Re: [PATCH 02/11] xfs: Check for extent overflow when trivally adding a new extent

Darrick J. Wong
2020-11-14T00:24:41Z

On Fri, Nov 13, 2020 at 04:56:54PM +0530, Chandan Babu R wrote:
> This test verifies that XFS does not cause inode fork's extent count to
> overflow when adding a single extent while there's no possibility of
> splitting an existing mapping (limited to non-realtime files).
>
> Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
> ---
> tests/xfs/522 | 214 ++++++++++++++++++++++++++++++++++++++++++++++
> tests/xfs/522.out | 24 ++++++
> tests/xfs/group | 1 +
> 3 files changed, 239 insertions(+)
> create mode 100755 tests/xfs/522
> create mode 100644 tests/xfs/522.out
>
> diff --git a/tests/xfs/522 b/tests/xfs/522
> new file mode 100755
> index 00000000..a54fe136
> --- /dev/null
> +++ b/tests/xfs/522
> @@ -0,0 +1,214 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2020 Chandan Babu R. All Rights Reserved.
> +#
> +# FS QA Test 522
> +#
> +# Verify that XFS does not cause inode fork's extent count to overflow when
> +# adding a single extent while there's no possibility of splitting an existing
> +# mapping (limited to non-realtime files).
> +
> +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/quota
> +. ./common/inject
> +
> +# remove previous $seqres.full before test
> +rm -f $seqres.full
> +
> +# real QA test starts here
> +
> +_supported_fs xfs
> +_require_scratch
> +_require_xfs_quota
> +_require_xfs_debug
> +_require_xfs_io_command "falloc"
> +_require_xfs_io_error_injection "reduce_max_iextents"
> +_require_xfs_io_error_injection "bmap_alloc_minlen_extent"
> +
> +delalloc_to_written_extent()
> +{
> + echo "* Delalloc to written extent conversion"
> +
> + echo "Format and mount fs"
> + _scratch_mkfs >> $seqres.full
> + _scratch_mount >> $seqres.full
> +
> + testfile=$SCRATCH_MNT/testfile
> + bsize=$(_get_block_size $SCRATCH_MNT)
> +
> + echo "Inject reduce_max_iextents error tag"
> + xfs_io -x -c 'inject reduce_max_iextents' $SCRATCH_MNT
> +
> + nr_blks=$((15 * 2))
> +
> + echo "Create fragmented file"
> + for i in $(seq 0 2 $((nr_blks - 1))); do
> + xfs_io -f -c "pwrite $((i * bsize)) $bsize" -c fsync $testfile >> $seqres.full 2>&1
> + [[ $? != 0 ]] && break
> + done
> +
> + testino=$(stat -c "%i" $testfile)
> +
> + _scratch_unmount >> $seqres.full
> +
> + echo "Verify \$testfile's extent count"
> +
> + nextents=$(_scratch_get_iext_count $testino data || \
> + _fail "Unable to obtain inode fork's extent count")
> + if (( $nextents > 10 )); then
> + echo "Extent count overflow check failed: nextents = $nextents"
> + exit 1
> + fi
> +}
> +
> +falloc_unwritten_extent()
> +{
> + echo "* Fallocate of unwritten extents"
> +
> + echo "Format and mount fs"
> + _scratch_mkfs >> $seqres.full
> + _scratch_mount >> $seqres.full
> +
> + testfile=$SCRATCH_MNT/testfile
> + bsize=$(_get_block_size $SCRATCH_MNT)
> +
> + echo "Inject reduce_max_iextents error tag"
> + xfs_io -x -c 'inject reduce_max_iextents' $SCRATCH_MNT
> +
> + nr_blks=$((15 * 2))
> +
> + echo "Fallocate fragmented file"
> + for i in $(seq 0 2 $((nr_blks - 1))); do
> + xfs_io -f -c "falloc $((i * bsize)) $bsize" $testfile >> $seqres.full 2>&1
> + [[ $? != 0 ]] && break
> + done
> +
> + testino=$(stat -c "%i" $testfile)
> +
> + _scratch_unmount >> $seqres.full
> +
> + echo "Verify \$testfile's extent count"
> +
> + nextents=$(_scratch_get_iext_count $testino data || \
> + _fail "Unable to obtain inode fork's extent count")
> + if (( $nextents > 10 )); then
> + echo "Extent count overflow check failed: nextents = $nextents"
> + exit 1
> + fi
> +}
> +
> +quota_inode_extend()
> +{
> + echo "* Extend quota inodes"
> +
> + echo "Format and mount fs"
> + _scratch_mkfs_sized $((512 * 1024 * 1024)) >> $seqres.full
> + _scratch_mount -o uquota >> $seqres.full
> +
> + testfile=$SCRATCH_MNT/testfile
> + bsize=$(_get_block_size $SCRATCH_MNT)
> +
> + echo "Consume free space"
> + dd if=/dev/zero of=${testfile} bs=${bsize} >> $seqres.full 2>&1
> + sync
> +
> + echo "Create fragmented filesystem"
> + $here/src/punch-alternating $testfile >> $seqres.full
> + sync
> +
> + echo "Inject reduce_max_iextents error tag"
> + xfs_io -x -c 'inject reduce_max_iextents' $SCRATCH_MNT
> +
> + echo "Inject bmap_alloc_minlen_extent error tag"
> + xfs_io -x -c 'inject bmap_alloc_minlen_extent' $SCRATCH_MNT
> +
> + nr_blks=20
> +
> + # This is a rough calculation; It doesn't take block headers into
> + # consideration.
> + # gdb -batch vmlinux -ex 'print sizeof(struct xfs_disk_dquot)'
> + # $1 = 104
> + nr_quotas_per_block=$((bsize / 104))

That's sizeof(xfs_dqblk_t) you want, and it's 136 bytes long.

> + nr_quotas=$((nr_quotas_per_block * nr_blks))
> +
> + echo "Extend uquota file"
> + for i in $(seq 0 $nr_quotas); do

You only have to initialize the first dquot in a dquot file block in
order to allocate the whole block, so you could speed this up with
"seq 0 $nr_quotas_per_block $nr_quotas".

> + chown $i $testfile >> $seqres.full 2>&1
> + [[ $? != 0 ]] && break
> + done
> +
> + _scratch_unmount >> $seqres.full
> +
> + echo "Verify uquota inode's extent count"
> + uquotino=$(_scratch_xfs_db -c sb -c "print uquotino")
> + uquotino=${uquotino##uquotino = }
> +
> + nextents=$(_scratch_get_iext_count $uquotino data || \
> + _fail "Unable to obtain inode fork's extent count")
> + if (( $nextents > 10 )); then
> + echo "Extent count overflow check failed: nextents = $nextents"
> + exit 1
> + fi
> +}
> +
> +directio_write()
> +{
> + echo "* Directio write"
> +
> + echo "Format and mount fs"
> + _scratch_mkfs >> $seqres.full
> + _scratch_mount >> $seqres.full
> +
> + testfile=$SCRATCH_MNT/testfile
> + bsize=$(_get_block_size $SCRATCH_MNT)
> +
> + echo "Inject reduce_max_iextents error tag"
> + xfs_io -x -c 'inject reduce_max_iextents' $SCRATCH_MNT
> +
> + nr_blks=$((15 * 2))
> +
> + echo "Create fragmented file via directio writes"
> + for i in $(seq 0 2 $((nr_blks - 1))); do
> + xfs_io -d -f -c "pwrite $((i * bsize)) $bsize" -c fsync $testfile >> $seqres.full 2>&1

$XFS_IO_PROG -d -f -s -c "pwrite ..." $testfile

"-s" is an undocumented flag that makes the writes synchronous.

> + [[ $? != 0 ]] && break
> + done
> +
> + testino=$(stat -c "%i" $testfile)
> +
> + _scratch_unmount >> $seqres.full
> +
> + echo "Verify \$testfile's extent count"
> +
> + nextents=$(_scratch_get_iext_count $testino data || \

$XFS_IO_PROG -c 'stat' $testfile | grep nextents ?

> + _fail "Unable to obtain inode fork's extent count")
> + if (( $nextents > 10 )); then
> + echo "Extent count overflow check failed: nextents = $nextents"
> + exit 1
> + fi
> +}
> +
> +delalloc_to_written_extent
> +falloc_unwritten_extent
> +quota_inode_extend
> +directio_write

I wonder if these should be separate tests, since they each format the
scratch fs? Or could you format the scratch fs once and test four
different files?

--D

> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/xfs/522.out b/tests/xfs/522.out
> new file mode 100644
> index 00000000..98791aae
> --- /dev/null
> +++ b/tests/xfs/522.out
> @@ -0,0 +1,24 @@
> +QA output created by 522
> +* Delalloc to written extent conversion
> +Format and mount fs
> +Inject reduce_max_iextents error tag
> +Create fragmented file
> +Verify $testfile's extent count
> +* Fallocate of unwritten extents
> +Format and mount fs
> +Inject reduce_max_iextents error tag
> +Fallocate fragmented file
> +Verify $testfile's extent count
> +* Extend quota inodes
> +Format and mount fs
> +Consume free space
> +Create fragmented filesystem
> +Inject reduce_max_iextents error tag
> +Inject bmap_alloc_minlen_extent error tag
> +Extend uquota file
> +Verify uquota inode's extent count
> +* Directio write
> +Format and mount fs
> +Inject reduce_max_iextents error tag
> +Create fragmented file via directio writes
> +Verify $testfile's extent count
> diff --git a/tests/xfs/group b/tests/xfs/group
> index b89c0a4e..1831f0b5 100644
> --- a/tests/xfs/group
> +++ b/tests/xfs/group
> @@ -519,3 +519,4 @@
> 519 auto quick reflink
> 520 auto quick reflink
> 521 auto quick realtime growfs
> +522 auto quick quota
> --
> 2.28.0
>