TOMOYO Linux Cross Reference
Linux/fs/ocfs2/dlmglue.c

   // SPDX-License-Identifier: GPL-2.0-or-later
   /*
    * dlmglue.c
    *
    * Code which implements an OCFS2 specific interface to our DLM.
    *
    * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
    */
   
  #include <linux/types.h>
  #include <linux/slab.h>
  #include <linux/highmem.h>
  #include <linux/mm.h>
  #include <linux/kthread.h>
  #include <linux/pagemap.h>
  #include <linux/debugfs.h>
  #include <linux/seq_file.h>
  #include <linux/time.h>
  #include <linux/delay.h>
  #include <linux/quotaops.h>
  #include <linux/sched/signal.h>
  
  #define MLOG_MASK_PREFIX ML_DLM_GLUE
  #include <cluster/masklog.h>
  
  #include "ocfs2.h"
  #include "ocfs2_lockingver.h"
  
  #include "alloc.h"
  #include "dcache.h"
  #include "dlmglue.h"
  #include "extent_map.h"
  #include "file.h"
  #include "heartbeat.h"
  #include "inode.h"
  #include "journal.h"
  #include "stackglue.h"
  #include "slot_map.h"
  #include "super.h"
  #include "uptodate.h"
  #include "quota.h"
  #include "refcounttree.h"
  #include "acl.h"
  
  #include "buffer_head_io.h"
  
  struct ocfs2_mask_waiter {
          struct list_head        mw_item;
          int                     mw_status;
          struct completion       mw_complete;
          unsigned long           mw_mask;
          unsigned long           mw_goal;
  #ifdef CONFIG_OCFS2_FS_STATS
          ktime_t                 mw_lock_start;
  #endif
  };
  
  static struct ocfs2_super *ocfs2_get_dentry_osb(struct ocfs2_lock_res *lockres);
  static struct ocfs2_super *ocfs2_get_inode_osb(struct ocfs2_lock_res *lockres);
  static struct ocfs2_super *ocfs2_get_file_osb(struct ocfs2_lock_res *lockres);
  static struct ocfs2_super *ocfs2_get_qinfo_osb(struct ocfs2_lock_res *lockres);
  
  /*
   * Return value from ->downconvert_worker functions.
   *
   * These control the precise actions of ocfs2_unblock_lock()
   * and ocfs2_process_blocked_lock()
   *
   */
  enum ocfs2_unblock_action {
          UNBLOCK_CONTINUE        = 0, /* Continue downconvert */
          UNBLOCK_CONTINUE_POST   = 1, /* Continue downconvert, fire
                                        * ->post_unlock callback */
          UNBLOCK_STOP_POST       = 2, /* Do not downconvert, fire
                                        * ->post_unlock() callback. */
  };
  
  struct ocfs2_unblock_ctl {
          int requeue;
          enum ocfs2_unblock_action unblock_action;
  };
  
  /* Lockdep class keys */
  #ifdef CONFIG_DEBUG_LOCK_ALLOC
  static struct lock_class_key lockdep_keys[OCFS2_NUM_LOCK_TYPES];
  #endif
  
  static int ocfs2_check_meta_downconvert(struct ocfs2_lock_res *lockres,
                                          int new_level);
  static void ocfs2_set_meta_lvb(struct ocfs2_lock_res *lockres);
  
  static int ocfs2_data_convert_worker(struct ocfs2_lock_res *lockres,
                                       int blocking);
  
  static int ocfs2_dentry_convert_worker(struct ocfs2_lock_res *lockres,
                                         int blocking);
  
  static void ocfs2_dentry_post_unlock(struct ocfs2_super *osb,
                                       struct ocfs2_lock_res *lockres);
 
 static void ocfs2_set_qinfo_lvb(struct ocfs2_lock_res *lockres);
 
 static int ocfs2_check_refcount_downconvert(struct ocfs2_lock_res *lockres,
                                             int new_level);
 static int ocfs2_refcount_convert_worker(struct ocfs2_lock_res *lockres,
                                          int blocking);
 
 #define mlog_meta_lvb(__level, __lockres) ocfs2_dump_meta_lvb_info(__level, __PRETTY_FUNCTION__, __LINE__, __lockres)
 
 /* This aids in debugging situations where a bad LVB might be involved. */
 static void ocfs2_dump_meta_lvb_info(u64 level,
                                      const char *function,
                                      unsigned int line,
                                      struct ocfs2_lock_res *lockres)
 {
         struct ocfs2_meta_lvb *lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
 
         mlog(level, "LVB information for %s (called from %s:%u):\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 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 const struct ocfs2_lock_res_ops ocfs2_inode_rw_lops = {
         .get_osb        = ocfs2_get_inode_osb,
         .flags          = 0,
 };
 
 static const struct ocfs2_lock_res_ops ocfs2_inode_inode_lops = {
         .get_osb        = ocfs2_get_inode_osb,
         .check_downconvert = ocfs2_check_meta_downconvert,
         .set_lvb        = ocfs2_set_meta_lvb,
         .downconvert_worker = ocfs2_data_convert_worker,
         .flags          = LOCK_TYPE_REQUIRES_REFRESH|LOCK_TYPE_USES_LVB,
 };
 
 static const struct ocfs2_lock_res_ops ocfs2_super_lops = {
         .flags          = LOCK_TYPE_REQUIRES_REFRESH,
 };
 
 static const struct ocfs2_lock_res_ops ocfs2_rename_lops = {
         .flags          = 0,
 };
 
 static const struct ocfs2_lock_res_ops ocfs2_nfs_sync_lops = {
         .flags          = 0,
 };
 
 static const struct ocfs2_lock_res_ops ocfs2_trim_fs_lops = {
         .flags          = LOCK_TYPE_REQUIRES_REFRESH|LOCK_TYPE_USES_LVB,
 };
 
 static const struct ocfs2_lock_res_ops ocfs2_orphan_scan_lops = {
         .flags          = LOCK_TYPE_REQUIRES_REFRESH|LOCK_TYPE_USES_LVB,
 };
 
 static const 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 const struct ocfs2_lock_res_ops ocfs2_inode_open_lops = {
         .get_osb        = ocfs2_get_inode_osb,
         .flags          = 0,
 };
 
 static const struct ocfs2_lock_res_ops ocfs2_flock_lops = {
         .get_osb        = ocfs2_get_file_osb,
         .flags          = 0,
 };
 
 static const struct ocfs2_lock_res_ops ocfs2_qinfo_lops = {
         .set_lvb        = ocfs2_set_qinfo_lvb,
         .get_osb        = ocfs2_get_qinfo_osb,
         .flags          = LOCK_TYPE_REQUIRES_REFRESH | LOCK_TYPE_USES_LVB,
 };
 
 static const struct ocfs2_lock_res_ops ocfs2_refcount_block_lops = {
         .check_downconvert = ocfs2_check_refcount_downconvert,
         .downconvert_worker = ocfs2_refcount_convert_worker,
         .flags          = 0,
 };
 
 static inline int ocfs2_is_inode_lock(struct ocfs2_lock_res *lockres)
 {
         return lockres->l_type == OCFS2_LOCK_TYPE_META ||
                 lockres->l_type == OCFS2_LOCK_TYPE_RW ||
                 lockres->l_type == OCFS2_LOCK_TYPE_OPEN;
 }
 
 static inline struct ocfs2_lock_res *ocfs2_lksb_to_lock_res(struct ocfs2_dlm_lksb *lksb)
 {
         return container_of(lksb, struct ocfs2_lock_res, l_lksb);
 }
 
 static inline struct inode *ocfs2_lock_res_inode(struct ocfs2_lock_res *lockres)
 {
         BUG_ON(!ocfs2_is_inode_lock(lockres));
 
         return (struct inode *) lockres->l_priv;
 }
 
 static inline struct ocfs2_dentry_lock *ocfs2_lock_res_dl(struct ocfs2_lock_res *lockres)
 {
         BUG_ON(lockres->l_type != OCFS2_LOCK_TYPE_DENTRY);
 
         return (struct ocfs2_dentry_lock *)lockres->l_priv;
 }
 
 static inline struct ocfs2_mem_dqinfo *ocfs2_lock_res_qinfo(struct ocfs2_lock_res *lockres)
 {
         BUG_ON(lockres->l_type != OCFS2_LOCK_TYPE_QINFO);
 
         return (struct ocfs2_mem_dqinfo *)lockres->l_priv;
 }
 
 static inline struct ocfs2_refcount_tree *
 ocfs2_lock_res_refcount_tree(struct ocfs2_lock_res *res)
 {
         return container_of(res, struct ocfs2_refcount_tree, rf_lockres);
 }
 
 static inline struct ocfs2_super *ocfs2_get_lockres_osb(struct ocfs2_lock_res *lockres)
 {
         if (lockres->l_ops->get_osb)
                 return lockres->l_ops->get_osb(lockres);
 
         return (struct ocfs2_super *)lockres->l_priv;
 }
 
 static int ocfs2_lock_create(struct ocfs2_super *osb,
                              struct ocfs2_lock_res *lockres,
                              int level,
                              u32 dlm_flags);
 static inline int ocfs2_may_continue_on_blocked_lock(struct ocfs2_lock_res *lockres,
                                                      int wanted);
 static void __ocfs2_cluster_unlock(struct ocfs2_super *osb,
                                    struct ocfs2_lock_res *lockres,
                                    int level, unsigned long caller_ip);
 static inline void ocfs2_cluster_unlock(struct ocfs2_super *osb,
                                         struct ocfs2_lock_res *lockres,
                                         int level)
 {
         __ocfs2_cluster_unlock(osb, lockres, level, _RET_IP_);
 }
 
 static inline void ocfs2_generic_handle_downconvert_action(struct ocfs2_lock_res *lockres);
 static inline void ocfs2_generic_handle_convert_action(struct ocfs2_lock_res *lockres);
 static inline void ocfs2_generic_handle_attach_action(struct ocfs2_lock_res *lockres);
 static int ocfs2_generic_handle_bast(struct ocfs2_lock_res *lockres, int level);
 static void ocfs2_schedule_blocked_lock(struct ocfs2_super *osb,
                                         struct ocfs2_lock_res *lockres);
 static inline void ocfs2_recover_from_dlm_error(struct ocfs2_lock_res *lockres,
                                                 int convert);
 #define ocfs2_log_dlm_error(_func, _err, _lockres) do {                                 \
         if ((_lockres)->l_type != OCFS2_LOCK_TYPE_DENTRY)                               \
                 mlog(ML_ERROR, "DLM error %d while calling %s on resource %s\n",        \
                      _err, _func, _lockres->l_name);                                    \
         else                                                                            \
                 mlog(ML_ERROR, "DLM error %d while calling %s on resource %.*s%08x\n",  \
                      _err, _func, OCFS2_DENTRY_LOCK_INO_START - 1, (_lockres)->l_name,  \
                      (unsigned int)ocfs2_get_dentry_lock_ino(_lockres));                \
 } while (0)
 static int ocfs2_downconvert_thread(void *arg);
 static void ocfs2_downconvert_on_unlock(struct ocfs2_super *osb,
                                         struct ocfs2_lock_res *lockres);
 static int ocfs2_inode_lock_update(struct inode *inode,
                                   struct buffer_head **bh);
 static void ocfs2_drop_osb_locks(struct ocfs2_super *osb);
 static inline int ocfs2_highest_compat_lock_level(int level);
 static unsigned int ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
                                               int new_level);
 static int ocfs2_downconvert_lock(struct ocfs2_super *osb,
                                   struct ocfs2_lock_res *lockres,
                                   int new_level,
                                   int lvb,
                                   unsigned int generation);
 static int ocfs2_prepare_cancel_convert(struct ocfs2_super *osb,
                                         struct ocfs2_lock_res *lockres);
 static int ocfs2_cancel_convert(struct ocfs2_super *osb,
                                 struct ocfs2_lock_res *lockres);
 
 
 static void ocfs2_build_lock_name(enum ocfs2_lock_type type,
                                   u64 blkno,
                                   u32 generation,
                                   char *name)
 {
         int len;
 
         BUG_ON(type >= OCFS2_NUM_LOCK_TYPES);
 
         len = snprintf(name, OCFS2_LOCK_ID_MAX_LEN, "%c%s%016llx%08x",
                        ocfs2_lock_type_char(type), OCFS2_LOCK_ID_PAD,
                        (long long)blkno, generation);
 
         BUG_ON(len != (OCFS2_LOCK_ID_MAX_LEN - 1));
 
         mlog(0, "built lock resource with name: %s\n", name);
 }
 
 static DEFINE_SPINLOCK(ocfs2_dlm_tracking_lock);
 
 static void ocfs2_add_lockres_tracking(struct ocfs2_lock_res *res,
                                        struct ocfs2_dlm_debug *dlm_debug)
 {
         mlog(0, "Add tracking for lockres %s\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);
 }
 
 #ifdef CONFIG_OCFS2_FS_STATS
 static void ocfs2_init_lock_stats(struct ocfs2_lock_res *res)
 {
         res->l_lock_refresh = 0;
         res->l_lock_wait = 0;
         memset(&res->l_lock_prmode, 0, sizeof(struct ocfs2_lock_stats));
         memset(&res->l_lock_exmode, 0, sizeof(struct ocfs2_lock_stats));
 }
 
 static void ocfs2_update_lock_stats(struct ocfs2_lock_res *res, int level,
                                     struct ocfs2_mask_waiter *mw, int ret)
 {
         u32 usec;
         ktime_t kt;
         struct ocfs2_lock_stats *stats;
 
         if (level == LKM_PRMODE)
                 stats = &res->l_lock_prmode;
         else if (level == LKM_EXMODE)
                 stats = &res->l_lock_exmode;
         else
                 return;
 
         kt = ktime_sub(ktime_get(), mw->mw_lock_start);
         usec = ktime_to_us(kt);
 
         stats->ls_gets++;
         stats->ls_total += ktime_to_ns(kt);
         /* overflow */
         if (unlikely(stats->ls_gets == 0)) {
                 stats->ls_gets++;
                 stats->ls_total = ktime_to_ns(kt);
         }
 
         if (stats->ls_max < usec)
                 stats->ls_max = usec;
 
         if (ret)
                 stats->ls_fail++;
 
         stats->ls_last = ktime_to_us(ktime_get_real());
 }
 
 static inline void ocfs2_track_lock_refresh(struct ocfs2_lock_res *lockres)
 {
         lockres->l_lock_refresh++;
 }
 
 static inline void ocfs2_track_lock_wait(struct ocfs2_lock_res *lockres)
 {
         struct ocfs2_mask_waiter *mw;
 
         if (list_empty(&lockres->l_mask_waiters)) {
                 lockres->l_lock_wait = 0;
                 return;
         }
 
         mw = list_first_entry(&lockres->l_mask_waiters,
                                 struct ocfs2_mask_waiter, mw_item);
         lockres->l_lock_wait =
                         ktime_to_us(ktime_mono_to_real(mw->mw_lock_start));
 }
 
 static inline void ocfs2_init_start_time(struct ocfs2_mask_waiter *mw)
 {
         mw->mw_lock_start = ktime_get();
 }
 #else
 static inline void ocfs2_init_lock_stats(struct ocfs2_lock_res *res)
 {
 }
 static inline void ocfs2_update_lock_stats(struct ocfs2_lock_res *res,
                            int level, struct ocfs2_mask_waiter *mw, int ret)
 {
 }
 static inline void ocfs2_track_lock_refresh(struct ocfs2_lock_res *lockres)
 {
 }
 static inline void ocfs2_track_lock_wait(struct ocfs2_lock_res *lockres)
 {
 }
 static inline void ocfs2_init_start_time(struct ocfs2_mask_waiter *mw)
 {
 }
 #endif
 
 static void ocfs2_lock_res_init_common(struct ocfs2_super *osb,
                                        struct ocfs2_lock_res *res,
                                        enum ocfs2_lock_type type,
                                        const struct ocfs2_lock_res_ops *ops,
                                        void *priv)
 {
         res->l_type          = type;
         res->l_ops           = ops;
         res->l_priv          = priv;
 
         res->l_level         = DLM_LOCK_IV;
         res->l_requested     = DLM_LOCK_IV;
         res->l_blocking      = DLM_LOCK_IV;
         res->l_action        = OCFS2_AST_INVALID;
         res->l_unlock_action = OCFS2_UNLOCK_INVALID;
 
         res->l_flags         = OCFS2_LOCK_INITIALIZED;
 
         ocfs2_add_lockres_tracking(res, osb->osb_dlm_debug);
 
         ocfs2_init_lock_stats(res);
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
         if (type != OCFS2_LOCK_TYPE_OPEN)
                 lockdep_init_map(&res->l_lockdep_map, ocfs2_lock_type_strings[type],
                                  &lockdep_keys[type], 0);
         else
                 res->l_lockdep_map.key = NULL;
 #endif
 }
 
