On Wed, Apr 5, 2017 at 5:00 PM, Filipe Manana <fdman...@gmail.com> wrote:
> On Wed, Apr 5, 2017 at 3:14 AM, Qu Wenruo <quwen...@cn.fujitsu.com> 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 <quwen...@cn.fujitsu.com>
>> ---
>> 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.
Even simpler:
1) Create the file with the data that results in the inline extent
2) fsync the file or call sync
3) Do the second write to the file
4) fsync the file, call sync or unmount the fs
No need for creation of any snapshot/subvolume.
Basically what you had here is a shorter version of btrfs/137 forced
with mount option -o compress.
thanks
>
>> +
>> +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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>
>
>
> --
> Filipe David Manana,
>
> “Whether you think you can, or you think you can't — you're right.”
--
Filipe David Manana,
“Whether you think you can, or you think you can't — you're right.”
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