text: /* -*- 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/crc32.h>
  #include <linux/kthread.h>
  #include <linux/pagemap.h>
  #include <linux/debugfs.h>
  #include <linux/seq_file.h>
  
  #include <cluster/heartbeat.h>
  #include <cluster/nodemanager.h>
  #include <cluster/tcp.h>
  
  #include <dlm/dlmapi.h>
  
  #define MLOG_MASK_PREFIX ML_DLM_GLUE
  #include <cluster/masklog.h>
  
  #include "ocfs2.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 "slot_map.h"
  #include "super.h"
  #include "uptodate.h"
  #include "vote.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;
  };
  
  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);
  
  /*
   * 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;
  };
  
  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);
  
  
  #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 = (struct ocfs2_meta_lvb *) lockres->l_lksb.lvb;
  
  	mlog(level, "LVB information for %s (called from %s:%u):\n",
  	     lockres->l_name, function, line);
  	mlog(level, "version: %u, clusters: %u, generation: 0x%x\n",
  	     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\n",
  	     (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\n", 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 (or "vote") 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_meta_lops = {
  	.get_osb	= ocfs2_get_inode_osb,
  	.check_downconvert = ocfs2_check_meta_downconvert,
  	.set_lvb	= ocfs2_set_meta_lvb,
  	.flags		= LOCK_TYPE_REQUIRES_REFRESH|LOCK_TYPE_USES_LVB,
  };
  
  static struct ocfs2_lock_res_ops ocfs2_inode_data_lops = {
  	.get_osb	= ocfs2_get_inode_osb,
  	.downconvert_worker = ocfs2_data_convert_worker,
  	.flags		= 0,
  };
  
  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_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 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_DATA ||
  		lockres->l_type == OCFS2_LOCK_TYPE_RW ||
  		lockres->l_type == OCFS2_LOCK_TYPE_OPEN;
  }
  
  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_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,
  			     int 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);
  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, _stat, _lockres) do {	\
  	mlog(ML_ERROR, "Dlm error \"%s\" while calling %s on "	\
  		"resource %s: %s\n", dlm_errname(_stat), _func,	\
  		_lockres->l_name, dlm_errmsg(_stat));		\
  } while (0)
  static void ocfs2_vote_on_unlock(struct ocfs2_super *osb,
  				 struct ocfs2_lock_res *lockres);
  static int ocfs2_meta_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 void ocfs2_build_lock_name(enum ocfs2_lock_type type,
  				  u64 blkno,
  				  u32 generation,
  				  char *name)
  {
  	int len;
  
  	mlog_entry_void();
  
  	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\n", name);
  
  	mlog_exit_void();
  }
  
  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\n", 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);
  }
  
  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         = LKM_IVMODE;
  	res->l_requested     = LKM_IVMODE;
  	res->l_blocking      = LKM_IVMODE;
  	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);
  }
  
  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);
  }
  
  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_meta_lops;
  			break;
  		case OCFS2_LOCK_TYPE_DATA:
  			ops = &ocfs2_inode_data_lops;
  			break;
  		case OCFS2_LOCK_TYPE_OPEN:
  			ops = &ocfs2_inode_open_lops;
  			break;
  		default:
  			mlog_bug_on_msg(1, "type: %d\n", 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 __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);
  }
  
  void ocfs2_lock_res_free(struct ocfs2_lock_res *res)
  {
  	mlog_entry_void();
  
  	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\n",
  			res->l_name);
  	mlog_bug_on_msg(!list_empty(&res->l_mask_waiters),
  			"Lockres %s has mask waiters pending\n",
  			res->l_name);
  	mlog_bug_on_msg(spin_is_locked(&res->l_lock),
  			"Lockres %s is locked\n",
  			res->l_name);
  	mlog_bug_on_msg(res->l_ro_holders,
  			"Lockres %s has %u ro holders\n",
  			res->l_name, res->l_ro_holders);
  	mlog_bug_on_msg(res->l_ex_holders,
  			"Lockres %s has %u ex holders\n",
  			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;
  	mlog_exit_void();
  }
  
  static inline void ocfs2_inc_holders(struct ocfs2_lock_res *lockres,
  				     int level)
  {
  	mlog_entry_void();
  
  	BUG_ON(!lockres);
  
  	switch(level) {
  	case LKM_EXMODE:
  		lockres->l_ex_holders++;
  		break;
  	case LKM_PRMODE:
  		lockres->l_ro_holders++;
  		break;
  	default:
  		BUG();
  	}
  
  	mlog_exit_void();
  }
  
  static inline void ocfs2_dec_holders(struct ocfs2_lock_res *lockres,
  				     int level)
  {
  	mlog_entry_void();
  
  	BUG_ON(!lockres);
  
  	switch(level) {
  	case LKM_EXMODE:
  		BUG_ON(!lockres->l_ex_holders);
  		lockres->l_ex_holders--;
  		break;
  	case LKM_PRMODE:
  		BUG_ON(!lockres->l_ro_holders);
  		lockres->l_ro_holders--;
  		break;
  	default:
  		BUG();
  	}
  	mlog_exit_void();
  }
  
  /* 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 = LKM_EXMODE;
  
  	if (level == LKM_EXMODE)
  		new_level = LKM_NLMODE;
  	else if (level == LKM_PRMODE)
  		new_level = LKM_PRMODE;
  	return new_level;
  }
  
  static void lockres_set_flags(struct ocfs2_lock_res *lockres,
  			      unsigned long newflags)
  {
  	struct list_head *pos, *tmp;
  	struct ocfs2_mask_waiter *mw;
  
   	assert_spin_locked(&lockres->l_lock);
  
  	lockres->l_flags = newflags;
  
  	list_for_each_safe(pos, tmp, &lockres->l_mask_waiters) {
  		mw = list_entry(pos, struct ocfs2_mask_waiter, 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)
  {
  	mlog_entry_void();
  
  	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 <= LKM_NLMODE);
  
  	lockres->l_level = lockres->l_requested;
  	if (lockres->l_level <=
  	    ocfs2_highest_compat_lock_level(lockres->l_blocking)) {
  		lockres->l_blocking = LKM_NLMODE;
  		lockres_clear_flags(lockres, OCFS2_LOCK_BLOCKED);
  	}
  	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
  
  	mlog_exit_void();
  }
  
  static inline void ocfs2_generic_handle_convert_action(struct ocfs2_lock_res *lockres)
  {
  	mlog_entry_void();
  
  	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 == LKM_NLMODE &&
  	    lockres->l_ops->flags & LOCK_TYPE_REQUIRES_REFRESH)
  		lockres_or_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
  
  	lockres->l_level = lockres->l_requested;
  	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
  
  	mlog_exit_void();
  }
  
  static inline void ocfs2_generic_handle_attach_action(struct ocfs2_lock_res *lockres)
  {
  	mlog_entry_void();
  
  	BUG_ON((!lockres->l_flags & OCFS2_LOCK_BUSY));
  	BUG_ON(lockres->l_flags & OCFS2_LOCK_ATTACHED);
  
  	if (lockres->l_requested > LKM_NLMODE &&
  	    !(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);
  
  	mlog_exit_void();
  }
  
  static int ocfs2_generic_handle_bast(struct ocfs2_lock_res *lockres,
  				     int level)
  {
  	int needs_downconvert = 0;
  	mlog_entry_void();
  
  	assert_spin_locked(&lockres->l_lock);
  
  	lockres_or_flags(lockres, OCFS2_LOCK_BLOCKED);
  
  	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_exit(needs_downconvert);
  	return needs_downconvert;
  }
  
  static void ocfs2_blocking_ast(void *opaque, int level)
  {
  	struct ocfs2_lock_res *lockres = opaque;
  	struct ocfs2_super *osb = ocfs2_get_lockres_osb(lockres);
  	int needs_downconvert;
  	unsigned long flags;
  
  	BUG_ON(level <= LKM_NLMODE);
  
  	mlog(0, "BAST fired for lockres %s, blocking %d, level %d type %s\n",
  	     lockres->l_name, level, lockres->l_level,
  	     ocfs2_lock_type_string(lockres->l_type));
  
  	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_kick_vote_thread(osb);
  }
  
  static void ocfs2_locking_ast(void *opaque)
  {
  	struct ocfs2_lock_res *lockres = opaque;
  	struct dlm_lockstatus *lksb = &lockres->l_lksb;
  	unsigned long flags;
  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  
  	if (lksb->status != DLM_NORMAL) {
  		mlog(ML_ERROR, "lockres %s: lksb status value of %u!\n",
  		     lockres->l_name, lksb->status);
  		spin_unlock_irqrestore(&lockres->l_lock, flags);
  		return;
  	}
  
