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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
  * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/buffer_head.h>
 #include <linux/delay.h>
 #include <linux/sort.h>
 #include <linux/hash.h>
 #include <linux/jhash.h>
 #include <linux/kallsyms.h>
 #include <linux/gfs2_ondisk.h>
 #include <linux/list.h>
 #include <linux/wait.h>
 #include <linux/module.h>
 #include <linux/uaccess.h>
 #include <linux/seq_file.h>
 #include <linux/debugfs.h>
 #include <linux/kthread.h>
 #include <linux/freezer.h>
 #include <linux/workqueue.h>
 #include <linux/jiffies.h>
 #include <linux/rcupdate.h>
 #include <linux/rculist_bl.h>
 #include <linux/bit_spinlock.h>
 #include <linux/percpu.h>
 #include <linux/list_sort.h>
 #include <linux/lockref.h>
 #include <linux/rhashtable.h>
 
 #include "gfs2.h"
 #include "incore.h"
 #include "glock.h"
 #include "glops.h"
 #include "inode.h"
 #include "lops.h"
 #include "meta_io.h"
 #include "quota.h"
 #include "super.h"
 #include "util.h"
 #include "bmap.h"
 #define CREATE_TRACE_POINTS
 #include "trace_gfs2.h"
 
 struct gfs2_glock_iter {
     struct gfs2_sbd *sdp;       /* incore superblock           */
     struct rhashtable_iter hti; /* rhashtable iterator         */
     struct gfs2_glock *gl;      /* current glock struct        */
     loff_t last_pos;        /* last position               */
 };
 
 typedef void (*glock_examiner) (struct gfs2_glock * gl);
 
 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
 static void __gfs2_glock_dq(struct gfs2_holder *gh);
 
 static struct dentry *gfs2_root;
 static struct workqueue_struct *glock_workqueue;
 struct workqueue_struct *gfs2_delete_workqueue;
 static LIST_HEAD(lru_list);
 static atomic_t lru_count = ATOMIC_INIT(0);
 static DEFINE_SPINLOCK(lru_lock);
 
 #define GFS2_GL_HASH_SHIFT      15
 #define GFS2_GL_HASH_SIZE       BIT(GFS2_GL_HASH_SHIFT)
 
 static const struct rhashtable_params ht_parms = {
     .nelem_hint = GFS2_GL_HASH_SIZE * 3 / 4,
     .key_len = offsetofend(struct lm_lockname, ln_type),
     .key_offset = offsetof(struct gfs2_glock, gl_name),
     .head_offset = offsetof(struct gfs2_glock, gl_node),
 };
 
 static struct rhashtable gl_hash_table;
 
 #define GLOCK_WAIT_TABLE_BITS 12
 #define GLOCK_WAIT_TABLE_SIZE (1 << GLOCK_WAIT_TABLE_BITS)
 static wait_queue_head_t glock_wait_table[GLOCK_WAIT_TABLE_SIZE] __cacheline_aligned;
 
 struct wait_glock_queue {
     struct lm_lockname *name;
     wait_queue_entry_t wait;
 };
 
 static int glock_wake_function(wait_queue_entry_t *wait, unsigned int mode,
                    int sync, void *key)
 {
     struct wait_glock_queue *wait_glock =
         container_of(wait, struct wait_glock_queue, wait);
     struct lm_lockname *wait_name = wait_glock->name;
     struct lm_lockname *wake_name = key;
 
     if (wake_name->ln_sbd != wait_name->ln_sbd ||
         wake_name->ln_number != wait_name->ln_number ||
         wake_name->ln_type != wait_name->ln_type)
         return 0;
     return autoremove_wake_function(wait, mode, sync, key);
 }
 
 static wait_queue_head_t *glock_waitqueue(struct lm_lockname *name)
 {
     u32 hash = jhash2((u32 *)name, ht_parms.key_len / 4, 0);
 
     return glock_wait_table + hash_32(hash, GLOCK_WAIT_TABLE_BITS);
 }
 
 /**
  * wake_up_glock  -  Wake up waiters on a glock
  * @gl: the glock
  */
 static void wake_up_glock(struct gfs2_glock *gl)
 {
     wait_queue_head_t *wq = glock_waitqueue(&gl->gl_name);
 
     if (waitqueue_active(wq))
         __wake_up(wq, TASK_NORMAL, 1, &gl->gl_name);
 }
 
 static void gfs2_glock_dealloc(struct rcu_head *rcu)
 {
     struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
 
     kfree(gl->gl_lksb.sb_lvbptr);
     if (gl->gl_ops->go_flags & GLOF_ASPACE) {
         struct gfs2_glock_aspace *gla =
             container_of(gl, struct gfs2_glock_aspace, glock);
         kmem_cache_free(gfs2_glock_aspace_cachep, gla);
     } else
         kmem_cache_free(gfs2_glock_cachep, gl);
 }
 
 /**
  * glock_blocked_by_withdraw - determine if we can still use a glock
  * @gl: the glock
  *
  * We need to allow some glocks to be enqueued, dequeued, promoted, and demoted
  * when we're withdrawn. For example, to maintain metadata integrity, we should
  * disallow the use of inode and rgrp glocks when withdrawn. Other glocks, like
  * iopen or the transaction glocks may be safely used because none of their
  * metadata goes through the journal. So in general, we should disallow all
  * glocks that are journaled, and allow all the others. One exception is:
  * we need to allow our active journal to be promoted and demoted so others
  * may recover it and we can reacquire it when they're done.
  */
 static bool glock_blocked_by_withdraw(struct gfs2_glock *gl)
 {
     struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 
     if (likely(!gfs2_withdrawn(sdp)))
         return false;
     if (gl->gl_ops->go_flags & GLOF_NONDISK)
         return false;
     if (!sdp->sd_jdesc ||
         gl->gl_name.ln_number == sdp->sd_jdesc->jd_no_addr)
         return false;
     return true;
 }
 
 void gfs2_glock_free(struct gfs2_glock *gl)
 {
     struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 
     gfs2_glock_assert_withdraw(gl, atomic_read(&gl->gl_revokes) == 0);
     rhashtable_remove_fast(&gl_hash_table, &gl->gl_node, ht_parms);
     smp_mb();
     wake_up_glock(gl);
     call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
     if (atomic_dec_and_test(&sdp->sd_glock_disposal))
         wake_up(&sdp->sd_glock_wait);
 }
 
 /**
  * gfs2_glock_hold() - increment reference count on glock
  * @gl: The glock to hold
  *
  */
 
 void gfs2_glock_hold(struct gfs2_glock *gl)
 {
     GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
     lockref_get(&gl->gl_lockref);
 }
 
 /**
  * demote_ok - Check to see if it's ok to unlock a glock
  * @gl: the glock
  *
  * Returns: 1 if it's ok
  */
 
 static int demote_ok(const struct gfs2_glock *gl)
 {
     const struct gfs2_glock_operations *glops = gl->gl_ops;
 
     if (gl->gl_state == LM_ST_UNLOCKED)
         return 0;
     /*
      * Note that demote_ok is used for the lru process of disposing of
      * glocks. For this purpose, we don't care if the glock's holders
      * have the HIF_MAY_DEMOTE flag set or not. If someone is using
      * them, don't demote.
      */
     if (!list_empty(&gl->gl_holders))
         return 0;
     if (glops->go_demote_ok)
         return glops->go_demote_ok(gl);
     return 1;
 }
 
 
 void gfs2_glock_add_to_lru(struct gfs2_glock *gl)
 {
     if (!(gl->gl_ops->go_flags & GLOF_LRU))
         return;
 
     spin_lock(&lru_lock);
 
     list_move_tail(&gl->gl_lru, &lru_list);
 
     if (!test_bit(GLF_LRU, &gl->gl_flags)) {
         set_bit(GLF_LRU, &gl->gl_flags);
         atomic_inc(&lru_count);
     }
 
     spin_unlock(&lru_lock);
 }
 
 static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
 {
     if (!(gl->gl_ops->go_flags & GLOF_LRU))
         return;
 
     spin_lock(&lru_lock);
     if (test_bit(GLF_LRU, &gl->gl_flags)) {
         list_del_init(&gl->gl_lru);
         atomic_dec(&lru_count);
         clear_bit(GLF_LRU, &gl->gl_flags);
     }
     spin_unlock(&lru_lock);
 }
 
 /*
  * Enqueue the glock on the work queue.  Passes one glock reference on to the
  * work queue.
  */
 static void __gfs2_glock_queue_work(struct gfs2_glock *gl, unsigned long delay) {
     if (!queue_delayed_work(glock_workqueue, &gl->gl_work, delay)) {
         /*
          * We are holding the lockref spinlock, and the work was still
          * queued above.  The queued work (glock_work_func) takes that
          * spinlock before dropping its glock reference(s), so it
          * cannot have dropped them in the meantime.
          */
         GLOCK_BUG_ON(gl, gl->gl_lockref.count < 2);
         gl->gl_lockref.count--;
     }
 }
 
 static void gfs2_glock_queue_work(struct gfs2_glock *gl, unsigned long delay) {
     spin_lock(&gl->gl_lockref.lock);
     __gfs2_glock_queue_work(gl, delay);
     spin_unlock(&gl->gl_lockref.lock);
 }
 
 static void __gfs2_glock_put(struct gfs2_glock *gl)
 {
     struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
     struct address_space *mapping = gfs2_glock2aspace(gl);
 
     lockref_mark_dead(&gl->gl_lockref);
 
     gfs2_glock_remove_from_lru(gl);
     spin_unlock(&gl->gl_lockref.lock);
     GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
     if (mapping) {
         truncate_inode_pages_final(mapping);
         if (!gfs2_withdrawn(sdp))
             GLOCK_BUG_ON(gl, !mapping_empty(mapping));
     }
     trace_gfs2_glock_put(gl);
     sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
 }
 
 /*
  * Cause the glock to be put in work queue context.
  */
 void gfs2_glock_queue_put(struct gfs2_glock *gl)
 {
     gfs2_glock_queue_work(gl, 0);
 }
 
 /**
  * gfs2_glock_put() - Decrement reference count on glock
  * @gl: The glock to put
  *
  */
 
 void gfs2_glock_put(struct gfs2_glock *gl)
 {
     if (lockref_put_or_lock(&gl->gl_lockref))
         return;
 
