Initial import

1 files changed, 2119 insertions, 0 deletions

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
new file mode 100644
index 000000000..0fa8062f8
--- /dev/null
+++ b/fs/gfs2/glock.c
@@ -0,0 +1,2119 @@
+/*
+ * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
+ * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU General Public License version 2.
+ */
+
+#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/jhash.h>
+#include <linux/kallsyms.h>
+#include <linux/gfs2_ondisk.h>
+#include <linux/list.h>
+#include <linux/wait.h>
+#include <linux/module.h>
+#include <asm/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 "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 {
+	int hash;			/* hash bucket index           */
+	unsigned nhash;			/* Index within current bucket */
+	struct gfs2_sbd *sdp;		/* incore superblock           */
+	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 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       (1 << GFS2_GL_HASH_SHIFT)
+#define GFS2_GL_HASH_MASK       (GFS2_GL_HASH_SIZE - 1)
+
+static struct hlist_bl_head gl_hash_table[GFS2_GL_HASH_SIZE];
+static struct dentry *gfs2_root;
+
+/**
+ * gl_hash() - Turn glock number into hash bucket number
+ * @lock: The glock number
+ *
+ * Returns: The number of the corresponding hash bucket
+ */
+
+static unsigned int gl_hash(const struct gfs2_sbd *sdp,
+			    const struct lm_lockname *name)
+{
+	unsigned int h;
+
+	h = jhash(&name->ln_number, sizeof(u64), 0);
+	h = jhash(&name->ln_type, sizeof(unsigned int), h);
+	h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
+	h &= GFS2_GL_HASH_MASK;
+
+	return h;
+}
+
+static inline void spin_lock_bucket(unsigned int hash)
+{
+	hlist_bl_lock(&gl_hash_table[hash]);
+}
+
+static inline void spin_unlock_bucket(unsigned int hash)
+{
+	hlist_bl_unlock(&gl_hash_table[hash]);
+}
+
+static void gfs2_glock_dealloc(struct rcu_head *rcu)
+{
+	struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
+
+	if (gl->gl_ops->go_flags & GLOF_ASPACE) {
+		kmem_cache_free(gfs2_glock_aspace_cachep, gl);
+	} else {
+		kfree(gl->gl_lksb.sb_lvbptr);
+		kmem_cache_free(gfs2_glock_cachep, gl);
+	}
+}
+
+void gfs2_glock_free(struct gfs2_glock *gl)
+{
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+
+	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
+ *
+ */
+
+static 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;
+	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)
+{
+	spin_lock(&lru_lock);
+
+	if (!list_empty(&gl->gl_lru))
+		list_del_init(&gl->gl_lru);
+	else
+		atomic_inc(&lru_count);
+
+	list_add_tail(&gl->gl_lru, &lru_list);
+	set_bit(GLF_LRU, &gl->gl_flags);
+	spin_unlock(&lru_lock);
+}
+
+static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
+{
+	spin_lock(&lru_lock);
+	if (!list_empty(&gl->gl_lru)) {
+		list_del_init(&gl->gl_lru);
+		atomic_dec(&lru_count);
+		clear_bit(GLF_LRU, &gl->gl_flags);
+	}
+	spin_unlock(&lru_lock);
+}
+
+/**
+ * gfs2_glock_put() - Decrement reference count on glock
+ * @gl: The glock to put
+ *
+ */
+
+void gfs2_glock_put(struct gfs2_glock *gl)
+{
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct address_space *mapping = gfs2_glock2aspace(gl);
+
+	if (lockref_put_or_lock(&gl->gl_lockref))
+		return;
+
+	lockref_mark_dead(&gl->gl_lockref);
+
+	gfs2_glock_remove_from_lru(gl);
+	spin_unlock(&gl->gl_lockref.lock);
+	spin_lock_bucket(gl->gl_hash);
+	hlist_bl_del_rcu(&gl->gl_list);
+	spin_unlock_bucket(gl->gl_hash);
+	GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
+	GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
+	trace_gfs2_glock_put(gl);
+	sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
+}
+
+/**
