On Tue, Mar 22, 2016 at 12:00:13PM +0800, Eryu Guan wrote: > On Thu, Mar 17, 2016 at 03:56:38PM -0700, Liu Bo wrote: > > This is to test if COW enabled btrfs can end up with single 4k extents > > when doing subpagesize buffered writes. > > What happens if btrfs is mounted with "nodatacow" option? Does it need > to _notrun if cow is disabled? In my test, the test passes if mounting with "nodatacow". Yes, it makes sense to have a _notrun for nodatacow. > > > > > The patch to fix the problem is > > https://patchwork.kernel.org/patch/8527991/ > > > > Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx> > > --- > > v2: - Teach awk to know system's pagesize. > > - Add "Silence is golden" to output. > > - Use local variables to lower case. > > - Add comments to make code clear. > > This should be v3, and this patch was buried in the v2 thread :) Oops, thanks for pointing it out. > > > > > tests/btrfs/027 | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > > tests/btrfs/027.out | 2 ++ > > tests/btrfs/group | 1 + > > 3 files changed, 105 insertions(+) > > create mode 100755 tests/btrfs/027 > > create mode 100644 tests/btrfs/027.out > > > > diff --git a/tests/btrfs/027 b/tests/btrfs/027 > > new file mode 100755 > > index 0000000..19d324b > > --- /dev/null > > +++ b/tests/btrfs/027 > > @@ -0,0 +1,102 @@ > > +#! /bin/bash > > +# FS QA Test 027 > > +# > > +# When btrfs is using cow mode, buffered writes of sub-pagesize can end up with > > +# single 4k extents. > > +# Ref: > > +# "Stray 4k extents with slow buffered writes" > > +# https://www.spinics.net/lists/linux-btrfs/msg52628.html > > After going through this thread, my understanding is that nodatacow > btrfs should pass this test even on unpatched kernel (e.g. v4.5). But > my test on v4.5 kernel failed with nodatacow mount option, pagesize > extent is still found. > I verified it again on my kvm box and it passed with a unpatched v4.5 kernel. Can you please show me the 027.full file? I can't think of a reason for this.. > > +# > > +#----------------------------------------------------------------------- > > +# Copyright (c) 2016 Liu Bo. 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.* > > + > > + # restore expire > > + echo $default_expire > /proc/sys/vm/dirty_expire_centisecs > > +} > > + > > +# get standard environment, filters and checks > > +. ./common/rc > > +. ./common/filter > > + > > +# remove previous $seqres.full before test > > +rm -f $seqres.full > > +echo "Silence is golden" > > + > > +# real QA test starts here > > + > > +# Modify as appropriate. > > +_supported_fs btrfs > > +_supported_os Linux > > +_require_scratch > > +_require_xfs_io_command "fiemap" > > + > > +_scratch_mkfs >> $seqres.full 2>&1 > > +_scratch_mount > > + > > +default_expire=`cat /proc/sys/vm/dirty_expire_centisecs` > > +# Make it flush dirty pages more frequently to make sure we reproduce the bug. > > +echo 50 > /proc/sys/vm/dirty_expire_centisecs > > + > > +tfile=$SCRATCH_MNT/testfile > > +pagesize=$(get_page_size) > > +sublen=$((RANDOM % pagesize)) > > + > > +$XFS_IO_PROG -f -c "pwrite 0 $pagesize" $tfile > /dev/null 2>&1 > > +# write some subpagesize data first. > > +$XFS_IO_PROG -c "pwrite $pagesize $sublen" $tfile > /dev/null 2>&1 > > + > > +# Mix up "abnormal" subpagesize writes with normal pagesize based writes > > +toff=$((pagesize + sublen)) > > +for ((i = 0; i < 10000; i++)) > > +do > > + tlen=$pagesize > > + if [ $((i % 2)) = 0 ]; then > > + tlen=$((pagesize * 3)) > > + fi > > + if [ $((i % 1000)) = 0 ]; then > > + tlen=$((RANDOM % pagesize)) > > + fi > > + > > + $XFS_IO_PROG -c "pwrite $toff $tlen" $tfile > /dev/null 2>&1 > > + toff=$((toff + tlen)) > > +done > > fstests prefers this format: > > for ...; do > ... > done OK, thank you very much, Eryu! Thanks, -liubo > > Thanks, > Eryu > > > + > > +sync > > + > > +# check for single PAGESIZE extent > > +$XFS_IO_PROG -c "fiemap -v" $tfile >> $seqres.full 2>&1 > > +$XFS_IO_PROG -c "fiemap -v" $tfile | \ > > +awk -v pgsize=$pagesize '{n = pgsize/512; if ($4 == n) print $4}' > > + > > +# success, all done > > +status=0 > > +exit > > diff --git a/tests/btrfs/027.out b/tests/btrfs/027.out > > new file mode 100644 > > index 0000000..ef78cda > > --- /dev/null > > +++ b/tests/btrfs/027.out > > @@ -0,0 +1,2 @@ > > +QA output created by 027 > > +Silence is golden > > diff --git a/tests/btrfs/group b/tests/btrfs/group > > index a2fa412..f06d5fe 100644 > > --- a/tests/btrfs/group > > +++ b/tests/btrfs/group > > @@ -29,6 +29,7 @@ > > 024 auto quick compress > > 025 auto quick send clone > > 026 auto quick compress prealloc > > +027 auto > > 029 auto quick clone > > 030 auto quick send > > 031 auto quick subvol clone > > -- > > 2.5.0 > > -- To unsubscribe from this list: send the line "unsubscribe fstests" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
