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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 CDE21ECE588 for ; Tue, 15 Oct 2019 10:51:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A453A2089C for ; Tue, 15 Oct 2019 10:51:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571136662; bh=xd5Tg7VT8St3zf3d5FqDkcPBYWiTMCO/e69UVP9QSm8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=BdJfVM2vk2SdjOULBgGD7K5VkDPv9uAcxFdgd1Gx1zOLZ6CtQL0XWr+yPfhro1Biw os8g/EeRYHGNMsqAE4VArTsZ3AaNrGbDyck8T4+J3EgmI+qj+sJDb/oLF9IXQZTVxD YiSjPKj0ysIxJOykTFhxBpDvMV/A1KtBnrPfnx18= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731473AbfJOKvB (ORCPT ); Tue, 15 Oct 2019 06:51:01 -0400 Received: from mx2.suse.de ([195.135.220.15]:39318 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727142AbfJOKu7 (ORCPT ); Tue, 15 Oct 2019 06:50:59 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 19566B4B3; Tue, 15 Oct 2019 10:50:57 +0000 (UTC) Date: Tue, 15 Oct 2019 12:50:55 +0200 From: Michal Hocko To: Piotr Sarna Cc: linux-kernel@vger.kernel.org, mike.kravetz@oracle.com, linux-mm@kvack.org, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH] hugetlbfs: add O_TMPFILE support Message-ID: <20191015105055.GA24932@dhcp22.suse.cz> References: <22c29acf9c51dae17802e1b05c9e5e4051448c5c.1571129593.git.p.sarna@tlen.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <22c29acf9c51dae17802e1b05c9e5e4051448c5c.1571129593.git.p.sarna@tlen.pl> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 15-10-19 11:01:12, Piotr Sarna wrote: > With hugetlbfs, a common pattern for mapping anonymous huge pages > is to create a temporary file first. Really? I though that this is normally done by shmget(SHM_HUGETLB) or mmap(MAP_HUGETLB). Or maybe I misunderstood your definition on anonymous huge pages. > Currently libraries like > libhugetlbfs and seastar create these with a standard mkstemp+unlink > trick, but it would be more robust to be able to simply pass > the O_TMPFILE flag to open(). O_TMPFILE is already supported by several > file systems like ext4 and xfs. The implementation simply uses the existing > d_tmpfile utility function to instantiate the dcache entry for the file. > > Tested manually by successfully creating a temporary file by opening > it with (O_TMPFILE|O_RDWR) on mounted hugetlbfs and successfully > mapping 2M huge pages with it. Without the patch, trying to open > a file with O_TMPFILE results in -ENOSUP. > > Signed-off-by: Piotr Sarna > --- > fs/hugetlbfs/inode.c | 25 ++++++++++++++++++++++--- > 1 file changed, 22 insertions(+), 3 deletions(-) > > diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c > index 1dcc57189382..277b7d231db8 100644 > --- a/fs/hugetlbfs/inode.c > +++ b/fs/hugetlbfs/inode.c > @@ -815,8 +815,11 @@ static struct inode *hugetlbfs_get_inode(struct super_block *sb, > /* > * File creation. Allocate an inode, and we're done.. > */ > -static int hugetlbfs_mknod(struct inode *dir, > - struct dentry *dentry, umode_t mode, dev_t dev) > +static int do_hugetlbfs_mknod(struct inode *dir, > + struct dentry *dentry, > + umode_t mode, > + dev_t dev, > + bool tmpfile) > { > struct inode *inode; > int error = -ENOSPC; > @@ -824,13 +827,22 @@ static int hugetlbfs_mknod(struct inode *dir, > inode = hugetlbfs_get_inode(dir->i_sb, dir, mode, dev); > if (inode) { > dir->i_ctime = dir->i_mtime = current_time(dir); > - d_instantiate(dentry, inode); > + if (tmpfile) > + d_tmpfile(dentry, inode); > + else > + d_instantiate(dentry, inode); > dget(dentry); /* Extra count - pin the dentry in core */ > error = 0; > } > return error; > } > > +static int hugetlbfs_mknod(struct inode *dir, > + struct dentry *dentry, umode_t mode, dev_t dev) > +{ > + return do_hugetlbfs_mknod(dir, dentry, mode, dev, false); > +} > + > static int hugetlbfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) > { > int retval = hugetlbfs_mknod(dir, dentry, mode | S_IFDIR, 0); > @@ -844,6 +856,12 @@ static int hugetlbfs_create(struct inode *dir, struct dentry *dentry, umode_t mo > return hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0); > } > > +static int hugetlbfs_tmpfile(struct inode *dir, > + struct dentry *dentry, umode_t mode) > +{ > + return do_hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0, true); > +} > + > static int hugetlbfs_symlink(struct inode *dir, > struct dentry *dentry, const char *symname) > { > @@ -1102,6 +1120,7 @@ static const struct inode_operations hugetlbfs_dir_inode_operations = { > .mknod = hugetlbfs_mknod, > .rename = simple_rename, > .setattr = hugetlbfs_setattr, > + .tmpfile = hugetlbfs_tmpfile, > }; > > static const struct inode_operations hugetlbfs_inode_operations = { > -- > 2.21.0 > -- Michal Hocko SUSE Labs