text: /*
   * GPL HEADER START
   *
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 only,
   * as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License version 2 for more details (a copy is included
   * in the LICENSE file that accompanied this code).
   *
   * You should have received a copy of the GNU General Public License
   * version 2 along with this program; If not, see
   * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
   *
   * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
   * CA 95054 USA or visit www.sun.com if you need additional information or
   * have any questions.
   *
   * GPL HEADER END
   */
  /*
   * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
   * Use is subject to license terms.
   *
   * Copyright (c) 2011, 2012, Intel Corporation.
   */
  /*
   * This file is part of Lustre, http://www.lustre.org/
   * Lustre is a trademark of Sun Microsystems, Inc.
   *
   * lustre/mgc/mgc_request.c
   *
   * Author: Nathan Rutman <nathan@clusterfs.com>
   */
  
  #define DEBUG_SUBSYSTEM S_MGC
  #define D_MGC D_CONFIG /*|D_WARNING*/
  
  #include <linux/module.h>
  #include <obd_class.h>
  #include <lustre_dlm.h>
  #include <lprocfs_status.h>
  #include <lustre_log.h>
  #include <lustre_disk.h>
  #include <dt_object.h>
  
  #include "mgc_internal.h"
  
  static int mgc_name2resid(char *name, int len, struct ldlm_res_id *res_id,
  			  int type)
  {
  	__u64 resname = 0;
  
  	if (len > sizeof(resname)) {
  		CERROR("name too long: %s\n", name);
  		return -EINVAL;
  	}
  	if (len <= 0) {
  		CERROR("missing name: %s\n", name);
  		return -EINVAL;
  	}
  	memcpy(&resname, name, len);
  
  	/* Always use the same endianness for the resid */
  	memset(res_id, 0, sizeof(*res_id));
  	res_id->name[0] = cpu_to_le64(resname);
  	/* XXX: unfortunately, sptlprc and config llog share one lock */
  	switch (type) {
  	case CONFIG_T_CONFIG:
  	case CONFIG_T_SPTLRPC:
  		resname = 0;
  		break;
  	case CONFIG_T_RECOVER:
  	case CONFIG_T_PARAMS:
  		resname = type;
  		break;
  	default:
  		LBUG();
  	}
  	res_id->name[1] = cpu_to_le64(resname);
  	CDEBUG(D_MGC, "log %s to resid "LPX64"/"LPX64" (%.8s)\n", name,
  	       res_id->name[0], res_id->name[1], (char *)&res_id->name[0]);
  	return 0;
  }
  
  int mgc_fsname2resid(char *fsname, struct ldlm_res_id *res_id, int type)
  {
  	/* fsname is at most 8 chars long, maybe contain "-".
  	 * e.g. "lustre", "SUN-000" */
  	return mgc_name2resid(fsname, strlen(fsname), res_id, type);
  }
  EXPORT_SYMBOL(mgc_fsname2resid);
  
  int mgc_logname2resid(char *logname, struct ldlm_res_id *res_id, int type)
  {
  	char *name_end;
  	int len;
  
  	/* logname consists of "fsname-nodetype".
  	 * e.g. "lustre-MDT0001", "SUN-000-client"
  	 * there is an exception: llog "params" */
  	name_end = strrchr(logname, '-');
  	if (!name_end)
  		len = strlen(logname);
  	else
  		len = name_end - logname;
  	return mgc_name2resid(logname, len, res_id, type);
  }
  
  /********************** config llog list **********************/
  static LIST_HEAD(config_llog_list);
  static DEFINE_SPINLOCK(config_list_lock);
  
  /* Take a reference to a config log */
  static int config_log_get(struct config_llog_data *cld)
  {
  	atomic_inc(&cld->cld_refcount);
  	CDEBUG(D_INFO, "log %s refs %d\n", cld->cld_logname,
  	       atomic_read(&cld->cld_refcount));
  	return 0;
  }
  
  /* Drop a reference to a config log.  When no longer referenced,
     we can free the config log data */
  static void config_log_put(struct config_llog_data *cld)
  {
  	CDEBUG(D_INFO, "log %s refs %d\n", cld->cld_logname,
  	       atomic_read(&cld->cld_refcount));
  	LASSERT(atomic_read(&cld->cld_refcount) > 0);
  
  	/* spinlock to make sure no item with 0 refcount in the list */
  	if (atomic_dec_and_lock(&cld->cld_refcount, &config_list_lock)) {
  		list_del(&cld->cld_list_chain);
  		spin_unlock(&config_list_lock);
  
  		CDEBUG(D_MGC, "dropping config log %s\n", cld->cld_logname);
  
  		if (cld->cld_recover)
  			config_log_put(cld->cld_recover);
  		if (cld->cld_sptlrpc)
  			config_log_put(cld->cld_sptlrpc);
  		if (cld->cld_params)
  			config_log_put(cld->cld_params);
  		if (cld_is_sptlrpc(cld))
  			sptlrpc_conf_log_stop(cld->cld_logname);
  
  		class_export_put(cld->cld_mgcexp);
  		OBD_FREE(cld, sizeof(*cld) + strlen(cld->cld_logname) + 1);
  	}
  }
  
  /* Find a config log by name */
  static
  struct config_llog_data *config_log_find(char *logname,
  					 struct config_llog_instance *cfg)
  {
  	struct config_llog_data *cld;
  	struct config_llog_data *found = NULL;
  	void *		   instance;
  
  	LASSERT(logname != NULL);
  
  	instance = cfg ? cfg->cfg_instance : NULL;
  	spin_lock(&config_list_lock);
  	list_for_each_entry(cld, &config_llog_list, cld_list_chain) {
  		/* check if instance equals */
  		if (instance != cld->cld_cfg.cfg_instance)
  			continue;
  
  		/* instance may be NULL, should check name */
  		if (strcmp(logname, cld->cld_logname) == 0) {
  			found = cld;
  			break;
  		}
  	}
  	if (found) {
  		atomic_inc(&found->cld_refcount);
  		LASSERT(found->cld_stopping == 0 || cld_is_sptlrpc(found) == 0);
  	}
  	spin_unlock(&config_list_lock);
  	return found;
  }
  
  static
  struct config_llog_data *do_config_log_add(struct obd_device *obd,
  					   char *logname,
  					   int type,
  					   struct config_llog_instance *cfg,
  					   struct super_block *sb)
  {
  	struct config_llog_data *cld;
  	int		      rc;
  
  	CDEBUG(D_MGC, "do adding config log %s:%p\n", logname,
  	       cfg ? cfg->cfg_instance : 0);
  
  	OBD_ALLOC(cld, sizeof(*cld) + strlen(logname) + 1);
  	if (!cld)
  		return ERR_PTR(-ENOMEM);
  
  	strcpy(cld->cld_logname, logname);
  	if (cfg)
  		cld->cld_cfg = *cfg;
  	else
  		cld->cld_cfg.cfg_callback = class_config_llog_handler;
  	mutex_init(&cld->cld_lock);
  	cld->cld_cfg.cfg_last_idx = 0;
  	cld->cld_cfg.cfg_flags = 0;
  	cld->cld_cfg.cfg_sb = sb;
  	cld->cld_type = type;
  	atomic_set(&cld->cld_refcount, 1);
  
  	/* Keep the mgc around until we are done */
  	cld->cld_mgcexp = class_export_get(obd->obd_self_export);
  
  	if (cld_is_sptlrpc(cld)) {
  		sptlrpc_conf_log_start(logname);
  		cld->cld_cfg.cfg_obdname = obd->obd_name;
  	}
  
  	rc = mgc_logname2resid(logname, &cld->cld_resid, type);
  
  	spin_lock(&config_list_lock);
  	list_add(&cld->cld_list_chain, &config_llog_list);
  	spin_unlock(&config_list_lock);
  
  	if (rc) {
  		config_log_put(cld);
  		return ERR_PTR(rc);
  	}
  
  	if (cld_is_sptlrpc(cld)) {
  		rc = mgc_process_log(obd, cld);
  		if (rc && rc != -ENOENT)
  			CERROR("failed processing sptlrpc log: %d\n", rc);
  	}
  
  	return cld;
  }
  
  static struct config_llog_data *config_recover_log_add(struct obd_device *obd,
  	char *fsname,
  	struct config_llog_instance *cfg,
  	struct super_block *sb)
  {
  	struct config_llog_instance lcfg = *cfg;
  	struct lustre_sb_info *lsi = s2lsi(sb);
  	struct config_llog_data *cld;
  	char logname[32];
  
  	if (IS_OST(lsi))
  		return NULL;
  
  	/* for osp-on-ost, see lustre_start_osp() */
  	if (IS_MDT(lsi) && lcfg.cfg_instance)
  		return NULL;
  
