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=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 557DFC4361B for ; Mon, 14 Dec 2020 21:40:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 16D22221FC for ; Mon, 14 Dec 2020 21:40:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387737AbgLNVkP (ORCPT ); Mon, 14 Dec 2020 16:40:15 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:48823 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387514AbgLNVkP (ORCPT ); Mon, 14 Dec 2020 16:40:15 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607981929; h=from:from:reply-to:subject:subject: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=WR+RyLQ7QZDrTrU3w6RGuPv+flEY6ZP3IN3AdHw7u8o=; b=YaPRy5fqKBMUg68Uko3ChKxHWJA5DYaqGDr2XBeZRKA5ovMNIy0DdoCdq9qk1DTEoYsM5k nNo/vFBl0PYOpBxFtoW8BBC0GwQ9obhzY3mo3eOhL9JQ/KJ/69YkIYIQLyMQfWdIm9a+zu QwOUsGXvOMjHIPDZUhAZ0DzANc+jhb8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-256-EgKEIIDfNkOxTyBCXwdYlQ-1; Mon, 14 Dec 2020 16:38:46 -0500 X-MC-Unique: EgKEIIDfNkOxTyBCXwdYlQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 456C16D531; Mon, 14 Dec 2020 21:38:45 +0000 (UTC) Received: from horse.redhat.com (ovpn-114-168.rdu2.redhat.com [10.10.114.168]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5A3D718A9E; Mon, 14 Dec 2020 21:38:44 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id E0784220BCF; Mon, 14 Dec 2020 16:38:43 -0500 (EST) Date: Mon, 14 Dec 2020 16:38:43 -0500 From: Vivek Goyal To: Jeff Layton Cc: Amir Goldstein , Sargun Dhillon , Miklos Szeredi , overlayfs , Linux FS-devel Mailing List , Matthew Wilcox , NeilBrown , Jan Kara Subject: Re: [RFC PATCH 2/2] overlayfs: propagate errors from upper to overlay sb in sync_fs Message-ID: <20201214213843.GA3453@redhat.com> References: <20201213132713.66864-1-jlayton@kernel.org> <20201213132713.66864-3-jlayton@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201213132713.66864-3-jlayton@kernel.org> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org On Sun, Dec 13, 2020 at 08:27:13AM -0500, Jeff Layton wrote: > Peek at the upper layer's errseq_t at mount time for volatile mounts, > and record it in the per-sb info. In sync_fs, check for an error since > the recorded point and set it in the overlayfs superblock if there was > one. > > Signed-off-by: Jeff Layton > --- While we are solving problem for non-volatile overlay mount, I also started thinking, what about non-volatile overlay syncfs() writeback errors. Looks like these will not be reported to user space at all as of now (because we never update overlay_sb->s_wb_err ever). A patch like this might fix it. (compile tested only). overlayfs: Report syncfs() errors to user space Currently, syncfs(), calls filesystem ->sync_fs() method but ignores the return code. But certain writeback errors can still be reported on syncfs() by checking errors on super block. ret2 = errseq_check_and_advance(&sb->s_wb_err, &f.file->f_sb_err); For the case of overlayfs, we never set overlayfs super block s_wb_err. That means sync() will never report writeback errors on overlayfs uppon syncfs(). Fix this by updating overlay sb->sb_wb_err upon ->sync_fs() call. And that should mean that user space syncfs() call should see writeback errors. ovl_fsync() does not need anything special because if there are writeback errors underlying filesystem will report it through vfs_fsync_range() return code and user space will see it. Signed-off-by: Vivek Goyal --- fs/overlayfs/ovl_entry.h | 1 + fs/overlayfs/super.c | 14 +++++++++++--- 2 files changed, 12 insertions(+), 3 deletions(-) Index: redhat-linux/fs/overlayfs/super.c =================================================================== --- redhat-linux.orig/fs/overlayfs/super.c 2020-12-14 15:33:43.934400880 -0500 +++ redhat-linux/fs/overlayfs/super.c 2020-12-14 16:15:07.127400880 -0500 @@ -259,7 +259,7 @@ static int ovl_sync_fs(struct super_bloc { struct ovl_fs *ofs = sb->s_fs_info; struct super_block *upper_sb; - int ret; + int ret, ret2; if (!ovl_upper_mnt(ofs)) return 0; @@ -283,7 +283,14 @@ static int ovl_sync_fs(struct super_bloc ret = sync_filesystem(upper_sb); up_read(&upper_sb->s_umount); - return ret; + if (errseq_check(&upper_sb->s_wb_err, sb->s_wb_err)) { + /* Upper sb has errors since last time */ + spin_lock(&ofs->errseq_lock); + ret2 = errseq_check_and_advance(&upper_sb->s_wb_err, + &sb->s_wb_err); + spin_unlock(&ofs->errseq_lock); + } + return ret ? ret : ret2; } /** @@ -1873,6 +1880,7 @@ static int ovl_fill_super(struct super_b if (!cred) goto out_err; + spin_lock_init(&ofs->errseq_lock); /* Is there a reason anyone would want not to share whiteouts? */ ofs->share_whiteout = true; @@ -1945,7 +1953,7 @@ static int ovl_fill_super(struct super_b sb->s_stack_depth = ovl_upper_mnt(ofs)->mnt_sb->s_stack_depth; sb->s_time_gran = ovl_upper_mnt(ofs)->mnt_sb->s_time_gran; - + sb->s_wb_err = errseq_sample(&ovl_upper_mnt(ofs)->mnt_sb->s_wb_err); } oe = ovl_get_lowerstack(sb, splitlower, numlower, ofs, layers); err = PTR_ERR(oe); Index: redhat-linux/fs/overlayfs/ovl_entry.h =================================================================== --- redhat-linux.orig/fs/overlayfs/ovl_entry.h 2020-12-14 15:33:43.934400880 -0500 +++ redhat-linux/fs/overlayfs/ovl_entry.h 2020-12-14 15:34:13.509400880 -0500 @@ -79,6 +79,7 @@ struct ovl_fs { atomic_long_t last_ino; /* Whiteout dentry cache */ struct dentry *whiteout; + spinlock_t errseq_lock; }; static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs)