Re: [PATCH 10/11] xfs: Check for extent overflow when swapping extents

Darrick J. Wong
2020-11-18T02:25:56Z

On Tue, Nov 17, 2020 at 09:05:25PM +0530, Chandan Babu R wrote:
> On Saturday 14 November 2020 5:38:35 AM IST Darrick J. Wong wrote:
> > On Fri, Nov 13, 2020 at 04:57:02PM +0530, Chandan Babu R wrote:
> > > This test verifies that XFS does not cause inode fork's extent count to
> > > overflow when swapping forks across two files.
> > >
> > > Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
> > > ---
> > > tests/xfs/530 | 115 ++++++++++++++++++++++++++++++++++++++++++++++
> > > tests/xfs/530.out | 13 ++++++
> > > tests/xfs/group | 1 +
> > > 3 files changed, 129 insertions(+)
> > > create mode 100755 tests/xfs/530
> > > create mode 100644 tests/xfs/530.out
> > >
> > > diff --git a/tests/xfs/530 b/tests/xfs/530
> > > new file mode 100755
> > > index 00000000..fccc6de7
> > > --- /dev/null
> > > +++ b/tests/xfs/530
> > > @@ -0,0 +1,115 @@
> > > +#! /bin/bash
> > > +# SPDX-License-Identifier: GPL-2.0
> > > +# Copyright (c) 2020 Chandan Babu R. All Rights Reserved.
> > > +#
> > > +# FS QA Test 530
> > > +#
> > > +# Verify that XFS does not cause inode fork's extent count to overflow when
> > > +# swapping forks between 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/inject
> > > +
> > > +# remove previous $seqres.full before test
> > > +rm -f $seqres.full
> > > +
> > > +# real QA test starts here
> > > +
> > > +_supported_fs xfs
> > > +_require_scratch
> > > +_require_xfs_debug
> > > +_require_xfs_scratch_rmapbt
> > > +_require_xfs_io_command "fcollapse"
> > > +_require_xfs_io_command "swapext"
> >
> > FWIW it's going to be a while before the swapext command goes upstream.
> > Right now it's a part of the atomic file range exchange patchset.
>
> Sorry, I didn't understand your statement. I have the following from my Linux
> machine,
>
> root@debian-guest:~# /sbin/xfs_io
> xfs_io> help swapext
> swapext <donorfile> -- Swap extents between files.
>
> Swaps extents between the open file descriptor and the supplied filename.
>
> The above command causes the following code path to be invoked inside the
> kernel (assuming rmapbt feature is enabled),
> xfs_ioc_swapext() => xfs_swap_extents() => xfs_swap_extent_rmap().

Oops. I forgot that my atomic extent swap series *enhances* that
command. Please disregard the above. :/

