/* -*- mode: c; c-basic-offset: 8; -*-
   * vim: noexpandtab sw=8 ts=8 sts=0:
   *
   * dlmglue.c
   *
   * Code which implements an OCFS2 specific interface to our DLM.
   *
   * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License as published by the Free Software Foundation; either
   * version 2 of the License, or (at your option) any later version.
   *
   * 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 for more details.
   *
   * You should have received a copy of the GNU General Public
   * License along with this program; if not, write to the
   * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   */
  
  #include <linux/types.h>
  #include <linux/slab.h>
  #include <linux/highmem.h>
  #include <linux/mm.h>

  #include <linux/kthread.h>
  #include <linux/pagemap.h>
  #include <linux/debugfs.h>
  #include <linux/seq_file.h>

  #include <linux/time.h>

  #include <linux/quotaops.h>

  #include <linux/sched/signal.h>

  #define MLOG_MASK_PREFIX ML_DLM_GLUE
  #include <cluster/masklog.h>
  
  #include "ocfs2.h"

  #include "ocfs2_lockingver.h"

  
  #include "alloc.h"

  #include "dcache.h"

  #include "dlmglue.h"
  #include "extent_map.h"

  #include "file.h"

  #include "heartbeat.h"
  #include "inode.h"
  #include "journal.h"

  #include "stackglue.h"

  #include "slot_map.h"
  #include "super.h"
  #include "uptodate.h"

  #include "quota.h"

  #include "refcounttree.h"

  #include "acl.h"

  
  #include "buffer_head_io.h"
  
  struct ocfs2_mask_waiter {
  	struct list_head	mw_item;
  	int			mw_status;
  	struct completion	mw_complete;
  	unsigned long		mw_mask;
  	unsigned long		mw_goal;

  #ifdef CONFIG_OCFS2_FS_STATS

  	ktime_t			mw_lock_start;

  #endif

  };

  static struct ocfs2_super *ocfs2_get_dentry_osb(struct ocfs2_lock_res *lockres);
  static struct ocfs2_super *ocfs2_get_inode_osb(struct ocfs2_lock_res *lockres);

  static struct ocfs2_super *ocfs2_get_file_osb(struct ocfs2_lock_res *lockres);

  static struct ocfs2_super *ocfs2_get_qinfo_osb(struct ocfs2_lock_res *lockres);

  /*

   * Return value from ->downconvert_worker functions.

   *

   * These control the precise actions of ocfs2_unblock_lock()

   * and ocfs2_process_blocked_lock()
   *
   */
  enum ocfs2_unblock_action {
  	UNBLOCK_CONTINUE	= 0, /* Continue downconvert */
  	UNBLOCK_CONTINUE_POST	= 1, /* Continue downconvert, fire
  				      * ->post_unlock callback */
  	UNBLOCK_STOP_POST	= 2, /* Do not downconvert, fire
  				      * ->post_unlock() callback. */
  };
  
  struct ocfs2_unblock_ctl {
  	int requeue;
  	enum ocfs2_unblock_action unblock_action;
  };

  /* Lockdep class keys */
  struct lock_class_key lockdep_keys[OCFS2_NUM_LOCK_TYPES];

  static int ocfs2_check_meta_downconvert(struct ocfs2_lock_res *lockres,
  					int new_level);
  static void ocfs2_set_meta_lvb(struct ocfs2_lock_res *lockres);

  static int ocfs2_data_convert_worker(struct ocfs2_lock_res *lockres,
  				     int blocking);

  static int ocfs2_dentry_convert_worker(struct ocfs2_lock_res *lockres,
  				       int blocking);

  
  static void ocfs2_dentry_post_unlock(struct ocfs2_super *osb,
  				     struct ocfs2_lock_res *lockres);

  static void ocfs2_set_qinfo_lvb(struct ocfs2_lock_res *lockres);

  static int ocfs2_check_refcount_downconvert(struct ocfs2_lock_res *lockres,
  					    int new_level);
  static int ocfs2_refcount_convert_worker(struct ocfs2_lock_res *lockres,
  					 int blocking);

  #define mlog_meta_lvb(__level, __lockres) ocfs2_dump_meta_lvb_info(__level, __PRETTY_FUNCTION__, __LINE__, __lockres)
  
  /* This aids in debugging situations where a bad LVB might be involved. */
  static void ocfs2_dump_meta_lvb_info(u64 level,
  				     const char *function,
  				     unsigned int line,
  				     struct ocfs2_lock_res *lockres)
  {

  	struct ocfs2_meta_lvb *lvb = ocfs2_dlm_lvb(&lockres->l_lksb);

  
  	mlog(level, "LVB information for %s (called from %s:%u):
  ",
  	     lockres->l_name, function, line);
  	mlog(level, "version: %u, clusters: %u, generation: 0x%x
  ",
  	     lvb->lvb_version, be32_to_cpu(lvb->lvb_iclusters),
  	     be32_to_cpu(lvb->lvb_igeneration));
  	mlog(level, "size: %llu, uid %u, gid %u, mode 0x%x
  ",
  	     (unsigned long long)be64_to_cpu(lvb->lvb_isize),
  	     be32_to_cpu(lvb->lvb_iuid), be32_to_cpu(lvb->lvb_igid),
  	     be16_to_cpu(lvb->lvb_imode));
  	mlog(level, "nlink %u, atime_packed 0x%llx, ctime_packed 0x%llx, "
  	     "mtime_packed 0x%llx iattr 0x%x
  ", be16_to_cpu(lvb->lvb_inlink),
  	     (long long)be64_to_cpu(lvb->lvb_iatime_packed),
  	     (long long)be64_to_cpu(lvb->lvb_ictime_packed),
  	     (long long)be64_to_cpu(lvb->lvb_imtime_packed),
  	     be32_to_cpu(lvb->lvb_iattr));
  }

  /*
   * OCFS2 Lock Resource Operations
   *
   * These fine tune the behavior of the generic dlmglue locking infrastructure.

   *
   * The most basic of lock types can point ->l_priv to their respective
   * struct ocfs2_super and allow the default actions to manage things.
   *
   * Right now, each lock type also needs to implement an init function,
   * and trivial lock/unlock wrappers. ocfs2_simple_drop_lockres()
   * should be called when the lock is no longer needed (i.e., object
   * destruction time).

   */

  struct ocfs2_lock_res_ops {

  	/*
  	 * Translate an ocfs2_lock_res * into an ocfs2_super *. Define
  	 * this callback if ->l_priv is not an ocfs2_super pointer
  	 */
  	struct ocfs2_super * (*get_osb)(struct ocfs2_lock_res *);

  	/*

  	 * Optionally called in the downconvert thread after a
  	 * successful downconvert. The lockres will not be referenced
  	 * after this callback is called, so it is safe to free
  	 * memory, etc.

  	 *
  	 * The exact semantics of when this is called are controlled
  	 * by ->downconvert_worker()
  	 */

  	void (*post_unlock)(struct ocfs2_super *, struct ocfs2_lock_res *);

  
  	/*

  	 * Allow a lock type to add checks to determine whether it is
  	 * safe to downconvert a lock. Return 0 to re-queue the
  	 * downconvert at a later time, nonzero to continue.
  	 *
  	 * For most locks, the default checks that there are no
  	 * incompatible holders are sufficient.
  	 *
  	 * Called with the lockres spinlock held.
  	 */
  	int (*check_downconvert)(struct ocfs2_lock_res *, int);
  
  	/*

  	 * Allows a lock type to populate the lock value block. This
  	 * is called on downconvert, and when we drop a lock.
  	 *
  	 * Locks that want to use this should set LOCK_TYPE_USES_LVB
  	 * in the flags field.
  	 *
  	 * Called with the lockres spinlock held.
  	 */
  	void (*set_lvb)(struct ocfs2_lock_res *);
  
  	/*

  	 * Called from the downconvert thread when it is determined
  	 * that a lock will be downconverted. This is called without
  	 * any locks held so the function can do work that might
  	 * schedule (syncing out data, etc).
  	 *
  	 * This should return any one of the ocfs2_unblock_action
  	 * values, depending on what it wants the thread to do.
  	 */
  	int (*downconvert_worker)(struct ocfs2_lock_res *, int);
  
  	/*

  	 * LOCK_TYPE_* flags which describe the specific requirements
  	 * of a lock type. Descriptions of each individual flag follow.
  	 */
  	int flags;

  };

  /*
   * Some locks want to "refresh" potentially stale data when a
   * meaningful (PRMODE or EXMODE) lock level is first obtained. If this
   * flag is set, the OCFS2_LOCK_NEEDS_REFRESH flag will be set on the
   * individual lockres l_flags member from the ast function. It is
   * expected that the locking wrapper will clear the
   * OCFS2_LOCK_NEEDS_REFRESH flag when done.
   */
  #define LOCK_TYPE_REQUIRES_REFRESH 0x1

  /*

   * Indicate that a lock type makes use of the lock value block. The
   * ->set_lvb lock type callback must be defined.

   */
  #define LOCK_TYPE_USES_LVB		0x2

  static struct ocfs2_lock_res_ops ocfs2_inode_rw_lops = {

  	.get_osb	= ocfs2_get_inode_osb,

  	.flags		= 0,

  };

  static struct ocfs2_lock_res_ops ocfs2_inode_inode_lops = {

  	.get_osb	= ocfs2_get_inode_osb,

  	.check_downconvert = ocfs2_check_meta_downconvert,
  	.set_lvb	= ocfs2_set_meta_lvb,

  	.downconvert_worker = ocfs2_data_convert_worker,

  	.flags		= LOCK_TYPE_REQUIRES_REFRESH|LOCK_TYPE_USES_LVB,

  };

  static struct ocfs2_lock_res_ops ocfs2_super_lops = {

  	.flags		= LOCK_TYPE_REQUIRES_REFRESH,

  };
  
  static struct ocfs2_lock_res_ops ocfs2_rename_lops = {

  	.flags		= 0,

  };

  static struct ocfs2_lock_res_ops ocfs2_nfs_sync_lops = {
  	.flags		= 0,
  };

  static struct ocfs2_lock_res_ops ocfs2_orphan_scan_lops = {
  	.flags		= LOCK_TYPE_REQUIRES_REFRESH|LOCK_TYPE_USES_LVB,
  };

  static struct ocfs2_lock_res_ops ocfs2_dentry_lops = {

  	.get_osb	= ocfs2_get_dentry_osb,

  	.post_unlock	= ocfs2_dentry_post_unlock,

  	.downconvert_worker = ocfs2_dentry_convert_worker,

  	.flags		= 0,

  };

  static struct ocfs2_lock_res_ops ocfs2_inode_open_lops = {
  	.get_osb	= ocfs2_get_inode_osb,
  	.flags		= 0,
  };

  static struct ocfs2_lock_res_ops ocfs2_flock_lops = {
  	.get_osb	= ocfs2_get_file_osb,
  	.flags		= 0,
  };

  static struct ocfs2_lock_res_ops ocfs2_qinfo_lops = {
  	.set_lvb	= ocfs2_set_qinfo_lvb,
  	.get_osb	= ocfs2_get_qinfo_osb,
  	.flags		= LOCK_TYPE_REQUIRES_REFRESH | LOCK_TYPE_USES_LVB,
  };

  static struct ocfs2_lock_res_ops ocfs2_refcount_block_lops = {
  	.check_downconvert = ocfs2_check_refcount_downconvert,
  	.downconvert_worker = ocfs2_refcount_convert_worker,
  	.flags		= 0,
  };

  static inline int ocfs2_is_inode_lock(struct ocfs2_lock_res *lockres)
  {
  	return lockres->l_type == OCFS2_LOCK_TYPE_META ||

  		lockres->l_type == OCFS2_LOCK_TYPE_RW ||
  		lockres->l_type == OCFS2_LOCK_TYPE_OPEN;

  }

  static inline struct ocfs2_lock_res *ocfs2_lksb_to_lock_res(struct ocfs2_dlm_lksb *lksb)

