linux-kernel - Re: [PATCH] btrfs:remove redundant index_rbio_pages in raid56_rmw

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Message-ID: <32c9fcf2-e1b4-8d31-a1f4-b07b1d5c1dc5@zoho.com>
Date:   Thu, 29 Sep 2022 01:14:11 -0400
From:   hmsjwzb <hmsjwzb@...o.com>
To:     Qu Wenruo <wqu@...e.com>
Cc:     stringbox8@...o.com, Chris Mason <clm@...com>,
        Josef Bacik <josef@...icpanda.com>,
        David Sterba <dsterba@...e.com>, linux-btrfs@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] btrfs:remove redundant index_rbio_pages in
 raid56_rmw_stripe

Hi Qu,

I test this patch with fstests runs ?

Four btrfs cases failed.

	btrfs/219	btrfs/249	btrfs/253	btrfs/254

Thanks,
Flint

On 9/28/22 23:08, Qu Wenruo wrote:
> 
> 
> On 2022/9/29 09:44, Flint.Wang wrote:
>>    The index_rbio_pages in raid56_rmw_stripe is redundant.
> 
> index_rbio_pages() is to populate the rbio->bio_sectors array.
> 
> In raid56_rmw_stripe() we later calls sector_in_rbio(), which will check if a sector is belonging to bio_lists.
> 
> If not called, all sector will be returned using the sectors in rbio->bio_sectors, not using the sectors in bio lists.
> 
> Have you tried your patch with fstests runs?
> 
> IMHO it should fail a lot of very basic writes in RAID56.
> 
> Thanks,
> Qu
> 
>>    It is invoked in finish_rmw anyway.
>>
>> Signed-off-by: Flint.Wang <hmsjwzb@...o.com>
>> ---
>>   fs/btrfs/raid56.c | 2 --
>>   1 file changed, 2 deletions(-)
>>
>> diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
>> index f6395e8288d69..44266b2c5b86e 100644
>> --- a/fs/btrfs/raid56.c
>> +++ b/fs/btrfs/raid56.c
>> @@ -1546,8 +1546,6 @@ static int raid56_rmw_stripe(struct btrfs_raid_bio *rbio)
>>       if (ret)
>>           goto cleanup;
>>   -    index_rbio_pages(rbio);
>> -
>>       atomic_set(&rbio->error, 0);
>>       /* Build a list of bios to read all the missing data sectors. */
>>       for (total_sector_nr = 0; total_sector_nr < nr_data_sectors;