     __gfs2_glock_put(gl);
 }
 
 /**
  * may_grant - check if it's ok to grant a new lock
  * @gl: The glock
  * @current_gh: One of the current holders of @gl
  * @gh: The lock request which we wish to grant
  *
  * With our current compatibility rules, if a glock has one or more active
  * holders (HIF_HOLDER flag set), any of those holders can be passed in as
  * @current_gh; they are all the same as far as compatibility with the new @gh
  * goes.
  *
  * Returns true if it's ok to grant the lock.
  */
 
 static inline bool may_grant(struct gfs2_glock *gl,
                  struct gfs2_holder *current_gh,
                  struct gfs2_holder *gh)
 {
     if (current_gh) {
         GLOCK_BUG_ON(gl, !test_bit(HIF_HOLDER, &current_gh->gh_iflags));
 
         switch(current_gh->gh_state) {
         case LM_ST_EXCLUSIVE:
             /*
              * Here we make a special exception to grant holders
              * who agree to share the EX lock with other holders
              * who also have the bit set. If the original holder
              * has the LM_FLAG_NODE_SCOPE bit set, we grant more
              * holders with the bit set.
              */
             return gh->gh_state == LM_ST_EXCLUSIVE &&
                    (current_gh->gh_flags & LM_FLAG_NODE_SCOPE) &&
                    (gh->gh_flags & LM_FLAG_NODE_SCOPE);
 
         case LM_ST_SHARED:
         case LM_ST_DEFERRED:
             return gh->gh_state == current_gh->gh_state;
 
         default:
             return false;
         }
     }
 
     if (gl->gl_state == gh->gh_state)
         return true;
     if (gh->gh_flags & GL_EXACT)
         return false;
     if (gl->gl_state == LM_ST_EXCLUSIVE) {
         return gh->gh_state == LM_ST_SHARED ||
                gh->gh_state == LM_ST_DEFERRED;
     }
     if (gh->gh_flags & LM_FLAG_ANY)
         return gl->gl_state != LM_ST_UNLOCKED;
     return false;
 }
 
 static void gfs2_holder_wake(struct gfs2_holder *gh)
 {
     clear_bit(HIF_WAIT, &gh->gh_iflags);
     smp_mb__after_atomic();
     wake_up_bit(&gh->gh_iflags, HIF_WAIT);
     if (gh->gh_flags & GL_ASYNC) {
         struct gfs2_sbd *sdp = gh->gh_gl->gl_name.ln_sbd;
 
         wake_up(&sdp->sd_async_glock_wait);
     }
 }
 
 /**
  * do_error - Something unexpected has happened during a lock request
  * @gl: The glock
  * @ret: The status from the DLM
  */
 
 static void do_error(struct gfs2_glock *gl, const int ret)
 {
     struct gfs2_holder *gh, *tmp;
 
     list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
         if (!test_bit(HIF_WAIT, &gh->gh_iflags))
             continue;
         if (ret & LM_OUT_ERROR)
             gh->gh_error = -EIO;
         else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
             gh->gh_error = GLR_TRYFAILED;
         else
             continue;
         list_del_init(&gh->gh_list);
         trace_gfs2_glock_queue(gh, 0);
         gfs2_holder_wake(gh);
     }
 }
 
 /**
  * demote_incompat_holders - demote incompatible demoteable holders
  * @gl: the glock we want to promote
  * @current_gh: the newly promoted holder
  *
  * We're passing the newly promoted holder in @current_gh, but actually, any of
  * the strong holders would do.
  */
 static void demote_incompat_holders(struct gfs2_glock *gl,
                     struct gfs2_holder *current_gh)
 {
     struct gfs2_holder *gh, *tmp;
 
     /*
      * Demote incompatible holders before we make ourselves eligible.
      * (This holder may or may not allow auto-demoting, but we don't want
      * to demote the new holder before it's even granted.)
      */
     list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
         /*
          * Since holders are at the front of the list, we stop when we
          * find the first non-holder.
          */
         if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
             return;
         if (gh == current_gh)
             continue;
         if (test_bit(HIF_MAY_DEMOTE, &gh->gh_iflags) &&
             !may_grant(gl, current_gh, gh)) {
             /*
              * We should not recurse into do_promote because
              * __gfs2_glock_dq only calls handle_callback,
              * gfs2_glock_add_to_lru and __gfs2_glock_queue_work.
              */
             __gfs2_glock_dq(gh);
         }
     }
 }
 
 /**
  * find_first_holder - find the first "holder" gh
  * @gl: the glock
  */
 
 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 {
     struct gfs2_holder *gh;
 
     if (!list_empty(&gl->gl_holders)) {
         gh = list_first_entry(&gl->gl_holders, struct gfs2_holder,
                       gh_list);
         if (test_bit(HIF_HOLDER, &gh->gh_iflags))
             return gh;
     }
     return NULL;
 }
 
 /**
  * find_first_strong_holder - find the first non-demoteable holder
  * @gl: the glock
  *
  * Find the first holder that doesn't have the HIF_MAY_DEMOTE flag set.
  */
 static inline struct gfs2_holder *
 find_first_strong_holder(struct gfs2_glock *gl)
 {
     struct gfs2_holder *gh;
 
     list_for_each_entry(gh, &gl->gl_holders, gh_list) {
         if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
             return NULL;
         if (!test_bit(HIF_MAY_DEMOTE, &gh->gh_iflags))
             return gh;
     }
     return NULL;
 }
 
 /*
  * gfs2_instantiate - Call the glops instantiate function
  * @gh: The glock holder
  *
  * Returns: 0 if instantiate was successful, or error.
  */
 int gfs2_instantiate(struct gfs2_holder *gh)
 {
     struct gfs2_glock *gl = gh->gh_gl;
     const struct gfs2_glock_operations *glops = gl->gl_ops;
     int ret;
 
 again:
     if (!test_bit(GLF_INSTANTIATE_NEEDED, &gl->gl_flags))
         goto done;
 
     /*
      * Since we unlock the lockref lock, we set a flag to indicate
      * instantiate is in progress.
      */
     if (test_and_set_bit(GLF_INSTANTIATE_IN_PROG, &gl->gl_flags)) {
         wait_on_bit(&gl->gl_flags, GLF_INSTANTIATE_IN_PROG,
                 TASK_UNINTERRUPTIBLE);
         /*
          * Here we just waited for a different instantiate to finish.
          * But that may not have been successful, as when a process
          * locks an inode glock _before_ it has an actual inode to
          * instantiate into. So we check again. This process might
          * have an inode to instantiate, so might be successful.
          */
         goto again;
     }
 
     ret = glops->go_instantiate(gl);
     if (!ret)
         clear_bit(GLF_INSTANTIATE_NEEDED, &gl->gl_flags);
     clear_and_wake_up_bit(GLF_INSTANTIATE_IN_PROG, &gl->gl_flags);
     if (ret)
         return ret;
 
 done:
     if (glops->go_held)
         return glops->go_held(gh);
     return 0;
 }
 
 /**
  * do_promote - promote as many requests as possible on the current queue
  * @gl: The glock
  * 
  * Returns: 1 if there is a blocked holder at the head of the list
  */
 
 static int do_promote(struct gfs2_glock *gl)
 {
     struct gfs2_holder *gh, *current_gh;
     bool incompat_holders_demoted = false;
 
     current_gh = find_first_strong_holder(gl);
     list_for_each_entry(gh, &gl->gl_holders, gh_list) {
         if (test_bit(HIF_HOLDER, &gh->gh_iflags))
             continue;
         if (!may_grant(gl, current_gh, gh)) {
             /*
              * If we get here, it means we may not grant this
              * holder for some reason. If this holder is at the
              * head of the list, it means we have a blocked holder
              * at the head, so return 1.
              */
             if (list_is_first(&gh->gh_list, &gl->gl_holders))
                 return 1;
             do_error(gl, 0);
             break;
         }
         set_bit(HIF_HOLDER, &gh->gh_iflags);
         trace_gfs2_promote(gh);
         gfs2_holder_wake(gh);
         if (!incompat_holders_demoted) {
             current_gh = gh;
             demote_incompat_holders(gl, current_gh);
             incompat_holders_demoted = true;
         }
     }
     return 0;
 }
 
 /**
  * find_first_waiter - find the first gh that's waiting for the glock
  * @gl: the glock
  */
 
 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
 {
     struct gfs2_holder *gh;
 
     list_for_each_entry(gh, &gl->gl_holders, gh_list) {
         if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
             return gh;
     }
     return NULL;
 }
 
 /**
  * state_change - record that the glock is now in a different state
  * @gl: the glock
  * @new_state: the new state
  */
 
 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 {
     int held1, held2;
 
     held1 = (gl->gl_state != LM_ST_UNLOCKED);
     held2 = (new_state != LM_ST_UNLOCKED);
 
     if (held1 != held2) {
         GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
         if (held2)
             gl->gl_lockref.count++;
         else
             gl->gl_lockref.count--;
     }
     if (new_state != gl->gl_target)
         /* shorten our minimum hold time */
         gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
                        GL_GLOCK_MIN_HOLD);
     gl->gl_state = new_state;
     gl->gl_tchange = jiffies;
 }
 
 static void gfs2_set_demote(struct gfs2_glock *gl)
 {
     struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 
     set_bit(GLF_DEMOTE, &gl->gl_flags);
     smp_mb();
     wake_up(&sdp->sd_async_glock_wait);
 }
 
 static void gfs2_demote_wake(struct gfs2_glock *gl)
 {
     gl->gl_demote_state = LM_ST_EXCLUSIVE;
     clear_bit(GLF_DEMOTE, &gl->gl_flags);
     smp_mb__after_atomic();
     wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
 }
 
 /**
  * finish_xmote - The DLM has replied to one of our lock requests
  * @gl: The glock
  * @ret: The status from the DLM
  *
  */
 
 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 {
     const struct gfs2_glock_operations *glops = gl->gl_ops;
     struct gfs2_holder *gh;
     unsigned state = ret & LM_OUT_ST_MASK;
 
     spin_lock(&gl->gl_lockref.lock);
     trace_gfs2_glock_state_change(gl, state);
     state_change(gl, state);
     gh = find_first_waiter(gl);
 
     /* Demote to UN request arrived during demote to SH or DF */
     if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
         state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
         gl->gl_target = LM_ST_UNLOCKED;
 
     /* Check for state != intended state */
     if (unlikely(state != gl->gl_target)) {
         if (gh && (ret & LM_OUT_CANCELED))
             gfs2_holder_wake(gh);
         if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
             /* move to back of queue and try next entry */
             if (ret & LM_OUT_CANCELED) {
                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
                     list_move_tail(&gh->gh_list, &gl->gl_holders);
                 gh = find_first_waiter(gl);
                 gl->gl_target = gh->gh_state;
                 goto retry;
             }
             /* Some error or failed "try lock" - report it */
             if ((ret & LM_OUT_ERROR) ||
                 (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
                 gl->gl_target = gl->gl_state;
                 do_error(gl, ret);
                 goto out;
             }
         }
         switch(state) {
         /* Unlocked due to conversion deadlock, try again */
         case LM_ST_UNLOCKED:
 retry:
             do_xmote(gl, gh, gl->gl_target);
             break;
         /* Conversion fails, unlock and try again */
         case LM_ST_SHARED:
         case LM_ST_DEFERRED:
             do_xmote(gl, gh, LM_ST_UNLOCKED);
             break;
         default: /* Everything else */
             fs_err(gl->gl_name.ln_sbd, "wanted %u got %u\n",
                    gl->gl_target, state);
             GLOCK_BUG_ON(gl, 1);
         }
         spin_unlock(&gl->gl_lockref.lock);
         return;
     }
 