  	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 "
  		     "lockres flags = 0x%lx, unlock action: %u\n",
  		     lockres->l_name, lockres->l_action, lockres->l_flags,
  		     lockres->l_unlock_action);
  		BUG();
  	}
  
  	/* set it to something invalid so if we get called again we
  	 * can catch it. */
  	lockres->l_action = OCFS2_AST_INVALID;
  
  	wake_up(&lockres->l_event);
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  }
  
  static inline void ocfs2_recover_from_dlm_error(struct ocfs2_lock_res *lockres,
  						int convert)
  {
  	unsigned long flags;
  
  	mlog_entry_void();
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
  	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);
  	mlog_exit_void();
  }
  
  /* 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,
  			     int dlm_flags)
  {
  	int ret = 0;
  	enum dlm_status status = DLM_NORMAL;
  	unsigned long flags;
  
  	mlog_entry_void();
  
  	mlog(0, "lock %s, level = %d, flags = %d\n", 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);
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  	status = dlmlock(osb->dlm,
  			 level,
  			 &lockres->l_lksb,
  			 dlm_flags,
  			 lockres->l_name,
  			 OCFS2_LOCK_ID_MAX_LEN - 1,
  			 ocfs2_locking_ast,
  			 lockres,
  			 ocfs2_blocking_ast);
  	if (status != DLM_NORMAL) {
  		ocfs2_log_dlm_error("dlmlock", status, lockres);
  		ret = -EINVAL;
  		ocfs2_recover_from_dlm_error(lockres, 1);
  	}
  
  	mlog(0, "lock %s, successfull return from dlmlock\n", lockres->l_name);
  
  bail:
  	mlog_exit(ret);
  	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);
  }
  
  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 */
  	INIT_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)
  {
  	unsigned long flags;
  	int ret = 0;
  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	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);
  	}
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  	return ret;
  
  }
  
  static int ocfs2_cluster_lock(struct ocfs2_super *osb,
  			      struct ocfs2_lock_res *lockres,
  			      int level,
  			      int lkm_flags,
  			      int arg_flags)
  {
  	struct ocfs2_mask_waiter mw;
  	enum dlm_status status;
  	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;
  
  	mlog_entry_void();
  
  	ocfs2_init_mask_waiter(&mw);
  
  	if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB)
  		lkm_flags |= LKM_VALBLK;
  
  again:
  	wait = 0;
  
  	if (catch_signals && signal_pending(current)) {
  		ret = -ERESTARTSYS;
  		goto out;
  	}
  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  
  	mlog_bug_on_msg(lockres->l_flags & OCFS2_LOCK_FREEING,
  			"Cluster lock called on freeing lockres %s! flags "
  			"0x%lx\n", 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_ATTACHED)) {
  		/* lock has not been created yet. */
  		spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  		ret = ocfs2_lock_create(osb, lockres, LKM_NLMODE, 0);
  		if (ret < 0) {
  			mlog_errno(ret);
  			goto out;
  		}
  		goto again;
  	}
  
  	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 (lockres->l_action != OCFS2_AST_INVALID)
  			mlog(ML_ERROR, "lockres %s has action %u pending\n",
  			     lockres->l_name, lockres->l_action);
  
  		lockres->l_action = OCFS2_AST_CONVERT;
  		lockres->l_requested = level;
  		lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
  		spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  		BUG_ON(level == LKM_IVMODE);
  		BUG_ON(level == LKM_NLMODE);
  
  		mlog(0, "lock %s, convert from %d to level = %d\n",
  		     lockres->l_name, lockres->l_level, level);
  
  		/* call dlm_lock to upgrade lock now */
  		status = dlmlock(osb->dlm,
  				 level,
  				 &lockres->l_lksb,
  				 lkm_flags|LKM_CONVERT,
  				 lockres->l_name,
  				 OCFS2_LOCK_ID_MAX_LEN - 1,
  				 ocfs2_locking_ast,
  				 lockres,
  				 ocfs2_blocking_ast);
  		if (status != DLM_NORMAL) {
  			if ((lkm_flags & LKM_NOQUEUE) &&
  			    (status == DLM_NOTQUEUED))
  				ret = -EAGAIN;
  			else {
  				ocfs2_log_dlm_error("dlmlock", status,
  						    lockres);
  				ret = -EINVAL;
  			}
  			ocfs2_recover_from_dlm_error(lockres, 1);
  			goto out;
  		}
  
  		mlog(0, "lock %s, successfull return from dlmlock\n",
  		     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;
  	}
  
  	/* Ok, if we get here then we're good to go. */
  	ocfs2_inc_holders(lockres, level);
  
  	ret = 0;
  unlock:
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  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;
  		if (lockres_remove_mask_waiter(lockres, &mw))
  			ret = -EAGAIN;
  		else
  			goto again;
  	}
  	if (wait) {
  		ret = ocfs2_wait_for_mask(&mw);
  		if (ret == 0)
  			goto again;
  		mlog_errno(ret);
  	}
  
  	mlog_exit(ret);
  	return ret;
  }
  
  static void ocfs2_cluster_unlock(struct ocfs2_super *osb,
  				 struct ocfs2_lock_res *lockres,
  				 int level)
  {
  	unsigned long flags;
  
  	mlog_entry_void();
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	ocfs2_dec_holders(lockres, level);
  	ocfs2_vote_on_unlock(osb, lockres);
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  	mlog_exit_void();
  }
  
  static int ocfs2_create_new_lock(struct ocfs2_super *osb,
  				 struct ocfs2_lock_res *lockres,
  				 int ex,
  				 int local)
  {
  	int level =  ex ? LKM_EXMODE : LKM_PRMODE;
  	unsigned long flags;
  	int lkm_flags = local ? LKM_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(!inode);
  	BUG_ON(!ocfs2_inode_is_new(inode));
  
  	mlog_entry_void();
  
  	mlog(0, "Inode %llu\n", (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 LKM_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_meta_lockres, 1, 0);
  	if (ret) {
  		mlog_errno(ret);
  		goto bail;
  	}
  
  	ret = ocfs2_create_new_lock(osb, &OCFS2_I(inode)->ip_data_lockres, 1, 1);
  	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);
  		goto bail;
  	}
  
  bail:
  	mlog_exit(ret);
  	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);
  
  	BUG_ON(!inode);
  
  	mlog_entry_void();
  
  	mlog(0, "inode %llu take %s RW lock\n",
  	     (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 ? LKM_EXMODE : LKM_PRMODE;
  
  	status = ocfs2_cluster_lock(OCFS2_SB(inode->i_sb), lockres, level, 0,
  				    0);
  	if (status < 0)
  		mlog_errno(status);
  
  	mlog_exit(status);
  	return status;
  }
  
  void ocfs2_rw_unlock(struct inode *inode, int write)
  {
  	int level = write ? LKM_EXMODE : LKM_PRMODE;
  	struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_rw_lockres;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  
  	mlog_entry_void();
  
  	mlog(0, "inode %llu drop %s RW lock\n",
  	     (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);
  
  	mlog_exit_void();
  }
  
  /*
   * 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);
  
  	BUG_ON(!inode);
  
  	mlog_entry_void();
  
  	mlog(0, "inode %llu take PRMODE open lock\n",
  	     (unsigned long long)OCFS2_I(inode)->ip_blkno);
  
  	if (ocfs2_mount_local(osb))
  		goto out;
  
  	lockres = &OCFS2_I(inode)->ip_open_lockres;
  
  	status = ocfs2_cluster_lock(OCFS2_SB(inode->i_sb), lockres,
  				    LKM_PRMODE, 0, 0);
  	if (status < 0)
  		mlog_errno(status);
  
  out:
  	mlog_exit(status);
  	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);
  
  	BUG_ON(!inode);
  
  	mlog_entry_void();
  
  	mlog(0, "inode %llu try to take %s open lock\n",
  	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
  	     write ? "EXMODE" : "PRMODE");
  
  	if (ocfs2_mount_local(osb))
  		goto out;
  
  	lockres = &OCFS2_I(inode)->ip_open_lockres;
  
  	level = write ? LKM_EXMODE : LKM_PRMODE;
  
