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 4B003C7EE23 for ; Mon, 29 May 2023 15:38:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229966AbjE2PiC (ORCPT ); Mon, 29 May 2023 11:38:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36884 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229691AbjE2PiB (ORCPT ); Mon, 29 May 2023 11:38:01 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4F59DF3; Mon, 29 May 2023 08:37:56 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id A8E621F8B5; Mon, 29 May 2023 15:37:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1685374674; 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=VfC2IdpO+7uEiBHhtf+jBby1eH6FWQ5ChsH/O7pLur0=; b=gSf0t+vZ0B4myh9SviD61zCj1EH1uc1YlVGhNUgb/MCZXxzHgA8J3XifwVyza2KRq20hWr pZGc6AXCETQnP8jb+U91N20w7vIA7f5VobiHfL+/HbuvYR4sGOy/Qvb7o1ZnPBWqac7LBg kZfgvCRZqV9R20JgWvdDd1kIZir+lK0= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1685374674; 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=VfC2IdpO+7uEiBHhtf+jBby1eH6FWQ5ChsH/O7pLur0=; b=2+2tMQkyipmhcoqtqPAlHCSakWLZKRrkGMRW/G1J4HZuo+ZsFqLS2sYv/igpPh23T0GX71 4QMmBZeR6OW2F3DA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 87AAC13A36; Mon, 29 May 2023 15:37:54 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id BKs+INLGdGQrSAAAMHmgww (envelope-from ); Mon, 29 May 2023 15:37:54 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 0BA32A06F2; Mon, 29 May 2023 14:41:31 +0200 (CEST) Date: Mon, 29 May 2023 14:41:31 +0200 From: Jan Kara To: Christian Brauner Cc: Jan Kara , Al Viro , linux-fsdevel@vger.kernel.org, Miklos Szeredi , "Darrick J. Wong" , Ted Tso , Jaegeuk Kim , linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 4/6] fs: Establish locking order for unrelated directories Message-ID: <20230529124131.gbb3fmhrspl332i6@quack3> References: <20230525100654.15069-1-jack@suse.cz> <20230525101624.15814-4-jack@suse.cz> <20230526-polarstern-herrichten-32fc46c63bfc@brauner> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230526-polarstern-herrichten-32fc46c63bfc@brauner> Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Fri 26-05-23 11:45:15, Christian Brauner wrote: > On Thu, May 25, 2023 at 12:16:10PM +0200, Jan Kara wrote: > > Currently the locking order of inode locks for directories that are not > > in ancestor relationship is not defined because all operations that > > needed to lock two directories like this were serialized by > > sb->s_vfs_rename_mutex. However some filesystems need to lock two > > subdirectories for RENAME_EXCHANGE operations and for this we need the > > locking order established even for two tree-unrelated directories. > > Provide a helper function lock_two_inodes() that establishes lock > > ordering for any two inodes and use it in lock_two_directories(). > > > > CC: stable@vger.kernel.org > > Signed-off-by: Jan Kara > > --- > > fs/inode.c | 34 ++++++++++++++++++++++++++++++++++ > > fs/internal.h | 2 ++ > > fs/namei.c | 4 ++-- > > 3 files changed, 38 insertions(+), 2 deletions(-) > > > > diff --git a/fs/inode.c b/fs/inode.c > > index 577799b7855f..2015fa50d34a 100644 > > --- a/fs/inode.c > > +++ b/fs/inode.c > > @@ -1103,6 +1103,40 @@ void discard_new_inode(struct inode *inode) > > } > > EXPORT_SYMBOL(discard_new_inode); > > > > +/** > > + * lock_two_inodes - lock two inodes (may be regular files but also dirs) > > + * > > + * Lock any non-NULL argument. The caller must make sure that if he is passing > > + * in two directories, one is not ancestor of the other. Zero, one or two > > + * objects may be locked by this function. > > + * > > + * @inode1: first inode to lock > > + * @inode2: second inode to lock > > + * @subclass1: inode lock subclass for the first lock obtained > > + * @subclass2: inode lock subclass for the second lock obtained > > + */ > > +void lock_two_inodes(struct inode *inode1, struct inode *inode2, > > + unsigned subclass1, unsigned subclass2) > > +{ > > + if (!inode1 || !inode2) > > + goto lock; > > Before this change in > > lock_two_nondirectories(struct inode *inode1, struct inode *inode2) > > the swap() would cause the non-NULL inode to always be locked with > I_MUTEX_NONDIR2. Now it can be either I_MUTEX_NORMAL or I_MUTEX_NONDIR2. > Is that change intentional? Kind of. I don't think we really care so I didn't bother to complicate the code for this. If you think keeping the lockdep class consistent is worth it, I can modify the patch... Honza -- Jan Kara SUSE Labs, CR