  {
  	return container_of(lksb, struct ocfs2_lock_res, l_lksb);
  }

  static inline struct inode *ocfs2_lock_res_inode(struct ocfs2_lock_res *lockres)
  {
  	BUG_ON(!ocfs2_is_inode_lock(lockres));
  
  	return (struct inode *) lockres->l_priv;
  }

  static inline struct ocfs2_dentry_lock *ocfs2_lock_res_dl(struct ocfs2_lock_res *lockres)
  {
  	BUG_ON(lockres->l_type != OCFS2_LOCK_TYPE_DENTRY);
  
  	return (struct ocfs2_dentry_lock *)lockres->l_priv;
  }

  static inline struct ocfs2_mem_dqinfo *ocfs2_lock_res_qinfo(struct ocfs2_lock_res *lockres)
  {
  	BUG_ON(lockres->l_type != OCFS2_LOCK_TYPE_QINFO);
  
  	return (struct ocfs2_mem_dqinfo *)lockres->l_priv;
  }

  static inline struct ocfs2_refcount_tree *
  ocfs2_lock_res_refcount_tree(struct ocfs2_lock_res *res)
  {
  	return container_of(res, struct ocfs2_refcount_tree, rf_lockres);
  }

  static inline struct ocfs2_super *ocfs2_get_lockres_osb(struct ocfs2_lock_res *lockres)
  {
  	if (lockres->l_ops->get_osb)
  		return lockres->l_ops->get_osb(lockres);
  
  	return (struct ocfs2_super *)lockres->l_priv;
  }

  static int ocfs2_lock_create(struct ocfs2_super *osb,
  			     struct ocfs2_lock_res *lockres,
  			     int level,

  			     u32 dlm_flags);

  static inline int ocfs2_may_continue_on_blocked_lock(struct ocfs2_lock_res *lockres,
  						     int wanted);

  static void __ocfs2_cluster_unlock(struct ocfs2_super *osb,
  				   struct ocfs2_lock_res *lockres,
  				   int level, unsigned long caller_ip);
  static inline void ocfs2_cluster_unlock(struct ocfs2_super *osb,
  					struct ocfs2_lock_res *lockres,
  					int level)
  {
  	__ocfs2_cluster_unlock(osb, lockres, level, _RET_IP_);
  }

  static inline void ocfs2_generic_handle_downconvert_action(struct ocfs2_lock_res *lockres);
  static inline void ocfs2_generic_handle_convert_action(struct ocfs2_lock_res *lockres);
  static inline void ocfs2_generic_handle_attach_action(struct ocfs2_lock_res *lockres);
  static int ocfs2_generic_handle_bast(struct ocfs2_lock_res *lockres, int level);
  static void ocfs2_schedule_blocked_lock(struct ocfs2_super *osb,
  					struct ocfs2_lock_res *lockres);
  static inline void ocfs2_recover_from_dlm_error(struct ocfs2_lock_res *lockres,
  						int convert);

  #define ocfs2_log_dlm_error(_func, _err, _lockres) do {					\
  	if ((_lockres)->l_type != OCFS2_LOCK_TYPE_DENTRY)				\
  		mlog(ML_ERROR, "DLM error %d while calling %s on resource %s
  ",	\
  		     _err, _func, _lockres->l_name);					\
  	else										\
  		mlog(ML_ERROR, "DLM error %d while calling %s on resource %.*s%08x
  ",	\
  		     _err, _func, OCFS2_DENTRY_LOCK_INO_START - 1, (_lockres)->l_name,	\
  		     (unsigned int)ocfs2_get_dentry_lock_ino(_lockres));		\

  } while (0)

  static int ocfs2_downconvert_thread(void *arg);
  static void ocfs2_downconvert_on_unlock(struct ocfs2_super *osb,
  					struct ocfs2_lock_res *lockres);

  static int ocfs2_inode_lock_update(struct inode *inode,

  				  struct buffer_head **bh);
  static void ocfs2_drop_osb_locks(struct ocfs2_super *osb);
  static inline int ocfs2_highest_compat_lock_level(int level);

  static unsigned int ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
  					      int new_level);

  static int ocfs2_downconvert_lock(struct ocfs2_super *osb,
  				  struct ocfs2_lock_res *lockres,
  				  int new_level,

  				  int lvb,
  				  unsigned int generation);

  static int ocfs2_prepare_cancel_convert(struct ocfs2_super *osb,
  				        struct ocfs2_lock_res *lockres);
  static int ocfs2_cancel_convert(struct ocfs2_super *osb,
  				struct ocfs2_lock_res *lockres);

  static void ocfs2_build_lock_name(enum ocfs2_lock_type type,
  				  u64 blkno,
  				  u32 generation,
  				  char *name)
  {
  	int len;

  	BUG_ON(type >= OCFS2_NUM_LOCK_TYPES);

  	len = snprintf(name, OCFS2_LOCK_ID_MAX_LEN, "%c%s%016llx%08x",
  		       ocfs2_lock_type_char(type), OCFS2_LOCK_ID_PAD,
  		       (long long)blkno, generation);

  
  	BUG_ON(len != (OCFS2_LOCK_ID_MAX_LEN - 1));
  
  	mlog(0, "built lock resource with name: %s
  ", name);

  }

  static DEFINE_SPINLOCK(ocfs2_dlm_tracking_lock);

  
  static void ocfs2_add_lockres_tracking(struct ocfs2_lock_res *res,
  				       struct ocfs2_dlm_debug *dlm_debug)
  {
  	mlog(0, "Add tracking for lockres %s
  ", res->l_name);
  
  	spin_lock(&ocfs2_dlm_tracking_lock);
  	list_add(&res->l_debug_list, &dlm_debug->d_lockres_tracking);
  	spin_unlock(&ocfs2_dlm_tracking_lock);
  }
  
  static void ocfs2_remove_lockres_tracking(struct ocfs2_lock_res *res)
  {
  	spin_lock(&ocfs2_dlm_tracking_lock);
  	if (!list_empty(&res->l_debug_list))
  		list_del_init(&res->l_debug_list);
  	spin_unlock(&ocfs2_dlm_tracking_lock);
  }

  #ifdef CONFIG_OCFS2_FS_STATS
  static void ocfs2_init_lock_stats(struct ocfs2_lock_res *res)
  {

  	res->l_lock_refresh = 0;

  	memset(&res->l_lock_prmode, 0, sizeof(struct ocfs2_lock_stats));
  	memset(&res->l_lock_exmode, 0, sizeof(struct ocfs2_lock_stats));

  }
  
  static void ocfs2_update_lock_stats(struct ocfs2_lock_res *res, int level,
  				    struct ocfs2_mask_waiter *mw, int ret)
  {

  	u32 usec;
  	ktime_t kt;
  	struct ocfs2_lock_stats *stats;
  
  	if (level == LKM_PRMODE)
  		stats = &res->l_lock_prmode;
  	else if (level == LKM_EXMODE)
  		stats = &res->l_lock_exmode;
  	else

  		return;

  	kt = ktime_sub(ktime_get(), mw->mw_lock_start);
  	usec = ktime_to_us(kt);
  
  	stats->ls_gets++;
  	stats->ls_total += ktime_to_ns(kt);
  	/* overflow */

  	if (unlikely(stats->ls_gets == 0)) {

  		stats->ls_gets++;
  		stats->ls_total = ktime_to_ns(kt);
  	}
  
  	if (stats->ls_max < usec)
  		stats->ls_max = usec;

  	if (ret)

  		stats->ls_fail++;

  }
  
  static inline void ocfs2_track_lock_refresh(struct ocfs2_lock_res *lockres)
  {
  	lockres->l_lock_refresh++;
  }
  
  static inline void ocfs2_init_start_time(struct ocfs2_mask_waiter *mw)
  {

  	mw->mw_lock_start = ktime_get();

  }
  #else
  static inline void ocfs2_init_lock_stats(struct ocfs2_lock_res *res)
  {
  }
  static inline void ocfs2_update_lock_stats(struct ocfs2_lock_res *res,
  			   int level, struct ocfs2_mask_waiter *mw, int ret)
  {
  }
  static inline void ocfs2_track_lock_refresh(struct ocfs2_lock_res *lockres)
  {
  }
  static inline void ocfs2_init_start_time(struct ocfs2_mask_waiter *mw)
  {
  }
  #endif

  static void ocfs2_lock_res_init_common(struct ocfs2_super *osb,
  				       struct ocfs2_lock_res *res,
  				       enum ocfs2_lock_type type,

  				       struct ocfs2_lock_res_ops *ops,
  				       void *priv)
  {

  	res->l_type          = type;
  	res->l_ops           = ops;
  	res->l_priv          = priv;

  	res->l_level         = DLM_LOCK_IV;
  	res->l_requested     = DLM_LOCK_IV;
  	res->l_blocking      = DLM_LOCK_IV;

  	res->l_action        = OCFS2_AST_INVALID;
  	res->l_unlock_action = OCFS2_UNLOCK_INVALID;
  
  	res->l_flags         = OCFS2_LOCK_INITIALIZED;
  
  	ocfs2_add_lockres_tracking(res, osb->osb_dlm_debug);

  
  	ocfs2_init_lock_stats(res);

  #ifdef CONFIG_DEBUG_LOCK_ALLOC
  	if (type != OCFS2_LOCK_TYPE_OPEN)
  		lockdep_init_map(&res->l_lockdep_map, ocfs2_lock_type_strings[type],
  				 &lockdep_keys[type], 0);
  	else
  		res->l_lockdep_map.key = NULL;
  #endif

  }
  
  void ocfs2_lock_res_init_once(struct ocfs2_lock_res *res)
  {
  	/* This also clears out the lock status block */
  	memset(res, 0, sizeof(struct ocfs2_lock_res));
  	spin_lock_init(&res->l_lock);
  	init_waitqueue_head(&res->l_event);
  	INIT_LIST_HEAD(&res->l_blocked_list);
  	INIT_LIST_HEAD(&res->l_mask_waiters);

  	INIT_LIST_HEAD(&res->l_holders);

  }
  
  void ocfs2_inode_lock_res_init(struct ocfs2_lock_res *res,
  			       enum ocfs2_lock_type type,

  			       unsigned int generation,

  			       struct inode *inode)
  {
  	struct ocfs2_lock_res_ops *ops;
  
  	switch(type) {
  		case OCFS2_LOCK_TYPE_RW:
  			ops = &ocfs2_inode_rw_lops;
  			break;
  		case OCFS2_LOCK_TYPE_META:

  			ops = &ocfs2_inode_inode_lops;

  			break;

  		case OCFS2_LOCK_TYPE_OPEN:
  			ops = &ocfs2_inode_open_lops;
  			break;

  		default:
  			mlog_bug_on_msg(1, "type: %d
  ", type);
  			ops = NULL; /* thanks, gcc */
  			break;
  	};

  	ocfs2_build_lock_name(type, OCFS2_I(inode)->ip_blkno,

  			      generation, res->l_name);

  	ocfs2_lock_res_init_common(OCFS2_SB(inode->i_sb), res, type, ops, inode);
  }

  static struct ocfs2_super *ocfs2_get_inode_osb(struct ocfs2_lock_res *lockres)
  {
  	struct inode *inode = ocfs2_lock_res_inode(lockres);
  
  	return OCFS2_SB(inode->i_sb);
  }

  static struct ocfs2_super *ocfs2_get_qinfo_osb(struct ocfs2_lock_res *lockres)
  {
  	struct ocfs2_mem_dqinfo *info = lockres->l_priv;
  
  	return OCFS2_SB(info->dqi_gi.dqi_sb);
  }

  static struct ocfs2_super *ocfs2_get_file_osb(struct ocfs2_lock_res *lockres)
  {
  	struct ocfs2_file_private *fp = lockres->l_priv;
  
  	return OCFS2_SB(fp->fp_file->f_mapping->host->i_sb);
  }

  static __u64 ocfs2_get_dentry_lock_ino(struct ocfs2_lock_res *lockres)
  {
  	__be64 inode_blkno_be;
  
  	memcpy(&inode_blkno_be, &lockres->l_name[OCFS2_DENTRY_LOCK_INO_START],
  	       sizeof(__be64));
  
  	return be64_to_cpu(inode_blkno_be);
  }

  static struct ocfs2_super *ocfs2_get_dentry_osb(struct ocfs2_lock_res *lockres)
  {
  	struct ocfs2_dentry_lock *dl = lockres->l_priv;
  
  	return OCFS2_SB(dl->dl_inode->i_sb);
  }

  void ocfs2_dentry_lock_res_init(struct ocfs2_dentry_lock *dl,
  				u64 parent, struct inode *inode)
  {
  	int len;
  	u64 inode_blkno = OCFS2_I(inode)->ip_blkno;
  	__be64 inode_blkno_be = cpu_to_be64(inode_blkno);
  	struct ocfs2_lock_res *lockres = &dl->dl_lockres;
  
  	ocfs2_lock_res_init_once(lockres);
  
