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=-20.2 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, USER_AGENT_GIT 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 39018C07E9B for ; Mon, 19 Jul 2021 15:47:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 219D160FD7 for ; Mon, 19 Jul 2021 15:47:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344840AbhGSPG4 (ORCPT ); Mon, 19 Jul 2021 11:06:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:40444 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344347AbhGSOsq (ORCPT ); Mon, 19 Jul 2021 10:48:46 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A74C261413; Mon, 19 Jul 2021 15:28:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626708499; bh=Y2flYOWkVKABzaJTH40ptU3lDI5mulmmseakB1EH4pI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uX541LvbLEThJd9b1SzKKj1UV5JujAQmDmT1TwIOVjtf1//VRb8T3/LIl6pI0grrn IM1lC1V//bdB7nYu6RO0zloyOZ7x/nehp2xzTr4JeJhqybjX47CMEywCZ5ZcuTayu3 pApXRfSsJzN9p6KODPcOb2xaiwJoW5NH9KnPo2S8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Filipe Manana , David Sterba Subject: [PATCH 4.19 017/421] btrfs: send: fix invalid path for unlink operations after parent orphanization Date: Mon, 19 Jul 2021 16:47:08 +0200 Message-Id: <20210719144946.874784051@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210719144946.310399455@linuxfoundation.org> References: <20210719144946.310399455@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Filipe Manana commit d8ac76cdd1755b21e8c008c28d0b7251c0b14986 upstream. During an incremental send operation, when processing the new references for the current inode, we might send an unlink operation for another inode that has a conflicting path and has more than one hard link. However this path was computed and cached before we processed previous new references for the current inode. We may have orphanized a directory of that path while processing a previous new reference, in which case the path will be invalid and cause the receiver process to fail. The following reproducer triggers the problem and explains how/why it happens in its comments: $ cat test-send-unlink.sh #!/bin/bash DEV=/dev/sdi MNT=/mnt/sdi mkfs.btrfs -f $DEV >/dev/null mount $DEV $MNT # Create our test files and directory. Inode 259 (file3) has two hard # links. touch $MNT/file1 touch $MNT/file2 touch $MNT/file3 mkdir $MNT/A ln $MNT/file3 $MNT/A/hard_link # Filesystem looks like: # # . (ino 256) # |----- file1 (ino 257) # |----- file2 (ino 258) # |----- file3 (ino 259) # |----- A/ (ino 260) # |---- hard_link (ino 259) # # Now create the base snapshot, which is going to be the parent snapshot # for a later incremental send. btrfs subvolume snapshot -r $MNT $MNT/snap1 btrfs send -f /tmp/snap1.send $MNT/snap1 # Move inode 257 into directory inode 260. This results in computing the # path for inode 260 as "/A" and caching it. mv $MNT/file1 $MNT/A/file1 # Move inode 258 (file2) into directory inode 260, with a name of # "hard_link", moving first inode 259 away since it currently has that # location and name. mv $MNT/A/hard_link $MNT/tmp mv $MNT/file2 $MNT/A/hard_link # Now rename inode 260 to something else (B for example) and then create # a hard link for inode 258 that has the old name and location of inode # 260 ("/A"). mv $MNT/A $MNT/B ln $MNT/B/hard_link $MNT/A # Filesystem now looks like: # # . (ino 256) # |----- tmp (ino 259) # |----- file3 (ino 259) # |----- B/ (ino 260) # | |---- file1 (ino 257) # | |---- hard_link (ino 258) # | # |----- A (ino 258) # Create another snapshot of our subvolume and use it for an incremental # send. btrfs subvolume snapshot -r $MNT $MNT/snap2 btrfs send -f /tmp/snap2.send -p $MNT/snap1 $MNT/snap2 # Now unmount the filesystem, create a new one, mount it and try to # apply both send streams to recreate both snapshots. umount $DEV mkfs.btrfs -f $DEV >/dev/null mount $DEV $MNT # First add the first snapshot to the new filesystem by applying the # first send stream. btrfs receive -f /tmp/snap1.send $MNT # The incremental receive operation below used to fail with the # following error: # # ERROR: unlink A/hard_link failed: No such file or directory # # This is because when send is processing inode 257, it generates the # path for inode 260 as "/A", since that inode is its parent in the send # snapshot, and caches that path. # # Later when processing inode 258, it first processes its new reference # that has the path of "/A", which results in orphanizing inode 260 # because there is a a path collision. This results in issuing a rename # operation from "/A" to "/o260-6-0". # # Finally when processing the new reference "B/hard_link" for inode 258, # it notices that it collides with inode 259 (not yet processed, because # it has a higher inode number), since that inode has the name # "hard_link" under the directory inode 260. It also checks that inode # 259 has two hardlinks, so it decides to issue a unlink operation for # the name "hard_link" for inode 259. However the path passed to the # unlink operation is "/A/hard_link", which is incorrect since currently # "/A" does not exists, due to the orphanization of inode 260 mentioned # before. The path is incorrect because it was computed and cached # before the orphanization. This results in the receiver to fail with # the above error. btrfs receive -f /tmp/snap2.send $MNT umount $MNT When running the test, it fails like this: $ ./test-send-unlink.sh Create a readonly snapshot of '/mnt/sdi' in '/mnt/sdi/snap1' At subvol /mnt/sdi/snap1 Create a readonly snapshot of '/mnt/sdi' in '/mnt/sdi/snap2' At subvol /mnt/sdi/snap2 At subvol snap1 At snapshot snap2 ERROR: unlink A/hard_link failed: No such file or directory Fix this by recomputing a path before issuing an unlink operation when processing the new references for the current inode if we previously have orphanized a directory. A test case for fstests will follow soon. CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Filipe Manana Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/send.c | 11 +++++++++++ 1 file changed, 11 insertions(+) --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -4081,6 +4081,17 @@ static int process_recorded_refs(struct if (ret < 0) goto out; } else { + /* + * If we previously orphanized a directory that + * collided with a new reference that we already + * processed, recompute the current path because + * that directory may be part of the path. + */ + if (orphanized_dir) { + ret = refresh_ref_path(sctx, cur); + if (ret < 0) + goto out; + } ret = send_unlink(sctx, cur->full_path); if (ret < 0) goto out;