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 // 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 struct ocfs2_lock_res_ops ocfs2_inode_rw_lops = {
     .get_osb    = ocfs2_get_inode_osb,
     .flags      = 0,
 };
 
 static struct ocfs2_lock_res_ops ocfs2_inode_inode_lops = {
     .get_osb    = ocfs2_get_inode_osb,
     .check_downconvert = ocfs2_check_meta_downconvert,
     .set_lvb    = ocfs2_set_meta_lvb,
     .downconvert_worker = ocfs2_data_convert_worker,
     .flags      = LOCK_TYPE_REQUIRES_REFRESH|LOCK_TYPE_USES_LVB,
 };
 
 static struct ocfs2_lock_res_ops ocfs2_super_lops = {
     .flags      = LOCK_TYPE_REQUIRES_REFRESH,
 };
 
 static struct ocfs2_lock_res_ops ocfs2_rename_lops = {
     .flags      = 0,
 };
 
 static struct ocfs2_lock_res_ops ocfs2_nfs_sync_lops = {
     .flags      = 0,
 };
 
 static struct ocfs2_lock_res_ops ocfs2_trim_fs_lops = {
     .flags      = LOCK_TYPE_REQUIRES_REFRESH|LOCK_TYPE_USES_LVB,
 };
 
 static struct ocfs2_lock_res_ops ocfs2_orphan_scan_lops = {
     .flags      = LOCK_TYPE_REQUIRES_REFRESH|LOCK_TYPE_USES_LVB,
 };
 
 static struct ocfs2_lock_res_ops ocfs2_dentry_lops = {
     .get_osb    = ocfs2_get_dentry_osb,
     .post_unlock    = ocfs2_dentry_post_unlock,
     .downconvert_worker = ocfs2_dentry_convert_worker,
     .flags      = 0,
 };
 
 static struct ocfs2_lock_res_ops ocfs2_inode_open_lops = {
     .get_osb    = ocfs2_get_inode_osb,
     .flags      = 0,
 };
 
 static struct ocfs2_lock_res_ops ocfs2_flock_lops = {
     .get_osb    = ocfs2_get_file_osb,
     .flags      = 0,
 };
 
 static struct ocfs2_lock_res_ops ocfs2_qinfo_lops = {
     .set_lvb    = ocfs2_set_qinfo_lvb,
     .get_osb    = ocfs2_get_qinfo_osb,
     .flags      = LOCK_TYPE_REQUIRES_REFRESH | LOCK_TYPE_USES_LVB,
 };
 
 static struct ocfs2_lock_res_ops ocfs2_refcount_block_lops = {
     .check_downconvert = ocfs2_check_refcount_downconvert,
     .downconvert_worker = ocfs2_refcount_convert_worker,
     .flags      = 0,
 };
 
 static inline int ocfs2_is_inode_lock(struct ocfs2_lock_res *lockres)
 {
     return lockres->l_type == OCFS2_LOCK_TYPE_META ||
         lockres->l_type == OCFS2_LOCK_TYPE_RW ||
         lockres->l_type == OCFS2_LOCK_TYPE_OPEN;
 }
 
 static inline struct ocfs2_lock_res *ocfs2_lksb_to_lock_res(struct ocfs2_dlm_lksb *lksb)
 {
     return container_of(lksb, struct ocfs2_lock_res, l_lksb);
 }
 
 static inline struct inode *ocfs2_lock_res_inode(struct ocfs2_lock_res *lockres)
 {
     BUG_ON(!ocfs2_is_inode_lock(lockres));
 
     return (struct inode *) lockres->l_priv;
 }
 
 static inline struct ocfs2_dentry_lock *ocfs2_lock_res_dl(struct ocfs2_lock_res *lockres)
 {
     BUG_ON(lockres->l_type != OCFS2_LOCK_TYPE_DENTRY);
 
     return (struct ocfs2_dentry_lock *)lockres->l_priv;
 }
 
 static inline struct ocfs2_mem_dqinfo *ocfs2_lock_res_qinfo(struct ocfs2_lock_res *lockres)
 {
     BUG_ON(lockres->l_type != OCFS2_LOCK_TYPE_QINFO);
 
     return (struct ocfs2_mem_dqinfo *)lockres->l_priv;
 }
 
 static inline struct ocfs2_refcount_tree *
 ocfs2_lock_res_refcount_tree(struct ocfs2_lock_res *res)
 {
     return container_of(res, struct ocfs2_refcount_tree, rf_lockres);
 }
 
 static inline struct ocfs2_super *ocfs2_get_lockres_osb(struct ocfs2_lock_res *lockres)
 {
     if (lockres->l_ops->get_osb)
         return lockres->l_ops->get_osb(lockres);
 
