GFS: locking

@@ -0,0 +1,2535 @@
+/*
+ * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
+ * Copyright (C) 2004-2005 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 v.2.
+ */
+
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/completion.h>
+#include <linux/buffer_head.h>
+#include <linux/delay.h>
+#include <linux/sort.h>
+#include <linux/jhash.h>
+#include <linux/kref.h>
+#include <asm/semaphore.h>
+#include <asm/uaccess.h>
+
+#include "gfs2.h"
+#include "glock.h"
+#include "glops.h"
+#include "inode.h"
+#include "lm.h"
+#include "lops.h"
+#include "meta_io.h"
+#include "quota.h"
+#include "super.h"
+
+/*  Must be kept in sync with the beginning of struct gfs2_glock  */
+struct glock_plug {
+	struct list_head gl_list;
+	unsigned long gl_flags;
+};
+
+struct greedy {
+	struct gfs2_holder gr_gh;
+	struct work_struct gr_work;
+};
+
+typedef void (*glock_examiner) (struct gfs2_glock * gl);
+
+/**
+ * relaxed_state_ok - is a requested lock compatible with the current lock mode?
+ * @actual: the current state of the lock
+ * @requested: the lock state that was requested by the caller
+ * @flags: the modifier flags passed in by the caller
+ *
+ * Returns: 1 if the locks are compatible, 0 otherwise
+ */
+
+static inline int relaxed_state_ok(unsigned int actual, unsigned requested,
+				   int flags)
+{
+	if (actual == requested)
+		return 1;
+
+	if (flags & GL_EXACT)
+		return 0;
+
+	if (actual == LM_ST_EXCLUSIVE && requested == LM_ST_SHARED)
+		return 1;
+
+	if (actual != LM_ST_UNLOCKED && (flags & LM_FLAG_ANY))
+		return 1;
+
+	return 0;
+}
+
+/**
+ * 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(struct lm_lockname *name)
+{
+	unsigned int h;
+
+	h = jhash(&name->ln_number, sizeof(uint64_t), 0);
+	h = jhash(&name->ln_type, sizeof(unsigned int), h);
+	h &= GFS2_GL_HASH_MASK;
+
+	return h;
+}
+
+/**
+ * glock_free() - Perform a few checks and then release struct gfs2_glock
+ * @gl: The glock to release
+ *
+ * Also calls lock module to release its internal structure for this glock.
+ *
+ */
+
+static void glock_free(struct gfs2_glock *gl)
+{
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct inode *aspace = gl->gl_aspace;
+
+	gfs2_lm_put_lock(sdp, gl->gl_lock);
+
+	if (aspace)
+		gfs2_aspace_put(aspace);
+
+	kmem_cache_free(gfs2_glock_cachep, gl);
+
+	atomic_dec(&sdp->sd_glock_count);
+}
+
+/**
+ * gfs2_glock_hold() - increment reference count on glock
+ * @gl: The glock to hold
+ *
+ */
+
+void gfs2_glock_hold(struct gfs2_glock *gl)
+{
+	kref_get(&gl->gl_ref);
+}
+
+/* All work is done after the return from kref_put() so we
+   can release the write_lock before the free. */
+
+static void kill_glock(struct kref *kref)
+{
+	struct gfs2_glock *gl = container_of(kref, struct gfs2_glock, gl_ref);
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+
+	gfs2_assert(sdp, gl->gl_state == LM_ST_UNLOCKED);
+	gfs2_assert(sdp, list_empty(&gl->gl_reclaim));
+	gfs2_assert(sdp, list_empty(&gl->gl_holders));
+	gfs2_assert(sdp, list_empty(&gl->gl_waiters1));
+	gfs2_assert(sdp, list_empty(&gl->gl_waiters2));
+	gfs2_assert(sdp, list_empty(&gl->gl_waiters3));
+}
+
+/**
+ * gfs2_glock_put() - Decrement reference count on glock
+ * @gl: The glock to put
+ *
+ */
+
+int gfs2_glock_put(struct gfs2_glock *gl)
+{
+	struct gfs2_gl_hash_bucket *bucket = gl->gl_bucket;
+
+	write_lock(&bucket->hb_lock);
+	if (kref_put(&gl->gl_ref, kill_glock)) {
+		list_del_init(&gl->gl_list);
+		write_unlock(&bucket->hb_lock);
+		glock_free(gl);
+		return 1;
+	}
+	write_unlock(&bucket->hb_lock);
+	return 0;
+}
+
+/**
+ * queue_empty - check to see if a glock's queue is empty
+ * @gl: the glock
+ * @head: the head of the queue to check
+ *
+ * This function protects the list in the event that a process already
+ * has a holder on the list and is adding a second holder for itself.
