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 09:36:58AM -0700, dai.ngo@oracle.com wrote:
> 
> 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.

OK, I overlooked that.--b.

> 
> -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;