     /* Fast path - we got what we asked for */
     if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
         gfs2_demote_wake(gl);
     if (state != LM_ST_UNLOCKED) {
         if (glops->go_xmote_bh) {
             int rv;
 
             spin_unlock(&gl->gl_lockref.lock);
             rv = glops->go_xmote_bh(gl);
             spin_lock(&gl->gl_lockref.lock);
             if (rv) {
                 do_error(gl, rv);
                 goto out;
             }
         }
         do_promote(gl);
     }
 out:
     clear_bit(GLF_LOCK, &gl->gl_flags);
     spin_unlock(&gl->gl_lockref.lock);
 }
 
 static bool is_system_glock(struct gfs2_glock *gl)
 {
     struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
     struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 
     if (gl == m_ip->i_gl)
         return true;
     return false;
 }
 
 /**
  * do_xmote - Calls the DLM to change the state of a lock
  * @gl: The lock state
  * @gh: The holder (only for promotes)
  * @target: The target lock state
  *
  */
 
 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
 __releases(&gl->gl_lockref.lock)
 __acquires(&gl->gl_lockref.lock)
 {
     const struct gfs2_glock_operations *glops = gl->gl_ops;
     struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
     unsigned int lck_flags = (unsigned int)(gh ? gh->gh_flags : 0);
     int ret;
 
     if (target != LM_ST_UNLOCKED && glock_blocked_by_withdraw(gl) &&
         gh && !(gh->gh_flags & LM_FLAG_NOEXP))
         return;
     lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
               LM_FLAG_PRIORITY);
     GLOCK_BUG_ON(gl, gl->gl_state == target);
     GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
     if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
         glops->go_inval) {
         /*
          * If another process is already doing the invalidate, let that
          * finish first.  The glock state machine will get back to this
          * holder again later.
          */
         if (test_and_set_bit(GLF_INVALIDATE_IN_PROGRESS,
                      &gl->gl_flags))
             return;
         do_error(gl, 0); /* Fail queued try locks */
     }
     gl->gl_req = target;
     set_bit(GLF_BLOCKING, &gl->gl_flags);
     if ((gl->gl_req == LM_ST_UNLOCKED) ||
         (gl->gl_state == LM_ST_EXCLUSIVE) ||
         (lck_flags & (LM_FLAG_TRY|LM_FLAG_TRY_1CB)))
         clear_bit(GLF_BLOCKING, &gl->gl_flags);
     spin_unlock(&gl->gl_lockref.lock);
     if (glops->go_sync) {
         ret = glops->go_sync(gl);
         /* If we had a problem syncing (due to io errors or whatever,
          * we should not invalidate the metadata or tell dlm to
          * release the glock to other nodes.
          */
         if (ret) {
             if (cmpxchg(&sdp->sd_log_error, 0, ret)) {
                 fs_err(sdp, "Error %d syncing glock \n", ret);
                 gfs2_dump_glock(NULL, gl, true);
             }
             goto skip_inval;
         }
     }
     if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags)) {
         /*
          * The call to go_sync should have cleared out the ail list.
          * If there are still items, we have a problem. We ought to
          * withdraw, but we can't because the withdraw code also uses
          * glocks. Warn about the error, dump the glock, then fall
          * through and wait for logd to do the withdraw for us.
          */
         if ((atomic_read(&gl->gl_ail_count) != 0) &&
             (!cmpxchg(&sdp->sd_log_error, 0, -EIO))) {
             gfs2_glock_assert_warn(gl,
                            !atomic_read(&gl->gl_ail_count));
             gfs2_dump_glock(NULL, gl, true);
         }
         glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
     }
 
 skip_inval:
     gfs2_glock_hold(gl);
     /*
      * Check for an error encountered since we called go_sync and go_inval.
      * If so, we can't withdraw from the glock code because the withdraw
      * code itself uses glocks (see function signal_our_withdraw) to
      * change the mount to read-only. Most importantly, we must not call
      * dlm to unlock the glock until the journal is in a known good state
      * (after journal replay) otherwise other nodes may use the object
      * (rgrp or dinode) and then later, journal replay will corrupt the
      * file system. The best we can do here is wait for the logd daemon
      * to see sd_log_error and withdraw, and in the meantime, requeue the
      * work for later.
      *
      * We make a special exception for some system glocks, such as the
      * system statfs inode glock, which needs to be granted before the
      * gfs2_quotad daemon can exit, and that exit needs to finish before
      * we can unmount the withdrawn file system.
      *
      * However, if we're just unlocking the lock (say, for unmount, when
      * gfs2_gl_hash_clear calls clear_glock) and recovery is complete
      * then it's okay to tell dlm to unlock it.
      */
     if (unlikely(sdp->sd_log_error && !gfs2_withdrawn(sdp)))
         gfs2_withdraw_delayed(sdp);
     if (glock_blocked_by_withdraw(gl) &&
         (target != LM_ST_UNLOCKED ||
          test_bit(SDF_WITHDRAW_RECOVERY, &sdp->sd_flags))) {
         if (!is_system_glock(gl)) {
             gfs2_glock_queue_work(gl, GL_GLOCK_DFT_HOLD);
             goto out;
         } else {
             clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
         }
     }
 
     if (sdp->sd_lockstruct.ls_ops->lm_lock) {
         /* lock_dlm */
         ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
         if (ret == -EINVAL && gl->gl_target == LM_ST_UNLOCKED &&
             target == LM_ST_UNLOCKED &&
             test_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags)) {
             finish_xmote(gl, target);
             gfs2_glock_queue_work(gl, 0);
         } else if (ret) {
             fs_err(sdp, "lm_lock ret %d\n", ret);
             GLOCK_BUG_ON(gl, !gfs2_withdrawn(sdp));
         }
     } else { /* lock_nolock */
         finish_xmote(gl, target);
         gfs2_glock_queue_work(gl, 0);
     }
 out:
     spin_lock(&gl->gl_lockref.lock);
 }
 
 /**
  * run_queue - do all outstanding tasks related to a glock
  * @gl: The glock in question
  * @nonblock: True if we must not block in run_queue
  *
  */
 
 static void run_queue(struct gfs2_glock *gl, const int nonblock)
 __releases(&gl->gl_lockref.lock)
 __acquires(&gl->gl_lockref.lock)
 {
     struct gfs2_holder *gh = NULL;
 
     if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
         return;
 
     GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
 
     if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
         gl->gl_demote_state != gl->gl_state) {
         if (find_first_holder(gl))
             goto out_unlock;
         if (nonblock)
             goto out_sched;
         set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
         GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
         gl->gl_target = gl->gl_demote_state;
     } else {
         if (test_bit(GLF_DEMOTE, &gl->gl_flags))
             gfs2_demote_wake(gl);
         if (do_promote(gl) == 0)
             goto out_unlock;
         gh = find_first_waiter(gl);
         gl->gl_target = gh->gh_state;
         if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
             do_error(gl, 0); /* Fail queued try locks */
     }
     do_xmote(gl, gh, gl->gl_target);
     return;
 
 out_sched:
     clear_bit(GLF_LOCK, &gl->gl_flags);
     smp_mb__after_atomic();
     gl->gl_lockref.count++;
     __gfs2_glock_queue_work(gl, 0);
     return;
 
 out_unlock:
     clear_bit(GLF_LOCK, &gl->gl_flags);
     smp_mb__after_atomic();
     return;
 }
 
 void gfs2_inode_remember_delete(struct gfs2_glock *gl, u64 generation)
 {
     struct gfs2_inode_lvb *ri = (void *)gl->gl_lksb.sb_lvbptr;
 
     if (ri->ri_magic == 0)
         ri->ri_magic = cpu_to_be32(GFS2_MAGIC);
     if (ri->ri_magic == cpu_to_be32(GFS2_MAGIC))
         ri->ri_generation_deleted = cpu_to_be64(generation);
 }
 
 bool gfs2_inode_already_deleted(struct gfs2_glock *gl, u64 generation)
 {
     struct gfs2_inode_lvb *ri = (void *)gl->gl_lksb.sb_lvbptr;
 
     if (ri->ri_magic != cpu_to_be32(GFS2_MAGIC))
         return false;
     return generation <= be64_to_cpu(ri->ri_generation_deleted);
 }
 
 static void gfs2_glock_poke(struct gfs2_glock *gl)
 {
     int flags = LM_FLAG_TRY_1CB | LM_FLAG_ANY | GL_SKIP;
     struct gfs2_holder gh;
     int error;
 
     __gfs2_holder_init(gl, LM_ST_SHARED, flags, &gh, _RET_IP_);
     error = gfs2_glock_nq(&gh);
     if (!error)
         gfs2_glock_dq(&gh);
     gfs2_holder_uninit(&gh);
 }
 
 static bool gfs2_try_evict(struct gfs2_glock *gl)
 {
     struct gfs2_inode *ip;
     bool evicted = false;
 
     /*
      * If there is contention on the iopen glock and we have an inode, try
      * to grab and release the inode so that it can be evicted.  This will
      * allow the remote node to go ahead and delete the inode without us
      * having to do it, which will avoid rgrp glock thrashing.
      *
      * The remote node is likely still holding the corresponding inode
      * glock, so it will run before we get to verify that the delete has
      * happened below.
      */
     spin_lock(&gl->gl_lockref.lock);
     ip = gl->gl_object;
     if (ip && !igrab(&ip->i_inode))
         ip = NULL;
     spin_unlock(&gl->gl_lockref.lock);
     if (ip) {
         struct gfs2_glock *inode_gl = NULL;
 
         gl->gl_no_formal_ino = ip->i_no_formal_ino;
         set_bit(GIF_DEFERRED_DELETE, &ip->i_flags);
         d_prune_aliases(&ip->i_inode);
         iput(&ip->i_inode);
 