+ * The glmutex lock is what generally prevents processes from working
+ * on the same glock at once, but the special case of adding a second
+ * holder for yourself ("recursive" locking) doesn't involve locking
+ * glmutex, making the spin lock necessary.
+ *
+ * Returns: 1 if the queue is empty
+ */
+
+static inline int queue_empty(struct gfs2_glock *gl, struct list_head *head)
+{
+	int empty;
+	spin_lock(&gl->gl_spin);
+	empty = list_empty(head);
+	spin_unlock(&gl->gl_spin);
+	return empty;
+}
+
+/**
+ * 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(struct gfs2_gl_hash_bucket *bucket,
+					struct lm_lockname *name)
+{
+	struct gfs2_glock *gl;
+
+	list_for_each_entry(gl, &bucket->hb_list, gl_list) {
+		if (test_bit(GLF_PLUG, &gl->gl_flags))
+			continue;
+		if (!lm_name_equal(&gl->gl_name, name))
+			continue;
+
+		kref_get(&gl->gl_ref);
+
+		return gl;
+	}
+
+	return NULL;
+}
+
+/**
+ * gfs2_glock_find() - Find glock by lock number
+ * @sdp: The GFS2 superblock
+ * @name: The lock name
+ *
+ * Returns: NULL, or the struct gfs2_glock with the requested number
+ */
+
+struct gfs2_glock *gfs2_glock_find(struct gfs2_sbd *sdp,
+				   struct lm_lockname *name)
+{
+	struct gfs2_gl_hash_bucket *bucket = &sdp->sd_gl_hash[gl_hash(name)];
+	struct gfs2_glock *gl;
+
+	read_lock(&bucket->hb_lock);
+	gl = search_bucket(bucket, name);
+	read_unlock(&bucket->hb_lock);
+
+	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, uint64_t number,
+		   struct gfs2_glock_operations *glops, int create,
+		   struct gfs2_glock **glp)
+{
+	struct lm_lockname name;
+	struct gfs2_glock *gl, *tmp;
+	struct gfs2_gl_hash_bucket *bucket;
+	int error;
+
+	name.ln_number = number;
+	name.ln_type = glops->go_type;
+	bucket = &sdp->sd_gl_hash[gl_hash(&name)];
+
+	read_lock(&bucket->hb_lock);
+	gl = search_bucket(bucket, &name);
+	read_unlock(&bucket->hb_lock);
+
+	if (gl || !create) {
+		*glp = gl;
+		return 0;
+	}
+
+	gl = kmem_cache_alloc(gfs2_glock_cachep, GFP_KERNEL);
+	if (!gl)
+		return -ENOMEM;
+
+	memset(gl, 0, sizeof(struct gfs2_glock));
+
+	INIT_LIST_HEAD(&gl->gl_list);
+	gl->gl_name = name;
+	kref_init(&gl->gl_ref);
+
+	spin_lock_init(&gl->gl_spin);
+
+	gl->gl_state = LM_ST_UNLOCKED;
+	INIT_LIST_HEAD(&gl->gl_holders);
+	INIT_LIST_HEAD(&gl->gl_waiters1);
+	INIT_LIST_HEAD(&gl->gl_waiters2);
+	INIT_LIST_HEAD(&gl->gl_waiters3);
+
+	gl->gl_ops = glops;
+
+	gl->gl_bucket = bucket;
+	INIT_LIST_HEAD(&gl->gl_reclaim);
+
+	gl->gl_sbd = sdp;
+
+	lops_init_le(&gl->gl_le, &gfs2_glock_lops);
+	INIT_LIST_HEAD(&gl->gl_ail_list);
+
+	/* If this glock protects actual on-disk data or metadata blocks,
+	   create a VFS inode to manage the pages/buffers holding them. */
+	if (glops == &gfs2_inode_glops ||
+	    glops == &gfs2_rgrp_glops ||
+	    glops == &gfs2_meta_glops) {
+		gl->gl_aspace = gfs2_aspace_get(sdp);
+		if (!gl->gl_aspace) {
+			error = -ENOMEM;
+			goto fail;
+		}
+	}
+
+	error = gfs2_lm_get_lock(sdp, &name, &gl->gl_lock);
+	if (error)
+		goto fail_aspace;
+
+	atomic_inc(&sdp->sd_glock_count);
+
+	write_lock(&bucket->hb_lock);
+	tmp = search_bucket(bucket, &name);
+	if (tmp) {
+		write_unlock(&bucket->hb_lock);