+ * search_bucket() - Find struct gfs2_glock by lock number
+ * @bucket: the bucket to search
+ * @name: The lock name
+ *
+ * Returns: NULL, or the struct gfs2_glock with the requested number
+ */
+
+static struct gfs2_glock *search_bucket(unsigned int hash,
+					const struct gfs2_sbd *sdp,
+					const struct lm_lockname *name)
+{
+	struct gfs2_glock *gl;
+	struct hlist_bl_node *h;
+
+	hlist_bl_for_each_entry_rcu(gl, h, &gl_hash_table[hash], gl_list) {
+		if (!lm_name_equal(&gl->gl_name, name))
+			continue;
+		if (gl->gl_sbd != sdp)
+			continue;
+		if (lockref_get_not_dead(&gl->gl_lockref))
+			return gl;
+	}
+
+	return NULL;
+}
+
+/**
+ * may_grant - check if its ok to grant a new lock
+ * @gl: The glock
+ * @gh: The lock request which we wish to grant
+ *
+ * Returns: true if its ok to grant the lock
+ */
+
+static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
+{
+	const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
+	if ((gh->gh_state == LM_ST_EXCLUSIVE ||
+	     gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
+		return 0;
+	if (gl->gl_state == gh->gh_state)
+		return 1;
+	if (gh->gh_flags & GL_EXACT)
+		return 0;
+	if (gl->gl_state == LM_ST_EXCLUSIVE) {
+		if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
+			return 1;
+		if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
+			return 1;
+	}
+	if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
+		return 1;
+	return 0;
+}
+
+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);
+}
+
+/**
+ * do_error - Something unexpected has happened during a lock request
+ *
+ */
+
+static inline 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_HOLDER, &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);
+	}
+}
+
+/**
+ * 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, or 2
+ *          if a type specific operation is underway.
+ */
+
+static int do_promote(struct gfs2_glock *gl)
+__releases(&gl->gl_spin)
+__acquires(&gl->gl_spin)
+{
+	const struct gfs2_glock_operations *glops = gl->gl_ops;
+	struct gfs2_holder *gh, *tmp;
+	int ret;
+
+restart:
+	list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
+		if (test_bit(HIF_HOLDER, &gh->gh_iflags))
+			continue;
+		if (may_grant(gl, gh)) {
+			if (gh->gh_list.prev == &gl->gl_holders &&
+			    glops->go_lock) {
+				spin_unlock(&gl->gl_spin);
+				/* FIXME: eliminate this eventually */
+				ret = glops->go_lock(gh);
+				spin_lock(&gl->gl_spin);
+				if (ret) {
+					if (ret == 1)
+						return 2;
+					gh->gh_error = ret;
+					list_del_init(&gh->gh_list);
+					trace_gfs2_glock_queue(gh, 0);
+					gfs2_holder_wake(gh);
+					goto restart;
+				}
+				set_bit(HIF_HOLDER, &gh->gh_iflags);
+				trace_gfs2_promote(gh, 1);
+				gfs2_holder_wake(gh);
+				goto restart;
+			}
+			set_bit(HIF_HOLDER, &gh->gh_iflags);
+			trace_gfs2_promote(gh, 0);
+			gfs2_holder_wake(gh);
+			continue;
+		}
+		if (gh->gh_list.prev == &gl->gl_holders)
+			return 1;
+		do_error(gl, 0);
+		break;
+	}
+	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 (held1 && held2 && list_empty(&gl->gl_holders))
+		clear_bit(GLF_QUEUED, &gl->gl_flags);
+
+	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_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;
+	int rv;
+
+	spin_lock(&gl->gl_spin);
+	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 && !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 */
+			pr_err("wanted %u got %u\n", gl->gl_target, state);
+			GLOCK_BUG_ON(gl, 1);
+		}
+		spin_unlock(&gl->gl_spin);
+		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) {
+			spin_unlock(&gl->gl_spin);
+			rv = glops->go_xmote_bh(gl, gh);
+			spin_lock(&gl->gl_spin);
+			if (rv) {
