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Test LWB buffer overflow for block cloning
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PR#15634 removes 128K into 2x68K LWB split optimization, since it
was found to cause LWB buffer overflow while trying to write 128KB
TX_CLONE_RANGE record with 1022 block pointers into 68KB buffer,
with multiple VDEVs ZIL.

This commit adds a test for this particular scenario by writing
maximum sizes TX_CLONE_RANE record with 1022 block pointers into
68KB buffer, with two SLOG devices.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by:  Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Ameer Hamza <ahamza@ixsystems.com>
Signed-off-by: Umer Saleem <usaleem@ixsystems.com>
Closes #15672
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usaleem-ix authored and behlendorf committed Jan 19, 2024
1 parent d8b0b60 commit f94a779
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Showing 4 changed files with 94 additions and 1 deletion.
3 changes: 2 additions & 1 deletion tests/runfiles/linux.run
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Expand Up @@ -44,7 +44,8 @@ tests = ['block_cloning_copyfilerange', 'block_cloning_copyfilerange_partial',
'block_cloning_copyfilerange_cross_dataset',
'block_cloning_cross_enc_dataset',
'block_cloning_copyfilerange_fallback_same_txg',
'block_cloning_replay', 'block_cloning_replay_encrypted']
'block_cloning_replay', 'block_cloning_replay_encrypted',
'block_cloning_lwb_buffer_overflow']
tags = ['functional', 'block_cloning']

[tests/functional/chattr:Linux]
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2 changes: 2 additions & 0 deletions tests/test-runner/bin/zts-report.py.in
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Expand Up @@ -305,6 +305,8 @@ elif sys.platform.startswith('linux'):
['SKIP', cfr_reason],
'block_cloning/block_cloning_replay_encrypted':
['SKIP', cfr_reason],
'block_cloning/block_cloning_lwb_buffer_overflow':
['SKIP', cfr_reason],
'block_cloning/block_cloning_copyfilerange_cross_dataset':
['SKIP', cfr_cross_reason],
'block_cloning/block_cloning_copyfilerange_fallback_same_txg':
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1 change: 1 addition & 0 deletions tests/zfs-tests/tests/Makefile.am
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Expand Up @@ -454,6 +454,7 @@ nobase_dist_datadir_zfs_tests_tests_SCRIPTS += \
functional/block_cloning/block_cloning_cross_enc_dataset.ksh \
functional/block_cloning/block_cloning_replay.ksh \
functional/block_cloning/block_cloning_replay_encrypted.ksh \
functional/block_cloning/block_cloning_lwb_buffer_overflow.ksh \
functional/bootfs/bootfs_001_pos.ksh \
functional/bootfs/bootfs_002_neg.ksh \
functional/bootfs/bootfs_003_pos.ksh \
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@@ -0,0 +1,89 @@
#!/bin/ksh -p
#
# CDDL HEADER START
#
# The contents of this file are subject to the terms of the
# Common Development and Distribution License (the "License").
# You may not use this file except in compliance with the License.
#
# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
# or https://opensource.org/licenses/CDDL-1.0.
# See the License for the specific language governing permissions
# and limitations under the License.
#
# When distributing Covered Code, include this CDDL HEADER in each
# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
# If applicable, add the following below this CDDL HEADER, with the
# fields enclosed by brackets "[]" replaced with your own identifying
# information: Portions Copyright [yyyy] [name of copyright owner]
#
# CDDL HEADER END
#

#
# Copyright (c) 2023 by iXsystems, Inc. All rights reserved.
#

. $STF_SUITE/include/libtest.shlib
. $STF_SUITE/tests/functional/block_cloning/block_cloning.kshlib

#
# DESCRIPTION:
# Test for LWB buffer overflow with multiple VDEVs ZIL when 128KB
# block write is split into two 68KB ones, trying to write maximum
# sizes 128KB TX_CLONE_RANGE record with 1022 block pointers into
# 68KB buffer.
#
# STRATEGY:
# 1. Create a pool with multiple VDEVs ZIL
# 2. Write maximum sizes TX_CLONE_RANGE record with 1022 block
# pointers into 68KB buffer
# 3. Sync TXG
# 4. Clone the file
# 5. Synchronize cached writes
#

verify_runnable "global"

if [[ $(linux_version) -lt $(linux_version "4.5") ]]; then
log_unsupported "copy_file_range not available before Linux 4.5"
fi

VDIR=$TEST_BASE_DIR/disk-bclone
VDEV="$VDIR/a $VDIR/b $VDIR/c"
LDEV="$VDIR/e $VDIR/f"

function cleanup
{
datasetexists $TESTPOOL && destroy_pool $TESTPOOL
rm -rf $VDIR
}

log_onexit cleanup

log_assert "Test for LWB buffer overflow with multiple VDEVs ZIL"

log_must rm -rf $VDIR
log_must mkdir -p $VDIR
log_must truncate -s $MINVDEVSIZE $VDEV $LDEV

log_must zpool create -o feature@block_cloning=enabled $TESTPOOL $VDEV \
log mirror $LDEV
log_must zfs create -o recordsize=32K $TESTPOOL/$TESTFS
# Each ZIL log entry can fit 130816 bytes for a block cloning operation,
# so it can store 1022 block pointers. When LWB optimization is enabled,
# an assert is hit when 128KB block write is split into two 68KB ones
# for 2 SLOG devices
log_must dd if=/dev/urandom of=/$TESTPOOL/$TESTFS/file1 bs=32K count=1022 \
conv=fsync
sync_pool $TESTPOOL
log_must clonefile -c /$TESTPOOL/$TESTFS/file1 /$TESTPOOL/$TESTFS/file2
log_must sync

sync_pool $TESTPOOL
log_must have_same_content /$TESTPOOL/$TESTFS/file1 /$TESTPOOL/$TESTFS/file2
typeset blocks=$(get_same_blocks $TESTPOOL/$TESTFS file1 $TESTPOOL/$TESTFS file2)
log_must [ "$blocks" = "$(seq -s " " 0 1021)" ]

log_pass "LWB buffer overflow is not triggered with multiple VDEVs ZIL"

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