  	/*
  	 * The file system may already holding a PRMODE/EXMODE open lock.
  	 * Since we pass LKM_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, LKM_NOQUEUE, 0);
  
  out:
  	mlog_exit(status);
  	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_entry_void();
  
  	mlog(0, "inode %llu drop open lock\n",
  	     (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,
  				     LKM_PRMODE);
  	if(lockres->l_ex_holders)
  		ocfs2_cluster_unlock(OCFS2_SB(inode->i_sb), lockres,
  				     LKM_EXMODE);
  
  out:
  	mlog_exit_void();
  }
  
  int ocfs2_data_lock_full(struct inode *inode,
  			 int write,
  			 int arg_flags)
  {
  	int status = 0, level;
  	struct ocfs2_lock_res *lockres;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  
  	BUG_ON(!inode);
  
  	mlog_entry_void();
  
  	mlog(0, "inode %llu take %s DATA lock\n",
  	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
  	     write ? "EXMODE" : "PRMODE");
  
  	/* We'll allow faking a readonly data lock for
  	 * rodevices. */
  	if (ocfs2_is_hard_readonly(OCFS2_SB(inode->i_sb))) {
  		if (write) {
  			status = -EROFS;
  			mlog_errno(status);
  		}
  		goto out;
  	}
  
  	if (ocfs2_mount_local(osb))
  		goto out;
  
  	lockres = &OCFS2_I(inode)->ip_data_lockres;
  
  	level = write ? LKM_EXMODE : LKM_PRMODE;
  
  	status = ocfs2_cluster_lock(OCFS2_SB(inode->i_sb), lockres, level,
  				    0, arg_flags);
  	if (status < 0 && status != -EAGAIN)
  		mlog_errno(status);
  
  out:
  	mlog_exit(status);
  	return status;
  }
  
  /* see ocfs2_meta_lock_with_page() */
  int ocfs2_data_lock_with_page(struct inode *inode,
  			      int write,
  			      struct page *page)
  {
  	int ret;
  
  	ret = ocfs2_data_lock_full(inode, write, OCFS2_LOCK_NONBLOCK);
  	if (ret == -EAGAIN) {
  		unlock_page(page);
  		if (ocfs2_data_lock(inode, write) == 0)
  			ocfs2_data_unlock(inode, write);
  		ret = AOP_TRUNCATED_PAGE;
  	}
  
  	return ret;
  }
  
  static void ocfs2_vote_on_unlock(struct ocfs2_super *osb,
  				 struct ocfs2_lock_res *lockres)
  {
  	int kick = 0;
  
  	mlog_entry_void();
  
  	/* If we know that another node is waiting on our lock, kick
  	 * the vote thread * pre-emptively when we reach a release
  	 * condition. */
  	if (lockres->l_flags & OCFS2_LOCK_BLOCKED) {
  		switch(lockres->l_blocking) {
  		case LKM_EXMODE:
  			if (!lockres->l_ex_holders && !lockres->l_ro_holders)
  				kick = 1;
  			break;
  		case LKM_PRMODE:
  			if (!lockres->l_ex_holders)
  				kick = 1;
  			break;
  		default:
  			BUG();
  		}
  	}
  
  	if (kick)
  		ocfs2_kick_vote_thread(osb);
  
  	mlog_exit_void();
  }
  
  void ocfs2_data_unlock(struct inode *inode,
  		       int write)
  {
  	int level = write ? LKM_EXMODE : LKM_PRMODE;
  	struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_data_lockres;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  
  	mlog_entry_void();
  
  	mlog(0, "inode %llu drop %s DATA lock\n",
  	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
  	     write ? "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);
  
  	mlog_exit_void();
  }
  
  #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_meta_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_meta_lockres;
  	struct ocfs2_meta_lvb *lvb;
  
  	mlog_entry_void();
  
  	lvb = (struct ocfs2_meta_lvb *) lockres->l_lksb.lvb;
  
  	/*
  	 * 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(inode->i_uid);
  	lvb->lvb_igid      = cpu_to_be32(inode->i_gid);
  	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_igeneration = cpu_to_be32(inode->i_generation);
  
  out:
  	mlog_meta_lvb(0, lockres);
  
  	mlog_exit_void();
  }
  
  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_meta_lockres;
  	struct ocfs2_meta_lvb *lvb;
  
  	mlog_entry_void();
  
  	mlog_meta_lvb(0, lockres);
  
  	lvb = (struct ocfs2_meta_lvb *) lockres->l_lksb.lvb;
  
  	/* 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);
  	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);
  
  	inode->i_uid     = be32_to_cpu(lvb->lvb_iuid);
  	inode->i_gid     = be32_to_cpu(lvb->lvb_igid);
  	inode->i_mode    = be16_to_cpu(lvb->lvb_imode);
  	inode->i_nlink   = 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);
  
  	mlog_exit_void();
  }
  
  static inline int ocfs2_meta_lvb_is_trustable(struct inode *inode,
  					      struct ocfs2_lock_res *lockres)
  {
  	struct ocfs2_meta_lvb *lvb = (struct ocfs2_meta_lvb *) lockres->l_lksb.lvb;
  
  	if (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;
  
  	mlog_entry_void();
  
  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_exit(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;
  	mlog_entry_void();
  
  	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);
  
  	mlog_exit_void();
  }
  
  /* may or may not return a bh if it went to disk. */
  static int ocfs2_meta_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_meta_lockres;
  	struct ocfs2_dinode *fe;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  
  	mlog_entry_void();
  
  	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\n",
  		     (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);
  
  	ocfs2_extent_map_trunc(inode, 0);
  
  	if (ocfs2_meta_lvb_is_trustable(inode, lockres)) {
  		mlog(0, "Trusting LVB on inode %llu\n",
  		     (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_block(OCFS2_SB(inode->i_sb), oi->ip_blkno,
  					  bh, OCFS2_BH_CACHED, inode);
  		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.
  		 *
  		 * 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. */
  		if (!OCFS2_IS_VALID_DINODE(fe)) {
  			OCFS2_RO_ON_INVALID_DINODE(inode->i_sb, fe);
  			status = -EIO;
  			goto bail_refresh;
  		}
  		mlog_bug_on_msg(inode->i_generation !=
  				le32_to_cpu(fe->i_generation),
  				"Invalid dinode %llu disk generation: %u "
  				"inode->i_generation: %u\n",
  				(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\n",
  				(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);
  	}
  
  	status = 0;
  bail_refresh:
  	ocfs2_complete_lock_res_refresh(lockres, status);
  bail:
  	mlog_exit(status);
  	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_block(OCFS2_SB(inode->i_sb),
  				  OCFS2_I(inode)->ip_blkno,
  				  ret_bh,
  				  OCFS2_BH_CACHED,
  				  inode);
  	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_meta_lock_full(struct inode *inode,
  			 struct buffer_head **ret_bh,
  			 int ex,
  			 int arg_flags)
  {
  	int status, level, dlm_flags, acquired;
  	struct ocfs2_lock_res *lockres = NULL;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  	struct buffer_head *local_bh = NULL;
  
  	BUG_ON(!inode);
  
  	mlog_entry_void();
  
  	mlog(0, "inode %llu, take %s META lock\n",
  	     (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 bail;
  	}
  
  	if (ocfs2_mount_local(osb))
  		goto local;
  
  	if (!(arg_flags & OCFS2_META_LOCK_RECOVERY))
  		wait_event(osb->recovery_event,
  			   ocfs2_node_map_is_empty(osb, &osb->recovery_map));
  
  	lockres = &OCFS2_I(inode)->ip_meta_lockres;
  	level = ex ? LKM_EXMODE : LKM_PRMODE;
  	dlm_flags = 0;
  	if (arg_flags & OCFS2_META_LOCK_NOQUEUE)
  		dlm_flags |= LKM_NOQUEUE;
  
  	status = ocfs2_cluster_lock(osb, lockres, level, dlm_flags, arg_flags);
  	if (status < 0) {
  		if (status != -EAGAIN && status != -EIOCBRETRY)
  			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))
  		wait_event(osb->recovery_event,
  			   ocfs2_node_map_is_empty(osb, &osb->recovery_map));
  
  local:
  	/*
  	 * 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_meta_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_meta_lock_update(inode, &local_bh);
  	if (status < 0) {
  		if (status != -ENOENT)
  			mlog_errno(status);
  		goto bail;
  	}
  
