knfsd: fix spurious EINVAL errors on first access of new filesystem

patch ac8587dc in mainline.

The v2/v3 acl code in nfsd is translating any return from fh_verify() to
nfserr_inval.  This is particularly unfortunate in the case of an
nfserr_dropit return, which is an internal error meant to indicate to
callers that this request has been deferred and should just be dropped
pending the results of an upcall to mountd.

Thanks to Roland <devzero@web.de> for bug report and data collection.

Cc: Roland <devzero@web.de>
Acked-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Reviewed-By: NeilBrown <neilb@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

fs/nfsd/nfs2acl.c

@@ -41,7 +41,7 @@ static __be32 nfsacld_proc_getacl(struct svc_rqst * rqstp,
 
 	fh = fh_copy(&resp->fh, &argp->fh);
 	if ((nfserr = fh_verify(rqstp, &resp->fh, 0, MAY_NOP)))
-		RETURN_STATUS(nfserr_inval);
+		RETURN_STATUS(nfserr);
 
 	if (argp->mask & ~(NFS_ACL|NFS_ACLCNT|NFS_DFACL|NFS_DFACLCNT))
 		RETURN_STATUS(nfserr_inval);

fs/nfsd/nfs3acl.c

@@ -37,7 +37,7 @@ static __be32 nfsd3_proc_getacl(struct svc_rqst * rqstp,
 
 	fh = fh_copy(&resp->fh, &argp->fh);
 	if ((nfserr = fh_verify(rqstp, &resp->fh, 0, MAY_NOP)))
-		RETURN_STATUS(nfserr_inval);
+		RETURN_STATUS(nfserr);
 
 	if (argp->mask & ~(NFS_ACL|NFS_ACLCNT|NFS_DFACL|NFS_DFACLCNT))
 		RETURN_STATUS(nfserr_inval);