btrfs: add a test for the btrfs file extent gap issue

This is a test to validate that we're not adjusting up i_size before
we have the appropriate file extents on disk.  We had a problem
where i_size would be adjusted up without a contiguous range of file
extents, which isn't ok without a special option enabled.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

tests/btrfs/172

@@ -0,0 +1,76 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2020 Facebook.  All Rights Reserved.
+#
+# FS QA Test 172
+#
+# Validate that without no-holes we do not get an i_size that is after a gap in
+# the file extents on disk.  This is fixed by the following patches
+#
+#     btrfs: use the file extent tree infrastructure
+#     btrfs: replace all uses of btrfs_ordered_update_i_size
+#
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+here=`pwd`
+tmp=/tmp/$$
+status=1	# failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	cd /
+	rm -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/dmlogwrites
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+# real QA test starts here
+
+# Modify as appropriate.
+_supported_fs btrfs
+_supported_os Linux
+_require_scratch
+_require_log_writes
+_require_xfs_io_command "sync_range"
+
+_log_writes_init $SCRATCH_DEV
+_log_writes_mkfs "-O ^no-holes" >> $seqres.full 2>&1
+
+# There's not a straightforward way to commit the transaction without also
+# flushing dirty pages, so shorten the commit interval to 1 so we're sure to get
+# a commit with our broken file
+_log_writes_mount -o commit=1
+
+$XFS_IO_PROG -f -c "pwrite 0 5m" $SCRATCH_MNT/file | _filter_xfs_io
+$XFS_IO_PROG -f -c "sync_range -abw 4m 1m" $SCRATCH_MNT/file | _filter_xfs_io
+
+# Now wait for a transaction commit to happen, wait 2x just to be super sure
+sleep 2
+
+_log_writes_unmount
+_log_writes_remove
+
+cur=$(_log_writes_find_next_fua 0)
+echo "cur=$cur" >> $seqres.full
+while [ ! -z "$cur" ]; do
+	_log_writes_replay_log_range $cur $SCRATCH_DEV >> $seqres.full
+
+	# We only care about the fs consistency, so just run fsck, we don't have
+	# to mount the fs to validate it
+	_check_scratch_fs
+
+	cur=$(_log_writes_find_next_fua $(($cur + 1)))
+done
+
+# success, all done
+status=0
+exit

tests/btrfs/172.out

@@ -0,0 +1,3 @@
+QA output created by 172
+wrote 5242880/5242880 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

tests/btrfs/group

@@ -174,6 +174,7 @@
 169 auto quick send
 170 auto quick snapshot
 171 auto quick qgroup
+172 auto quick log replay
 173 auto quick swap
 174 auto quick swap
 175 auto quick swap volume