         /* If the inode was evicted, gl->gl_object will now be NULL. */
         spin_lock(&gl->gl_lockref.lock);
         ip = gl->gl_object;
         if (ip) {
             inode_gl = ip->i_gl;
             lockref_get(&inode_gl->gl_lockref);
             clear_bit(GIF_DEFERRED_DELETE, &ip->i_flags);
         }
         spin_unlock(&gl->gl_lockref.lock);
         if (inode_gl) {
             gfs2_glock_poke(inode_gl);
             gfs2_glock_put(inode_gl);
         }
         evicted = !ip;
     }
     return evicted;
 }
 
 static void delete_work_func(struct work_struct *work)
 {
     struct delayed_work *dwork = to_delayed_work(work);
     struct gfs2_glock *gl = container_of(dwork, struct gfs2_glock, gl_delete);
     struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
     struct inode *inode;
     u64 no_addr = gl->gl_name.ln_number;
 
     spin_lock(&gl->gl_lockref.lock);
     clear_bit(GLF_PENDING_DELETE, &gl->gl_flags);
     spin_unlock(&gl->gl_lockref.lock);
 
     if (test_bit(GLF_DEMOTE, &gl->gl_flags)) {
         /*
          * If we can evict the inode, give the remote node trying to
          * delete the inode some time before verifying that the delete
          * has happened.  Otherwise, if we cause contention on the inode glock
          * immediately, the remote node will think that we still have
          * the inode in use, and so it will give up waiting.
          *
          * If we can't evict the inode, signal to the remote node that
          * the inode is still in use.  We'll later try to delete the
          * inode locally in gfs2_evict_inode.
          *
          * FIXME: We only need to verify that the remote node has
          * deleted the inode because nodes before this remote delete
          * rework won't cooperate.  At a later time, when we no longer
          * care about compatibility with such nodes, we can skip this
          * step entirely.
          */
         if (gfs2_try_evict(gl)) {
             if (gfs2_queue_delete_work(gl, 5 * HZ))
                 return;
         }
         goto out;
     }
 
     inode = gfs2_lookup_by_inum(sdp, no_addr, gl->gl_no_formal_ino,
                     GFS2_BLKST_UNLINKED);
     if (!IS_ERR_OR_NULL(inode)) {
         d_prune_aliases(inode);
         iput(inode);
     }
 out:
     gfs2_glock_put(gl);
 }
 
 static void glock_work_func(struct work_struct *work)
 {
     unsigned long delay = 0;
     struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
     unsigned int drop_refs = 1;
 
     if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
         finish_xmote(gl, gl->gl_reply);
         drop_refs++;
     }
     spin_lock(&gl->gl_lockref.lock);
     if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
         gl->gl_state != LM_ST_UNLOCKED &&
         gl->gl_demote_state != LM_ST_EXCLUSIVE) {
         unsigned long holdtime, now = jiffies;
 
         holdtime = gl->gl_tchange + gl->gl_hold_time;
         if (time_before(now, holdtime))
             delay = holdtime - now;
 
         if (!delay) {
             clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
             gfs2_set_demote(gl);
         }
     }
     run_queue(gl, 0);
     if (delay) {
         /* Keep one glock reference for the work we requeue. */
         drop_refs--;
         if (gl->gl_name.ln_type != LM_TYPE_INODE)
             delay = 0;
         __gfs2_glock_queue_work(gl, delay);
     }
 
     /*
      * Drop the remaining glock references manually here. (Mind that
      * __gfs2_glock_queue_work depends on the lockref spinlock begin held
      * here as well.)
      */
     gl->gl_lockref.count -= drop_refs;
     if (!gl->gl_lockref.count) {
         __gfs2_glock_put(gl);
         return;
     }
     spin_unlock(&gl->gl_lockref.lock);
 }
 
 static struct gfs2_glock *find_insert_glock(struct lm_lockname *name,
                         struct gfs2_glock *new)
 {
     struct wait_glock_queue wait;
     wait_queue_head_t *wq = glock_waitqueue(name);
     struct gfs2_glock *gl;
 
     wait.name = name;
     init_wait(&wait.wait);
     wait.wait.func = glock_wake_function;
 
 again:
     prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
     rcu_read_lock();
     if (new) {
         gl = rhashtable_lookup_get_insert_fast(&gl_hash_table,
             &new->gl_node, ht_parms);
         if (IS_ERR(gl))
             goto out;
     } else {
         gl = rhashtable_lookup_fast(&gl_hash_table,
             name, ht_parms);
     }
     if (gl && !lockref_get_not_dead(&gl->gl_lockref)) {
         rcu_read_unlock();
         schedule();
         goto again;
     }
 out:
     rcu_read_unlock();
     finish_wait(wq, &wait.wait);
     return gl;
 }
 
 /**
  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
  * @sdp: The GFS2 superblock
  * @number: the lock number
  * @glops: The glock_operations to use
  * @create: If 0, don't create the glock if it doesn't exist
  * @glp: the glock is returned here
  *
  * This does not lock a glock, just finds/creates structures for one.
  *
  * Returns: errno
  */
 
 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
            const struct gfs2_glock_operations *glops, int create,
            struct gfs2_glock **glp)
 {
     struct super_block *s = sdp->sd_vfs;
     struct lm_lockname name = { .ln_number = number,
                     .ln_type = glops->go_type,
                     .ln_sbd = sdp };
     struct gfs2_glock *gl, *tmp;
     struct address_space *mapping;
     int ret = 0;
 
     gl = find_insert_glock(&name, NULL);
     if (gl) {
         *glp = gl;
         return 0;
     }
     if (!create)
         return -ENOENT;
 
     if (glops->go_flags & GLOF_ASPACE) {
         struct gfs2_glock_aspace *gla =
             kmem_cache_alloc(gfs2_glock_aspace_cachep, GFP_NOFS);
         if (!gla)
             return -ENOMEM;
         gl = &gla->glock;
     } else {
         gl = kmem_cache_alloc(gfs2_glock_cachep, GFP_NOFS);
         if (!gl)
             return -ENOMEM;
     }
     memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
     gl->gl_ops = glops;
 
     if (glops->go_flags & GLOF_LVB) {
         gl->gl_lksb.sb_lvbptr = kzalloc(GDLM_LVB_SIZE, GFP_NOFS);
         if (!gl->gl_lksb.sb_lvbptr) {
             gfs2_glock_dealloc(&gl->gl_rcu);
             return -ENOMEM;
         }
     }
 
     atomic_inc(&sdp->sd_glock_disposal);
     gl->gl_node.next = NULL;
     gl->gl_flags = glops->go_instantiate ? BIT(GLF_INSTANTIATE_NEEDED) : 0;
     gl->gl_name = name;
     lockdep_set_subclass(&gl->gl_lockref.lock, glops->go_subclass);
     gl->gl_lockref.count = 1;
     gl->gl_state = LM_ST_UNLOCKED;
     gl->gl_target = LM_ST_UNLOCKED;
     gl->gl_demote_state = LM_ST_EXCLUSIVE;
     gl->gl_dstamp = 0;
     preempt_disable();
     /* We use the global stats to estimate the initial per-glock stats */
     gl->gl_stats = this_cpu_ptr(sdp->sd_lkstats)->lkstats[glops->go_type];
     preempt_enable();
     gl->gl_stats.stats[GFS2_LKS_DCOUNT] = 0;
     gl->gl_stats.stats[GFS2_LKS_QCOUNT] = 0;
     gl->gl_tchange = jiffies;
     gl->gl_object = NULL;
     gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
     INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
     if (gl->gl_name.ln_type == LM_TYPE_IOPEN)
         INIT_DELAYED_WORK(&gl->gl_delete, delete_work_func);
 
     mapping = gfs2_glock2aspace(gl);
     if (mapping) {
                 mapping->a_ops = &gfs2_meta_aops;
         mapping->host = s->s_bdev->bd_inode;
         mapping->flags = 0;
         mapping_set_gfp_mask(mapping, GFP_NOFS);
         mapping->private_data = NULL;
         mapping->writeback_index = 0;
     }
 
     tmp = find_insert_glock(&name, gl);
     if (!tmp) {
         *glp = gl;
         goto out;
     }
     if (IS_ERR(tmp)) {
         ret = PTR_ERR(tmp);
         goto out_free;
     }
     *glp = tmp;
 
 out_free:
     gfs2_glock_dealloc(&gl->gl_rcu);
     if (atomic_dec_and_test(&sdp->sd_glock_disposal))
         wake_up(&sdp->sd_glock_wait);
 
 out:
     return ret;
 }
 
 /**
  * __gfs2_holder_init - initialize a struct gfs2_holder in the default way
  * @gl: the glock
  * @state: the state we're requesting
  * @flags: the modifier flags
  * @gh: the holder structure
  *
  */
 
 void __gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, u16 flags,
             struct gfs2_holder *gh, unsigned long ip)
 {
     INIT_LIST_HEAD(&gh->gh_list);
     gh->gh_gl = gl;
     gh->gh_ip = ip;
     gh->gh_owner_pid = get_pid(task_pid(current));
     gh->gh_state = state;
     gh->gh_flags = flags;
     gh->gh_iflags = 0;
     gfs2_glock_hold(gl);
 }
 
 /**
  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
  * @state: the state we're requesting
  * @flags: the modifier flags
  * @gh: the holder structure
  *
  * Don't mess with the glock.
  *
  */
 
 void gfs2_holder_reinit(unsigned int state, u16 flags, struct gfs2_holder *gh)
 {
     gh->gh_state = state;
     gh->gh_flags = flags;
     gh->gh_iflags = 0;
     gh->gh_ip = _RET_IP_;
     put_pid(gh->gh_owner_pid);
     gh->gh_owner_pid = get_pid(task_pid(current));
 }
 
 /**
  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
  * @gh: the holder structure
  *
  */
 
 void gfs2_holder_uninit(struct gfs2_holder *gh)
 {
     put_pid(gh->gh_owner_pid);
     gfs2_glock_put(gh->gh_gl);
     gfs2_holder_mark_uninitialized(gh);
     gh->gh_ip = 0;
 }
 
 static void gfs2_glock_update_hold_time(struct gfs2_glock *gl,
                     unsigned long start_time)
 {
     /* Have we waited longer that a second? */
     if (time_after(jiffies, start_time + HZ)) {
         /* Lengthen the minimum hold time. */
         gl->gl_hold_time = min(gl->gl_hold_time + GL_GLOCK_HOLD_INCR,
                        GL_GLOCK_MAX_HOLD);
     }
 }
 
 /**
  * gfs2_glock_holder_ready - holder is ready and its error code can be collected
  * @gh: the glock holder
  *
  * Called when a glock holder no longer needs to be waited for because it is
  * now either held (HIF_HOLDER set; gh_error == 0), or acquiring the lock has
  * failed (gh_error != 0).
  */
 
 int gfs2_glock_holder_ready(struct gfs2_holder *gh)
 {
     if (gh->gh_error || (gh->gh_flags & GL_SKIP))
         return gh->gh_error;
     gh->gh_error = gfs2_instantiate(gh);
     if (gh->gh_error)
         gfs2_glock_dq(gh);
     return gh->gh_error;
 }
 
 /**
  * gfs2_glock_wait - wait on a glock acquisition
  * @gh: the glock holder
  *
  * Returns: 0 on success
  */
 
 int gfs2_glock_wait(struct gfs2_holder *gh)
 {
     unsigned long start_time = jiffies;
 
     might_sleep();
     wait_on_bit(&gh->gh_iflags, HIF_WAIT, TASK_UNINTERRUPTIBLE);
     gfs2_glock_update_hold_time(gh->gh_gl, start_time);
     return gfs2_glock_holder_ready(gh);
 }
 
 static int glocks_pending(unsigned int num_gh, struct gfs2_holder *ghs)
 {
     int i;
 
     for (i = 0; i < num_gh; i++)
         if (test_bit(HIF_WAIT, &ghs[i].gh_iflags))
             return 1;
     return 0;
 }
 