 void ocfs2_lock_res_init_once(struct ocfs2_lock_res *res)
 {
         /* This also clears out the lock status block */
         memset(res, 0, sizeof(struct ocfs2_lock_res));
         spin_lock_init(&res->l_lock);
         init_waitqueue_head(&res->l_event);
         INIT_LIST_HEAD(&res->l_blocked_list);
         INIT_LIST_HEAD(&res->l_mask_waiters);
         INIT_LIST_HEAD(&res->l_holders);
 }
 
 void ocfs2_inode_lock_res_init(struct ocfs2_lock_res *res,
                                enum ocfs2_lock_type type,
                                unsigned int generation,
                                struct inode *inode)
 {
         const struct ocfs2_lock_res_ops *ops;
 
         switch(type) {
                 case OCFS2_LOCK_TYPE_RW:
                         ops = &ocfs2_inode_rw_lops;
                         break;
                 case OCFS2_LOCK_TYPE_META:
                         ops = &ocfs2_inode_inode_lops;
                         break;
                 case OCFS2_LOCK_TYPE_OPEN:
                         ops = &ocfs2_inode_open_lops;
                         break;
                 default:
                         mlog_bug_on_msg(1, "type: %d\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 struct ocfs2_super *ocfs2_get_qinfo_osb(struct ocfs2_lock_res *lockres)
 {
         struct ocfs2_mem_dqinfo *info = lockres->l_priv;
 
         return OCFS2_SB(info->dqi_gi.dqi_sb);
 }
 
 static struct ocfs2_super *ocfs2_get_file_osb(struct ocfs2_lock_res *lockres)
 {
         struct ocfs2_file_private *fp = lockres->l_priv;
 
         return OCFS2_SB(fp->fp_file->f_mapping->host->i_sb);
 }
 
 static __u64 ocfs2_get_dentry_lock_ino(struct ocfs2_lock_res *lockres)
 {
         __be64 inode_blkno_be;
 
         memcpy(&inode_blkno_be, &lockres->l_name[OCFS2_DENTRY_LOCK_INO_START],
                sizeof(__be64));
 
         return be64_to_cpu(inode_blkno_be);
 }
 
 static struct ocfs2_super *ocfs2_get_dentry_osb(struct ocfs2_lock_res *lockres)
 {
         struct ocfs2_dentry_lock *dl = lockres->l_priv;
 
         return OCFS2_SB(dl->dl_inode->i_sb);
 }
 
 void ocfs2_dentry_lock_res_init(struct ocfs2_dentry_lock *dl,
                                 u64 parent, struct inode *inode)
 {
         int len;
         u64 inode_blkno = OCFS2_I(inode)->ip_blkno;
         __be64 inode_blkno_be = cpu_to_be64(inode_blkno);
         struct ocfs2_lock_res *lockres = &dl->dl_lockres;
 
         ocfs2_lock_res_init_once(lockres);
 
         /*
          * Unfortunately, the standard lock naming scheme won't work
          * here because we have two 16 byte values to use. Instead,
          * we'll stuff the inode number as a binary value. We still
          * want error prints to show something without garbling the
          * display, so drop a null byte in there before the inode
          * number. A future version of OCFS2 will likely use all
          * binary lock names. The stringified names have been a
          * tremendous aid in debugging, but now that the debugfs
          * interface exists, we can mangle things there if need be.
          *
          * NOTE: We also drop the standard "pad" value (the total lock
          * name size stays the same though - the last part is all
          * zeros due to the memset in ocfs2_lock_res_init_once()
          */
         len = snprintf(lockres->l_name, OCFS2_DENTRY_LOCK_INO_START,
                        "%c%016llx",
                        ocfs2_lock_type_char(OCFS2_LOCK_TYPE_DENTRY),
                        (long long)parent);
 
         BUG_ON(len != (OCFS2_DENTRY_LOCK_INO_START - 1));
 
         memcpy(&lockres->l_name[OCFS2_DENTRY_LOCK_INO_START], &inode_blkno_be,
                sizeof(__be64));
 
         ocfs2_lock_res_init_common(OCFS2_SB(inode->i_sb), lockres,
                                    OCFS2_LOCK_TYPE_DENTRY, &ocfs2_dentry_lops,
                                    dl);
 }
 
 static void ocfs2_super_lock_res_init(struct ocfs2_lock_res *res,
                                       struct ocfs2_super *osb)
 {
         /* Superblock lockres doesn't come from a slab so we call init
          * once on it manually.  */
         ocfs2_lock_res_init_once(res);
         ocfs2_build_lock_name(OCFS2_LOCK_TYPE_SUPER, OCFS2_SUPER_BLOCK_BLKNO,
                               0, res->l_name);
         ocfs2_lock_res_init_common(osb, res, OCFS2_LOCK_TYPE_SUPER,
                                    &ocfs2_super_lops, osb);
 }
 
 static void ocfs2_rename_lock_res_init(struct ocfs2_lock_res *res,
                                        struct ocfs2_super *osb)
 {
         /* Rename lockres doesn't come from a slab so we call init
          * once on it manually.  */
         ocfs2_lock_res_init_once(res);
         ocfs2_build_lock_name(OCFS2_LOCK_TYPE_RENAME, 0, 0, res->l_name);
         ocfs2_lock_res_init_common(osb, res, OCFS2_LOCK_TYPE_RENAME,
                                    &ocfs2_rename_lops, osb);
 }
 
 static void ocfs2_nfs_sync_lock_res_init(struct ocfs2_lock_res *res,
                                          struct ocfs2_super *osb)
 {
         /* nfs_sync lockres doesn't come from a slab so we call init
          * once on it manually.  */
         ocfs2_lock_res_init_once(res);
         ocfs2_build_lock_name(OCFS2_LOCK_TYPE_NFS_SYNC, 0, 0, res->l_name);
         ocfs2_lock_res_init_common(osb, res, OCFS2_LOCK_TYPE_NFS_SYNC,
                                    &ocfs2_nfs_sync_lops, osb);
 }
 
 static void ocfs2_nfs_sync_lock_init(struct ocfs2_super *osb)
 {
         ocfs2_nfs_sync_lock_res_init(&osb->osb_nfs_sync_lockres, osb);
         init_rwsem(&osb->nfs_sync_rwlock);
 }
 
 void ocfs2_trim_fs_lock_res_init(struct ocfs2_super *osb)
 {
         struct ocfs2_lock_res *lockres = &osb->osb_trim_fs_lockres;
 
         /* Only one trimfs thread are allowed to work at the same time. */
         mutex_lock(&osb->obs_trim_fs_mutex);
 
         ocfs2_lock_res_init_once(lockres);
         ocfs2_build_lock_name(OCFS2_LOCK_TYPE_TRIM_FS, 0, 0, lockres->l_name);
         ocfs2_lock_res_init_common(osb, lockres, OCFS2_LOCK_TYPE_TRIM_FS,
                                    &ocfs2_trim_fs_lops, osb);
 }
 
 void ocfs2_trim_fs_lock_res_uninit(struct ocfs2_super *osb)
 {
         struct ocfs2_lock_res *lockres = &osb->osb_trim_fs_lockres;
 
         ocfs2_simple_drop_lockres(osb, lockres);
         ocfs2_lock_res_free(lockres);
 
         mutex_unlock(&osb->obs_trim_fs_mutex);
 }
 
 static void ocfs2_orphan_scan_lock_res_init(struct ocfs2_lock_res *res,
                                             struct ocfs2_super *osb)
 {
         ocfs2_lock_res_init_once(res);
         ocfs2_build_lock_name(OCFS2_LOCK_TYPE_ORPHAN_SCAN, 0, 0, res->l_name);
         ocfs2_lock_res_init_common(osb, res, OCFS2_LOCK_TYPE_ORPHAN_SCAN,
                                    &ocfs2_orphan_scan_lops, osb);
 }
 
 void ocfs2_file_lock_res_init(struct ocfs2_lock_res *lockres,
                               struct ocfs2_file_private *fp)
 {
         struct inode *inode = fp->fp_file->f_mapping->host;
         struct ocfs2_inode_info *oi = OCFS2_I(inode);
 
         ocfs2_lock_res_init_once(lockres);
         ocfs2_build_lock_name(OCFS2_LOCK_TYPE_FLOCK, oi->ip_blkno,
                               inode->i_generation, lockres->l_name);
         ocfs2_lock_res_init_common(OCFS2_SB(inode->i_sb), lockres,
                                    OCFS2_LOCK_TYPE_FLOCK, &ocfs2_flock_lops,
                                    fp);
         lockres->l_flags |= OCFS2_LOCK_NOCACHE;
 }
 
 void ocfs2_qinfo_lock_res_init(struct ocfs2_lock_res *lockres,
                                struct ocfs2_mem_dqinfo *info)
 {
         ocfs2_lock_res_init_once(lockres);
         ocfs2_build_lock_name(OCFS2_LOCK_TYPE_QINFO, info->dqi_gi.dqi_type,
                               0, lockres->l_name);
         ocfs2_lock_res_init_common(OCFS2_SB(info->dqi_gi.dqi_sb), lockres,
                                    OCFS2_LOCK_TYPE_QINFO, &ocfs2_qinfo_lops,
                                    info);
 }
 
 void ocfs2_refcount_lock_res_init(struct ocfs2_lock_res *lockres,
                                   struct ocfs2_super *osb, u64 ref_blkno,
                                   unsigned int generation)
 {
         ocfs2_lock_res_init_once(lockres);
         ocfs2_build_lock_name(OCFS2_LOCK_TYPE_REFCOUNT, ref_blkno,
                               generation, lockres->l_name);
         ocfs2_lock_res_init_common(osb, lockres, OCFS2_LOCK_TYPE_REFCOUNT,
                                    &ocfs2_refcount_block_lops, osb);
 }
 
 void ocfs2_lock_res_free(struct ocfs2_lock_res *res)
 {
         if (!(res->l_flags & OCFS2_LOCK_INITIALIZED))
                 return;
 
         ocfs2_remove_lockres_tracking(res);
 
         mlog_bug_on_msg(!list_empty(&res->l_blocked_list),
                         "Lockres %s is on the blocked list\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;
 }
 
 /*
  * Keep a list of processes who have interest in a lockres.
  * Note: this is now only uesed for check recursive cluster locking.
  */
 static inline void ocfs2_add_holder(struct ocfs2_lock_res *lockres,
                                    struct ocfs2_lock_holder *oh)
 {
         INIT_LIST_HEAD(&oh->oh_list);
         oh->oh_owner_pid = get_pid(task_pid(current));
 
         spin_lock(&lockres->l_lock);
         list_add_tail(&oh->oh_list, &lockres->l_holders);
         spin_unlock(&lockres->l_lock);
 }
 
 static struct ocfs2_lock_holder *
 ocfs2_pid_holder(struct ocfs2_lock_res *lockres,
                 struct pid *pid)
 {
         struct ocfs2_lock_holder *oh;
 
         spin_lock(&lockres->l_lock);
         list_for_each_entry(oh, &lockres->l_holders, oh_list) {
                 if (oh->oh_owner_pid == pid) {
                         spin_unlock(&lockres->l_lock);
                         return oh;
                 }
         }
         spin_unlock(&lockres->l_lock);
         return NULL;
 }
 
 static inline void ocfs2_remove_holder(struct ocfs2_lock_res *lockres,
                                        struct ocfs2_lock_holder *oh)
 {
         spin_lock(&lockres->l_lock);
         list_del(&oh->oh_list);
         spin_unlock(&lockres->l_lock);
 
         put_pid(oh->oh_owner_pid);
 }
 
 
 static inline void ocfs2_inc_holders(struct ocfs2_lock_res *lockres,
                                      int level)
 {
         BUG_ON(!lockres);
 
         switch(level) {
         case DLM_LOCK_EX:
                 lockres->l_ex_holders++;
                 break;
         case DLM_LOCK_PR:
                 lockres->l_ro_holders++;
                 break;
         default:
                 BUG();
         }
 }
 
 static inline void ocfs2_dec_holders(struct ocfs2_lock_res *lockres,
                                      int level)
 {
         BUG_ON(!lockres);
 
         switch(level) {
         case DLM_LOCK_EX:
                 BUG_ON(!lockres->l_ex_holders);
                 lockres->l_ex_holders--;
                 break;
         case DLM_LOCK_PR:
                 BUG_ON(!lockres->l_ro_holders);
                 lockres->l_ro_holders--;
                 break;
         default:
                 BUG();
         }
 }
 
 /* WARNING: This function lives in a world where the only three lock
  * levels are EX, PR, and NL. It *will* have to be adjusted when more
  * lock types are added. */
 static inline int ocfs2_highest_compat_lock_level(int level)
 {
         int new_level = DLM_LOCK_EX;
 
         if (level == DLM_LOCK_EX)
                 new_level = DLM_LOCK_NL;
         else if (level == DLM_LOCK_PR)
                 new_level = DLM_LOCK_PR;
         return new_level;
 }
 
 static void lockres_set_flags(struct ocfs2_lock_res *lockres,
                               unsigned long newflags)
 {
         struct ocfs2_mask_waiter *mw, *tmp;
 
         assert_spin_locked(&lockres->l_lock);
 
         lockres->l_flags = newflags;
 
         list_for_each_entry_safe(mw, tmp, &lockres->l_mask_waiters, mw_item) {
                 if ((lockres->l_flags & mw->mw_mask) != mw->mw_goal)
                         continue;
 
                 list_del_init(&mw->mw_item);
                 mw->mw_status = 0;
                 complete(&mw->mw_complete);
                 ocfs2_track_lock_wait(lockres);
         }
 }
 static void lockres_or_flags(struct ocfs2_lock_res *lockres, unsigned long or)
 {
         lockres_set_flags(lockres, lockres->l_flags | or);
 }
 static void lockres_clear_flags(struct ocfs2_lock_res *lockres,
                                 unsigned long clear)
 {
         lockres_set_flags(lockres, lockres->l_flags & ~clear);
 }
 
 static inline void ocfs2_generic_handle_downconvert_action(struct ocfs2_lock_res *lockres)
 {
         BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BUSY));
         BUG_ON(!(lockres->l_flags & OCFS2_LOCK_ATTACHED));
         BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BLOCKED));
         BUG_ON(lockres->l_blocking <= DLM_LOCK_NL);
 
         lockres->l_level = lockres->l_requested;
         if (lockres->l_level <=
             ocfs2_highest_compat_lock_level(lockres->l_blocking)) {
                 lockres->l_blocking = DLM_LOCK_NL;
                 lockres_clear_flags(lockres, OCFS2_LOCK_BLOCKED);
         }
         lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
 }
 
 static inline void ocfs2_generic_handle_convert_action(struct ocfs2_lock_res *lockres)
 {
         BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BUSY));
         BUG_ON(!(lockres->l_flags & OCFS2_LOCK_ATTACHED));
 
         /* Convert from RO to EX doesn't really need anything as our
          * information is already up to data. Convert from NL to
          * *anything* however should mark ourselves as needing an
          * update */
         if (lockres->l_level == DLM_LOCK_NL &&
             lockres->l_ops->flags & LOCK_TYPE_REQUIRES_REFRESH)
                 lockres_or_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
 
         lockres->l_level = lockres->l_requested;
 
         /*
          * We set the OCFS2_LOCK_UPCONVERT_FINISHING flag before clearing
          * the OCFS2_LOCK_BUSY flag to prevent the dc thread from
          * downconverting the lock before the upconvert has fully completed.
          * Do not prevent the dc thread from downconverting if NONBLOCK lock
          * had already returned.
          */
         if (!(lockres->l_flags & OCFS2_LOCK_NONBLOCK_FINISHED))
                 lockres_or_flags(lockres, OCFS2_LOCK_UPCONVERT_FINISHING);
         else
                 lockres_clear_flags(lockres, OCFS2_LOCK_NONBLOCK_FINISHED);
 
         lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
 }
 
 static inline void ocfs2_generic_handle_attach_action(struct ocfs2_lock_res *lockres)
 {
         BUG_ON((!(lockres->l_flags & OCFS2_LOCK_BUSY)));
         BUG_ON(lockres->l_flags & OCFS2_LOCK_ATTACHED);
 
         if (lockres->l_requested > DLM_LOCK_NL &&
             !(lockres->l_flags & OCFS2_LOCK_LOCAL) &&
             lockres->l_ops->flags & LOCK_TYPE_REQUIRES_REFRESH)
                 lockres_or_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
 
         lockres->l_level = lockres->l_requested;
         lockres_or_flags(lockres, OCFS2_LOCK_ATTACHED);
         lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
 }
 
 static int ocfs2_generic_handle_bast(struct ocfs2_lock_res *lockres,
                                      int level)
 {
         int needs_downconvert = 0;
 
         assert_spin_locked(&lockres->l_lock);
 
         if (level > lockres->l_blocking) {
                 /* only schedule a downconvert if we haven't already scheduled
                  * one that goes low enough to satisfy the level we're
                  * blocking.  this also catches the case where we get
                  * duplicate BASTs */
                 if (ocfs2_highest_compat_lock_level(level) <
                     ocfs2_highest_compat_lock_level(lockres->l_blocking))
                         needs_downconvert = 1;
 
                 lockres->l_blocking = level;
         }
 
         mlog(ML_BASTS, "lockres %s, block %d, level %d, l_block %d, dwn %d\n",
              lockres->l_name, level, lockres->l_level, lockres->l_blocking,
              needs_downconvert);
 
         if (needs_downconvert)
                 lockres_or_flags(lockres, OCFS2_LOCK_BLOCKED);
         mlog(0, "needs_downconvert = %d\n", needs_downconvert);
         return needs_downconvert;
 }
 