+				do_error(gl, rv);
+				goto out;
+			}
+		}
+		rv = do_promote(gl);
+		if (rv == 2)
+			goto out_locked;
+	}
+out:
+	clear_bit(GLF_LOCK, &gl->gl_flags);
+out_locked:
+	spin_unlock(&gl->gl_spin);
+}
+
+/**
+ * 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_spin)
+__acquires(&gl->gl_spin)
+{
+	const struct gfs2_glock_operations *glops = gl->gl_ops;
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	unsigned int lck_flags = gh ? gh->gh_flags : 0;
+	int ret;
+
+	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) {
+		set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
+		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_spin);
+	if (glops->go_sync)
+		glops->go_sync(gl);
+	if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
+		glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
+	clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
+
+	gfs2_glock_hold(gl);
+	if (sdp->sd_lockstruct.ls_ops->lm_lock)	{
+		/* lock_dlm */
+		ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
+		if (ret) {
+			pr_err("lm_lock ret %d\n", ret);
+			GLOCK_BUG_ON(gl, 1);
+		}
+	} else { /* lock_nolock */
+		finish_xmote(gl, target);
+		if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
+			gfs2_glock_put(gl);
+	}
+
+	spin_lock(&gl->gl_spin);
+}
+
+/**
+ * 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_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
+		if (test_bit(HIF_HOLDER, &gh->gh_iflags))
+			return gh;
+	}
+	return NULL;
+}
+
+/**
+ * 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_spin)
+__acquires(&gl->gl_spin)
+{
+	struct gfs2_holder *gh = NULL;
+	int ret;
+
+	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);
+		ret = do_promote(gl);
+		if (ret == 0)
+			goto out_unlock;
+		if (ret == 2)
+			goto out;
+		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);
+out:
+	return;
+
+out_sched:
+	clear_bit(GLF_LOCK, &gl->gl_flags);
+	smp_mb__after_atomic();
+	gl->gl_lockref.count++;
+	if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
+		gl->gl_lockref.count--;
+	return;
+
+out_unlock:
+	clear_bit(GLF_LOCK, &gl->gl_flags);
+	smp_mb__after_atomic();
+	return;
+}
+
+static void delete_work_func(struct work_struct *work)
+{
+	struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct gfs2_inode *ip;
+	struct inode *inode;
+	u64 no_addr = gl->gl_name.ln_number;
+
+	ip = gl->gl_object;
+	/* Note: Unsafe to dereference ip as we don't hold right refs/locks */
+
+	if (ip)
+		inode = gfs2_ilookup(sdp->sd_vfs, no_addr, 1);
+	else
+		inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
+	if (inode && !IS_ERR(inode)) {
+		d_prune_aliases(inode);
+		iput(inode);
+	}
+	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);
+	int drop_ref = 0;
+
+	if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
+		finish_xmote(gl, gl->gl_reply);
+		drop_ref = 1;
+	}
+	spin_lock(&gl->gl_spin);
+	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);
+			set_bit(GLF_DEMOTE, &gl->gl_flags);
+		}
+	}
+	run_queue(gl, 0);
+	spin_unlock(&gl->gl_spin);
+	if (!delay)
+		gfs2_glock_put(gl);
+	else {
+		if (gl->gl_name.ln_type != LM_TYPE_INODE)
+			delay = 0;
+		if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
+			gfs2_glock_put(gl);
+	}
+	if (drop_ref)
+		gfs2_glock_put(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 };
+	struct gfs2_glock *gl, *tmp;
+	unsigned int hash = gl_hash(sdp, &name);
+	struct address_space *mapping;
+	struct kmem_cache *cachep;
+
+	rcu_read_lock();
+	gl = search_bucket(hash, sdp, &name);
+	rcu_read_unlock();
+
+	*glp = gl;
+	if (gl)
+		return 0;
+	if (!create)
+		return -ENOENT;
+
+	if (glops->go_flags & GLOF_ASPACE)
+		cachep = gfs2_glock_aspace_cachep;