     return (struct ocfs2_super *)lockres->l_priv;
 }
 
 static int ocfs2_lock_create(struct ocfs2_super *osb,
                  struct ocfs2_lock_res *lockres,
                  int level,
                  u32 dlm_flags);
 static inline int ocfs2_may_continue_on_blocked_lock(struct ocfs2_lock_res *lockres,
                              int wanted);
 static void __ocfs2_cluster_unlock(struct ocfs2_super *osb,
                    struct ocfs2_lock_res *lockres,
                    int level, unsigned long caller_ip);
 static inline void ocfs2_cluster_unlock(struct ocfs2_super *osb,
                     struct ocfs2_lock_res *lockres,
                     int level)
 {
     __ocfs2_cluster_unlock(osb, lockres, level, _RET_IP_);
 }
 
 static inline void ocfs2_generic_handle_downconvert_action(struct ocfs2_lock_res *lockres);
 static inline void ocfs2_generic_handle_convert_action(struct ocfs2_lock_res *lockres);
 static inline void ocfs2_generic_handle_attach_action(struct ocfs2_lock_res *lockres);
 static int ocfs2_generic_handle_bast(struct ocfs2_lock_res *lockres, int level);
 static void ocfs2_schedule_blocked_lock(struct ocfs2_super *osb,
                     struct ocfs2_lock_res *lockres);
 static inline void ocfs2_recover_from_dlm_error(struct ocfs2_lock_res *lockres,
                         int convert);
 #define ocfs2_log_dlm_error(_func, _err, _lockres) do {                 \
     if ((_lockres)->l_type != OCFS2_LOCK_TYPE_DENTRY)               \
         mlog(ML_ERROR, "DLM error %d while calling %s on resource %s\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,
                        struct ocfs2_lock_res_ops *ops,
                        void *priv)
 {
     res->l_type          = type;
     res->l_ops           = ops;
     res->l_priv          = priv;
 
     res->l_level         = DLM_LOCK_IV;
     res->l_requested     = DLM_LOCK_IV;
     res->l_blocking      = DLM_LOCK_IV;
     res->l_action        = OCFS2_AST_INVALID;
     res->l_unlock_action = OCFS2_UNLOCK_INVALID;
 
     res->l_flags         = OCFS2_LOCK_INITIALIZED;
 
     ocfs2_add_lockres_tracking(res, osb->osb_dlm_debug);
 
     ocfs2_init_lock_stats(res);
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
     if (type != OCFS2_LOCK_TYPE_OPEN)
         lockdep_init_map(&res->l_lockdep_map, ocfs2_lock_type_strings[type],
                  &lockdep_keys[type], 0);
     else
         res->l_lockdep_map.key = NULL;
 #endif
 }
 
 void ocfs2_lock_res_init_once(struct ocfs2_lock_res *res)
 {
     /* This also clears out the lock status block */
     memset(res, 0, sizeof(struct ocfs2_lock_res));
     spin_lock_init(&res->l_lock);
     init_waitqueue_head(&res->l_event);
     INIT_LIST_HEAD(&res->l_blocked_list);
     INIT_LIST_HEAD(&res->l_mask_waiters);
     INIT_LIST_HEAD(&res->l_holders);
 }
 
 void ocfs2_inode_lock_res_init(struct ocfs2_lock_res *res,
                    enum ocfs2_lock_type type,
                    unsigned int generation,
                    struct inode *inode)
 {
     struct ocfs2_lock_res_ops *ops;
 
     switch(type) {
         case OCFS2_LOCK_TYPE_RW:
             ops = &ocfs2_inode_rw_lops;
             break;
         case OCFS2_LOCK_TYPE_META:
             ops = &ocfs2_inode_inode_lops;
             break;
         case OCFS2_LOCK_TYPE_OPEN:
             ops = &ocfs2_inode_open_lops;
             break;
         default:
             mlog_bug_on_msg(1, "type: %d\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 reques on seeing OCFS2_LOCK_UPCONVERT_FINISHING */
     kick_dc = (lockres->l_flags & OCFS2_LOCK_BLOCKED);
 