  	/* we have to use different llog for clients and mdts for cmd
  	 * where only clients are notified if one of cmd server restarts */
  	LASSERT(strlen(fsname) < sizeof(logname) / 2);
  	strcpy(logname, fsname);
  	if (IS_SERVER(lsi)) { /* mdt */
  		LASSERT(lcfg.cfg_instance == NULL);
  		lcfg.cfg_instance = sb;
  		strcat(logname, "-mdtir");
  	} else {
  		LASSERT(lcfg.cfg_instance != NULL);
  		strcat(logname, "-cliir");
  	}
  
  	cld = do_config_log_add(obd, logname, CONFIG_T_RECOVER, &lcfg, sb);
  	return cld;
  }
  
  static struct config_llog_data *config_params_log_add(struct obd_device *obd,
  	struct config_llog_instance *cfg, struct super_block *sb)
  {
  	struct config_llog_instance	lcfg = *cfg;
  	struct config_llog_data		*cld;
  
  	lcfg.cfg_instance = sb;
  
  	cld = do_config_log_add(obd, PARAMS_FILENAME, CONFIG_T_PARAMS,
  				&lcfg, sb);
  
  	return cld;
  }
  
  /** Add this log to the list of active logs watched by an MGC.
   * Active means we're watching for updates.
   * We have one active log per "mount" - client instance or servername.
   * Each instance may be at a different point in the log.
   */
  static int config_log_add(struct obd_device *obd, char *logname,
  			  struct config_llog_instance *cfg,
  			  struct super_block *sb)
  {
  	struct lustre_sb_info *lsi = s2lsi(sb);
  	struct config_llog_data *cld;
  	struct config_llog_data *sptlrpc_cld;
  	struct config_llog_data *params_cld;
  	char			seclogname[32];
  	char			*ptr;
  	int			rc;
  
  	CDEBUG(D_MGC, "adding config log %s:%p\n", logname, cfg->cfg_instance);
  
  	/*
  	 * for each regular log, the depended sptlrpc log name is
  	 * <fsname>-sptlrpc. multiple regular logs may share one sptlrpc log.
  	 */
  	ptr = strrchr(logname, '-');
  	if (ptr == NULL || ptr - logname > 8) {
  		CERROR("logname %s is too long\n", logname);
  		return -EINVAL;
  	}
  
  	memcpy(seclogname, logname, ptr - logname);
  	strcpy(seclogname + (ptr - logname), "-sptlrpc");
  
  	sptlrpc_cld = config_log_find(seclogname, NULL);
  	if (sptlrpc_cld == NULL) {
  		sptlrpc_cld = do_config_log_add(obd, seclogname,
  						CONFIG_T_SPTLRPC, NULL, NULL);
  		if (IS_ERR(sptlrpc_cld)) {
  			CERROR("can't create sptlrpc log: %s\n", seclogname);
  			GOTO(out_err, rc = PTR_ERR(sptlrpc_cld));
  		}
  	}
  	params_cld = config_params_log_add(obd, cfg, sb);
  	if (IS_ERR(params_cld)) {
  		rc = PTR_ERR(params_cld);
  		CERROR("%s: can't create params log: rc = %d\n",
  		       obd->obd_name, rc);
  		GOTO(out_err1, rc);
  	}
  
  	cld = do_config_log_add(obd, logname, CONFIG_T_CONFIG, cfg, sb);
  	if (IS_ERR(cld)) {
  		CERROR("can't create log: %s\n", logname);
  		GOTO(out_err2, rc = PTR_ERR(cld));
  	}
  
  	cld->cld_sptlrpc = sptlrpc_cld;
  	cld->cld_params = params_cld;
  
  	LASSERT(lsi->lsi_lmd);
  	if (!(lsi->lsi_lmd->lmd_flags & LMD_FLG_NOIR)) {
  		struct config_llog_data *recover_cld;
  		*strrchr(seclogname, '-') = 0;
  		recover_cld = config_recover_log_add(obd, seclogname, cfg, sb);
  		if (IS_ERR(recover_cld))
  			GOTO(out_err3, rc = PTR_ERR(recover_cld));
  		cld->cld_recover = recover_cld;
  	}
  
  	return 0;
  
  out_err3:
  	config_log_put(cld);
  
  out_err2:
  	config_log_put(params_cld);
  
  out_err1:
  	config_log_put(sptlrpc_cld);
  
  out_err:
  	return rc;
  }
  
  DEFINE_MUTEX(llog_process_lock);
  
  /** Stop watching for updates on this log.
   */
  static int config_log_end(char *logname, struct config_llog_instance *cfg)
  {
  	struct config_llog_data *cld;
  	struct config_llog_data *cld_sptlrpc = NULL;
  	struct config_llog_data *cld_params = NULL;
  	struct config_llog_data *cld_recover = NULL;
  	int rc = 0;
  
  	cld = config_log_find(logname, cfg);
  	if (cld == NULL)
  		return -ENOENT;
  
  	mutex_lock(&cld->cld_lock);
  	/*
  	 * if cld_stopping is set, it means we didn't start the log thus
  	 * not owning the start ref. this can happen after previous umount:
  	 * the cld still hanging there waiting for lock cancel, and we
  	 * remount again but failed in the middle and call log_end without
  	 * calling start_log.
  	 */
  	if (unlikely(cld->cld_stopping)) {
  		mutex_unlock(&cld->cld_lock);
  		/* drop the ref from the find */
  		config_log_put(cld);
  		return rc;
  	}
  
  	cld->cld_stopping = 1;
  
  	cld_recover = cld->cld_recover;
  	cld->cld_recover = NULL;
  	mutex_unlock(&cld->cld_lock);
  
  	if (cld_recover) {
  		mutex_lock(&cld_recover->cld_lock);
  		cld_recover->cld_stopping = 1;
  		mutex_unlock(&cld_recover->cld_lock);
  		config_log_put(cld_recover);
  	}
  
  	spin_lock(&config_list_lock);
  	cld_sptlrpc = cld->cld_sptlrpc;
  	cld->cld_sptlrpc = NULL;
  	cld_params = cld->cld_params;
  	cld->cld_params = NULL;
  	spin_unlock(&config_list_lock);
  
  	if (cld_sptlrpc)
  		config_log_put(cld_sptlrpc);
  
  	if (cld_params) {
  		mutex_lock(&cld_params->cld_lock);
  		cld_params->cld_stopping = 1;
  		mutex_unlock(&cld_params->cld_lock);
  		config_log_put(cld_params);
  	}
  
  	/* drop the ref from the find */
  	config_log_put(cld);
  	/* drop the start ref */
  	config_log_put(cld);
  
  	CDEBUG(D_MGC, "end config log %s (%d)\n", logname ? logname : "client",
  	       rc);
  	return rc;
  }
  
  #ifdef LPROCFS
  int lprocfs_mgc_rd_ir_state(struct seq_file *m, void *data)
  {
  	struct obd_device       *obd = data;
  	struct obd_import       *imp = obd->u.cli.cl_import;
  	struct obd_connect_data *ocd = &imp->imp_connect_data;
  	struct config_llog_data *cld;
  
  	seq_printf(m, "imperative_recovery: %s\n",
  		      OCD_HAS_FLAG(ocd, IMP_RECOV) ? "ENABLED" : "DISABLED");
  	seq_printf(m, "client_state:\n");
  
  	spin_lock(&config_list_lock);
  	list_for_each_entry(cld, &config_llog_list, cld_list_chain) {
  		if (cld->cld_recover == NULL)
  			continue;
  		seq_printf(m,  "    - { client: %s, nidtbl_version: %u }\n",
  			       cld->cld_logname,
  			       cld->cld_recover->cld_cfg.cfg_last_idx);
  	}
  	spin_unlock(&config_list_lock);
  
  	return 0;
  }
  #endif
  
  /* reenqueue any lost locks */
  #define RQ_RUNNING 0x1
  #define RQ_NOW     0x2
  #define RQ_LATER   0x4
  #define RQ_STOP    0x8
  static int		    rq_state = 0;
  static wait_queue_head_t	    rq_waitq;
  static DECLARE_COMPLETION(rq_exit);
  
  static void do_requeue(struct config_llog_data *cld)
  {
  	LASSERT(atomic_read(&cld->cld_refcount) > 0);
  
  	/* Do not run mgc_process_log on a disconnected export or an
  	   export which is being disconnected. Take the client
  	   semaphore to make the check non-racy. */
  	down_read(&cld->cld_mgcexp->exp_obd->u.cli.cl_sem);
  	if (cld->cld_mgcexp->exp_obd->u.cli.cl_conn_count != 0) {
  		CDEBUG(D_MGC, "updating log %s\n", cld->cld_logname);
  		mgc_process_log(cld->cld_mgcexp->exp_obd, cld);
  	} else {
  		CDEBUG(D_MGC, "disconnecting, won't update log %s\n",
  		       cld->cld_logname);
  	}
  	up_read(&cld->cld_mgcexp->exp_obd->u.cli.cl_sem);
  }
  
  /* this timeout represents how many seconds MGC should wait before
   * requeue config and recover lock to the MGS. We need to randomize this
   * in order to not flood the MGS.
   */
  #define MGC_TIMEOUT_MIN_SECONDS   5
  #define MGC_TIMEOUT_RAND_CENTISEC 0x1ff /* ~500 */
  
  static int mgc_requeue_thread(void *data)
  {
  	int rc = 0;
  
  	CDEBUG(D_MGC, "Starting requeue thread\n");
  
  	/* Keep trying failed locks periodically */
  	spin_lock(&config_list_lock);
  	rq_state |= RQ_RUNNING;
  	while (1) {
  		struct l_wait_info lwi;
  		struct config_llog_data *cld, *cld_prev;
  		int rand = cfs_rand() & MGC_TIMEOUT_RAND_CENTISEC;
  		int stopped = !!(rq_state & RQ_STOP);
  		int to;
  
