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dlmglue.c

/* -*- 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/smp_lock.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 "dlmglue.h"
#include "extent_map.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 void ocfs2_inode_ast_func(void *opaque);
static void ocfs2_inode_bast_func(void *opaque,
                          int level);
static void ocfs2_super_ast_func(void *opaque);
static void ocfs2_super_bast_func(void *opaque,
                          int level);
static void ocfs2_rename_ast_func(void *opaque);
static void ocfs2_rename_bast_func(void *opaque,
                           int level);

/* so far, all locks have gotten along with the same unlock ast */
static void ocfs2_unlock_ast_func(void *opaque,
                          enum dlm_status status);
static int ocfs2_do_unblock_meta(struct inode *inode,
                         int *requeue);
static int ocfs2_unblock_meta(struct ocfs2_lock_res *lockres,
                        int *requeue);
static int ocfs2_unblock_data(struct ocfs2_lock_res *lockres,
                        int *requeue);
static int ocfs2_unblock_inode_lock(struct ocfs2_lock_res *lockres,
                        int *requeue);
static int ocfs2_unblock_osb_lock(struct ocfs2_lock_res *lockres,
                          int *requeue);
typedef void (ocfs2_convert_worker_t)(struct ocfs2_lock_res *, int);
static int ocfs2_generic_unblock_lock(struct ocfs2_super *osb,
                              struct ocfs2_lock_res *lockres,
                              int *requeue,
                              ocfs2_convert_worker_t *worker);

struct ocfs2_lock_res_ops {
      void (*ast)(void *);
      void (*bast)(void *, int);
      void (*unlock_ast)(void *, enum dlm_status);
      int  (*unblock)(struct ocfs2_lock_res *, int *);
};

static struct ocfs2_lock_res_ops ocfs2_inode_rw_lops = {
      .ast        = ocfs2_inode_ast_func,
      .bast       = ocfs2_inode_bast_func,
      .unlock_ast = ocfs2_unlock_ast_func,
      .unblock    = ocfs2_unblock_inode_lock,
};

static struct ocfs2_lock_res_ops ocfs2_inode_meta_lops = {
      .ast        = ocfs2_inode_ast_func,
      .bast       = ocfs2_inode_bast_func,
      .unlock_ast = ocfs2_unlock_ast_func,
      .unblock    = ocfs2_unblock_meta,
};

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

static struct ocfs2_lock_res_ops ocfs2_inode_data_lops = {
      .ast        = ocfs2_inode_ast_func,
      .bast       = ocfs2_inode_bast_func,
      .unlock_ast = ocfs2_unlock_ast_func,
      .unblock    = ocfs2_unblock_data,
};

static struct ocfs2_lock_res_ops ocfs2_super_lops = {
      .ast        = ocfs2_super_ast_func,
      .bast       = ocfs2_super_bast_func,
      .unlock_ast = ocfs2_unlock_ast_func,
      .unblock    = ocfs2_unblock_osb_lock,
};

static struct ocfs2_lock_res_ops ocfs2_rename_lops = {
      .ast        = ocfs2_rename_ast_func,
      .bast       = ocfs2_rename_bast_func,
      .unlock_ast = ocfs2_unlock_ast_func,
      .unblock    = ocfs2_unblock_osb_lock,
};

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;
}

static inline int ocfs2_is_super_lock(struct ocfs2_lock_res *lockres)
{
      return lockres->l_type == OCFS2_LOCK_TYPE_SUPER;
}

static inline int ocfs2_is_rename_lock(struct ocfs2_lock_res *lockres)
{
      return lockres->l_type == OCFS2_LOCK_TYPE_RENAME;
}

static inline struct ocfs2_super *ocfs2_lock_res_super(struct ocfs2_lock_res *lockres)
{
      BUG_ON(!ocfs2_is_super_lock(lockres)
             && !ocfs2_is_rename_lock(lockres));

      return (struct ocfs2_super *) lockres->l_priv;
}

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 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 inline int ocfs2_can_downconvert_meta_lock(struct inode *inode,
                                      struct ocfs2_lock_res *lockres,
                                      int new_level);

static char *ocfs2_lock_type_strings[] = {
      [OCFS2_LOCK_TYPE_META] = "Meta",
      [OCFS2_LOCK_TYPE_DATA] = "Data",
      [OCFS2_LOCK_TYPE_SUPER] = "Super",
      [OCFS2_LOCK_TYPE_RENAME] = "Rename",
      /* Need to differntiate from [R]ename.. serializing writes is the
       * important job it does, anyway. */
      [OCFS2_LOCK_TYPE_RW] = "Write/Read",
};

static char *ocfs2_lock_type_string(enum ocfs2_lock_type type)
{
      mlog_bug_on_msg(type >= OCFS2_NUM_LOCK_TYPES, "%d\n", type);
      return ocfs2_lock_type_strings[type];
}

