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=-10.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,URIBL_BLOCKED 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 ACF7FC47095 for ; Wed, 7 Oct 2020 15:36:48 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E817D2173E for ; Wed, 7 Oct 2020 15:36:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="A3gBZ56H" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E817D2173E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CB8036B005C; Wed, 7 Oct 2020 11:36:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C68466B0062; Wed, 7 Oct 2020 11:36:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B2F8A6B0068; Wed, 7 Oct 2020 11:36:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 8710F6B005C for ; Wed, 7 Oct 2020 11:36:46 -0400 (EDT) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id BD5FC3622 for ; Wed, 7 Oct 2020 15:36:45 +0000 (UTC) X-FDA: 77345531970.21.bat44_510f19a271d0 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin21.hostedemail.com (Postfix) with ESMTP id 90715180442C0 for ; Wed, 7 Oct 2020 15:36:45 +0000 (UTC) X-HE-Tag: bat44_510f19a271d0 X-Filterd-Recvd-Size: 7598 Received: from userp2120.oracle.com (userp2120.oracle.com [156.151.31.85]) by imf22.hostedemail.com (Postfix) with ESMTP for ; Wed, 7 Oct 2020 15:36:44 +0000 (UTC) Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 097FXS7M021665; Wed, 7 Oct 2020 15:36:33 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2020-01-29; bh=5f69miCPt+NV0LANFf/qO1h0nLQY1MwO9sbrOzCAKXg=; b=A3gBZ56H1novabUez4R1w5Sej3V87adyElfnlhPv4YAW+IMki1gknRxoArFhu/hvDAJ2 n1iqburVQ+/f8wX66ajrL4xQ+XBLT2th0ZLHzcMkyNkctAiQYjLhg6NR+JtetIa4wi8y DG7mbgV27hqknqaHdLnJhXgbgHW2RFG7Rr+nNTHF+qyKSqrBifdQG93TtWcDWvmLwItt ZbkcHPG/TSkVlxOLuSP6QiKqBXKJ7Up45WwlayF9lRAhMconbPSSumdcdHLcelw/HHLM wMQIUfDyJRB0zB+In2+AQKQ0jx8FIwGI1oC9V8IFwuQV3M8t7EIYBExw42D2Ro6uECeP JQ== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2120.oracle.com with ESMTP id 33xhxn2f9h-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 07 Oct 2020 15:36:33 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 097FZIEx008693; Wed, 7 Oct 2020 15:36:32 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by userp3020.oracle.com with ESMTP id 33yyjhc1at-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 07 Oct 2020 15:36:32 +0000 Received: from abhmp0009.oracle.com (abhmp0009.oracle.com [141.146.116.15]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 097FaKhX018653; Wed, 7 Oct 2020 15:36:20 GMT Received: from localhost (/67.169.218.210) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 07 Oct 2020 08:36:20 -0700 Date: Wed, 7 Oct 2020 08:36:19 -0700 From: "Darrick J. Wong" 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 , Andrew Morton Subject: Re: [PATCH] ext4/xfs: add page refcount helper Message-ID: <20201007153619.GD49547@magnolia> References: <20201006230930.3908-1-rcampbell@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201006230930.3908-1-rcampbell@nvidia.com> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9767 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 adultscore=0 bulkscore=0 phishscore=0 mlxlogscore=999 mlxscore=0 spamscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2010070099 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9767 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 malwarescore=0 bulkscore=0 impostorscore=0 lowpriorityscore=0 suspectscore=0 phishscore=0 mlxlogscore=999 adultscore=0 clxscore=1011 spamscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2010070099 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 Tue, Oct 06, 2020 at 04:09:30PM -0700, 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 a helper function to hide this detail. > > Signed-off-by: Ralph Campbell > Reviewed-by: Christoph Hellwig > --- > > I'm resending this as a separate patch since I think it is ready to > merge. Originally, this was part of an RFC and is unchanged from v3: > https://lore.kernel.org/linux-mm/20201001181715.17416-1-rcampbell@nvidia.com > > It applies cleanly to linux-5.9.0-rc7-mm1 but doesn't really > depend on anything, just simple merge conflicts when applied to > other trees. > I'll let the various maintainers decide which tree and when to merge. > It isn't urgent since it is a clean up patch. > > fs/dax.c | 4 ++-- > fs/ext4/inode.c | 5 +---- > fs/xfs/xfs_file.c | 4 +--- > include/linux/dax.h | 10 ++++++++++ > 4 files changed, 14 insertions(+), 9 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); I don't mind this open-coded soup getting cleaned up into a macro, though my general opinion is that if the mm/dax developers are ok with this then: Acked-by: Darrick J. Wong --D > } > > int > diff --git a/include/linux/dax.h b/include/linux/dax.h > index b52f084aa643..8909a91cd381 100644 > --- a/include/linux/dax.h > +++ b/include/linux/dax.h > @@ -243,6 +243,16 @@ 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; > +} > + > +#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 > -- > 2.20.1 >