+		glock_free(gl);
+		gl = tmp;
+	} else {
+		list_add_tail(&gl->gl_list, &bucket->hb_list);
+		write_unlock(&bucket->hb_lock);
+	}
+
+	*glp = gl;
+
+	return 0;
+
+ fail_aspace:
+	if (gl->gl_aspace)
+		gfs2_aspace_put(gl->gl_aspace);
+
+ fail:
+	kmem_cache_free(gfs2_glock_cachep, gl);	
+
+	return error;
+}
+
+/**
+ * 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, int flags,
+		      struct gfs2_holder *gh)
+{
+	INIT_LIST_HEAD(&gh->gh_list);
+	gh->gh_gl = gl;
+	gh->gh_owner = (flags & GL_NEVER_RECURSE) ? NULL : current;
+	gh->gh_state = state;
+	gh->gh_flags = flags;
+	gh->gh_error = 0;
+	gh->gh_iflags = 0;
+	init_completion(&gh->gh_wait);
+
+	if (gh->gh_state == LM_ST_EXCLUSIVE)
+		gh->gh_flags |= GL_LOCAL_EXCL;
+
+	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, int flags, struct gfs2_holder *gh)
+{
+	gh->gh_state = state;
+	gh->gh_flags = flags;
+	if (gh->gh_state == LM_ST_EXCLUSIVE)
+		gh->gh_flags |= GL_LOCAL_EXCL;
+
+	gh->gh_iflags &= 1 << HIF_ALLOCED;
+}
+
+/**
+ * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
+ * @gh: the holder structure
+ *
+ */
+
+void gfs2_holder_uninit(struct gfs2_holder *gh)
+{
+	gfs2_glock_put(gh->gh_gl);
+	gh->gh_gl = NULL;
+}
+
+/**
+ * gfs2_holder_get - get a struct gfs2_holder structure
+ * @gl: the glock
+ * @state: the state we're requesting
+ * @flags: the modifier flags
+ * @gfp_flags: __GFP_NOFAIL
+ *
+ * Figure out how big an impact this function has.  Either:
+ * 1) Replace it with a cache of structures hanging off the struct gfs2_sbd
+ * 2) Leave it like it is
+ *
+ * Returns: the holder structure, NULL on ENOMEM
+ */
+
+struct gfs2_holder *gfs2_holder_get(struct gfs2_glock *gl, unsigned int state,
+				    int flags, int gfp_flags)
+{
+	struct gfs2_holder *gh;
+
+	gh = kmalloc(sizeof(struct gfs2_holder), gfp_flags);
+	if (!gh)
+		return NULL;
+
+	gfs2_holder_init(gl, state, flags, gh);
+	set_bit(HIF_ALLOCED, &gh->gh_iflags);
+
+	return gh;
+}
+
+/**
+ * gfs2_holder_put - get rid of a struct gfs2_holder structure
+ * @gh: the holder structure
+ *
+ */
+
+void gfs2_holder_put(struct gfs2_holder *gh)
+{
+	gfs2_holder_uninit(gh);
+	kfree(gh);
+}
+
+/**
+ * handle_recurse - put other holder structures (marked recursive)
+ *                  into the holders list
+ * @gh: the holder structure
+ *
+ */
+
+static void handle_recurse(struct gfs2_holder *gh)
+{
+	struct gfs2_glock *gl = gh->gh_gl;
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct gfs2_holder *tmp_gh, *safe;
+	int found = 0;
+
+	if (gfs2_assert_warn(sdp, gh->gh_owner))
+		return;
+
+	list_for_each_entry_safe(tmp_gh, safe, &gl->gl_waiters3, gh_list) {
+		if (tmp_gh->gh_owner != gh->gh_owner)
+			continue;
+
+		gfs2_assert_warn(sdp,
+				 test_bit(HIF_RECURSE, &tmp_gh->gh_iflags));
+
+		list_move_tail(&tmp_gh->gh_list, &gl->gl_holders);
+		tmp_gh->gh_error = 0;
+		set_bit(HIF_HOLDER, &tmp_gh->gh_iflags);
+
+		complete(&tmp_gh->gh_wait);
+
+		found = 1;
+	}
+
+	gfs2_assert_warn(sdp, found);
+}
+
+/**
+ * do_unrecurse - a recursive holder was just dropped of the waiters3 list
+ * @gh: the holder
+ *
+ * If there is only one other recursive holder, clear its HIF_RECURSE bit.