 /*
  * OCFS2_LOCK_PENDING and l_pending_gen.
  *
  * Why does OCFS2_LOCK_PENDING exist?  To close a race between setting
  * OCFS2_LOCK_BUSY and calling ocfs2_dlm_lock().  See ocfs2_unblock_lock()
  * for more details on the race.
  *
  * OCFS2_LOCK_PENDING closes the race quite nicely.  However, it introduces
  * a race on itself.  In o2dlm, we can get the ast before ocfs2_dlm_lock()
  * returns.  The ast clears OCFS2_LOCK_BUSY, and must therefore clear
  * OCFS2_LOCK_PENDING at the same time.  When ocfs2_dlm_lock() returns,
  * the caller is going to try to clear PENDING again.  If nothing else is
  * happening, __lockres_clear_pending() sees PENDING is unset and does
  * nothing.
  *
  * But what if another path (eg downconvert thread) has just started a
  * new locking action?  The other path has re-set PENDING.  Our path
  * cannot clear PENDING, because that will re-open the original race
  * window.
  *
  * [Example]
  *
  * ocfs2_meta_lock()
  *  ocfs2_cluster_lock()
  *   set BUSY
  *   set PENDING
  *   drop l_lock
  *   ocfs2_dlm_lock()
  *    ocfs2_locking_ast()               ocfs2_downconvert_thread()
  *     clear PENDING                     ocfs2_unblock_lock()
  *                                        take_l_lock
  *                                        !BUSY
  *                                        ocfs2_prepare_downconvert()
  *                                         set BUSY
  *                                         set PENDING
  *                                        drop l_lock
  *   take l_lock
  *   clear PENDING
  *   drop l_lock
  *                      <window>
  *                                        ocfs2_dlm_lock()
  *
  * So as you can see, we now have a window where l_lock is not held,
  * PENDING is not set, and ocfs2_dlm_lock() has not been called.
  *
  * The core problem is that ocfs2_cluster_lock() has cleared the PENDING
  * set by ocfs2_prepare_downconvert().  That wasn't nice.
  *
  * To solve this we introduce l_pending_gen.  A call to
  * lockres_clear_pending() will only do so when it is passed a generation
  * number that matches the lockres.  lockres_set_pending() will return the
  * current generation number.  When ocfs2_cluster_lock() goes to clear
  * PENDING, it passes the generation it got from set_pending().  In our
  * example above, the generation numbers will *not* match.  Thus,
  * ocfs2_cluster_lock() will not clear the PENDING set by
  * ocfs2_prepare_downconvert().
  */
 
 /* Unlocked version for ocfs2_locking_ast() */
 static void __lockres_clear_pending(struct ocfs2_lock_res *lockres,
                                     unsigned int generation,
                                     struct ocfs2_super *osb)
 {
         assert_spin_locked(&lockres->l_lock);
 
         /*
          * The ast and locking functions can race us here.  The winner
          * will clear pending, the loser will not.
          */
         if (!(lockres->l_flags & OCFS2_LOCK_PENDING) ||
             (lockres->l_pending_gen != generation))
                 return;
 
         lockres_clear_flags(lockres, OCFS2_LOCK_PENDING);
         lockres->l_pending_gen++;
 
         /*
          * The downconvert thread may have skipped us because we
          * were PENDING.  Wake it up.
          */
         if (lockres->l_flags & OCFS2_LOCK_BLOCKED)
                 ocfs2_wake_downconvert_thread(osb);
 }
 
 /* Locked version for callers of ocfs2_dlm_lock() */
 static void lockres_clear_pending(struct ocfs2_lock_res *lockres,
                                   unsigned int generation,
                                   struct ocfs2_super *osb)
 {
         unsigned long flags;
 
         spin_lock_irqsave(&lockres->l_lock, flags);
         __lockres_clear_pending(lockres, generation, osb);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 }
 
 static unsigned int lockres_set_pending(struct ocfs2_lock_res *lockres)
 {
         assert_spin_locked(&lockres->l_lock);
         BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BUSY));
 
         lockres_or_flags(lockres, OCFS2_LOCK_PENDING);
 
         return lockres->l_pending_gen;
 }
 
 static void ocfs2_blocking_ast(struct ocfs2_dlm_lksb *lksb, int level)
 {
         struct ocfs2_lock_res *lockres = ocfs2_lksb_to_lock_res(lksb);
         struct ocfs2_super *osb = ocfs2_get_lockres_osb(lockres);
         int needs_downconvert;
         unsigned long flags;
 
         BUG_ON(level <= DLM_LOCK_NL);
 
         mlog(ML_BASTS, "BAST fired for lockres %s, blocking %d, level %d, "
              "type %s\n", lockres->l_name, level, lockres->l_level,
              ocfs2_lock_type_string(lockres->l_type));
 
         /*
          * We can skip the bast for locks which don't enable caching -
          * they'll be dropped at the earliest possible time anyway.
          */
         if (lockres->l_flags & OCFS2_LOCK_NOCACHE)
                 return;
 
         spin_lock_irqsave(&lockres->l_lock, flags);
         needs_downconvert = ocfs2_generic_handle_bast(lockres, level);
         if (needs_downconvert)
                 ocfs2_schedule_blocked_lock(osb, lockres);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
         wake_up(&lockres->l_event);
 
         ocfs2_wake_downconvert_thread(osb);
 }
 
 static void ocfs2_locking_ast(struct ocfs2_dlm_lksb *lksb)
 {
         struct ocfs2_lock_res *lockres = ocfs2_lksb_to_lock_res(lksb);
         struct ocfs2_super *osb = ocfs2_get_lockres_osb(lockres);
         unsigned long flags;
         int status;
 
         spin_lock_irqsave(&lockres->l_lock, flags);
 
         status = ocfs2_dlm_lock_status(&lockres->l_lksb);
 
         if (status == -EAGAIN) {
                 lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
                 goto out;
         }
 
         if (status) {
                 mlog(ML_ERROR, "lockres %s: lksb status value of %d!\n",
                      lockres->l_name, status);
                 spin_unlock_irqrestore(&lockres->l_lock, flags);
                 return;
         }
 
         mlog(ML_BASTS, "AST fired for lockres %s, action %d, unlock %d, "
              "level %d => %d\n", lockres->l_name, lockres->l_action,
              lockres->l_unlock_action, lockres->l_level, lockres->l_requested);
 
         switch(lockres->l_action) {
         case OCFS2_AST_ATTACH:
                 ocfs2_generic_handle_attach_action(lockres);
                 lockres_clear_flags(lockres, OCFS2_LOCK_LOCAL);
                 break;
         case OCFS2_AST_CONVERT:
                 ocfs2_generic_handle_convert_action(lockres);
                 break;
         case OCFS2_AST_DOWNCONVERT:
                 ocfs2_generic_handle_downconvert_action(lockres);
                 break;
         default:
                 mlog(ML_ERROR, "lockres %s: AST fired with invalid action: %u, "
                      "flags 0x%lx, unlock: %u\n",
                      lockres->l_name, lockres->l_action, lockres->l_flags,
                      lockres->l_unlock_action);
                 BUG();
         }
 out:
         /* set it to something invalid so if we get called again we
          * can catch it. */
         lockres->l_action = OCFS2_AST_INVALID;
 
         /* Did we try to cancel this lock?  Clear that state */
         if (lockres->l_unlock_action == OCFS2_UNLOCK_CANCEL_CONVERT)
                 lockres->l_unlock_action = OCFS2_UNLOCK_INVALID;
 
         /*
          * We may have beaten the locking functions here.  We certainly
          * know that dlm_lock() has been called :-)
          * Because we can't have two lock calls in flight at once, we
          * can use lockres->l_pending_gen.
          */
         __lockres_clear_pending(lockres, lockres->l_pending_gen,  osb);
 
         wake_up(&lockres->l_event);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 }
 
 static void ocfs2_unlock_ast(struct ocfs2_dlm_lksb *lksb, int error)
 {
         struct ocfs2_lock_res *lockres = ocfs2_lksb_to_lock_res(lksb);
         unsigned long flags;
 
         mlog(ML_BASTS, "UNLOCK AST fired for lockres %s, action = %d\n",
              lockres->l_name, lockres->l_unlock_action);
 
         spin_lock_irqsave(&lockres->l_lock, flags);
         if (error) {
                 mlog(ML_ERROR, "Dlm passes error %d for lock %s, "
                      "unlock_action %d\n", error, lockres->l_name,
                      lockres->l_unlock_action);
                 spin_unlock_irqrestore(&lockres->l_lock, flags);
                 return;
         }
 
         switch(lockres->l_unlock_action) {
         case OCFS2_UNLOCK_CANCEL_CONVERT:
                 mlog(0, "Cancel convert success for %s\n", lockres->l_name);
                 lockres->l_action = OCFS2_AST_INVALID;
                 /* Downconvert thread may have requeued this lock, we
                  * need to wake it. */
                 if (lockres->l_flags & OCFS2_LOCK_BLOCKED)
                         ocfs2_wake_downconvert_thread(ocfs2_get_lockres_osb(lockres));
                 break;
         case OCFS2_UNLOCK_DROP_LOCK:
                 lockres->l_level = DLM_LOCK_IV;
                 break;
         default:
                 BUG();
         }
 
         lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
         lockres->l_unlock_action = OCFS2_UNLOCK_INVALID;
         wake_up(&lockres->l_event);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 }
 
 /*
  * This is the filesystem locking protocol.  It provides the lock handling
  * hooks for the underlying DLM.  It has a maximum version number.
  * The version number allows interoperability with systems running at
  * the same major number and an equal or smaller minor number.
  *
  * Whenever the filesystem does new things with locks (adds or removes a
  * lock, orders them differently, does different things underneath a lock),
  * the version must be changed.  The protocol is negotiated when joining
  * the dlm domain.  A node may join the domain if its major version is
  * identical to all other nodes and its minor version is greater than
  * or equal to all other nodes.  When its minor version is greater than
  * the other nodes, it will run at the minor version specified by the
  * other nodes.
  *
  * If a locking change is made that will not be compatible with older
  * versions, the major number must be increased and the minor version set
  * to zero.  If a change merely adds a behavior that can be disabled when
  * speaking to older versions, the minor version must be increased.  If a
  * change adds a fully backwards compatible change (eg, LVB changes that
  * are just ignored by older versions), the version does not need to be
  * updated.
  */
 static struct ocfs2_locking_protocol lproto = {
         .lp_max_version = {
                 .pv_major = OCFS2_LOCKING_PROTOCOL_MAJOR,
                 .pv_minor = OCFS2_LOCKING_PROTOCOL_MINOR,
         },
         .lp_lock_ast            = ocfs2_locking_ast,
         .lp_blocking_ast        = ocfs2_blocking_ast,
         .lp_unlock_ast          = ocfs2_unlock_ast,
 };
 
 void ocfs2_set_locking_protocol(void)
 {
         ocfs2_stack_glue_set_max_proto_version(&lproto.lp_max_version);
 }
 
 static inline void ocfs2_recover_from_dlm_error(struct ocfs2_lock_res *lockres,
                                                 int convert)
 {
         unsigned long flags;
 
         spin_lock_irqsave(&lockres->l_lock, flags);
         lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
         lockres_clear_flags(lockres, OCFS2_LOCK_UPCONVERT_FINISHING);
         if (convert)
                 lockres->l_action = OCFS2_AST_INVALID;
         else
                 lockres->l_unlock_action = OCFS2_UNLOCK_INVALID;
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
         wake_up(&lockres->l_event);
 }
 
 /* Note: If we detect another process working on the lock (i.e.,
  * OCFS2_LOCK_BUSY), we'll bail out returning 0. It's up to the caller
  * to do the right thing in that case.
  */
 static int ocfs2_lock_create(struct ocfs2_super *osb,
                              struct ocfs2_lock_res *lockres,
                              int level,
                              u32 dlm_flags)
 {
         int ret = 0;
         unsigned long flags;
         unsigned int gen;
 
         mlog(0, "lock %s, level = %d, flags = %u\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);
         gen = lockres_set_pending(lockres);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
         ret = ocfs2_dlm_lock(osb->cconn,
                              level,
                              &lockres->l_lksb,
                              dlm_flags,
                              lockres->l_name,
                              OCFS2_LOCK_ID_MAX_LEN - 1);
         lockres_clear_pending(lockres, gen, osb);
         if (ret) {
                 ocfs2_log_dlm_error("ocfs2_dlm_lock", ret, lockres);
                 ocfs2_recover_from_dlm_error(lockres, 1);
         }
 
         mlog(0, "lock %s, return from ocfs2_dlm_lock\n", lockres->l_name);
 
 bail:
         return ret;
 }
 
 static inline int ocfs2_check_wait_flag(struct ocfs2_lock_res *lockres,
                                         int flag)
 {
         unsigned long flags;
         int ret;
 
         spin_lock_irqsave(&lockres->l_lock, flags);
         ret = lockres->l_flags & flag;
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
         return ret;
 }
 
 static inline void ocfs2_wait_on_busy_lock(struct ocfs2_lock_res *lockres)
 
 {
         wait_event(lockres->l_event,
                    !ocfs2_check_wait_flag(lockres, OCFS2_LOCK_BUSY));
 }
 
 static inline void ocfs2_wait_on_refreshing_lock(struct ocfs2_lock_res *lockres)
 
 {
         wait_event(lockres->l_event,
                    !ocfs2_check_wait_flag(lockres, OCFS2_LOCK_REFRESHING));
 }
 
 /* predict what lock level we'll be dropping down to on behalf
  * of another node, and return true if the currently wanted
  * level will be compatible with it. */
 static inline int ocfs2_may_continue_on_blocked_lock(struct ocfs2_lock_res *lockres,
                                                      int wanted)
 {
         BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BLOCKED));
 
         return wanted <= ocfs2_highest_compat_lock_level(lockres->l_blocking);
 }
 
 static void ocfs2_init_mask_waiter(struct ocfs2_mask_waiter *mw)
 {
         INIT_LIST_HEAD(&mw->mw_item);
         init_completion(&mw->mw_complete);
         ocfs2_init_start_time(mw);
 }
 
 static int ocfs2_wait_for_mask(struct ocfs2_mask_waiter *mw)
 {
         wait_for_completion(&mw->mw_complete);
         /* Re-arm the completion in case we want to wait on it again */
         reinit_completion(&mw->mw_complete);
         return mw->mw_status;
 }
 
 static void lockres_add_mask_waiter(struct ocfs2_lock_res *lockres,
                                     struct ocfs2_mask_waiter *mw,
                                     unsigned long mask,
                                     unsigned long goal)
 {
         BUG_ON(!list_empty(&mw->mw_item));
 
         assert_spin_locked(&lockres->l_lock);
 
         list_add_tail(&mw->mw_item, &lockres->l_mask_waiters);
         mw->mw_mask = mask;
         mw->mw_goal = goal;
         ocfs2_track_lock_wait(lockres);
 }
 
 /* returns 0 if the mw that was removed was already satisfied, -EBUSY
  * if the mask still hadn't reached its goal */
 static int __lockres_remove_mask_waiter(struct ocfs2_lock_res *lockres,
                                       struct ocfs2_mask_waiter *mw)
 {
         int ret = 0;
 
         assert_spin_locked(&lockres->l_lock);
         if (!list_empty(&mw->mw_item)) {
                 if ((lockres->l_flags & mw->mw_mask) != mw->mw_goal)
                         ret = -EBUSY;
 
                 list_del_init(&mw->mw_item);
                 init_completion(&mw->mw_complete);
                 ocfs2_track_lock_wait(lockres);
         }
 
         return ret;
 }
 
 static int lockres_remove_mask_waiter(struct ocfs2_lock_res *lockres,
                                       struct ocfs2_mask_waiter *mw)
 {
         unsigned long flags;
         int ret = 0;
 
         spin_lock_irqsave(&lockres->l_lock, flags);
         ret = __lockres_remove_mask_waiter(lockres, mw);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
         return ret;
 