  	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_meta_unlock(inode, ex);
  	}
  
  	if (local_bh)
  		brelse(local_bh);
  
  	mlog_exit(status);
  	return status;
  }
  
  /*
   * This is working around a lock inversion between tasks acquiring DLM locks
   * while holding a page lock and the vote 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 vote thread.  In that case we unlock our page so the vote
   * 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.
   *
   * We do a blocking lock and immediate unlock before returning, though, so that
   * the lock has a great chance of being cached on this node by the time the VFS
   * calls back to retry the aop.    This has a potential to livelock as nodes
   * ping locks back and forth, but that's a risk we're willing to take to avoid
   * the lock inversion simply.
   */
  int ocfs2_meta_lock_with_page(struct inode *inode,
  			      struct buffer_head **ret_bh,
  			      int ex,
  			      struct page *page)
  {
  	int ret;
  
  	ret = ocfs2_meta_lock_full(inode, ret_bh, ex, OCFS2_LOCK_NONBLOCK);
  	if (ret == -EAGAIN) {
  		unlock_page(page);
  		if (ocfs2_meta_lock(inode, ret_bh, ex) == 0)
  			ocfs2_meta_unlock(inode, ex);
  		ret = AOP_TRUNCATED_PAGE;
  	}
  
  	return ret;
  }
  
  int ocfs2_meta_lock_atime(struct inode *inode,
  			  struct vfsmount *vfsmnt,
  			  int *level)
  {
  	int ret;
  
  	mlog_entry_void();
  	ret = ocfs2_meta_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_meta_unlock(inode, 0);
  		ret = ocfs2_meta_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;
  
  	mlog_exit(ret);
  	return ret;
  }
  
  void ocfs2_meta_unlock(struct inode *inode,
  		       int ex)
  {
  	int level = ex ? LKM_EXMODE : LKM_PRMODE;
  	struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_meta_lockres;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  
  	mlog_entry_void();
  
  	mlog(0, "inode %llu drop %s META lock\n",
  	     (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);
  
  	mlog_exit_void();
  }
  
  int ocfs2_super_lock(struct ocfs2_super *osb,
  		     int ex)
  {
  	int status = 0;
  	int level = ex ? LKM_EXMODE : LKM_PRMODE;
  	struct ocfs2_lock_res *lockres = &osb->osb_super_lockres;
  	struct buffer_head *bh;
  	struct ocfs2_slot_info *si = osb->slot_info;
  
  	mlog_entry_void();
  
  	if (ocfs2_is_hard_readonly(osb))
  		return -EROFS;
  
  	if (ocfs2_mount_local(osb))
  		goto bail;
  
  	status = ocfs2_cluster_lock(osb, lockres, level, 0, 0);
  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	/* The super block lock path is really in the best position to
  	 * know when resources covered by the lock need to be
  	 * refreshed, so we do it here. Of course, making sense of
  	 * everything is up to the caller :) */
  	status = ocfs2_should_refresh_lock_res(lockres);
  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  	if (status) {
  		bh = si->si_bh;
  		status = ocfs2_read_block(osb, bh->b_blocknr, &bh, 0,
  					  si->si_inode);
  		if (status == 0)
  			ocfs2_update_slot_info(si);
  
  		ocfs2_complete_lock_res_refresh(lockres, status);
  
  		if (status < 0)
  			mlog_errno(status);
  	}
  bail:
  	mlog_exit(status);
  	return status;
  }
  
  void ocfs2_super_unlock(struct ocfs2_super *osb,
  			int ex)
  {
  	int level = ex ? LKM_EXMODE : LKM_PRMODE;
  	struct ocfs2_lock_res *lockres = &osb->osb_super_lockres;
  
  	if (!ocfs2_mount_local(osb))
  		ocfs2_cluster_unlock(osb, lockres, level);
  }
  
  int ocfs2_rename_lock(struct ocfs2_super *osb)
  {
  	int status;
  	struct ocfs2_lock_res *lockres = &osb->osb_rename_lockres;
  
  	if (ocfs2_is_hard_readonly(osb))
  		return -EROFS;
  
  	if (ocfs2_mount_local(osb))
  		return 0;
  
  	status = ocfs2_cluster_lock(osb, lockres, LKM_EXMODE, 0, 0);
  	if (status < 0)
  		mlog_errno(status);
  
  	return status;
  }
  
  void ocfs2_rename_unlock(struct ocfs2_super *osb)
  {
  	struct ocfs2_lock_res *lockres = &osb->osb_rename_lockres;
  
  	if (!ocfs2_mount_local(osb))
  		ocfs2_cluster_unlock(osb, lockres, LKM_EXMODE);
  }
  
  int ocfs2_dentry_lock(struct dentry *dentry, int ex)
  {
  	int ret;
  	int level = ex ? LKM_EXMODE : LKM_PRMODE;
  	struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
  	struct ocfs2_super *osb = OCFS2_SB(dentry->d_sb);
  
  	BUG_ON(!dl);
  
  	if (ocfs2_is_hard_readonly(osb))
  		return -EROFS;
  
  	if (ocfs2_mount_local(osb))
  		return 0;
  
  	ret = ocfs2_cluster_lock(osb, &dl->dl_lockres, level, 0, 0);
  	if (ret < 0)
  		mlog_errno(ret);
  
  	return ret;
  }
  
  void ocfs2_dentry_unlock(struct dentry *dentry, int ex)
  {
  	int level = ex ? LKM_EXMODE : LKM_PRMODE;
  	struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
  	struct ocfs2_super *osb = OCFS2_SB(dentry->d_sb);
  
  	if (!ocfs2_mount_local(osb))
  		ocfs2_cluster_unlock(osb, &dl->dl_lockres, level);
  }
  
  /* Reference counting of the dlm debug structure. We want this because
   * open references on the debug inodes can live on after a mount, so
   * we can't rely on the ocfs2_super to always exist. */
  static void ocfs2_dlm_debug_free(struct kref *kref)
  {
  	struct ocfs2_dlm_debug *dlm_debug;
  
  	dlm_debug = container_of(kref, struct ocfs2_dlm_debug, d_refcnt);
  
  	kfree(dlm_debug);
  }
  
  void ocfs2_put_dlm_debug(struct ocfs2_dlm_debug *dlm_debug)
  {
  	if (dlm_debug)
  		kref_put(&dlm_debug->d_refcnt, ocfs2_dlm_debug_free);
  }
  
  static void ocfs2_get_dlm_debug(struct ocfs2_dlm_debug *debug)
  {
  	kref_get(&debug->d_refcnt);
  }
  
  struct ocfs2_dlm_debug *ocfs2_new_dlm_debug(void)
  {
  	struct ocfs2_dlm_debug *dlm_debug;
  
  	dlm_debug = kmalloc(sizeof(struct ocfs2_dlm_debug), GFP_KERNEL);
  	if (!dlm_debug) {
  		mlog_errno(-ENOMEM);
  		goto out;
  	}
  
  	kref_init(&dlm_debug->d_refcnt);
  	INIT_LIST_HEAD(&dlm_debug->d_lockres_tracking);
  	dlm_debug->d_locking_state = NULL;
  out:
  	return dlm_debug;
  }
  
  /* Access to this is arbitrated for us via seq_file->sem. */
  struct ocfs2_dlm_seq_priv {
  	struct ocfs2_dlm_debug *p_dlm_debug;
  	struct ocfs2_lock_res p_iter_res;
  	struct ocfs2_lock_res p_tmp_res;
  };
  
  static struct ocfs2_lock_res *ocfs2_dlm_next_res(struct ocfs2_lock_res *start,
  						 struct ocfs2_dlm_seq_priv *priv)
  {
  	struct ocfs2_lock_res *iter, *ret = NULL;
  	struct ocfs2_dlm_debug *dlm_debug = priv->p_dlm_debug;
  
  	assert_spin_locked(&ocfs2_dlm_tracking_lock);
  
  	list_for_each_entry(iter, &start->l_debug_list, l_debug_list) {
  		/* discover the head of the list */
  		if (&iter->l_debug_list == &dlm_debug->d_lockres_tracking) {
  			mlog(0, "End of list found, %p\n", ret);
  			break;
  		}
  