  		/* Any new or requeued lostlocks will change the state */
  		rq_state &= ~(RQ_NOW | RQ_LATER);
  		spin_unlock(&config_list_lock);
  
  		/* Always wait a few seconds to allow the server who
  		   caused the lock revocation to finish its setup, plus some
  		   random so everyone doesn't try to reconnect at once. */
  		to = MGC_TIMEOUT_MIN_SECONDS * HZ;
  		to += rand * HZ / 100; /* rand is centi-seconds */
  		lwi = LWI_TIMEOUT(to, NULL, NULL);
  		l_wait_event(rq_waitq, rq_state & RQ_STOP, &lwi);
  
  		/*
  		 * iterate & processing through the list. for each cld, process
  		 * its depending sptlrpc cld firstly (if any) and then itself.
  		 *
  		 * it's guaranteed any item in the list must have
  		 * reference > 0; and if cld_lostlock is set, at
  		 * least one reference is taken by the previous enqueue.
  		 */
  		cld_prev = NULL;
  
  		spin_lock(&config_list_lock);
  		list_for_each_entry(cld, &config_llog_list,
  					cld_list_chain) {
  			if (!cld->cld_lostlock)
  				continue;
  
  			spin_unlock(&config_list_lock);
  
  			LASSERT(atomic_read(&cld->cld_refcount) > 0);
  
  			/* Whether we enqueued again or not in mgc_process_log,
  			 * we're done with the ref from the old enqueue */
  			if (cld_prev)
  				config_log_put(cld_prev);
  			cld_prev = cld;
  
  			cld->cld_lostlock = 0;
  			if (likely(!stopped))
  				do_requeue(cld);
  
  			spin_lock(&config_list_lock);
  		}
  		spin_unlock(&config_list_lock);
  		if (cld_prev)
  			config_log_put(cld_prev);
  
  		/* break after scanning the list so that we can drop
  		 * refcount to losing lock clds */
  		if (unlikely(stopped)) {
  			spin_lock(&config_list_lock);
  			break;
  		}
  
  		/* Wait a bit to see if anyone else needs a requeue */
  		lwi = (struct l_wait_info) { 0 };
  		l_wait_event(rq_waitq, rq_state & (RQ_NOW | RQ_STOP),
  			     &lwi);
  		spin_lock(&config_list_lock);
  	}
  	/* spinlock and while guarantee RQ_NOW and RQ_LATER are not set */
  	rq_state &= ~RQ_RUNNING;
  	spin_unlock(&config_list_lock);
  
  	complete(&rq_exit);
  
  	CDEBUG(D_MGC, "Ending requeue thread\n");
  	return rc;
  }
  
  /* Add a cld to the list to requeue.  Start the requeue thread if needed.
     We are responsible for dropping the config log reference from here on out. */
  static void mgc_requeue_add(struct config_llog_data *cld)
  {
  	CDEBUG(D_INFO, "log %s: requeue (r=%d sp=%d st=%x)\n",
  	       cld->cld_logname, atomic_read(&cld->cld_refcount),
  	       cld->cld_stopping, rq_state);
  	LASSERT(atomic_read(&cld->cld_refcount) > 0);
  
  	mutex_lock(&cld->cld_lock);
  	if (cld->cld_stopping || cld->cld_lostlock) {
  		mutex_unlock(&cld->cld_lock);
  		return;
  	}
  	/* this refcount will be released in mgc_requeue_thread. */
  	config_log_get(cld);
  	cld->cld_lostlock = 1;
  	mutex_unlock(&cld->cld_lock);
  
  	/* Hold lock for rq_state */
  	spin_lock(&config_list_lock);
  	if (rq_state & RQ_STOP) {
  		spin_unlock(&config_list_lock);
  		cld->cld_lostlock = 0;
  		config_log_put(cld);
  	} else {
  		rq_state |= RQ_NOW;
  		spin_unlock(&config_list_lock);
  		wake_up(&rq_waitq);
  	}
  }
  
  /********************** class fns **********************/
  static int mgc_local_llog_init(const struct lu_env *env,
  			       struct obd_device *obd,
  			       struct obd_device *disk)
  {
  	struct llog_ctxt	*ctxt;
  	int			 rc;
  
  	rc = llog_setup(env, obd, &obd->obd_olg, LLOG_CONFIG_ORIG_CTXT, disk,
  			&llog_osd_ops);
  	if (rc)
  		return rc;
  
  	ctxt = llog_get_context(obd, LLOG_CONFIG_ORIG_CTXT);
  	LASSERT(ctxt);
  	ctxt->loc_dir = obd->u.cli.cl_mgc_configs_dir;
  	llog_ctxt_put(ctxt);
  
  	return 0;
  }
  
  static int mgc_local_llog_fini(const struct lu_env *env,
  			       struct obd_device *obd)
  {
  	struct llog_ctxt *ctxt;
  
  	ctxt = llog_get_context(obd, LLOG_CONFIG_ORIG_CTXT);
  	llog_cleanup(env, ctxt);
  
  	return 0;
  }
  
  static int mgc_fs_setup(struct obd_device *obd, struct super_block *sb)
  {
  	struct lustre_sb_info	*lsi = s2lsi(sb);
  	struct client_obd	*cli = &obd->u.cli;
  	struct lu_fid		 rfid, fid;
  	struct dt_object	*root, *dto;
  	struct lu_env		*env;
  	int			 rc = 0;
  
  	LASSERT(lsi);
  	LASSERT(lsi->lsi_dt_dev);
  
  	OBD_ALLOC_PTR(env);
  	if (env == NULL)
  		return -ENOMEM;
  
  	/* The mgc fs exclusion mutex. Only one fs can be setup at a time. */
  	mutex_lock(&cli->cl_mgc_mutex);
  
  	cfs_cleanup_group_info();
  
  	/* Setup the configs dir */
  	rc = lu_env_init(env, LCT_MG_THREAD);
  	if (rc)
  		GOTO(out_err, rc);
  
  	fid.f_seq = FID_SEQ_LOCAL_NAME;
  	fid.f_oid = 1;
  	fid.f_ver = 0;
  	rc = local_oid_storage_init(env, lsi->lsi_dt_dev, &fid,
  				    &cli->cl_mgc_los);
  	if (rc)
  		GOTO(out_env, rc);
  
  	rc = dt_root_get(env, lsi->lsi_dt_dev, &rfid);
  	if (rc)
  		GOTO(out_env, rc);
  
  	root = dt_locate_at(env, lsi->lsi_dt_dev, &rfid,
  			    &cli->cl_mgc_los->los_dev->dd_lu_dev);
  	if (unlikely(IS_ERR(root)))
  		GOTO(out_los, rc = PTR_ERR(root));
  
  	dto = local_file_find_or_create(env, cli->cl_mgc_los, root,
  					MOUNT_CONFIGS_DIR,
  					S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO);
  	lu_object_put_nocache(env, &root->do_lu);
  	if (IS_ERR(dto))
  		GOTO(out_los, rc = PTR_ERR(dto));
  
  	cli->cl_mgc_configs_dir = dto;
  
  	LASSERT(lsi->lsi_osd_exp->exp_obd->obd_lvfs_ctxt.dt);
  	rc = mgc_local_llog_init(env, obd, lsi->lsi_osd_exp->exp_obd);
  	if (rc)
  		GOTO(out_llog, rc);
  
  	/* We take an obd ref to insure that we can't get to mgc_cleanup
  	 * without calling mgc_fs_cleanup first. */
  	class_incref(obd, "mgc_fs", obd);
  
  	/* We keep the cl_mgc_sem until mgc_fs_cleanup */
  out_llog:
  	if (rc) {
  		lu_object_put(env, &cli->cl_mgc_configs_dir->do_lu);
  		cli->cl_mgc_configs_dir = NULL;
  	}
  out_los:
  	if (rc < 0) {
  		local_oid_storage_fini(env, cli->cl_mgc_los);
  		cli->cl_mgc_los = NULL;
  		mutex_unlock(&cli->cl_mgc_mutex);
  	}
  out_env:
  	lu_env_fini(env);
  out_err:
  	OBD_FREE_PTR(env);
  	return rc;
  }
  
  static int mgc_fs_cleanup(struct obd_device *obd)
  {
  	struct lu_env		 env;
  	struct client_obd	*cli = &obd->u.cli;
  	int			 rc;
  
  	LASSERT(cli->cl_mgc_los != NULL);
  
  	rc = lu_env_init(&env, LCT_MG_THREAD);
  	if (rc)
  		GOTO(unlock, rc);
  
  	mgc_local_llog_fini(&env, obd);
  
  	lu_object_put_nocache(&env, &cli->cl_mgc_configs_dir->do_lu);
  	cli->cl_mgc_configs_dir = NULL;
  
  	local_oid_storage_fini(&env, cli->cl_mgc_los);
  	cli->cl_mgc_los = NULL;
  	lu_env_fini(&env);
  
  unlock:
  	class_decref(obd, "mgc_fs", obd);
  	mutex_unlock(&cli->cl_mgc_mutex);
  
  	return 0;
  }
  
  static int mgc_llog_init(const struct lu_env *env, struct obd_device *obd)
  {
  	struct llog_ctxt	*ctxt;
  	int			 rc;
  