 }
 
 static int ocfs2_wait_for_mask_interruptible(struct ocfs2_mask_waiter *mw,
                                              struct ocfs2_lock_res *lockres)
 {
         int ret;
 
         ret = wait_for_completion_interruptible(&mw->mw_complete);
         if (ret)
                 lockres_remove_mask_waiter(lockres, mw);
         else
                 ret = mw->mw_status;
         /* Re-arm the completion in case we want to wait on it again */
         reinit_completion(&mw->mw_complete);
         return ret;
 }
 
 static int __ocfs2_cluster_lock(struct ocfs2_super *osb,
                                 struct ocfs2_lock_res *lockres,
                                 int level,
                                 u32 lkm_flags,
                                 int arg_flags,
                                 int l_subclass,
                                 unsigned long caller_ip)
 {
         struct ocfs2_mask_waiter mw;
         int wait, catch_signals = !(osb->s_mount_opt & OCFS2_MOUNT_NOINTR);
         int ret = 0; /* gcc doesn't realize wait = 1 guarantees ret is set */
         unsigned long flags;
         unsigned int gen;
         int noqueue_attempted = 0;
         int dlm_locked = 0;
         int kick_dc = 0;
 
         if (!(lockres->l_flags & OCFS2_LOCK_INITIALIZED)) {
                 mlog_errno(-EINVAL);
                 return -EINVAL;
         }
 
         ocfs2_init_mask_waiter(&mw);
 
         if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB)
                 lkm_flags |= DLM_LKF_VALBLK;
 
 again:
         wait = 0;
 
         spin_lock_irqsave(&lockres->l_lock, flags);
 
         if (catch_signals && signal_pending(current)) {
                 ret = -ERESTARTSYS;
                 goto unlock;
         }
 
         mlog_bug_on_msg(lockres->l_flags & OCFS2_LOCK_FREEING,
                         "Cluster lock called on freeing lockres %s! flags "
                         "0x%lx\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_UPCONVERT_FINISHING) {
                 /*
                  * We've upconverted. If the lock now has a level we can
                  * work with, we take it. If, however, the lock is not at the
                  * required level, we go thru the full cycle. One way this could
                  * happen is if a process requesting an upconvert to PR is
                  * closely followed by another requesting upconvert to an EX.
                  * If the process requesting EX lands here, we want it to
                  * continue attempting to upconvert and let the process
                  * requesting PR take the lock.
                  * If multiple processes request upconvert to PR, the first one
                  * here will take the lock. The others will have to go thru the
                  * OCFS2_LOCK_BLOCKED check to ensure that there is no pending
                  * downconvert request.
                  */
                 if (level <= lockres->l_level)
                         goto update_holders;
         }
 
         if (lockres->l_flags & OCFS2_LOCK_BLOCKED &&
             !ocfs2_may_continue_on_blocked_lock(lockres, level)) {
                 /* is the lock is currently blocked on behalf of
                  * another node */
                 lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BLOCKED, 0);
                 wait = 1;
                 goto unlock;
         }
 
         if (level > lockres->l_level) {
                 if (noqueue_attempted > 0) {
                         ret = -EAGAIN;
                         goto unlock;
                 }
                 if (lkm_flags & DLM_LKF_NOQUEUE)
                         noqueue_attempted = 1;
 
                 if (lockres->l_action != OCFS2_AST_INVALID)
                         mlog(ML_ERROR, "lockres %s has action %u pending\n",
                              lockres->l_name, lockres->l_action);
 
                 if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED)) {
                         lockres->l_action = OCFS2_AST_ATTACH;
                         lkm_flags &= ~DLM_LKF_CONVERT;
                 } else {
                         lockres->l_action = OCFS2_AST_CONVERT;
                         lkm_flags |= DLM_LKF_CONVERT;
                 }
 
                 lockres->l_requested = level;
                 lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
                 gen = lockres_set_pending(lockres);
                 spin_unlock_irqrestore(&lockres->l_lock, flags);
 
                 BUG_ON(level == DLM_LOCK_IV);
                 BUG_ON(level == DLM_LOCK_NL);
 
                 mlog(ML_BASTS, "lockres %s, convert from %d to %d\n",
                      lockres->l_name, lockres->l_level, level);
 
                 /* call dlm_lock to upgrade lock now */
                 ret = ocfs2_dlm_lock(osb->cconn,
                                      level,
                                      &lockres->l_lksb,
                                      lkm_flags,
                                      lockres->l_name,
                                      OCFS2_LOCK_ID_MAX_LEN - 1);
                 lockres_clear_pending(lockres, gen, osb);
                 if (ret) {
                         if (!(lkm_flags & DLM_LKF_NOQUEUE) ||
                             (ret != -EAGAIN)) {
                                 ocfs2_log_dlm_error("ocfs2_dlm_lock",
                                                     ret, lockres);
                         }
                         ocfs2_recover_from_dlm_error(lockres, 1);
                         goto out;
                 }
                 dlm_locked = 1;
 
                 mlog(0, "lock %s, successful return from ocfs2_dlm_lock\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;
         }
 
 update_holders:
         /* Ok, if we get here then we're good to go. */
         ocfs2_inc_holders(lockres, level);
 
         ret = 0;
 unlock:
         lockres_clear_flags(lockres, OCFS2_LOCK_UPCONVERT_FINISHING);
 
         /* ocfs2_unblock_lock request on seeing OCFS2_LOCK_UPCONVERT_FINISHING */
         kick_dc = (lockres->l_flags & OCFS2_LOCK_BLOCKED);
 
         spin_unlock_irqrestore(&lockres->l_lock, flags);
         if (kick_dc)
                 ocfs2_wake_downconvert_thread(osb);
 out:
         /*
          * This is helping work around a lock inversion between the page lock
          * and dlm locks.  One path holds the page lock while calling aops
          * which block acquiring dlm locks.  The voting thread holds dlm
          * locks while acquiring page locks while down converting data locks.
          * This block is helping an aop path notice the inversion and back
          * off to unlock its page lock before trying the dlm lock again.
          */
         if (wait && arg_flags & OCFS2_LOCK_NONBLOCK &&
             mw.mw_mask & (OCFS2_LOCK_BUSY|OCFS2_LOCK_BLOCKED)) {
                 wait = 0;
                 spin_lock_irqsave(&lockres->l_lock, flags);
                 if (__lockres_remove_mask_waiter(lockres, &mw)) {
                         if (dlm_locked)
                                 lockres_or_flags(lockres,
                                         OCFS2_LOCK_NONBLOCK_FINISHED);
                         spin_unlock_irqrestore(&lockres->l_lock, flags);
                         ret = -EAGAIN;
                 } else {
                         spin_unlock_irqrestore(&lockres->l_lock, flags);
                         goto again;
                 }
         }
         if (wait) {
                 ret = ocfs2_wait_for_mask(&mw);
                 if (ret == 0)
                         goto again;
                 mlog_errno(ret);
         }
         ocfs2_update_lock_stats(lockres, level, &mw, ret);
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
         if (!ret && lockres->l_lockdep_map.key != NULL) {
                 if (level == DLM_LOCK_PR)
                         rwsem_acquire_read(&lockres->l_lockdep_map, l_subclass,
                                 !!(arg_flags & OCFS2_META_LOCK_NOQUEUE),
                                 caller_ip);
                 else
                         rwsem_acquire(&lockres->l_lockdep_map, l_subclass,
                                 !!(arg_flags & OCFS2_META_LOCK_NOQUEUE),
                                 caller_ip);
         }
 #endif
         return ret;
 }
 
 static inline int ocfs2_cluster_lock(struct ocfs2_super *osb,
                                      struct ocfs2_lock_res *lockres,
                                      int level,
                                      u32 lkm_flags,
                                      int arg_flags)
 {
         return __ocfs2_cluster_lock(osb, lockres, level, lkm_flags, arg_flags,
                                     0, _RET_IP_);
 }
 
 
 static void __ocfs2_cluster_unlock(struct ocfs2_super *osb,
                                    struct ocfs2_lock_res *lockres,
                                    int level,
                                    unsigned long caller_ip)
 {
         unsigned long flags;
 
         spin_lock_irqsave(&lockres->l_lock, flags);
         ocfs2_dec_holders(lockres, level);
         ocfs2_downconvert_on_unlock(osb, lockres);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
         if (lockres->l_lockdep_map.key != NULL)
                 rwsem_release(&lockres->l_lockdep_map, caller_ip);
 #endif
 }
 
 static int ocfs2_create_new_lock(struct ocfs2_super *osb,
                                  struct ocfs2_lock_res *lockres,
                                  int ex,
                                  int local)
 {
         int level =  ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         unsigned long flags;
         u32 lkm_flags = local ? DLM_LKF_LOCAL : 0;
 
         spin_lock_irqsave(&lockres->l_lock, flags);
         BUG_ON(lockres->l_flags & OCFS2_LOCK_ATTACHED);
         lockres_or_flags(lockres, OCFS2_LOCK_LOCAL);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
         return ocfs2_lock_create(osb, lockres, level, lkm_flags);
 }
 
 /* Grants us an EX lock on the data and metadata resources, skipping
  * the normal cluster directory lookup. Use this ONLY on newly created
  * inodes which other nodes can't possibly see, and which haven't been
  * hashed in the inode hash yet. This can give us a good performance
  * increase as it'll skip the network broadcast normally associated
  * with creating a new lock resource. */
 int ocfs2_create_new_inode_locks(struct inode *inode)
 {
         int ret;
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
         BUG_ON(!ocfs2_inode_is_new(inode));
 
         mlog(0, "Inode %llu\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 DLM_LKF_LOCAL on a meta data lock as they
          * don't use a generation in their lock names.
          */
         ret = ocfs2_create_new_lock(osb, &OCFS2_I(inode)->ip_inode_lockres, 1, 0);
         if (ret) {
                 mlog_errno(ret);
                 goto bail;
         }
 
         ret = ocfs2_create_new_lock(osb, &OCFS2_I(inode)->ip_open_lockres, 0, 0);
         if (ret)
                 mlog_errno(ret);
 
 bail:
         return ret;
 }
 
 int ocfs2_rw_lock(struct inode *inode, int write)
 {
         int status, level;
         struct ocfs2_lock_res *lockres;
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
         mlog(0, "inode %llu take %s RW lock\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 ? DLM_LOCK_EX : DLM_LOCK_PR;
 
         status = ocfs2_cluster_lock(osb, lockres, level, 0, 0);
         if (status < 0)
                 mlog_errno(status);
 
         return status;
 }
 
 int ocfs2_try_rw_lock(struct inode *inode, int write)
 {
         int status, level;
         struct ocfs2_lock_res *lockres;
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
         mlog(0, "inode %llu try to 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 ? DLM_LOCK_EX : DLM_LOCK_PR;
 
         status = ocfs2_cluster_lock(osb, lockres, level, DLM_LKF_NOQUEUE, 0);
         return status;
 }
 
 void ocfs2_rw_unlock(struct inode *inode, int write)
 {
         int level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
         struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_rw_lockres;
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
         mlog(0, "inode %llu drop %s RW lock\n",
              (unsigned long long)OCFS2_I(inode)->ip_blkno,
              write ? "EXMODE" : "PRMODE");
 
         if (!ocfs2_mount_local(osb))
                 ocfs2_cluster_unlock(osb, lockres, level);
 }
 
 /*
  * ocfs2_open_lock always get PR mode lock.
  */
 int ocfs2_open_lock(struct inode *inode)
 {
         int status = 0;
         struct ocfs2_lock_res *lockres;
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
         mlog(0, "inode %llu take PRMODE open lock\n",
              (unsigned long long)OCFS2_I(inode)->ip_blkno);
 
         if (ocfs2_is_hard_readonly(osb) || ocfs2_mount_local(osb))
                 goto out;
 
         lockres = &OCFS2_I(inode)->ip_open_lockres;
 
         status = ocfs2_cluster_lock(osb, lockres, DLM_LOCK_PR, 0, 0);
         if (status < 0)
                 mlog_errno(status);
 
 out:
         return status;
 }
 
 int ocfs2_try_open_lock(struct inode *inode, int write)
 {
         int status = 0, level;
         struct ocfs2_lock_res *lockres;
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
         mlog(0, "inode %llu try to take %s open lock\n",
              (unsigned long long)OCFS2_I(inode)->ip_blkno,
              write ? "EXMODE" : "PRMODE");
 
         if (ocfs2_is_hard_readonly(osb)) {
                 if (write)
                         status = -EROFS;
                 goto out;
         }
 
         if (ocfs2_mount_local(osb))
                 goto out;
 
         lockres = &OCFS2_I(inode)->ip_open_lockres;
 
         level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
 
         /*
          * The file system may already holding a PRMODE/EXMODE open lock.
          * Since we pass DLM_LKF_NOQUEUE, the request won't block waiting on
          * other nodes and the -EAGAIN will indicate to the caller that
          * this inode is still in use.
          */
         status = ocfs2_cluster_lock(osb, lockres, level, DLM_LKF_NOQUEUE, 0);
 
 out:
         return status;
 }
 
 /*
  * ocfs2_open_unlock unlock PR and EX mode open locks.
  */
 void ocfs2_open_unlock(struct inode *inode)
 {
         struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_open_lockres;
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
         mlog(0, "inode %llu drop open lock\n",
              (unsigned long long)OCFS2_I(inode)->ip_blkno);
 
         if (ocfs2_mount_local(osb))
                 goto out;
 
         if(lockres->l_ro_holders)
                 ocfs2_cluster_unlock(osb, lockres, DLM_LOCK_PR);
         if(lockres->l_ex_holders)
                 ocfs2_cluster_unlock(osb, lockres, DLM_LOCK_EX);
 
 out:
         return;
 }
 
 static int ocfs2_flock_handle_signal(struct ocfs2_lock_res *lockres,
                                      int level)
 {
         int ret;
         struct ocfs2_super *osb = ocfs2_get_lockres_osb(lockres);
         unsigned long flags;
         struct ocfs2_mask_waiter mw;
 
         ocfs2_init_mask_waiter(&mw);
 
 retry_cancel:
         spin_lock_irqsave(&lockres->l_lock, flags);
         if (lockres->l_flags & OCFS2_LOCK_BUSY) {
                 ret = ocfs2_prepare_cancel_convert(osb, lockres);
                 if (ret) {
                         spin_unlock_irqrestore(&lockres->l_lock, flags);
                         ret = ocfs2_cancel_convert(osb, lockres);
                         if (ret < 0) {
                                 mlog_errno(ret);
                                 goto out;
                         }
                         goto retry_cancel;
                 }
                 lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
                 spin_unlock_irqrestore(&lockres->l_lock, flags);
 
                 ocfs2_wait_for_mask(&mw);
                 goto retry_cancel;
         }
 
         ret = -ERESTARTSYS;
         /*
          * We may still have gotten the lock, in which case there's no
          * point to restarting the syscall.
          */
         if (lockres->l_level == level)
                 ret = 0;
 
         mlog(0, "Cancel returning %d. flags: 0x%lx, level: %d, act: %d\n", ret,
              lockres->l_flags, lockres->l_level, lockres->l_action);
 
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
 out:
         return ret;
 }
 
 /*
  * ocfs2_file_lock() and ocfs2_file_unlock() map to a single pair of
  * flock() calls. The locking approach this requires is sufficiently
  * different from all other cluster lock types that we implement a
  * separate path to the "low-level" dlm calls. In particular:
  *
  * - No optimization of lock levels is done - we take at exactly
  *   what's been requested.
  *
  * - No lock caching is employed. We immediately downconvert to
  *   no-lock at unlock time. This also means flock locks never go on
  *   the blocking list).
  *
  * - Since userspace can trivially deadlock itself with flock, we make
  *   sure to allow cancellation of a misbehaving applications flock()
  *   request.
  *
  * - Access to any flock lockres doesn't require concurrency, so we
  *   can simplify the code by requiring the caller to guarantee
  *   serialization of dlmglue flock calls.
  */
 int ocfs2_file_lock(struct file *file, int ex, int trylock)
 {
         int ret, level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         unsigned int lkm_flags = trylock ? DLM_LKF_NOQUEUE : 0;
         unsigned long flags;
         struct ocfs2_file_private *fp = file->private_data;
         struct ocfs2_lock_res *lockres = &fp->fp_flock;
         struct ocfs2_super *osb = OCFS2_SB(file->f_mapping->host->i_sb);
         struct ocfs2_mask_waiter mw;
 
         ocfs2_init_mask_waiter(&mw);
 
         if ((lockres->l_flags & OCFS2_LOCK_BUSY) ||
             (lockres->l_level > DLM_LOCK_NL)) {
                 mlog(ML_ERROR,
                      "File lock \"%s\" has busy or locked state: flags: 0x%lx, "
                      "level: %u\n", lockres->l_name, lockres->l_flags,
                      lockres->l_level);
                 return -EINVAL;
         }
 
         spin_lock_irqsave(&lockres->l_lock, flags);
         if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED)) {
                 lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
                 spin_unlock_irqrestore(&lockres->l_lock, flags);
 