  		/* We track our "dummy" iteration lockres' by a NULL
  		 * l_ops field. */
  		if (iter->l_ops != NULL) {
  			ret = iter;
  			break;
  		}
  	}
  
  	return ret;
  }
  
  static void *ocfs2_dlm_seq_start(struct seq_file *m, loff_t *pos)
  {
  	struct ocfs2_dlm_seq_priv *priv = m->private;
  	struct ocfs2_lock_res *iter;
  
  	spin_lock(&ocfs2_dlm_tracking_lock);
  	iter = ocfs2_dlm_next_res(&priv->p_iter_res, priv);
  	if (iter) {
  		/* Since lockres' have the lifetime of their container
  		 * (which can be inodes, ocfs2_supers, etc) we want to
  		 * copy this out to a temporary lockres while still
  		 * under the spinlock. Obviously after this we can't
  		 * trust any pointers on the copy returned, but that's
  		 * ok as the information we want isn't typically held
  		 * in them. */
  		priv->p_tmp_res = *iter;
  		iter = &priv->p_tmp_res;
  	}
  	spin_unlock(&ocfs2_dlm_tracking_lock);
  
  	return iter;
  }
  
  static void ocfs2_dlm_seq_stop(struct seq_file *m, void *v)
  {
  }
  
  static void *ocfs2_dlm_seq_next(struct seq_file *m, void *v, loff_t *pos)
  {
  	struct ocfs2_dlm_seq_priv *priv = m->private;
  	struct ocfs2_lock_res *iter = v;
  	struct ocfs2_lock_res *dummy = &priv->p_iter_res;
  
  	spin_lock(&ocfs2_dlm_tracking_lock);
  	iter = ocfs2_dlm_next_res(iter, priv);
  	list_del_init(&dummy->l_debug_list);
  	if (iter) {
  		list_add(&dummy->l_debug_list, &iter->l_debug_list);
  		priv->p_tmp_res = *iter;
  		iter = &priv->p_tmp_res;
  	}
  	spin_unlock(&ocfs2_dlm_tracking_lock);
  
  	return iter;
  }
  
  /* So that debugfs.ocfs2 can determine which format is being used */
  #define OCFS2_DLM_DEBUG_STR_VERSION 1
  static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
  {
  	int i;
  	char *lvb;
  	struct ocfs2_lock_res *lockres = v;
  
  	if (!lockres)
  		return -EINVAL;
  
  	seq_printf(m, "0x%x\t", OCFS2_DLM_DEBUG_STR_VERSION);
  
  	if (lockres->l_type == OCFS2_LOCK_TYPE_DENTRY)
  		seq_printf(m, "%.*s%08x\t", OCFS2_DENTRY_LOCK_INO_START - 1,
  			   lockres->l_name,
  			   (unsigned int)ocfs2_get_dentry_lock_ino(lockres));
  	else
  		seq_printf(m, "%.*s\t", OCFS2_LOCK_ID_MAX_LEN, lockres->l_name);
  
  	seq_printf(m, "%d\t"
  		   "0x%lx\t"
  		   "0x%x\t"
  		   "0x%x\t"
  		   "%u\t"
  		   "%u\t"
  		   "%d\t"
  		   "%d\t",
  		   lockres->l_level,
  		   lockres->l_flags,
  		   lockres->l_action,
  		   lockres->l_unlock_action,
  		   lockres->l_ro_holders,
  		   lockres->l_ex_holders,
  		   lockres->l_requested,
  		   lockres->l_blocking);
  
  	/* Dump the raw LVB */
  	lvb = lockres->l_lksb.lvb;
  	for(i = 0; i < DLM_LVB_LEN; i++)
  		seq_printf(m, "0x%x\t", lvb[i]);
  
  	/* End the line */
  	seq_printf(m, "\n");
  	return 0;
  }
  
  static struct seq_operations ocfs2_dlm_seq_ops = {
  	.start =	ocfs2_dlm_seq_start,
  	.stop =		ocfs2_dlm_seq_stop,
  	.next =		ocfs2_dlm_seq_next,
  	.show =		ocfs2_dlm_seq_show,
  };
  
  static int ocfs2_dlm_debug_release(struct inode *inode, struct file *file)
  {
  	struct seq_file *seq = (struct seq_file *) file->private_data;
  	struct ocfs2_dlm_seq_priv *priv = seq->private;
  	struct ocfs2_lock_res *res = &priv->p_iter_res;
  
  	ocfs2_remove_lockres_tracking(res);
  	ocfs2_put_dlm_debug(priv->p_dlm_debug);
  	return seq_release_private(inode, file);
  }
  
  static int ocfs2_dlm_debug_open(struct inode *inode, struct file *file)
  {
  	int ret;
  	struct ocfs2_dlm_seq_priv *priv;
  	struct seq_file *seq;
  	struct ocfs2_super *osb;
  
  	priv = kzalloc(sizeof(struct ocfs2_dlm_seq_priv), GFP_KERNEL);
  	if (!priv) {
  		ret = -ENOMEM;
  		mlog_errno(ret);
  		goto out;
  	}
  	osb = inode->i_private;
  	ocfs2_get_dlm_debug(osb->osb_dlm_debug);
  	priv->p_dlm_debug = osb->osb_dlm_debug;
  	INIT_LIST_HEAD(&priv->p_iter_res.l_debug_list);
  
  	ret = seq_open(file, &ocfs2_dlm_seq_ops);
  	if (ret) {
  		kfree(priv);
  		mlog_errno(ret);
  		goto out;
  	}
  
  	seq = (struct seq_file *) file->private_data;
  	seq->private = priv;
  
  	ocfs2_add_lockres_tracking(&priv->p_iter_res,
  				   priv->p_dlm_debug);
  
  out:
  	return ret;
  }
  
  static const struct file_operations ocfs2_dlm_debug_fops = {
  	.open =		ocfs2_dlm_debug_open,
  	.release =	ocfs2_dlm_debug_release,
  	.read =		seq_read,
  	.llseek =	seq_lseek,
  };
  
  static int ocfs2_dlm_init_debug(struct ocfs2_super *osb)
  {
  	int ret = 0;
  	struct ocfs2_dlm_debug *dlm_debug = osb->osb_dlm_debug;
  
  	dlm_debug->d_locking_state = debugfs_create_file("locking_state",
  							 S_IFREG|S_IRUSR,
  							 osb->osb_debug_root,
  							 osb,
  							 &ocfs2_dlm_debug_fops);
  	if (!dlm_debug->d_locking_state) {
  		ret = -EINVAL;
  		mlog(ML_ERROR,
  		     "Unable to create locking state debugfs file.\n");
  		goto out;
  	}
  
  	ocfs2_get_dlm_debug(dlm_debug);
  out:
  	return ret;
  }
  
  static void ocfs2_dlm_shutdown_debug(struct ocfs2_super *osb)
  {
  	struct ocfs2_dlm_debug *dlm_debug = osb->osb_dlm_debug;
  
  	if (dlm_debug) {
  		debugfs_remove(dlm_debug->d_locking_state);
  		ocfs2_put_dlm_debug(dlm_debug);
  	}
  }
  
  int ocfs2_dlm_init(struct ocfs2_super *osb)
  {
  	int status = 0;
  	u32 dlm_key;
  	struct dlm_ctxt *dlm = NULL;
  
  	mlog_entry_void();
  
  	if (ocfs2_mount_local(osb))
  		goto local;
  
  	status = ocfs2_dlm_init_debug(osb);
  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	/* launch vote thread */
  	osb->vote_task = kthread_run(ocfs2_vote_thread, osb, "ocfs2vote");
  	if (IS_ERR(osb->vote_task)) {
  		status = PTR_ERR(osb->vote_task);
  		osb->vote_task = NULL;
  		mlog_errno(status);
  		goto bail;
  	}
  
  	/* used by the dlm code to make message headers unique, each
  	 * node in this domain must agree on this. */
  	dlm_key = crc32_le(0, osb->uuid_str, strlen(osb->uuid_str));
  
  	/* for now, uuid == domain */
  	dlm = dlm_register_domain(osb->uuid_str, dlm_key);
  	if (IS_ERR(dlm)) {
  		status = PTR_ERR(dlm);
  		mlog_errno(status);
  		goto bail;
  	}
  
  	dlm_register_eviction_cb(dlm, &osb->osb_eviction_cb);
  
  local:
  	ocfs2_super_lock_res_init(&osb->osb_super_lockres, osb);
  	ocfs2_rename_lock_res_init(&osb->osb_rename_lockres, osb);
  
  	osb->dlm = dlm;
  
  	status = 0;
  bail:
  	if (status < 0) {
  		ocfs2_dlm_shutdown_debug(osb);
  		if (osb->vote_task)
  			kthread_stop(osb->vote_task);
  	}
  
  	mlog_exit(status);
  	return status;
  }
  
  void ocfs2_dlm_shutdown(struct ocfs2_super *osb)
  {
  	mlog_entry_void();
  
  	dlm_unregister_eviction_cb(&osb->osb_eviction_cb);
  
  	ocfs2_drop_osb_locks(osb);
  
  	if (osb->vote_task) {
  		kthread_stop(osb->vote_task);
  		osb->vote_task = NULL;
  	}
  
  	ocfs2_lock_res_free(&osb->osb_super_lockres);
  	ocfs2_lock_res_free(&osb->osb_rename_lockres);
  
  	dlm_unregister_domain(osb->dlm);
  	osb->dlm = NULL;
  
  	ocfs2_dlm_shutdown_debug(osb);
  
  	mlog_exit_void();
  }
  
  static void ocfs2_unlock_ast(void *opaque, enum dlm_status status)
  {
  	struct ocfs2_lock_res *lockres = opaque;
  	unsigned long flags;
  
  	mlog_entry_void();
  
  	mlog(0, "UNLOCK AST called on lock %s, action = %d\n", lockres->l_name,
  	     lockres->l_unlock_action);
  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	/* We tried to cancel a convert request, but it was already
  	 * granted. All we want to do here is clear our unlock
  	 * state. The wake_up call done at the bottom is redundant
  	 * (ocfs2_prepare_cancel_convert doesn't sleep on this) but doesn't
  	 * hurt anything anyway */
  	if (status == DLM_CANCELGRANT &&
  	    lockres->l_unlock_action == OCFS2_UNLOCK_CANCEL_CONVERT) {
  		mlog(0, "Got cancelgrant for %s\n", lockres->l_name);
  