  	/* setup only remote ctxt, the local disk context is switched per each
  	 * filesystem during mgc_fs_setup() */
  	rc = llog_setup(env, obd, &obd->obd_olg, LLOG_CONFIG_REPL_CTXT, obd,
  			&llog_client_ops);
  	if (rc)
  		return rc;
  
  	ctxt = llog_get_context(obd, LLOG_CONFIG_REPL_CTXT);
  	LASSERT(ctxt);
  
  	llog_initiator_connect(ctxt);
  	llog_ctxt_put(ctxt);
  
  	return 0;
  }
  
  static int mgc_llog_fini(const struct lu_env *env, struct obd_device *obd)
  {
  	struct llog_ctxt *ctxt;
  
  	ctxt = llog_get_context(obd, LLOG_CONFIG_REPL_CTXT);
  	if (ctxt)
  		llog_cleanup(env, ctxt);
  
  	return 0;
  }
  
  static atomic_t mgc_count = ATOMIC_INIT(0);
  static int mgc_precleanup(struct obd_device *obd, enum obd_cleanup_stage stage)
  {
  	int rc = 0;
  
  	switch (stage) {
  	case OBD_CLEANUP_EARLY:
  		break;
  	case OBD_CLEANUP_EXPORTS:
  		if (atomic_dec_and_test(&mgc_count)) {
  			int running;
  			/* stop requeue thread */
  			spin_lock(&config_list_lock);
  			running = rq_state & RQ_RUNNING;
  			if (running)
  				rq_state |= RQ_STOP;
  			spin_unlock(&config_list_lock);
  			if (running) {
  				wake_up(&rq_waitq);
  				wait_for_completion(&rq_exit);
  			}
  		}
  		obd_cleanup_client_import(obd);
  		rc = mgc_llog_fini(NULL, obd);
  		if (rc != 0)
  			CERROR("failed to cleanup llogging subsystems\n");
  		break;
  	}
  	return rc;
  }
  
  static int mgc_cleanup(struct obd_device *obd)
  {
  	int rc;
  
  	/* COMPAT_146 - old config logs may have added profiles we don't
  	   know about */
  	if (obd->obd_type->typ_refcnt <= 1)
  		/* Only for the last mgc */
  		class_del_profiles();
  
  	lprocfs_obd_cleanup(obd);
  	ptlrpcd_decref();
  
  	rc = client_obd_cleanup(obd);
  	return rc;
  }
  
  static int mgc_setup(struct obd_device *obd, struct lustre_cfg *lcfg)
  {
  	struct lprocfs_static_vars lvars;
  	int rc;
  
  	ptlrpcd_addref();
  
  	rc = client_obd_setup(obd, lcfg);
  	if (rc)
  		GOTO(err_decref, rc);
  
  	rc = mgc_llog_init(NULL, obd);
  	if (rc) {
  		CERROR("failed to setup llogging subsystems\n");
  		GOTO(err_cleanup, rc);
  	}
  
  	lprocfs_mgc_init_vars(&lvars);
  	lprocfs_obd_setup(obd, lvars.obd_vars);
  	sptlrpc_lprocfs_cliobd_attach(obd);
  
  	if (atomic_inc_return(&mgc_count) == 1) {
  		rq_state = 0;
  		init_waitqueue_head(&rq_waitq);
  
  		/* start requeue thread */
  		rc = PTR_ERR(kthread_run(mgc_requeue_thread, NULL,
  					     "ll_cfg_requeue"));
  		if (IS_ERR_VALUE(rc)) {
  			CERROR("%s: Cannot start requeue thread (%d),"
  			       "no more log updates!\n",
  			       obd->obd_name, rc);
  			GOTO(err_cleanup, rc);
  		}
  		/* rc is the task_struct pointer of mgc_requeue_thread. */
  		rc = 0;
  	}
  
  	return rc;
  
  err_cleanup:
  	client_obd_cleanup(obd);
  err_decref:
  	ptlrpcd_decref();
  	return rc;
  }
  
  /* based on ll_mdc_blocking_ast */
  static int mgc_blocking_ast(struct ldlm_lock *lock, struct ldlm_lock_desc *desc,
  			    void *data, int flag)
  {
  	struct lustre_handle lockh;
  	struct config_llog_data *cld = (struct config_llog_data *)data;
  	int rc = 0;
  
  	switch (flag) {
  	case LDLM_CB_BLOCKING:
  		/* mgs wants the lock, give it up... */
  		LDLM_DEBUG(lock, "MGC blocking CB");
  		ldlm_lock2handle(lock, &lockh);
  		rc = ldlm_cli_cancel(&lockh, LCF_ASYNC);
  		break;
  	case LDLM_CB_CANCELING:
  		/* We've given up the lock, prepare ourselves to update. */
  		LDLM_DEBUG(lock, "MGC cancel CB");
  
  		CDEBUG(D_MGC, "Lock res "DLDLMRES" (%.8s)\n",
  		       PLDLMRES(lock->l_resource),
  		       (char *)&lock->l_resource->lr_name.name[0]);
  
  		if (!cld) {
  			CDEBUG(D_INFO, "missing data, won't requeue\n");
  			break;
  		}
  
  		/* held at mgc_process_log(). */
  		LASSERT(atomic_read(&cld->cld_refcount) > 0);
  		/* Are we done with this log? */
  		if (cld->cld_stopping) {
  			CDEBUG(D_MGC, "log %s: stopping, won't requeue\n",
  			       cld->cld_logname);
  			config_log_put(cld);
  			break;
  		}
  		/* Make sure not to re-enqueue when the mgc is stopping
  		   (we get called from client_disconnect_export) */
  		if (!lock->l_conn_export ||
  		    !lock->l_conn_export->exp_obd->u.cli.cl_conn_count) {
  			CDEBUG(D_MGC, "log %.8s: disconnecting, won't requeue\n",
  			       cld->cld_logname);
  			config_log_put(cld);
  			break;
  		}
  
  		/* Re-enqueue now */
  		mgc_requeue_add(cld);
  		config_log_put(cld);
  		break;
  	default:
  		LBUG();
  	}
  
  	return rc;
  }
  
  /* Not sure where this should go... */
  #define  MGC_ENQUEUE_LIMIT 50
  #define  MGC_TARGET_REG_LIMIT 10
  #define  MGC_SEND_PARAM_LIMIT 10
  
  /* Send parameter to MGS*/
  static int mgc_set_mgs_param(struct obd_export *exp,
  			     struct mgs_send_param *msp)
  {
  	struct ptlrpc_request *req;
  	struct mgs_send_param *req_msp, *rep_msp;
  	int rc;
  
  	req = ptlrpc_request_alloc_pack(class_exp2cliimp(exp),
  					&RQF_MGS_SET_INFO, LUSTRE_MGS_VERSION,
  					MGS_SET_INFO);
  	if (!req)
  		return -ENOMEM;
  
  	req_msp = req_capsule_client_get(&req->rq_pill, &RMF_MGS_SEND_PARAM);
  	if (!req_msp) {
  		ptlrpc_req_finished(req);
  		return -ENOMEM;
  	}
  
  	memcpy(req_msp, msp, sizeof(*req_msp));
  	ptlrpc_request_set_replen(req);
  
  	/* Limit how long we will wait for the enqueue to complete */
  	req->rq_delay_limit = MGC_SEND_PARAM_LIMIT;
  	rc = ptlrpc_queue_wait(req);
  	if (!rc) {
  		rep_msp = req_capsule_server_get(&req->rq_pill, &RMF_MGS_SEND_PARAM);
  		memcpy(msp, rep_msp, sizeof(*rep_msp));
  	}
  
  	ptlrpc_req_finished(req);
  
  	return rc;
  }
  
  /* Take a config lock so we can get cancel notifications */
  static int mgc_enqueue(struct obd_export *exp, struct lov_stripe_md *lsm,
  		       __u32 type, ldlm_policy_data_t *policy, __u32 mode,
  		       __u64 *flags, void *bl_cb, void *cp_cb, void *gl_cb,
  		       void *data, __u32 lvb_len, void *lvb_swabber,
  		       struct lustre_handle *lockh)
  {
  	struct config_llog_data *cld = (struct config_llog_data *)data;
  	struct ldlm_enqueue_info einfo = {
  		.ei_type	= type,
  		.ei_mode	= mode,
  		.ei_cb_bl	= mgc_blocking_ast,
  		.ei_cb_cp	= ldlm_completion_ast,
  	};
  	struct ptlrpc_request *req;
  	int short_limit = cld_is_sptlrpc(cld);
  	int rc;
  
  	CDEBUG(D_MGC, "Enqueue for %s (res "LPX64")\n", cld->cld_logname,
  	       cld->cld_resid.name[0]);
  
  	/* We need a callback for every lockholder, so don't try to
  	   ldlm_lock_match (see rev 1.1.2.11.2.47) */
  	req = ptlrpc_request_alloc_pack(class_exp2cliimp(exp),
  					&RQF_LDLM_ENQUEUE, LUSTRE_DLM_VERSION,
  					LDLM_ENQUEUE);
  	if (req == NULL)
  		return -ENOMEM;
  
  	req_capsule_set_size(&req->rq_pill, &RMF_DLM_LVB, RCL_SERVER, 0);
  	ptlrpc_request_set_replen(req);
  
  	/* check if this is server or client */
  	if (cld->cld_cfg.cfg_sb) {
  		struct lustre_sb_info *lsi = s2lsi(cld->cld_cfg.cfg_sb);
  		if (lsi && IS_SERVER(lsi))
  			short_limit = 1;
  	}
  	/* Limit how long we will wait for the enqueue to complete */
  	req->rq_delay_limit = short_limit ? 5 : MGC_ENQUEUE_LIMIT;
  	rc = ldlm_cli_enqueue(exp, &req, &einfo, &cld->cld_resid, NULL, flags,
  			      NULL, 0, LVB_T_NONE, lockh, 0);
  	/* A failed enqueue should still call the mgc_blocking_ast,
  	   where it will be requeued if needed ("grant failed"). */
  	ptlrpc_req_finished(req);
  	return rc;
  }
  
  static int mgc_cancel(struct obd_export *exp, struct lov_stripe_md *md,
  		      __u32 mode, struct lustre_handle *lockh)
  {
  	ldlm_lock_decref(lockh, mode);
  
  	return 0;
  }
  
  static void mgc_notify_active(struct obd_device *unused)
  {
  	/* wakeup mgc_requeue_thread to requeue mgc lock */
  	spin_lock(&config_list_lock);
  	rq_state |= RQ_NOW;
  	spin_unlock(&config_list_lock);
  	wake_up(&rq_waitq);
  
  	/* TODO: Help the MGS rebuild nidtbl. -jay */
  }
  
  /* Send target_reg message to MGS */
  static int mgc_target_register(struct obd_export *exp,
  			       struct mgs_target_info *mti)
  {
  	struct ptlrpc_request  *req;
  	struct mgs_target_info *req_mti, *rep_mti;
  	int		     rc;
  
  	req = ptlrpc_request_alloc_pack(class_exp2cliimp(exp),
  					&RQF_MGS_TARGET_REG, LUSTRE_MGS_VERSION,
  					MGS_TARGET_REG);
  	if (req == NULL)
  		return -ENOMEM;
  
  	req_mti = req_capsule_client_get(&req->rq_pill, &RMF_MGS_TARGET_INFO);
  	if (!req_mti) {
  		ptlrpc_req_finished(req);
  		return -ENOMEM;
  	}
  
  	memcpy(req_mti, mti, sizeof(*req_mti));
  	ptlrpc_request_set_replen(req);
  	CDEBUG(D_MGC, "register %s\n", mti->mti_svname);
  	/* Limit how long we will wait for the enqueue to complete */
  	req->rq_delay_limit = MGC_TARGET_REG_LIMIT;
  
  	rc = ptlrpc_queue_wait(req);
  	if (!rc) {
  		rep_mti = req_capsule_server_get(&req->rq_pill,
  						 &RMF_MGS_TARGET_INFO);
  		memcpy(mti, rep_mti, sizeof(*rep_mti));
  		CDEBUG(D_MGC, "register %s got index = %d\n",
  		       mti->mti_svname, mti->mti_stripe_index);
  	}
  	ptlrpc_req_finished(req);
  
  	return rc;
  }
  
  int mgc_set_info_async(const struct lu_env *env, struct obd_export *exp,
  		       obd_count keylen, void *key, obd_count vallen,
  		       void *val, struct ptlrpc_request_set *set)
  {
  	int rc = -EINVAL;
  
  	/* Turn off initial_recov after we try all backup servers once */
  	if (KEY_IS(KEY_INIT_RECOV_BACKUP)) {
  		struct obd_import *imp = class_exp2cliimp(exp);
  		int value;
  		if (vallen != sizeof(int))
  			return -EINVAL;
  		value = *(int *)val;
  		CDEBUG(D_MGC, "InitRecov %s %d/d%d:i%d:r%d:or%d:%s\n",
  		       imp->imp_obd->obd_name, value,
  		       imp->imp_deactive, imp->imp_invalid,
  		       imp->imp_replayable, imp->imp_obd->obd_replayable,
  		       ptlrpc_import_state_name(imp->imp_state));
  		/* Resurrect if we previously died */
  		if ((imp->imp_state != LUSTRE_IMP_FULL &&
  		     imp->imp_state != LUSTRE_IMP_NEW) || value > 1)
  			ptlrpc_reconnect_import(imp);
  		return 0;
  	}
  	/* FIXME move this to mgc_process_config */
  	if (KEY_IS(KEY_REGISTER_TARGET)) {
  		struct mgs_target_info *mti;
  		if (vallen != sizeof(struct mgs_target_info))
  			return -EINVAL;
  		mti = (struct mgs_target_info *)val;
  		CDEBUG(D_MGC, "register_target %s %#x\n",
  		       mti->mti_svname, mti->mti_flags);
  		rc =  mgc_target_register(exp, mti);
  		return rc;
  	}
  	if (KEY_IS(KEY_SET_FS)) {
  		struct super_block *sb = (struct super_block *)val;
  
  		if (vallen != sizeof(struct super_block))
  			return -EINVAL;
  
  		rc = mgc_fs_setup(exp->exp_obd, sb);
  		if (rc)
  			CERROR("set_fs got %d\n", rc);
  
  		return rc;
  	}
  	if (KEY_IS(KEY_CLEAR_FS)) {
  		if (vallen != 0)
  			return -EINVAL;
  		rc = mgc_fs_cleanup(exp->exp_obd);
  		if (rc)
  			CERROR("clear_fs got %d\n", rc);
  
  		return rc;
  	}
  	if (KEY_IS(KEY_SET_INFO)) {
  		struct mgs_send_param *msp;
  
  		msp = (struct mgs_send_param *)val;
  		rc =  mgc_set_mgs_param(exp, msp);
  		return rc;
  	}
  	if (KEY_IS(KEY_MGSSEC)) {
  		struct client_obd     *cli = &exp->exp_obd->u.cli;
  		struct sptlrpc_flavor  flvr;
  
  		/*
  		 * empty string means using current flavor, if which haven't
  		 * been set yet, set it as null.
  		 *
  		 * if flavor has been set previously, check the asking flavor
  		 * must match the existing one.
  		 */
  		if (vallen == 0) {
  			if (cli->cl_flvr_mgc.sf_rpc != SPTLRPC_FLVR_INVALID)
  				return 0;
  			val = "null";
  			vallen = 4;
  		}
  
  		rc = sptlrpc_parse_flavor(val, &flvr);
  		if (rc) {
  			CERROR("invalid sptlrpc flavor %s to MGS\n",
  			       (char *) val);
  			return rc;
  		}
  
  		/*
  		 * caller already hold a mutex
  		 */
  		if (cli->cl_flvr_mgc.sf_rpc == SPTLRPC_FLVR_INVALID) {
  			cli->cl_flvr_mgc = flvr;
  		} else if (memcmp(&cli->cl_flvr_mgc, &flvr,
  				  sizeof(flvr)) != 0) {
  			char    str[20];
  
  			sptlrpc_flavor2name(&cli->cl_flvr_mgc,
  					    str, sizeof(str));
  			LCONSOLE_ERROR("asking sptlrpc flavor %s to MGS but "
  				       "currently %s is in use\n",
  				       (char *) val, str);
  			rc = -EPERM;
  		}
  		return rc;
  	}
  
  	return rc;
  }
  
  static int mgc_get_info(const struct lu_env *env, struct obd_export *exp,
  			__u32 keylen, void *key, __u32 *vallen, void *val,
  			struct lov_stripe_md *unused)
  {
  	int rc = -EINVAL;
  
  	if (KEY_IS(KEY_CONN_DATA)) {
  		struct obd_import *imp = class_exp2cliimp(exp);
  		struct obd_connect_data *data = val;
  
  		if (*vallen == sizeof(*data)) {
  			*data = imp->imp_connect_data;
  			rc = 0;
  		}
  	}
  
  	return rc;
  }
  
  static int mgc_import_event(struct obd_device *obd,
  			    struct obd_import *imp,
  			    enum obd_import_event event)
  {
  	int rc = 0;
  
