On Thu, Oct 3, 2019 at 11:59 AM Filipe Manana <fdmanana@xxxxxxxxx> wrote: > > On Wed, Oct 2, 2019 at 7:44 PM Josef Bacik <josef@xxxxxxxxxxxxxx> wrote: > > > > I discovered a problem in btrfs where we'd end up pointing at a block we > > hadn't written out yet. This is triggered by a race when two different > > files on two different subvolumes fsync. This test exercises this path > > with dm-log-writes, and then replays the log at every FUA to verify the > > file system is still mountable and the log is replayable. > > > > This test is to verify the fix > > > > btrfs: fix incorrect updating of log root tree > > > > actually fixed the problem. > > > > Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx> > > Reviewed-by: Filipe Manana <fdmanana@xxxxxxxx> > > It's working now. > Confirmed this triggers the bug, and after about 4 hours of this > running with the btrfs patch, it doesn't trigger the bug anymore. > > Thanks! > > > --- > > v1->v2: > > - added the patchname related to this test in the comments and changelog. > > - running fio makes it use 400mib of shared memory, so running 50 of them is > > impossible on boxes that don't have hundreds of gib of RAM. Fixed this to > > just generate a fio config so we can run 1 fio instance with 50 threads which > > makes it not OOM boxes with tiny amounts of RAM. > > - fixed some formatting things that Filipe pointed out. > > > > tests/btrfs/194 | 111 ++++++++++++++++++++++++++++++++++++++++++++ > > tests/btrfs/194.out | 2 + > > tests/btrfs/group | 1 + > > 3 files changed, 114 insertions(+) > > create mode 100755 tests/btrfs/194 > > create mode 100644 tests/btrfs/194.out > > > > diff --git a/tests/btrfs/194 b/tests/btrfs/194 > > new file mode 100755 > > index 00000000..b98064e2 > > --- /dev/null > > +++ b/tests/btrfs/194 > > @@ -0,0 +1,111 @@ > > +#! /bin/bash > > +# SPDX-License-Identifier: GPL-2.0 > > +# Copyright (c) 2019 Facebook. All Rights Reserved. > > +# > > +# FS QA Test 194 > > +# > > +# Test multi subvolume fsync to test a bug where we'd end up pointing at a block > > +# we haven't written. This was fixed by the patch > > +# > > +# btrfs: fix incorrect updating of log root tree > > +# > > +# Will do log replay and check the filesystem. > > +# > > +seq=`basename $0` > > +seqres=$RESULT_DIR/$seq > > +echo "QA output created by $seq" > > + > > +here=`pwd` > > +tmp=/tmp/$$ > > +fio_config=$tmp.fio > > +status=1 # failure is the default! > > +trap "_cleanup; exit \$status" 0 1 2 3 15 > > + > > +_cleanup() > > +{ > > + cd / > > + _log_writes_cleanup &> /dev/null > > + _dmthin_cleanup > > + rm -f $tmp.* > > +} > > + > > +# get standard environment, filters and checks > > +. ./common/rc > > +. ./common/filter > > +. ./common/dmthin > > +. ./common/dmlogwrites > > + > > +# remove previous $seqres.full before test > > +rm -f $seqres.full > > + > > +# real QA test starts here > > + > > +# Modify as appropriate. > > +_supported_fs generic Btw, only forgot about this. Should be: _supported_fs btrfs Eryu can probably fix that at commit time. Thanks. > > +_supported_os Linux > > + > > +# Use thin device as replay device, which requires $SCRATCH_DEV > > +_require_scratch_nocheck > > +# and we need extra device as log device > > +_require_log_writes > > +_require_dm_target thin-pool > > + > > +cat >$fio_config <<EOF > > +[global] > > +readwrite=write > > +fallocate=none > > +bs=4k > > +fsync=1 > > +size=128k > > +EOF > > + > > +for i in $(seq 0 49); do > > + echo "[foo$i]" >> $fio_config > > + echo "filename=$SCRATCH_MNT/$i/file" >> $fio_config > > +done > > + > > +_require_fio $fio_config > > + > > +cat $fio_config >> $seqres.full > > + > > +# Use a thin device to provide deterministic discard behavior. Discards are used > > +# by the log replay tool for fast zeroing to prevent out-of-order replay issues. > > +_test_unmount > > +_dmthin_init $devsize $devsize $csize $lowspace > > +_log_writes_init $DMTHIN_VOL_DEV > > +_log_writes_mkfs >> $seqres.full 2>&1 > > +_log_writes_mark mkfs > > + > > +_log_writes_mount > > + > > +# First create all the subvolumes > > +for i in $(seq 0 49); do > > + $BTRFS_UTIL_PROG subvolume create "$SCRATCH_MNT/$i" > /dev/null > > +done > > + > > +$FIO_PROG $fio_config > /dev/null 2>&1 > > +_log_writes_unmount > > + > > +_log_writes_remove > > +prev=$(_log_writes_mark_to_entry_number mkfs) > > +[ -z "$prev" ] && _fail "failed to locate entry mark 'mkfs'" > > +cur=$(_log_writes_find_next_fua $prev) > > +[ -z "$cur" ] && _fail "failed to locate next FUA write" > > + > > +while [ ! -z "$cur" ]; do > > + _log_writes_replay_log_range $cur $DMTHIN_VOL_DEV >> $seqres.full > > + > > + # We need to mount the fs because btrfsck won't bother checking the log. > > + _dmthin_mount > > + _dmthin_check_fs > > + > > + prev=$cur > > + cur=$(_log_writes_find_next_fua $(($cur + 1))) > > + [ -z "$cur" ] && break > > +done > > + > > +echo "Silence is golden" > > + > > +# success, all done > > +status=0 > > +exit > > diff --git a/tests/btrfs/194.out b/tests/btrfs/194.out > > new file mode 100644 > > index 00000000..7bfd50ff > > --- /dev/null > > +++ b/tests/btrfs/194.out > > @@ -0,0 +1,2 @@ > > +QA output created by 194 > > +Silence is golden > > diff --git a/tests/btrfs/group b/tests/btrfs/group > > index b92cb12c..0d0e1bba 100644 > > --- a/tests/btrfs/group > > +++ b/tests/btrfs/group > > @@ -196,3 +196,4 @@ > > 191 auto quick send dedupe > > 192 auto replay snapshot stress > > 193 auto quick qgroup enospc limit > > +194 auto metadata log volume > > -- > > 2.21.0 > > > > > -- > 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.”