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 X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B88C3C433E0 for ; Wed, 3 Mar 2021 09:28:15 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 03B1E64EDC for ; Wed, 3 Mar 2021 09:28:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 03B1E64EDC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 2BDC7100EB84F; Wed, 3 Mar 2021 01:28:14 -0800 (PST) Received-SPF: None (mailfrom) identity=mailfrom; client-ip=213.95.11.211; helo=verein.lst.de; envelope-from=hch@lst.de; receiver= Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 52C82100EBBB4 for ; Wed, 3 Mar 2021 01:28:11 -0800 (PST) Received: by verein.lst.de (Postfix, from userid 2407) id 9A87668BEB; Wed, 3 Mar 2021 10:28:08 +0100 (CET) Date: Wed, 3 Mar 2021 10:28:08 +0100 From: Christoph Hellwig To: Shiyang Ruan Subject: Re: [PATCH v2 02/10] fsdax: Factor helper: dax_fault_actor() Message-ID: <20210303092808.GC12784@lst.de> References: <20210226002030.653855-1-ruansy.fnst@fujitsu.com> <20210226002030.653855-3-ruansy.fnst@fujitsu.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210226002030.653855-3-ruansy.fnst@fujitsu.com> User-Agent: Mutt/1.5.17 (2007-11-01) Message-ID-Hash: SFW3YK3XSIEMP2OL3XWDNEJCVDGZJTKF X-Message-ID-Hash: SFW3YK3XSIEMP2OL3XWDNEJCVDGZJTKF X-MailFrom: hch@lst.de X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, darrick.wong@oracle.com, willy@infradead.org, jack@suse.cz, viro@zeniv.linux.org.uk, linux-btrfs@vger.kernel.org, ocfs2-devel@oss.oracle.com, david@fromorbit.com, hch@lst.de, rgoldwyn@suse.de X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Fri, Feb 26, 2021 at 08:20:22AM +0800, Shiyang Ruan wrote: > The core logic in the two dax page fault functions is similar. So, move > the logic into a common helper function. Also, to facilitate the > addition of new features, such as CoW, switch-case is no longer used to > handle different iomap types. > > Signed-off-by: Shiyang Ruan > --- > fs/dax.c | 211 ++++++++++++++++++++++++++++++------------------------- > 1 file changed, 117 insertions(+), 94 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index 7031e4302b13..9dea1572868e 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -1289,6 +1289,93 @@ static int dax_fault_cow_page(struct vm_fault *vmf, struct iomap *iomap, > return 0; > } > > +static vm_fault_t dax_fault_insert_pfn(struct vm_fault *vmf, pfn_t pfn, > + bool pmd, bool write) > +{ > + vm_fault_t ret; > + > + if (!pmd) { > + struct vm_area_struct *vma = vmf->vma; > + unsigned long address = vmf->address; > + > + if (write) > + ret = vmf_insert_mixed_mkwrite(vma, address, pfn); > + else > + ret = vmf_insert_mixed(vma, address, pfn); > + } else > + ret = vmf_insert_pfn_pmd(vmf, pfn, write); What about simplifying this a little bit more, something like: if (pmd) return vmf_insert_pfn_pmd(vmf, pfn, write); if (write) return vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn); return vmf_insert_mixed(vmf->vma, vmf->address, pfn); also given that this only has a single user, why not keep open coding it in the caller? > +#ifdef CONFIG_FS_DAX_PMD > +static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, > + struct iomap *iomap, void **entry); > +#else > +static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, > + struct iomap *iomap, void **entry) > +{ > + return VM_FAULT_FALLBACK; > +} > +#endif Can we try to avoid the forward declaration? Also is there a reason dax_pmd_load_hole does not compile for the !CONFIG_FS_DAX_PMD case? If it compiles fine we can just rely on IS_ENABLED() based dead code elimination entirely. > + /* if we are reading UNWRITTEN and HOLE, return a hole. */ > + if (!write && > + (iomap->type == IOMAP_UNWRITTEN || iomap->type == IOMAP_HOLE)) { > + if (!pmd) > + return dax_load_hole(xas, mapping, &entry, vmf); > + else > + return dax_pmd_load_hole(xas, vmf, iomap, &entry); > + } > + > + if (iomap->type != IOMAP_MAPPED) { > + WARN_ON_ONCE(1); > + return VM_FAULT_SIGBUS; > + } Nit: I'd use a switch statement here for a clarity: switch (iomap->type) { case IOMAP_MAPPED: break; case IOMAP_UNWRITTEN: case IOMAP_HOLE: if (!write) { if (!pmd) return dax_load_hole(xas, mapping, &entry, vmf); return dax_pmd_load_hole(xas, vmf, iomap, &entry); } break; default: WARN_ON_ONCE(1); return VM_FAULT_SIGBUS; } > + err = dax_iomap_pfn(iomap, pos, size, &pfn); > + if (err) > + goto error_fault; > + > + entry = dax_insert_entry(xas, mapping, vmf, entry, pfn, 0, > + write && !sync); > + > + if (sync) > + return dax_fault_synchronous_pfnp(pfnp, pfn); > + > + ret = dax_fault_insert_pfn(vmf, pfn, pmd, write); > + > +error_fault: > + if (err) > + ret = dax_fault_return(err); > + > + return ret; It seems like the only place that sets err is the dax_iomap_pfn case above. So I'd move the dax_fault_return there, which then allows a direct return for everyone else, including the open coded version of dax_fault_insert_pfn. I really like where this is going! _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org