NFS: Fabricate fscache server index key correctly

When fabricating a server index key for fscache, we should clear the index key
buffer before starting to fill it in, not in the middle.

Reported-by: James Pearson <[e-mail]>
Signed-off-by: David Howells <[e-mail]>
Acked-by: Steve Dickson <[e-mail]>
Signed-off-by: Trond Myklebust <[e-mail]>

fs/nfs/fscache-index.c

···
 	struct nfs_server_key *key = buffer;
 	uint16_t len = sizeof(struct nfs_server_key);
 
+	memset(key, 0, len);
 	key->nfsversion = clp->rpc_ops->version;
 	key->family = clp->cl_addr.ss_family;
-
-	memset(key, 0, len);
 
 	switch (clp->cl_addr.ss_family) {
 	case AF_INET: