Re: generic/471 regression with async buffered writes?

[Jens Axboe <axboe@kernel.dk>]

On 8/18/22 10:37 AM, Darrick J. Wong wrote:
> Hi everyone,
> 
> I noticed the following fstest failure on XFS on 6.0-rc1 that wasn't
> there in 5.19:
> 
> --- generic/471.out
> +++ generic/471.out.bad
> @@ -2,12 +2,10 @@
>  pwrite: Resource temporarily unavailable
>  wrote 8388608/8388608 bytes at offset 0
>  XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> -RWF_NOWAIT time is within limits.
> +pwrite: Resource temporarily unavailable
> +(standard_in) 1: syntax error
> +RWF_NOWAIT took  seconds
>  00000000:  aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa  ................
>  *
> -00200000:  bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb  ................
> -*
> -00300000:  aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa  ................
> -*
>  read 8388608/8388608 bytes at offset 0
>  XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> 
> Is this related to the async buffered write changes, or should I keep
> looking?  AFAICT nobody else has mentioned problems with 471...

The test is just broken. It made some odd assumptions on what RWF_NOWAIT
means with buffered writes. There's been a discussion on it previously,
I'll see if I can find the links. IIRC, the tldr is that the test
doesn't really tie RWF_NOWAIT to whether we'll block or not.

-- 
Jens Axboe