Re: [PATCH] generic: test exceeding max file size via INSERT_RANGE

Darrick J. Wong
2018-04-17T00:34:49Z

On Mon, Apr 16, 2018 at 02:24:35PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> Note: this test will fail on ext4 and xfs until the fixes are applied.

Oooh, a regression test! Yay!

> -----8<-----
>
> Test how the "insert range" fallocate operation interacts with the
> maximum file size (s_maxbytes).
>
> - Shift extents past the max file size (exposes an ext4 bug).
> - Increase i_size past the max file size (exposes an xfs bug).
>
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
> tests/generic/484 | 115 ++++++++++++++++++++++++++++++++++++++++++
> tests/generic/484.out | 4 ++
> tests/generic/group | 1 +
> 3 files changed, 120 insertions(+)
> create mode 100755 tests/generic/484
> create mode 100644 tests/generic/484.out
>
> diff --git a/tests/generic/484 b/tests/generic/484
> new file mode 100755
> index 00000000..7b40b3c3
> --- /dev/null
> +++ b/tests/generic/484
> @@ -0,0 +1,115 @@
> +#! /bin/bash
> +# FS QA Test No. 484
> +#
> +# Regression test for:
> +# ???????????? ("ext4: prevent right-shifting extents beyond EXT_MAX_BLOCKS")
> +# ???????????? ("xfs: prevent creating negative-sized file via INSERT_RANGE")
> +#
> +#-----------------------------------------------------------------------
> +# Copyright (c) 2018 Google, Inc. All Rights Reserved.
> +#
> +# 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"
> +
> +status=1 # failure is the default!
> +trap "_cleanup; exit \$status" 0 1 2 3 15
> +
> +_cleanup()
> +{
> + cd /
> + rm -f $testfile
> +}
> +
> +# get standard environment, filters and checks
> +. ./common/rc
> +. ./common/filter
> +
> +# remove previous $seqres.full before test
> +rm -f $seqres.full
> +
> +# real QA test starts here
> +_supported_fs generic
> +_supported_os Linux
> +_require_test
> +_require_math
> +_require_xfs_io_command "falloc" "-k"
> +_require_xfs_io_command "finsert"
> +_require_xfs_io_command "truncate"
> +
> +# Get the maximum size of a file in $TEST_DIR (s_maxbytes). On ext4 this will
> +# be UINT32_MAX * block_size, but other filesystems may allow up to LLONG_MAX.
> +get_max_file_size()
> +{
> + local testfile=$TEST_DIR/maxfilesize.$seq
> + local l=0
> + local r=9223372036854775807 # LLONG_MAX
> +
> + rm -f $testfile
> + while (( l < r )); do
> + # Use _math() to avoid signed integer overflow.
> + local m=$(_math "($l + $r + 1) / 2")
> + if $XFS_IO_PROG -f -c "truncate $m" $testfile \
> + |& grep -q 'File too large'
> + then
> + r=$(( m - 1 ))
> + else
> + l=$m
> + fi
> + done
> + echo $l
> +}

This will also be useful for generic/30[34], but I'll convert those
after this lands.

> +
> +block_size=$(_get_block_size $TEST_DIR)

_get_file_block_size, for filesystems whose minimum file mapping size is
larger than a filesystem block.

(Currently this is theoretical because the only fs that does that is
ocfs2, and ocfs2 doesn't know about INSERT_RANGE.)

> +max_file_size=$(get_max_file_size)
> +max_blocks=$((max_file_size / block_size))
> +testfile=$TEST_DIR/testfile.$seq
> +
> +echo "# With KEEP_SIZE"
> +rm -f "$testfile"
> +
> +# Add an extent at the beginning of the file. With ext4, this is needed to
> +# reproduce the bug where the extents appear out of order later.
> +$XFS_IO_PROG -f -c "falloc 0 $((2 * block_size))" "$testfile"
> +
> +# Add an extent just below s_maxbytes, without changing i_size (i.e. with -k).
> +# The out-of-order extents bug can't be reproduced if i_size is changed, because
> +# then the range insertion fails due to the new i_size being > s_maxbytes.
> +$XFS_IO_PROG -c "falloc -k $(( (max_blocks - 1) * $block_size )) $block_size" \
> + "$testfile"
> +
> +# Insert an extent at the beginning of the file. With the ext4 bug, this caused
> +# the logical block number of the extent just below s_maxbytes to wrap around,
> +# causing the extents to get out of order, causing corruption detected by
> +# e2fsck. With the fix, the range insertion fails with EINVAL. Though, with
> +# xfs and f2fs the insertion succeeds, resulting in extents beyond s_maxbytes,
> +# but there is no wraparound -- which is arguably okay. So we allow either
> +# behavior and just rely on fsck detecting if something went wrong.
> +$XFS_IO_PROG -c "finsert 0 $((2 * block_size))" "$testfile" &>>$seqres.full
> +
> +# Also do the same test, but with changing i_size (i.e. without -k). The
> +# insertion should fail with EFBIG. This exposed an XFS bug where i_size + len
> +# underwent signed overflow, resulting in a negative-sized file.
> +echo "# Without KEEP_SIZE"
> +rm -f "$testfile"
> +$XFS_IO_PROG -f -c "falloc 0 $((2 * block_size))" "$testfile"
> +$XFS_IO_PROG -c "falloc $(( (max_blocks - 1) * $block_size )) $block_size" \
> + "$testfile"
> +$XFS_IO_PROG -c "finsert 0 $((2 * block_size))" "$testfile"

Heh. :)

/me goes to try patch + test.

--D

> +
> +status=0
> +exit
> diff --git a/tests/generic/484.out b/tests/generic/484.out
> new file mode 100644
> index 00000000..4def4fc0
> --- /dev/null
> +++ b/tests/generic/484.out
> @@ -0,0 +1,4 @@
> +QA output created by 484
> +# With KEEP_SIZE
> +# Without KEEP_SIZE
> +fallocate: File too large
> diff --git a/tests/generic/group b/tests/generic/group
> index ea8e51b3..3f93dc4d 100644
> --- a/tests/generic/group
> +++ b/tests/generic/group
> @@ -486,3 +486,4 @@
> 481 auto quick log metadata
> 482 auto metadata replay
> 483 auto quick log metadata
> +484 auto quick insert
> --
> 2.17.0.484.g0c8726318c-goog
>
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