Re: [PATCH 6.1 00/73] 6.1.119-rc1 review

[Chuck Lever III]

> On Nov 23, 2024, at 2:25 AM, Pavel Machek <pavel@xxxxxxx> wrote:
> 
> Hi!
> 
>> This is the start of the stable review cycle for the 6.1.119 release.
>> There are 73 patches in this series, all will be posted as a response
>> to this one.  If anyone has any issues with these being applied, please
>> let me know.
> 
>> Chuck Lever <chuck.lever@xxxxxxxxxx>
>>    NFSD: Limit the number of concurrent async COPY operations
> 
> @@ -1782,10 +1783,16 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>        if (nfsd4_copy_is_async(copy)) {
> -               status = nfserrno(-ENOMEM);
>                async_copy = kzalloc(sizeof(struct nfsd4_copy), GFP_KERNEL);
>                if (!async_copy)
>                        goto out_err;
> 
> This is wrong. Status is success from previous code, and you are now
> returning it in case of error.

This "status =" line was removed because the out_err: label
unconditionally sets status = nfserr_jukebox.


> (Also, the atomic dance does not work. It will not allow desired
> concurency in case of races. Semaphore is canonical solution for
> this.)

I'm not certain which "atomic dance" you are referring to here.
Do you mean:

1792                 if (atomic_inc_return(&nn->pending_async_copies) >
1793                                 (int)rqstp->rq_pool->sp_nrthreads)
1794                         goto out_err;

The cap doesn't have to be perfect; it just has to make sure
that the pending value doesn't underflow or overflow. Note
that this code is updated in a later patch.

Naturally we have to address any issues in upstream first, so
please report issues and propose changes to
linux-nfs@xxxxxxxxxxxxxxx <mailto:linux-nfs@xxxxxxxxxxxxxxx> . Thanks for the review!

--
Chuck Lever