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,
                               u64 blkno,
                               u32 generation,
                               struct ocfs2_lock_res_ops *ops,
                               void *priv)
{
      ocfs2_build_lock_name(type, blkno, generation, res->l_name);

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

      ocfs2_lock_res_init_common(OCFS2_SB(inode->i_sb), res, type,
                           OCFS2_I(inode)->ip_blkno,
                           inode->i_generation, ops, inode);
}

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_lock_res_init_common(osb, res, OCFS2_LOCK_TYPE_SUPER,
                           OCFS2_SUPER_BLOCK_BLKNO, 0,
                           &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_lock_res_init_common(osb, res, OCFS2_LOCK_TYPE_RENAME, 0, 0,
                           &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_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_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 void ocfs2_inode_ast_func(void *opaque)
{
      struct ocfs2_lock_res *lockres = opaque;
      struct inode *inode;
      struct dlm_lockstatus *lksb;
      unsigned long flags;

      mlog_entry_void();

      inode = ocfs2_lock_res_inode(lockres);

      mlog(0, "AST fired for inode %llu, l_action = %u, type = %s\n",
           (unsigned long long)OCFS2_I(inode)->ip_blkno, lockres->l_action,
           ocfs2_lock_type_string(lockres->l_type));

      BUG_ON(!ocfs2_is_inode_lock(lockres));

      spin_lock_irqsave(&lockres->l_lock, flags);

      lksb = &(lockres->l_lksb);
      if (lksb->status != DLM_NORMAL) {
            mlog(ML_ERROR, "ocfs2_inode_ast_func: lksb status value of %u "
                 "on inode %llu\n", lksb->status,
                 (unsigned long long)OCFS2_I(inode)->ip_blkno);
            spin_unlock_irqrestore(&lockres->l_lock, flags);
            mlog_exit_void();
            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();
      }

      /* data and rw locking ignores refresh flag for now. */
      if (lockres->l_type != OCFS2_LOCK_TYPE_META)
            lockres_clear_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);

      /* set it to something invalid so if we get called again we
       * can catch it. */
      lockres->l_action = OCFS2_AST_INVALID;
      spin_unlock_irqrestore(&lockres->l_lock, flags);
      wake_up(&lockres->l_event);

      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_generic_bast_func(struct ocfs2_super *osb,
                            struct ocfs2_lock_res *lockres,
                            int level)
{
      int needs_downconvert;
      unsigned long flags;

      mlog_entry_void();

      BUG_ON(level <= LKM_NLMODE);

      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);

      ocfs2_kick_vote_thread(osb);

      wake_up(&lockres->l_event);
      mlog_exit_void();
}

static void ocfs2_inode_bast_func(void *opaque, int level)
{
      struct ocfs2_lock_res *lockres = opaque;
      struct inode *inode;
      struct ocfs2_super *osb;

      mlog_entry_void();

      BUG_ON(!ocfs2_is_inode_lock(lockres));

      inode = ocfs2_lock_res_inode(lockres);
      osb = OCFS2_SB(inode->i_sb);

      mlog(0, "BAST fired for inode %llu, blocking %d, level %d type %s\n",
           (unsigned long long)OCFS2_I(inode)->ip_blkno, level,
           lockres->l_level, ocfs2_lock_type_string(lockres->l_type));

      ocfs2_generic_bast_func(osb, lockres, level);

      mlog_exit_void();
}

static void ocfs2_generic_ast_func(struct ocfs2_lock_res *lockres,
                           int ignore_refresh)
{
      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);
            break;
      case OCFS2_AST_CONVERT:
            ocfs2_generic_handle_convert_action(lockres);
            break;
      case OCFS2_AST_DOWNCONVERT:
            ocfs2_generic_handle_downconvert_action(lockres);
            break;
      default:
            BUG();
      }

      if (ignore_refresh)
            lockres_clear_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);

