tests/ts/fallocate/zero-range - master - niceSOFT/util-linux

tests/ts/fallocate/zero-range
92 строки3 KB
WanBingjiang
tests: skip fallocate/zero-range test when /proc/sys/vm/drop_caches is not writable
07 май 2026, 10:27
07 май 2026, 10:275cba9f0
#!/usr/bin/env bash

# This file is part of util-linux.
#
# This file 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; either version 2 of the License, or
# (at your option) any later version.
#
# This file is distributed in the hope that it will 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.
#
# Copyright (C) 2026 Christian Goeschel Ndjomouo <cgoesc2@wgu.edu>

TS_TOPDIR="${0%/*}/../.."
TS_DESC="zero-range"

. "$TS_TOPDIR"/functions.sh
ts_init "$*"
ts_skip_nonroot
[ -w /proc/sys/vm/drop_caches ] || ts_skip "/proc/sys/vm/drop_caches not writable"

ts_check_test_command "$TS_CMD_FALLOCATE"
ts_check_test_command "$TS_CMD_FINDMNT"
ts_check_test_command "$TS_CMD_HEXDUMP"
ts_check_prog "stat"
ts_check_prog "grep"


# The --zero-range option is only supported by ext4 and xfs
fstype="$("$TS_CMD_FINDMNT" -o FSTYPE --noheadings --target "$TS_OUTDIR")"
if [[ ! "$fstype" =~ (xfs|ext4) ]]; then
    ts_skip "unsupported file system type $fstype"
fi

TEST_FILE="${TS_OUTDIR}/${TS_TESTNAME}.data"
# We will use the logical block size to deliberately misalign
# the range to be zeroed, so that we can include two partial
# blocks and one full.
BLKSIZE="$(stat --file-system --format=%s "$TS_OUTDIR")"

# Starting point:
#
# 0        4096     8192     12288
# |AAAAAAAA|BBBBBBBB|DDDDDDDD|
#      |                 |
#    Preallocated zero range

# Expected result:
#
# 0        4096       8192     12288
# |AAAA0000|(00000000)|0000DDDD|
#          |          |
#               ^------- data hole (logically filled)
#
# The zeroes in the data hole are not actually on disk
# the zeroes are merely logical because the extents are
# unwritten.
# However, the zeroes in the other two partial blocks
# are written.
{
  printf "%*s" "$BLKSIZE" '' | tr ' ' '\252'
  printf "%*s" "$BLKSIZE" '' | tr ' ' '\273'
  printf "%*s" "$BLKSIZE" '' | tr ' ' '\335'
} >"$TEST_FILE"

size_before="$(stat --format=%s "$TEST_FILE" 2>>"$TS_ERRLOG")"

"$TS_CMD_FALLOCATE" --zero-range --keep-size --offset $(( BLKSIZE - ( BLKSIZE / 2 ) )) \
                        --length $(( BLKSIZE * 2 )) "$TEST_FILE" >>"$TS_OUTPUT" 2>>"$TS_ERRLOG"

# Due to cache incoherency we have to flush the VFS cache,
# so we can get the correct extent mapping for $TEST_FILE,
# and lseek(... SEEK_HOLE) does not falsely report holes.
echo 3 > /proc/sys/vm/drop_caches 2>>"$TS_ERRLOG"

size_after="$(stat --format=%s "$TEST_FILE" 2>>"$TS_ERRLOG")"

if (( size_before != size_after )); then
    rm -f "$TEST_FILE"
    ts_failed "file size changed unexpectedly (before: $size_before, after: $size_after, block size: $BLKSIZE)"
fi

{
    "$TS_CMD_FALLOCATE" --report-holes "$TEST_FILE" | grep -o 'data holes: 1 holes'
    "$TS_CMD_HEXDUMP" --canonical "$TEST_FILE" | sed -e 's/^[[:alnum:]]*[[:space:]]*//g'
} >>"$TS_OUTPUT" 2>>"$TS_ERRLOG"

rm -f "$TEST_FILE"
ts_finalize