On Fri, Jul 08, 2022 at 10:02:04AM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@xxxxxxxxxx>
>
> Make sure that the kernel can handle empty xattr leaf blocks properly,
> since we've screwed this up enough times.
>
> Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> ---
This version looks good to me, thanks for this new case!
Reviewed-by: Zorro Lang <zlang@xxxxxxxxxx>
> v1.1: adopt maintainer's refactoring suggestions, skip v4 filesystems
> from the start, and check that we really get an attr leaf block.
>
> v1.2: eliminate dead code
> ---
> tests/xfs/845 | 117 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 117 insertions(+)
> create mode 100755 tests/xfs/845
>
> diff --git a/tests/xfs/845 b/tests/xfs/845
> new file mode 100755
> index 00000000..c142fba1
> --- /dev/null
> +++ b/tests/xfs/845
> @@ -0,0 +1,117 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2022 Oracle. All Rights Reserved.
> +#
> +# FS QA Test 845
> +#
> +# Make sure that XFS can handle empty leaf xattr blocks correctly. These
> +# blocks can appear in files as a result of system crashes in the middle of
> +# xattr operations, which means that we /must/ handle them gracefully.
> +# Check that read and write verifiers won't trip, that the get/list/setxattr
> +# operations don't stumble over them, and that xfs_repair will offer to remove
> +# the entire xattr fork if the root xattr leaf block is empty.
> +#
> +# Regression test for kernel commit:
> +#
> +# af866926d865 ("xfs: empty xattr leaf header blocks are not corruption")
> +#
> +. ./common/preamble
> +_begin_fstest auto quick attr
> +
> +# Import common functions.
> +. ./common/filter
> +. ./common/attr
> +
> +# real QA test starts here
> +
> +_supported_fs xfs
> +_require_scratch
> +_require_scratch_xfs_crc # V4 is deprecated
> +_fixed_by_kernel_commit af866926d865 "xfs: empty xattr leaf header blocks are not corruption"
> +
> +_scratch_mkfs_xfs | _filter_mkfs >$seqres.full 2>$tmp.mkfs
> +cat $tmp.mkfs >> $seqres.full
> +source $tmp.mkfs
> +_scratch_mount
> +
> +$XFS_IO_PROG -f -c 'pwrite -S 0x58 0 64k' $SCRATCH_MNT/largefile >> $seqres.full
> +$XFS_IO_PROG -f -c "pwrite -S 0x58 0 $isize" $SCRATCH_MNT/smallfile >> $seqres.full
> +
> +smallfile_md5=$(_md5_checksum $SCRATCH_MNT/smallfile)
> +largefile_md5=$(_md5_checksum $SCRATCH_MNT/largefile)
> +
> +# Try to force the creation of a single leaf block in each of three files.
> +# The first one gets a local attr, the second a remote attr, and the third
> +# is left for scrub and repair to find.
> +touch $SCRATCH_MNT/e0
> +touch $SCRATCH_MNT/e1
> +touch $SCRATCH_MNT/e2
> +
> +$ATTR_PROG -s x $SCRATCH_MNT/e0 < $SCRATCH_MNT/smallfile >> $seqres.full
> +$ATTR_PROG -s x $SCRATCH_MNT/e1 < $SCRATCH_MNT/smallfile >> $seqres.full
> +$ATTR_PROG -s x $SCRATCH_MNT/e2 < $SCRATCH_MNT/smallfile >> $seqres.full
> +
> +e0_ino=$(stat -c '%i' $SCRATCH_MNT/e0)
> +e1_ino=$(stat -c '%i' $SCRATCH_MNT/e1)
> +e2_ino=$(stat -c '%i' $SCRATCH_MNT/e2)
> +
> +_scratch_unmount
> +
> +# We used to think that it wasn't possible for empty xattr leaf blocks to
> +# exist, but it turns out that setting a large xattr on a file that has no
> +# xattrs can race with a log flush and crash, which results in an empty
> +# leaf block being logged and recovered. This is rather hard to trip, so we
> +# use xfs_db to turn a regular leaf block into an empty one.
> +make_empty_leaf() {
> + local inum="$1"
> +
> + echo "editing inode $inum" >> $seqres.full
> +
> + magic=$(_scratch_xfs_get_metadata_field hdr.info.hdr.magic "inode $inum" "ablock 0")
> + if [ "$magic" != "0x3bee" ]; then
> + _scratch_xfs_db -x -c "inode $inum" -c "ablock 0" -c print >> $seqres.full
> + _fail "inode $inum ablock 0 is not a leaf block?"
> + fi
> +
> + base=$(_scratch_xfs_get_metadata_field "hdr.freemap[0].base" "inode $inum" "ablock 0")
> +
> + _scratch_xfs_db -x -c "inode $inum" -c "ablock 0" \
> + -c "write -d hdr.count 0" \
> + -c "write -d hdr.usedbytes 0" \
> + -c "write -d hdr.firstused $dbsize" \
> + -c "write -d hdr.freemap[0].size $((dbsize - base))" \
> + -c print >> $seqres.full
> +}
> +
> +make_empty_leaf $e0_ino
> +make_empty_leaf $e1_ino
> +make_empty_leaf $e2_ino
> +
> +_scratch_mount
> +
> +# Check that listxattr/getxattr/removexattr do nothing.
> +$ATTR_PROG -l $SCRATCH_MNT/e0 2>&1 | _filter_scratch
> +$ATTR_PROG -g x $SCRATCH_MNT/e0 2>&1 | _filter_scratch
> +$ATTR_PROG -r x $SCRATCH_MNT/e0 2>&1 | _filter_scratch
> +
> +# Add a small attr to e0
> +$ATTR_PROG -s x $SCRATCH_MNT/e0 < $SCRATCH_MNT/smallfile > /dev/null
> +$ATTR_PROG -l $SCRATCH_MNT/e0 2>&1 | sed -e 's/\([0-9]*\) byte/XXX byte/g' | _filter_scratch
> +small_md5="$($GETFATTR_PROG -n user.x --absolute-names --only-values $SCRATCH_MNT/e0 | _md5_checksum)"
> +test "$small_md5" = "$smallfile_md5" || \
> + echo "smallfile $smallfile_md5 does not match small attr $small_md5"
> +
> +# Add a large attr to e1
> +$ATTR_PROG -s x $SCRATCH_MNT/e1 < $SCRATCH_MNT/largefile > /dev/null
> +$ATTR_PROG -l $SCRATCH_MNT/e1 2>&1 | _filter_scratch
> +large_md5="$($GETFATTR_PROG -n user.x --absolute-names --only-values $SCRATCH_MNT/e1 | _md5_checksum)"
> +test "$large_md5" = "$largefile_md5" || \
> + echo "largefile $largefile_md5 does not match large attr $large_md5"
> +
> +
> +# Leave e2 to try to trip the repair tools, since xfs_repair used to flag
> +# empty leaf blocks incorrectly too.
> +
> +# success, all done
> +status=0
> +exit
>