--D

> >
> > Do you want me to try to speed that up?
> >
> > --D
> >
> > > +_require_xfs_io_error_injection "reduce_max_iextents"
> > > +
> > > +echo "* Swap extent forks"
> > > +
> > > +echo "Format and mount fs"
> > > +_scratch_mkfs >> $seqres.full
> > > +_scratch_mount >> $seqres.full
> > > +
> > > +bsize=$(_get_block_size $SCRATCH_MNT)
> > > +
> > > +srcfile=${SCRATCH_MNT}/srcfile
> > > +donorfile=${SCRATCH_MNT}/donorfile
> > > +
> > > +echo "Create \$donorfile having an extent of length 17 blocks"
> > > +xfs_io -f -c "pwrite -b $((17 * bsize)) 0 $((17 * bsize))" -c fsync $donorfile \
> > > + >> $seqres.full
> > > +
> > > +# After the for loop the donor file will have the following extent layout
> > > +# | 0-4 | 5 | 6 | 7 | 8 | 9 | 10 |
> > > +echo "Fragment \$donorfile"
> > > +for i in $(seq 5 10); do
> > > + start_offset=$((i * bsize))
> > > + xfs_io -f -c "fcollapse $start_offset $bsize" $donorfile >> $seqres.full
> > > +done
> > > +donorino=$(stat -c "%i" $donorfile)
> > > +
> > > +echo "Create \$srcfile having an extent of length 18 blocks"
> > > +xfs_io -f -c "pwrite -b $((18 * bsize)) 0 $((18 * bsize))" -c fsync $srcfile \
> > > + >> $seqres.full
> > > +
> > > +echo "Fragment \$srcfile"
> > > +# After the for loop the src file will have the following extent layout
> > > +# | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7-10 |
> > > +for i in $(seq 1 7); do
> > > + start_offset=$((i * bsize))
> > > + xfs_io -f -c "fcollapse $start_offset $bsize" $srcfile >> $seqres.full
> > > +done
> > > +srcino=$(stat -c "%i" $srcfile)
> > > +
> > > +_scratch_unmount >> $seqres.full
> > > +
> > > +echo "Collect \$donorfile's extent count"
> > > +donor_nr_exts=$(_scratch_get_iext_count $donorino data || \
> > > + _fail "Unable to obtain inode fork's extent count")
> > > +
> > > +echo "Collect \$srcfile's extent count"
> > > +src_nr_exts=$(_scratch_get_iext_count $srcino data || \
> > > + _fail "Unable to obtain inode fork's extent count")
> > > +
> > > +_scratch_mount >> $seqres.full
> > > +
> > > +echo "Inject reduce_max_iextents error tag"
> > > +xfs_io -x -c 'inject reduce_max_iextents' $SCRATCH_MNT
> > > +
> > > +echo "Swap \$srcfile's and \$donorfile's extent forks"
> > > +xfs_io -f -c "swapext $donorfile" $srcfile >> $seqres.full 2>&1
> > > +
> > > +_scratch_unmount >> $seqres.full
> > > +
> > > +echo "Check for \$donorfile's extent count overflow"
> > > +nextents=$(_scratch_get_iext_count $donorino data || \
> > > + _fail "Unable to obtain inode fork's extent count")
> > > +if (( $nextents == $src_nr_exts )); then
> > > + echo "\$donorfile: Extent count overflow check failed"
> > > +fi
> > > +
> > > +echo "Check for \$srcfile's extent count overflow"
> > > +nextents=$(_scratch_get_iext_count $srcino data || \
> > > + _fail "Unable to obtain inode fork's extent count")
> > > +if (( $nextents == $donor_nr_exts )); then
> > > + echo "\$srcfile: Extent count overflow check failed"
> > > +fi
> > > +
> > > +# success, all done
> > > +status=0
> > > +exit
> > > diff --git a/tests/xfs/530.out b/tests/xfs/530.out
> > > new file mode 100644
> > > index 00000000..996af959
> > > --- /dev/null
> > > +++ b/tests/xfs/530.out
> > > @@ -0,0 +1,13 @@
> > > +QA output created by 530
> > > +* Swap extent forks
> > > +Format and mount fs
> > > +Create $donorfile having an extent of length 17 blocks
> > > +Fragment $donorfile
> > > +Create $srcfile having an extent of length 18 blocks
> > > +Fragment $srcfile
> > > +Collect $donorfile's extent count
> > > +Collect $srcfile's extent count
> > > +Inject reduce_max_iextents error tag
> > > +Swap $srcfile's and $donorfile's extent forks
> > > +Check for $donorfile's extent count overflow
> > > +Check for $srcfile's extent count overflow
> > > diff --git a/tests/xfs/group b/tests/xfs/group
> > > index bc3958b3..81a15582 100644
> > > --- a/tests/xfs/group
> > > +++ b/tests/xfs/group
> > > @@ -527,3 +527,4 @@
> > > 527 auto quick
> > > 528 auto quick reflink
> > > 529 auto quick reflink
> > > +530 auto quick
> >
>
>
> --
> chandan
>
>
>