+	else
+		cachep = gfs2_glock_cachep;
+	gl = kmem_cache_alloc(cachep, GFP_NOFS);
+	if (!gl)
+		return -ENOMEM;
+
+	memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
+
+	if (glops->go_flags & GLOF_LVB) {
+		gl->gl_lksb.sb_lvbptr = kzalloc(GFS2_MIN_LVB_SIZE, GFP_NOFS);
+		if (!gl->gl_lksb.sb_lvbptr) {
+			kmem_cache_free(cachep, gl);
+			return -ENOMEM;
+		}
+	}
+
+	atomic_inc(&sdp->sd_glock_disposal);
+	gl->gl_sbd = sdp;
+	gl->gl_flags = 0;
+	gl->gl_name = name;
+	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_hash = hash;
+	gl->gl_ops = glops;
+	gl->gl_dstamp = ktime_set(0, 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);
+	INIT_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;
+	}
+
+	spin_lock_bucket(hash);
+	tmp = search_bucket(hash, sdp, &name);
+	if (tmp) {
+		spin_unlock_bucket(hash);
+		kfree(gl->gl_lksb.sb_lvbptr);
+		kmem_cache_free(cachep, gl);
+		atomic_dec(&sdp->sd_glock_disposal);
+		gl = tmp;
+	} else {
+		hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
+		spin_unlock_bucket(hash);
+	}
+
+	*glp = gl;
+
+	return 0;
+}
+
+/**
+ * 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, unsigned flags,
+		      struct gfs2_holder *gh)
+{
+	INIT_LIST_HEAD(&gh->gh_list);
+	gh->gh_gl = gl;
+	gh->gh_ip = _RET_IP_;
+	gh->gh_owner_pid = get_pid(task_pid(current));
+	gh->gh_state = state;
+	gh->gh_flags = flags;
+	gh->gh_error = 0;
+	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, unsigned 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);
+	gh->gh_gl = NULL;
+	gh->gh_ip = 0;
+}
+
+/**
+ * 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 time1 = jiffies;
+
+	might_sleep();
+	wait_on_bit(&gh->gh_iflags, HIF_WAIT, TASK_UNINTERRUPTIBLE);
+	if (time_after(jiffies, time1 + HZ)) /* have we waited > a second? */
+		/* Lengthen the minimum hold time. */
+		gh->gh_gl->gl_hold_time = min(gh->gh_gl->gl_hold_time +
+					      GL_GLOCK_HOLD_INCR,
+					      GL_GLOCK_MAX_HOLD);
+	return gh->gh_error;
+}
+
+/**
+ * handle_callback - process a demote request
+ * @gl: the glock
+ * @state: the state the caller wants us to change to
+ *
+ * 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)
+{
+	int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
+
+	set_bit(bit, &gl->gl_flags);
+	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_spin)
+__acquires(&gl->gl_spin)
+{
+	struct gfs2_glock *gl = gh->gh_gl;
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct list_head *insert_pt = NULL;
+	struct gfs2_holder *gh2;
+	int try_futile = 0;
+
+	BUG_ON(gh->gh_owner_pid == NULL);
+	if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
+		BUG();
+
+	if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
+		if (test_bit(GLF_LOCK, &gl->gl_flags))
+			try_futile = !may_grant(gl, 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)))
+			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;
+	}
+	set_bit(GLF_QUEUED, &gl->gl_flags);
+	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_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
+	if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
+		spin_unlock(&gl->gl_spin);
+		if (sdp->sd_lockstruct.ls_ops->lm_cancel)
+			sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
+		spin_lock(&gl->gl_spin);
+	}
+	return;
+
+trap_recursive:
+	pr_err("original: %pSR\n", (void *)gh2->gh_ip);
+	pr_err("pid: %d\n", pid_nr(gh2->gh_owner_pid));
+	pr_err("lock type: %d req lock state : %d\n",
+	       gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
+	pr_err("new: %pSR\n", (void *)gh->gh_ip);
+	pr_err("pid: %d\n", pid_nr(gh->gh_owner_pid));
+	pr_err("lock type: %d req lock state : %d\n",
+	       gh->gh_gl->gl_name.ln_type, gh->gh_state);