  	/*
  	 * Unfortunately, the standard lock naming scheme won't work
  	 * here because we have two 16 byte values to use. Instead,
  	 * we'll stuff the inode number as a binary value. We still
  	 * want error prints to show something without garbling the
  	 * display, so drop a null byte in there before the inode
  	 * number. A future version of OCFS2 will likely use all
  	 * binary lock names. The stringified names have been a
  	 * tremendous aid in debugging, but now that the debugfs
  	 * interface exists, we can mangle things there if need be.
  	 *
  	 * NOTE: We also drop the standard "pad" value (the total lock
  	 * name size stays the same though - the last part is all
  	 * zeros due to the memset in ocfs2_lock_res_init_once()
  	 */
  	len = snprintf(lockres->l_name, OCFS2_DENTRY_LOCK_INO_START,
  		       "%c%016llx",
  		       ocfs2_lock_type_char(OCFS2_LOCK_TYPE_DENTRY),
  		       (long long)parent);
  
  	BUG_ON(len != (OCFS2_DENTRY_LOCK_INO_START - 1));
  
  	memcpy(&lockres->l_name[OCFS2_DENTRY_LOCK_INO_START], &inode_blkno_be,
  	       sizeof(__be64));
  
  	ocfs2_lock_res_init_common(OCFS2_SB(inode->i_sb), lockres,
  				   OCFS2_LOCK_TYPE_DENTRY, &ocfs2_dentry_lops,
  				   dl);

  }
  
  static void ocfs2_super_lock_res_init(struct ocfs2_lock_res *res,
  				      struct ocfs2_super *osb)
  {
  	/* Superblock lockres doesn't come from a slab so we call init
  	 * once on it manually.  */
  	ocfs2_lock_res_init_once(res);

  	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_SUPER, OCFS2_SUPER_BLOCK_BLKNO,
  			      0, res->l_name);

  	ocfs2_lock_res_init_common(osb, res, OCFS2_LOCK_TYPE_SUPER,

  				   &ocfs2_super_lops, osb);
  }
  
  static void ocfs2_rename_lock_res_init(struct ocfs2_lock_res *res,
  				       struct ocfs2_super *osb)
  {
  	/* Rename lockres doesn't come from a slab so we call init
  	 * once on it manually.  */
  	ocfs2_lock_res_init_once(res);

  	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_RENAME, 0, 0, res->l_name);
  	ocfs2_lock_res_init_common(osb, res, OCFS2_LOCK_TYPE_RENAME,

  				   &ocfs2_rename_lops, osb);
  }

  static void ocfs2_nfs_sync_lock_res_init(struct ocfs2_lock_res *res,
  					 struct ocfs2_super *osb)
  {
  	/* nfs_sync lockres doesn't come from a slab so we call init
  	 * once on it manually.  */
  	ocfs2_lock_res_init_once(res);
  	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_NFS_SYNC, 0, 0, res->l_name);
  	ocfs2_lock_res_init_common(osb, res, OCFS2_LOCK_TYPE_NFS_SYNC,
  				   &ocfs2_nfs_sync_lops, osb);
  }

  static void ocfs2_orphan_scan_lock_res_init(struct ocfs2_lock_res *res,
  					    struct ocfs2_super *osb)
  {

  	ocfs2_lock_res_init_once(res);
  	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_ORPHAN_SCAN, 0, 0, res->l_name);
  	ocfs2_lock_res_init_common(osb, res, OCFS2_LOCK_TYPE_ORPHAN_SCAN,
  				   &ocfs2_orphan_scan_lops, osb);

  }

  void ocfs2_file_lock_res_init(struct ocfs2_lock_res *lockres,
  			      struct ocfs2_file_private *fp)
  {
  	struct inode *inode = fp->fp_file->f_mapping->host;
  	struct ocfs2_inode_info *oi = OCFS2_I(inode);
  
  	ocfs2_lock_res_init_once(lockres);
  	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_FLOCK, oi->ip_blkno,
  			      inode->i_generation, lockres->l_name);
  	ocfs2_lock_res_init_common(OCFS2_SB(inode->i_sb), lockres,
  				   OCFS2_LOCK_TYPE_FLOCK, &ocfs2_flock_lops,
  				   fp);
  	lockres->l_flags |= OCFS2_LOCK_NOCACHE;
  }

  void ocfs2_qinfo_lock_res_init(struct ocfs2_lock_res *lockres,
  			       struct ocfs2_mem_dqinfo *info)
  {
  	ocfs2_lock_res_init_once(lockres);
  	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_QINFO, info->dqi_gi.dqi_type,
  			      0, lockres->l_name);
  	ocfs2_lock_res_init_common(OCFS2_SB(info->dqi_gi.dqi_sb), lockres,
  				   OCFS2_LOCK_TYPE_QINFO, &ocfs2_qinfo_lops,
  				   info);
  }

  void ocfs2_refcount_lock_res_init(struct ocfs2_lock_res *lockres,
  				  struct ocfs2_super *osb, u64 ref_blkno,
  				  unsigned int generation)
  {
  	ocfs2_lock_res_init_once(lockres);
  	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_REFCOUNT, ref_blkno,
  			      generation, lockres->l_name);
  	ocfs2_lock_res_init_common(osb, lockres, OCFS2_LOCK_TYPE_REFCOUNT,
  				   &ocfs2_refcount_block_lops, osb);
  }

  void ocfs2_lock_res_free(struct ocfs2_lock_res *res)
  {

  	if (!(res->l_flags & OCFS2_LOCK_INITIALIZED))
  		return;
  
  	ocfs2_remove_lockres_tracking(res);
  
  	mlog_bug_on_msg(!list_empty(&res->l_blocked_list),
  			"Lockres %s is on the blocked list
  ",
  			res->l_name);
  	mlog_bug_on_msg(!list_empty(&res->l_mask_waiters),
  			"Lockres %s has mask waiters pending
  ",
  			res->l_name);
  	mlog_bug_on_msg(spin_is_locked(&res->l_lock),
  			"Lockres %s is locked
  ",
  			res->l_name);
  	mlog_bug_on_msg(res->l_ro_holders,
  			"Lockres %s has %u ro holders
  ",
  			res->l_name, res->l_ro_holders);
  	mlog_bug_on_msg(res->l_ex_holders,
  			"Lockres %s has %u ex holders
  ",
  			res->l_name, res->l_ex_holders);
  
  	/* Need to clear out the lock status block for the dlm */
  	memset(&res->l_lksb, 0, sizeof(res->l_lksb));
  
  	res->l_flags = 0UL;

  }

  /*
   * Keep a list of processes who have interest in a lockres.
   * Note: this is now only uesed for check recursive cluster locking.
   */
  static inline void ocfs2_add_holder(struct ocfs2_lock_res *lockres,
  				   struct ocfs2_lock_holder *oh)
  {
  	INIT_LIST_HEAD(&oh->oh_list);
  	oh->oh_owner_pid = get_pid(task_pid(current));
  
  	spin_lock(&lockres->l_lock);
  	list_add_tail(&oh->oh_list, &lockres->l_holders);
  	spin_unlock(&lockres->l_lock);
  }
  
  static inline void ocfs2_remove_holder(struct ocfs2_lock_res *lockres,
  				       struct ocfs2_lock_holder *oh)
  {
  	spin_lock(&lockres->l_lock);
  	list_del(&oh->oh_list);
  	spin_unlock(&lockres->l_lock);
  
  	put_pid(oh->oh_owner_pid);
  }
  
  static inline int ocfs2_is_locked_by_me(struct ocfs2_lock_res *lockres)
  {
  	struct ocfs2_lock_holder *oh;
  	struct pid *pid;
  
  	/* look in the list of holders for one with the current task as owner */
  	spin_lock(&lockres->l_lock);
  	pid = task_pid(current);
  	list_for_each_entry(oh, &lockres->l_holders, oh_list) {
  		if (oh->oh_owner_pid == pid) {
  			spin_unlock(&lockres->l_lock);
  			return 1;
  		}
  	}
  	spin_unlock(&lockres->l_lock);
  
  	return 0;
  }

  static inline void ocfs2_inc_holders(struct ocfs2_lock_res *lockres,
  				     int level)
  {

  	BUG_ON(!lockres);
  
  	switch(level) {

  	case DLM_LOCK_EX:

  		lockres->l_ex_holders++;
  		break;

  	case DLM_LOCK_PR:

  		lockres->l_ro_holders++;
  		break;
  	default:
  		BUG();
  	}

  }
  
  static inline void ocfs2_dec_holders(struct ocfs2_lock_res *lockres,
  				     int level)
  {

  	BUG_ON(!lockres);
  
  	switch(level) {

  	case DLM_LOCK_EX:

  		BUG_ON(!lockres->l_ex_holders);
  		lockres->l_ex_holders--;
  		break;

  	case DLM_LOCK_PR:

  		BUG_ON(!lockres->l_ro_holders);
  		lockres->l_ro_holders--;
  		break;
  	default:
  		BUG();
  	}

  }
  
  /* WARNING: This function lives in a world where the only three lock
   * levels are EX, PR, and NL. It *will* have to be adjusted when more
   * lock types are added. */
  static inline int ocfs2_highest_compat_lock_level(int level)
  {

  	int new_level = DLM_LOCK_EX;

  	if (level == DLM_LOCK_EX)
  		new_level = DLM_LOCK_NL;
  	else if (level == DLM_LOCK_PR)
  		new_level = DLM_LOCK_PR;

  	return new_level;
  }
  
  static void lockres_set_flags(struct ocfs2_lock_res *lockres,
  			      unsigned long newflags)
  {

  	struct ocfs2_mask_waiter *mw, *tmp;

  
   	assert_spin_locked(&lockres->l_lock);
  
  	lockres->l_flags = newflags;

  	list_for_each_entry_safe(mw, tmp, &lockres->l_mask_waiters, mw_item) {

  		if ((lockres->l_flags & mw->mw_mask) != mw->mw_goal)
  			continue;
  
  		list_del_init(&mw->mw_item);
  		mw->mw_status = 0;
  		complete(&mw->mw_complete);
  	}
  }
  static void lockres_or_flags(struct ocfs2_lock_res *lockres, unsigned long or)
  {
  	lockres_set_flags(lockres, lockres->l_flags | or);
  }
  static void lockres_clear_flags(struct ocfs2_lock_res *lockres,
  				unsigned long clear)
  {
  	lockres_set_flags(lockres, lockres->l_flags & ~clear);
  }
  
  static inline void ocfs2_generic_handle_downconvert_action(struct ocfs2_lock_res *lockres)
  {

  	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BUSY));
  	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_ATTACHED));
  	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BLOCKED));

  	BUG_ON(lockres->l_blocking <= DLM_LOCK_NL);

  
  	lockres->l_level = lockres->l_requested;
  	if (lockres->l_level <=
  	    ocfs2_highest_compat_lock_level(lockres->l_blocking)) {

  		lockres->l_blocking = DLM_LOCK_NL;

  		lockres_clear_flags(lockres, OCFS2_LOCK_BLOCKED);
  	}
  	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);

  }
  
  static inline void ocfs2_generic_handle_convert_action(struct ocfs2_lock_res *lockres)
  {

  	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BUSY));
  	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_ATTACHED));
  
  	/* Convert from RO to EX doesn't really need anything as our
  	 * information is already up to data. Convert from NL to
  	 * *anything* however should mark ourselves as needing an
  	 * update */

  	if (lockres->l_level == DLM_LOCK_NL &&

  	    lockres->l_ops->flags & LOCK_TYPE_REQUIRES_REFRESH)

  		lockres_or_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
  
  	lockres->l_level = lockres->l_requested;

  
  	/*
  	 * We set the OCFS2_LOCK_UPCONVERT_FINISHING flag before clearing
  	 * the OCFS2_LOCK_BUSY flag to prevent the dc thread from
  	 * downconverting the lock before the upconvert has fully completed.

  	 * Do not prevent the dc thread from downconverting if NONBLOCK lock
  	 * had already returned.

