZE7jfSKkavEP525/NYCUT3sH3MY6NHT0g59ENQlmOdJxE9lXbmOt30s MnA10pkOqw/RM4Ag== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id EFEC713480; Mon, 18 Sep 2023 18:42:15 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id FL/qNgeaCGW4NwAAMHmgww (envelope-from ); Mon, 18 Sep 2023 18:42:15 +0000 Message-ID: Date: Mon, 18 Sep 2023 20:42:09 +0200 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC v2 00/10] bdev: LBS devices support to coexist with buffer-heads Content-Language: en-US To: Matthew Wilcox , Luis Chamberlain Cc: hch@infradead.org, djwong@kernel.org, dchinner@redhat.com, kbusch@kernel.org, sagi@grimberg.me, axboe@fb.com, brauner@kernel.org, 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 References: <20230915213254.2724586-1-mcgrof@kernel.org> From: Hannes Reinecke In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 9/18/23 20:15, Matthew Wilcox wrote: > On Mon, Sep 18, 2023 at 10:12:04AM -0700, Luis Chamberlain wrote: >> On Fri, Sep 15, 2023 at 10:51:12PM +0100, Matthew Wilcox wrote: >>> 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. >> >> Coverage on sunsetting buffer-heads talk by LWN: >> >> https://lwn.net/Articles/931809/ >> >> "the apparent conclusion from the session: the buffer-head layer will be >> converted to use folios internally while minimizing changes visible to >> the filesystems using it. Only single-page folios will be used within >> this new buffer-head layer. Any other desires, he said, can be addressed >> later after this problem has been solved." > > Other people said that. Not me. I said it was fine for single > buffer_head per folio. And my patchset proves that to be the case. Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), Geschäftsführer: Ivo Totev, Andrew Myers, Andrew McDonald, Martje Boudien Moerman