                 /*
                  * Get the lock at NLMODE to start - that way we
                  * can cancel the upconvert request if need be.
                  */
                 ret = ocfs2_lock_create(osb, lockres, DLM_LOCK_NL, 0);
                 if (ret < 0) {
                         mlog_errno(ret);
                         goto out;
                 }
 
                 ret = ocfs2_wait_for_mask(&mw);
                 if (ret) {
                         mlog_errno(ret);
                         goto out;
                 }
                 spin_lock_irqsave(&lockres->l_lock, flags);
         }
 
         lockres->l_action = OCFS2_AST_CONVERT;
         lkm_flags |= DLM_LKF_CONVERT;
         lockres->l_requested = level;
         lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
 
         lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
         ret = ocfs2_dlm_lock(osb->cconn, level, &lockres->l_lksb, lkm_flags,
                              lockres->l_name, OCFS2_LOCK_ID_MAX_LEN - 1);
         if (ret) {
                 if (!trylock || (ret != -EAGAIN)) {
                         ocfs2_log_dlm_error("ocfs2_dlm_lock", ret, lockres);
                         ret = -EINVAL;
                 }
 
                 ocfs2_recover_from_dlm_error(lockres, 1);
                 lockres_remove_mask_waiter(lockres, &mw);
                 goto out;
         }
 
         ret = ocfs2_wait_for_mask_interruptible(&mw, lockres);
         if (ret == -ERESTARTSYS) {
                 /*
                  * Userspace can cause deadlock itself with
                  * flock(). Current behavior locally is to allow the
                  * deadlock, but abort the system call if a signal is
                  * received. We follow this example, otherwise a
                  * poorly written program could sit in kernel until
                  * reboot.
                  *
                  * Handling this is a bit more complicated for Ocfs2
                  * though. We can't exit this function with an
                  * outstanding lock request, so a cancel convert is
                  * required. We intentionally overwrite 'ret' - if the
                  * cancel fails and the lock was granted, it's easier
                  * to just bubble success back up to the user.
                  */
                 ret = ocfs2_flock_handle_signal(lockres, level);
         } else if (!ret && (level > lockres->l_level)) {
                 /* Trylock failed asynchronously */
                 BUG_ON(!trylock);
                 ret = -EAGAIN;
         }
 
 out:
 
         mlog(0, "Lock: \"%s\" ex: %d, trylock: %d, returns: %d\n",
              lockres->l_name, ex, trylock, ret);
         return ret;
 }
 
 void ocfs2_file_unlock(struct file *file)
 {
         int ret;
         unsigned int gen;
         unsigned long flags;
         struct ocfs2_file_private *fp = file->private_data;
         struct ocfs2_lock_res *lockres = &fp->fp_flock;
         struct ocfs2_super *osb = OCFS2_SB(file->f_mapping->host->i_sb);
         struct ocfs2_mask_waiter mw;
 
         ocfs2_init_mask_waiter(&mw);
 
         if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED))
                 return;
 
         if (lockres->l_level == DLM_LOCK_NL)
                 return;
 
         mlog(0, "Unlock: \"%s\" flags: 0x%lx, level: %d, act: %d\n",
              lockres->l_name, lockres->l_flags, lockres->l_level,
              lockres->l_action);
 
         spin_lock_irqsave(&lockres->l_lock, flags);
         /*
          * Fake a blocking ast for the downconvert code.
          */
         lockres_or_flags(lockres, OCFS2_LOCK_BLOCKED);
         lockres->l_blocking = DLM_LOCK_EX;
 
         gen = ocfs2_prepare_downconvert(lockres, DLM_LOCK_NL);
         lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
         ret = ocfs2_downconvert_lock(osb, lockres, DLM_LOCK_NL, 0, gen);
         if (ret) {
                 mlog_errno(ret);
                 return;
         }
 
         ret = ocfs2_wait_for_mask(&mw);
         if (ret)
                 mlog_errno(ret);
 }
 
 static void ocfs2_downconvert_on_unlock(struct ocfs2_super *osb,
                                         struct ocfs2_lock_res *lockres)
 {
         int kick = 0;
 
         /* If we know that another node is waiting on our lock, kick
          * the downconvert thread * pre-emptively when we reach a release
          * condition. */
         if (lockres->l_flags & OCFS2_LOCK_BLOCKED) {
                 switch(lockres->l_blocking) {
                 case DLM_LOCK_EX:
                         if (!lockres->l_ex_holders && !lockres->l_ro_holders)
                                 kick = 1;
                         break;
                 case DLM_LOCK_PR:
                         if (!lockres->l_ex_holders)
                                 kick = 1;
                         break;
                 default:
                         BUG();
                 }
         }
 
         if (kick)
                 ocfs2_wake_downconvert_thread(osb);
 }
 
 #define OCFS2_SEC_BITS   34
 #define OCFS2_SEC_SHIFT  (64 - OCFS2_SEC_BITS)
 #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 timespec64 *spec)
 {
         u64 res;
         u64 sec = clamp_t(time64_t, spec->tv_sec, 0, 0x3ffffffffull);
         u32 nsec = spec->tv_nsec;
 
         res = (sec << OCFS2_SEC_SHIFT) | (nsec & OCFS2_NSEC_MASK);
 
         return res;
 }
 
 /* Call this with the lockres locked. I am reasonably sure we don't
  * need ip_lock in this function as anyone who would be changing those
  * values is supposed to be blocked in ocfs2_inode_lock right now. */
 static void __ocfs2_stuff_meta_lvb(struct inode *inode)
 {
         struct ocfs2_inode_info *oi = OCFS2_I(inode);
         struct ocfs2_lock_res *lockres = &oi->ip_inode_lockres;
         struct ocfs2_meta_lvb *lvb;
         struct timespec64 ts;
 
         lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
 
         /*
          * Invalidate the LVB of a deleted inode - this way other
          * nodes are forced to go to disk and discover the new inode
          * status.
          */
         if (oi->ip_flags & OCFS2_INODE_DELETED) {
                 lvb->lvb_version = 0;
                 goto out;
         }
 
         lvb->lvb_version   = OCFS2_LVB_VERSION;
         lvb->lvb_isize     = cpu_to_be64(i_size_read(inode));
         lvb->lvb_iclusters = cpu_to_be32(oi->ip_clusters);
         lvb->lvb_iuid      = cpu_to_be32(i_uid_read(inode));
         lvb->lvb_igid      = cpu_to_be32(i_gid_read(inode));
         lvb->lvb_imode     = cpu_to_be16(inode->i_mode);
         lvb->lvb_inlink    = cpu_to_be16(inode->i_nlink);
         ts = inode_get_atime(inode);
         lvb->lvb_iatime_packed = cpu_to_be64(ocfs2_pack_timespec(&ts));
         ts = inode_get_ctime(inode);
         lvb->lvb_ictime_packed = cpu_to_be64(ocfs2_pack_timespec(&ts));
         ts = inode_get_mtime(inode);
         lvb->lvb_imtime_packed = cpu_to_be64(ocfs2_pack_timespec(&ts));
         lvb->lvb_iattr    = cpu_to_be32(oi->ip_attr);
         lvb->lvb_idynfeatures = cpu_to_be16(oi->ip_dyn_features);
         lvb->lvb_igeneration = cpu_to_be32(inode->i_generation);
 
 out:
         mlog_meta_lvb(0, lockres);
 }
 
 static void ocfs2_unpack_timespec(struct timespec64 *spec,
                                   u64 packed_time)
 {
         spec->tv_sec = packed_time >> OCFS2_SEC_SHIFT;
         spec->tv_nsec = packed_time & OCFS2_NSEC_MASK;
 }
 
 static int ocfs2_refresh_inode_from_lvb(struct inode *inode)
 {
         struct ocfs2_inode_info *oi = OCFS2_I(inode);
         struct ocfs2_lock_res *lockres = &oi->ip_inode_lockres;
         struct ocfs2_meta_lvb *lvb;
         struct timespec64 ts;
 
         mlog_meta_lvb(0, lockres);
 
         lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
         if (inode_wrong_type(inode, be16_to_cpu(lvb->lvb_imode)))
                 return -ESTALE;
 
         /* We're safe here without the lockres lock... */
         spin_lock(&oi->ip_lock);
         oi->ip_clusters = be32_to_cpu(lvb->lvb_iclusters);
         i_size_write(inode, be64_to_cpu(lvb->lvb_isize));
 
         oi->ip_attr = be32_to_cpu(lvb->lvb_iattr);
         oi->ip_dyn_features = be16_to_cpu(lvb->lvb_idynfeatures);
         ocfs2_set_inode_flags(inode);
 
         /* fast-symlinks are a special case */
         if (S_ISLNK(inode->i_mode) && !oi->ip_clusters)
                 inode->i_blocks = 0;
         else
                 inode->i_blocks = ocfs2_inode_sector_count(inode);
 
         i_uid_write(inode, be32_to_cpu(lvb->lvb_iuid));
         i_gid_write(inode, be32_to_cpu(lvb->lvb_igid));
         inode->i_mode    = be16_to_cpu(lvb->lvb_imode);
         set_nlink(inode, be16_to_cpu(lvb->lvb_inlink));
         ocfs2_unpack_timespec(&ts, be64_to_cpu(lvb->lvb_iatime_packed));
         inode_set_atime_to_ts(inode, ts);
         ocfs2_unpack_timespec(&ts, be64_to_cpu(lvb->lvb_imtime_packed));
         inode_set_mtime_to_ts(inode, ts);
         ocfs2_unpack_timespec(&ts, be64_to_cpu(lvb->lvb_ictime_packed));
         inode_set_ctime_to_ts(inode, ts);
         spin_unlock(&oi->ip_lock);
         return 0;
 }
 
 static inline int ocfs2_meta_lvb_is_trustable(struct inode *inode,
                                               struct ocfs2_lock_res *lockres)
 {
         struct ocfs2_meta_lvb *lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
 
         if (ocfs2_dlm_lvb_valid(&lockres->l_lksb)
             && lvb->lvb_version == OCFS2_LVB_VERSION
             && be32_to_cpu(lvb->lvb_igeneration) == inode->i_generation)
                 return 1;
         return 0;
 }
 
 /* Determine whether a lock resource needs to be refreshed, and
  * arbitrate who gets to refresh it.
  *
  *   0 means no refresh needed.
  *
  *   > 0 means you need to refresh this and you MUST call
  *   ocfs2_complete_lock_res_refresh afterwards. */
 static int ocfs2_should_refresh_lock_res(struct ocfs2_lock_res *lockres)
 {
         unsigned long flags;
         int status = 0;
 
 refresh_check:
         spin_lock_irqsave(&lockres->l_lock, flags);
         if (!(lockres->l_flags & OCFS2_LOCK_NEEDS_REFRESH)) {
                 spin_unlock_irqrestore(&lockres->l_lock, flags);
                 goto bail;
         }
 
         if (lockres->l_flags & OCFS2_LOCK_REFRESHING) {
                 spin_unlock_irqrestore(&lockres->l_lock, flags);
 
                 ocfs2_wait_on_refreshing_lock(lockres);
                 goto refresh_check;
         }
 
         /* Ok, I'll be the one to refresh this lock. */
         lockres_or_flags(lockres, OCFS2_LOCK_REFRESHING);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
         status = 1;
 bail:
         mlog(0, "status %d\n", status);
         return status;
 }
 
 /* If status is non zero, I'll mark it as not being in refresh
  * anymroe, but i won't clear the needs refresh flag. */
 static inline void ocfs2_complete_lock_res_refresh(struct ocfs2_lock_res *lockres,
                                                    int status)
 {
         unsigned long flags;
 
         spin_lock_irqsave(&lockres->l_lock, flags);
         lockres_clear_flags(lockres, OCFS2_LOCK_REFRESHING);
         if (!status)
                 lockres_clear_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
         wake_up(&lockres->l_event);
 }
 
 /* may or may not return a bh if it went to disk. */
 static int ocfs2_inode_lock_update(struct inode *inode,
                                   struct buffer_head **bh)
 {
         int status = 0;
         struct ocfs2_inode_info *oi = OCFS2_I(inode);
         struct ocfs2_lock_res *lockres = &oi->ip_inode_lockres;
         struct ocfs2_dinode *fe;
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
         if (ocfs2_mount_local(osb))
                 goto bail;
 
         spin_lock(&oi->ip_lock);
         if (oi->ip_flags & OCFS2_INODE_DELETED) {
                 mlog(0, "Orphaned inode %llu was deleted while we "
                      "were waiting on a lock. ip_flags = 0x%x\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_CACHE(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);
                 status = ocfs2_refresh_inode_from_lvb(inode);
                 goto bail_refresh;
         } else {
                 /* Boo, we have to go to disk. */
                 /* read bh, cast, ocfs2_refresh_inode */
                 status = ocfs2_read_inode_block(inode, bh);
                 if (status < 0) {
                         mlog_errno(status);
                         goto bail_refresh;
                 }
                 fe = (struct ocfs2_dinode *) (*bh)->b_data;
                 if (inode_wrong_type(inode, le16_to_cpu(fe->i_mode))) {
                         status = -ESTALE;
                         goto bail_refresh;
                 }
 
                 /* This is a good chance to make sure we're not
                  * locking an invalid object.  ocfs2_read_inode_block()
                  * already checked that the inode block is sane.
                  *
                  * We bug on a stale inode here because we checked
                  * above whether it was wiped from disk. The wiping
                  * node provides a guarantee that we receive that
                  * message and can mark the inode before dropping any
                  * locks associated with it. */
                 mlog_bug_on_msg(inode->i_generation !=
                                 le32_to_cpu(fe->i_generation),
                                 "Invalid dinode %llu disk generation: %u "
                                 "inode->i_generation: %u\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);
                 ocfs2_track_lock_refresh(lockres);
         }
 
         status = 0;
 bail_refresh:
         ocfs2_complete_lock_res_refresh(lockres, status);
 bail:
         return status;
 }
 
 static int ocfs2_assign_bh(struct inode *inode,
                            struct buffer_head **ret_bh,
                            struct buffer_head *passed_bh)
 {
         int status;
 
         if (passed_bh) {
                 /* Ok, the update went to disk for us, use the
                  * returned bh. */
                 *ret_bh = passed_bh;
                 get_bh(*ret_bh);
 
                 return 0;
         }
 
         status = ocfs2_read_inode_block(inode, ret_bh);
         if (status < 0)
                 mlog_errno(status);
 
         return status;
 }
 
 /*
  * returns < 0 error if the callback will never be called, otherwise
  * the result of the lock will be communicated via the callback.
  */
 int ocfs2_inode_lock_full_nested(struct inode *inode,
                                  struct buffer_head **ret_bh,
                                  int ex,
                                  int arg_flags,
                                  int subclass)
 {
         int status, level, acquired;
         u32 dlm_flags;
         struct ocfs2_lock_res *lockres = NULL;
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
         struct buffer_head *local_bh = NULL;
 
         mlog(0, "inode %llu, take %s META lock\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 getbh;
         }
 
         if ((arg_flags & OCFS2_META_LOCK_GETBH) ||
             ocfs2_mount_local(osb))
                 goto update;
 
         if (!(arg_flags & OCFS2_META_LOCK_RECOVERY))
                 ocfs2_wait_for_recovery(osb);
 
         lockres = &OCFS2_I(inode)->ip_inode_lockres;
         level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         dlm_flags = 0;
         if (arg_flags & OCFS2_META_LOCK_NOQUEUE)
                 dlm_flags |= DLM_LKF_NOQUEUE;
 
         status = __ocfs2_cluster_lock(osb, lockres, level, dlm_flags,
                                       arg_flags, subclass, _RET_IP_);
         if (status < 0) {
                 if (status != -EAGAIN)
                         mlog_errno(status);
                 goto bail;
         }
 
         /* Notify the error cleanup path to drop the cluster lock. */
         acquired = 1;
 
         /* We wait twice because a node may have died while we were in
          * the lower dlm layers. The second time though, we've
          * committed to owning this lock so we don't allow signals to
          * abort the operation. */
         if (!(arg_flags & OCFS2_META_LOCK_RECOVERY))
                 ocfs2_wait_for_recovery(osb);
 
 update:
         /*
          * We only see this flag if we're being called from
          * ocfs2_read_locked_inode(). It means we're locking an inode
          * which hasn't been populated yet, so clear the refresh flag
          * and let the caller handle it.
          */
         if (inode->i_state & I_NEW) {
                 status = 0;
                 if (lockres)
                         ocfs2_complete_lock_res_refresh(lockres, 0);
                 goto bail;
         }
 