  	 */

  	if (!(lockres->l_flags & OCFS2_LOCK_NONBLOCK_FINISHED))
  		lockres_or_flags(lockres, OCFS2_LOCK_UPCONVERT_FINISHING);
  	else
  		lockres_clear_flags(lockres, OCFS2_LOCK_NONBLOCK_FINISHED);

  	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);

  }
  
  static inline void ocfs2_generic_handle_attach_action(struct ocfs2_lock_res *lockres)
  {

  	BUG_ON((!(lockres->l_flags & OCFS2_LOCK_BUSY)));

  	BUG_ON(lockres->l_flags & OCFS2_LOCK_ATTACHED);

  	if (lockres->l_requested > DLM_LOCK_NL &&

  	    !(lockres->l_flags & OCFS2_LOCK_LOCAL) &&
  	    lockres->l_ops->flags & LOCK_TYPE_REQUIRES_REFRESH)

  		lockres_or_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
  
  	lockres->l_level = lockres->l_requested;
  	lockres_or_flags(lockres, OCFS2_LOCK_ATTACHED);
  	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);

  }

  static int ocfs2_generic_handle_bast(struct ocfs2_lock_res *lockres,
  				     int level)
  {
  	int needs_downconvert = 0;

  
  	assert_spin_locked(&lockres->l_lock);

  	if (level > lockres->l_blocking) {
  		/* only schedule a downconvert if we haven't already scheduled
  		 * one that goes low enough to satisfy the level we're
  		 * blocking.  this also catches the case where we get
  		 * duplicate BASTs */
  		if (ocfs2_highest_compat_lock_level(level) <
  		    ocfs2_highest_compat_lock_level(lockres->l_blocking))
  			needs_downconvert = 1;
  
  		lockres->l_blocking = level;
  	}

  	mlog(ML_BASTS, "lockres %s, block %d, level %d, l_block %d, dwn %d
  ",
  	     lockres->l_name, level, lockres->l_level, lockres->l_blocking,
  	     needs_downconvert);

  	if (needs_downconvert)
  		lockres_or_flags(lockres, OCFS2_LOCK_BLOCKED);

  	mlog(0, "needs_downconvert = %d
  ", needs_downconvert);

  	return needs_downconvert;
  }

  /*
   * OCFS2_LOCK_PENDING and l_pending_gen.
   *
   * Why does OCFS2_LOCK_PENDING exist?  To close a race between setting
   * OCFS2_LOCK_BUSY and calling ocfs2_dlm_lock().  See ocfs2_unblock_lock()
   * for more details on the race.
   *
   * OCFS2_LOCK_PENDING closes the race quite nicely.  However, it introduces
   * a race on itself.  In o2dlm, we can get the ast before ocfs2_dlm_lock()
   * returns.  The ast clears OCFS2_LOCK_BUSY, and must therefore clear
   * OCFS2_LOCK_PENDING at the same time.  When ocfs2_dlm_lock() returns,
   * the caller is going to try to clear PENDING again.  If nothing else is
   * happening, __lockres_clear_pending() sees PENDING is unset and does
   * nothing.
   *
   * But what if another path (eg downconvert thread) has just started a
   * new locking action?  The other path has re-set PENDING.  Our path
   * cannot clear PENDING, because that will re-open the original race
   * window.
   *
   * [Example]
   *
   * ocfs2_meta_lock()
   *  ocfs2_cluster_lock()
   *   set BUSY
   *   set PENDING
   *   drop l_lock
   *   ocfs2_dlm_lock()
   *    ocfs2_locking_ast()		ocfs2_downconvert_thread()
   *     clear PENDING			 ocfs2_unblock_lock()
   *					  take_l_lock
   *					  !BUSY
   *					  ocfs2_prepare_downconvert()
   *					   set BUSY
   *					   set PENDING
   *					  drop l_lock
   *   take l_lock
   *   clear PENDING
   *   drop l_lock
   *			<window>
   *					  ocfs2_dlm_lock()
   *
   * So as you can see, we now have a window where l_lock is not held,
   * PENDING is not set, and ocfs2_dlm_lock() has not been called.
   *
   * The core problem is that ocfs2_cluster_lock() has cleared the PENDING
   * set by ocfs2_prepare_downconvert().  That wasn't nice.
   *
   * To solve this we introduce l_pending_gen.  A call to
   * lockres_clear_pending() will only do so when it is passed a generation
   * number that matches the lockres.  lockres_set_pending() will return the
   * current generation number.  When ocfs2_cluster_lock() goes to clear
   * PENDING, it passes the generation it got from set_pending().  In our
   * example above, the generation numbers will *not* match.  Thus,
   * ocfs2_cluster_lock() will not clear the PENDING set by
   * ocfs2_prepare_downconvert().
   */
  
  /* Unlocked version for ocfs2_locking_ast() */
  static void __lockres_clear_pending(struct ocfs2_lock_res *lockres,
  				    unsigned int generation,
  				    struct ocfs2_super *osb)
  {
  	assert_spin_locked(&lockres->l_lock);
  
  	/*
  	 * The ast and locking functions can race us here.  The winner
  	 * will clear pending, the loser will not.
  	 */
  	if (!(lockres->l_flags & OCFS2_LOCK_PENDING) ||
  	    (lockres->l_pending_gen != generation))
  		return;
  
  	lockres_clear_flags(lockres, OCFS2_LOCK_PENDING);
  	lockres->l_pending_gen++;
  
  	/*
  	 * The downconvert thread may have skipped us because we
  	 * were PENDING.  Wake it up.
  	 */
  	if (lockres->l_flags & OCFS2_LOCK_BLOCKED)
  		ocfs2_wake_downconvert_thread(osb);
  }
  
  /* Locked version for callers of ocfs2_dlm_lock() */
  static void lockres_clear_pending(struct ocfs2_lock_res *lockres,
  				  unsigned int generation,
  				  struct ocfs2_super *osb)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	__lockres_clear_pending(lockres, generation, osb);
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  }
  
  static unsigned int lockres_set_pending(struct ocfs2_lock_res *lockres)
  {
  	assert_spin_locked(&lockres->l_lock);
  	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BUSY));
  
  	lockres_or_flags(lockres, OCFS2_LOCK_PENDING);
  
  	return lockres->l_pending_gen;
  }

  static void ocfs2_blocking_ast(struct ocfs2_dlm_lksb *lksb, int level)

  {

  	struct ocfs2_lock_res *lockres = ocfs2_lksb_to_lock_res(lksb);

  	struct ocfs2_super *osb = ocfs2_get_lockres_osb(lockres);

  	int needs_downconvert;
  	unsigned long flags;

  	BUG_ON(level <= DLM_LOCK_NL);

  	mlog(ML_BASTS, "BAST fired for lockres %s, blocking %d, level %d, "
  	     "type %s
  ", lockres->l_name, level, lockres->l_level,

  	     ocfs2_lock_type_string(lockres->l_type));

  	/*
  	 * We can skip the bast for locks which don't enable caching -
  	 * they'll be dropped at the earliest possible time anyway.
  	 */
  	if (lockres->l_flags & OCFS2_LOCK_NOCACHE)
  		return;

  	spin_lock_irqsave(&lockres->l_lock, flags);
  	needs_downconvert = ocfs2_generic_handle_bast(lockres, level);
  	if (needs_downconvert)
  		ocfs2_schedule_blocked_lock(osb, lockres);
  	spin_unlock_irqrestore(&lockres->l_lock, flags);

  	wake_up(&lockres->l_event);

  	ocfs2_wake_downconvert_thread(osb);

  }

  static void ocfs2_locking_ast(struct ocfs2_dlm_lksb *lksb)

  {

  	struct ocfs2_lock_res *lockres = ocfs2_lksb_to_lock_res(lksb);

  	struct ocfs2_super *osb = ocfs2_get_lockres_osb(lockres);

  	unsigned long flags;

  	int status;

  
  	spin_lock_irqsave(&lockres->l_lock, flags);

  	status = ocfs2_dlm_lock_status(&lockres->l_lksb);
  
  	if (status == -EAGAIN) {
  		lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
  		goto out;
  	}
  
  	if (status) {

  		mlog(ML_ERROR, "lockres %s: lksb status value of %d!
  ",

  		     lockres->l_name, status);

  		spin_unlock_irqrestore(&lockres->l_lock, flags);
  		return;
  	}

  	mlog(ML_BASTS, "AST fired for lockres %s, action %d, unlock %d, "
  	     "level %d => %d
  ", lockres->l_name, lockres->l_action,
  	     lockres->l_unlock_action, lockres->l_level, lockres->l_requested);

  	switch(lockres->l_action) {
  	case OCFS2_AST_ATTACH:
  		ocfs2_generic_handle_attach_action(lockres);

  		lockres_clear_flags(lockres, OCFS2_LOCK_LOCAL);

  		break;
  	case OCFS2_AST_CONVERT:
  		ocfs2_generic_handle_convert_action(lockres);
  		break;
  	case OCFS2_AST_DOWNCONVERT:
  		ocfs2_generic_handle_downconvert_action(lockres);
  		break;
  	default:

  		mlog(ML_ERROR, "lockres %s: AST fired with invalid action: %u, "
  		     "flags 0x%lx, unlock: %u
  ",

  		     lockres->l_name, lockres->l_action, lockres->l_flags,
  		     lockres->l_unlock_action);

  		BUG();
  	}

  out:

  	/* set it to something invalid so if we get called again we
  	 * can catch it. */
  	lockres->l_action = OCFS2_AST_INVALID;

  	/* Did we try to cancel this lock?  Clear that state */
  	if (lockres->l_unlock_action == OCFS2_UNLOCK_CANCEL_CONVERT)
  		lockres->l_unlock_action = OCFS2_UNLOCK_INVALID;
  
  	/*
  	 * We may have beaten the locking functions here.  We certainly
  	 * know that dlm_lock() has been called :-)
  	 * Because we can't have two lock calls in flight at once, we
  	 * can use lockres->l_pending_gen.
  	 */
  	__lockres_clear_pending(lockres, lockres->l_pending_gen,  osb);

  	wake_up(&lockres->l_event);

  	spin_unlock_irqrestore(&lockres->l_lock, flags);

  }

  static void ocfs2_unlock_ast(struct ocfs2_dlm_lksb *lksb, int error)
  {
  	struct ocfs2_lock_res *lockres = ocfs2_lksb_to_lock_res(lksb);
  	unsigned long flags;

  	mlog(ML_BASTS, "UNLOCK AST fired for lockres %s, action = %d
  ",
  	     lockres->l_name, lockres->l_unlock_action);

  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	if (error) {
  		mlog(ML_ERROR, "Dlm passes error %d for lock %s, "
  		     "unlock_action %d
  ", error, lockres->l_name,
  		     lockres->l_unlock_action);
  		spin_unlock_irqrestore(&lockres->l_lock, flags);

  		return;
  	}
  
  	switch(lockres->l_unlock_action) {
  	case OCFS2_UNLOCK_CANCEL_CONVERT:
  		mlog(0, "Cancel convert success for %s
  ", lockres->l_name);
  		lockres->l_action = OCFS2_AST_INVALID;
  		/* Downconvert thread may have requeued this lock, we
  		 * need to wake it. */
  		if (lockres->l_flags & OCFS2_LOCK_BLOCKED)
  			ocfs2_wake_downconvert_thread(ocfs2_get_lockres_osb(lockres));
  		break;
  	case OCFS2_UNLOCK_DROP_LOCK:
  		lockres->l_level = DLM_LOCK_IV;
  		break;
  	default:
  		BUG();
  	}
  
  	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
  	lockres->l_unlock_action = OCFS2_UNLOCK_INVALID;
  	wake_up(&lockres->l_event);
  	spin_unlock_irqrestore(&lockres->l_lock, flags);

  }
  
  /*
   * This is the filesystem locking protocol.  It provides the lock handling
   * hooks for the underlying DLM.  It has a maximum version number.
   * The version number allows interoperability with systems running at
   * the same major number and an equal or smaller minor number.
   *
   * Whenever the filesystem does new things with locks (adds or removes a
   * lock, orders them differently, does different things underneath a lock),
   * the version must be changed.  The protocol is negotiated when joining
   * the dlm domain.  A node may join the domain if its major version is
   * identical to all other nodes and its minor version is greater than
   * or equal to all other nodes.  When its minor version is greater than
   * the other nodes, it will run at the minor version specified by the
   * other nodes.
   *
   * If a locking change is made that will not be compatible with older
   * versions, the major number must be increased and the minor version set
   * to zero.  If a change merely adds a behavior that can be disabled when
   * speaking to older versions, the minor version must be increased.  If a
   * change adds a fully backwards compatible change (eg, LVB changes that
   * are just ignored by older versions), the version does not need to be
   * updated.
   */
  static struct ocfs2_locking_protocol lproto = {
  	.lp_max_version = {
  		.pv_major = OCFS2_LOCKING_PROTOCOL_MAJOR,
  		.pv_minor = OCFS2_LOCKING_PROTOCOL_MINOR,
  	},
  	.lp_lock_ast		= ocfs2_locking_ast,
  	.lp_blocking_ast	= ocfs2_blocking_ast,
  	.lp_unlock_ast		= ocfs2_unlock_ast,
  };
  
  void ocfs2_set_locking_protocol(void)
  {
  	ocfs2_stack_glue_set_max_proto_version(&lproto.lp_max_version);
  }

  static inline void ocfs2_recover_from_dlm_error(struct ocfs2_lock_res *lockres,
  						int convert)
  {
  	unsigned long flags;

  	spin_lock_irqsave(&lockres->l_lock, flags);
  	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);

  	lockres_clear_flags(lockres, OCFS2_LOCK_UPCONVERT_FINISHING);

  	if (convert)
  		lockres->l_action = OCFS2_AST_INVALID;
  	else
  		lockres->l_unlock_action = OCFS2_UNLOCK_INVALID;
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  	wake_up(&lockres->l_event);