+ * If there is more than one, leave them alone.
+ *
+ */
+
+static void do_unrecurse(struct gfs2_holder *gh)
+{
+	struct gfs2_glock *gl = gh->gh_gl;
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct gfs2_holder *tmp_gh, *last_gh = NULL;
+	int found = 0;
+
+	if (gfs2_assert_warn(sdp, gh->gh_owner))
+		return;
+
+	list_for_each_entry(tmp_gh, &gl->gl_waiters3, gh_list) {
+		if (tmp_gh->gh_owner != gh->gh_owner)
+			continue;
+
+		gfs2_assert_warn(sdp,
+				 test_bit(HIF_RECURSE, &tmp_gh->gh_iflags));
+
+		if (found)
+			return;
+
+		found = 1;
+		last_gh = tmp_gh;
+	}
+
+	if (!gfs2_assert_warn(sdp, found))
+		clear_bit(HIF_RECURSE, &last_gh->gh_iflags);
+}
+
+/**
+ * rq_mutex - process a mutex request in the queue
+ * @gh: the glock holder
+ *
+ * Returns: 1 if the queue is blocked
+ */
+
+static int rq_mutex(struct gfs2_holder *gh)
+{
+	struct gfs2_glock *gl = gh->gh_gl;
+
+	list_del_init(&gh->gh_list);
+	/*  gh->gh_error never examined.  */
+	set_bit(GLF_LOCK, &gl->gl_flags);
+	complete(&gh->gh_wait);
+
+	return 1;
+}
+
+/**
+ * rq_promote - process a promote request in the queue
+ * @gh: the glock holder
+ *
+ * Acquire a new inter-node lock, or change a lock state to more restrictive.
+ *
+ * Returns: 1 if the queue is blocked
+ */
+
+static int rq_promote(struct gfs2_holder *gh)
+{
+	struct gfs2_glock *gl = gh->gh_gl;
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct gfs2_glock_operations *glops = gl->gl_ops;
+	int recurse;
+
+	if (!relaxed_state_ok(gl->gl_state, gh->gh_state, gh->gh_flags)) {
+		if (list_empty(&gl->gl_holders)) {
+			gl->gl_req_gh = gh;
+			set_bit(GLF_LOCK, &gl->gl_flags);
+			spin_unlock(&gl->gl_spin);
+
+			if (atomic_read(&sdp->sd_reclaim_count) >
+			    gfs2_tune_get(sdp, gt_reclaim_limit) &&
+			    !(gh->gh_flags & LM_FLAG_PRIORITY)) {
+				gfs2_reclaim_glock(sdp);
+				gfs2_reclaim_glock(sdp);
+			}
+
+			glops->go_xmote_th(gl, gh->gh_state,
+					   gh->gh_flags);
+
+			spin_lock(&gl->gl_spin);
+		}
+		return 1;
+	}
+
+	if (list_empty(&gl->gl_holders)) {
+		set_bit(HIF_FIRST, &gh->gh_iflags);
+		set_bit(GLF_LOCK, &gl->gl_flags);
+		recurse = 0;
+	} else {
+		struct gfs2_holder *next_gh;
+		if (gh->gh_flags & GL_LOCAL_EXCL)
+			return 1;
+		next_gh = list_entry(gl->gl_holders.next, struct gfs2_holder,
+				     gh_list);
+		if (next_gh->gh_flags & GL_LOCAL_EXCL)
+			 return 1;
+		recurse = test_bit(HIF_RECURSE, &gh->gh_iflags);
+	}
+
+	list_move_tail(&gh->gh_list, &gl->gl_holders);
+	gh->gh_error = 0;
+	set_bit(HIF_HOLDER, &gh->gh_iflags);
+
+	if (recurse)
+		handle_recurse(gh);
+
+	complete(&gh->gh_wait);
+
+	return 0;
+}
+
+/**
+ * rq_demote - process a demote request in the queue
+ * @gh: the glock holder
+ *
