On 05/22/2018 08:35 PM, Nikolay Borisov wrote:
>
>
> On 22.05.2018 15:02, David Sterba wrote:
>> On Tue, May 22, 2018 at 07:05:14PM +0800, Su Yue wrote:
>>> Hi Liu and David,
>>> During my local xfstests on kdave/for-next, btrfs/139 failed and
>>> btrfs BUG_ON due to qgroup rescan.
>>> The bisect result is commit 560215eb3f32("Merge branch
>>> 'ext/liubo/search-cleanups-wip' into for-next-next-v4.18-20180521")
>>> which seems merged this patchset.
>>> The dmesg file is attached.
>>>
>>> On 05/18/2018 11:00 AM, Liu Bo wrote:
>>>> Here are a collection of patches I did for btrfs_search_slot().
>>>>
>>>> v2: more explicit commit log for each patch.
>>>>
>>>> Liu Bo (6):
>>>> Btrfs: remove superfluous free_extent_buffer
>>>> Btrfs: use more straightforward extent_buffer_uptodate
>>>> Btrfs: move get root of btrfs_search_slot to a helper
>>>> Btrfs: remove unused check of skip_locking
>>>> Btrfs: grab write lock directly if write_lock_level is the max level
>>>> Btrfs: remove always true check in unlock_up
>>>>
>>>> fs/btrfs/ctree.c | 121
>>>> +++++++++++++++++++++++++++++++++----------------------
>>>> 1 file changed, 73 insertions(+), 48 deletions(-)
>>>>
>>>
>>>
>>
>>> [ 46.129166] BTRFS info (device vdb): disk space caching is enabled
>>> [ 46.130545] BTRFS info (device vdb): has skinny extents
>>> [ 46.171386] mount (2798) used greatest stack depth: 12920 bytes left
>>> [ 46.508170] BTRFS: device fsid 83a117c7-a9ea-4bf5-b42f-7092078610d5
>>> devid 1 transid 5 /dev/vdc
>>> [ 46.562428] BTRFS info (device vdc): disk space caching is enabled
>>> [ 46.563690] BTRFS info (device vdc): has skinny extents
>>> [ 46.564563] BTRFS info (device vdc): flagging fs with big metadata
>>> feature
>>> [ 46.587441] BTRFS info (device vdc): checking UUID tree
>>> [ 46.766765] BTRFS info (device vdb): disk space caching is enabled
>>> [ 46.768197] BTRFS info (device vdb): has skinny extents
>>> [ 46.875534] run fstests btrfs/139 at 2018-05-22 18:40:36
>>> [ 47.559411] BTRFS: device fsid 065f3825-057e-451f-8722-0d94d4a3f36f
>>> devid 1 transid 5 /dev/vdc
>>> [ 47.612001] BTRFS info (device vdc): disk space caching is enabled
>>> [ 47.613254] BTRFS info (device vdc): has skinny extents
>>> [ 47.614147] BTRFS info (device vdc): flagging fs with big metadata
>>> feature
>>> [ 47.632377] BTRFS info (device vdc): checking UUID tree
>>> [ 47.681656] btrfs (3176) used greatest stack depth: 12632 bytes left
>>> [ 47.691156] ------------[ cut here ]------------
>>> [ 47.692084] kernel BUG at fs/btrfs/locking.c:286!
>>
>> I saw the crash too but did not investigate the root cause. So I'll
>> remove the branch from for-next until it's fixed. Thanks for the report.
>
> I think the problem stems from Qu's patch, which sets search_commit_root
> =1 but doesn't set skip_locking, as a result we don't lock the tree when
> we obtain a reference to the root node, yet later when traversing the
> tree due to skip_locking not being set we try to lock it, and this
> causes btrfs_assert_tree_locked to triggers. Can you test whether the
> following diff solves the issues:
>
>
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index bc19a7d11c98..23fadb640c59 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -2702,6 +2702,7 @@ static void btrfs_qgroup_rescan_worker(struct
> btrfs_work *work)
> * should be recorded by qgroup
> */
> path->search_commit_root = 1;
> + path->skip_locking = 1;
>
> err = 0;
> while (!err && !btrfs_fs_closing(fs_info)) {
>
>
> If it does, this only means we need to make skip_locking = 1 being
> conditional on search_commit_root being set and this situation should be
> handled in btrfs_search_slot.After patching the change, btrfs/139 passes without BUG_ON. Thanks, Su > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > >
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