staging: lustre: ptlrpc: Forbid too early NRS policy tunings

Wait for a NRS policy to be fully started before allowing
to apply related tunings, so that all fields are properly
initialized.
Signed-off-by: Henri Doreau <henri.doreau@cea.fr>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6673
Reviewed-on: http://review.whamcloud.com/15104Reviewed-by: Emoly Liu <emoly.liu@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/ptlrpc/nrs.c

@@ -619,6 +619,15 @@ static int nrs_policy_ctl(struct ptlrpc_nrs *nrs, char *name,
 		goto out;
 	}
 
+	/**
+	 * Wait for the policy to be fully started before attempting
+	 * to operate it.
+	 */
+	if (policy->pol_state == NRS_POL_STATE_STARTING) {
+		rc = -EAGAIN;
+		goto out;
+	}
+
 	switch (opc) {
 		/**
 		 * Unknown opcode, pass it down to the policy-specific control