  	LASSERT(imp->imp_obd == obd);
  	CDEBUG(D_MGC, "import event %#x\n", event);
  
  	switch (event) {
  	case IMP_EVENT_DISCON:
  		/* MGC imports should not wait for recovery */
  		if (OCD_HAS_FLAG(&imp->imp_connect_data, IMP_RECOV))
  			ptlrpc_pinger_ir_down();
  		break;
  	case IMP_EVENT_INACTIVE:
  		break;
  	case IMP_EVENT_INVALIDATE: {
  		struct ldlm_namespace *ns = obd->obd_namespace;
  		ldlm_namespace_cleanup(ns, LDLM_FL_LOCAL_ONLY);
  		break;
  	}
  	case IMP_EVENT_ACTIVE:
  		CDEBUG(D_INFO, "%s: Reactivating import\n", obd->obd_name);
  		/* Clearing obd_no_recov allows us to continue pinging */
  		obd->obd_no_recov = 0;
  		mgc_notify_active(obd);
  		if (OCD_HAS_FLAG(&imp->imp_connect_data, IMP_RECOV))
  			ptlrpc_pinger_ir_up();
  		break;
  	case IMP_EVENT_OCD:
  		break;
  	case IMP_EVENT_DEACTIVATE:
  	case IMP_EVENT_ACTIVATE:
  		break;
  	default:
  		CERROR("Unknown import event %#x\n", event);
  		LBUG();
  	}
  	return rc;
  }
  
  enum {
  	CONFIG_READ_NRPAGES_INIT = 1 << (20 - PAGE_CACHE_SHIFT),
  	CONFIG_READ_NRPAGES      = 4
  };
  
  static int mgc_apply_recover_logs(struct obd_device *mgc,
  				  struct config_llog_data *cld,
  				  __u64 max_version,
  				  void *data, int datalen, bool mne_swab)
  {
  	struct config_llog_instance *cfg = &cld->cld_cfg;
  	struct lustre_sb_info       *lsi = s2lsi(cfg->cfg_sb);
  	struct mgs_nidtbl_entry *entry;
  	struct lustre_cfg       *lcfg;
  	struct lustre_cfg_bufs   bufs;
  	u64   prev_version = 0;
  	char *inst;
  	char *buf;
  	int   bufsz;
  	int   pos;
  	int   rc  = 0;
  	int   off = 0;
  
  	LASSERT(cfg->cfg_instance != NULL);
  	LASSERT(cfg->cfg_sb == cfg->cfg_instance);
  
  	OBD_ALLOC(inst, PAGE_CACHE_SIZE);
  	if (inst == NULL)
  		return -ENOMEM;
  
  	if (!IS_SERVER(lsi)) {
  		pos = snprintf(inst, PAGE_CACHE_SIZE, "%p", cfg->cfg_instance);
  		if (pos >= PAGE_CACHE_SIZE) {
  			OBD_FREE(inst, PAGE_CACHE_SIZE);
  			return -E2BIG;
  		}
  	} else {
  		LASSERT(IS_MDT(lsi));
  		rc = server_name2svname(lsi->lsi_svname, inst, NULL,
  					PAGE_CACHE_SIZE);
  		if (rc) {
  			OBD_FREE(inst, PAGE_CACHE_SIZE);
  			return -EINVAL;
  		}
  		pos = strlen(inst);
  	}
  
  	++pos;
  	buf   = inst + pos;
  	bufsz = PAGE_CACHE_SIZE - pos;
  
  	while (datalen > 0) {
  		int   entry_len = sizeof(*entry);
  		int   is_ost;
  		struct obd_device *obd;
  		char *obdname;
  		char *cname;
  		char *params;
  		char *uuid;
  
  		rc = -EINVAL;
  		if (datalen < sizeof(*entry))
  			break;
  
  		entry = (typeof(entry))(data + off);
  
  		/* sanity check */
  		if (entry->mne_nid_type != 0) /* only support type 0 for ipv4 */
  			break;
  		if (entry->mne_nid_count == 0) /* at least one nid entry */
  			break;
  		if (entry->mne_nid_size != sizeof(lnet_nid_t))
  			break;
  
  		entry_len += entry->mne_nid_count * entry->mne_nid_size;
  		if (datalen < entry_len) /* must have entry_len at least */
  			break;
  
  		/* Keep this swab for normal mixed endian handling. LU-1644 */
  		if (mne_swab)
  			lustre_swab_mgs_nidtbl_entry(entry);
  		if (entry->mne_length > PAGE_CACHE_SIZE) {
  			CERROR("MNE too large (%u)\n", entry->mne_length);
  			break;
  		}
  
  		if (entry->mne_length < entry_len)
  			break;
  
  		off     += entry->mne_length;
  		datalen -= entry->mne_length;
  		if (datalen < 0)
  			break;
  
  		if (entry->mne_version > max_version) {
  			CERROR("entry index(%lld) is over max_index(%lld)\n",
  			       entry->mne_version, max_version);
  			break;
  		}
  
  		if (prev_version >= entry->mne_version) {
  			CERROR("index unsorted, prev %lld, now %lld\n",
  			       prev_version, entry->mne_version);
  			break;
  		}
  		prev_version = entry->mne_version;
  
  		/*
  		 * Write a string with format "nid::instance" to
  		 * lustre/<osc|mdc>/<target>-<osc|mdc>-<instance>/import.
  		 */
  
  		is_ost = entry->mne_type == LDD_F_SV_TYPE_OST;
  		memset(buf, 0, bufsz);
  		obdname = buf;
  		pos = 0;
  
  		/* lustre-OST0001-osc-<instance #> */
  		strcpy(obdname, cld->cld_logname);
  		cname = strrchr(obdname, '-');
  		if (cname == NULL) {
  			CERROR("mgc %s: invalid logname %s\n",
  			       mgc->obd_name, obdname);
  			break;
  		}
  
  		pos = cname - obdname;
  		obdname[pos] = 0;
  		pos += sprintf(obdname + pos, "-%s%04x",
  				  is_ost ? "OST" : "MDT", entry->mne_index);
  
  		cname = is_ost ? "osc" : "mdc",
  		pos += sprintf(obdname + pos, "-%s-%s", cname, inst);
  		lustre_cfg_bufs_reset(&bufs, obdname);
  
  		/* find the obd by obdname */
  		obd = class_name2obd(obdname);
  		if (obd == NULL) {
  			CDEBUG(D_INFO, "mgc %s: cannot find obdname %s\n",
  			       mgc->obd_name, obdname);
  			rc = 0;
  			/* this is a safe race, when the ost is starting up...*/
  			continue;
  		}
  
  		/* osc.import = "connection=<Conn UUID>::<target instance>" */
  		++pos;
  		params = buf + pos;
  		pos += sprintf(params, "%s.import=%s", cname, "connection=");
  		uuid = buf + pos;
  
  		down_read(&obd->u.cli.cl_sem);
  		if (obd->u.cli.cl_import == NULL) {
  			/* client does not connect to the OST yet */
  			up_read(&obd->u.cli.cl_sem);
  			rc = 0;
  			continue;
  		}
  
  		/* TODO: iterate all nids to find one */
  		/* find uuid by nid */
  		rc = client_import_find_conn(obd->u.cli.cl_import,
  					     entry->u.nids[0],
  					     (struct obd_uuid *)uuid);
  		up_read(&obd->u.cli.cl_sem);
  		if (rc < 0) {
  			CERROR("mgc: cannot find uuid by nid %s\n",
  			       libcfs_nid2str(entry->u.nids[0]));
  			break;
  		}
  
  		CDEBUG(D_INFO, "Find uuid %s by nid %s\n",
  		       uuid, libcfs_nid2str(entry->u.nids[0]));
  
  		pos += strlen(uuid);
  		pos += sprintf(buf + pos, "::%u", entry->mne_instance);
  		LASSERT(pos < bufsz);
  
  		lustre_cfg_bufs_set_string(&bufs, 1, params);
  
  		rc = -ENOMEM;
  		lcfg = lustre_cfg_new(LCFG_PARAM, &bufs);
  		if (lcfg == NULL) {
  			CERROR("mgc: cannot allocate memory\n");
  			break;
  		}
  
  		CDEBUG(D_INFO, "ir apply logs "LPD64"/"LPD64" for %s -> %s\n",
  		       prev_version, max_version, obdname, params);
  
  		rc = class_process_config(lcfg);
  		lustre_cfg_free(lcfg);
  		if (rc)
  			CDEBUG(D_INFO, "process config for %s error %d\n",
  			       obdname, rc);
  
  		/* continue, even one with error */
  	}
  
  	OBD_FREE(inst, PAGE_CACHE_SIZE);
  	return rc;
  }
  
  /**
   * This function is called if this client was notified for target restarting
   * by the MGS. A CONFIG_READ RPC is going to send to fetch recovery logs.
   */
  static int mgc_process_recover_log(struct obd_device *obd,
  				   struct config_llog_data *cld)
  {
  	struct ptlrpc_request *req = NULL;
  	struct config_llog_instance *cfg = &cld->cld_cfg;
  	struct mgs_config_body *body;
  	struct mgs_config_res  *res;
  	struct ptlrpc_bulk_desc *desc;
  	struct page **pages;
  	int nrpages;
  	bool eof = true;
  	bool mne_swab = false;
  	int i;
  	int ealen;
  	int rc;
  
  	/* allocate buffer for bulk transfer.
  	 * if this is the first time for this mgs to read logs,
  	 * CONFIG_READ_NRPAGES_INIT will be used since it will read all logs
  	 * once; otherwise, it only reads increment of logs, this should be
  	 * small and CONFIG_READ_NRPAGES will be used.
  	 */
  	nrpages = CONFIG_READ_NRPAGES;
  	if (cfg->cfg_last_idx == 0) /* the first time */
  		nrpages = CONFIG_READ_NRPAGES_INIT;
  
  	OBD_ALLOC(pages, sizeof(*pages) * nrpages);
  	if (pages == NULL)
  		GOTO(out, rc = -ENOMEM);
  
  	for (i = 0; i < nrpages; i++) {
  		pages[i] = alloc_page(GFP_IOFS);
  		if (pages[i] == NULL)
  			GOTO(out, rc = -ENOMEM);
  	}
  
  again:
  	LASSERT(cld_is_recover(cld));
  	LASSERT(mutex_is_locked(&cld->cld_lock));
  	req = ptlrpc_request_alloc(class_exp2cliimp(cld->cld_mgcexp),
  				   &RQF_MGS_CONFIG_READ);
  	if (req == NULL)
  		GOTO(out, rc = -ENOMEM);
  
  	rc = ptlrpc_request_pack(req, LUSTRE_MGS_VERSION, MGS_CONFIG_READ);
  	if (rc)
  		GOTO(out, rc);
  