+ * Returns: 1 if the queue is blocked
+ */
+
+static int rq_demote(struct gfs2_holder *gh)
+{
+	struct gfs2_glock *gl = gh->gh_gl;
+	struct gfs2_glock_operations *glops = gl->gl_ops;
+
+	if (!list_empty(&gl->gl_holders))
+		return 1;
+
+	if (gl->gl_state == gh->gh_state || gl->gl_state == LM_ST_UNLOCKED) {
+		list_del_init(&gh->gh_list);
+		gh->gh_error = 0;
+		spin_unlock(&gl->gl_spin);
+		if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
+			gfs2_holder_put(gh);
+		else
+			complete(&gh->gh_wait);
+		spin_lock(&gl->gl_spin);
+	} else {
+		gl->gl_req_gh = gh;
+		set_bit(GLF_LOCK, &gl->gl_flags);
+		spin_unlock(&gl->gl_spin);
+
+		if (gh->gh_state == LM_ST_UNLOCKED ||
+		    gl->gl_state != LM_ST_EXCLUSIVE)
+			glops->go_drop_th(gl);
+		else
+			glops->go_xmote_th(gl, gh->gh_state, gh->gh_flags);
+
+		spin_lock(&gl->gl_spin);
+	}
+
+	return 0;
+}
+
+/**
+ * rq_greedy - process a queued request to drop greedy status
+ * @gh: the glock holder
+ *
+ * Returns: 1 if the queue is blocked
+ */
+
+static int rq_greedy(struct gfs2_holder *gh)
+{
+	struct gfs2_glock *gl = gh->gh_gl;
+
+	list_del_init(&gh->gh_list);
+	/*  gh->gh_error never examined.  */
+	clear_bit(GLF_GREEDY, &gl->gl_flags);
+	spin_unlock(&gl->gl_spin);
+
+	gfs2_holder_uninit(gh);
+	kfree(container_of(gh, struct greedy, gr_gh));
+
+	spin_lock(&gl->gl_spin);		
+
+	return 0;
+}
+
+/**
+ * run_queue - process holder structures on a glock
+ * @gl: the glock
+ *
+ */
+
+static void run_queue(struct gfs2_glock *gl)
+{
+	struct gfs2_holder *gh;
+	int blocked = 1;
+
+	for (;;) {
+		if (test_bit(GLF_LOCK, &gl->gl_flags))
+			break;
+
+		if (!list_empty(&gl->gl_waiters1)) {
+			gh = list_entry(gl->gl_waiters1.next,
+					struct gfs2_holder, gh_list);
+
+			if (test_bit(HIF_MUTEX, &gh->gh_iflags))
+				blocked = rq_mutex(gh);
+			else
+				gfs2_assert_warn(gl->gl_sbd, 0);
+
+		} else if (!list_empty(&gl->gl_waiters2) &&
+			   !test_bit(GLF_SKIP_WAITERS2, &gl->gl_flags)) {
+			gh = list_entry(gl->gl_waiters2.next,
+					struct gfs2_holder, gh_list);
+
+			if (test_bit(HIF_DEMOTE, &gh->gh_iflags))
+				blocked = rq_demote(gh);
+			else if (test_bit(HIF_GREEDY, &gh->gh_iflags))
+				blocked = rq_greedy(gh);
+			else
+				gfs2_assert_warn(gl->gl_sbd, 0);
+
+		} else if (!list_empty(&gl->gl_waiters3)) {
+			gh = list_entry(gl->gl_waiters3.next,
+					struct gfs2_holder, gh_list);
+
+			if (test_bit(HIF_PROMOTE, &gh->gh_iflags))
+				blocked = rq_promote(gh);
+			else
+				gfs2_assert_warn(gl->gl_sbd, 0);
+
+		} else
+			break;
+
+		if (blocked)
+			break;
+	}
+}
+
+/**
+ * gfs2_glmutex_lock - acquire a local lock on a glock
+ * @gl: the glock
+ *
+ * Gives caller exclusive access to manipulate a glock structure.