 /**
  * gfs2_glock_async_wait - wait on multiple asynchronous glock acquisitions
  * @num_gh: the number of holders in the array
  * @ghs: the glock holder array
  *
  * Returns: 0 on success, meaning all glocks have been granted and are held.
  *          -ESTALE if the request timed out, meaning all glocks were released,
  *          and the caller should retry the operation.
  */
 
 int gfs2_glock_async_wait(unsigned int num_gh, struct gfs2_holder *ghs)
 {
     struct gfs2_sbd *sdp = ghs[0].gh_gl->gl_name.ln_sbd;
     int i, ret = 0, timeout = 0;
     unsigned long start_time = jiffies;
 
     might_sleep();
     /*
      * Total up the (minimum hold time * 2) of all glocks and use that to
      * determine the max amount of time we should wait.
      */
     for (i = 0; i < num_gh; i++)
         timeout += ghs[i].gh_gl->gl_hold_time << 1;
 
     if (!wait_event_timeout(sdp->sd_async_glock_wait,
                 !glocks_pending(num_gh, ghs), timeout)) {
         ret = -ESTALE; /* request timed out. */
         goto out;
     }
 
     for (i = 0; i < num_gh; i++) {
         struct gfs2_holder *gh = &ghs[i];
         int ret2;
 
         if (test_bit(HIF_HOLDER, &gh->gh_iflags)) {
             gfs2_glock_update_hold_time(gh->gh_gl,
                             start_time);
         }
         ret2 = gfs2_glock_holder_ready(gh);
         if (!ret)
             ret = ret2;
     }
 
 out:
     if (ret) {
         for (i = 0; i < num_gh; i++) {
             struct gfs2_holder *gh = &ghs[i];
 
             gfs2_glock_dq(gh);
         }
     }
     return ret;
 }
 
 /**
  * handle_callback - process a demote request
  * @gl: the glock
  * @state: the state the caller wants us to change to
  * @delay: zero to demote immediately; otherwise pending demote
  * @remote: true if this came from a different cluster node
  *
  * There are only two requests that we are going to see in actual
  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
  */
 
 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
                 unsigned long delay, bool remote)
 {
     if (delay)
         set_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
     else
         gfs2_set_demote(gl);
     if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
         gl->gl_demote_state = state;
         gl->gl_demote_time = jiffies;
     } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
             gl->gl_demote_state != state) {
         gl->gl_demote_state = LM_ST_UNLOCKED;
     }
     if (gl->gl_ops->go_callback)
         gl->gl_ops->go_callback(gl, remote);
     trace_gfs2_demote_rq(gl, remote);
 }
 
 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
 {
     struct va_format vaf;
     va_list args;
 
     va_start(args, fmt);
 
     if (seq) {
         seq_vprintf(seq, fmt, args);
     } else {
         vaf.fmt = fmt;
         vaf.va = &args;
 
         pr_err("%pV", &vaf);
     }
 
     va_end(args);
 }
 
 /**
  * add_to_queue - Add a holder to the wait queue (but look for recursion)
  * @gh: the holder structure to add
  *
  * Eventually we should move the recursive locking trap to a
  * debugging option or something like that. This is the fast
  * path and needs to have the minimum number of distractions.
  * 
  */
 
 static inline void add_to_queue(struct gfs2_holder *gh)
 __releases(&gl->gl_lockref.lock)
 __acquires(&gl->gl_lockref.lock)
 {
     struct gfs2_glock *gl = gh->gh_gl;
     struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
     struct list_head *insert_pt = NULL;
     struct gfs2_holder *gh2;
     int try_futile = 0;
 
     GLOCK_BUG_ON(gl, gh->gh_owner_pid == NULL);
     if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
         GLOCK_BUG_ON(gl, true);
 
     if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
         if (test_bit(GLF_LOCK, &gl->gl_flags)) {
             struct gfs2_holder *current_gh;
 
             current_gh = find_first_strong_holder(gl);
             try_futile = !may_grant(gl, current_gh, gh);
         }
         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
             goto fail;
     }
 
     list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
         if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
             (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK) &&
             !test_bit(HIF_MAY_DEMOTE, &gh2->gh_iflags)))
             goto trap_recursive;
         if (try_futile &&
             !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 fail:
             gh->gh_error = GLR_TRYFAILED;
             gfs2_holder_wake(gh);
             return;
         }
         if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
             continue;
         if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
             insert_pt = &gh2->gh_list;
     }
     trace_gfs2_glock_queue(gh, 1);
     gfs2_glstats_inc(gl, GFS2_LKS_QCOUNT);
     gfs2_sbstats_inc(gl, GFS2_LKS_QCOUNT);
     if (likely(insert_pt == NULL)) {
         list_add_tail(&gh->gh_list, &gl->gl_holders);
         if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
             goto do_cancel;
         return;
     }
     list_add_tail(&gh->gh_list, insert_pt);
 do_cancel:
     gh = list_first_entry(&gl->gl_holders, struct gfs2_holder, gh_list);
     if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
         spin_unlock(&gl->gl_lockref.lock);
         if (sdp->sd_lockstruct.ls_ops->lm_cancel)
             sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
         spin_lock(&gl->gl_lockref.lock);
     }
     return;
 
 trap_recursive:
     fs_err(sdp, "original: %pSR\n", (void *)gh2->gh_ip);
     fs_err(sdp, "pid: %d\n", pid_nr(gh2->gh_owner_pid));
     fs_err(sdp, "lock type: %d req lock state : %d\n",
            gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
     fs_err(sdp, "new: %pSR\n", (void *)gh->gh_ip);
     fs_err(sdp, "pid: %d\n", pid_nr(gh->gh_owner_pid));
     fs_err(sdp, "lock type: %d req lock state : %d\n",
            gh->gh_gl->gl_name.ln_type, gh->gh_state);
     gfs2_dump_glock(NULL, gl, true);
     BUG();
 }
 
 /**
  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
  * @gh: the holder structure
  *
  * if (gh->gh_flags & GL_ASYNC), this never returns an error
  *
  * Returns: 0, GLR_TRYFAILED, or errno on failure
  */
 
 int gfs2_glock_nq(struct gfs2_holder *gh)
 {
     struct gfs2_glock *gl = gh->gh_gl;
     int error = 0;
 
     if (glock_blocked_by_withdraw(gl) && !(gh->gh_flags & LM_FLAG_NOEXP))
         return -EIO;
 
     if (test_bit(GLF_LRU, &gl->gl_flags))
         gfs2_glock_remove_from_lru(gl);
 
     gh->gh_error = 0;
     spin_lock(&gl->gl_lockref.lock);
     add_to_queue(gh);
     if (unlikely((LM_FLAG_NOEXP & gh->gh_flags) &&
              test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))) {
         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
         gl->gl_lockref.count++;
         __gfs2_glock_queue_work(gl, 0);
     }
     run_queue(gl, 1);
     spin_unlock(&gl->gl_lockref.lock);
 
     if (!(gh->gh_flags & GL_ASYNC))
         error = gfs2_glock_wait(gh);
 
     return error;
 }
 
 /**
  * gfs2_glock_poll - poll to see if an async request has been completed
  * @gh: the holder
  *
  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
  */
 
 int gfs2_glock_poll(struct gfs2_holder *gh)
 {
     return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
 }
 
 static inline bool needs_demote(struct gfs2_glock *gl)
 {
     return (test_bit(GLF_DEMOTE, &gl->gl_flags) ||
         test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags));
 }
 
 static void __gfs2_glock_dq(struct gfs2_holder *gh)
 {
     struct gfs2_glock *gl = gh->gh_gl;
     struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
     unsigned delay = 0;
     int fast_path = 0;
 
     /*
      * This while loop is similar to function demote_incompat_holders:
      * If the glock is due to be demoted (which may be from another node
      * or even if this holder is GL_NOCACHE), the weak holders are
      * demoted as well, allowing the glock to be demoted.
      */
     while (gh) {
         /*
          * If we're in the process of file system withdraw, we cannot
          * just dequeue any glocks until our journal is recovered, lest
          * we introduce file system corruption. We need two exceptions
          * to this rule: We need to allow unlocking of nondisk glocks
          * and the glock for our own journal that needs recovery.
          */
         if (test_bit(SDF_WITHDRAW_RECOVERY, &sdp->sd_flags) &&
             glock_blocked_by_withdraw(gl) &&
             gh->gh_gl != sdp->sd_jinode_gl) {
             sdp->sd_glock_dqs_held++;
             spin_unlock(&gl->gl_lockref.lock);
             might_sleep();
             wait_on_bit(&sdp->sd_flags, SDF_WITHDRAW_RECOVERY,
                     TASK_UNINTERRUPTIBLE);
             spin_lock(&gl->gl_lockref.lock);
         }
 
         /*
          * This holder should not be cached, so mark it for demote.
          * Note: this should be done before the check for needs_demote
          * below.
          */
         if (gh->gh_flags & GL_NOCACHE)
             handle_callback(gl, LM_ST_UNLOCKED, 0, false);
 
         list_del_init(&gh->gh_list);
         clear_bit(HIF_HOLDER, &gh->gh_iflags);
         trace_gfs2_glock_queue(gh, 0);
 
         /*
          * If there hasn't been a demote request we are done.
          * (Let the remaining holders, if any, keep holding it.)
          */
         if (!needs_demote(gl)) {
             if (list_empty(&gl->gl_holders))
                 fast_path = 1;
             break;
         }
         /*
          * If we have another strong holder (we cannot auto-demote)
          * we are done. It keeps holding it until it is done.
          */
         if (find_first_strong_holder(gl))
             break;
 
         /*
          * If we have a weak holder at the head of the list, it
          * (and all others like it) must be auto-demoted. If there
          * are no more weak holders, we exit the while loop.
          */
         gh = find_first_holder(gl);
     }
 
     if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl))
         gfs2_glock_add_to_lru(gl);
 
     if (unlikely(!fast_path)) {
         gl->gl_lockref.count++;
         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
             !test_bit(GLF_DEMOTE, &gl->gl_flags) &&
             gl->gl_name.ln_type == LM_TYPE_INODE)
             delay = gl->gl_hold_time;
         __gfs2_glock_queue_work(gl, delay);
     }
 }
 
 /**
  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
  * @gh: the glock holder
  *
  */
 void gfs2_glock_dq(struct gfs2_holder *gh)
 {
     struct gfs2_glock *gl = gh->gh_gl;
 
     spin_lock(&gl->gl_lockref.lock);
     if (list_is_first(&gh->gh_list, &gl->gl_holders) &&
         !test_bit(HIF_HOLDER, &gh->gh_iflags)) {
         spin_unlock(&gl->gl_lockref.lock);
         gl->gl_name.ln_sbd->sd_lockstruct.ls_ops->lm_cancel(gl);
         wait_on_bit(&gh->gh_iflags, HIF_WAIT, TASK_UNINTERRUPTIBLE);
         spin_lock(&gl->gl_lockref.lock);
     }
 