         /* This is fun. The caller may want a bh back, or it may
          * not. ocfs2_inode_lock_update definitely wants one in, but
          * may or may not read one, depending on what's in the
          * LVB. The result of all of this is that we've *only* gone to
          * disk if we have to, so the complexity is worthwhile. */
         status = ocfs2_inode_lock_update(inode, &local_bh);
         if (status < 0) {
                 if (status != -ENOENT)
                         mlog_errno(status);
                 goto bail;
         }
 getbh:
         if (ret_bh) {
                 status = ocfs2_assign_bh(inode, ret_bh, local_bh);
                 if (status < 0) {
                         mlog_errno(status);
                         goto bail;
                 }
         }
 
 bail:
         if (status < 0) {
                 if (ret_bh && (*ret_bh)) {
                         brelse(*ret_bh);
                         *ret_bh = NULL;
                 }
                 if (acquired)
                         ocfs2_inode_unlock(inode, ex);
         }
 
         brelse(local_bh);
         return status;
 }
 
 /*
  * This is working around a lock inversion between tasks acquiring DLM
  * locks while holding a page lock and the downconvert thread which
  * blocks dlm lock acquiry while acquiring page locks.
  *
  * ** These _with_page variantes are only intended to be called from aop
  * methods that hold page locks and return a very specific *positive* error
  * code that aop methods pass up to the VFS -- test for errors with != 0. **
  *
  * The DLM is called such that it returns -EAGAIN if it would have
  * blocked waiting for the downconvert thread.  In that case we unlock
  * our page so the downconvert thread can make progress.  Once we've
  * done this we have to return AOP_TRUNCATED_PAGE so the aop method
  * that called us can bubble that back up into the VFS who will then
  * immediately retry the aop call.
  */
 int ocfs2_inode_lock_with_page(struct inode *inode,
                               struct buffer_head **ret_bh,
                               int ex,
                               struct page *page)
 {
         int ret;
 
         ret = ocfs2_inode_lock_full(inode, ret_bh, ex, OCFS2_LOCK_NONBLOCK);
         if (ret == -EAGAIN) {
                 unlock_page(page);
                 /*
                  * If we can't get inode lock immediately, we should not return
                  * directly here, since this will lead to a softlockup problem.
                  * The method is to get a blocking lock and immediately unlock
                  * before returning, this can avoid CPU resource waste due to
                  * lots of retries, and benefits fairness in getting lock.
                  */
                 if (ocfs2_inode_lock(inode, ret_bh, ex) == 0)
                         ocfs2_inode_unlock(inode, ex);
                 ret = AOP_TRUNCATED_PAGE;
         }
 
         return ret;
 }
 
 int ocfs2_inode_lock_atime(struct inode *inode,
                           struct vfsmount *vfsmnt,
                           int *level, int wait)
 {
         int ret;
 
         if (wait)
                 ret = ocfs2_inode_lock(inode, NULL, 0);
         else
                 ret = ocfs2_try_inode_lock(inode, NULL, 0);
 
         if (ret < 0) {
                 if (ret != -EAGAIN)
                         mlog_errno(ret);
                 return ret;
         }
 
         /*
          * If we should update atime, we will get EX lock,
          * otherwise we just get PR lock.
          */
         if (ocfs2_should_update_atime(inode, vfsmnt)) {
                 struct buffer_head *bh = NULL;
 
                 ocfs2_inode_unlock(inode, 0);
                 if (wait)
                         ret = ocfs2_inode_lock(inode, &bh, 1);
                 else
                         ret = ocfs2_try_inode_lock(inode, &bh, 1);
 
                 if (ret < 0) {
                         if (ret != -EAGAIN)
                                 mlog_errno(ret);
                         return ret;
                 }
                 *level = 1;
                 if (ocfs2_should_update_atime(inode, vfsmnt))
                         ocfs2_update_inode_atime(inode, bh);
                 brelse(bh);
         } else
                 *level = 0;
 
         return ret;
 }
 
 void ocfs2_inode_unlock(struct inode *inode,
                        int ex)
 {
         int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_inode_lockres;
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
         mlog(0, "inode %llu drop %s META lock\n",
              (unsigned long long)OCFS2_I(inode)->ip_blkno,
              ex ? "EXMODE" : "PRMODE");
 
         if (!ocfs2_is_hard_readonly(osb) &&
             !ocfs2_mount_local(osb))
                 ocfs2_cluster_unlock(osb, lockres, level);
 }
 
 /*
  * This _tracker variantes are introduced to deal with the recursive cluster
  * locking issue. The idea is to keep track of a lock holder on the stack of
  * the current process. If there's a lock holder on the stack, we know the
  * task context is already protected by cluster locking. Currently, they're
  * used in some VFS entry routines.
  *
  * return < 0 on error, return == 0 if there's no lock holder on the stack
  * before this call, return == 1 if this call would be a recursive locking.
  * return == -1 if this lock attempt will cause an upgrade which is forbidden.
  *
  * When taking lock levels into account,we face some different situations.
  *
  * 1. no lock is held
  *    In this case, just lock the inode as requested and return 0
  *
  * 2. We are holding a lock
  *    For this situation, things diverges into several cases
  *
  *    wanted     holding             what to do
  *    ex                ex          see 2.1 below
  *    ex                pr          see 2.2 below
  *    pr                ex          see 2.1 below
  *    pr                pr          see 2.1 below
  *
  *    2.1 lock level that is been held is compatible
  *    with the wanted level, so no lock action will be tacken.
  *
  *    2.2 Otherwise, an upgrade is needed, but it is forbidden.
  *
  * Reason why upgrade within a process is forbidden is that
  * lock upgrade may cause dead lock. The following illustrates
  * how it happens.
  *
  *         thread on node1                             thread on node2
  * ocfs2_inode_lock_tracker(ex=0)
  *
  *                                <======   ocfs2_inode_lock_tracker(ex=1)
  *
  * ocfs2_inode_lock_tracker(ex=1)
  */
 int ocfs2_inode_lock_tracker(struct inode *inode,
                              struct buffer_head **ret_bh,
                              int ex,
                              struct ocfs2_lock_holder *oh)
 {
         int status = 0;
         struct ocfs2_lock_res *lockres;
         struct ocfs2_lock_holder *tmp_oh;
         struct pid *pid = task_pid(current);
 
 
         lockres = &OCFS2_I(inode)->ip_inode_lockres;
         tmp_oh = ocfs2_pid_holder(lockres, pid);
 
         if (!tmp_oh) {
                 /*
                  * This corresponds to the case 1.
                  * We haven't got any lock before.
                  */
                 status = ocfs2_inode_lock_full(inode, ret_bh, ex, 0);
                 if (status < 0) {
                         if (status != -ENOENT)
                                 mlog_errno(status);
                         return status;
                 }
 
                 oh->oh_ex = ex;
                 ocfs2_add_holder(lockres, oh);
                 return 0;
         }
 
         if (unlikely(ex && !tmp_oh->oh_ex)) {
                 /*
                  * case 2.2 upgrade may cause dead lock, forbid it.
                  */
                 mlog(ML_ERROR, "Recursive locking is not permitted to "
                      "upgrade to EX level from PR level.\n");
                 dump_stack();
                 return -EINVAL;
         }
 
         /*
          *  case 2.1 OCFS2_META_LOCK_GETBH flag make ocfs2_inode_lock_full.
          *  ignore the lock level and just update it.
          */
         if (ret_bh) {
                 status = ocfs2_inode_lock_full(inode, ret_bh, ex,
                                                OCFS2_META_LOCK_GETBH);
                 if (status < 0) {
                         if (status != -ENOENT)
                                 mlog_errno(status);
                         return status;
                 }
         }
         return 1;
 }
 
 void ocfs2_inode_unlock_tracker(struct inode *inode,
                                 int ex,
                                 struct ocfs2_lock_holder *oh,
                                 int had_lock)
 {
         struct ocfs2_lock_res *lockres;
 
         lockres = &OCFS2_I(inode)->ip_inode_lockres;
         /* had_lock means that the currect process already takes the cluster
          * lock previously.
          * If had_lock is 1, we have nothing to do here.
          * If had_lock is 0, we will release the lock.
          */
         if (!had_lock) {
                 ocfs2_inode_unlock(inode, oh->oh_ex);
                 ocfs2_remove_holder(lockres, oh);
         }
 }
 
 int ocfs2_orphan_scan_lock(struct ocfs2_super *osb, u32 *seqno)
 {
         struct ocfs2_lock_res *lockres;
         struct ocfs2_orphan_scan_lvb *lvb;
         int status = 0;
 
         if (ocfs2_is_hard_readonly(osb))
                 return -EROFS;
 
         if (ocfs2_mount_local(osb))
                 return 0;
 
         lockres = &osb->osb_orphan_scan.os_lockres;
         status = ocfs2_cluster_lock(osb, lockres, DLM_LOCK_EX, 0, 0);
         if (status < 0)
                 return status;
 
         lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
         if (ocfs2_dlm_lvb_valid(&lockres->l_lksb) &&
             lvb->lvb_version == OCFS2_ORPHAN_LVB_VERSION)
                 *seqno = be32_to_cpu(lvb->lvb_os_seqno);
         else
                 *seqno = osb->osb_orphan_scan.os_seqno + 1;
 
         return status;
 }
 
 void ocfs2_orphan_scan_unlock(struct ocfs2_super *osb, u32 seqno)
 {
         struct ocfs2_lock_res *lockres;
         struct ocfs2_orphan_scan_lvb *lvb;
 
         if (!ocfs2_is_hard_readonly(osb) && !ocfs2_mount_local(osb)) {
                 lockres = &osb->osb_orphan_scan.os_lockres;
                 lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
                 lvb->lvb_version = OCFS2_ORPHAN_LVB_VERSION;
                 lvb->lvb_os_seqno = cpu_to_be32(seqno);
                 ocfs2_cluster_unlock(osb, lockres, DLM_LOCK_EX);
         }
 }
 
 int ocfs2_super_lock(struct ocfs2_super *osb,
                      int ex)
 {
         int status = 0;
         int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         struct ocfs2_lock_res *lockres = &osb->osb_super_lockres;
 
         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) {
                 status = ocfs2_refresh_slot_info(osb);
 
                 ocfs2_complete_lock_res_refresh(lockres, status);
 
                 if (status < 0) {
                         ocfs2_cluster_unlock(osb, lockres, level);
                         mlog_errno(status);
                 }
                 ocfs2_track_lock_refresh(lockres);
         }
 bail:
         return status;
 }
 
 void ocfs2_super_unlock(struct ocfs2_super *osb,
                         int ex)
 {
         int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         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, DLM_LOCK_EX, 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, DLM_LOCK_EX);
 }
 
 int ocfs2_nfs_sync_lock(struct ocfs2_super *osb, int ex)
 {
         int status;
         struct ocfs2_lock_res *lockres = &osb->osb_nfs_sync_lockres;
 
         if (ocfs2_is_hard_readonly(osb))
                 return -EROFS;
 
         if (ex)
                 down_write(&osb->nfs_sync_rwlock);
         else
                 down_read(&osb->nfs_sync_rwlock);
 
         if (ocfs2_mount_local(osb))
                 return 0;
 
         status = ocfs2_cluster_lock(osb, lockres, ex ? LKM_EXMODE : LKM_PRMODE,
                                     0, 0);
         if (status < 0) {
                 mlog(ML_ERROR, "lock on nfs sync lock failed %d\n", status);
 
                 if (ex)
                         up_write(&osb->nfs_sync_rwlock);
                 else
                         up_read(&osb->nfs_sync_rwlock);
         }
 
         return status;
 }
 
 void ocfs2_nfs_sync_unlock(struct ocfs2_super *osb, int ex)
 {
         struct ocfs2_lock_res *lockres = &osb->osb_nfs_sync_lockres;
 
         if (!ocfs2_mount_local(osb))
                 ocfs2_cluster_unlock(osb, lockres,
                                      ex ? LKM_EXMODE : LKM_PRMODE);
         if (ex)
                 up_write(&osb->nfs_sync_rwlock);
         else
                 up_read(&osb->nfs_sync_rwlock);
 }
 
 int ocfs2_trim_fs_lock(struct ocfs2_super *osb,
                        struct ocfs2_trim_fs_info *info, int trylock)
 {
         int status;
         struct ocfs2_trim_fs_lvb *lvb;
         struct ocfs2_lock_res *lockres = &osb->osb_trim_fs_lockres;
 
         if (info)
                 info->tf_valid = 0;
 
         if (ocfs2_is_hard_readonly(osb))
                 return -EROFS;
 
         if (ocfs2_mount_local(osb))
                 return 0;
 
         status = ocfs2_cluster_lock(osb, lockres, DLM_LOCK_EX,
                                     trylock ? DLM_LKF_NOQUEUE : 0, 0);
         if (status < 0) {
                 if (status != -EAGAIN)
                         mlog_errno(status);
                 return status;
         }
 
         if (info) {
                 lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
                 if (ocfs2_dlm_lvb_valid(&lockres->l_lksb) &&
                     lvb->lvb_version == OCFS2_TRIMFS_LVB_VERSION) {
                         info->tf_valid = 1;
                         info->tf_success = lvb->lvb_success;
                         info->tf_nodenum = be32_to_cpu(lvb->lvb_nodenum);
                         info->tf_start = be64_to_cpu(lvb->lvb_start);
                         info->tf_len = be64_to_cpu(lvb->lvb_len);
                         info->tf_minlen = be64_to_cpu(lvb->lvb_minlen);
                         info->tf_trimlen = be64_to_cpu(lvb->lvb_trimlen);
                 }
         }
 
         return status;
 }
 
 void ocfs2_trim_fs_unlock(struct ocfs2_super *osb,
                           struct ocfs2_trim_fs_info *info)
 {
         struct ocfs2_trim_fs_lvb *lvb;
         struct ocfs2_lock_res *lockres = &osb->osb_trim_fs_lockres;
 
         if (ocfs2_mount_local(osb))
                 return;
 
         if (info) {
                 lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
                 lvb->lvb_version = OCFS2_TRIMFS_LVB_VERSION;
                 lvb->lvb_success = info->tf_success;
                 lvb->lvb_nodenum = cpu_to_be32(info->tf_nodenum);
                 lvb->lvb_start = cpu_to_be64(info->tf_start);
                 lvb->lvb_len = cpu_to_be64(info->tf_len);
                 lvb->lvb_minlen = cpu_to_be64(info->tf_minlen);
                 lvb->lvb_trimlen = cpu_to_be64(info->tf_trimlen);
         }
 
         ocfs2_cluster_unlock(osb, lockres, DLM_LOCK_EX);
 }
 
 int ocfs2_dentry_lock(struct dentry *dentry, int ex)
 {
         int ret;
         int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         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)) {
                 if (ex)
                         return -EROFS;
                 return 0;
         }
 
         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 ? DLM_LOCK_EX : DLM_LOCK_PR;
         struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
         struct ocfs2_super *osb = OCFS2_SB(dentry->d_sb);
 
         if (!ocfs2_is_hard_readonly(osb) && !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_filter_secs = 0;
 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;
 }
 
 /*
  * Version is used by debugfs.ocfs2 to determine the format being used
  *
  * New in version 2
  *      - Lock stats printed
  * New in version 3
  *      - Max time in lock stats is in usecs (instead of nsecs)
  * New in version 4
  *      - Add last pr/ex unlock times and first lock wait time in usecs
  */
 #define OCFS2_DLM_DEBUG_STR_VERSION 4
 static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
 {
         int i;
         char *lvb;
         struct ocfs2_lock_res *lockres = v;
 #ifdef CONFIG_OCFS2_FS_STATS
         u64 now, last;
         struct ocfs2_dlm_debug *dlm_debug =
                         ((struct ocfs2_dlm_seq_priv *)m->private)->p_dlm_debug;
 #endif
 
         if (!lockres)
                 return -EINVAL;
 
 #ifdef CONFIG_OCFS2_FS_STATS
         if (!lockres->l_lock_wait && dlm_debug->d_filter_secs) {
                 now = ktime_to_us(ktime_get_real());
                 if (lockres->l_lock_prmode.ls_last >
                     lockres->l_lock_exmode.ls_last)
                         last = lockres->l_lock_prmode.ls_last;
                 else
                         last = lockres->l_lock_exmode.ls_last;
                 /*
                  * Use d_filter_secs field to filter lock resources dump,
                  * the default d_filter_secs(0) value filters nothing,
                  * otherwise, only dump the last N seconds active lock
                  * resources.
                  */
                 if (div_u64(now - last, 1000000) > dlm_debug->d_filter_secs)
                         return 0;
         }
 #endif
 