  }
  
  /* Note: If we detect another process working on the lock (i.e.,
   * OCFS2_LOCK_BUSY), we'll bail out returning 0. It's up to the caller
   * to do the right thing in that case.
   */
  static int ocfs2_lock_create(struct ocfs2_super *osb,
  			     struct ocfs2_lock_res *lockres,
  			     int level,

  			     u32 dlm_flags)

  {
  	int ret = 0;

  	unsigned long flags;

  	unsigned int gen;

  	mlog(0, "lock %s, level = %d, flags = %u
  ", lockres->l_name, level,

  	     dlm_flags);
  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	if ((lockres->l_flags & OCFS2_LOCK_ATTACHED) ||
  	    (lockres->l_flags & OCFS2_LOCK_BUSY)) {
  		spin_unlock_irqrestore(&lockres->l_lock, flags);
  		goto bail;
  	}
  
  	lockres->l_action = OCFS2_AST_ATTACH;
  	lockres->l_requested = level;
  	lockres_or_flags(lockres, OCFS2_LOCK_BUSY);

  	gen = lockres_set_pending(lockres);

  	spin_unlock_irqrestore(&lockres->l_lock, flags);

  	ret = ocfs2_dlm_lock(osb->cconn,

  			     level,
  			     &lockres->l_lksb,
  			     dlm_flags,
  			     lockres->l_name,

  			     OCFS2_LOCK_ID_MAX_LEN - 1);

  	lockres_clear_pending(lockres, gen, osb);

  	if (ret) {
  		ocfs2_log_dlm_error("ocfs2_dlm_lock", ret, lockres);

  		ocfs2_recover_from_dlm_error(lockres, 1);
  	}

  	mlog(0, "lock %s, return from ocfs2_dlm_lock
  ", lockres->l_name);

  
  bail:

  	return ret;
  }
  
  static inline int ocfs2_check_wait_flag(struct ocfs2_lock_res *lockres,
  					int flag)
  {
  	unsigned long flags;
  	int ret;
  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	ret = lockres->l_flags & flag;
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  	return ret;
  }
  
  static inline void ocfs2_wait_on_busy_lock(struct ocfs2_lock_res *lockres)
  
  {
  	wait_event(lockres->l_event,
  		   !ocfs2_check_wait_flag(lockres, OCFS2_LOCK_BUSY));
  }
  
  static inline void ocfs2_wait_on_refreshing_lock(struct ocfs2_lock_res *lockres)
  
  {
  	wait_event(lockres->l_event,
  		   !ocfs2_check_wait_flag(lockres, OCFS2_LOCK_REFRESHING));
  }
  
  /* predict what lock level we'll be dropping down to on behalf
   * of another node, and return true if the currently wanted
   * level will be compatible with it. */
  static inline int ocfs2_may_continue_on_blocked_lock(struct ocfs2_lock_res *lockres,
  						     int wanted)
  {
  	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BLOCKED));
  
  	return wanted <= ocfs2_highest_compat_lock_level(lockres->l_blocking);
  }
  
  static void ocfs2_init_mask_waiter(struct ocfs2_mask_waiter *mw)
  {
  	INIT_LIST_HEAD(&mw->mw_item);
  	init_completion(&mw->mw_complete);

  	ocfs2_init_start_time(mw);

  }
  
  static int ocfs2_wait_for_mask(struct ocfs2_mask_waiter *mw)
  {
  	wait_for_completion(&mw->mw_complete);
  	/* Re-arm the completion in case we want to wait on it again */

  	reinit_completion(&mw->mw_complete);

  	return mw->mw_status;
  }
  
  static void lockres_add_mask_waiter(struct ocfs2_lock_res *lockres,
  				    struct ocfs2_mask_waiter *mw,
  				    unsigned long mask,
  				    unsigned long goal)
  {
  	BUG_ON(!list_empty(&mw->mw_item));
  
  	assert_spin_locked(&lockres->l_lock);
  
  	list_add_tail(&mw->mw_item, &lockres->l_mask_waiters);
  	mw->mw_mask = mask;
  	mw->mw_goal = goal;
  }
  
  /* returns 0 if the mw that was removed was already satisfied, -EBUSY
   * if the mask still hadn't reached its goal */

  static int __lockres_remove_mask_waiter(struct ocfs2_lock_res *lockres,

  				      struct ocfs2_mask_waiter *mw)
  {

  	int ret = 0;

  	assert_spin_locked(&lockres->l_lock);

  	if (!list_empty(&mw->mw_item)) {
  		if ((lockres->l_flags & mw->mw_mask) != mw->mw_goal)
  			ret = -EBUSY;
  
  		list_del_init(&mw->mw_item);
  		init_completion(&mw->mw_complete);
  	}

  
  	return ret;
  }
  
  static int lockres_remove_mask_waiter(struct ocfs2_lock_res *lockres,
  				      struct ocfs2_mask_waiter *mw)
  {
  	unsigned long flags;
  	int ret = 0;
  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	ret = __lockres_remove_mask_waiter(lockres, mw);

  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  	return ret;
  
  }

  static int ocfs2_wait_for_mask_interruptible(struct ocfs2_mask_waiter *mw,
  					     struct ocfs2_lock_res *lockres)
  {
  	int ret;
  
  	ret = wait_for_completion_interruptible(&mw->mw_complete);
  	if (ret)
  		lockres_remove_mask_waiter(lockres, mw);
  	else
  		ret = mw->mw_status;
  	/* Re-arm the completion in case we want to wait on it again */

  	reinit_completion(&mw->mw_complete);

  	return ret;
  }

  static int __ocfs2_cluster_lock(struct ocfs2_super *osb,
  				struct ocfs2_lock_res *lockres,
  				int level,
  				u32 lkm_flags,
  				int arg_flags,
  				int l_subclass,
  				unsigned long caller_ip)

  {
  	struct ocfs2_mask_waiter mw;

  	int wait, catch_signals = !(osb->s_mount_opt & OCFS2_MOUNT_NOINTR);
  	int ret = 0; /* gcc doesn't realize wait = 1 guarantees ret is set */
  	unsigned long flags;

  	unsigned int gen;

  	int noqueue_attempted = 0;

  	int dlm_locked = 0;

  	int kick_dc = 0;

  	if (!(lockres->l_flags & OCFS2_LOCK_INITIALIZED)) {
  		mlog_errno(-EINVAL);
  		return -EINVAL;
  	}

  	ocfs2_init_mask_waiter(&mw);

  	if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB)

  		lkm_flags |= DLM_LKF_VALBLK;

  again:
  	wait = 0;

  	spin_lock_irqsave(&lockres->l_lock, flags);

  	if (catch_signals && signal_pending(current)) {
  		ret = -ERESTARTSYS;

  		goto unlock;

  	}

  	mlog_bug_on_msg(lockres->l_flags & OCFS2_LOCK_FREEING,
  			"Cluster lock called on freeing lockres %s! flags "
  			"0x%lx
  ", lockres->l_name, lockres->l_flags);
  
  	/* We only compare against the currently granted level
  	 * here. If the lock is blocked waiting on a downconvert,
  	 * we'll get caught below. */
  	if (lockres->l_flags & OCFS2_LOCK_BUSY &&
  	    level > lockres->l_level) {
  		/* is someone sitting in dlm_lock? If so, wait on
  		 * them. */
  		lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
  		wait = 1;
  		goto unlock;
  	}

  	if (lockres->l_flags & OCFS2_LOCK_UPCONVERT_FINISHING) {
  		/*
  		 * We've upconverted. If the lock now has a level we can
  		 * work with, we take it. If, however, the lock is not at the
  		 * required level, we go thru the full cycle. One way this could
  		 * happen is if a process requesting an upconvert to PR is
  		 * closely followed by another requesting upconvert to an EX.
  		 * If the process requesting EX lands here, we want it to
  		 * continue attempting to upconvert and let the process
  		 * requesting PR take the lock.
  		 * If multiple processes request upconvert to PR, the first one
  		 * here will take the lock. The others will have to go thru the
  		 * OCFS2_LOCK_BLOCKED check to ensure that there is no pending
  		 * downconvert request.
  		 */
  		if (level <= lockres->l_level)
  			goto update_holders;
  	}

  	if (lockres->l_flags & OCFS2_LOCK_BLOCKED &&
  	    !ocfs2_may_continue_on_blocked_lock(lockres, level)) {
  		/* is the lock is currently blocked on behalf of
  		 * another node */
  		lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BLOCKED, 0);
  		wait = 1;
  		goto unlock;
  	}
  
  	if (level > lockres->l_level) {

  		if (noqueue_attempted > 0) {
  			ret = -EAGAIN;
  			goto unlock;
  		}
  		if (lkm_flags & DLM_LKF_NOQUEUE)
  			noqueue_attempted = 1;

  		if (lockres->l_action != OCFS2_AST_INVALID)
  			mlog(ML_ERROR, "lockres %s has action %u pending
  ",
  			     lockres->l_name, lockres->l_action);

  		if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED)) {
  			lockres->l_action = OCFS2_AST_ATTACH;

  			lkm_flags &= ~DLM_LKF_CONVERT;

  		} else {
  			lockres->l_action = OCFS2_AST_CONVERT;

  			lkm_flags |= DLM_LKF_CONVERT;

  		}

  		lockres->l_requested = level;
  		lockres_or_flags(lockres, OCFS2_LOCK_BUSY);

  		gen = lockres_set_pending(lockres);

  		spin_unlock_irqrestore(&lockres->l_lock, flags);

  		BUG_ON(level == DLM_LOCK_IV);
  		BUG_ON(level == DLM_LOCK_NL);

  		mlog(ML_BASTS, "lockres %s, convert from %d to %d
  ",

  		     lockres->l_name, lockres->l_level, level);
  
  		/* call dlm_lock to upgrade lock now */

  		ret = ocfs2_dlm_lock(osb->cconn,

  				     level,
  				     &lockres->l_lksb,
  				     lkm_flags,
  				     lockres->l_name,

  				     OCFS2_LOCK_ID_MAX_LEN - 1);

  		lockres_clear_pending(lockres, gen, osb);

  		if (ret) {
  			if (!(lkm_flags & DLM_LKF_NOQUEUE) ||
  			    (ret != -EAGAIN)) {

  				ocfs2_log_dlm_error("ocfs2_dlm_lock",

  						    ret, lockres);

  			}
  			ocfs2_recover_from_dlm_error(lockres, 1);
  			goto out;
  		}

  		dlm_locked = 1;

  		mlog(0, "lock %s, successful return from ocfs2_dlm_lock
  ",

  		     lockres->l_name);
  
  		/* At this point we've gone inside the dlm and need to
  		 * complete our work regardless. */
  		catch_signals = 0;
  
  		/* wait for busy to clear and carry on */
  		goto again;
  	}

  update_holders:

  	/* Ok, if we get here then we're good to go. */
  	ocfs2_inc_holders(lockres, level);
  
  	ret = 0;
  unlock:

  	lockres_clear_flags(lockres, OCFS2_LOCK_UPCONVERT_FINISHING);

  	/* ocfs2_unblock_lock reques on seeing OCFS2_LOCK_UPCONVERT_FINISHING */
  	kick_dc = (lockres->l_flags & OCFS2_LOCK_BLOCKED);

  	spin_unlock_irqrestore(&lockres->l_lock, flags);

  	if (kick_dc)
  		ocfs2_wake_downconvert_thread(osb);

  out:
  	/*
  	 * This is helping work around a lock inversion between the page lock
  	 * and dlm locks.  One path holds the page lock while calling aops
  	 * which block acquiring dlm locks.  The voting thread holds dlm
  	 * locks while acquiring page locks while down converting data locks.
  	 * This block is helping an aop path notice the inversion and back
  	 * off to unlock its page lock before trying the dlm lock again.
  	 */
  	if (wait && arg_flags & OCFS2_LOCK_NONBLOCK &&
  	    mw.mw_mask & (OCFS2_LOCK_BUSY|OCFS2_LOCK_BLOCKED)) {
  		wait = 0;

  		spin_lock_irqsave(&lockres->l_lock, flags);
  		if (__lockres_remove_mask_waiter(lockres, &mw)) {
  			if (dlm_locked)
  				lockres_or_flags(lockres,
  					OCFS2_LOCK_NONBLOCK_FINISHED);
  			spin_unlock_irqrestore(&lockres->l_lock, flags);

  			ret = -EAGAIN;

  		} else {
  			spin_unlock_irqrestore(&lockres->l_lock, flags);

  			goto again;