      /* set it to something invalid so if we get called again we
       * can catch it. */
      lockres->l_action = OCFS2_AST_INVALID;
      spin_unlock_irqrestore(&lockres->l_lock, flags);

      wake_up(&lockres->l_event);
}

static void ocfs2_super_ast_func(void *opaque)
{
      struct ocfs2_lock_res *lockres = opaque;

      mlog_entry_void();
      mlog(0, "Superblock AST fired\n");

      BUG_ON(!ocfs2_is_super_lock(lockres));
      ocfs2_generic_ast_func(lockres, 0);

      mlog_exit_void();
}

static void ocfs2_super_bast_func(void *opaque,
                          int level)
{
      struct ocfs2_lock_res *lockres = opaque;
      struct ocfs2_super *osb;

      mlog_entry_void();
      mlog(0, "Superblock BAST fired\n");

      BUG_ON(!ocfs2_is_super_lock(lockres));
            osb = ocfs2_lock_res_super(lockres);
      ocfs2_generic_bast_func(osb, lockres, level);

      mlog_exit_void();
}

static void ocfs2_rename_ast_func(void *opaque)
{
      struct ocfs2_lock_res *lockres = opaque;

      mlog_entry_void();

      mlog(0, "Rename AST fired\n");

      BUG_ON(!ocfs2_is_rename_lock(lockres));

      ocfs2_generic_ast_func(lockres, 1);

      mlog_exit_void();
}

static void ocfs2_rename_bast_func(void *opaque,
                           int level)
{
      struct ocfs2_lock_res *lockres = opaque;
      struct ocfs2_super *osb;

      mlog_entry_void();

      mlog(0, "Rename BAST fired\n");

      BUG_ON(!ocfs2_is_rename_lock(lockres));

      osb = ocfs2_lock_res_super(lockres);
      ocfs2_generic_bast_func(osb, lockres, level);

      mlog_exit_void();
}

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;
      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,
                   lockres->l_ops->ast,
                   lockres,
                   lockres->l_ops->bast);
      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);

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|LKM_VALBLK,
                         lockres->l_name,
                         lockres->l_ops->ast,
                         lockres,
                         lockres->l_ops->bast);
            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_inode_lock(struct inode *inode,
                               struct ocfs2_lock_res *lockres)
{
      struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
      unsigned long flags;

      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, LKM_EXMODE, LKM_LOCAL);
}

/* 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;

      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_inode_lock(inode,
                                &OCFS2_I(inode)->ip_rw_lockres);
      if (ret) {
            mlog_errno(ret);
            goto bail;
      }

      ret = ocfs2_create_new_inode_lock(inode,
                                &OCFS2_I(inode)->ip_meta_lockres);
      if (ret) {
            mlog_errno(ret);
            goto bail;
      }

      ret = ocfs2_create_new_inode_lock(inode,
                                &OCFS2_I(inode)->ip_data_lockres);
      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;

      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");

      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;

      mlog_entry_void();

      mlog(0, "inode %llu drop %s RW lock\n",
           (unsigned long long)OCFS2_I(inode)->ip_blkno,
           write ? "EXMODE" : "PRMODE");

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

      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;

      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;
      }

      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;

      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_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;

      lvb->lvb_version   = cpu_to_be32(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));

      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));

      /* fast-symlinks are a special case */
      if (S_ISLNK(inode->i_mode) && !oi->ip_clusters)
            inode->i_blocks = 0;
      else
            inode->i_blocks =
                  ocfs2_align_bytes_to_sectors(i_size_read(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 ocfs2_lock_res *lockres)
{
      struct ocfs2_meta_lvb *lvb = (struct ocfs2_meta_lvb *) lockres->l_lksb.lvb;

      if (be32_to_cpu(lvb->lvb_version) == OCFS2_LVB_VERSION)
            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;
      struct ocfs2_dinode *fe;

      mlog_entry_void();

      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);

      lockres = &oi->ip_meta_lockres;

      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);

