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=-11.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 45BCBC433E7 for ; Thu, 8 Oct 2020 09:03:27 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 66B13215A4 for ; Thu, 8 Oct 2020 09:03:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 66B13215A4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 61B4B900002; Thu, 8 Oct 2020 05:03:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5CC8F6B005D; Thu, 8 Oct 2020 05:03:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4BAC6900002; Thu, 8 Oct 2020 05:03:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0027.hostedemail.com [216.40.44.27]) by kanga.kvack.org (Postfix) with ESMTP id 1F5036B005C for ; Thu, 8 Oct 2020 05:03:25 -0400 (EDT) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id A33FC1E14 for ; Thu, 8 Oct 2020 09:03:24 +0000 (UTC) X-FDA: 77348169528.26.nose60_2d0e6e2271d6 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin26.hostedemail.com (Postfix) with ESMTP id 980A318022DC0 for ; Thu, 8 Oct 2020 09:01:39 +0000 (UTC) X-HE-Tag: nose60_2d0e6e2271d6 X-Filterd-Recvd-Size: 6003 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf39.hostedemail.com (Postfix) with ESMTP for ; Thu, 8 Oct 2020 09:01:37 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 3232EAC3C; Thu, 8 Oct 2020 09:01:36 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id BD5DA1E1305; Thu, 8 Oct 2020 11:01:35 +0200 (CEST) Date: Thu, 8 Oct 2020 11:01:35 +0200 From: Jan Kara To: Ralph Campbell Cc: linux-mm@kvack.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, Dan Williams , Matthew Wilcox , Jan Kara , Alexander Viro , Theodore Ts'o , Christoph Hellwig , Andreas Dilger , "Darrick J. Wong" , Andrew Morton Subject: Re: [PATCH v2] ext4/xfs: add page refcount helper Message-ID: <20201008090135.GA3486@quack2.suse.cz> References: <20201007214925.11181-1-rcampbell@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201007214925.11181-1-rcampbell@nvidia.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed 07-10-20 14:49:25, Ralph Campbell wrote: > There are several places where ZONE_DEVICE struct pages assume a reference > count == 1 means the page is idle and free. Instead of open coding this, > add helper functions to hide this detail. > > Signed-off-by: Ralph Campbell > Reviewed-by: Christoph Hellwig > Acked-by: Darrick J. Wong > Acked-by: Theodore Ts'o # for fs/ext4/inode.c The patch looks good to me. Feel free to add: Reviewed-by: Jan Kara Honza > --- > > Changes in v2: > I strongly resisted the idea of extending this patch but after Jan > Kara's comment about there being more places that could be cleaned > up, I felt compelled to make this one tensy wensy change to add > a dax_wakeup_page() to match the dax_wait_page(). > I kept the Reviewed/Acked-bys since I don't think this substantially > changes the patch. > > fs/dax.c | 4 ++-- > fs/ext4/inode.c | 5 +---- > fs/xfs/xfs_file.c | 4 +--- > include/linux/dax.h | 15 +++++++++++++++ > mm/memremap.c | 3 ++- > 5 files changed, 21 insertions(+), 10 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index 5b47834f2e1b..85c63f735909 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -358,7 +358,7 @@ static void dax_disassociate_entry(void *entry, struct address_space *mapping, > for_each_mapped_pfn(entry, pfn) { > struct page *page = pfn_to_page(pfn); > > - WARN_ON_ONCE(trunc && page_ref_count(page) > 1); > + WARN_ON_ONCE(trunc && !dax_layout_is_idle_page(page)); > WARN_ON_ONCE(page->mapping && page->mapping != mapping); > page->mapping = NULL; > page->index = 0; > @@ -372,7 +372,7 @@ static struct page *dax_busy_page(void *entry) > for_each_mapped_pfn(entry, pfn) { > struct page *page = pfn_to_page(pfn); > > - if (page_ref_count(page) > 1) > + if (!dax_layout_is_idle_page(page)) > return page; > } > return NULL; > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 771ed8b1fadb..132620cbfa13 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -3937,10 +3937,7 @@ int ext4_break_layouts(struct inode *inode) > if (!page) > return 0; > > - error = ___wait_var_event(&page->_refcount, > - atomic_read(&page->_refcount) == 1, > - TASK_INTERRUPTIBLE, 0, 0, > - ext4_wait_dax_page(ei)); > + error = dax_wait_page(ei, page, ext4_wait_dax_page); > } while (error == 0); > > return error; > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index 3d1b95124744..a5304aaeaa3a 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -749,9 +749,7 @@ xfs_break_dax_layouts( > return 0; > > *retry = true; > - return ___wait_var_event(&page->_refcount, > - atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE, > - 0, 0, xfs_wait_dax_page(inode)); > + return dax_wait_page(inode, page, xfs_wait_dax_page); > } > > int > diff --git a/include/linux/dax.h b/include/linux/dax.h > index b52f084aa643..e2da78e87338 100644 > --- a/include/linux/dax.h > +++ b/include/linux/dax.h > @@ -243,6 +243,21 @@ static inline bool dax_mapping(struct address_space *mapping) > return mapping->host && IS_DAX(mapping->host); > } > > +static inline bool dax_layout_is_idle_page(struct page *page) > +{ > + return page_ref_count(page) == 1; > +} > + > +static inline void dax_wakeup_page(struct page *page) > +{ > + wake_up_var(&page->_refcount); > +} > + > +#define dax_wait_page(_inode, _page, _wait_cb) \ > + ___wait_var_event(&(_page)->_refcount, \ > + dax_layout_is_idle_page(_page), \ > + TASK_INTERRUPTIBLE, 0, 0, _wait_cb(_inode)) > + > #ifdef CONFIG_DEV_DAX_HMEM_DEVICES > void hmem_register_device(int target_nid, struct resource *r); > #else > diff --git a/mm/memremap.c b/mm/memremap.c > index 2bb276680837..504a10ff2edf 100644 > --- a/mm/memremap.c > +++ b/mm/memremap.c > @@ -12,6 +12,7 @@ > #include > #include > #include > +#include > > static DEFINE_XARRAY(pgmap_array); > > @@ -508,7 +509,7 @@ void free_devmap_managed_page(struct page *page) > { > /* notify page idle for dax */ > if (!is_device_private_page(page)) { > - wake_up_var(&page->_refcount); > + dax_wakeup_page(page); > return; > } > > -- > 2.20.1 > -- Jan Kara SUSE Labs, CR