On Wed, Apr 5, 2017 at 3:14 AM, Qu Wenruo <quwenruo@xxxxxxxxxxxxxx> wrote:
> Btrfs allows inline file extent if and only if
> 1) It's at offset 0
> 2) It's smaller than min(max_inline, page_size)
> Although we don't specify if the size is before compression or after
> compression.
> At least according to current behavior, we are only limiting the size
> after compression.
> 3) It's the only file extent
> So that if we append existing inline extent, it should be converted
> to regular file extents.
>
> However several users in btrfs mail list have reported invalid inline
> file extent, which only meets the first two condition, but with regular
> file extents follows.
follows -> following
>
> The bug is here for a long long time, so long that we have modified
> kernel and btrfs-progs to accept such case, but it's still not designed
> behavior, and must be detected and fixed.
>
> Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
> ---
> tests/btrfs/140 | 120 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> tests/btrfs/140.out | 2 +
> tests/btrfs/group | 1 +
> 3 files changed, 123 insertions(+)
> create mode 100755 tests/btrfs/140
> create mode 100644 tests/btrfs/140.out
>
> diff --git a/tests/btrfs/140 b/tests/btrfs/140
> new file mode 100755
> index 0000000..55f81f2
> --- /dev/null
> +++ b/tests/btrfs/140
> @@ -0,0 +1,120 @@
> +#! /bin/bash
> +# FS QA Test 140
> +#
> +# Check if btrfs will create inline-then-regular file layout.
> +#
> +# Btrfs only allows inline file extent if file is small enough, and any
> +# incoming write enlarges the file beyong max_inline should replace inline
beyong -> beyond
> +# extents with regular extents.
> +# This is a long standing bug, so fsck won't detect it and kernel will allow
> +# normal read on it, but should be avoided.
> +#
> +#-----------------------------------------------------------------------
> +# Copyright (c) 2017 Fujitsu. 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"
> +
> +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
> +
> +# remove previous $seqres.full before test
> +rm -f $seqres.full
> +
> +# real QA test starts here
> +
> +# Modify as appropriate.
> +_supported_fs btrfs
> +_supported_os Linux
> +_require_scratch
> +_require_btrfs_command inspect-internal dump-tree
> +
> +inline_size=2048
> +page_size=$(get_page_size)
> +src_subv="$SCRATCH_MNT/src"
> +dst_subv="$SCRATCH_MNT/dst"
> +loop_counts=$(($LOAD_FACTOR * 4)) #The possibility is over 80%, just in case
> +
> +do_test()
> +{
> + local ret
unused variable
> + _scratch_mkfs > /dev/null 2>&1
> +
> + # specify max_inline and compress explicitly to create
> + # inlined compressed extent
> + _scratch_mount "-o max_inline=$inline_size,compress"
> +
> + # Subvolume id=257
> + _run_btrfs_util_prog subvolume create $src_subv
> +
> + # Page sized data will be compressed to quite small size,
> + # which is about 50 bytes for 4K, 100 bytes for 64K,
> + # far smaller than $inline_size, causing a inlined compressed
> + # file extent
> + $XFS_IO_PROG -f -c "pwrite 0 $page_size" -c "fsync" $src_subv/file \
> + > /dev/null
> +
> + # Subvolume id=258
> + _run_btrfs_util_prog subvolume snapshot $src_subv $dst_subv
> +
> + # Append another page to file in snapshot, since its offset is not
> + # 0, it will cause regular extent, and should convert inline extent
> + # to regular too.
> + $XFS_IO_PROG -c "pwrite $page_size $page_size" $dst_subv/file > /dev/null
> + _scratch_unmount
> +
> + # Fsck won't report inline-then-regular as error, as it's so long
> + # standing that we have no choice but to accept.
> + # So here we use dump-tree to catch inline extent of $dst_subv, and
> + # we need piping stdout, call btrfs-progs directly
I don't understand the last sentence of the comment. Need piping
stdout? What pipe, to where? And call btrfs-progs directly where, what
does it mean?
> + $BTRFS_UTIL_PROG inspect-internal dump-tree -t 258 $SCRATCH_DEV \
> + > $tmp.dump_tree
> + if grep -q inline $tmp.dump_tree; then
> + cat $tmp.dump_tree >> $seqres.full
> + echo "Invalid inline file extent detected"
> + return 1
> + fi
> + return 0
> +}
This is unnecessarily complex to reproduce the issue.
It is enough to:
1) Create a file with an inline extent in the default subvolume (5)
2) Create a snapshot of the default subvolume (can be readonly)
3) Do the second write against the file in the default subvolume
I.e., no need to create a second subvolume/snapshot. The file in the
default subvolume will have the issue.
> +
> +for i in $(seq 1 $loop_counts); do
> + do_test
> + if [ $? -ne 0 ]; then
> + corrupted=$(($corrupted + 1))
> + fi
> +done
> +
> +echo "Corruption possibility: $corrupted/$loop_counts" >> $seqres.full
> +echo "Silence is golden"
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/btrfs/140.out b/tests/btrfs/140.out
> new file mode 100644
> index 0000000..24e90bc
> --- /dev/null
> +++ b/tests/btrfs/140.out
> @@ -0,0 +1,2 @@
> +QA output created by 140
> +Silence is golden
> diff --git a/tests/btrfs/group b/tests/btrfs/group
> index 641d826..e4c76e3 100644
> --- a/tests/btrfs/group
> +++ b/tests/btrfs/group
> @@ -142,3 +142,4 @@
> 137 auto quick send
> 138 auto compress
> 139 auto qgroup
> +140 auto
Add the compress group.
thanks
> --
> 2.9.3
>
>
>
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