     __gfs2_glock_dq(gh);
     spin_unlock(&gl->gl_lockref.lock);
 }
 
 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
 {
     struct gfs2_glock *gl = gh->gh_gl;
     gfs2_glock_dq(gh);
     might_sleep();
     wait_on_bit(&gl->gl_flags, GLF_DEMOTE, TASK_UNINTERRUPTIBLE);
 }
 
 /**
  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
  * @gh: the holder structure
  *
  */
 
 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
 {
     gfs2_glock_dq(gh);
     gfs2_holder_uninit(gh);
 }
 
 /**
  * gfs2_glock_nq_num - acquire a glock based on lock number
  * @sdp: the filesystem
  * @number: the lock number
  * @glops: the glock operations for the type of glock
  * @state: the state to acquire the glock in
  * @flags: modifier flags for the acquisition
  * @gh: the struct gfs2_holder
  *
  * Returns: errno
  */
 
 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
               const struct gfs2_glock_operations *glops,
               unsigned int state, u16 flags, struct gfs2_holder *gh)
 {
     struct gfs2_glock *gl;
     int error;
 
     error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
     if (!error) {
         error = gfs2_glock_nq_init(gl, state, flags, gh);
         gfs2_glock_put(gl);
     }
 
     return error;
 }
 
 /**
  * glock_compare - Compare two struct gfs2_glock structures for sorting
  * @arg_a: the first structure
  * @arg_b: the second structure
  *
  */
 
 static int glock_compare(const void *arg_a, const void *arg_b)
 {
     const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
     const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
     const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
     const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
 
     if (a->ln_number > b->ln_number)
         return 1;
     if (a->ln_number < b->ln_number)
         return -1;
     BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
     return 0;
 }
 
 /**
  * nq_m_sync - synchronously acquire more than one glock in deadlock free order
  * @num_gh: the number of structures
  * @ghs: an array of struct gfs2_holder structures
  * @p: placeholder for the holder structure to pass back
  *
  * Returns: 0 on success (all glocks acquired),
  *          errno on failure (no glocks acquired)
  */
 
 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
              struct gfs2_holder **p)
 {
     unsigned int x;
     int error = 0;
 
     for (x = 0; x < num_gh; x++)
         p[x] = &ghs[x];
 
     sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
 
     for (x = 0; x < num_gh; x++) {
         error = gfs2_glock_nq(p[x]);
         if (error) {
             while (x--)
                 gfs2_glock_dq(p[x]);
             break;
         }
     }
 
     return error;
 }
 
 /**
  * gfs2_glock_nq_m - acquire multiple glocks
  * @num_gh: the number of structures
  * @ghs: an array of struct gfs2_holder structures
  *
  * Returns: 0 on success (all glocks acquired),
  *          errno on failure (no glocks acquired)
  */
 
 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
 {
     struct gfs2_holder *tmp[4];
     struct gfs2_holder **pph = tmp;
     int error = 0;
 
     switch(num_gh) {
     case 0:
         return 0;
     case 1:
         return gfs2_glock_nq(ghs);
     default:
         if (num_gh <= 4)
             break;
         pph = kmalloc_array(num_gh, sizeof(struct gfs2_holder *),
                     GFP_NOFS);
         if (!pph)
             return -ENOMEM;
     }
 
     error = nq_m_sync(num_gh, ghs, pph);
 
     if (pph != tmp)
         kfree(pph);
 
     return error;
 }
 
 /**
  * gfs2_glock_dq_m - release multiple glocks
  * @num_gh: the number of structures
  * @ghs: an array of struct gfs2_holder structures
  *
  */
 
 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
 {
     while (num_gh--)
         gfs2_glock_dq(&ghs[num_gh]);
 }
 
 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
 {
     unsigned long delay = 0;
     unsigned long holdtime;
     unsigned long now = jiffies;
 
     gfs2_glock_hold(gl);
     spin_lock(&gl->gl_lockref.lock);
     holdtime = gl->gl_tchange + gl->gl_hold_time;
     if (!list_empty(&gl->gl_holders) &&
         gl->gl_name.ln_type == LM_TYPE_INODE) {
         if (time_before(now, holdtime))
             delay = holdtime - now;
         if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
             delay = gl->gl_hold_time;
     }
     /*
      * Note 1: We cannot call demote_incompat_holders from handle_callback
      * or gfs2_set_demote due to recursion problems like: gfs2_glock_dq ->
      * handle_callback -> demote_incompat_holders -> gfs2_glock_dq
      * Plus, we only want to demote the holders if the request comes from
      * a remote cluster node because local holder conflicts are resolved
      * elsewhere.
      *
      * Note 2: if a remote node wants this glock in EX mode, lock_dlm will
      * request that we set our state to UNLOCKED. Here we mock up a holder
      * to make it look like someone wants the lock EX locally. Any SH
      * and DF requests should be able to share the lock without demoting.
      *
      * Note 3: We only want to demote the demoteable holders when there
      * are no more strong holders. The demoteable holders might as well
      * keep the glock until the last strong holder is done with it.
      */
     if (!find_first_strong_holder(gl)) {
         struct gfs2_holder mock_gh = {
             .gh_gl = gl,
             .gh_state = (state == LM_ST_UNLOCKED) ?
                     LM_ST_EXCLUSIVE : state,
             .gh_iflags = BIT(HIF_HOLDER)
         };
 
         demote_incompat_holders(gl, &mock_gh);
     }
     handle_callback(gl, state, delay, true);
     __gfs2_glock_queue_work(gl, delay);
     spin_unlock(&gl->gl_lockref.lock);
 }
 
 /**
  * gfs2_should_freeze - Figure out if glock should be frozen
  * @gl: The glock in question
  *
  * Glocks are not frozen if (a) the result of the dlm operation is
  * an error, (b) the locking operation was an unlock operation or
  * (c) if there is a "noexp" flagged request anywhere in the queue
  *
  * Returns: 1 if freezing should occur, 0 otherwise
  */
 
 static int gfs2_should_freeze(const struct gfs2_glock *gl)
 {
     const struct gfs2_holder *gh;
 
     if (gl->gl_reply & ~LM_OUT_ST_MASK)
         return 0;
     if (gl->gl_target == LM_ST_UNLOCKED)
         return 0;
 
     list_for_each_entry(gh, &gl->gl_holders, gh_list) {
         if (test_bit(HIF_HOLDER, &gh->gh_iflags))
             continue;
         if (LM_FLAG_NOEXP & gh->gh_flags)
             return 0;
     }
 
     return 1;
 }
 
 /**
  * gfs2_glock_complete - Callback used by locking
  * @gl: Pointer to the glock
  * @ret: The return value from the dlm
  *
  * The gl_reply field is under the gl_lockref.lock lock so that it is ok
  * to use a bitfield shared with other glock state fields.
  */
 
 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
 {
     struct lm_lockstruct *ls = &gl->gl_name.ln_sbd->sd_lockstruct;
 
     spin_lock(&gl->gl_lockref.lock);
     gl->gl_reply = ret;
 
     if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags))) {
         if (gfs2_should_freeze(gl)) {
             set_bit(GLF_FROZEN, &gl->gl_flags);
             spin_unlock(&gl->gl_lockref.lock);
             return;
         }
     }
 
     gl->gl_lockref.count++;
     set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
     __gfs2_glock_queue_work(gl, 0);
     spin_unlock(&gl->gl_lockref.lock);
 }
 
 static int glock_cmp(void *priv, const struct list_head *a,
              const struct list_head *b)
 {
     struct gfs2_glock *gla, *glb;
 
     gla = list_entry(a, struct gfs2_glock, gl_lru);
     glb = list_entry(b, struct gfs2_glock, gl_lru);
 
     if (gla->gl_name.ln_number > glb->gl_name.ln_number)
         return 1;
     if (gla->gl_name.ln_number < glb->gl_name.ln_number)
         return -1;
 
     return 0;
 }
 
 /**
  * gfs2_dispose_glock_lru - Demote a list of glocks
  * @list: The list to dispose of
  *
  * Disposing of glocks may involve disk accesses, so that here we sort
  * the glocks by number (i.e. disk location of the inodes) so that if
  * there are any such accesses, they'll be sent in order (mostly).
  *
  * Must be called under the lru_lock, but may drop and retake this
  * lock. While the lru_lock is dropped, entries may vanish from the
  * list, but no new entries will appear on the list (since it is
  * private)
  */
 
 static void gfs2_dispose_glock_lru(struct list_head *list)
 __releases(&lru_lock)
 __acquires(&lru_lock)
 {
     struct gfs2_glock *gl;
 
     list_sort(NULL, list, glock_cmp);
 
     while(!list_empty(list)) {
         gl = list_first_entry(list, struct gfs2_glock, gl_lru);
         list_del_init(&gl->gl_lru);
         clear_bit(GLF_LRU, &gl->gl_flags);
         if (!spin_trylock(&gl->gl_lockref.lock)) {
 add_back_to_lru:
             list_add(&gl->gl_lru, &lru_list);
             set_bit(GLF_LRU, &gl->gl_flags);
             atomic_inc(&lru_count);
             continue;
         }
         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
             spin_unlock(&gl->gl_lockref.lock);
             goto add_back_to_lru;
         }
         gl->gl_lockref.count++;
         if (demote_ok(gl))
             handle_callback(gl, LM_ST_UNLOCKED, 0, false);
         WARN_ON(!test_and_clear_bit(GLF_LOCK, &gl->gl_flags));
         __gfs2_glock_queue_work(gl, 0);
         spin_unlock(&gl->gl_lockref.lock);
         cond_resched_lock(&lru_lock);
     }
 }
 
 /**
  * gfs2_scan_glock_lru - Scan the LRU looking for locks to demote
  * @nr: The number of entries to scan
  *
  * This function selects the entries on the LRU which are able to
  * be demoted, and then kicks off the process by calling
  * gfs2_dispose_glock_lru() above.
  */
 
 static long gfs2_scan_glock_lru(int nr)
 {
     struct gfs2_glock *gl;
     LIST_HEAD(skipped);
     LIST_HEAD(dispose);
     long freed = 0;
 
     spin_lock(&lru_lock);
     while ((nr-- >= 0) && !list_empty(&lru_list)) {
         gl = list_first_entry(&lru_list, struct gfs2_glock, gl_lru);
 
         /* Test for being demotable */
         if (!test_bit(GLF_LOCK, &gl->gl_flags)) {
             list_move(&gl->gl_lru, &dispose);
             atomic_dec(&lru_count);
             freed++;
             continue;
         }
 
         list_move(&gl->gl_lru, &skipped);
     }
     list_splice(&skipped, &lru_list);
     if (!list_empty(&dispose))
         gfs2_dispose_glock_lru(&dispose);
     spin_unlock(&lru_lock);
 
     return freed;
 }
 
 static unsigned long gfs2_glock_shrink_scan(struct shrinker *shrink,
                         struct shrink_control *sc)
 {
     if (!(sc->gfp_mask & __GFP_FS))
         return SHRINK_STOP;
     return gfs2_scan_glock_lru(sc->nr_to_scan);
 }
 
 static unsigned long gfs2_glock_shrink_count(struct shrinker *shrink,
                          struct shrink_control *sc)
 {
     return vfs_pressure_ratio(atomic_read(&lru_count));
 }
 
 static struct shrinker glock_shrinker = {
     .seeks = DEFAULT_SEEKS,
     .count_objects = gfs2_glock_shrink_count,
     .scan_objects = gfs2_glock_shrink_scan,
 };
 