+	gfs2_dump_glock(NULL, gl);
+	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;
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	int error = 0;
+
+	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
+		return -EIO;
+
+	if (test_bit(GLF_LRU, &gl->gl_flags))
+		gfs2_glock_remove_from_lru(gl);
+
+	spin_lock(&gl->gl_spin);
+	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++;
+		if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
+			gl->gl_lockref.count--;
+	}
+	run_queue(gl, 1);
+	spin_unlock(&gl->gl_spin);
+
+	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;
+}
+
+/**
+ * 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;
+	const struct gfs2_glock_operations *glops = gl->gl_ops;
+	unsigned delay = 0;
+	int fast_path = 0;
+
+	spin_lock(&gl->gl_spin);
+	if (gh->gh_flags & GL_NOCACHE)
+		handle_callback(gl, LM_ST_UNLOCKED, 0, false);
+
+	list_del_init(&gh->gh_list);
+	if (find_first_holder(gl) == NULL) {
+		if (glops->go_unlock) {
+			GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
+			spin_unlock(&gl->gl_spin);
+			glops->go_unlock(gh);
+			spin_lock(&gl->gl_spin);
+			clear_bit(GLF_LOCK, &gl->gl_flags);
+		}
+		if (list_empty(&gl->gl_holders) &&
+		    !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
+		    !test_bit(GLF_DEMOTE, &gl->gl_flags))
+			fast_path = 1;
+	}
+	if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl))
+		gfs2_glock_add_to_lru(gl);
+
+	trace_gfs2_glock_queue(gh, 0);
+	spin_unlock(&gl->gl_spin);
+	if (likely(fast_path))
+		return;
+
+	gfs2_glock_hold(gl);
+	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;
+	if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
+		gfs2_glock_put(gl);
+}
+
+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, int 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 - synchonously acquire more than one glock in deadlock free order
+ * @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)
+ */
+
+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++) {
+		p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
+
+		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:
+		ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
+		return gfs2_glock_nq(ghs);
+	default:
+		if (num_gh <= 4)
+			break;
+		pph = kmalloc(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);
+	holdtime = gl->gl_tchange + gl->gl_hold_time;
+	if (test_bit(GLF_QUEUED, &gl->gl_flags) &&
+	    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;
+	}
+
+	spin_lock(&gl->gl_spin);
+	handle_callback(gl, state, delay, true);
+	spin_unlock(&gl->gl_spin);
+	if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
+		gfs2_glock_put(gl);
+}
+
+/**
+ * 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_spin 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_sbd->sd_lockstruct;
+
+	spin_lock(&gl->gl_spin);
+	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_spin);
+			return;
+		}
+	}
+
+	gl->gl_lockref.count++;
+	set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
+	spin_unlock(&gl->gl_spin);
+
+	if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
+		gfs2_glock_put(gl);
+}
+
+static int glock_cmp(void *priv, struct list_head *a, 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_entry(list->next, struct gfs2_glock, gl_lru);
+		list_del_init(&gl->gl_lru);
+		if (!spin_trylock(&gl->gl_spin)) {
+add_back_to_lru:
+			list_add(&gl->gl_lru, &lru_list);
+			atomic_inc(&lru_count);
+			continue;
+		}
+		if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
+			spin_unlock(&gl->gl_spin);
+			goto add_back_to_lru;
+		}
+		clear_bit(GLF_LRU, &gl->gl_flags);
+		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));
