tests/generic/500

#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) 2018 Red Hat Inc.  All Rights Reserved.
#
# FS QA Test No. 500
#
# Race test running out of data space with concurrent discard operation on
# dm-thin.
#
# If a user constructs a test that loops repeatedly over below steps on
# dm-thin, block allocation can fail due to discards not having completed
# yet (Fixed by a685557 dm thin: handle running out of data space vs
# concurrent discard):
# 1) fill thin device via filesystem file
# 2) remove file
# 3) fstrim
#
# And this maybe cause a deadlock when racing a fstrim with a filesystem
# (XFS) shutdown. (Fixed by 8c81dd46ef3c Force log to disk before reading
# the AGF during a fstrim)
#
. ./common/preamble
_begin_fstest auto thin trim

# Override the default cleanup function.
_cleanup()
{
	cd /
	rm -f $tmp.*
	_dmthin_cleanup
}

# Import common functions.
. ./common/filter
. ./common/dmthin

_require_scratch_nocheck
_require_dm_target thin-pool

# The unlink below will result in new metadata blocks for btrfs because of CoW,
# and since we've filled the thinp device it'll return EIO, which will make
# btrfs flip read only, making it fail this test when it just won't work right
# for us in the first place.
_exclude_fs btrfs

# Require underlying device support discard
_scratch_mkfs >>$seqres.full 2>&1
_scratch_mount
_require_batched_discard $SCRATCH_MNT
_scratch_unmount

# Create a thin pool and a *slightly smaller* thin volume, it's helpful
# to reproduce the bug
BACKING_SIZE=$((128 * 1024 * 1024 / 512))	# 128M
VIRTUAL_SIZE=$((BACKING_SIZE + 1024))		# 128M + 1k
CLUSTER_SIZE=$((64 * 1024 / 512))		# 64K

_dmthin_init $BACKING_SIZE $VIRTUAL_SIZE $CLUSTER_SIZE 0
_dmthin_set_fail
_dmthin_try_mkfs >> $seqres.full 2>&1 || \
	_notrun "Could not format small thinp filesystem for test"
_dmthin_mount

# There're two bugs at here, one is dm-thin bug, the other is filesystem
# (XFS especially) bug. The dm-thin bug can't handle running out of data
# space with concurrent discard well. Then the dm-thin bug cause fs unmount
# hang when racing a fstrim with a filesystem shutdown.
#
# If both of two bugs haven't been fixed, below test maybe cause deadlock.
# Else if the fs bug has been fixed, but the dm-thin bug hasn't. below test
# will cause the test fail (no deadlock).
# Else the test will pass.
for ((i=0; i<20; i++)); do
	$XFS_IO_PROG -f -c "pwrite -b 64k 0 256M" \
		$SCRATCH_MNT/testfile &>/dev/null
	rm -f $SCRATCH_MNT/testfile
	$FSTRIM_PROG $SCRATCH_MNT
done

_dmthin_check_fs
_dmthin_cleanup

echo "Silence is golden"

# success, all done
status=0
exit