 /**
  * glock_hash_walk - Call a function for glock in a hash bucket
  * @examiner: the function
  * @sdp: the filesystem
  *
  * Note that the function can be called multiple times on the same
  * object.  So the user must ensure that the function can cope with
  * that.
  */
 
 static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
 {
     struct gfs2_glock *gl;
     struct rhashtable_iter iter;
 
     rhashtable_walk_enter(&gl_hash_table, &iter);
 
     do {
         rhashtable_walk_start(&iter);
 
         while ((gl = rhashtable_walk_next(&iter)) && !IS_ERR(gl)) {
             if (gl->gl_name.ln_sbd == sdp)
                 examiner(gl);
         }
 
         rhashtable_walk_stop(&iter);
     } while (cond_resched(), gl == ERR_PTR(-EAGAIN));
 
     rhashtable_walk_exit(&iter);
 }
 
 bool gfs2_queue_delete_work(struct gfs2_glock *gl, unsigned long delay)
 {
     bool queued;
 
     spin_lock(&gl->gl_lockref.lock);
     queued = queue_delayed_work(gfs2_delete_workqueue,
                     &gl->gl_delete, delay);
     if (queued)
         set_bit(GLF_PENDING_DELETE, &gl->gl_flags);
     spin_unlock(&gl->gl_lockref.lock);
     return queued;
 }
 
 void gfs2_cancel_delete_work(struct gfs2_glock *gl)
 {
     if (cancel_delayed_work(&gl->gl_delete)) {
         clear_bit(GLF_PENDING_DELETE, &gl->gl_flags);
         gfs2_glock_put(gl);
     }
 }
 
 bool gfs2_delete_work_queued(const struct gfs2_glock *gl)
 {
     return test_bit(GLF_PENDING_DELETE, &gl->gl_flags);
 }
 
 static void flush_delete_work(struct gfs2_glock *gl)
 {
     if (gl->gl_name.ln_type == LM_TYPE_IOPEN) {
         if (cancel_delayed_work(&gl->gl_delete)) {
             queue_delayed_work(gfs2_delete_workqueue,
                        &gl->gl_delete, 0);
         }
     }
 }
 
 void gfs2_flush_delete_work(struct gfs2_sbd *sdp)
 {
     glock_hash_walk(flush_delete_work, sdp);
     flush_workqueue(gfs2_delete_workqueue);
 }
 
 /**
  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
  * @gl: The glock to thaw
  *
  */
 
 static void thaw_glock(struct gfs2_glock *gl)
 {
     if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
         return;
     if (!lockref_get_not_dead(&gl->gl_lockref))
         return;
     set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
     gfs2_glock_queue_work(gl, 0);
 }
 
 /**
  * clear_glock - look at a glock and see if we can free it from glock cache
  * @gl: the glock to look at
  *
  */
 
 static void clear_glock(struct gfs2_glock *gl)
 {
     gfs2_glock_remove_from_lru(gl);
 
     spin_lock(&gl->gl_lockref.lock);
     if (!__lockref_is_dead(&gl->gl_lockref)) {
         gl->gl_lockref.count++;
         if (gl->gl_state != LM_ST_UNLOCKED)
             handle_callback(gl, LM_ST_UNLOCKED, 0, false);
         __gfs2_glock_queue_work(gl, 0);
     }
     spin_unlock(&gl->gl_lockref.lock);
 }
 
 /**
  * gfs2_glock_thaw - Thaw any frozen glocks
  * @sdp: The super block
  *
  */
 
 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
 {
     glock_hash_walk(thaw_glock, sdp);
 }
 
 static void dump_glock(struct seq_file *seq, struct gfs2_glock *gl, bool fsid)
 {
     spin_lock(&gl->gl_lockref.lock);
     gfs2_dump_glock(seq, gl, fsid);
     spin_unlock(&gl->gl_lockref.lock);
 }
 
 static void dump_glock_func(struct gfs2_glock *gl)
 {
     dump_glock(NULL, gl, true);
 }
 
 /**
  * gfs2_gl_hash_clear - Empty out the glock hash table
  * @sdp: the filesystem
  *
  * Called when unmounting the filesystem.
  */
 
 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
 {
     set_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags);
     flush_workqueue(glock_workqueue);
     glock_hash_walk(clear_glock, sdp);
     flush_workqueue(glock_workqueue);
     wait_event_timeout(sdp->sd_glock_wait,
                atomic_read(&sdp->sd_glock_disposal) == 0,
                HZ * 600);
     glock_hash_walk(dump_glock_func, sdp);
 }
 
 static const char *state2str(unsigned state)
 {
     switch(state) {
     case LM_ST_UNLOCKED:
         return "UN";
     case LM_ST_SHARED:
         return "SH";
     case LM_ST_DEFERRED:
         return "DF";
     case LM_ST_EXCLUSIVE:
         return "EX";
     }
     return "??";
 }
 
 static const char *hflags2str(char *buf, u16 flags, unsigned long iflags)
 {
     char *p = buf;
     if (flags & LM_FLAG_TRY)
         *p++ = 't';
     if (flags & LM_FLAG_TRY_1CB)
         *p++ = 'T';
     if (flags & LM_FLAG_NOEXP)
         *p++ = 'e';
     if (flags & LM_FLAG_ANY)
         *p++ = 'A';
     if (flags & LM_FLAG_PRIORITY)
         *p++ = 'p';
     if (flags & LM_FLAG_NODE_SCOPE)
         *p++ = 'n';
     if (flags & GL_ASYNC)
         *p++ = 'a';
     if (flags & GL_EXACT)
         *p++ = 'E';
     if (flags & GL_NOCACHE)
         *p++ = 'c';
     if (test_bit(HIF_HOLDER, &iflags))
         *p++ = 'H';
     if (test_bit(HIF_WAIT, &iflags))
         *p++ = 'W';
     if (test_bit(HIF_MAY_DEMOTE, &iflags))
         *p++ = 'D';
     if (flags & GL_SKIP)
         *p++ = 's';
     *p = 0;
     return buf;
 }
 
 /**
  * dump_holder - print information about a glock holder
  * @seq: the seq_file struct
  * @gh: the glock holder
  * @fs_id_buf: pointer to file system id (if requested)
  *
  */
 
 static void dump_holder(struct seq_file *seq, const struct gfs2_holder *gh,
             const char *fs_id_buf)
 {
     struct task_struct *gh_owner = NULL;
     char flags_buf[32];
 
     rcu_read_lock();
     if (gh->gh_owner_pid)
         gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
     gfs2_print_dbg(seq, "%s H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
                fs_id_buf, state2str(gh->gh_state),
                hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
                gh->gh_error,
                gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
                gh_owner ? gh_owner->comm : "(ended)",
                (void *)gh->gh_ip);
     rcu_read_unlock();
 }
 
 static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
 {
     const unsigned long *gflags = &gl->gl_flags;
     char *p = buf;
 
     if (test_bit(GLF_LOCK, gflags))
         *p++ = 'l';
     if (test_bit(GLF_DEMOTE, gflags))
         *p++ = 'D';
     if (test_bit(GLF_PENDING_DEMOTE, gflags))
         *p++ = 'd';
     if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
         *p++ = 'p';
     if (test_bit(GLF_DIRTY, gflags))
         *p++ = 'y';
     if (test_bit(GLF_LFLUSH, gflags))
         *p++ = 'f';
     if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
         *p++ = 'i';
     if (test_bit(GLF_REPLY_PENDING, gflags))
         *p++ = 'r';
     if (test_bit(GLF_INITIAL, gflags))
         *p++ = 'I';
     if (test_bit(GLF_FROZEN, gflags))
         *p++ = 'F';
     if (!list_empty(&gl->gl_holders))
         *p++ = 'q';
     if (test_bit(GLF_LRU, gflags))
         *p++ = 'L';
     if (gl->gl_object)
         *p++ = 'o';
     if (test_bit(GLF_BLOCKING, gflags))
         *p++ = 'b';
     if (test_bit(GLF_PENDING_DELETE, gflags))
         *p++ = 'P';
     if (test_bit(GLF_FREEING, gflags))
         *p++ = 'x';
     if (test_bit(GLF_INSTANTIATE_NEEDED, gflags))
         *p++ = 'n';
     if (test_bit(GLF_INSTANTIATE_IN_PROG, gflags))
         *p++ = 'N';
     *p = 0;
     return buf;
 }
 
 /**
  * gfs2_dump_glock - print information about a glock
  * @seq: The seq_file struct
  * @gl: the glock
  * @fsid: If true, also dump the file system id
  *
  * The file format is as follows:
  * One line per object, capital letters are used to indicate objects
  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
  * other objects are indented by a single space and follow the glock to
  * which they are related. Fields are indicated by lower case letters
  * followed by a colon and the field value, except for strings which are in
  * [] so that its possible to see if they are composed of spaces for
  * example. The field's are n = number (id of the object), f = flags,
  * t = type, s = state, r = refcount, e = error, p = pid.
  *
  */
 
 void gfs2_dump_glock(struct seq_file *seq, struct gfs2_glock *gl, bool fsid)
 {
     const struct gfs2_glock_operations *glops = gl->gl_ops;
     unsigned long long dtime;
     const struct gfs2_holder *gh;
     char gflags_buf[32];
     struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
     char fs_id_buf[sizeof(sdp->sd_fsname) + 7];
     unsigned long nrpages = 0;
 
     if (gl->gl_ops->go_flags & GLOF_ASPACE) {
         struct address_space *mapping = gfs2_glock2aspace(gl);
 
         nrpages = mapping->nrpages;
     }
     memset(fs_id_buf, 0, sizeof(fs_id_buf));
     if (fsid && sdp) /* safety precaution */
         sprintf(fs_id_buf, "fsid=%s: ", sdp->sd_fsname);
     dtime = jiffies - gl->gl_demote_time;
     dtime *= 1000000/HZ; /* demote time in uSec */
     if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
         dtime = 0;
     gfs2_print_dbg(seq, "%sG:  s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d "
                "v:%d r:%d m:%ld p:%lu\n",
                fs_id_buf, state2str(gl->gl_state),
                gl->gl_name.ln_type,
                (unsigned long long)gl->gl_name.ln_number,
                gflags2str(gflags_buf, gl),
                state2str(gl->gl_target),
                state2str(gl->gl_demote_state), dtime,
                atomic_read(&gl->gl_ail_count),
                atomic_read(&gl->gl_revokes),
                (int)gl->gl_lockref.count, gl->gl_hold_time, nrpages);
 
