From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 93628C4332F for ; Wed, 16 Nov 2022 13:43:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238667AbiKPNnJ (ORCPT ); Wed, 16 Nov 2022 08:43:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54802 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233130AbiKPNmw (ORCPT ); Wed, 16 Nov 2022 08:42:52 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 70F6E1E3FC for ; Wed, 16 Nov 2022 05:41:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1668606113; h=from:from:reply-to:subject:subject: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=Hthprm1ypSC4H9RqIYyAtXvnaUxVWoTWmoLjvcjOG60=; b=CGWZq7lEj1Ygr7kTa4/yIczxGXBa5kiigPxUBk/WB9syRbal4KqMwN4JWxjrdCiXinYYyB 4lx1LY3mcuTilEtrqqEnNHWgkDmXFkzmZG62zC5U6aY8Jh847s/eaasxouVzLRlp/YKmX4 INMNOLzkKViEa8vS3v2o4CRLeg8tKZo= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-529-OEYROdlKO_qh-fNyr-TMBw-1; Wed, 16 Nov 2022 08:41:46 -0500 X-MC-Unique: OEYROdlKO_qh-fNyr-TMBw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B0D6A101CC6D; Wed, 16 Nov 2022 13:41:45 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.24]) by smtp.corp.redhat.com (Postfix) with ESMTP id 723EE140EBF3; Wed, 16 Nov 2022 13:41:44 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <2b595b62f6ecd28298a860fcdc5b4941dcafd9eb.camel@kernel.org> References: <2b595b62f6ecd28298a860fcdc5b4941dcafd9eb.camel@kernel.org> <20221116104502.107431-1-jefflexu@linux.alibaba.com> <20221116104502.107431-2-jefflexu@linux.alibaba.com> To: Jeff Layton Cc: dhowells@redhat.com, Jingbo Xu , xiang@kernel.org, chao@kernel.org, linux-erofs@lists.ozlabs.org, linux-cachefs@redhat.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v3 1/2] fscache,cachefiles: add prepare_ondemand_read() callback MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2968418.1668606101.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Wed, 16 Nov 2022 13:41:41 +0000 Message-ID: <2968419.1668606101@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jeff Layton wrote: > > +static enum netfs_io_source cachefiles_do_prepare_read(struct netfs_c= ache_resources *cres, > > + loff_t *_start, size_t *_len, > > + unsigned long *_flags, loff_t i_size) > > _start is never changed, so it should be passed by value instead of by > pointer. Hmmm. The intention was that the start pointer should be able to be moved backwards by the cache - but that's not necessary in ->prepare_read() and ->expand_readahead() is provided for that now. So yes, the start pointer shouldn't get changed at this point. > I'd also reverse the position of the arguments for _flags and i_size. > Otherwise, the CPU/compiler have to shuffle things around more in > cachefiles_prepare_ondemand_read before they call this. Better to pass the flags in and then ignore them. That way it can tail ca= ll, or just call cachefiles_do_prepare_read() directly from erofs. If you're going to have a wrapper, then you might be just as well create a netfs_io_subrequest struct on the stack. David