  		/* We don't clear the busy flag in this case as it
  		 * should have been cleared by the ast which the dlm
  		 * has called. */
  		goto complete_unlock;
  	}
  
  	if (status != DLM_NORMAL) {
  		mlog(ML_ERROR, "Dlm passes status %d for lock %s, "
  		     "unlock_action %d\n", status, 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\n", lockres->l_name);
  		lockres->l_action = OCFS2_AST_INVALID;
  		break;
  	case OCFS2_UNLOCK_DROP_LOCK:
  		lockres->l_level = LKM_IVMODE;
  		break;
  	default:
  		BUG();
  	}
  
  	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
  complete_unlock:
  	lockres->l_unlock_action = OCFS2_UNLOCK_INVALID;
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  	wake_up(&lockres->l_event);
  
  	mlog_exit_void();
  }
  
  static int ocfs2_drop_lock(struct ocfs2_super *osb,
  			   struct ocfs2_lock_res *lockres)
  {
  	enum dlm_status status;
  	unsigned long flags;
  	int lkm_flags = 0;
  
  	/* We didn't get anywhere near actually using this lockres. */
  	if (!(lockres->l_flags & OCFS2_LOCK_INITIALIZED))
  		goto out;
  
  	if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB)
  		lkm_flags |= LKM_VALBLK;
  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  
  	mlog_bug_on_msg(!(lockres->l_flags & OCFS2_LOCK_FREEING),
  			"lockres %s, flags 0x%lx\n",
  			lockres->l_name, lockres->l_flags);
  
  	while (lockres->l_flags & OCFS2_LOCK_BUSY) {
  		mlog(0, "waiting on busy lock \"%s\": flags = %lx, action = "
  		     "%u, unlock_action = %u\n",
  		     lockres->l_name, lockres->l_flags, lockres->l_action,
  		     lockres->l_unlock_action);
  
  		spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  		/* XXX: Today we just wait on any busy
  		 * locks... Perhaps we need to cancel converts in the
  		 * future? */
  		ocfs2_wait_on_busy_lock(lockres);
  
  		spin_lock_irqsave(&lockres->l_lock, flags);
  	}
  
  	if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB) {
  		if (lockres->l_flags & OCFS2_LOCK_ATTACHED &&
  		    lockres->l_level == LKM_EXMODE &&
  		    !(lockres->l_flags & OCFS2_LOCK_NEEDS_REFRESH))
  			lockres->l_ops->set_lvb(lockres);
  	}
  
  	if (lockres->l_flags & OCFS2_LOCK_BUSY)
  		mlog(ML_ERROR, "destroying busy lock: \"%s\"\n",
  		     lockres->l_name);
  	if (lockres->l_flags & OCFS2_LOCK_BLOCKED)
  		mlog(0, "destroying blocked lock: \"%s\"\n", lockres->l_name);
  
  	if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED)) {
  		spin_unlock_irqrestore(&lockres->l_lock, flags);
  		goto out;
  	}
  
  	lockres_clear_flags(lockres, OCFS2_LOCK_ATTACHED);
  
  	/* make sure we never get here while waiting for an ast to
  	 * fire. */
  	BUG_ON(lockres->l_action != OCFS2_AST_INVALID);
  
  	/* is this necessary? */
  	lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
  	lockres->l_unlock_action = OCFS2_UNLOCK_DROP_LOCK;
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  	mlog(0, "lock %s\n", lockres->l_name);
  
  	status = dlmunlock(osb->dlm, &lockres->l_lksb, lkm_flags,
  			   ocfs2_unlock_ast, lockres);
  	if (status != DLM_NORMAL) {
  		ocfs2_log_dlm_error("dlmunlock", status, lockres);
  		mlog(ML_ERROR, "lockres flags: %lu\n", lockres->l_flags);
  		dlm_print_one_lock(lockres->l_lksb.lockid);
  		BUG();
  	}
  	mlog(0, "lock %s, successfull return from dlmunlock\n",
  	     lockres->l_name);
  
  	ocfs2_wait_on_busy_lock(lockres);
  out:
  	mlog_exit(0);
  	return 0;
  }
  
  /* Mark the lockres as being dropped. It will no longer be
   * queued if blocking, but we still may have to wait on it
   * being dequeued from the vote thread before we can consider
   * it safe to drop. 
   *
   * You can *not* attempt to call cluster_lock on this lockres anymore. */
  void ocfs2_mark_lockres_freeing(struct ocfs2_lock_res *lockres)
  {
  	int status;
  	struct ocfs2_mask_waiter mw;
  	unsigned long flags;
  
  	ocfs2_init_mask_waiter(&mw);
  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	lockres->l_flags |= OCFS2_LOCK_FREEING;
  	while (lockres->l_flags & OCFS2_LOCK_QUEUED) {
  		lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_QUEUED, 0);
  		spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  		mlog(0, "Waiting on lockres %s\n", lockres->l_name);
  
  		status = ocfs2_wait_for_mask(&mw);
  		if (status)
  			mlog_errno(status);
  
  		spin_lock_irqsave(&lockres->l_lock, flags);
  	}
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  }
  
  void ocfs2_simple_drop_lockres(struct ocfs2_super *osb,
  			       struct ocfs2_lock_res *lockres)
  {
  	int ret;
  
  	ocfs2_mark_lockres_freeing(lockres);
  	ret = ocfs2_drop_lock(osb, lockres);
  	if (ret)
  		mlog_errno(ret);
  }
  
  static void ocfs2_drop_osb_locks(struct ocfs2_super *osb)
  {
  	ocfs2_simple_drop_lockres(osb, &osb->osb_super_lockres);
  	ocfs2_simple_drop_lockres(osb, &osb->osb_rename_lockres);
  }
  
  int ocfs2_drop_inode_locks(struct inode *inode)
  {
  	int status, err;
  
  	mlog_entry_void();
  
  	/* No need to call ocfs2_mark_lockres_freeing here -
  	 * ocfs2_clear_inode has done it for us. */
  
  	err = ocfs2_drop_lock(OCFS2_SB(inode->i_sb),
  			      &OCFS2_I(inode)->ip_open_lockres);
  	if (err < 0)
  		mlog_errno(err);
  
  	status = err;
  
  	err = ocfs2_drop_lock(OCFS2_SB(inode->i_sb),
  			      &OCFS2_I(inode)->ip_data_lockres);
  	if (err < 0)
  		mlog_errno(err);
  	if (err < 0 && !status)
  		status = err;
  
  	err = ocfs2_drop_lock(OCFS2_SB(inode->i_sb),
  			      &OCFS2_I(inode)->ip_meta_lockres);
  	if (err < 0)
  		mlog_errno(err);
  	if (err < 0 && !status)
  		status = err;
  
  	err = ocfs2_drop_lock(OCFS2_SB(inode->i_sb),
  			      &OCFS2_I(inode)->ip_rw_lockres);
  	if (err < 0)
  		mlog_errno(err);
  	if (err < 0 && !status)
  		status = err;
  
  	mlog_exit(status);
  	return status;
  }
  
  static void ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
  				      int new_level)
  {
  	assert_spin_locked(&lockres->l_lock);
  
