Hi Mark,
Thanks for all your work on this.
Comment on test case is inlined below.
Mark Fasheh wrote on 2015/09/22 14:12 -0700:
On Tue, Sep 22, 2015 at 01:15:44PM -0700, Mark Fasheh wrote:
The entire patch series can be tested with the following xfstests.git
patch, which will be sent to the appropriate list shortly)
https://github.com/markfasheh/xfstests/commit/b09ca51c012824e44546b13862ab1f93a6f2f675
That xfstests patch doesn't apply against latest xfstests.git, attached is
one that does. Git branch is at
git@xxxxxxxxxx:markfasheh/xfstests.git qgroup-drop-snapshot
Sorry about that.
--Mark
--
Mark Fasheh
From: Mark Fasheh <mfasheh@xxxxxxx>
[PATCH] btrfs: add test for quota groups and drop snapshot
Test btrfs quota group consistency operations during snapshot
delete. Btrfs has had long standing issues with drop snapshot
failing to properly account for quota groups. This test crafts
several snapshot trees with shared and exclusive elements. One of
the trees is removed and then quota group consistency is checked.
This issue is fixed by the following linux kernel patches:
Btrfs: use btrfs_get_fs_root in resolve_indirect_ref
Btrfs: keep dropped roots in cache until transaciton commit
btrfs: qgroup: account shared subtree during snapshot delete
Signed-off-by: Mark Fasheh <mfasheh@xxxxxxx>
---
tests/btrfs/104 | 166 ++++++++++++++++++++++++++++++++++++++++++++++++++++
tests/btrfs/104.out | 1 +
tests/btrfs/group | 1 +
3 files changed, 168 insertions(+)
create mode 100644 tests/btrfs/104
create mode 100644 tests/btrfs/104.out
diff --git a/tests/btrfs/104 b/tests/btrfs/104
new file mode 100644
index 0000000..29dc3be
--- /dev/null
+++ b/tests/btrfs/104
@@ -0,0 +1,166 @@
+#! /bin/bash
+# FS QA Test No. btrfs/104
+#
+# Test btrfs quota group consistency operations during snapshot
+# delete. Btrfs has had long standing issues with drop snapshot
+# failing to properly account for quota groups. This test crafts
+# several snapshot trees with shared and exclusive elements. One of
+# the trees is removed and then quota group consistency is checked.
+#
+# This issue is fixed by the following linux kernel patches:
+#
+# Btrfs: use btrfs_get_fs_root in resolve_indirect_ref
+# Btrfs: keep dropped roots in cache until transaciton commit
+# btrfs: qgroup: account shared subtree during snapshot delete
+#
+#-----------------------------------------------------------------------
+# Copyright (C) 2015 SUSE Linux Products GmbH. 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"
+
+tmp=/tmp/$$
+status=1 # failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+ rm -fr $tmp
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# real QA test starts here
+_supported_fs btrfs
+_supported_os Linux
+_require_scratch
+_need_to_be_root
+
+rm -f $seqres.full
+
+# Create an fs tree of a given height at a target location. This is
+# done by agressively creating inline extents to expand the number of
+# nodes required. We also add an traditional extent so that
+# drop_snapshot is forced to walk at least one extent that is not
+# stored in metadata.
+#
+# NOTE: The ability to vary tree height for this test is very useful
+# for debugging problems with drop_snapshot(). As a result we retain
+# that parameter even though the test below always does level 2 trees.
+_explode_fs_tree () {
+ local level=$1;
+ local loc="$2";
+ local bs=4095;
+ local cnt=1;
+ local n;
+
+ if [ -z $loc ]; then
+ echo "specify location for fileset"
+ exit 1;
+ fi
+
+ case $level in
+ 1)# this always reproduces level 1 trees
+ n=10;
I'd prefer a more accurate calculation based on nodesize.
That would allow using any possible nodesize.
For example for $nodesize larger than 4K
l1_min_n = int(($nodesize - 101) / (4095 + 21 + 17)) + 1
And for 4K nodesize,
2 2K inline extent will cause the fs_tree to be 2 level.
As 4K nodeize won't allow 4095 inline extent length.
101 is sizeof(struct btrfs_header).
So $nodesize - 101 is the available space for a leaf.
And 4095 is the maximum inline extent length, 21 is the inline
file_extent header length,offsetof(struct btrfs_file_extent_item,
disk_bytenr).
17 is sizeof(struct btrfs_disk_key).
Above is the maximum value in theory, in fact leaf will be split more
early than hitting the number.
So the max_n should be good enough to create desired tree level, and
make script run a little faster.
+ ;;
+ 2)# this always reproduces level 2 trees
+ n=1500
For level 2 and higher tree, it will be
l2_min_n = l1_min_n * (($nodesize - 101) / 33 +1) ^ ($level - 1)
101 is still header size.