  		}

  	}
  	if (wait) {
  		ret = ocfs2_wait_for_mask(&mw);
  		if (ret == 0)
  			goto again;
  		mlog_errno(ret);
  	}

  	ocfs2_update_lock_stats(lockres, level, &mw, ret);

  #ifdef CONFIG_DEBUG_LOCK_ALLOC
  	if (!ret && lockres->l_lockdep_map.key != NULL) {
  		if (level == DLM_LOCK_PR)
  			rwsem_acquire_read(&lockres->l_lockdep_map, l_subclass,
  				!!(arg_flags & OCFS2_META_LOCK_NOQUEUE),
  				caller_ip);
  		else
  			rwsem_acquire(&lockres->l_lockdep_map, l_subclass,
  				!!(arg_flags & OCFS2_META_LOCK_NOQUEUE),
  				caller_ip);
  	}
  #endif

  	return ret;
  }

  static inline int ocfs2_cluster_lock(struct ocfs2_super *osb,
  				     struct ocfs2_lock_res *lockres,
  				     int level,
  				     u32 lkm_flags,
  				     int arg_flags)
  {
  	return __ocfs2_cluster_lock(osb, lockres, level, lkm_flags, arg_flags,
  				    0, _RET_IP_);
  }
  
  
  static void __ocfs2_cluster_unlock(struct ocfs2_super *osb,
  				   struct ocfs2_lock_res *lockres,
  				   int level,
  				   unsigned long caller_ip)

  {
  	unsigned long flags;

  	spin_lock_irqsave(&lockres->l_lock, flags);
  	ocfs2_dec_holders(lockres, level);

  	ocfs2_downconvert_on_unlock(osb, lockres);

  	spin_unlock_irqrestore(&lockres->l_lock, flags);

  #ifdef CONFIG_DEBUG_LOCK_ALLOC
  	if (lockres->l_lockdep_map.key != NULL)
  		rwsem_release(&lockres->l_lockdep_map, 1, caller_ip);
  #endif

  }

  static int ocfs2_create_new_lock(struct ocfs2_super *osb,
  				 struct ocfs2_lock_res *lockres,
  				 int ex,
  				 int local)

  {

  	int level =  ex ? DLM_LOCK_EX : DLM_LOCK_PR;

  	unsigned long flags;

  	u32 lkm_flags = local ? DLM_LKF_LOCAL : 0;

  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	BUG_ON(lockres->l_flags & OCFS2_LOCK_ATTACHED);
  	lockres_or_flags(lockres, OCFS2_LOCK_LOCAL);
  	spin_unlock_irqrestore(&lockres->l_lock, flags);

  	return ocfs2_lock_create(osb, lockres, level, lkm_flags);

  }
  
  /* Grants us an EX lock on the data and metadata resources, skipping
   * the normal cluster directory lookup. Use this ONLY on newly created
   * inodes which other nodes can't possibly see, and which haven't been
   * hashed in the inode hash yet. This can give us a good performance
   * increase as it'll skip the network broadcast normally associated
   * with creating a new lock resource. */
  int ocfs2_create_new_inode_locks(struct inode *inode)
  {
  	int ret;

  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

  	BUG_ON(!ocfs2_inode_is_new(inode));

  	mlog(0, "Inode %llu
  ", (unsigned long long)OCFS2_I(inode)->ip_blkno);

  
  	/* NOTE: That we don't increment any of the holder counts, nor
  	 * do we add anything to a journal handle. Since this is
  	 * supposed to be a new inode which the cluster doesn't know
  	 * about yet, there is no need to.  As far as the LVB handling
  	 * is concerned, this is basically like acquiring an EX lock
  	 * on a resource which has an invalid one -- we'll set it
  	 * valid when we release the EX. */

  	ret = ocfs2_create_new_lock(osb, &OCFS2_I(inode)->ip_rw_lockres, 1, 1);

  	if (ret) {
  		mlog_errno(ret);
  		goto bail;
  	}

  	/*

  	 * We don't want to use DLM_LKF_LOCAL on a meta data lock as they

  	 * don't use a generation in their lock names.
  	 */

  	ret = ocfs2_create_new_lock(osb, &OCFS2_I(inode)->ip_inode_lockres, 1, 0);

  	if (ret) {
  		mlog_errno(ret);
  		goto bail;
  	}

  	ret = ocfs2_create_new_lock(osb, &OCFS2_I(inode)->ip_open_lockres, 0, 0);

  	if (ret)

  		mlog_errno(ret);

  bail:

  	return ret;
  }
  
  int ocfs2_rw_lock(struct inode *inode, int write)
  {
  	int status, level;
  	struct ocfs2_lock_res *lockres;

  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

  	mlog(0, "inode %llu take %s RW lock
  ",
  	     (unsigned long long)OCFS2_I(inode)->ip_blkno,

  	     write ? "EXMODE" : "PRMODE");

  	if (ocfs2_mount_local(osb))

  		return 0;

  	lockres = &OCFS2_I(inode)->ip_rw_lockres;

  	level = write ? DLM_LOCK_EX : DLM_LOCK_PR;

  
  	status = ocfs2_cluster_lock(OCFS2_SB(inode->i_sb), lockres, level, 0,
  				    0);
  	if (status < 0)
  		mlog_errno(status);

  	return status;
  }
  
  void ocfs2_rw_unlock(struct inode *inode, int write)
  {

  	int level = write ? DLM_LOCK_EX : DLM_LOCK_PR;

  	struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_rw_lockres;

  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

  	mlog(0, "inode %llu drop %s RW lock
  ",
  	     (unsigned long long)OCFS2_I(inode)->ip_blkno,

  	     write ? "EXMODE" : "PRMODE");

  	if (!ocfs2_mount_local(osb))
  		ocfs2_cluster_unlock(OCFS2_SB(inode->i_sb), lockres, level);

  }

  /*
   * ocfs2_open_lock always get PR mode lock.
   */
  int ocfs2_open_lock(struct inode *inode)
  {
  	int status = 0;
  	struct ocfs2_lock_res *lockres;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

  	mlog(0, "inode %llu take PRMODE open lock
  ",
  	     (unsigned long long)OCFS2_I(inode)->ip_blkno);

  	if (ocfs2_is_hard_readonly(osb) || ocfs2_mount_local(osb))

  		goto out;
  
  	lockres = &OCFS2_I(inode)->ip_open_lockres;
  
  	status = ocfs2_cluster_lock(OCFS2_SB(inode->i_sb), lockres,

  				    DLM_LOCK_PR, 0, 0);

  	if (status < 0)
  		mlog_errno(status);
  
  out:

  	return status;
  }
  
  int ocfs2_try_open_lock(struct inode *inode, int write)
  {
  	int status = 0, level;
  	struct ocfs2_lock_res *lockres;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

  	mlog(0, "inode %llu try to take %s open lock
  ",
  	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
  	     write ? "EXMODE" : "PRMODE");

  	if (ocfs2_is_hard_readonly(osb)) {
  		if (write)
  			status = -EROFS;
  		goto out;
  	}

  	if (ocfs2_mount_local(osb))
  		goto out;
  
  	lockres = &OCFS2_I(inode)->ip_open_lockres;

  	level = write ? DLM_LOCK_EX : DLM_LOCK_PR;

  
  	/*
  	 * The file system may already holding a PRMODE/EXMODE open lock.

  	 * Since we pass DLM_LKF_NOQUEUE, the request won't block waiting on

  	 * other nodes and the -EAGAIN will indicate to the caller that
  	 * this inode is still in use.
  	 */
  	status = ocfs2_cluster_lock(OCFS2_SB(inode->i_sb), lockres,

  				    level, DLM_LKF_NOQUEUE, 0);

  
  out:

  	return status;
  }
  
  /*
   * ocfs2_open_unlock unlock PR and EX mode open locks.
   */
  void ocfs2_open_unlock(struct inode *inode)
  {
  	struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_open_lockres;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

  	mlog(0, "inode %llu drop open lock
  ",
  	     (unsigned long long)OCFS2_I(inode)->ip_blkno);
  
  	if (ocfs2_mount_local(osb))
  		goto out;
  
  	if(lockres->l_ro_holders)
  		ocfs2_cluster_unlock(OCFS2_SB(inode->i_sb), lockres,

  				     DLM_LOCK_PR);

  	if(lockres->l_ex_holders)
  		ocfs2_cluster_unlock(OCFS2_SB(inode->i_sb), lockres,

  				     DLM_LOCK_EX);

  
  out:

  	return;

  }

  static int ocfs2_flock_handle_signal(struct ocfs2_lock_res *lockres,
  				     int level)
  {
  	int ret;
  	struct ocfs2_super *osb = ocfs2_get_lockres_osb(lockres);
  	unsigned long flags;
  	struct ocfs2_mask_waiter mw;
  
  	ocfs2_init_mask_waiter(&mw);
  
  retry_cancel:
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	if (lockres->l_flags & OCFS2_LOCK_BUSY) {
  		ret = ocfs2_prepare_cancel_convert(osb, lockres);
  		if (ret) {
  			spin_unlock_irqrestore(&lockres->l_lock, flags);
  			ret = ocfs2_cancel_convert(osb, lockres);
  			if (ret < 0) {
  				mlog_errno(ret);
  				goto out;
  			}
  			goto retry_cancel;
  		}
  		lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
  		spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  		ocfs2_wait_for_mask(&mw);
  		goto retry_cancel;
  	}
  
  	ret = -ERESTARTSYS;
  	/*
  	 * We may still have gotten the lock, in which case there's no
  	 * point to restarting the syscall.
  	 */
  	if (lockres->l_level == level)
  		ret = 0;
  
  	mlog(0, "Cancel returning %d. flags: 0x%lx, level: %d, act: %d
  ", ret,
  	     lockres->l_flags, lockres->l_level, lockres->l_action);
  
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  out:
  	return ret;
  }
  
  /*
   * ocfs2_file_lock() and ocfs2_file_unlock() map to a single pair of
   * flock() calls. The locking approach this requires is sufficiently
   * different from all other cluster lock types that we implement a

   * separate path to the "low-level" dlm calls. In particular:

   *
   * - No optimization of lock levels is done - we take at exactly
   *   what's been requested.
   *
   * - No lock caching is employed. We immediately downconvert to
   *   no-lock at unlock time. This also means flock locks never go on
   *   the blocking list).
   *
   * - Since userspace can trivially deadlock itself with flock, we make
   *   sure to allow cancellation of a misbehaving applications flock()
   *   request.
   *
   * - Access to any flock lockres doesn't require concurrency, so we
   *   can simplify the code by requiring the caller to guarantee
   *   serialization of dlmglue flock calls.
   */
  int ocfs2_file_lock(struct file *file, int ex, int trylock)
  {

  	int ret, level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
  	unsigned int lkm_flags = trylock ? DLM_LKF_NOQUEUE : 0;

  	unsigned long flags;
  	struct ocfs2_file_private *fp = file->private_data;
  	struct ocfs2_lock_res *lockres = &fp->fp_flock;
  	struct ocfs2_super *osb = OCFS2_SB(file->f_mapping->host->i_sb);
  	struct ocfs2_mask_waiter mw;
  
  	ocfs2_init_mask_waiter(&mw);
  
  	if ((lockres->l_flags & OCFS2_LOCK_BUSY) ||

  	    (lockres->l_level > DLM_LOCK_NL)) {

  		mlog(ML_ERROR,
  		     "File lock \"%s\" has busy or locked state: flags: 0x%lx, "
  		     "level: %u
  ", lockres->l_name, lockres->l_flags,
  		     lockres->l_level);
  		return -EINVAL;
  	}
  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED)) {
  		lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
  		spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  		/*
  		 * Get the lock at NLMODE to start - that way we
  		 * can cancel the upconvert request if need be.
  		 */

  		ret = ocfs2_lock_create(osb, lockres, DLM_LOCK_NL, 0);

  		if (ret < 0) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		ret = ocfs2_wait_for_mask(&mw);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  		spin_lock_irqsave(&lockres->l_lock, flags);
  	}
  
  	lockres->l_action = OCFS2_AST_CONVERT;

  	lkm_flags |= DLM_LKF_CONVERT;

  	lockres->l_requested = level;
  	lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
  
  	lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
  	spin_unlock_irqrestore(&lockres->l_lock, flags);

  	ret = ocfs2_dlm_lock(osb->cconn, level, &lockres->l_lksb, lkm_flags,

  			     lockres->l_name, OCFS2_LOCK_ID_MAX_LEN - 1);

  	if (ret) {
  		if (!trylock || (ret != -EAGAIN)) {

  			ocfs2_log_dlm_error("ocfs2_dlm_lock", ret, lockres);

  			ret = -EINVAL;
  		}
  
  		ocfs2_recover_from_dlm_error(lockres, 1);
  		lockres_remove_mask_waiter(lockres, &mw);
  		goto out;
  	}
  
  	ret = ocfs2_wait_for_mask_interruptible(&mw, lockres);
  	if (ret == -ERESTARTSYS) {
  		/*
  		 * Userspace can cause deadlock itself with
  		 * flock(). Current behavior locally is to allow the
  		 * deadlock, but abort the system call if a signal is
  		 * received. We follow this example, otherwise a
  		 * poorly written program could sit in kernel until
  		 * reboot.
  		 *
  		 * Handling this is a bit more complicated for Ocfs2
  		 * though. We can't exit this function with an
  		 * outstanding lock request, so a cancel convert is
  		 * required. We intentionally overwrite 'ret' - if the
  		 * cancel fails and the lock was granted, it's easier

  		 * to just bubble success back up to the user.