+		if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
+			gl->gl_lockref.count--;
+		spin_unlock(&gl->gl_spin);
+		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_entry(lru_list.next, 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,
+};
+
+/**
+ * examine_bucket - Call a function for glock in a hash bucket
+ * @examiner: the function
+ * @sdp: the filesystem
+ * @bucket: the bucket
+ *
+ */
+
+static void examine_bucket(glock_examiner examiner, const struct gfs2_sbd *sdp,
+			  unsigned int hash)
+{
+	struct gfs2_glock *gl;
+	struct hlist_bl_head *head = &gl_hash_table[hash];
+	struct hlist_bl_node *pos;
+
+	rcu_read_lock();
+	hlist_bl_for_each_entry_rcu(gl, pos, head, gl_list) {
+		if ((gl->gl_sbd == sdp) && lockref_get_not_dead(&gl->gl_lockref))
+			examiner(gl);
+	}
+	rcu_read_unlock();
+	cond_resched();
+}
+
+static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
+{
+	unsigned x;
+
+	for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
+		examine_bucket(examiner, sdp, x);
+}
+
+
+/**
+ * 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))
+		goto out;
+	set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
+	if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0) {
+out:
+		gfs2_glock_put(gl);
+	}
+}
+
+/**
+ * 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_spin);
+	if (gl->gl_state != LM_ST_UNLOCKED)
+		handle_callback(gl, LM_ST_UNLOCKED, 0, false);
+	spin_unlock(&gl->gl_spin);
+	if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
+		gfs2_glock_put(gl);
+}
+
+/**
+ * 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)
+{
+	spin_lock(&gl->gl_spin);
+	gfs2_dump_glock(seq, gl);
+	spin_unlock(&gl->gl_spin);
+}
+
+static void dump_glock_func(struct gfs2_glock *gl)
+{
+	dump_glock(NULL, gl);
+}
+
+/**
+ * gfs2_gl_hash_clear - Empty out the glock hash table
+ * @sdp: the filesystem
+ * @wait: wait until it's all gone
+ *
+ * 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(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
+	glock_hash_walk(dump_glock_func, sdp);
+}
+
+void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
+{
+	struct gfs2_glock *gl = ip->i_gl;
+	int ret;
+
+	ret = gfs2_truncatei_resume(ip);
+	gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
+
+	spin_lock(&gl->gl_spin);
+	clear_bit(GLF_LOCK, &gl->gl_flags);
+	run_queue(gl, 1);
+	spin_unlock(&gl->gl_spin);
+}
+
+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, unsigned 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 & 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_FIRST, &iflags))
+		*p++ = 'F';
+	*p = 0;
+	return buf;
+}
+
+/**
+ * dump_holder - print information about a glock holder
+ * @seq: the seq_file struct
+ * @gh: the glock holder
+ *
+ */
+
+static void dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
+{
+	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, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
+		       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 (test_bit(GLF_QUEUED, gflags))
+		*p++ = 'q';
+	if (test_bit(GLF_LRU, gflags))
+		*p++ = 'L';
+	if (gl->gl_object)
+		*p++ = 'o';
+	if (test_bit(GLF_BLOCKING, gflags))
+		*p++ = 'b';
+	*p = 0;
+	return buf;
+}
+
+/**
+ * gfs2_dump_glock - print information about a glock
+ * @seq: The seq_file struct
+ * @gl: the glock
+ *
+ * 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, const struct gfs2_glock *gl)
+{
+	const struct gfs2_glock_operations *glops = gl->gl_ops;
+	unsigned long long dtime;
+	const struct gfs2_holder *gh;
+	char gflags_buf[32];
+
+	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, "G:  s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d v:%d r:%d m:%ld\n",
