btrfs: test sending snapshots received from other filesystems

Test that sending a snapshot received from a different filesystem is
possible for both full and incremental send operations.

This used to work until the linux kernel release 4.2, but a commit [1] in
that release introduced a regression which did not allow this anymore.

The regression is fixed by the linux kernel patch titled:

  "btrfs: fix resending received snapshot with parent"

[1] 37b8d27de5d0 ("Btrfs: use received_uuid of parent during send")

Cc: Josef Bacik <jbacik@fb.com>
Cc: Robin Ruede <rruede+git@gmail.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/btrfs/111

@@ -0,0 +1,133 @@
+#! /bin/bash
+# FS QA Test No. btrfs/111
+#
+# Test that resending snapshots from a different filesystem is possible for
+# both full and incremental send operations.
+#
+#-----------------------------------------------------------------------
+# Copyright (C) 2015 SUSE Linux Products GmbH. All Rights Reserved.
+# Author: Filipe Manana <fdmanana@suse.com>
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#-----------------------------------------------------------------------
+#
+
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+tmp=/tmp/$$
+status=1	# failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	cd /
+	rm -fr $send_files_dir
+	rm -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# real QA test starts here
+_supported_fs btrfs
+_supported_os Linux
+_require_scratch
+_need_to_be_root
+
+send_files_dir=$TEST_DIR/btrfs-test-$seq
+
+rm -f $seqres.full
+rm -fr $send_files_dir
+mkdir $send_files_dir
+
+_scratch_mkfs >>$seqres.full 2>&1
+_scratch_mount
+
+# Create a test file
+$XFS_IO_PROG -f -c "pwrite -S 0xaa 0K 32K" $SCRATCH_MNT/foo | _filter_xfs_io
+
+# Create the first snapshot.
+_run_btrfs_util_prog subvolume snapshot -r $SCRATCH_MNT $SCRATCH_MNT/snap1
+
+# Modify our file and create the second snapshot, used later for an incremental
+# send operation.
+$XFS_IO_PROG -c "pwrite -S 0xbb 4K 4K" $SCRATCH_MNT/foo | _filter_xfs_io
+
+_run_btrfs_util_prog subvolume snapshot -r $SCRATCH_MNT $SCRATCH_MNT/snap2
+
+echo "File digests in the first filesystem:"
+md5sum $SCRATCH_MNT/snap1/foo | _filter_scratch
+md5sum $SCRATCH_MNT/snap2/foo | _filter_scratch
+
+# Save send streams for the snapshots. For the first one we use a full send
+# operation and the for the second snapshot we use an incremental send.
+_run_btrfs_util_prog send $SCRATCH_MNT/snap1 -f $send_files_dir/1.snap
+_run_btrfs_util_prog send -p $SCRATCH_MNT/snap1 $SCRATCH_MNT/snap2 \
+	-f $send_files_dir/2.snap
+
+# Create a new filesystem and receive the snapshots.
+_scratch_unmount
+_scratch_mkfs >>$seqres.full 2>&1
+_scratch_mount
+
+_run_btrfs_util_prog receive $SCRATCH_MNT -vv -f $send_files_dir/1.snap
+_run_btrfs_util_prog receive $SCRATCH_MNT -vv -f $send_files_dir/2.snap
+
+echo "File digests in the second filesystem:"
+# Must match the digests we got in the first filesystem.
+md5sum $SCRATCH_MNT/snap1/foo | _filter_scratch
+md5sum $SCRATCH_MNT/snap2/foo | _filter_scratch
+
+# Call sync to flush all delalloc data that the receiver processes created.
+# Although 'btrfs receive' at the end calls a btrfs specific ioctl to change
+# the snapshot from RW mode to RO mode, which commits the current btrfs
+# transaction, the dealalloc data is not flushed, as the transaction commit
+# intentionally does not do it unless the fs is mounted with '-o flushoncommit'.
+# This is a detail that should probably be addressed either in the btrfs ioctls
+# called by 'btrfs receive' or in the tools - our test has a different purpose,
+# so we get around this by calling 'sync' to make sure all delalloc data is
+# durably persisted and the respective file extent items are added to the
+# snapshot's btree.
+sync
+
+# Now create send streams for the snapshots from this new filesystem. For the
+# first snapshot we do a full send while for the second snapshot we do an
+# incremental send.
+_run_btrfs_util_prog send $SCRATCH_MNT/snap1 -f $send_files_dir/1_2.snap
+_run_btrfs_util_prog send -p $SCRATCH_MNT/snap1 $SCRATCH_MNT/snap2 \
+	-f $send_files_dir/2_2.snap
+
+# Create a new filesystem and receive the send streams we just created from the
+# second filesystem. This worked until the linux kernel 4.2, where a regression
+# was introduced. The problem was that the send stream included an incorrect
+# value for the uuid field, which matched a snapshot's uuid (which is different
+# on each filesystem) instead of the snapshot's received_uuid value (which is
+# preserved across different filesystems).
+_scratch_unmount
+_scratch_mkfs >>$seqres.full 2>&1
+_scratch_mount
+
+_run_btrfs_util_prog receive $SCRATCH_MNT -vv -f $send_files_dir/1_2.snap
+_run_btrfs_util_prog receive $SCRATCH_MNT -vv -f $send_files_dir/2_2.snap
+
+echo "File digests in the third filesystem:"
+# Must match the digests we got in the first and second filesystems.
+md5sum $SCRATCH_MNT/snap1/foo | _filter_scratch
+md5sum $SCRATCH_MNT/snap2/foo | _filter_scratch
+
+status=0
+exit

tests/btrfs/111.out

@@ -0,0 +1,14 @@
+QA output created by 111
+wrote 32768/32768 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 4096/4096 bytes at offset 4096
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+File digests in the first filesystem:
+c28418534a020122aca59fd3ff9581b5  SCRATCH_MNT/snap1/foo
+b93cf657bd4e3fa6f6a7f3d1142fd691  SCRATCH_MNT/snap2/foo
+File digests in the second filesystem:
+c28418534a020122aca59fd3ff9581b5  SCRATCH_MNT/snap1/foo
+b93cf657bd4e3fa6f6a7f3d1142fd691  SCRATCH_MNT/snap2/foo
+File digests in the third filesystem:
+c28418534a020122aca59fd3ff9581b5  SCRATCH_MNT/snap1/foo
+b93cf657bd4e3fa6f6a7f3d1142fd691  SCRATCH_MNT/snap2/foo

tests/btrfs/group

@@ -113,3 +113,4 @@
 108 auto quick send clone
 109 auto quick send clone compress
 110 auto quick send
+111 auto quick send