+ */
+
+void gfs2_glmutex_lock(struct gfs2_glock *gl)
+{
+	struct gfs2_holder gh;
+
+	gfs2_holder_init(gl, 0, 0, &gh);
+	set_bit(HIF_MUTEX, &gh.gh_iflags);
+
+	spin_lock(&gl->gl_spin);
+	if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
+		list_add_tail(&gh.gh_list, &gl->gl_waiters1);
+	else
+		complete(&gh.gh_wait);
+	spin_unlock(&gl->gl_spin);
+
+	wait_for_completion(&gh.gh_wait);
+	gfs2_holder_uninit(&gh);
+}
+
+/**
+ * gfs2_glmutex_trylock - try to acquire a local lock on a glock
+ * @gl: the glock
+ *
+ * Returns: 1 if the glock is acquired
+ */
+
+int gfs2_glmutex_trylock(struct gfs2_glock *gl)
+{
+	int acquired = 1;
+
+	spin_lock(&gl->gl_spin);
+	if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
+		acquired = 0;
+	spin_unlock(&gl->gl_spin);
+
+	return acquired;
+}
+
+/**
+ * gfs2_glmutex_unlock - release a local lock on a glock
+ * @gl: the glock
+ *
+ */
+
+void gfs2_glmutex_unlock(struct gfs2_glock *gl)
+{
+	spin_lock(&gl->gl_spin);
+	clear_bit(GLF_LOCK, &gl->gl_flags);
+	run_queue(gl);
+	spin_unlock(&gl->gl_spin);
+}
+
+/**
+ * handle_callback - add a demote request to a lock's queue
+ * @gl: the glock
+ * @state: the state the caller wants us to change to
+ *
+ */
+
+static void handle_callback(struct gfs2_glock *gl, unsigned int state)
+{
+	struct gfs2_holder *gh, *new_gh = NULL;
+
+ restart:
+	spin_lock(&gl->gl_spin);
+
+	list_for_each_entry(gh, &gl->gl_waiters2, gh_list) {
+		if (test_bit(HIF_DEMOTE, &gh->gh_iflags) &&
+		    gl->gl_req_gh != gh) {
+			if (gh->gh_state != state)
+				gh->gh_state = LM_ST_UNLOCKED;
+			goto out;
+		}
+	}
+
+	if (new_gh) {
+		list_add_tail(&new_gh->gh_list, &gl->gl_waiters2);
+		new_gh = NULL;
+	} else {
+		spin_unlock(&gl->gl_spin);
+
+		new_gh = gfs2_holder_get(gl, state,
+					 LM_FLAG_TRY | GL_NEVER_RECURSE,
+					 GFP_KERNEL | __GFP_NOFAIL),
+		set_bit(HIF_DEMOTE, &new_gh->gh_iflags);
+		set_bit(HIF_DEALLOC, &new_gh->gh_iflags);
+
+		goto restart;
+	}
+
+ out:
+	spin_unlock(&gl->gl_spin);
+
+	if (new_gh)
+		gfs2_holder_put(new_gh);
+}
+
+/**
+ * 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)
+{
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	int held1, held2;
+
+	held1 = (gl->gl_state != LM_ST_UNLOCKED);
+	held2 = (new_state != LM_ST_UNLOCKED);
+
+	if (held1 != held2) {
+		if (held2) {
+			atomic_inc(&sdp->sd_glock_held_count);
+			gfs2_glock_hold(gl);
+		} else {
+			atomic_dec(&sdp->sd_glock_held_count);
+			gfs2_glock_put(gl);
+		}
+	}
+
+	gl->gl_state = new_state;
+}
+
+/**
+ * xmote_bh - Called after the lock module is done acquiring a lock
+ * @gl: The glock in question
+ * @ret: the int returned from the lock module
+ *
+ */
+
+static void xmote_bh(struct gfs2_glock *gl, unsigned int ret)
+{
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct gfs2_glock_operations *glops = gl->gl_ops;
+	struct gfs2_holder *gh = gl->gl_req_gh;
+	int prev_state = gl->gl_state;
+	int op_done = 1;
+
+	gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
+	gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
+	gfs2_assert_warn(sdp, !(ret & LM_OUT_ASYNC));
+
+	state_change(gl, ret & LM_OUT_ST_MASK);
+
+	if (prev_state != LM_ST_UNLOCKED && !(ret & LM_OUT_CACHEABLE)) {
+		if (glops->go_inval)
+			glops->go_inval(gl, DIO_METADATA | DIO_DATA);
+	} else if (gl->gl_state == LM_ST_DEFERRED) {
+		/* We might not want to do this here.