+		  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);
+
+	list_for_each_entry(gh, &gl->gl_holders, gh_list)
+		dump_holder(seq, gh);
+
+	if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
+		glops->go_dump(seq, gl);
+}
+
+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:%lld/%lld rttb:%lld/%lld irt:%lld/%lld dcnt: %lld qcnt: %lld\n",
+		   gl->gl_name.ln_type,
+		   (unsigned long long)gl->gl_name.ln_number,
+		   (long long)gl->gl_stats.stats[GFS2_LKS_SRTT],
+		   (long long)gl->gl_stats.stats[GFS2_LKS_SRTTVAR],
+		   (long long)gl->gl_stats.stats[GFS2_LKS_SRTTB],
+		   (long long)gl->gl_stats.stats[GFS2_LKS_SRTTVARB],
+		   (long long)gl->gl_stats.stats[GFS2_LKS_SIRT],
+		   (long long)gl->gl_stats.stats[GFS2_LKS_SIRTVAR],
+		   (long long)gl->gl_stats.stats[GFS2_LKS_DCOUNT],
+		   (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_glock_iter *gi = seq->private;
+	struct gfs2_sbd *sdp = gi->sdp;
+	unsigned index = gi->hash >> 3;
+	unsigned subindex = gi->hash & 0x07;
+	s64 value;
+	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) {
+			value = i;
+		} else {
+			value = lkstats->lkstats[index - 1].stats[subindex];
+		}
+		seq_printf(seq, " %15lld", (long long)value);
+	}
+	seq_putc(seq, '\n');
+	return 0;
+}
+
+int __init gfs2_glock_init(void)
+{
+	unsigned i;
+	for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
+		INIT_HLIST_BL_HEAD(&gl_hash_table[i]);
+	}
+
+	glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
+					  WQ_HIGHPRI | WQ_FREEZABLE, 0);
+	if (!glock_workqueue)
+		return -ENOMEM;
+	gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
+						WQ_MEM_RECLAIM | WQ_FREEZABLE,
+						0);
+	if (!gfs2_delete_workqueue) {
+		destroy_workqueue(glock_workqueue);
+		return -ENOMEM;
+	}
+
+	register_shrinker(&glock_shrinker);
+
+	return 0;
+}
+
+void gfs2_glock_exit(void)
+{
+	unregister_shrinker(&glock_shrinker);
+	destroy_workqueue(glock_workqueue);
+	destroy_workqueue(gfs2_delete_workqueue);
+}
+
+static inline struct gfs2_glock *glock_hash_chain(unsigned hash)
+{
+	return hlist_bl_entry(hlist_bl_first_rcu(&gl_hash_table[hash]),
+			      struct gfs2_glock, gl_list);
+}
+
+static inline struct gfs2_glock *glock_hash_next(struct gfs2_glock *gl)
+{
+	return hlist_bl_entry(rcu_dereference(gl->gl_list.next),
+			      struct gfs2_glock, gl_list);
+}
+
+static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
+{
+	struct gfs2_glock *gl;
+
+	do {
+		gl = gi->gl;
+		if (gl) {
+			gi->gl = glock_hash_next(gl);
+			gi->nhash++;
+		} else {
+			if (gi->hash >= GFS2_GL_HASH_SIZE) {
+				rcu_read_unlock();
+				return 1;
+			}
+			gi->gl = glock_hash_chain(gi->hash);
+			gi->nhash = 0;
+		}
+		while (gi->gl == NULL) {
+			gi->hash++;
+			if (gi->hash >= GFS2_GL_HASH_SIZE) {
+				rcu_read_unlock();
+				return 1;
+			}
+			gi->gl = glock_hash_chain(gi->hash);
+			gi->nhash = 0;
+		}
+	/* Skip entries for other sb and dead entries */
+	} while (gi->sdp != gi->gl->gl_sbd ||
+		 __lockref_is_dead(&gi->gl->gl_lockref));
+
+	return 0;
+}
+
+static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	struct gfs2_glock_iter *gi = seq->private;
+	loff_t n = *pos;
+
+	if (gi->last_pos <= *pos)
+		n = gi->nhash + (*pos - gi->last_pos);
+	else
+		gi->hash = 0;
+
+	gi->nhash = 0;
+	rcu_read_lock();
+
+	do {
+		if (gfs2_glock_iter_next(gi))
+			return NULL;
+	} while (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;
+	if (gfs2_glock_iter_next(gi))
+		return NULL;
+
+	return gi->gl;
+}
+
+static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
+{
+	struct gfs2_glock_iter *gi = seq->private;
+
+	if (gi->gl)
+		rcu_read_unlock();
+	gi->gl = NULL;
+}
+