      /* will do nothing for inode types that don't use the extent
       * map (directories, bitmap files, etc) */
      ocfs2_extent_map_trunc(inode, 0);

      if (ocfs2_meta_lvb_is_trustable(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 ocfs2_journal_handle *handle,
                   struct buffer_head **ret_bh,
                   int ex,
                   int arg_flags)
{
      int status, level, dlm_flags, acquired;
      struct ocfs2_lock_res *lockres;
      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 (!(arg_flags & OCFS2_META_LOCK_RECOVERY))
            wait_event(osb->recovery_event,
                     ocfs2_node_map_is_empty(osb, &osb->recovery_map));

      acquired = 0;
      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));

      /* 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;
            }
      }

      if (handle) {
            status = ocfs2_handle_add_lock(handle, inode);
            if (status < 0)
                  mlog_errno(status);
      }

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 ocfs2_journal_handle *handle,
                        struct buffer_head **ret_bh,
                        int ex,
                        struct page *page)
{
      int ret;

      ret = ocfs2_meta_lock_full(inode, handle, ret_bh, ex,
                           OCFS2_LOCK_NONBLOCK);
      if (ret == -EAGAIN) {
            unlock_page(page);
            if (ocfs2_meta_lock(inode, handle, ret_bh, ex) == 0)
                  ocfs2_meta_unlock(inode, ex);
            ret = AOP_TRUNCATED_PAGE;
      }

      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;

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

      mlog_exit_void();
}

int ocfs2_super_lock(struct ocfs2_super *osb,
                 int ex)
{
      int status;
      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;

      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;

      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;

      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;

      ocfs2_cluster_unlock(osb, lockres, LKM_EXMODE);
}

/* 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"
               "%.*s\t"
               "%d\t"
               "0x%lx\t"
               "0x%x\t"
               "0x%x\t"
               "%u\t"
               "%u\t"
               "%d\t"
               "%d\t",
               OCFS2_DLM_DEBUG_STR_VERSION,
               OCFS2_LOCK_ID_MAX_LEN, lockres->l_name,
               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 = (struct ocfs2_super *) inode->u.generic_ip;
      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;
      u32 dlm_key;
      struct dlm_ctxt *dlm;

      mlog_entry_void();

      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;
      }

      ocfs2_super_lock_res_init(&osb->osb_super_lockres, osb);
      ocfs2_rename_lock_res_init(&osb->osb_rename_lockres, osb);

      dlm_register_eviction_cb(dlm, &osb->osb_eviction_cb);

      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_func(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();
}

typedef void (ocfs2_pre_drop_cb_t)(struct ocfs2_lock_res *, void *);

struct drop_lock_cb {
      ocfs2_pre_drop_cb_t     *drop_func;
      void              *drop_data;
};

static int ocfs2_drop_lock(struct ocfs2_super *osb,
                     struct ocfs2_lock_res *lockres,
                     struct drop_lock_cb *dcb)
{
      enum dlm_status status;
      unsigned long flags;

      /* We didn't get anywhere near actually using this lockres. */
      if (!(lockres->l_flags & OCFS2_LOCK_INITIALIZED))
            goto out;

      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 (dcb)
            dcb->drop_func(lockres, dcb->drop_data);

      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_VALBLK,
                     lockres->l_ops->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);
}

static void ocfs2_drop_osb_locks(struct ocfs2_super *osb)
{
      int status;

      mlog_entry_void();

      ocfs2_mark_lockres_freeing(&osb->osb_super_lockres);

      status = ocfs2_drop_lock(osb, &osb->osb_super_lockres, NULL);
      if (status < 0)
            mlog_errno(status);

      ocfs2_mark_lockres_freeing(&osb->osb_rename_lockres);

      status = ocfs2_drop_lock(osb, &osb->osb_rename_lockres, NULL);
      if (status < 0)
            mlog_errno(status);

      mlog_exit(status);
}

static void ocfs2_meta_pre_drop(struct ocfs2_lock_res *lockres, void *data)
{
      struct inode *inode = data;

      /* the metadata lock requires a bit more work as we have an
       * LVB to worry about. */
      if (lockres->l_flags & OCFS2_LOCK_ATTACHED &&
          lockres->l_level == LKM_EXMODE &&
          !(lockres->l_flags & OCFS2_LOCK_NEEDS_REFRESH))
            __ocfs2_stuff_meta_lvb(inode);
}

int ocfs2_drop_inode_locks(struct inode *inode)
{
      int status, err;
      struct drop_lock_cb meta_dcb = { ocfs2_meta_pre_drop, inode, };

