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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 2C870C2BA19 for ; Tue, 14 Apr 2020 15:45:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0EB6820767 for ; Tue, 14 Apr 2020 15:45:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2440854AbgDNPpH (ORCPT ); Tue, 14 Apr 2020 11:45:07 -0400 Received: from mga12.intel.com ([192.55.52.136]:40843 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2440812AbgDNPpE (ORCPT ); Tue, 14 Apr 2020 11:45:04 -0400 IronPort-SDR: QtunTgQ6lzJWG6poeTBxJsSNF1lDilE/txO1AWkwswSGvn577/5YpsW0a1uvWoW/eC767pz7GH Az1eXDCv+Qbg== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Apr 2020 08:45:02 -0700 IronPort-SDR: hWs3uwLatEhjJd86Tkgb0DG3KjHO8EiVpBpI1389CdNYZ1ahFx2g1A5PeXI+W7DudRTWrql2Zl PTSG0PQ6wTAg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,382,1580803200"; d="scan'208";a="242030231" Received: from iweiny-desk2.sc.intel.com ([10.3.52.147]) by orsmga007.jf.intel.com with ESMTP; 14 Apr 2020 08:45:02 -0700 Date: Tue, 14 Apr 2020 08:45:01 -0700 From: Ira Weiny To: Jan Kara Cc: linux-kernel@vger.kernel.org, "Darrick J. Wong" , Dan Williams , Dave Chinner , Christoph Hellwig , "Theodore Y. Ts'o" , Jeff Moyer , linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH V7 7/9] fs: Define I_DONTCACNE in VFS layer Message-ID: <20200414154501.GH1649878@iweiny-DESK2.sc.intel.com> References: <20200413054046.1560106-1-ira.weiny@intel.com> <20200413054046.1560106-8-ira.weiny@intel.com> <20200414152630.GE28226@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200414152630.GE28226@quack2.suse.cz> User-Agent: Mutt/1.11.1 (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 14, 2020 at 05:26:30PM +0200, Jan Kara wrote: > On Sun 12-04-20 22:40:44, ira.weiny@intel.com wrote: > > From: Ira Weiny > > > > DAX effective mode changes (setting of S_DAX) require inode eviction. > > > > Define a flag which can be set to inform the VFS layer that inodes > > should not be cached. This will expedite the eviction of those nodes > > requiring reload. > > > > Signed-off-by: Ira Weiny > > This inode flag will have a limited impact because usually dentry will > still hold inode reference. So until dentry is evicted, inode stays as > well. Agreed but at least this keeps the inode from being cached until that time. FWIW the ext4 patches seem to have a much longer delay when issuing drop_caches and I'm not 100% sure why. I've sent out those patches RFC to get the discussions started. I feel like I have missed something there but it does eventually flip the S_DAX flag. > So I think we'd need something like DCACHE_DONTCACHE flag as well to > discard a dentry whenever dentry usecount hits zero (which will be > generally on last file close). What do you think? I wanted to do something like this but I was not sure how to trigger the DCACHE_DONTCACHE on the correct 'parent' dentry. Can't their be multiple dentries pointing to the same inode? In which case, would you need to flag them all? Ira > > And I'd note that checking for I_DONTCACHE flag in dput() isn't > straightforward because of locking so that's why I suggest separate dentry > flag. > > Honza > > > --- > > include/linux/fs.h | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > diff --git a/include/linux/fs.h b/include/linux/fs.h > > index a818ced22961..e2db71d150c3 100644 > > --- a/include/linux/fs.h > > +++ b/include/linux/fs.h > > @@ -2151,6 +2151,8 @@ static inline void kiocb_clone(struct kiocb *kiocb, struct kiocb *kiocb_src, > > * > > * I_CREATING New object's inode in the middle of setting up. > > * > > + * I_DONTCACHE Do not cache the inode > > + * > > * Q: What is the difference between I_WILL_FREE and I_FREEING? > > */ > > #define I_DIRTY_SYNC (1 << 0) > > @@ -2173,6 +2175,7 @@ static inline void kiocb_clone(struct kiocb *kiocb, struct kiocb *kiocb_src, > > #define I_WB_SWITCH (1 << 13) > > #define I_OVL_INUSE (1 << 14) > > #define I_CREATING (1 << 15) > > +#define I_DONTCACHE (1 << 16) > > > > #define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC) > > #define I_DIRTY (I_DIRTY_INODE | I_DIRTY_PAGES) > > @@ -3042,7 +3045,8 @@ extern int inode_needs_sync(struct inode *inode); > > extern int generic_delete_inode(struct inode *inode); > > static inline int generic_drop_inode(struct inode *inode) > > { > > - return !inode->i_nlink || inode_unhashed(inode); > > + return !inode->i_nlink || inode_unhashed(inode) || > > + (inode->i_state & I_DONTCACHE); > > } > > > > extern struct inode *ilookup5_nowait(struct super_block *sb, > > -- > > 2.25.1 > > > -- > Jan Kara > SUSE Labs, CR