     spin_unlock_irqrestore(&lockres->l_lock, flags);
     if (kick_dc)
         ocfs2_wake_downconvert_thread(osb);
 out:
     /*
      * This is helping work around a lock inversion between the page lock
      * and dlm locks.  One path holds the page lock while calling aops
      * which block acquiring dlm locks.  The voting thread holds dlm
      * locks while acquiring page locks while down converting data locks.
      * This block is helping an aop path notice the inversion and back
      * off to unlock its page lock before trying the dlm lock again.
      */
     if (wait && arg_flags & OCFS2_LOCK_NONBLOCK &&
         mw.mw_mask & (OCFS2_LOCK_BUSY|OCFS2_LOCK_BLOCKED)) {
         wait = 0;
         spin_lock_irqsave(&lockres->l_lock, flags);
         if (__lockres_remove_mask_waiter(lockres, &mw)) {
             if (dlm_locked)
                 lockres_or_flags(lockres,
                     OCFS2_LOCK_NONBLOCK_FINISHED);
             spin_unlock_irqrestore(&lockres->l_lock, flags);
             ret = -EAGAIN;
         } else {
             spin_unlock_irqrestore(&lockres->l_lock, flags);
             goto again;
         }
     }
     if (wait) {
         ret = ocfs2_wait_for_mask(&mw);
         if (ret == 0)
             goto again;
         mlog_errno(ret);
     }
     ocfs2_update_lock_stats(lockres, level, &mw, ret);
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
     if (!ret && lockres->l_lockdep_map.key != NULL) {
         if (level == DLM_LOCK_PR)
             rwsem_acquire_read(&lockres->l_lockdep_map, l_subclass,
                 !!(arg_flags & OCFS2_META_LOCK_NOQUEUE),
                 caller_ip);
         else
             rwsem_acquire(&lockres->l_lockdep_map, l_subclass,
                 !!(arg_flags & OCFS2_META_LOCK_NOQUEUE),
                 caller_ip);
     }
 #endif
     return ret;
 }
 
 static inline int ocfs2_cluster_lock(struct ocfs2_super *osb,
                      struct ocfs2_lock_res *lockres,
                      int level,
                      u32 lkm_flags,
                      int arg_flags)
 {
     return __ocfs2_cluster_lock(osb, lockres, level, lkm_flags, arg_flags,
                     0, _RET_IP_);
 }
 
 
 static void __ocfs2_cluster_unlock(struct ocfs2_super *osb,
                    struct ocfs2_lock_res *lockres,
                    int level,
                    unsigned long caller_ip)
 {
     unsigned long flags;
 
     spin_lock_irqsave(&lockres->l_lock, flags);
     ocfs2_dec_holders(lockres, level);
     ocfs2_downconvert_on_unlock(osb, lockres);
     spin_unlock_irqrestore(&lockres->l_lock, flags);
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
     if (lockres->l_lockdep_map.key != NULL)
         rwsem_release(&lockres->l_lockdep_map, 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;
 
     lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
 
     /*
      * Invalidate the LVB of a deleted inode - this way other
      * nodes are forced to go to disk and discover the new inode
      * status.
      */
     if (oi->ip_flags & OCFS2_INODE_DELETED) {
         lvb->lvb_version = 0;
         goto out;
     }
 
     lvb->lvb_version   = OCFS2_LVB_VERSION;
     lvb->lvb_isize     = cpu_to_be64(i_size_read(inode));
     lvb->lvb_iclusters = cpu_to_be32(oi->ip_clusters);
     lvb->lvb_iuid      = cpu_to_be32(i_uid_read(inode));
     lvb->lvb_igid      = cpu_to_be32(i_gid_read(inode));
     lvb->lvb_imode     = cpu_to_be16(inode->i_mode);
     lvb->lvb_inlink    = cpu_to_be16(inode->i_nlink);
     lvb->lvb_iatime_packed  =
         cpu_to_be64(ocfs2_pack_timespec(&inode->i_atime));
     lvb->lvb_ictime_packed =
         cpu_to_be64(ocfs2_pack_timespec(&inode->i_ctime));
     lvb->lvb_imtime_packed =
         cpu_to_be64(ocfs2_pack_timespec(&inode->i_mtime));
     lvb->lvb_iattr    = cpu_to_be32(oi->ip_attr);
     lvb->lvb_idynfeatures = cpu_to_be16(oi->ip_dyn_features);
     lvb->lvb_igeneration = cpu_to_be32(inode->i_generation);
 
 out:
     mlog_meta_lvb(0, lockres);
 }
 
 static void ocfs2_unpack_timespec(struct 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;
 
     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(&inode->i_atime,
                   be64_to_cpu(lvb->lvb_iatime_packed));
     ocfs2_unpack_timespec(&inode->i_mtime,
                   be64_to_cpu(lvb->lvb_imtime_packed));
     ocfs2_unpack_timespec(&inode->i_ctime,
                   be64_to_cpu(lvb->lvb_ictime_packed));
     spin_unlock(&oi->ip_lock);
     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);
 }