  	/* pack request */
  	body = req_capsule_client_get(&req->rq_pill, &RMF_MGS_CONFIG_BODY);
  	LASSERT(body != NULL);
  	LASSERT(sizeof(body->mcb_name) > strlen(cld->cld_logname));
  	if (strlcpy(body->mcb_name, cld->cld_logname, sizeof(body->mcb_name))
  	    >= sizeof(body->mcb_name))
  		GOTO(out, rc = -E2BIG);
  	body->mcb_offset = cfg->cfg_last_idx + 1;
  	body->mcb_type   = cld->cld_type;
  	body->mcb_bits   = PAGE_CACHE_SHIFT;
  	body->mcb_units  = nrpages;
  
  	/* allocate bulk transfer descriptor */
  	desc = ptlrpc_prep_bulk_imp(req, nrpages, 1, BULK_PUT_SINK,
  				    MGS_BULK_PORTAL);
  	if (desc == NULL)
  		GOTO(out, rc = -ENOMEM);
  
  	for (i = 0; i < nrpages; i++)
  		ptlrpc_prep_bulk_page_pin(desc, pages[i], 0, PAGE_CACHE_SIZE);
  
  	ptlrpc_request_set_replen(req);
  	rc = ptlrpc_queue_wait(req);
  	if (rc)
  		GOTO(out, rc);
  
  	res = req_capsule_server_get(&req->rq_pill, &RMF_MGS_CONFIG_RES);
  	if (res->mcr_size < res->mcr_offset)
  		GOTO(out, rc = -EINVAL);
  
  	/* always update the index even though it might have errors with
  	 * handling the recover logs */
  	cfg->cfg_last_idx = res->mcr_offset;
  	eof = res->mcr_offset == res->mcr_size;
  
  	CDEBUG(D_INFO, "Latest version "LPD64", more %d.\n",
  	       res->mcr_offset, eof == false);
  
  	ealen = sptlrpc_cli_unwrap_bulk_read(req, req->rq_bulk, 0);
  	if (ealen < 0)
  		GOTO(out, rc = ealen);
  
  	if (ealen > nrpages << PAGE_CACHE_SHIFT)
  		GOTO(out, rc = -EINVAL);
  
  	if (ealen == 0) { /* no logs transferred */
  		if (!eof)
  			rc = -EINVAL;
  		GOTO(out, rc);
  	}
  
  	mne_swab = !!ptlrpc_rep_need_swab(req);
  #if LUSTRE_VERSION_CODE < OBD_OCD_VERSION(3, 2, 50, 0)
  	/* This import flag means the server did an extra swab of IR MNE
  	 * records (fixed in LU-1252), reverse it here if needed. LU-1644 */
  	if (unlikely(req->rq_import->imp_need_mne_swab))
  		mne_swab = !mne_swab;
  #else
  #warning "LU-1644: Remove old OBD_CONNECT_MNE_SWAB fixup and imp_need_mne_swab"
  #endif
  
  	for (i = 0; i < nrpages && ealen > 0; i++) {
  		int rc2;
  		void *ptr;
  
  		ptr = kmap(pages[i]);
  		rc2 = mgc_apply_recover_logs(obd, cld, res->mcr_offset, ptr,
  					     min_t(int, ealen, PAGE_CACHE_SIZE),
  					     mne_swab);
  		kunmap(pages[i]);
  		if (rc2 < 0) {
  			CWARN("Process recover log %s error %d\n",
  			      cld->cld_logname, rc2);
  			break;
  		}
  
  		ealen -= PAGE_CACHE_SIZE;
  	}
  
  out:
  	if (req)
  		ptlrpc_req_finished(req);
  
  	if (rc == 0 && !eof)
  		goto again;
  
  	if (pages) {
  		for (i = 0; i < nrpages; i++) {
  			if (pages[i] == NULL)
  				break;
  			__free_page(pages[i]);
  		}
  		OBD_FREE(pages, sizeof(*pages) * nrpages);
  	}
  	return rc;
  }
  
  static int mgc_llog_local_copy(const struct lu_env *env,
  			       struct obd_device *obd,
  			       struct llog_ctxt *rctxt,
  			       struct llog_ctxt *lctxt, char *logname)
  {
  	char	*temp_log;
  	int	 rc;
  
  
  
  	/*
  	 * - copy it to backup using llog_backup()
  	 * - copy remote llog to logname using llog_backup()
  	 * - if failed then move backup to logname again
  	 */
  
  	OBD_ALLOC(temp_log, strlen(logname) + 1);
  	if (!temp_log)
  		return -ENOMEM;
  	sprintf(temp_log, "%sT", logname);
  
  	/* make a copy of local llog at first */
  	rc = llog_backup(env, obd, lctxt, lctxt, logname, temp_log);
  	if (rc < 0 && rc != -ENOENT)
  		GOTO(out, rc);
  	/* copy remote llog to the local copy */
  	rc = llog_backup(env, obd, rctxt, lctxt, logname, logname);
  	if (rc == -ENOENT) {
  		/* no remote llog, delete local one too */
  		llog_erase(env, lctxt, NULL, logname);
  	} else if (rc < 0) {
  		/* error during backup, get local one back from the copy */
  		llog_backup(env, obd, lctxt, lctxt, temp_log, logname);
  out:
  		CERROR("%s: failed to copy remote log %s: rc = %d\n",
  		       obd->obd_name, logname, rc);
  	}
  	llog_erase(env, lctxt, NULL, temp_log);
  	OBD_FREE(temp_log, strlen(logname) + 1);
  	return rc;
  }
  
  /* local_only means it cannot get remote llogs */
  static int mgc_process_cfg_log(struct obd_device *mgc,
  			       struct config_llog_data *cld, int local_only)
  {
  	struct llog_ctxt	*ctxt, *lctxt = NULL;
  	struct dt_object        *cl_mgc_dir = mgc->u.cli.cl_mgc_configs_dir;
  	struct lustre_sb_info	*lsi = NULL;
  	int			 rc = 0;
  	bool			 sptlrpc_started = false;
  	struct lu_env		*env;
  
  	LASSERT(cld);
  	LASSERT(mutex_is_locked(&cld->cld_lock));
  
  	/*
  	 * local copy of sptlrpc log is controlled elsewhere, don't try to
  	 * read it up here.
  	 */
  	if (cld_is_sptlrpc(cld) && local_only)
  		return 0;
  
  	if (cld->cld_cfg.cfg_sb)
  		lsi = s2lsi(cld->cld_cfg.cfg_sb);
  
  	OBD_ALLOC_PTR(env);
  	if (env == NULL)
  		return -ENOMEM;
  
  	rc = lu_env_init(env, LCT_MG_THREAD);
  	if (rc)
  		GOTO(out_free, rc);
  
  	ctxt = llog_get_context(mgc, LLOG_CONFIG_REPL_CTXT);
  	LASSERT(ctxt);
  
  	lctxt = llog_get_context(mgc, LLOG_CONFIG_ORIG_CTXT);
  
  	/* Copy the setup log locally if we can. Don't mess around if we're
  	 * running an MGS though (logs are already local). */
  	if (lctxt && lsi && IS_SERVER(lsi) && !IS_MGS(lsi) &&
  	    cl_mgc_dir != NULL &&
  	    lu2dt_dev(cl_mgc_dir->do_lu.lo_dev) == lsi->lsi_dt_dev) {
  		if (!local_only)
  			/* Only try to copy log if we have the lock. */
  			rc = mgc_llog_local_copy(env, mgc, ctxt, lctxt,
  						 cld->cld_logname);
  		if (local_only || rc) {
  			if (llog_is_empty(env, lctxt, cld->cld_logname)) {
  				LCONSOLE_ERROR_MSG(0x13a,
  						   "Failed to get MGS log %s and no local copy.\n",
  						   cld->cld_logname);
  				GOTO(out_pop, rc = -ENOENT);
  			}
  			CDEBUG(D_MGC,
  			       "Failed to get MGS log %s, using local copy for now, will try to update later.\n",
  			       cld->cld_logname);
  		}
  		/* Now, whether we copied or not, start using the local llog.
  		 * If we failed to copy, we'll start using whatever the old
  		 * log has. */
  		llog_ctxt_put(ctxt);
  		ctxt = lctxt;
  		lctxt = NULL;
  	} else {
  		if (local_only) /* no local log at client side */
  			GOTO(out_pop, rc = -EIO);
  	}
  
  	if (cld_is_sptlrpc(cld)) {
  		sptlrpc_conf_log_update_begin(cld->cld_logname);
  		sptlrpc_started = true;
  	}
  
  	/* logname and instance info should be the same, so use our
  	 * copy of the instance for the update.  The cfg_last_idx will
  	 * be updated here. */
  	rc = class_config_parse_llog(env, ctxt, cld->cld_logname,
  				     &cld->cld_cfg);
  
  out_pop:
  	__llog_ctxt_put(env, ctxt);
  	if (lctxt)
  		__llog_ctxt_put(env, lctxt);
  