  		 */
  		ret = ocfs2_flock_handle_signal(lockres, level);

  	} else if (!ret && (level > lockres->l_level)) {
  		/* Trylock failed asynchronously */
  		BUG_ON(!trylock);
  		ret = -EAGAIN;

  	}
  
  out:
  
  	mlog(0, "Lock: \"%s\" ex: %d, trylock: %d, returns: %d
  ",
  	     lockres->l_name, ex, trylock, ret);
  	return ret;
  }
  
  void ocfs2_file_unlock(struct file *file)
  {
  	int ret;

  	unsigned int gen;

  	unsigned long flags;
  	struct ocfs2_file_private *fp = file->private_data;
  	struct ocfs2_lock_res *lockres = &fp->fp_flock;
  	struct ocfs2_super *osb = OCFS2_SB(file->f_mapping->host->i_sb);
  	struct ocfs2_mask_waiter mw;
  
  	ocfs2_init_mask_waiter(&mw);
  
  	if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED))
  		return;

  	if (lockres->l_level == DLM_LOCK_NL)

  		return;
  
  	mlog(0, "Unlock: \"%s\" flags: 0x%lx, level: %d, act: %d
  ",
  	     lockres->l_name, lockres->l_flags, lockres->l_level,
  	     lockres->l_action);
  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	/*
  	 * Fake a blocking ast for the downconvert code.
  	 */
  	lockres_or_flags(lockres, OCFS2_LOCK_BLOCKED);

  	lockres->l_blocking = DLM_LOCK_EX;

  	gen = ocfs2_prepare_downconvert(lockres, DLM_LOCK_NL);

  	lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
  	spin_unlock_irqrestore(&lockres->l_lock, flags);

  	ret = ocfs2_downconvert_lock(osb, lockres, DLM_LOCK_NL, 0, gen);

  	if (ret) {
  		mlog_errno(ret);
  		return;
  	}
  
  	ret = ocfs2_wait_for_mask(&mw);
  	if (ret)
  		mlog_errno(ret);
  }

  static void ocfs2_downconvert_on_unlock(struct ocfs2_super *osb,
  					struct ocfs2_lock_res *lockres)

  {
  	int kick = 0;

  	/* If we know that another node is waiting on our lock, kick

  	 * the downconvert thread * pre-emptively when we reach a release

  	 * condition. */
  	if (lockres->l_flags & OCFS2_LOCK_BLOCKED) {
  		switch(lockres->l_blocking) {

  		case DLM_LOCK_EX:

  			if (!lockres->l_ex_holders && !lockres->l_ro_holders)
  				kick = 1;
  			break;

  		case DLM_LOCK_PR:

  			if (!lockres->l_ex_holders)
  				kick = 1;
  			break;
  		default:
  			BUG();
  		}
  	}
  
  	if (kick)

  		ocfs2_wake_downconvert_thread(osb);

  }

  #define OCFS2_SEC_BITS   34
  #define OCFS2_SEC_SHIFT  (64 - 34)
  #define OCFS2_NSEC_MASK  ((1ULL << OCFS2_SEC_SHIFT) - 1)
  
  /* LVB only has room for 64 bits of time here so we pack it for
   * now. */
  static u64 ocfs2_pack_timespec(struct timespec *spec)
  {
  	u64 res;
  	u64 sec = spec->tv_sec;
  	u32 nsec = spec->tv_nsec;
  
  	res = (sec << OCFS2_SEC_SHIFT) | (nsec & OCFS2_NSEC_MASK);
  
  	return res;
  }
  
  /* Call this with the lockres locked. I am reasonably sure we don't
   * need ip_lock in this function as anyone who would be changing those

   * values is supposed to be blocked in ocfs2_inode_lock right now. */

  static void __ocfs2_stuff_meta_lvb(struct inode *inode)
  {
  	struct ocfs2_inode_info *oi = OCFS2_I(inode);

  	struct ocfs2_lock_res *lockres = &oi->ip_inode_lockres;

  	struct ocfs2_meta_lvb *lvb;

  	lvb = ocfs2_dlm_lvb(&lockres->l_lksb);

  	/*
  	 * Invalidate the LVB of a deleted inode - this way other
  	 * nodes are forced to go to disk and discover the new inode
  	 * status.
  	 */
  	if (oi->ip_flags & OCFS2_INODE_DELETED) {
  		lvb->lvb_version = 0;
  		goto out;
  	}

  	lvb->lvb_version   = OCFS2_LVB_VERSION;

  	lvb->lvb_isize	   = cpu_to_be64(i_size_read(inode));
  	lvb->lvb_iclusters = cpu_to_be32(oi->ip_clusters);

  	lvb->lvb_iuid      = cpu_to_be32(i_uid_read(inode));
  	lvb->lvb_igid      = cpu_to_be32(i_gid_read(inode));

  	lvb->lvb_imode     = cpu_to_be16(inode->i_mode);
  	lvb->lvb_inlink    = cpu_to_be16(inode->i_nlink);
  	lvb->lvb_iatime_packed  =
  		cpu_to_be64(ocfs2_pack_timespec(&inode->i_atime));
  	lvb->lvb_ictime_packed =
  		cpu_to_be64(ocfs2_pack_timespec(&inode->i_ctime));
  	lvb->lvb_imtime_packed =
  		cpu_to_be64(ocfs2_pack_timespec(&inode->i_mtime));

  	lvb->lvb_iattr    = cpu_to_be32(oi->ip_attr);

  	lvb->lvb_idynfeatures = cpu_to_be16(oi->ip_dyn_features);

  	lvb->lvb_igeneration = cpu_to_be32(inode->i_generation);

  out:

  	mlog_meta_lvb(0, lockres);

  }
  
  static void ocfs2_unpack_timespec(struct timespec *spec,
  				  u64 packed_time)
  {
  	spec->tv_sec = packed_time >> OCFS2_SEC_SHIFT;
  	spec->tv_nsec = packed_time & OCFS2_NSEC_MASK;
  }
  
  static void ocfs2_refresh_inode_from_lvb(struct inode *inode)
  {
  	struct ocfs2_inode_info *oi = OCFS2_I(inode);

  	struct ocfs2_lock_res *lockres = &oi->ip_inode_lockres;

  	struct ocfs2_meta_lvb *lvb;

  	mlog_meta_lvb(0, lockres);

  	lvb = ocfs2_dlm_lvb(&lockres->l_lksb);

  
  	/* We're safe here without the lockres lock... */
  	spin_lock(&oi->ip_lock);
  	oi->ip_clusters = be32_to_cpu(lvb->lvb_iclusters);
  	i_size_write(inode, be64_to_cpu(lvb->lvb_isize));

  	oi->ip_attr = be32_to_cpu(lvb->lvb_iattr);

  	oi->ip_dyn_features = be16_to_cpu(lvb->lvb_idynfeatures);

  	ocfs2_set_inode_flags(inode);

  	/* fast-symlinks are a special case */
  	if (S_ISLNK(inode->i_mode) && !oi->ip_clusters)
  		inode->i_blocks = 0;
  	else

  		inode->i_blocks = ocfs2_inode_sector_count(inode);

  	i_uid_write(inode, be32_to_cpu(lvb->lvb_iuid));
  	i_gid_write(inode, be32_to_cpu(lvb->lvb_igid));

  	inode->i_mode    = be16_to_cpu(lvb->lvb_imode);

  	set_nlink(inode, be16_to_cpu(lvb->lvb_inlink));

  	ocfs2_unpack_timespec(&inode->i_atime,
  			      be64_to_cpu(lvb->lvb_iatime_packed));
  	ocfs2_unpack_timespec(&inode->i_mtime,
  			      be64_to_cpu(lvb->lvb_imtime_packed));
  	ocfs2_unpack_timespec(&inode->i_ctime,
  			      be64_to_cpu(lvb->lvb_ictime_packed));
  	spin_unlock(&oi->ip_lock);

  }

  static inline int ocfs2_meta_lvb_is_trustable(struct inode *inode,
  					      struct ocfs2_lock_res *lockres)

  {

  	struct ocfs2_meta_lvb *lvb = ocfs2_dlm_lvb(&lockres->l_lksb);

  	if (ocfs2_dlm_lvb_valid(&lockres->l_lksb)
  	    && lvb->lvb_version == OCFS2_LVB_VERSION

  	    && be32_to_cpu(lvb->lvb_igeneration) == inode->i_generation)

  		return 1;
  	return 0;
  }
  
  /* Determine whether a lock resource needs to be refreshed, and
   * arbitrate who gets to refresh it.
   *
   *   0 means no refresh needed.
   *
   *   > 0 means you need to refresh this and you MUST call
   *   ocfs2_complete_lock_res_refresh afterwards. */
  static int ocfs2_should_refresh_lock_res(struct ocfs2_lock_res *lockres)
  {
  	unsigned long flags;
  	int status = 0;

  refresh_check:
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	if (!(lockres->l_flags & OCFS2_LOCK_NEEDS_REFRESH)) {
  		spin_unlock_irqrestore(&lockres->l_lock, flags);
  		goto bail;
  	}
  
  	if (lockres->l_flags & OCFS2_LOCK_REFRESHING) {
  		spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  		ocfs2_wait_on_refreshing_lock(lockres);
  		goto refresh_check;
  	}
  
  	/* Ok, I'll be the one to refresh this lock. */
  	lockres_or_flags(lockres, OCFS2_LOCK_REFRESHING);
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  	status = 1;
  bail:

  	mlog(0, "status %d
  ", status);

  	return status;
  }
  
  /* If status is non zero, I'll mark it as not being in refresh
   * anymroe, but i won't clear the needs refresh flag. */
  static inline void ocfs2_complete_lock_res_refresh(struct ocfs2_lock_res *lockres,
  						   int status)
  {
  	unsigned long flags;

  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	lockres_clear_flags(lockres, OCFS2_LOCK_REFRESHING);
  	if (!status)
  		lockres_clear_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  	wake_up(&lockres->l_event);

  }
  
  /* may or may not return a bh if it went to disk. */

  static int ocfs2_inode_lock_update(struct inode *inode,

  				  struct buffer_head **bh)
  {
  	int status = 0;
  	struct ocfs2_inode_info *oi = OCFS2_I(inode);

  	struct ocfs2_lock_res *lockres = &oi->ip_inode_lockres;

  	struct ocfs2_dinode *fe;

  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

  	if (ocfs2_mount_local(osb))
  		goto bail;

  	spin_lock(&oi->ip_lock);
  	if (oi->ip_flags & OCFS2_INODE_DELETED) {

  		mlog(0, "Orphaned inode %llu was deleted while we "

  		     "were waiting on a lock. ip_flags = 0x%x
  ",

  		     (unsigned long long)oi->ip_blkno, oi->ip_flags);

  		spin_unlock(&oi->ip_lock);
  		status = -ENOENT;
  		goto bail;
  	}
  	spin_unlock(&oi->ip_lock);

  	if (!ocfs2_should_refresh_lock_res(lockres))
  		goto bail;

  
  	/* This will discard any caching information we might have had
  	 * for the inode metadata. */

  	ocfs2_metadata_cache_purge(INODE_CACHE(inode));

  	ocfs2_extent_map_trunc(inode, 0);

  	if (ocfs2_meta_lvb_is_trustable(inode, lockres)) {

  		mlog(0, "Trusting LVB on inode %llu
  ",
  		     (unsigned long long)oi->ip_blkno);

  		ocfs2_refresh_inode_from_lvb(inode);
  	} else {
  		/* Boo, we have to go to disk. */
  		/* read bh, cast, ocfs2_refresh_inode */

  		status = ocfs2_read_inode_block(inode, bh);

  		if (status < 0) {
  			mlog_errno(status);
  			goto bail_refresh;
  		}
  		fe = (struct ocfs2_dinode *) (*bh)->b_data;
  
  		/* This is a good chance to make sure we're not

  		 * locking an invalid object.  ocfs2_read_inode_block()
  		 * already checked that the inode block is sane.

