From: Boris Burkov <boris@bur.io>
To: linux-btrfs@vger.kernel.org, kernel-team@fb.com, fstests@vger.kernel.org
Subject: [PATCH v2] btrfs/310: test qgroup deletion
Date: Tue, 23 Jan 2024 10:45:12 -0800 [thread overview]
Message-ID: <ce4a79cafb6790ef6d1e141d65195f72f469ae4d.1706035378.git.boris@bur.io> (raw)
When using squotas, an extent's OWNER_REF can long outlive the subvolume
that is the owner, since it could pick up a different reference that
keeps it around, but the subvolume can go away.
Test this case, as originally, it resulted in a read only btrfs.
Since we can blow up the subvolume in the same transaction as the extent
is written, we can also increment the usage of a non-existent subvolume.
This leaves an OWNER_REF behind with no corresponding incremented usage
in a qgroup, so if we re-create that qgroup, we can then underflow its
usage.
Both of these cases are fixed in the kernel by disallowing
creating subvol qgroups and by disallowing deleting qgroups that still
have usage.
Signed-off-by: Boris Burkov <boris@bur.io>
---
Changelog:
v2:
- removed enable quota helper
- removed unneeded commented cleanup boilerplate
- change test number 304 -> 310 (based on v2024.01.14)
tests/btrfs/301 | 14 ++------
tests/btrfs/310 | 83 +++++++++++++++++++++++++++++++++++++++++++++
tests/btrfs/310.out | 6 ++++
3 files changed, 91 insertions(+), 12 deletions(-)
create mode 100755 tests/btrfs/310
create mode 100644 tests/btrfs/310.out
diff --git a/tests/btrfs/301 b/tests/btrfs/301
index db4697247..4c1127aa0 100755
--- a/tests/btrfs/301
+++ b/tests/btrfs/301
@@ -157,16 +157,6 @@ do_enospc_falloc()
do_falloc $file $sz
}
-enable_quota()
-{
- local mode=$1
-
- [ $mode == "n" ] && return
- arg=$([ $mode == "s" ] && echo "--simple")
-
- $BTRFS_UTIL_PROG quota enable $arg $SCRATCH_MNT
-}
-
get_subvid()
{
_btrfs_get_subvolid $SCRATCH_MNT subv
@@ -186,7 +176,7 @@ prepare()
{
_scratch_mkfs >> $seqres.full
_scratch_mount
- enable_quota "s"
+ $BTRFS_UTIL_PROG quota enable --simple $SCRATCH_MNT
$BTRFS_UTIL_PROG subvolume create $subv >> $seqres.full
local subvid=$(get_subvid)
set_subvol_limit $subvid $limit
@@ -397,7 +387,7 @@ enable_mature()
# Sync before enabling squotas to reliably *not* count the writes
# we did before enabling.
sync
- enable_quota "s"
+ $BTRFS_UTIL_PROG quota enable --simple $SCRATCH_MNT
set_subvol_limit $subvid $limit
_scratch_cycle_mount
usage=$(get_subvol_usage $subvid)
diff --git a/tests/btrfs/310 b/tests/btrfs/310
new file mode 100755
index 000000000..02714d261
--- /dev/null
+++ b/tests/btrfs/310
@@ -0,0 +1,83 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2024 Meta Platforms, Inc. All Rights Reserved.
+#
+# FS QA Test 310
+#
+# Test various race conditions between qgroup deletion and squota writes
+#
+. ./common/preamble
+_begin_fstest auto quick qgroup subvol clone
+
+# Import common functions.
+. ./common/reflink
+
+# real QA test starts here
+
+# Modify as appropriate.
+_supported_fs btrfs
+_require_scratch_reflink
+_require_cp_reflink
+_require_scratch_enable_simple_quota
+_require_no_compress
+
+_fixed_by_kernel_commit xxxxxxxxxxxx "btrfs: forbid deleting live subvol qgroup"
+_fixed_by_kernel_commit xxxxxxxxxxxx "btrfs: forbid creating subvol qgroups"
+
+subv1=$SCRATCH_MNT/subv1
+subv2=$SCRATCH_MNT/subv2
+
+prepare()
+{
+ _scratch_mkfs >> $seqres.full
+ _scratch_mount
+ $BTRFS_UTIL_PROG quota enable --simple $SCRATCH_MNT
+ $BTRFS_UTIL_PROG subvolume create $subv1 >> $seqres.full
+ $BTRFS_UTIL_PROG subvolume create $subv2 >> $seqres.full
+ $XFS_IO_PROG -fc "pwrite -q 0 128K" $subv1/f
+ _cp_reflink $subv1/f $subv2/f
+}
+
+# An extent can long outlive its owner. Test this by deleting the owning
+# subvolume, committing the transaction, then deleting the reflinked copy.
+# Deleting the copy will attempt to free space from the missing owner, which
+# should be a no-op.
+free_from_deleted_owner()
+{
+ echo "free from deleted owner"
+ prepare
+ subvid1=$(_btrfs_get_subvolid $SCRATCH_MNT subv1)
+
+ $BTRFS_UTIL_PROG filesystem sync $SCRATCH_MNT
+ $BTRFS_UTIL_PROG subvolume delete $subv1 >> $seqres.full
+ $BTRFS_UTIL_PROG qgroup destroy 0/$subvid1 $SCRATCH_MNT >> $seqres.full
+ $BTRFS_UTIL_PROG filesystem sync $SCRATCH_MNT
+ rm $subv2/f
+ _scratch_unmount
+}
+
+# A race where we delete the owner in the same transaction as writing the
+# extent leads to incrementing the squota usage of the missing qgroup.
+# This leaves behind an owner ref with an owner id that cannot exist, so
+# freeing the extent now frees from that qgroup, but there has never
+# been a corresponding usage to free.
+add_to_deleted_owner()
+{
+ echo "add to deleted owner"
+ prepare
+ subvid1=$(_btrfs_get_subvolid $SCRATCH_MNT subv1)
+
+ $BTRFS_UTIL_PROG subvolume delete $subv1 >> $seqres.full
+ $BTRFS_UTIL_PROG qgroup destroy 0/$subvid1 $SCRATCH_MNT >> $seqres.full
+ $BTRFS_UTIL_PROG filesystem sync $SCRATCH_MNT
+ $BTRFS_UTIL_PROG qgroup create 0/$subvid1 $SCRATCH_MNT >> $seqres.full
+ rm $subv2/f
+ _scratch_unmount
+}
+
+free_from_deleted_owner
+add_to_deleted_owner
+
+# success, all done
+status=0
+exit
diff --git a/tests/btrfs/310.out b/tests/btrfs/310.out
new file mode 100644
index 000000000..d7d4bc0ae
--- /dev/null
+++ b/tests/btrfs/310.out
@@ -0,0 +1,6 @@
+QA output created by 310
+free from deleted owner
+ERROR: unable to destroy quota group: Device or resource busy
+add to deleted owner
+ERROR: unable to destroy quota group: Device or resource busy
+ERROR: unable to create quota group: Invalid argument
--
2.43.0
next reply other threads:[~2024-01-23 18:44 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-23 18:45 Boris Burkov [this message]
2024-01-24 12:26 ` [PATCH v2] btrfs/310: test qgroup deletion Filipe Manana
2024-03-01 14:12 ` Zorro Lang
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