         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 = ocfs2_dlm_lvb(&lockres->l_lksb);
         for(i = 0; i < DLM_LVB_LEN; i++)
                 seq_printf(m, "0x%x\t", lvb[i]);
 
 #ifdef CONFIG_OCFS2_FS_STATS
 # define lock_num_prmode(_l)            ((_l)->l_lock_prmode.ls_gets)
 # define lock_num_exmode(_l)            ((_l)->l_lock_exmode.ls_gets)
 # define lock_num_prmode_failed(_l)     ((_l)->l_lock_prmode.ls_fail)
 # define lock_num_exmode_failed(_l)     ((_l)->l_lock_exmode.ls_fail)
 # define lock_total_prmode(_l)          ((_l)->l_lock_prmode.ls_total)
 # define lock_total_exmode(_l)          ((_l)->l_lock_exmode.ls_total)
 # define lock_max_prmode(_l)            ((_l)->l_lock_prmode.ls_max)
 # define lock_max_exmode(_l)            ((_l)->l_lock_exmode.ls_max)
 # define lock_refresh(_l)               ((_l)->l_lock_refresh)
 # define lock_last_prmode(_l)           ((_l)->l_lock_prmode.ls_last)
 # define lock_last_exmode(_l)           ((_l)->l_lock_exmode.ls_last)
 # define lock_wait(_l)                  ((_l)->l_lock_wait)
 #else
 # define lock_num_prmode(_l)            (0)
 # define lock_num_exmode(_l)            (0)
 # define lock_num_prmode_failed(_l)     (0)
 # define lock_num_exmode_failed(_l)     (0)
 # define lock_total_prmode(_l)          (0ULL)
 # define lock_total_exmode(_l)          (0ULL)
 # define lock_max_prmode(_l)            (0)
 # define lock_max_exmode(_l)            (0)
 # define lock_refresh(_l)               (0)
 # define lock_last_prmode(_l)           (0ULL)
 # define lock_last_exmode(_l)           (0ULL)
 # define lock_wait(_l)                  (0ULL)
 #endif
         /* The following seq_print was added in version 2 of this output */
         seq_printf(m, "%u\t"
                    "%u\t"
                    "%u\t"
                    "%u\t"
                    "%llu\t"
                    "%llu\t"
                    "%u\t"
                    "%u\t"
                    "%u\t"
                    "%llu\t"
                    "%llu\t"
                    "%llu\t",
                    lock_num_prmode(lockres),
                    lock_num_exmode(lockres),
                    lock_num_prmode_failed(lockres),
                    lock_num_exmode_failed(lockres),
                    lock_total_prmode(lockres),
                    lock_total_exmode(lockres),
                    lock_max_prmode(lockres),
                    lock_max_exmode(lockres),
                    lock_refresh(lockres),
                    lock_last_prmode(lockres),
                    lock_last_exmode(lockres),
                    lock_wait(lockres));
 
         /* End the line */
         seq_printf(m, "\n");
         return 0;
 }
 
 static const 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 = 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)
 {
         struct ocfs2_dlm_seq_priv *priv;
         struct ocfs2_super *osb;
 
         priv = __seq_open_private(file, &ocfs2_dlm_seq_ops, sizeof(*priv));
         if (!priv) {
                 mlog_errno(-ENOMEM);
                 return -ENOMEM;
         }
 
         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);
 
         ocfs2_add_lockres_tracking(&priv->p_iter_res,
                                    priv->p_dlm_debug);
 
         return 0;
 }
 
 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 void ocfs2_dlm_init_debug(struct ocfs2_super *osb)
 {
         struct ocfs2_dlm_debug *dlm_debug = osb->osb_dlm_debug;
 
         debugfs_create_file("locking_state", S_IFREG|S_IRUSR,
                             osb->osb_debug_root, osb, &ocfs2_dlm_debug_fops);
 
         debugfs_create_u32("locking_filter", 0600, osb->osb_debug_root,
                            &dlm_debug->d_filter_secs);
         ocfs2_get_dlm_debug(dlm_debug);
 }
 
 static void ocfs2_dlm_shutdown_debug(struct ocfs2_super *osb)
 {
         struct ocfs2_dlm_debug *dlm_debug = osb->osb_dlm_debug;
 
         if (dlm_debug)
                 ocfs2_put_dlm_debug(dlm_debug);
 }
 
 int ocfs2_dlm_init(struct ocfs2_super *osb)
 {
         int status = 0;
         struct ocfs2_cluster_connection *conn = NULL;
 
         if (ocfs2_mount_local(osb)) {
                 osb->node_num = 0;
                 goto local;
         }
 
         ocfs2_dlm_init_debug(osb);
 
         /* launch downconvert thread */
         osb->dc_task = kthread_run(ocfs2_downconvert_thread, osb, "ocfs2dc-%s",
                         osb->uuid_str);
         if (IS_ERR(osb->dc_task)) {
                 status = PTR_ERR(osb->dc_task);
                 osb->dc_task = NULL;
                 mlog_errno(status);
                 goto bail;
         }
 
         /* for now, uuid == domain */
         status = ocfs2_cluster_connect(osb->osb_cluster_stack,
                                        osb->osb_cluster_name,
                                        strlen(osb->osb_cluster_name),
                                        osb->uuid_str,
                                        strlen(osb->uuid_str),
                                        &lproto, ocfs2_do_node_down, osb,
                                        &conn);
         if (status) {
                 mlog_errno(status);
                 goto bail;
         }
 
         status = ocfs2_cluster_this_node(conn, &osb->node_num);
         if (status < 0) {
                 mlog_errno(status);
                 mlog(ML_ERROR,
                      "could not find this host's node number\n");
                 ocfs2_cluster_disconnect(conn, 0);
                 goto bail;
         }
 
 local:
         ocfs2_super_lock_res_init(&osb->osb_super_lockres, osb);
         ocfs2_rename_lock_res_init(&osb->osb_rename_lockres, osb);
         ocfs2_nfs_sync_lock_init(osb);
         ocfs2_orphan_scan_lock_res_init(&osb->osb_orphan_scan.os_lockres, osb);
 
         osb->cconn = conn;
 bail:
         if (status < 0) {
                 ocfs2_dlm_shutdown_debug(osb);
                 if (osb->dc_task)
                         kthread_stop(osb->dc_task);
         }
 
         return status;
 }
 
 void ocfs2_dlm_shutdown(struct ocfs2_super *osb,
                         int hangup_pending)
 {
         ocfs2_drop_osb_locks(osb);
 
         /*
          * Now that we have dropped all locks and ocfs2_dismount_volume()
          * has disabled recovery, the DLM won't be talking to us.  It's
          * safe to tear things down before disconnecting the cluster.
          */
 
         if (osb->dc_task) {
                 kthread_stop(osb->dc_task);
                 osb->dc_task = NULL;
         }
 
         ocfs2_lock_res_free(&osb->osb_super_lockres);
         ocfs2_lock_res_free(&osb->osb_rename_lockres);
         ocfs2_lock_res_free(&osb->osb_nfs_sync_lockres);
         ocfs2_lock_res_free(&osb->osb_orphan_scan.os_lockres);
 
         if (osb->cconn) {
                 ocfs2_cluster_disconnect(osb->cconn, hangup_pending);
                 osb->cconn = NULL;
 
                 ocfs2_dlm_shutdown_debug(osb);
         }
 }
 
 static int ocfs2_drop_lock(struct ocfs2_super *osb,
                            struct ocfs2_lock_res *lockres)
 {
         int ret;
         unsigned long flags;
         u32 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 |= DLM_LKF_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 == DLM_LOCK_EX &&
                     !(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);
 
         ret = ocfs2_dlm_unlock(osb->cconn, &lockres->l_lksb, lkm_flags);
         if (ret) {
                 ocfs2_log_dlm_error("ocfs2_dlm_unlock", ret, lockres);
                 mlog(ML_ERROR, "lockres flags: %lu\n", lockres->l_flags);
                 ocfs2_dlm_dump_lksb(&lockres->l_lksb);
                 BUG();
         }
         mlog(0, "lock %s, successful return from ocfs2_dlm_unlock\n",
              lockres->l_name);
 
         ocfs2_wait_on_busy_lock(lockres);
 out:
         return 0;
 }
 
 static void ocfs2_process_blocked_lock(struct ocfs2_super *osb,
                                        struct ocfs2_lock_res *lockres);
 
 /* 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 downconvert 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_super *osb,
                                 struct ocfs2_lock_res *lockres)
 {
         int status;
         struct ocfs2_mask_waiter mw;
         unsigned long flags, flags2;
 
         ocfs2_init_mask_waiter(&mw);
 
         spin_lock_irqsave(&lockres->l_lock, flags);
         lockres->l_flags |= OCFS2_LOCK_FREEING;
         if (lockres->l_flags & OCFS2_LOCK_QUEUED && current == osb->dc_task) {
                 /*
                  * We know the downconvert is queued but not in progress
                  * because we are the downconvert thread and processing
                  * different lock. So we can just remove the lock from the
                  * queue. This is not only an optimization but also a way
                  * to avoid the following deadlock:
                  *   ocfs2_dentry_post_unlock()
                  *     ocfs2_dentry_lock_put()
                  *       ocfs2_drop_dentry_lock()
                  *         iput()
                  *           ocfs2_evict_inode()
                  *             ocfs2_clear_inode()
                  *               ocfs2_mark_lockres_freeing()
                  *                 ... blocks waiting for OCFS2_LOCK_QUEUED
                  *                 since we are the downconvert thread which
                  *                 should clear the flag.
                  */
                 spin_unlock_irqrestore(&lockres->l_lock, flags);
                 spin_lock_irqsave(&osb->dc_task_lock, flags2);
                 list_del_init(&lockres->l_blocked_list);
                 osb->blocked_lock_count--;
                 spin_unlock_irqrestore(&osb->dc_task_lock, flags2);
                 /*
                  * Warn if we recurse into another post_unlock call.  Strictly
                  * speaking it isn't a problem but we need to be careful if
                  * that happens (stack overflow, deadlocks, ...) so warn if
                  * ocfs2 grows a path for which this can happen.
                  */
                 WARN_ON_ONCE(lockres->l_ops->post_unlock);
                 /* Since the lock is freeing we don't do much in the fn below */
                 ocfs2_process_blocked_lock(osb, lockres);
                 return;
         }
         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(osb, 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);
         ocfs2_simple_drop_lockres(osb, &osb->osb_nfs_sync_lockres);
         ocfs2_simple_drop_lockres(osb, &osb->osb_orphan_scan.os_lockres);
 }
 
 int ocfs2_drop_inode_locks(struct inode *inode)
 {
         int status, err;
 
         /* 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_inode_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;
 
         return status;
 }
 
 static unsigned int ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
                                               int new_level)
 {
         assert_spin_locked(&lockres->l_lock);
 
         BUG_ON(lockres->l_blocking <= DLM_LOCK_NL);
 
         if (lockres->l_level <= new_level) {
                 mlog(ML_ERROR, "lockres %s, lvl %d <= %d, blcklst %d, mask %d, "
                      "type %d, flags 0x%lx, hold %d %d, act %d %d, req %d, "
                      "block %d, pgen %d\n", lockres->l_name, lockres->l_level,
                      new_level, list_empty(&lockres->l_blocked_list),
                      list_empty(&lockres->l_mask_waiters), lockres->l_type,
                      lockres->l_flags, lockres->l_ro_holders,
                      lockres->l_ex_holders, lockres->l_action,
                      lockres->l_unlock_action, lockres->l_requested,
                      lockres->l_blocking, lockres->l_pending_gen);
                 BUG();
         }
 
         mlog(ML_BASTS, "lockres %s, level %d => %d, blocking %d\n",
              lockres->l_name, lockres->l_level, new_level, lockres->l_blocking);
 
         lockres->l_action = OCFS2_AST_DOWNCONVERT;
         lockres->l_requested = new_level;
         lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
         return lockres_set_pending(lockres);
 }
 
 static int ocfs2_downconvert_lock(struct ocfs2_super *osb,
                                   struct ocfs2_lock_res *lockres,
                                   int new_level,
                                   int lvb,
                                   unsigned int generation)
 {
         int ret;
         u32 dlm_flags = DLM_LKF_CONVERT;
 
         mlog(ML_BASTS, "lockres %s, level %d => %d\n", lockres->l_name,
              lockres->l_level, new_level);
 
         /*
          * On DLM_LKF_VALBLK, fsdlm behaves differently with o2cb. It always
          * expects DLM_LKF_VALBLK being set if the LKB has LVB, so that
          * we can recover correctly from node failure. Otherwise, we may get
          * invalid LVB in LKB, but without DLM_SBF_VALNOTVALID being set.
          */
         if (ocfs2_userspace_stack(osb) &&
             lockres->l_ops->flags & LOCK_TYPE_USES_LVB)
                 lvb = 1;
 
         if (lvb)
                 dlm_flags |= DLM_LKF_VALBLK;
 
         ret = ocfs2_dlm_lock(osb->cconn,
                              new_level,
                              &lockres->l_lksb,
                              dlm_flags,
                              lockres->l_name,
                              OCFS2_LOCK_ID_MAX_LEN - 1);
         lockres_clear_pending(lockres, generation, osb);
         if (ret) {
                 ocfs2_log_dlm_error("ocfs2_dlm_lock", ret, lockres);
                 ocfs2_recover_from_dlm_error(lockres, 1);
                 goto bail;
         }
 
         ret = 0;
 bail:
         return ret;
 }
 
 /* returns 1 when the caller should unlock and call ocfs2_dlm_unlock */
 static int ocfs2_prepare_cancel_convert(struct ocfs2_super *osb,
                                         struct ocfs2_lock_res *lockres)
 {
         assert_spin_locked(&lockres->l_lock);
 
         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(ML_BASTS, "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);
 
         mlog(ML_BASTS, "lockres %s\n", lockres->l_name);
 
         return 1;
 }
 
 static int ocfs2_cancel_convert(struct ocfs2_super *osb,
                                 struct ocfs2_lock_res *lockres)
 {
         int ret;
 
         ret = ocfs2_dlm_unlock(osb->cconn, &lockres->l_lksb,
                                DLM_LKF_CANCEL);
         if (ret) {
                 ocfs2_log_dlm_error("ocfs2_dlm_unlock", ret, lockres);
                 ocfs2_recover_from_dlm_error(lockres, 0);
         }
 
         mlog(ML_BASTS, "lockres %s\n", lockres->l_name);
 
         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 level;
         int ret = 0;
         int set_lvb = 0;
         unsigned int gen;
 
         spin_lock_irqsave(&lockres->l_lock, flags);
 
 recheck:
         /*
          * Is it still blocking? If not, we have no more work to do.
          */
         if (!(lockres->l_flags & OCFS2_LOCK_BLOCKED)) {
                 BUG_ON(lockres->l_blocking != DLM_LOCK_NL);
                 spin_unlock_irqrestore(&lockres->l_lock, flags);
                 ret = 0;
                 goto leave;
         }
 
         if (lockres->l_flags & OCFS2_LOCK_BUSY) {
                 /* XXX
                  * This is a *big* race.  The OCFS2_LOCK_PENDING flag
                  * exists entirely for one reason - another thread has set
                  * OCFS2_LOCK_BUSY, but has *NOT* yet called dlm_lock().
                  *
                  * If we do ocfs2_cancel_convert() before the other thread
                  * calls dlm_lock(), our cancel will do nothing.  We will
                  * get no ast, and we will have no way of knowing the
                  * cancel failed.  Meanwhile, the other thread will call
                  * into dlm_lock() and wait...forever.
                  *
                  * Why forever?  Because another node has asked for the
                  * lock first; that's why we're here in unblock_lock().
                  *
                  * The solution is OCFS2_LOCK_PENDING.  When PENDING is
                  * set, we just requeue the unblock.  Only when the other
                  * thread has called dlm_lock() and cleared PENDING will
                  * we then cancel their request.
                  *
                  * All callers of dlm_lock() must set OCFS2_DLM_PENDING
                  * at the same time they set OCFS2_DLM_BUSY.  They must
                  * clear OCFS2_DLM_PENDING after dlm_lock() returns.
                  */
                 if (lockres->l_flags & OCFS2_LOCK_PENDING) {
                         mlog(ML_BASTS, "lockres %s, ReQ: Pending\n",
                              lockres->l_name);
                         goto leave_requeue;
                 }
 