  		 *
  		 * We bug on a stale inode here because we checked
  		 * above whether it was wiped from disk. The wiping
  		 * node provides a guarantee that we receive that
  		 * message and can mark the inode before dropping any
  		 * locks associated with it. */

  		mlog_bug_on_msg(inode->i_generation !=
  				le32_to_cpu(fe->i_generation),

  				"Invalid dinode %llu disk generation: %u "

  				"inode->i_generation: %u
  ",

  				(unsigned long long)oi->ip_blkno,
  				le32_to_cpu(fe->i_generation),

  				inode->i_generation);
  		mlog_bug_on_msg(le64_to_cpu(fe->i_dtime) ||
  				!(fe->i_flags & cpu_to_le32(OCFS2_VALID_FL)),

  				"Stale dinode %llu dtime: %llu flags: 0x%x
  ",
  				(unsigned long long)oi->ip_blkno,
  				(unsigned long long)le64_to_cpu(fe->i_dtime),

  				le32_to_cpu(fe->i_flags));
  
  		ocfs2_refresh_inode(inode, fe);

  		ocfs2_track_lock_refresh(lockres);

  	}
  
  	status = 0;
  bail_refresh:

  	ocfs2_complete_lock_res_refresh(lockres, status);

  bail:

  	return status;
  }
  
  static int ocfs2_assign_bh(struct inode *inode,
  			   struct buffer_head **ret_bh,
  			   struct buffer_head *passed_bh)
  {
  	int status;
  
  	if (passed_bh) {
  		/* Ok, the update went to disk for us, use the
  		 * returned bh. */
  		*ret_bh = passed_bh;
  		get_bh(*ret_bh);
  
  		return 0;
  	}

  	status = ocfs2_read_inode_block(inode, ret_bh);

  	if (status < 0)
  		mlog_errno(status);
  
  	return status;
  }
  
  /*
   * returns < 0 error if the callback will never be called, otherwise
   * the result of the lock will be communicated via the callback.
   */

  int ocfs2_inode_lock_full_nested(struct inode *inode,
  				 struct buffer_head **ret_bh,
  				 int ex,
  				 int arg_flags,
  				 int subclass)

  {

  	int status, level, acquired;
  	u32 dlm_flags;

  	struct ocfs2_lock_res *lockres = NULL;

  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  	struct buffer_head *local_bh = NULL;

  	mlog(0, "inode %llu, take %s META lock
  ",
  	     (unsigned long long)OCFS2_I(inode)->ip_blkno,

  	     ex ? "EXMODE" : "PRMODE");
  
  	status = 0;
  	acquired = 0;
  	/* We'll allow faking a readonly metadata lock for
  	 * rodevices. */
  	if (ocfs2_is_hard_readonly(osb)) {
  		if (ex)
  			status = -EROFS;

  		goto getbh;

  	}

  	if ((arg_flags & OCFS2_META_LOCK_GETBH) ||
  	    ocfs2_mount_local(osb))
  		goto update;

  	if (!(arg_flags & OCFS2_META_LOCK_RECOVERY))

  		ocfs2_wait_for_recovery(osb);

  	lockres = &OCFS2_I(inode)->ip_inode_lockres;

  	level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;

  	dlm_flags = 0;
  	if (arg_flags & OCFS2_META_LOCK_NOQUEUE)

  		dlm_flags |= DLM_LKF_NOQUEUE;

  	status = __ocfs2_cluster_lock(osb, lockres, level, dlm_flags,
  				      arg_flags, subclass, _RET_IP_);

  	if (status < 0) {

  		if (status != -EAGAIN)

  			mlog_errno(status);
  		goto bail;
  	}
  
  	/* Notify the error cleanup path to drop the cluster lock. */
  	acquired = 1;
  
  	/* We wait twice because a node may have died while we were in
  	 * the lower dlm layers. The second time though, we've
  	 * committed to owning this lock so we don't allow signals to
  	 * abort the operation. */
  	if (!(arg_flags & OCFS2_META_LOCK_RECOVERY))

  		ocfs2_wait_for_recovery(osb);

  update:

  	/*
  	 * We only see this flag if we're being called from
  	 * ocfs2_read_locked_inode(). It means we're locking an inode
  	 * which hasn't been populated yet, so clear the refresh flag
  	 * and let the caller handle it.
  	 */
  	if (inode->i_state & I_NEW) {
  		status = 0;

  		if (lockres)
  			ocfs2_complete_lock_res_refresh(lockres, 0);

  		goto bail;
  	}

  	/* This is fun. The caller may want a bh back, or it may

  	 * not. ocfs2_inode_lock_update definitely wants one in, but

  	 * may or may not read one, depending on what's in the
  	 * LVB. The result of all of this is that we've *only* gone to
  	 * disk if we have to, so the complexity is worthwhile. */

  	status = ocfs2_inode_lock_update(inode, &local_bh);

  	if (status < 0) {
  		if (status != -ENOENT)
  			mlog_errno(status);
  		goto bail;
  	}

  getbh:

  	if (ret_bh) {
  		status = ocfs2_assign_bh(inode, ret_bh, local_bh);
  		if (status < 0) {
  			mlog_errno(status);
  			goto bail;
  		}
  	}

  bail:
  	if (status < 0) {
  		if (ret_bh && (*ret_bh)) {
  			brelse(*ret_bh);
  			*ret_bh = NULL;
  		}
  		if (acquired)

  			ocfs2_inode_unlock(inode, ex);

  	}
  
  	if (local_bh)
  		brelse(local_bh);

  	return status;
  }
  
  /*

   * This is working around a lock inversion between tasks acquiring DLM
   * locks while holding a page lock and the downconvert thread which
   * blocks dlm lock acquiry while acquiring page locks.

   *
   * ** These _with_page variantes are only intended to be called from aop
   * methods that hold page locks and return a very specific *positive* error
   * code that aop methods pass up to the VFS -- test for errors with != 0. **
   *

   * The DLM is called such that it returns -EAGAIN if it would have
   * blocked waiting for the downconvert thread.  In that case we unlock
   * our page so the downconvert thread can make progress.  Once we've
   * done this we have to return AOP_TRUNCATED_PAGE so the aop method
   * that called us can bubble that back up into the VFS who will then
   * immediately retry the aop call.

   */

  int ocfs2_inode_lock_with_page(struct inode *inode,

  			      struct buffer_head **ret_bh,
  			      int ex,
  			      struct page *page)
  {
  	int ret;

  	ret = ocfs2_inode_lock_full(inode, ret_bh, ex, OCFS2_LOCK_NONBLOCK);

  	if (ret == -EAGAIN) {
  		unlock_page(page);

  		/*
  		 * If we can't get inode lock immediately, we should not return
  		 * directly here, since this will lead to a softlockup problem.
  		 * The method is to get a blocking lock and immediately unlock
  		 * before returning, this can avoid CPU resource waste due to
  		 * lots of retries, and benefits fairness in getting lock.
  		 */
  		if (ocfs2_inode_lock(inode, ret_bh, ex) == 0)
  			ocfs2_inode_unlock(inode, ex);

  		ret = AOP_TRUNCATED_PAGE;
  	}
  
  	return ret;
  }

  int ocfs2_inode_lock_atime(struct inode *inode,

  			  struct vfsmount *vfsmnt,
  			  int *level)
  {
  	int ret;

  	ret = ocfs2_inode_lock(inode, NULL, 0);

  	if (ret < 0) {
  		mlog_errno(ret);
  		return ret;
  	}
  
  	/*
  	 * If we should update atime, we will get EX lock,
  	 * otherwise we just get PR lock.
  	 */
  	if (ocfs2_should_update_atime(inode, vfsmnt)) {
  		struct buffer_head *bh = NULL;

  		ocfs2_inode_unlock(inode, 0);
  		ret = ocfs2_inode_lock(inode, &bh, 1);

  		if (ret < 0) {
  			mlog_errno(ret);
  			return ret;
  		}
  		*level = 1;
  		if (ocfs2_should_update_atime(inode, vfsmnt))
  			ocfs2_update_inode_atime(inode, bh);
  		if (bh)
  			brelse(bh);
  	} else
  		*level = 0;

  	return ret;
  }

  void ocfs2_inode_unlock(struct inode *inode,

  		       int ex)
  {

  	int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;

  	struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_inode_lockres;

  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

  	mlog(0, "inode %llu drop %s META lock
  ",
  	     (unsigned long long)OCFS2_I(inode)->ip_blkno,

  	     ex ? "EXMODE" : "PRMODE");

  	if (!ocfs2_is_hard_readonly(OCFS2_SB(inode->i_sb)) &&
  	    !ocfs2_mount_local(osb))

  		ocfs2_cluster_unlock(OCFS2_SB(inode->i_sb), lockres, level);

  }

  /*
   * This _tracker variantes are introduced to deal with the recursive cluster
   * locking issue. The idea is to keep track of a lock holder on the stack of
   * the current process. If there's a lock holder on the stack, we know the
   * task context is already protected by cluster locking. Currently, they're
   * used in some VFS entry routines.
   *
   * return < 0 on error, return == 0 if there's no lock holder on the stack
   * before this call, return == 1 if this call would be a recursive locking.
   */
  int ocfs2_inode_lock_tracker(struct inode *inode,
  			     struct buffer_head **ret_bh,
  			     int ex,
  			     struct ocfs2_lock_holder *oh)
  {
  	int status;
  	int arg_flags = 0, has_locked;
  	struct ocfs2_lock_res *lockres;
  
  	lockres = &OCFS2_I(inode)->ip_inode_lockres;
  	has_locked = ocfs2_is_locked_by_me(lockres);
  	/* Just get buffer head if the cluster lock has been taken */
  	if (has_locked)
  		arg_flags = OCFS2_META_LOCK_GETBH;
  
  	if (likely(!has_locked || ret_bh)) {
  		status = ocfs2_inode_lock_full(inode, ret_bh, ex, arg_flags);
  		if (status < 0) {
  			if (status != -ENOENT)
  				mlog_errno(status);
  			return status;
  		}
  	}
  	if (!has_locked)
  		ocfs2_add_holder(lockres, oh);
  
  	return has_locked;
  }
  
  void ocfs2_inode_unlock_tracker(struct inode *inode,
  				int ex,
  				struct ocfs2_lock_holder *oh,
  				int had_lock)
  {
  	struct ocfs2_lock_res *lockres;
  
  	lockres = &OCFS2_I(inode)->ip_inode_lockres;

  	/* had_lock means that the currect process already takes the cluster
  	 * lock previously. If had_lock is 1, we have nothing to do here, and
  	 * it will get unlocked where we got the lock.
  	 */

  	if (!had_lock) {
  		ocfs2_remove_holder(lockres, oh);
  		ocfs2_inode_unlock(inode, ex);
  	}
  }

  int ocfs2_orphan_scan_lock(struct ocfs2_super *osb, u32 *seqno)

  {
  	struct ocfs2_lock_res *lockres;
  	struct ocfs2_orphan_scan_lvb *lvb;

  	int status = 0;

  	if (ocfs2_is_hard_readonly(osb))
  		return -EROFS;
  
  	if (ocfs2_mount_local(osb))
  		return 0;

  	lockres = &osb->osb_orphan_scan.os_lockres;

  	status = ocfs2_cluster_lock(osb, lockres, DLM_LOCK_EX, 0, 0);

  	if (status < 0)
  		return status;
  
  	lvb = ocfs2_dlm_lvb(&lockres->l_lksb);

  	if (ocfs2_dlm_lvb_valid(&lockres->l_lksb) &&
  	    lvb->lvb_version == OCFS2_ORPHAN_LVB_VERSION)

  		*seqno = be32_to_cpu(lvb->lvb_os_seqno);

  	else
  		*seqno = osb->osb_orphan_scan.os_seqno + 1;

  	return status;
  }

  void ocfs2_orphan_scan_unlock(struct ocfs2_super *osb, u32 seqno)

  {
  	struct ocfs2_lock_res *lockres;
  	struct ocfs2_orphan_scan_lvb *lvb;

  	if (!ocfs2_is_hard_readonly(osb) && !ocfs2_mount_local(osb)) {
  		lockres = &osb->osb_orphan_scan.os_lockres;
  		lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
  		lvb->lvb_version = OCFS2_ORPHAN_LVB_VERSION;
  		lvb->lvb_os_seqno = cpu_to_be32(seqno);
  		ocfs2_cluster_unlock(osb, lockres, DLM_LOCK_EX);
  	}