33 is sizeof(struct btrfs_key_ptr)
+ ;;
+ 3)# this always reproduces level 3 trees
+ n=1000000;
+ ;;
+ *)
+ echo "Can't make level $level trees";
+ exit 1;
+ ;;
+ esac
+
+ mkdir -p $loc
+ for i in `seq -w 1 $n`;
+ do
+ dd status=none if=/dev/zero of=$loc/file$i bs=$bs count=$cnt
+ done
+
+ bs=131072
+ cnt=1
+ dd status=none if=/dev/zero of=$loc/extentfile bs=$bs count=$cnt
+}
+
+# Force the default leaf size as the calculations for making our btree
+# heights are based on that.
+run_check _scratch_mkfs "--nodesize 16384"
When using given nodesize, it's better to consider other arch like AA64
or other arch which support 64K pagesize.
(btrfs doesn't support subpage size nodesize, which means if using
nodesize smaller than pagesize, it won't be mounted)
I got informed several times when submitting qgroup related test case.
See btrfs/017 and btrfs/091.
But on the other hand, using 64K nodesize is somewhat overkilled and
will make the test takes more time.
If it's OK to ignore 64K pagesize case, I'd prefer to use 4K nodesize,
which will be much faster to create fs tree with 2~3 levels.
+_scratch_mount
+
+# populate the default subvolume and create a snapshot ('snap1')
+_explode_fs_tree 1 $SCRATCH_MNT/files
+_run_btrfs_util_prog subvolume snapshot $SCRATCH_MNT $SCRATCH_MNT/snap1
+
+# create new btree nodes in this snapshot. They will become shared
+# with the next snapshot we create.
+_explode_fs_tree 1 $SCRATCH_MNT/snap1/files-snap1
+
+# create our final snapshot ('snap2'), populate it with
+# exclusively owned nodes.
+#
+# As a result of this action, snap2 will get an implied ref to the
+# 128K extent created in the default subvolume.
+_run_btrfs_util_prog subvolume snapshot $SCRATCH_MNT/snap1 $SCRATCH_MNT/snap2
+_explode_fs_tree 1 $SCRATCH_MNT/snap2/files-snap2
+
+# Enable qgroups now that we have our filesystem prepared. This
+# will kick off a scan which we will have to wait for.
+_run_btrfs_util_prog quota enable $SCRATCH_MNT
+_run_btrfs_util_prog quota rescan -w $SCRATCH_MNT
+
+# Remount to clear cache, force everything to disk
+_scratch_unmount
+_scratch_mount
Is there anything special that needs to use umount/mount other than sync?
+
+# Finally, delete snap1 to trigger btrfs_drop_snapshot(). This
+# snapshot is most interesting to delete because it will cause some
+# nodes to go exclusively owned for snap2, while some will stay shared
+# with the default subvolume. That exercises a maximum of the drop
+# snapshot/qgroup interactions.
+#
+# snap2s imlied ref from to the 128K extent in files/ can be lost by
+# the root finding code in qgroup accounting due to snap1 no longer
+# providing a path to it. This was fixed by the first two patches
+# referenced above.
+_run_btrfs_util_prog subvolume delete $SCRATCH_MNT/snap1
+
+# There is no way from userspace to force btrfs_drop_snapshot to run
+# at a given time (even via mount/unmount). We must wait for it to
+# start and complete. This is the shortest time on my tests systems I
+# have found which always allows drop_snapshot to run to completion.
+sleep 45
Does "btrfs subv delete -c" help here?
+
+_scratch_unmount
+
+# generate a qgroup report and look for inconsistent groups
+# - don't use _run_btrfs_util_prog here as it captures the output and
+# we need to grep it.
+$BTRFS_UTIL_PROG check --qgroup-report $SCRATCH_DEV 2>&1 | grep -E -q "Counts for qgroup.*are different"
+if [ $? -ne 0 ]; then
+ status=0
+fi
Quite a nice idea to use btrfsck to check qgroup validation.
But I don't see the reason not to use _run_btrfS_util_progs, as I don't
think it's needed to grep.
If there is a bug in return value of btrfsck, then I'm OK with it as a
workaround.
But if btrfsck --qgroup-report will return non-zero when it finds a
qgroup mismatch, I think is better to just call _run_btrfs_util_prog, as
it has judgment for return value check.
Thanks,
Qu
+
+exit
diff --git a/tests/btrfs/104.out b/tests/btrfs/104.out
new file mode 100644
index 0000000..1ed84bc
--- /dev/null
+++ b/tests/btrfs/104.out
@@ -0,0 +1 @@
+QA output created by 104
diff --git a/tests/btrfs/group b/tests/btrfs/group
index e92a65a..6218adf 100644
--- a/tests/btrfs/group
+++ b/tests/btrfs/group
@@ -106,3 +106,4 @@
101 auto quick replace
102 auto quick metadata enospc
103 auto quick clone compress
+104 auto qgroup
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