+		   Look at moving to the inode glops. */
+		if (glops->go_inval)
+			glops->go_inval(gl, DIO_DATA);
+	}
+
+	/*  Deal with each possible exit condition  */
+
+	if (!gh)
+		gl->gl_stamp = jiffies;
+
+	else if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
+		spin_lock(&gl->gl_spin);
+		list_del_init(&gh->gh_list);
+		gh->gh_error = -EIO;
+		if (test_bit(HIF_RECURSE, &gh->gh_iflags))
+			do_unrecurse(gh);
+		spin_unlock(&gl->gl_spin);
+
+	} else if (test_bit(HIF_DEMOTE, &gh->gh_iflags)) {
+		spin_lock(&gl->gl_spin);
+		list_del_init(&gh->gh_list);
+		if (gl->gl_state == gh->gh_state ||
+		    gl->gl_state == LM_ST_UNLOCKED)
+			gh->gh_error = 0;
+		else {
+			if (gfs2_assert_warn(sdp, gh->gh_flags &
+					(LM_FLAG_TRY | LM_FLAG_TRY_1CB)) == -1)
+				fs_warn(sdp, "ret = 0x%.8X\n", ret);
+			gh->gh_error = GLR_TRYFAILED;
+		}
+		spin_unlock(&gl->gl_spin);
+
+		if (ret & LM_OUT_CANCELED)
+			handle_callback(gl, LM_ST_UNLOCKED); /* Lame */
+
+	} else if (ret & LM_OUT_CANCELED) {
+		spin_lock(&gl->gl_spin);
+		list_del_init(&gh->gh_list);
+		gh->gh_error = GLR_CANCELED;
+		if (test_bit(HIF_RECURSE, &gh->gh_iflags))
+			do_unrecurse(gh);
+		spin_unlock(&gl->gl_spin);
+
+	} else if (relaxed_state_ok(gl->gl_state, gh->gh_state, gh->gh_flags)) {
+		spin_lock(&gl->gl_spin);
+		list_move_tail(&gh->gh_list, &gl->gl_holders);
+		gh->gh_error = 0;
+		set_bit(HIF_HOLDER, &gh->gh_iflags);
+		spin_unlock(&gl->gl_spin);
+
+		set_bit(HIF_FIRST, &gh->gh_iflags);
+
+		op_done = 0;
+
+	} else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
+		spin_lock(&gl->gl_spin);
+		list_del_init(&gh->gh_list);
+		gh->gh_error = GLR_TRYFAILED;
+		if (test_bit(HIF_RECURSE, &gh->gh_iflags))
+			do_unrecurse(gh);
+		spin_unlock(&gl->gl_spin);
+
+	} else {
+		if (gfs2_assert_withdraw(sdp, 0) == -1)
+			fs_err(sdp, "ret = 0x%.8X\n", ret);
+	}
+
+	if (glops->go_xmote_bh)
+		glops->go_xmote_bh(gl);
+
+	if (op_done) {
+		spin_lock(&gl->gl_spin);
+		gl->gl_req_gh = NULL;
+		gl->gl_req_bh = NULL;
+		clear_bit(GLF_LOCK, &gl->gl_flags);
+		run_queue(gl);
+		spin_unlock(&gl->gl_spin);
+	}
+
+	gfs2_glock_put(gl);
+
+	if (gh) {
+		if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
+			gfs2_holder_put(gh);
+		else
+			complete(&gh->gh_wait);
+	}
+}
+
+/**
+ * gfs2_glock_xmote_th - Call into the lock module to acquire or change a glock
+ * @gl: The glock in question
+ * @state: the requested state
+ * @flags: modifier flags to the lock call
+ *
+ */
+
+void gfs2_glock_xmote_th(struct gfs2_glock *gl, unsigned int state, int flags)
+{
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct gfs2_glock_operations *glops = gl->gl_ops;
+	int lck_flags = flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB |
+				 LM_FLAG_NOEXP | LM_FLAG_ANY |
+				 LM_FLAG_PRIORITY);
+	unsigned int lck_ret;
+