  	BUG_ON(lockres->l_blocking <= LKM_NLMODE);
  
  	if (lockres->l_level <= new_level) {
  		mlog(ML_ERROR, "lockres->l_level (%u) <= new_level (%u)\n",
  		     lockres->l_level, new_level);
  		BUG();
  	}
  
  	mlog(0, "lock %s, new_level = %d, l_blocking = %d\n",
  	     lockres->l_name, new_level, lockres->l_blocking);
  
  	lockres->l_action = OCFS2_AST_DOWNCONVERT;
  	lockres->l_requested = new_level;
  	lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
  }
  
  static int ocfs2_downconvert_lock(struct ocfs2_super *osb,
  				  struct ocfs2_lock_res *lockres,
  				  int new_level,
  				  int lvb)
  {
  	int ret, dlm_flags = LKM_CONVERT;
  	enum dlm_status status;
  
  	mlog_entry_void();
  
  	if (lvb)
  		dlm_flags |= LKM_VALBLK;
  
  	status = dlmlock(osb->dlm,
  			 new_level,
  			 &lockres->l_lksb,
  			 dlm_flags,
  			 lockres->l_name,
  			 OCFS2_LOCK_ID_MAX_LEN - 1,
  			 ocfs2_locking_ast,
  			 lockres,
  			 ocfs2_blocking_ast);
  	if (status != DLM_NORMAL) {
  		ocfs2_log_dlm_error("dlmlock", status, lockres);
  		ret = -EINVAL;
  		ocfs2_recover_from_dlm_error(lockres, 1);
  		goto bail;
  	}
  
  	ret = 0;
  bail:
  	mlog_exit(ret);
  	return ret;
  }
  
  /* returns 1 when the caller should unlock and call dlmunlock */
  static int ocfs2_prepare_cancel_convert(struct ocfs2_super *osb,
  				        struct ocfs2_lock_res *lockres)
  {
  	assert_spin_locked(&lockres->l_lock);
  
  	mlog_entry_void();
  	mlog(0, "lock %s\n", lockres->l_name);
  
  	if (lockres->l_unlock_action == OCFS2_UNLOCK_CANCEL_CONVERT) {
  		/* If we're already trying to cancel a lock conversion
  		 * then just drop the spinlock and allow the caller to
  		 * requeue this lock. */
  
  		mlog(0, "Lockres %s, skip convert\n", lockres->l_name);
  		return 0;
  	}
  
  	/* were we in a convert when we got the bast fire? */
  	BUG_ON(lockres->l_action != OCFS2_AST_CONVERT &&
  	       lockres->l_action != OCFS2_AST_DOWNCONVERT);
  	/* set things up for the unlockast to know to just
  	 * clear out the ast_action and unset busy, etc. */
  	lockres->l_unlock_action = OCFS2_UNLOCK_CANCEL_CONVERT;
  
  	mlog_bug_on_msg(!(lockres->l_flags & OCFS2_LOCK_BUSY),
  			"lock %s, invalid flags: 0x%lx\n",
  			lockres->l_name, lockres->l_flags);
  
  	return 1;
  }
  
  static int ocfs2_cancel_convert(struct ocfs2_super *osb,
  				struct ocfs2_lock_res *lockres)
  {
  	int ret;
  	enum dlm_status status;
  
  	mlog_entry_void();
  	mlog(0, "lock %s\n", lockres->l_name);
  
  	ret = 0;
  	status = dlmunlock(osb->dlm,
  			   &lockres->l_lksb,
  			   LKM_CANCEL,
  			   ocfs2_unlock_ast,
  			   lockres);
  	if (status != DLM_NORMAL) {
  		ocfs2_log_dlm_error("dlmunlock", status, lockres);
  		ret = -EINVAL;
  		ocfs2_recover_from_dlm_error(lockres, 0);
  	}
  
  	mlog(0, "lock %s return from dlmunlock\n", lockres->l_name);
  
  	mlog_exit(ret);
  	return ret;
  }
  
  static int ocfs2_unblock_lock(struct ocfs2_super *osb,
  			      struct ocfs2_lock_res *lockres,
  			      struct ocfs2_unblock_ctl *ctl)
  {
  	unsigned long flags;
  	int blocking;
  	int new_level;
  	int ret = 0;
  	int set_lvb = 0;
  
  	mlog_entry_void();
  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  
  	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BLOCKED));
  
  recheck:
  	if (lockres->l_flags & OCFS2_LOCK_BUSY) {
  		ctl->requeue = 1;
  		ret = ocfs2_prepare_cancel_convert(osb, lockres);
  		spin_unlock_irqrestore(&lockres->l_lock, flags);
  		if (ret) {
  			ret = ocfs2_cancel_convert(osb, lockres);
  			if (ret < 0)
  				mlog_errno(ret);
  		}
  		goto leave;
  	}
  
  	/* if we're blocking an exclusive and we have *any* holders,
  	 * then requeue. */
  	if ((lockres->l_blocking == LKM_EXMODE)
  	    && (lockres->l_ex_holders || lockres->l_ro_holders))
  		goto leave_requeue;
  
  	/* If it's a PR we're blocking, then only
  	 * requeue if we've got any EX holders */
  	if (lockres->l_blocking == LKM_PRMODE &&
  	    lockres->l_ex_holders)
  		goto leave_requeue;
  
  	/*
  	 * Can we get a lock in this state if the holder counts are
  	 * zero? The meta data unblock code used to check this.
  	 */
  	if ((lockres->l_ops->flags & LOCK_TYPE_REQUIRES_REFRESH)
  	    && (lockres->l_flags & OCFS2_LOCK_REFRESHING))
  		goto leave_requeue;
  
  	new_level = ocfs2_highest_compat_lock_level(lockres->l_blocking);
  
  	if (lockres->l_ops->check_downconvert
  	    && !lockres->l_ops->check_downconvert(lockres, new_level))
  		goto leave_requeue;
  
  	/* If we get here, then we know that there are no more
  	 * incompatible holders (and anyone asking for an incompatible
  	 * lock is blocked). We can now downconvert the lock */
  	if (!lockres->l_ops->downconvert_worker)
  		goto downconvert;
  
  	/* Some lockres types want to do a bit of work before
  	 * downconverting a lock. Allow that here. The worker function
  	 * may sleep, so we save off a copy of what we're blocking as
  	 * it may change while we're not holding the spin lock. */
  	blocking = lockres->l_blocking;
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  	ctl->unblock_action = lockres->l_ops->downconvert_worker(lockres, blocking);
  
  	if (ctl->unblock_action == UNBLOCK_STOP_POST)
  		goto leave;
  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	if (blocking != lockres->l_blocking) {
  		/* If this changed underneath us, then we can't drop
  		 * it just yet. */
  		goto recheck;
  	}
  
  downconvert:
  	ctl->requeue = 0;
  
  	if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB) {
  		if (lockres->l_level == LKM_EXMODE)
  			set_lvb = 1;
  
  		/*
  		 * We only set the lvb if the lock has been fully
  		 * refreshed - otherwise we risk setting stale
  		 * data. Otherwise, there's no need to actually clear
  		 * out the lvb here as it's value is still valid.
  		 */
  		if (set_lvb && !(lockres->l_flags & OCFS2_LOCK_NEEDS_REFRESH))
  			lockres->l_ops->set_lvb(lockres);
  	}
  
  	ocfs2_prepare_downconvert(lockres, new_level);
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  	ret = ocfs2_downconvert_lock(osb, lockres, new_level, set_lvb);
  leave:
  	mlog_exit(ret);
  	return ret;
  
  leave_requeue:
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  	ctl->requeue = 1;
  
  	mlog_exit(0);
  	return 0;
  }
  
  static int ocfs2_data_convert_worker(struct ocfs2_lock_res *lockres,
  				     int blocking)
  {
  	struct inode *inode;
  	struct address_space *mapping;
  
         	inode = ocfs2_lock_res_inode(lockres);
  	mapping = inode->i_mapping;
  
  	/*
  	 * We need this before the filemap_fdatawrite() so that it can
  	 * transfer the dirty bit from the PTE to the
  	 * page. Unfortunately this means that even for EX->PR
  	 * downconverts, we'll lose our mappings and have to build
  	 * them up again.
  	 */
  	unmap_mapping_range(mapping, 0, 0, 0);
  
  	if (filemap_fdatawrite(mapping)) {
  		mlog(ML_ERROR, "Could not sync inode %llu for downconvert!",
  		     (unsigned long long)OCFS2_I(inode)->ip_blkno);
  	}
  	sync_mapping_buffers(mapping);
  	if (blocking == LKM_EXMODE) {
  		truncate_inode_pages(mapping, 0);
  	} else {
  		/* We only need to wait on the I/O if we're not also
  		 * truncating pages because truncate_inode_pages waits
  		 * for us above. We don't truncate pages if we're
  		 * blocking anything < EXMODE because we want to keep
  		 * them around in that case. */
  		filemap_fdatawait(mapping);
  	}
  
  	return UNBLOCK_CONTINUE;
  }
  
  static int ocfs2_check_meta_downconvert(struct ocfs2_lock_res *lockres,
  					int new_level)
  {
  	struct inode *inode = ocfs2_lock_res_inode(lockres);
  	int checkpointed = ocfs2_inode_fully_checkpointed(inode);
  
