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Subject: Re: [PATCH -next v2] NFSD: Fix error return code in
 nfsd4_interssc_connect()
To:     "J. Bruce Fields" <bfields@fieldses.org>,
        Wei Yongjun <weiyongjun1@huawei.com>
Cc:     Chuck Lever <chuck.lever@oracle.com>, linux-nfs@vger.kernel.org,
        kernel-janitors@vger.kernel.org, Hulk Robot <hulkci@huawei.com>
References: <20210604101237.1661615-1-weiyongjun1@huawei.com>
 <20210604144019.GC24620@fieldses.org>
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On 6/4/21 7:40 AM, J. Bruce Fields wrote:
> On Fri, Jun 04, 2021 at 10:12:37AM +0000, Wei Yongjun wrote:
>> 'status' has been overwritten to 0 after nfsd4_ssc_setup_dul(), this
>> cause 0 will be return in vfs_kern_mount() error case. Fix to return
>> nfserr_nodev in this error.
> Why is that the right error?

That was the original error before it was overwritten by
nfsd4_ssc_setup_dul. However, it actually does not matter which
error nfsd4_interssc_connect returns to caller since nfsd4_copy
maps all errors to nfserr_offload_denied before returning it
to the client.

-Dai

> I don't see it mentioned among the errors
> COPY can return:
>
> 	https://urldefense.com/v3/__https://datatracker.ietf.org/doc/html/rfc7862*page-50__;Iw!!GqivPVa7Brio!NSHjr5li4vkJl0VAWWz2mrW2wiVn9wcJfK7ZJON3bmM8REVUqI82bS4FFQdajQ$
>
> It might be reasonable to just map the error returned by vfs_kern_mount
> to an nfs error, I don't know--we'd need to think about the different
> errors vfs_kern_mount might return.
>
> OFFLOAD_DENIED seems safe as it should cause a fallback to a normal
> copy.
>
> Same goes for the other spot here where we return nodev.
>
> --b.
>
>> Fixes: f4e44b393389 ("NFSD: delay unmount source's export after inter-server copy completed.")
>> Reported-by: Hulk Robot <hulkci@huawei.com>
>> Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
>> ---
>> v1 -> v2: change to return nfserr_nodev
>> ---
>>   fs/nfsd/nfs4proc.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
>> index 0bd71c6da81d..b082cbde3e07 100644
>> --- a/fs/nfsd/nfs4proc.c
>> +++ b/fs/nfsd/nfs4proc.c
>> @@ -1323,6 +1323,7 @@ nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
>>   	ss_mnt = vfs_kern_mount(type, SB_KERNMOUNT, dev_name, raw_data);
>>   	module_put(type->owner);
>>   	if (IS_ERR(ss_mnt)) {
>> +		status = nfserr_nodev;
>>   		if (work)
>>   			nfsd4_ssc_cancel_dul_work(nn, work);
>>   		goto out_free_devname;