  	/*
  	 * update settings on existing OBDs. doing it inside
  	 * of llog_process_lock so no device is attaching/detaching
  	 * in parallel.
  	 * the logname must be <fsname>-sptlrpc
  	 */
  	if (sptlrpc_started) {
  		LASSERT(cld_is_sptlrpc(cld));
  		sptlrpc_conf_log_update_end(cld->cld_logname);
  		class_notify_sptlrpc_conf(cld->cld_logname,
  					  strlen(cld->cld_logname) -
  					  strlen("-sptlrpc"));
  	}
  
  	lu_env_fini(env);
  out_free:
  	OBD_FREE_PTR(env);
  	return rc;
  }
  
  /** Get a config log from the MGS and process it.
   * This func is called for both clients and servers.
   * Copy the log locally before parsing it if appropriate (non-MGS server)
   */
  int mgc_process_log(struct obd_device *mgc, struct config_llog_data *cld)
  {
  	struct lustre_handle lockh = { 0 };
  	__u64 flags = LDLM_FL_NO_LRU;
  	int rc = 0, rcl;
  
  	LASSERT(cld);
  
  	/* I don't want multiple processes running process_log at once --
  	   sounds like badness.  It actually might be fine, as long as
  	   we're not trying to update from the same log
  	   simultaneously (in which case we should use a per-log sem.) */
  	mutex_lock(&cld->cld_lock);
  	if (cld->cld_stopping) {
  		mutex_unlock(&cld->cld_lock);
  		return 0;
  	}
  
  	OBD_FAIL_TIMEOUT(OBD_FAIL_MGC_PAUSE_PROCESS_LOG, 20);
  
  	CDEBUG(D_MGC, "Process log %s:%p from %d\n", cld->cld_logname,
  	       cld->cld_cfg.cfg_instance, cld->cld_cfg.cfg_last_idx + 1);
  
  	/* Get the cfg lock on the llog */
  	rcl = mgc_enqueue(mgc->u.cli.cl_mgc_mgsexp, NULL, LDLM_PLAIN, NULL,
  			  LCK_CR, &flags, NULL, NULL, NULL,
  			  cld, 0, NULL, &lockh);
  	if (rcl == 0) {
  		/* Get the cld, it will be released in mgc_blocking_ast. */
  		config_log_get(cld);
  		rc = ldlm_lock_set_data(&lockh, (void *)cld);
  		LASSERT(rc == 0);
  	} else {
  		CDEBUG(D_MGC, "Can't get cfg lock: %d\n", rcl);
  
  		/* mark cld_lostlock so that it will requeue
  		 * after MGC becomes available. */
  		cld->cld_lostlock = 1;
  		/* Get extra reference, it will be put in requeue thread */
  		config_log_get(cld);
  	}
  
  
  	if (cld_is_recover(cld)) {
  		rc = 0; /* this is not a fatal error for recover log */
  		if (rcl == 0)
  			rc = mgc_process_recover_log(mgc, cld);
  	} else {
  		rc = mgc_process_cfg_log(mgc, cld, rcl != 0);
  	}
  
  	CDEBUG(D_MGC, "%s: configuration from log '%s' %sed (%d).\n",
  	       mgc->obd_name, cld->cld_logname, rc ? "fail" : "succeed", rc);
  
  	mutex_unlock(&cld->cld_lock);
  
  	/* Now drop the lock so MGS can revoke it */
  	if (!rcl) {
  		rcl = mgc_cancel(mgc->u.cli.cl_mgc_mgsexp, NULL,
  				 LCK_CR, &lockh);
  		if (rcl)
  			CERROR("Can't drop cfg lock: %d\n", rcl);
  	}
  
  	return rc;
  }
  
  
  /** Called from lustre_process_log.
   * LCFG_LOG_START gets the config log from the MGS, processes it to start
   * any services, and adds it to the list logs to watch (follow).
   */
  static int mgc_process_config(struct obd_device *obd, obd_count len, void *buf)
  {
  	struct lustre_cfg *lcfg = buf;
  	struct config_llog_instance *cfg = NULL;
  	char *logname;
  	int rc = 0;
  
  	switch (lcfg->lcfg_command) {
  	case LCFG_LOV_ADD_OBD: {
  		/* Overloading this cfg command: register a new target */
  		struct mgs_target_info *mti;
  
  		if (LUSTRE_CFG_BUFLEN(lcfg, 1) !=
  		    sizeof(struct mgs_target_info))
  			GOTO(out, rc = -EINVAL);
  
  		mti = (struct mgs_target_info *)lustre_cfg_buf(lcfg, 1);
  		CDEBUG(D_MGC, "add_target %s %#x\n",
  		       mti->mti_svname, mti->mti_flags);
  		rc = mgc_target_register(obd->u.cli.cl_mgc_mgsexp, mti);
  		break;
  	}
  	case LCFG_LOV_DEL_OBD:
  		/* Unregister has no meaning at the moment. */
  		CERROR("lov_del_obd unimplemented\n");
  		rc = -ENOSYS;
  		break;
  	case LCFG_SPTLRPC_CONF: {
  		rc = sptlrpc_process_config(lcfg);
  		break;
  	}
  	case LCFG_LOG_START: {
  		struct config_llog_data *cld;
  		struct super_block *sb;
  
  		logname = lustre_cfg_string(lcfg, 1);
  		cfg = (struct config_llog_instance *)lustre_cfg_buf(lcfg, 2);
  		sb = *(struct super_block **)lustre_cfg_buf(lcfg, 3);
  
  		CDEBUG(D_MGC, "parse_log %s from %d\n", logname,
  		       cfg->cfg_last_idx);
  
  		/* We're only called through here on the initial mount */
  		rc = config_log_add(obd, logname, cfg, sb);
  		if (rc)
  			break;
  		cld = config_log_find(logname, cfg);
  		if (cld == NULL) {
  			rc = -ENOENT;
  			break;
  		}
  
  		/* COMPAT_146 */
  		/* FIXME only set this for old logs!  Right now this forces
  		   us to always skip the "inside markers" check */
  		cld->cld_cfg.cfg_flags |= CFG_F_COMPAT146;
  
  		rc = mgc_process_log(obd, cld);
  		if (rc == 0 && cld->cld_recover != NULL) {
  			if (OCD_HAS_FLAG(&obd->u.cli.cl_import->
  					 imp_connect_data, IMP_RECOV)) {
  				rc = mgc_process_log(obd, cld->cld_recover);
  			} else {
  				struct config_llog_data *cir = cld->cld_recover;
  				cld->cld_recover = NULL;
  				config_log_put(cir);
  			}
  			if (rc)
  				CERROR("Cannot process recover llog %d\n", rc);
  		}
  
  		if (rc == 0 && cld->cld_params != NULL) {
  			rc = mgc_process_log(obd, cld->cld_params);
  			if (rc == -ENOENT) {
  				CDEBUG(D_MGC,
  				       "There is no params config file yet\n");
  				rc = 0;
  			}
  			/* params log is optional */
  			if (rc)
  				CERROR(
  				       "%s: can't process params llog: rc = %d\n",
  				       obd->obd_name, rc);
  		}
  		config_log_put(cld);
  
  		break;
  	}
  	case LCFG_LOG_END: {
  		logname = lustre_cfg_string(lcfg, 1);
  
  		if (lcfg->lcfg_bufcount >= 2)
  			cfg = (struct config_llog_instance *)lustre_cfg_buf(
  				lcfg, 2);
  		rc = config_log_end(logname, cfg);
  		break;
  	}
  	default: {
  		CERROR("Unknown command: %d\n", lcfg->lcfg_command);
  		GOTO(out, rc = -EINVAL);
  
  	}
  	}
  out:
  	return rc;
  }
  
  struct obd_ops mgc_obd_ops = {
  	.o_owner	= THIS_MODULE,
  	.o_setup	= mgc_setup,
  	.o_precleanup   = mgc_precleanup,
  	.o_cleanup      = mgc_cleanup,
  	.o_add_conn     = client_import_add_conn,
  	.o_del_conn     = client_import_del_conn,
  	.o_connect      = client_connect_import,
  	.o_disconnect   = client_disconnect_export,
  	/* .o_enqueue      = mgc_enqueue, */
  	.o_cancel       = mgc_cancel,
  	/* .o_iocontrol    = mgc_iocontrol, */
  	.o_set_info_async = mgc_set_info_async,
  	.o_get_info       = mgc_get_info,
  	.o_import_event = mgc_import_event,
  	.o_process_config = mgc_process_config,
  };
  
  int __init mgc_init(void)
  {
  	return class_register_type(&mgc_obd_ops, NULL, NULL,
  				   LUSTRE_MGC_NAME, NULL);
  }
  
  static void /*__exit*/ mgc_exit(void)
  {
  	class_unregister_type(LUSTRE_MGC_NAME);
  }
  
  MODULE_AUTHOR("Sun Microsystems, Inc. <http://www.lustre.org/>");
  MODULE_DESCRIPTION("Lustre Management Client");
  MODULE_LICENSE("GPL");
  
  module_init(mgc_init);
  module_exit(mgc_exit);
  