      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_data_lockres,
                        NULL);
      if (err < 0)
            mlog_errno(err);

      status = err;

      err = ocfs2_drop_lock(OCFS2_SB(inode->i_sb),
                        &OCFS2_I(inode)->ip_meta_lockres,
                        &meta_dcb);
      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,
                        NULL);
      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,
                   lockres->l_ops->ast,
                   lockres,
                   lockres->l_ops->bast);
      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,
                     lockres->l_ops->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 inline int ocfs2_can_downconvert_meta_lock(struct inode *inode,
                                      struct ocfs2_lock_res *lockres,
                                      int new_level)
{
      int ret;

      mlog_entry_void();

      BUG_ON(new_level != LKM_NLMODE && new_level != LKM_PRMODE);

      if (lockres->l_flags & OCFS2_LOCK_REFRESHING) {
            ret = 0;
            mlog(0, "lockres %s currently being refreshed -- backing "
                 "off!\n", lockres->l_name);
      } else if (new_level == LKM_PRMODE)
            ret = !lockres->l_ex_holders &&
                  ocfs2_inode_fully_checkpointed(inode);
      else /* Must be NLMODE we're converting to. */
            ret = !lockres->l_ro_holders && !lockres->l_ex_holders &&
                  ocfs2_inode_fully_checkpointed(inode);

      mlog_exit(ret);
      return ret;
}

static int ocfs2_do_unblock_meta(struct inode *inode,
                         int *requeue)
{
      int new_level;
      int set_lvb = 0;
      int ret = 0;
      struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_meta_lockres;
      unsigned long flags;

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

      mlog_entry_void();

      spin_lock_irqsave(&lockres->l_lock, flags);

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

      mlog(0, "l_level=%d, l_blocking=%d\n", lockres->l_level,
           lockres->l_blocking);

      BUG_ON(lockres->l_level != LKM_EXMODE &&
             lockres->l_level != LKM_PRMODE);

      if (lockres->l_flags & OCFS2_LOCK_BUSY) {
            *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;
      }

      new_level = ocfs2_highest_compat_lock_level(lockres->l_blocking);

      mlog(0, "l_level=%d, l_blocking=%d, new_level=%d\n",
           lockres->l_level, lockres->l_blocking, new_level);

      if (ocfs2_can_downconvert_meta_lock(inode, lockres, new_level)) {
            if (lockres->l_level == LKM_EXMODE)
                  set_lvb = 1;

            /* If the lock hasn't been refreshed yet (rare), then
             * our memory inode values are old and we skip
             * stuffing the lvb. There's no need to actually clear
             * out the lvb here as it's value is still valid. */
            if (!(lockres->l_flags & OCFS2_LOCK_NEEDS_REFRESH)) {
                  if (set_lvb)
                        __ocfs2_stuff_meta_lvb(inode);
            } else
                  mlog(0, "lockres %s: downconverting stale lock!\n",
                       lockres->l_name);

            mlog(0, "calling ocfs2_downconvert_lock with l_level=%d, "
                 "l_blocking=%d, new_level=%d\n",
                 lockres->l_level, lockres->l_blocking, new_level);

            ocfs2_prepare_downconvert(lockres, new_level);
            spin_unlock_irqrestore(&lockres->l_lock, flags);
            ret = ocfs2_downconvert_lock(osb, lockres, new_level, set_lvb);
            goto leave;
      }
      if (!ocfs2_inode_fully_checkpointed(inode))
            ocfs2_start_checkpoint(osb);

      *requeue = 1;
      spin_unlock_irqrestore(&lockres->l_lock, flags);
      ret = 0;
leave:
      mlog_exit(ret);
      return ret;
}

static int ocfs2_generic_unblock_lock(struct ocfs2_super *osb,
                              struct ocfs2_lock_res *lockres,
                              int *requeue,
                              ocfs2_convert_worker_t *worker)
{
      unsigned long flags;
      int blocking;
      int new_level;
      int ret = 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) {
            *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)) {
            spin_unlock_irqrestore(&lockres->l_lock, flags);
            *requeue = 1;
            ret = 0;
            goto leave;
      }