  	BUG_ON(new_level != LKM_NLMODE && new_level != LKM_PRMODE);
  	BUG_ON(lockres->l_level != LKM_EXMODE && !checkpointed);
  
  	if (checkpointed)
  		return 1;
  
  	ocfs2_start_checkpoint(OCFS2_SB(inode->i_sb));
  	return 0;
  }
  
  static void ocfs2_set_meta_lvb(struct ocfs2_lock_res *lockres)
  {
  	struct inode *inode = ocfs2_lock_res_inode(lockres);
  
  	__ocfs2_stuff_meta_lvb(inode);
  }
  
  /*
   * Does the final reference drop on our dentry lock. Right now this
   * happens in the vote thread, but we could choose to simplify the
   * dlmglue API and push these off to the ocfs2_wq in the future.
   */
  static void ocfs2_dentry_post_unlock(struct ocfs2_super *osb,
  				     struct ocfs2_lock_res *lockres)
  {
  	struct ocfs2_dentry_lock *dl = ocfs2_lock_res_dl(lockres);
  	ocfs2_dentry_lock_put(osb, dl);
  }
  
  /*
   * d_delete() matching dentries before the lock downconvert.
   *
   * At this point, any process waiting to destroy the
   * dentry_lock due to last ref count is stopped by the
   * OCFS2_LOCK_QUEUED flag.
   *
   * We have two potential problems
   *
   * 1) If we do the last reference drop on our dentry_lock (via dput)
   *    we'll wind up in ocfs2_release_dentry_lock(), waiting on
   *    the downconvert to finish. Instead we take an elevated
   *    reference and push the drop until after we've completed our
   *    unblock processing.
   *
   * 2) There might be another process with a final reference,
   *    waiting on us to finish processing. If this is the case, we
   *    detect it and exit out - there's no more dentries anyway.
   */
  static int ocfs2_dentry_convert_worker(struct ocfs2_lock_res *lockres,
  				       int blocking)
  {
  	struct ocfs2_dentry_lock *dl = ocfs2_lock_res_dl(lockres);
  	struct ocfs2_inode_info *oi = OCFS2_I(dl->dl_inode);
  	struct dentry *dentry;
  	unsigned long flags;
  	int extra_ref = 0;
  
  	/*
  	 * This node is blocking another node from getting a read
  	 * lock. This happens when we've renamed within a
  	 * directory. We've forced the other nodes to d_delete(), but
  	 * we never actually dropped our lock because it's still
  	 * valid. The downconvert code will retain a PR for this node,
  	 * so there's no further work to do.
  	 */
  	if (blocking == LKM_PRMODE)
  		return UNBLOCK_CONTINUE;
  
  	/*
  	 * Mark this inode as potentially orphaned. The code in
  	 * ocfs2_delete_inode() will figure out whether it actually
  	 * needs to be freed or not.
  	 */
  	spin_lock(&oi->ip_lock);
  	oi->ip_flags |= OCFS2_INODE_MAYBE_ORPHANED;
  	spin_unlock(&oi->ip_lock);
  
  	/*
  	 * Yuck. We need to make sure however that the check of
  	 * OCFS2_LOCK_FREEING and the extra reference are atomic with
  	 * respect to a reference decrement or the setting of that
  	 * flag.
  	 */
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	spin_lock(&dentry_attach_lock);
  	if (!(lockres->l_flags & OCFS2_LOCK_FREEING)
  	    && dl->dl_count) {
  		dl->dl_count++;
  		extra_ref = 1;
  	}
  	spin_unlock(&dentry_attach_lock);
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  	mlog(0, "extra_ref = %d\n", extra_ref);
  
  	/*
  	 * We have a process waiting on us in ocfs2_dentry_iput(),
  	 * which means we can't have any more outstanding
  	 * aliases. There's no need to do any more work.
  	 */
  	if (!extra_ref)
  		return UNBLOCK_CONTINUE;
  
  	spin_lock(&dentry_attach_lock);
  	while (1) {
  		dentry = ocfs2_find_local_alias(dl->dl_inode,
  						dl->dl_parent_blkno, 1);
  		if (!dentry)
  			break;
  		spin_unlock(&dentry_attach_lock);
  
  		mlog(0, "d_delete(%.*s);\n", dentry->d_name.len,
  		     dentry->d_name.name);
  
  		/*
  		 * The following dcache calls may do an
  		 * iput(). Normally we don't want that from the
  		 * downconverting thread, but in this case it's ok
  		 * because the requesting node already has an
  		 * exclusive lock on the inode, so it can't be queued
  		 * for a downconvert.
  		 */
  		d_delete(dentry);
  		dput(dentry);
  
  		spin_lock(&dentry_attach_lock);
  	}
  	spin_unlock(&dentry_attach_lock);
  
  	/*
  	 * If we are the last holder of this dentry lock, there is no
  	 * reason to downconvert so skip straight to the unlock.
  	 */
  	if (dl->dl_count == 1)
  		return UNBLOCK_STOP_POST;
  
  	return UNBLOCK_CONTINUE_POST;
  }
  
  void ocfs2_process_blocked_lock(struct ocfs2_super *osb,
  				struct ocfs2_lock_res *lockres)
  {
  	int status;
  	struct ocfs2_unblock_ctl ctl = {0, 0,};
  	unsigned long flags;
  
  	/* Our reference to the lockres in this function can be
  	 * considered valid until we remove the OCFS2_LOCK_QUEUED
  	 * flag. */
  
  	mlog_entry_void();
  
  	BUG_ON(!lockres);
  	BUG_ON(!lockres->l_ops);
  
  	mlog(0, "lockres %s blocked.\n", lockres->l_name);
  
  	/* Detect whether a lock has been marked as going away while
  	 * the vote thread was processing other things. A lock can
  	 * still be marked with OCFS2_LOCK_FREEING after this check,
  	 * but short circuiting here will still save us some
  	 * performance. */
  	spin_lock_irqsave(&lockres->l_lock, flags);
  	if (lockres->l_flags & OCFS2_LOCK_FREEING)
  		goto unqueue;
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  	status = ocfs2_unblock_lock(osb, lockres, &ctl);
  	if (status < 0)
  		mlog_errno(status);
  
  	spin_lock_irqsave(&lockres->l_lock, flags);
  unqueue:
  	if (lockres->l_flags & OCFS2_LOCK_FREEING || !ctl.requeue) {
  		lockres_clear_flags(lockres, OCFS2_LOCK_QUEUED);
  	} else
  		ocfs2_schedule_blocked_lock(osb, lockres);
  
  	mlog(0, "lockres %s, requeue = %s.\n", lockres->l_name,
  	     ctl.requeue ? "yes" : "no");
  	spin_unlock_irqrestore(&lockres->l_lock, flags);
  
  	if (ctl.unblock_action != UNBLOCK_CONTINUE
  	    && lockres->l_ops->post_unlock)
  		lockres->l_ops->post_unlock(osb, lockres);
  
  	mlog_exit_void();
  }
  
  static void ocfs2_schedule_blocked_lock(struct ocfs2_super *osb,
  					struct ocfs2_lock_res *lockres)
  {
  	mlog_entry_void();
  
  	assert_spin_locked(&lockres->l_lock);
  
  	if (lockres->l_flags & OCFS2_LOCK_FREEING) {
  		/* Do not schedule a lock for downconvert when it's on
  		 * the way to destruction - any nodes wanting access
  		 * to the resource will get it soon. */
  		mlog(0, "Lockres %s won't be scheduled: flags 0x%lx\n",
  		     lockres->l_name, lockres->l_flags);
  		return;
  	}
  
  	lockres_or_flags(lockres, OCFS2_LOCK_QUEUED);
  
  	spin_lock(&osb->vote_task_lock);
  	if (list_empty(&lockres->l_blocked_list)) {
  		list_add_tail(&lockres->l_blocked_list,
  			      &osb->blocked_lock_list);
  		osb->blocked_lock_count++;
  	}
  	spin_unlock(&osb->vote_task_lock);
  
  	mlog_exit_void();
  }
  