     list_for_each_entry(gh, &gl->gl_holders, gh_list)
         dump_holder(seq, gh, fs_id_buf);
 
     if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
         glops->go_dump(seq, gl, fs_id_buf);
 }
 
 static int gfs2_glstats_seq_show(struct seq_file *seq, void *iter_ptr)
 {
     struct gfs2_glock *gl = iter_ptr;
 
     seq_printf(seq, "G: n:%u/%llx rtt:%llu/%llu rttb:%llu/%llu irt:%llu/%llu dcnt: %llu qcnt: %llu\n",
            gl->gl_name.ln_type,
            (unsigned long long)gl->gl_name.ln_number,
            (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTT],
            (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTVAR],
            (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTB],
            (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTVARB],
            (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SIRT],
            (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SIRTVAR],
            (unsigned long long)gl->gl_stats.stats[GFS2_LKS_DCOUNT],
            (unsigned long long)gl->gl_stats.stats[GFS2_LKS_QCOUNT]);
     return 0;
 }
 
 static const char *gfs2_gltype[] = {
     "type",
     "reserved",
     "nondisk",
     "inode",
     "rgrp",
     "meta",
     "iopen",
     "flock",
     "plock",
     "quota",
     "journal",
 };
 
 static const char *gfs2_stype[] = {
     [GFS2_LKS_SRTT]     = "srtt",
     [GFS2_LKS_SRTTVAR]  = "srttvar",
     [GFS2_LKS_SRTTB]    = "srttb",
     [GFS2_LKS_SRTTVARB] = "srttvarb",
     [GFS2_LKS_SIRT]     = "sirt",
     [GFS2_LKS_SIRTVAR]  = "sirtvar",
     [GFS2_LKS_DCOUNT]   = "dlm",
     [GFS2_LKS_QCOUNT]   = "queue",
 };
 
 #define GFS2_NR_SBSTATS (ARRAY_SIZE(gfs2_gltype) * ARRAY_SIZE(gfs2_stype))
 
 static int gfs2_sbstats_seq_show(struct seq_file *seq, void *iter_ptr)
 {
     struct gfs2_sbd *sdp = seq->private;
     loff_t pos = *(loff_t *)iter_ptr;
     unsigned index = pos >> 3;
     unsigned subindex = pos & 0x07;
     int i;
 
     if (index == 0 && subindex != 0)
         return 0;
 
     seq_printf(seq, "%-10s %8s:", gfs2_gltype[index],
            (index == 0) ? "cpu": gfs2_stype[subindex]);
 
     for_each_possible_cpu(i) {
                 const struct gfs2_pcpu_lkstats *lkstats = per_cpu_ptr(sdp->sd_lkstats, i);
 
         if (index == 0)
             seq_printf(seq, " %15u", i);
         else
             seq_printf(seq, " %15llu", (unsigned long long)lkstats->
                    lkstats[index - 1].stats[subindex]);
     }
     seq_putc(seq, '\n');
     return 0;
 }
 
 int __init gfs2_glock_init(void)
 {
     int i, ret;
 
     ret = rhashtable_init(&gl_hash_table, &ht_parms);
     if (ret < 0)
         return ret;
 
     glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
                       WQ_HIGHPRI | WQ_FREEZABLE, 0);
     if (!glock_workqueue) {
         rhashtable_destroy(&gl_hash_table);
         return -ENOMEM;
     }
     gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
                         WQ_MEM_RECLAIM | WQ_FREEZABLE,
                         0);
     if (!gfs2_delete_workqueue) {
         destroy_workqueue(glock_workqueue);
         rhashtable_destroy(&gl_hash_table);
         return -ENOMEM;
     }
 
     ret = register_shrinker(&glock_shrinker, "gfs2-glock");
     if (ret) {
         destroy_workqueue(gfs2_delete_workqueue);
         destroy_workqueue(glock_workqueue);
         rhashtable_destroy(&gl_hash_table);
         return ret;
     }
 
     for (i = 0; i < GLOCK_WAIT_TABLE_SIZE; i++)
         init_waitqueue_head(glock_wait_table + i);
 
     return 0;
 }
 
 void gfs2_glock_exit(void)
 {
     unregister_shrinker(&glock_shrinker);
     rhashtable_destroy(&gl_hash_table);
     destroy_workqueue(glock_workqueue);
     destroy_workqueue(gfs2_delete_workqueue);
 }
 
 static void gfs2_glock_iter_next(struct gfs2_glock_iter *gi, loff_t n)
 {
     struct gfs2_glock *gl = gi->gl;
 
     if (gl) {
         if (n == 0)
             return;
         if (!lockref_put_not_zero(&gl->gl_lockref))
             gfs2_glock_queue_put(gl);
     }
     for (;;) {
         gl = rhashtable_walk_next(&gi->hti);
         if (IS_ERR_OR_NULL(gl)) {
             if (gl == ERR_PTR(-EAGAIN)) {
                 n = 1;
                 continue;
             }
             gl = NULL;
             break;
         }
         if (gl->gl_name.ln_sbd != gi->sdp)
             continue;
         if (n <= 1) {
             if (!lockref_get_not_dead(&gl->gl_lockref))
                 continue;
             break;
         } else {
             if (__lockref_is_dead(&gl->gl_lockref))
                 continue;
             n--;
         }
     }
     gi->gl = gl;
 }
 
 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
     __acquires(RCU)
 {
     struct gfs2_glock_iter *gi = seq->private;
     loff_t n;
 
     /*
      * We can either stay where we are, skip to the next hash table
      * entry, or start from the beginning.
      */
     if (*pos < gi->last_pos) {
         rhashtable_walk_exit(&gi->hti);
         rhashtable_walk_enter(&gl_hash_table, &gi->hti);
         n = *pos + 1;
     } else {
         n = *pos - gi->last_pos;
     }
 
     rhashtable_walk_start(&gi->hti);
 
     gfs2_glock_iter_next(gi, n);
     gi->last_pos = *pos;
     return gi->gl;
 }
 
 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
                  loff_t *pos)
 {
     struct gfs2_glock_iter *gi = seq->private;
 
     (*pos)++;
     gi->last_pos = *pos;
     gfs2_glock_iter_next(gi, 1);
     return gi->gl;
 }
 
 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
     __releases(RCU)
 {
     struct gfs2_glock_iter *gi = seq->private;
 
     rhashtable_walk_stop(&gi->hti);
 }
 
 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
 {
     dump_glock(seq, iter_ptr, false);
     return 0;
 }
 
 static void *gfs2_sbstats_seq_start(struct seq_file *seq, loff_t *pos)
 {
     preempt_disable();
     if (*pos >= GFS2_NR_SBSTATS)
         return NULL;
     return pos;
 }
 
 static void *gfs2_sbstats_seq_next(struct seq_file *seq, void *iter_ptr,
                    loff_t *pos)
 {
     (*pos)++;
     if (*pos >= GFS2_NR_SBSTATS)
         return NULL;
     return pos;
 }
 
 static void gfs2_sbstats_seq_stop(struct seq_file *seq, void *iter_ptr)
 {
     preempt_enable();
 }
 
 static const struct seq_operations gfs2_glock_seq_ops = {
     .start = gfs2_glock_seq_start,
     .next  = gfs2_glock_seq_next,
     .stop  = gfs2_glock_seq_stop,
     .show  = gfs2_glock_seq_show,
 };
 
 static const struct seq_operations gfs2_glstats_seq_ops = {
     .start = gfs2_glock_seq_start,
     .next  = gfs2_glock_seq_next,
     .stop  = gfs2_glock_seq_stop,
     .show  = gfs2_glstats_seq_show,
 };
 
 static const struct seq_operations gfs2_sbstats_sops = {
     .start = gfs2_sbstats_seq_start,
     .next  = gfs2_sbstats_seq_next,
     .stop  = gfs2_sbstats_seq_stop,
     .show  = gfs2_sbstats_seq_show,
 };
 
 #define GFS2_SEQ_GOODSIZE min(PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER, 65536UL)
 
 static int __gfs2_glocks_open(struct inode *inode, struct file *file,
                   const struct seq_operations *ops)
 {
     int ret = seq_open_private(file, ops, sizeof(struct gfs2_glock_iter));
     if (ret == 0) {
         struct seq_file *seq = file->private_data;
         struct gfs2_glock_iter *gi = seq->private;
 
         gi->sdp = inode->i_private;
         seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
         if (seq->buf)
             seq->size = GFS2_SEQ_GOODSIZE;
         /*
          * Initially, we are "before" the first hash table entry; the
          * first call to rhashtable_walk_next gets us the first entry.
          */
         gi->last_pos = -1;
         gi->gl = NULL;
         rhashtable_walk_enter(&gl_hash_table, &gi->hti);
     }
     return ret;
 }
 
 static int gfs2_glocks_open(struct inode *inode, struct file *file)
 {
     return __gfs2_glocks_open(inode, file, &gfs2_glock_seq_ops);
 }
 
 static int gfs2_glocks_release(struct inode *inode, struct file *file)
 {
     struct seq_file *seq = file->private_data;
     struct gfs2_glock_iter *gi = seq->private;
 
     if (gi->gl)
         gfs2_glock_put(gi->gl);
     rhashtable_walk_exit(&gi->hti);
     return seq_release_private(inode, file);
 }
 
 static int gfs2_glstats_open(struct inode *inode, struct file *file)
 {
     return __gfs2_glocks_open(inode, file, &gfs2_glstats_seq_ops);
 }
 
 static const struct file_operations gfs2_glocks_fops = {
     .owner   = THIS_MODULE,
     .open    = gfs2_glocks_open,
     .read    = seq_read,
     .llseek  = seq_lseek,
     .release = gfs2_glocks_release,
 };
 
 static const struct file_operations gfs2_glstats_fops = {
     .owner   = THIS_MODULE,
     .open    = gfs2_glstats_open,
     .read    = seq_read,
     .llseek  = seq_lseek,
     .release = gfs2_glocks_release,
 };
 
 DEFINE_SEQ_ATTRIBUTE(gfs2_sbstats);
 
 void gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
 {
     sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
 
     debugfs_create_file("glocks", S_IFREG | S_IRUGO, sdp->debugfs_dir, sdp,
                 &gfs2_glocks_fops);
 
     debugfs_create_file("glstats", S_IFREG | S_IRUGO, sdp->debugfs_dir, sdp,
                 &gfs2_glstats_fops);
 
     debugfs_create_file("sbstats", S_IFREG | S_IRUGO, sdp->debugfs_dir, sdp,
                 &gfs2_sbstats_fops);
 }
 
 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
 {
     debugfs_remove_recursive(sdp->debugfs_dir);
     sdp->debugfs_dir = NULL;
 }
 
 void gfs2_register_debugfs(void)
 {
     gfs2_root = debugfs_create_dir("gfs2", NULL);
 }
 
 void gfs2_unregister_debugfs(void)
 {
     debugfs_remove(gfs2_root);
     gfs2_root = NULL;
 }