Re: [PATCH -next v2] NFSD: Fix error return code in nfsd4_interssc_connect()

["J. Bruce Fields" <bfields@fieldses.org>]

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?  I don't see it mentioned among the errors
COPY can return:

	https://datatracker.ietf.org/doc/html/rfc7862#page-50

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;