Re: [PATCH 5/7] btrfs: just delete pending bgs if we are aborted

[Nikolay Borisov <nborisov@suse.com>]

On 17.01.19 г. 16:56 ч., David Sterba wrote:
> On Wed, Jan 16, 2019 at 04:22:55PM +0100, David Sterba wrote:
>> On Wed, Jan 16, 2019 at 03:59:20PM +0100, David Sterba wrote:
>>> On Wed, Nov 21, 2018 at 02:05:43PM -0500, Josef Bacik wrote:
>>>> We still need to do all of the accounting cleanup for pending block
>>>> groups if we abort.  So set the ret to trans->aborted so if we aborted
>>>> the cleanup happens and everybody is happy.
>>>>
>>>> Reviewed-by: Omar Sandoval <osandov@fb.com>
>>>> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
>>>> ---
>>>>  fs/btrfs/extent-tree.c | 8 +++++++-
>>>>  1 file changed, 7 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
>>>> index b9b829c8825c..90423b6749b7 100644
>>>> --- a/fs/btrfs/extent-tree.c
>>>> +++ b/fs/btrfs/extent-tree.c
>>>> @@ -10500,11 +10500,17 @@ void btrfs_create_pending_block_groups(struct btrfs_trans_handle *trans)
>>>>  	struct btrfs_root *extent_root = fs_info->extent_root;
>>>>  	struct btrfs_block_group_item item;
>>>>  	struct btrfs_key key;
>>>> -	int ret = 0;
>>>> +	int ret;
>>>>  
>>>>  	if (!trans->can_flush_pending_bgs)
>>>>  		return;
>>>>  
>>>> +	/*
>>>> +	 * If we aborted the transaction with pending bg's we need to just
>>>> +	 * cleanup the list and carry on.
>>>> +	 */
>>>> +	ret = trans->aborted;
>>>
>>> The cleanup is suitable for a separate helper that does only
>>>
>>> while (!list_empty(&trans->new_bgs)) {
>>> 	list_del_init(&block_group->bg_list);
>>> 	btrfs_delayed_refs_rsv_release(fs_info, 1);
>>> }
>>>
>>> and does not rely on the transaction->abort in a function with 'create'
>>> in it's name.
>>>
>>> The related part is in a separate patch that ab-uses the fact that
>>> setting ->abort will trigger the cleanup.
>>>
>>> https://patchwork.kernel.org/patch/10693081/ will then simply call the
>>> halper instead of
>>>
>>> +	/* This cleans up the pending block groups list properly. */
>>> +	if (!trans->aborted)
>>> +		trans->aborted = ret;
>>> +	btrfs_create_pending_block_groups(trans);
>>>
>>> Setting aborted to an error code anywhere else than
>>> __btrfs_abort_transaction does not sound right as it misses the whole
>>> report.
>>
>> Like this:
>>
>> --- a/fs/btrfs/transaction.c
>> +++ b/fs/btrfs/transaction.c
>> @@ -1901,6 +1901,20 @@ static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
>>                 btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
>>  }
>>
>> +static void btrfs_cleanup_pending_block_groups(struct btrfs_trans_handle *trans)
>> +{
>> +       struct btrfs_fs_info *fs_info = trans->fs_info;
>> +       struct btrfs_block_group_cache *block_group;
>> +
>> +       while (!list_empty(&trans->new_bgs)) {
>> +               block_group = list_first_entry(&trans->new_bgs,
>> +                                              struct btrfs_block_group_cache,
>> +                                              bg_list);
>> +               btrfs_delayed_refs_rsv_release(fs_info, 1);
>> +               list_del_init(&block_group->bg_list);
>> +       }
>> +}
>> +
>>  int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
>>  {
>>         struct btrfs_fs_info *fs_info = trans->fs_info;
>> @@ -2270,6 +2284,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
>>         btrfs_scrub_continue(fs_info);
>>  cleanup_transaction:
>>         btrfs_trans_release_metadata(trans);
>> +       btrfs_cleanup_pending_block_groups(trans);
>>         btrfs_trans_release_chunk_metadata(trans);
>>         trans->block_rsv = NULL;
>>         btrfs_warn(fs_info, "Skipping commit of aborted transaction.");
>> ---
>>
>> The call to btrfs_trans_release_chunk_metadata is not duplicated now as it
>> would happen twice in you version (within btrfs_create_pending_block_groups and
>> in transaction commit).
> 
> FYI, this passed the 475 test (with accounting warnings that are
> possibly fixed by the other patches) + no blowups in the following
> tests.

For what is worth 475 doesn't always fail for me - without those
patches. So make sure you have given it a good bashing before deeming it
good.

>