                 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;
         }
 
         /*
          * This prevents livelocks. OCFS2_LOCK_UPCONVERT_FINISHING flag is
          * set when the ast is received for an upconvert just before the
          * OCFS2_LOCK_BUSY flag is cleared. Now if the fs received a bast
          * on the heels of the ast, we want to delay the downconvert just
          * enough to allow the up requestor to do its task. Because this
          * lock is in the blocked queue, the lock will be downconverted
          * as soon as the requestor is done with the lock.
          */
         if (lockres->l_flags & OCFS2_LOCK_UPCONVERT_FINISHING)
                 goto leave_requeue;
 
         /*
          * How can we block and yet be at NL?  We were trying to upconvert
          * from NL and got canceled.  The code comes back here, and now
          * we notice and clear BLOCKING.
          */
         if (lockres->l_level == DLM_LOCK_NL) {
                 BUG_ON(lockres->l_ex_holders || lockres->l_ro_holders);
                 mlog(ML_BASTS, "lockres %s, Aborting dc\n", lockres->l_name);
                 lockres->l_blocking = DLM_LOCK_NL;
                 lockres_clear_flags(lockres, OCFS2_LOCK_BLOCKED);
                 spin_unlock_irqrestore(&lockres->l_lock, flags);
                 goto leave;
         }
 
         /* if we're blocking an exclusive and we have *any* holders,
          * then requeue. */
         if ((lockres->l_blocking == DLM_LOCK_EX)
             && (lockres->l_ex_holders || lockres->l_ro_holders)) {
                 mlog(ML_BASTS, "lockres %s, ReQ: EX/PR Holders %u,%u\n",
                      lockres->l_name, 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 == DLM_LOCK_PR &&
             lockres->l_ex_holders) {
                 mlog(ML_BASTS, "lockres %s, ReQ: EX Holders %u\n",
                      lockres->l_name, 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)) {
                 mlog(ML_BASTS, "lockres %s, ReQ: Lock Refreshing\n",
                      lockres->l_name);
                 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)) {
                 mlog(ML_BASTS, "lockres %s, ReQ: Checkpointing\n",
                      lockres->l_name);
                 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;
         level = lockres->l_level;
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
         ctl->unblock_action = lockres->l_ops->downconvert_worker(lockres, blocking);
 
         if (ctl->unblock_action == UNBLOCK_STOP_POST) {
                 mlog(ML_BASTS, "lockres %s, UNBLOCK_STOP_POST\n",
                      lockres->l_name);
                 goto leave;
         }
 
         spin_lock_irqsave(&lockres->l_lock, flags);
         if ((blocking != lockres->l_blocking) || (level != lockres->l_level)) {
                 /* If this changed underneath us, then we can't drop
                  * it just yet. */
                 mlog(ML_BASTS, "lockres %s, block=%d:%d, level=%d:%d, "
                      "Recheck\n", lockres->l_name, blocking,
                      lockres->l_blocking, level, lockres->l_level);
                 goto recheck;
         }
 
 downconvert:
         ctl->requeue = 0;
 
         if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB) {
                 if (lockres->l_level == DLM_LOCK_EX)
                         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);
         }
 
         gen = ocfs2_prepare_downconvert(lockres, new_level);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
         ret = ocfs2_downconvert_lock(osb, lockres, new_level, set_lvb,
                                      gen);
         /* The dlm lock convert is being cancelled in background,
          * ocfs2_cancel_convert() is asynchronous in fs/dlm,
          * requeue it, try again later.
          */
         if (ret == -EBUSY) {
                 ctl->requeue = 1;
                 mlog(ML_BASTS, "lockres %s, ReQ: Downconvert busy\n",
                      lockres->l_name);
                 ret = 0;
                 msleep(20);
         }
 
 leave:
         if (ret)
                 mlog_errno(ret);
         return ret;
 
 leave_requeue:
         spin_unlock_irqrestore(&lockres->l_lock, flags);
         ctl->requeue = 1;
 
         return 0;
 }
 
 static int ocfs2_data_convert_worker(struct ocfs2_lock_res *lockres,
                                      int blocking)
 {
         struct inode *inode;
         struct address_space *mapping;
         struct ocfs2_inode_info *oi;
 
         inode = ocfs2_lock_res_inode(lockres);
         mapping = inode->i_mapping;
 
         if (S_ISDIR(inode->i_mode)) {
                 oi = OCFS2_I(inode);
                 oi->ip_dir_lock_gen++;
                 mlog(0, "generation: %u\n", oi->ip_dir_lock_gen);
                 goto out_forget;
         }
 
         if (!S_ISREG(inode->i_mode))
                 goto out;
 
         /*
          * 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 == DLM_LOCK_EX) {
                 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);
         }
 
 out_forget:
         forget_all_cached_acls(inode);
 
 out:
         return UNBLOCK_CONTINUE;
 }
 
 static int ocfs2_ci_checkpointed(struct ocfs2_caching_info *ci,
                                  struct ocfs2_lock_res *lockres,
                                  int new_level)
 {
         int checkpointed = ocfs2_ci_fully_checkpointed(ci);
 
         BUG_ON(new_level != DLM_LOCK_NL && new_level != DLM_LOCK_PR);
         BUG_ON(lockres->l_level != DLM_LOCK_EX && !checkpointed);
 
         if (checkpointed)
                 return 1;
 
         ocfs2_start_checkpoint(OCFS2_SB(ocfs2_metadata_cache_get_super(ci)));
         return 0;
 }
 
 static int ocfs2_check_meta_downconvert(struct ocfs2_lock_res *lockres,
                                         int new_level)
 {
         struct inode *inode = ocfs2_lock_res_inode(lockres);
 
         return ocfs2_ci_checkpointed(INODE_CACHE(inode), lockres, new_level);
 }
 
 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 downconvert 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 == DLM_LOCK_PR)
                 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);
 
                 if (S_ISDIR(dl->dl_inode->i_mode))
                         shrink_dcache_parent(dentry);
 
                 mlog(0, "d_delete(%pd);\n", dentry);
 
                 /*
                  * 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;
 }
 
 static int ocfs2_check_refcount_downconvert(struct ocfs2_lock_res *lockres,
                                             int new_level)
 {
         struct ocfs2_refcount_tree *tree =
                                 ocfs2_lock_res_refcount_tree(lockres);
 
         return ocfs2_ci_checkpointed(&tree->rf_ci, lockres, new_level);
 }
 
 static int ocfs2_refcount_convert_worker(struct ocfs2_lock_res *lockres,
                                          int blocking)
 {
         struct ocfs2_refcount_tree *tree =
                                 ocfs2_lock_res_refcount_tree(lockres);
 
         ocfs2_metadata_cache_purge(&tree->rf_ci);
 
         return UNBLOCK_CONTINUE;
 }
 
 static void ocfs2_set_qinfo_lvb(struct ocfs2_lock_res *lockres)
 {
         struct ocfs2_qinfo_lvb *lvb;
         struct ocfs2_mem_dqinfo *oinfo = ocfs2_lock_res_qinfo(lockres);
         struct mem_dqinfo *info = sb_dqinfo(oinfo->dqi_gi.dqi_sb,
                                             oinfo->dqi_gi.dqi_type);
 
         lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
         lvb->lvb_version = OCFS2_QINFO_LVB_VERSION;
         lvb->lvb_bgrace = cpu_to_be32(info->dqi_bgrace);
         lvb->lvb_igrace = cpu_to_be32(info->dqi_igrace);
         lvb->lvb_syncms = cpu_to_be32(oinfo->dqi_syncms);
         lvb->lvb_blocks = cpu_to_be32(oinfo->dqi_gi.dqi_blocks);
         lvb->lvb_free_blk = cpu_to_be32(oinfo->dqi_gi.dqi_free_blk);
         lvb->lvb_free_entry = cpu_to_be32(oinfo->dqi_gi.dqi_free_entry);
 }
 
 void ocfs2_qinfo_unlock(struct ocfs2_mem_dqinfo *oinfo, int ex)
 {
         struct ocfs2_lock_res *lockres = &oinfo->dqi_gqlock;
         struct ocfs2_super *osb = OCFS2_SB(oinfo->dqi_gi.dqi_sb);
         int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
 
         if (!ocfs2_is_hard_readonly(osb) && !ocfs2_mount_local(osb))
                 ocfs2_cluster_unlock(osb, lockres, level);
 }
 
 static int ocfs2_refresh_qinfo(struct ocfs2_mem_dqinfo *oinfo)
 {
         struct mem_dqinfo *info = sb_dqinfo(oinfo->dqi_gi.dqi_sb,
                                             oinfo->dqi_gi.dqi_type);
         struct ocfs2_lock_res *lockres = &oinfo->dqi_gqlock;
         struct ocfs2_qinfo_lvb *lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
         struct buffer_head *bh = NULL;
         struct ocfs2_global_disk_dqinfo *gdinfo;
         int status = 0;
 
         if (ocfs2_dlm_lvb_valid(&lockres->l_lksb) &&
             lvb->lvb_version == OCFS2_QINFO_LVB_VERSION) {
                 info->dqi_bgrace = be32_to_cpu(lvb->lvb_bgrace);
                 info->dqi_igrace = be32_to_cpu(lvb->lvb_igrace);
                 oinfo->dqi_syncms = be32_to_cpu(lvb->lvb_syncms);
                 oinfo->dqi_gi.dqi_blocks = be32_to_cpu(lvb->lvb_blocks);
                 oinfo->dqi_gi.dqi_free_blk = be32_to_cpu(lvb->lvb_free_blk);
                 oinfo->dqi_gi.dqi_free_entry =
                                         be32_to_cpu(lvb->lvb_free_entry);
         } else {
                 status = ocfs2_read_quota_phys_block(oinfo->dqi_gqinode,
                                                      oinfo->dqi_giblk, &bh);
                 if (status) {
                         mlog_errno(status);
                         goto bail;
                 }
                 gdinfo = (struct ocfs2_global_disk_dqinfo *)
                                         (bh->b_data + OCFS2_GLOBAL_INFO_OFF);
                 info->dqi_bgrace = le32_to_cpu(gdinfo->dqi_bgrace);
                 info->dqi_igrace = le32_to_cpu(gdinfo->dqi_igrace);
                 oinfo->dqi_syncms = le32_to_cpu(gdinfo->dqi_syncms);
                 oinfo->dqi_gi.dqi_blocks = le32_to_cpu(gdinfo->dqi_blocks);
                 oinfo->dqi_gi.dqi_free_blk = le32_to_cpu(gdinfo->dqi_free_blk);
                 oinfo->dqi_gi.dqi_free_entry =
                                         le32_to_cpu(gdinfo->dqi_free_entry);
                 brelse(bh);
                 ocfs2_track_lock_refresh(lockres);
         }
 
 bail:
         return status;
 }
 
 /* Lock quota info, this function expects at least shared lock on the quota file
  * so that we can safely refresh quota info from disk. */
 int ocfs2_qinfo_lock(struct ocfs2_mem_dqinfo *oinfo, int ex)
 {
         struct ocfs2_lock_res *lockres = &oinfo->dqi_gqlock;
         struct ocfs2_super *osb = OCFS2_SB(oinfo->dqi_gi.dqi_sb);
         int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         int status = 0;
 
         /* On RO devices, locking really isn't needed... */
         if (ocfs2_is_hard_readonly(osb)) {
                 if (ex)
                         status = -EROFS;
                 goto bail;
         }
         if (ocfs2_mount_local(osb))
                 goto bail;
 
         status = ocfs2_cluster_lock(osb, lockres, level, 0, 0);
         if (status < 0) {
                 mlog_errno(status);
                 goto bail;
         }
         if (!ocfs2_should_refresh_lock_res(lockres))
                 goto bail;
         /* OK, we have the lock but we need to refresh the quota info */
         status = ocfs2_refresh_qinfo(oinfo);
         if (status)
                 ocfs2_qinfo_unlock(oinfo, ex);
         ocfs2_complete_lock_res_refresh(lockres, status);
 bail:
         return status;
 }
 
 int ocfs2_refcount_lock(struct ocfs2_refcount_tree *ref_tree, int ex)
 {
         int status;
         int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         struct ocfs2_lock_res *lockres = &ref_tree->rf_lockres;
         struct ocfs2_super *osb = lockres->l_priv;
 
 
         if (ocfs2_is_hard_readonly(osb))
                 return -EROFS;
 
         if (ocfs2_mount_local(osb))
                 return 0;
 
         status = ocfs2_cluster_lock(osb, lockres, level, 0, 0);
         if (status < 0)
                 mlog_errno(status);
 
         return status;
 }
 
 void ocfs2_refcount_unlock(struct ocfs2_refcount_tree *ref_tree, int ex)
 {
         int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         struct ocfs2_lock_res *lockres = &ref_tree->rf_lockres;
         struct ocfs2_super *osb = lockres->l_priv;
 
         if (!ocfs2_mount_local(osb))
                 ocfs2_cluster_unlock(osb, lockres, level);
 }
 
 static 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. */
 
         BUG_ON(!lockres);
         BUG_ON(!lockres->l_ops);
 
         mlog(ML_BASTS, "lockres %s blocked\n", lockres->l_name);
 
         /* Detect whether a lock has been marked as going away while
          * the downconvert 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(ML_BASTS, "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);
 }
 
 static void ocfs2_schedule_blocked_lock(struct ocfs2_super *osb,
                                         struct ocfs2_lock_res *lockres)
 {
         unsigned long flags;
 
         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(ML_BASTS, "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_irqsave(&osb->dc_task_lock, flags);
         if (list_empty(&lockres->l_blocked_list)) {
                 list_add_tail(&lockres->l_blocked_list,
                               &osb->blocked_lock_list);
                 osb->blocked_lock_count++;
         }
         spin_unlock_irqrestore(&osb->dc_task_lock, flags);
 }
 
 static void ocfs2_downconvert_thread_do_work(struct ocfs2_super *osb)
 {
         unsigned long processed;
         unsigned long flags;
         struct ocfs2_lock_res *lockres;
 
         spin_lock_irqsave(&osb->dc_task_lock, flags);
         /* grab this early so we know to try again if a state change and
          * wake happens part-way through our work  */
         osb->dc_work_sequence = osb->dc_wake_sequence;
 
         processed = osb->blocked_lock_count;
         /*
          * blocked lock processing in this loop might call iput which can
          * remove items off osb->blocked_lock_list. Downconvert up to
          * 'processed' number of locks, but stop short if we had some
          * removed in ocfs2_mark_lockres_freeing when downconverting.
          */
         while (processed && !list_empty(&osb->blocked_lock_list)) {
                 lockres = list_entry(osb->blocked_lock_list.next,
                                      struct ocfs2_lock_res, l_blocked_list);
                 list_del_init(&lockres->l_blocked_list);
                 osb->blocked_lock_count--;
                 spin_unlock_irqrestore(&osb->dc_task_lock, flags);
 
                 BUG_ON(!processed);
                 processed--;
 
                 ocfs2_process_blocked_lock(osb, lockres);
 
                 spin_lock_irqsave(&osb->dc_task_lock, flags);
         }
         spin_unlock_irqrestore(&osb->dc_task_lock, flags);
 }
 
 static int ocfs2_downconvert_thread_lists_empty(struct ocfs2_super *osb)
 {
         int empty = 0;
         unsigned long flags;
 
         spin_lock_irqsave(&osb->dc_task_lock, flags);
         if (list_empty(&osb->blocked_lock_list))
                 empty = 1;
 
         spin_unlock_irqrestore(&osb->dc_task_lock, flags);
         return empty;
 }
 
 static int ocfs2_downconvert_thread_should_wake(struct ocfs2_super *osb)
 {
         int should_wake = 0;
         unsigned long flags;
 
         spin_lock_irqsave(&osb->dc_task_lock, flags);
         if (osb->dc_work_sequence != osb->dc_wake_sequence)
                 should_wake = 1;
         spin_unlock_irqrestore(&osb->dc_task_lock, flags);
 
         return should_wake;
 }
 
 static int ocfs2_downconvert_thread(void *arg)
 {
         struct ocfs2_super *osb = arg;
 
         /* only quit once we've been asked to stop and there is no more
          * work available */
         while (!(kthread_should_stop() &&
                 ocfs2_downconvert_thread_lists_empty(osb))) {
 
                 wait_event_interruptible(osb->dc_event,
                                          ocfs2_downconvert_thread_should_wake(osb) ||
                                          kthread_should_stop());
 
                 mlog(0, "downconvert_thread: awoken\n");
 
                 ocfs2_downconvert_thread_do_work(osb);
         }
 
         osb->dc_task = NULL;
         return 0;
 }
 
 void ocfs2_wake_downconvert_thread(struct ocfs2_super *osb)
 {
         unsigned long flags;
 
         spin_lock_irqsave(&osb->dc_task_lock, flags);
         /* make sure the voting thread gets a swipe at whatever changes
          * the caller may have made to the voting state */
         osb->dc_wake_sequence++;
         spin_unlock_irqrestore(&osb->dc_task_lock, flags);
         wake_up(&osb->dc_event);
 }