      /* 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) {
            spin_unlock_irqrestore(&lockres->l_lock, flags);
            *requeue = 1;
            ret = 0;
            goto leave;
      }

      /* 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 (!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);

      worker(lockres, blocking);

      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:
      *requeue = 0;
      new_level = ocfs2_highest_compat_lock_level(lockres->l_blocking);

      ocfs2_prepare_downconvert(lockres, new_level);
      spin_unlock_irqrestore(&lockres->l_lock, flags);
      ret = ocfs2_downconvert_lock(osb, lockres, new_level, 0);
leave:
      mlog_exit(ret);
      return ret;
}

static void ocfs2_data_convert_worker(struct ocfs2_lock_res *lockres,
                              int blocking)
{
      struct inode *inode;
      struct address_space *mapping;

      mlog_entry_void();

            inode = ocfs2_lock_res_inode(lockres);
      mapping = inode->i_mapping;

      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);
            unmap_mapping_range(mapping, 0, 0, 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);
      }

      mlog_exit_void();
}

int ocfs2_unblock_data(struct ocfs2_lock_res *lockres,
                   int *requeue)
{
      int status;
      struct inode *inode;
      struct ocfs2_super *osb;

      mlog_entry_void();

      inode = ocfs2_lock_res_inode(lockres);
      osb = OCFS2_SB(inode->i_sb);

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

      status = ocfs2_generic_unblock_lock(osb,
                                  lockres,
                                  requeue,
                                  ocfs2_data_convert_worker);
      if (status < 0)
            mlog_errno(status);

      mlog(0, "inode %llu, requeue = %d\n",
           (unsigned long long)OCFS2_I(inode)->ip_blkno, *requeue);

      mlog_exit(status);
      return status;
}

static int ocfs2_unblock_inode_lock(struct ocfs2_lock_res *lockres,
                            int *requeue)
{
      int status;
      struct inode *inode;

      mlog_entry_void();

      mlog(0, "Unblock lockres %s\n", lockres->l_name);

      inode  = ocfs2_lock_res_inode(lockres);

      status = ocfs2_generic_unblock_lock(OCFS2_SB(inode->i_sb),
                                  lockres,
                                  requeue,
                                  NULL);
      if (status < 0)
            mlog_errno(status);

      mlog_exit(status);
      return status;
}


int ocfs2_unblock_meta(struct ocfs2_lock_res *lockres,
                   int *requeue)
{
      int status;
      struct inode *inode;

      mlog_entry_void();

            inode = ocfs2_lock_res_inode(lockres);

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

      status = ocfs2_do_unblock_meta(inode, requeue);
      if (status < 0)
            mlog_errno(status);

      mlog(0, "inode %llu, requeue = %d\n",
           (unsigned long long)OCFS2_I(inode)->ip_blkno, *requeue);

      mlog_exit(status);
      return status;
}

/* Generic unblock function for any lockres whose private data is an
 * ocfs2_super pointer. */
static int ocfs2_unblock_osb_lock(struct ocfs2_lock_res *lockres,
                          int *requeue)
{
      int status;
      struct ocfs2_super *osb;

      mlog_entry_void();

      mlog(0, "Unblock lockres %s\n", lockres->l_name);

      osb = ocfs2_lock_res_super(lockres);

      status = ocfs2_generic_unblock_lock(osb,
                                  lockres,
                                  requeue,
                                  NULL);
      if (status < 0)
            mlog_errno(status);

      mlog_exit(status);
      return status;
}

void ocfs2_process_blocked_lock(struct ocfs2_super *osb,
                        struct ocfs2_lock_res *lockres)
{
      int status;
      int requeue = 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);
      BUG_ON(!lockres->l_ops->unblock);

      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 = lockres->l_ops->unblock(lockres, &requeue);
      if (status < 0)
            mlog_errno(status);

      spin_lock_irqsave(&lockres->l_lock, flags);
unqueue:
      if (lockres->l_flags & OCFS2_LOCK_FREEING || !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,
           requeue ? "yes" : "no");
      spin_unlock_irqrestore(&lockres->l_lock, flags);

      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();
}

/* This aids in debugging situations where a bad LVB might be involved. */
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\n",
           be32_to_cpu(lvb->lvb_version), be32_to_cpu(lvb->lvb_iclusters));
      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\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));
}

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