diff options
author | Qu Wenruo <wqu@suse.com> | 2023-01-10 15:14:17 +0800 |
---|---|---|
committer | David Sterba <dsterba@suse.com> | 2023-01-11 20:04:18 +0100 |
commit | 75181406b4eafacc531ff2ee5fb032bd93317e2b (patch) | |
tree | c767af09353a87be67b1f35a3f8b861ae6902cac /fs | |
parent | ed02363fbbed52a3f5ea0d188edd09045a806eb5 (diff) | |
download | linux-stable-75181406b4eafacc531ff2ee5fb032bd93317e2b.tar.gz linux-stable-75181406b4eafacc531ff2ee5fb032bd93317e2b.tar.bz2 linux-stable-75181406b4eafacc531ff2ee5fb032bd93317e2b.zip |
btrfs: qgroup: do not warn on record without old_roots populated
[BUG]
There are some reports from the mailing list that since v6.1 kernel, the
WARN_ON() inside btrfs_qgroup_account_extent() gets triggered during
rescan:
WARNING: CPU: 3 PID: 6424 at fs/btrfs/qgroup.c:2756 btrfs_qgroup_account_extents+0x1ae/0x260 [btrfs]
CPU: 3 PID: 6424 Comm: snapperd Tainted: P OE 6.1.2-1-default #1 openSUSE Tumbleweed 05c7a1b1b61d5627475528f71f50444637b5aad7
RIP: 0010:btrfs_qgroup_account_extents+0x1ae/0x260 [btrfs]
Call Trace:
<TASK>
btrfs_commit_transaction+0x30c/0xb40 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6]
? start_transaction+0xc3/0x5b0 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6]
btrfs_qgroup_rescan+0x42/0xc0 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6]
btrfs_ioctl+0x1ab9/0x25c0 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6]
? __rseq_handle_notify_resume+0xa9/0x4a0
? mntput_no_expire+0x4a/0x240
? __seccomp_filter+0x319/0x4d0
__x64_sys_ioctl+0x90/0xd0
do_syscall_64+0x5b/0x80
? syscall_exit_to_user_mode+0x17/0x40
? do_syscall_64+0x67/0x80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fd9b790d9bf
</TASK>
[CAUSE]
Since commit e15e9f43c7ca ("btrfs: introduce
BTRFS_QGROUP_RUNTIME_FLAG_NO_ACCOUNTING to skip qgroup accounting"), if
our qgroup is already in inconsistent state, we will no longer do the
time-consuming backref walk.
This can leave some qgroup records without a valid old_roots ulist.
Normally this is fine, as btrfs_qgroup_account_extents() would also skip
those records if we have NO_ACCOUNTING flag set.
But there is a small window, if we have NO_ACCOUNTING flag set, and
inserted some qgroup_record without a old_roots ulist, but then the user
triggered a qgroup rescan.
During btrfs_qgroup_rescan(), we firstly clear NO_ACCOUNTING flag, then
commit current transaction.
And since we have a qgroup_record with old_roots = NULL, we trigger the
WARN_ON() during btrfs_qgroup_account_extents().
[FIX]
Unfortunately due to the introduction of NO_ACCOUNTING flag, the
assumption that every qgroup_record would have its old_roots populated
is no longer correct.
Fix the false alerts and drop the WARN_ON().
Reported-by: Lukas Straub <lukasstraub2@web.de>
Reported-by: HanatoK <summersnow9403@gmail.com>
Fixes: e15e9f43c7ca ("btrfs: introduce BTRFS_QGROUP_RUNTIME_FLAG_NO_ACCOUNTING to skip qgroup accounting")
CC: stable@vger.kernel.org # 6.1
Link: https://lore.kernel.org/linux-btrfs/2403c697-ddaf-58ad-3829-0335fc89df09@gmail.com/
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/btrfs/qgroup.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index d275bf24b250..00851c86aa8a 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -2765,9 +2765,19 @@ int btrfs_qgroup_account_extents(struct btrfs_trans_handle *trans) /* * Old roots should be searched when inserting qgroup - * extent record + * extent record. + * + * But for INCONSISTENT (NO_ACCOUNTING) -> rescan case, + * we may have some record inserted during + * NO_ACCOUNTING (thus no old_roots populated), but + * later we start rescan, which clears NO_ACCOUNTING, + * leaving some inserted records without old_roots + * populated. + * + * Those cases are rare and should not cause too much + * time spent during commit_transaction(). */ - if (WARN_ON(!record->old_roots)) { + if (!record->old_roots) { /* Search commit root to find old_roots */ ret = btrfs_find_all_roots(&ctx, false); if (ret < 0) |