From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f180.google.com ([209.85.212.180]:38401 "EHLO mail-wi0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753272AbbI3TYF (ORCPT ); Wed, 30 Sep 2015 15:24:05 -0400 Received: by wiclk2 with SMTP id lk2so76747567wic.1 for ; Wed, 30 Sep 2015 12:24:03 -0700 (PDT) From: Robin Ruede To: linux-btrfs@vger.kernel.org Cc: Robin Ruede Subject: [PATCH] btrfs: fix resending received snapshot with parent Date: Wed, 30 Sep 2015 21:23:33 +0200 Message-Id: <1443641013-26765-1-git-send-email-rruede+git@gmail.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: This fixes a regression introduced by 37b8d27d between v4.1 and v4.2. When a snapshot is received, its received_uuid is set to the original uuid of the subvolume. When that snapshot is then resent to a third filesystem, it's received_uuid is set to the second uuid instead of the original one. The same was true for the parent_uuid. This behaviour was partially changed in 37b8d27d, but in that patch only the parent_uuid was taken from the real original, not the uuid itself, causing the search for the parent to fail in the case below. This happens for example when trying to send a series of linked snapshots (e.g. created by snapper) from the backup file system back to the original one. The following commands reproduce the issue in v4.2.1 (no error in 4.1.6) # setup three test file systems for i in 1 2 3; do truncate -s 50M fs$i mkfs.btrfs fs$i mkdir $i mount fs$i $i done echo "content" > 1/testfile btrfs su snapshot -r 1/ 1/snap1 echo "changed content" > 1/testfile btrfs su snapshot -r 1/ 1/snap2 # works fine: btrfs send 1/snap1 | btrfs receive 2/ btrfs send -p 1/snap1 1/snap2 | btrfs receive 2/ # ERROR: could not find parent subvolume btrfs send 2/snap1 | btrfs receive 3/ btrfs send -p 2/snap1 2/snap2 | btrfs receive 3/ Signed-off-by: Robin Ruede --- fs/btrfs/send.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index aa72bfd..890933b 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -2351,8 +2351,14 @@ static int send_subvol_begin(struct send_ctx *sctx) } TLV_PUT_STRING(sctx, BTRFS_SEND_A_PATH, name, namelen); - TLV_PUT_UUID(sctx, BTRFS_SEND_A_UUID, - sctx->send_root->root_item.uuid); + + if (!btrfs_is_empty_uuid(sctx->send_root->root_item.received_uuid)) + TLV_PUT_UUID(sctx, BTRFS_SEND_A_UUID, + sctx->send_root->root_item.received_uuid); + else + TLV_PUT_UUID(sctx, BTRFS_SEND_A_UUID, + sctx->send_root->root_item.uuid); + TLV_PUT_U64(sctx, BTRFS_SEND_A_CTRANSID, le64_to_cpu(sctx->send_root->root_item.ctransid)); if (parent_root) { -- 2.6.0