+static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
+{
+	dump_glock(seq, iter_ptr);
+	return 0;
+}
+
+static void *gfs2_sbstats_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	struct gfs2_glock_iter *gi = seq->private;
+
+	gi->hash = *pos;
+	if (*pos >= GFS2_NR_SBSTATS)
+		return NULL;
+	preempt_disable();
+	return SEQ_START_TOKEN;
+}
+
+static void *gfs2_sbstats_seq_next(struct seq_file *seq, void *iter_ptr,
+				   loff_t *pos)
+{
+	struct gfs2_glock_iter *gi = seq->private;
+	(*pos)++;
+	gi->hash++;
+	if (gi->hash >= GFS2_NR_SBSTATS) {
+		preempt_enable();
+		return NULL;
+	}
+	return SEQ_START_TOKEN;
+}
+
+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_seq_ops = {
+	.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)
+{
+	int ret = seq_open_private(file, &gfs2_glock_seq_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;
+	}
+	return ret;
+}
+
+static int gfs2_glstats_open(struct inode *inode, struct file *file)
+{
+	int ret = seq_open_private(file, &gfs2_glstats_seq_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;
+	}
+	return ret;
+}
+
+static int gfs2_sbstats_open(struct inode *inode, struct file *file)
+{
+	int ret = seq_open_private(file, &gfs2_sbstats_seq_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;
+	}
+	return ret;
+}
+
+static const struct file_operations gfs2_glocks_fops = {
+	.owner   = THIS_MODULE,
+	.open    = gfs2_glocks_open,
+	.read    = seq_read,
+	.llseek  = seq_lseek,
+	.release = seq_release_private,
+};
+
+static const struct file_operations gfs2_glstats_fops = {
+	.owner   = THIS_MODULE,
+	.open    = gfs2_glstats_open,
+	.read    = seq_read,
+	.llseek  = seq_lseek,
+	.release = seq_release_private,
+};
+
+static const struct file_operations gfs2_sbstats_fops = {
+	.owner   = THIS_MODULE,
+	.open	 = gfs2_sbstats_open,
+	.read    = seq_read,
+	.llseek  = seq_lseek,
+	.release = seq_release_private,
+};
+
+int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
+{
+	struct dentry *dent;
+
+	dent = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
+	if (IS_ERR_OR_NULL(dent))
+		goto fail;
+	sdp->debugfs_dir = dent;
+
+	dent = debugfs_create_file("glocks",
+				   S_IFREG | S_IRUGO,
+				   sdp->debugfs_dir, sdp,
+				   &gfs2_glocks_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto fail;
+	sdp->debugfs_dentry_glocks = dent;
+
+	dent = debugfs_create_file("glstats",
+				   S_IFREG | S_IRUGO,
+				   sdp->debugfs_dir, sdp,
+				   &gfs2_glstats_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto fail;
+	sdp->debugfs_dentry_glstats = dent;
+
+	dent = debugfs_create_file("sbstats",
+				   S_IFREG | S_IRUGO,
+				   sdp->debugfs_dir, sdp,
+				   &gfs2_sbstats_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto fail;
+	sdp->debugfs_dentry_sbstats = dent;
+
+	return 0;
+fail:
+	gfs2_delete_debugfs_file(sdp);
+	return dent ? PTR_ERR(dent) : -ENOMEM;
+}
+
+void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
+{
+	if (sdp->debugfs_dir) {
+		if (sdp->debugfs_dentry_glocks) {
+			debugfs_remove(sdp->debugfs_dentry_glocks);
+			sdp->debugfs_dentry_glocks = NULL;
+		}
+		if (sdp->debugfs_dentry_glstats) {
+			debugfs_remove(sdp->debugfs_dentry_glstats);
+			sdp->debugfs_dentry_glstats = NULL;
+		}
+		if (sdp->debugfs_dentry_sbstats) {
+			debugfs_remove(sdp->debugfs_dentry_sbstats);
+			sdp->debugfs_dentry_sbstats = NULL;
+		}
+		debugfs_remove(sdp->debugfs_dir);
+		sdp->debugfs_dir = NULL;
+	}
+}
+
+int gfs2_register_debugfs(void)
+{
+	gfs2_root = debugfs_create_dir("gfs2", NULL);
+	if (IS_ERR(gfs2_root))
+		return PTR_ERR(gfs2_root);
+	return gfs2_root ? 0 : -ENOMEM;
+}
+
+void gfs2_unregister_debugfs(void)
+{
+	debugfs_remove(gfs2_root);
+	gfs2_root = NULL;
+}