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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9B8AC433EF for ; Fri, 26 Nov 2021 09:22:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1376288AbhKZJZi (ORCPT ); Fri, 26 Nov 2021 04:25:38 -0500 Received: from smtp-out2.suse.de ([195.135.220.29]:39006 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233778AbhKZJXh (ORCPT ); Fri, 26 Nov 2021 04:23:37 -0500 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 47D431FDFD; Fri, 26 Nov 2021 09:20:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1637918424; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=/usd3bihFH8h8Sl+Gav3FHfBHtdDk46haHDYjEnfXUc=; b=rtKQo6sqahD+RKAzi8qgj1rUY86w3JG/TuFQOIwrCRd8Bs3NUzfVDR+9Kqh/GaBKIDxxZS k76DCWEJspNVg7uDgmocE3n7mO0Uz+oY0DjzKpy3DWea4xDDINl47hajN6tST0Cl0o22ST is7tgsJB0/F+S8LH4NINVvxJ6joBI0I= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1637918424; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=/usd3bihFH8h8Sl+Gav3FHfBHtdDk46haHDYjEnfXUc=; b=HlZckQEdqAg2aTzynhoSC5RxuGZR3ku1ReLoi01tjJxJwlTs5mBO3nK1r3nF/9L5VBjzf/ EUd2QQn0qJUr5uAQ== Received: from quack2.suse.cz (unknown [10.100.200.198]) by relay2.suse.de (Postfix) with ESMTP id 097EAA3B81; Fri, 26 Nov 2021 09:20:24 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id E733D1E11F3; Fri, 26 Nov 2021 10:20:23 +0100 (CET) Date: Fri, 26 Nov 2021 10:20:23 +0100 From: Jan Kara To: Chengguang Xu Cc: miklos@szeredi.hu, jack@suse.cz, amir73il@gmail.com, linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Chengguang Xu Subject: Re: [RFC PATCH V6 4/7] ovl: set 'DONTCACHE' flag for overlayfs inode Message-ID: <20211126092023.GD13004@quack2.suse.cz> References: <20211122030038.1938875-1-cgxu519@mykernel.net> <20211122030038.1938875-5-cgxu519@mykernel.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211122030038.1938875-5-cgxu519@mykernel.net> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org On Mon 22-11-21 11:00:35, Chengguang Xu wrote: > From: Chengguang Xu > > Set 'DONTCACHE' flag to overlayfs inode so that > upper inode to be always synced before eviction. > > Signed-off-by: Chengguang Xu > --- > fs/overlayfs/inode.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c > index 027ffc0a2539..c4472299d5df 100644 > --- a/fs/overlayfs/inode.c > +++ b/fs/overlayfs/inode.c > @@ -791,6 +791,7 @@ void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip, > ovl_copyattr(realinode, inode); > ovl_copyflags(realinode, inode); > ovl_map_ino(inode, ino, fsid); > + d_mark_dontcache(inode); > } Doesn't this effectively disable dcache for overlayfs dentries? I mean e.g. whenever overlayfs file is closed, we will drop its dentry & inode from the cache. Upper and lower inodes / dentries stay in cache so no disk access should be needed to reconstruct overlayfs dentry & inode but still it may be a bit costly? I guess others more familiar with overlayfs have to judge. Honza -- Jan Kara SUSE Labs, CR