+	gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
+	gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
+	gfs2_assert_warn(sdp, state != LM_ST_UNLOCKED);
+	gfs2_assert_warn(sdp, state != gl->gl_state);
+
+	if (gl->gl_state == LM_ST_EXCLUSIVE) {
+		if (glops->go_sync)
+			glops->go_sync(gl,
+				       DIO_METADATA | DIO_DATA | DIO_RELEASE);
+	}
+
+	gfs2_glock_hold(gl);
+	gl->gl_req_bh = xmote_bh;
+
+	atomic_inc(&sdp->sd_lm_lock_calls);
+
+	lck_ret = gfs2_lm_lock(sdp, gl->gl_lock, gl->gl_state, state,
+			       lck_flags);
+
+	if (gfs2_assert_withdraw(sdp, !(lck_ret & LM_OUT_ERROR)))
+		return;
+
+	if (lck_ret & LM_OUT_ASYNC)
+		gfs2_assert_warn(sdp, lck_ret == LM_OUT_ASYNC);
+	else
+		xmote_bh(gl, lck_ret);
+}
+
+/**
+ * drop_bh - Called after a lock module unlock completes
+ * @gl: the glock
+ * @ret: the return status
+ *
+ * Doesn't wake up the process waiting on the struct gfs2_holder (if any)
+ * Doesn't drop the reference on the glock the top half took out
+ *
+ */
+
+static void drop_bh(struct gfs2_glock *gl, unsigned int ret)
+{
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct gfs2_glock_operations *glops = gl->gl_ops;
+	struct gfs2_holder *gh = gl->gl_req_gh;
+
+	clear_bit(GLF_PREFETCH, &gl->gl_flags);
+
+	gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
+	gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
+	gfs2_assert_warn(sdp, !ret);
+
+	state_change(gl, LM_ST_UNLOCKED);
+
+	if (glops->go_inval)
+		glops->go_inval(gl, DIO_METADATA | DIO_DATA);
+
+	if (gh) {
+		spin_lock(&gl->gl_spin);
+		list_del_init(&gh->gh_list);
+		gh->gh_error = 0;
+		spin_unlock(&gl->gl_spin);
+	}
+
+	if (glops->go_drop_bh)
+		glops->go_drop_bh(gl);
+
+	spin_lock(&gl->gl_spin);
+	gl->gl_req_gh = NULL;
+	gl->gl_req_bh = NULL;
+	clear_bit(GLF_LOCK, &gl->gl_flags);
+	run_queue(gl);
+	spin_unlock(&gl->gl_spin);
+
+	gfs2_glock_put(gl);
+
+	if (gh) {
+		if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
+			gfs2_holder_put(gh);
+		else
+			complete(&gh->gh_wait);
+	}
+}
+
+/**
+ * gfs2_glock_drop_th - call into the lock module to unlock a lock
+ * @gl: the glock
+ *
+ */
+
+void gfs2_glock_drop_th(struct gfs2_glock *gl)
+{
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct gfs2_glock_operations *glops = gl->gl_ops;
+	unsigned int ret;
+
+	gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
+	gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
+	gfs2_assert_warn(sdp, gl->gl_state != LM_ST_UNLOCKED);
+
+	if (gl->gl_state == LM_ST_EXCLUSIVE) {
+		if (glops->go_sync)
+			glops->go_sync(gl,
+				       DIO_METADATA | DIO_DATA | DIO_RELEASE);
+	}
+
+	gfs2_glock_hold(gl);
+	gl->gl_req_bh = drop_bh;
+
+	atomic_inc(&sdp->sd_lm_unlock_calls);
+
+	ret = gfs2_lm_unlock(sdp, gl->gl_lock, gl->gl_state);
+
+	if (gfs2_assert_withdraw(sdp, !(ret & LM_OUT_ERROR)))
+		return;
+
+	if (!ret)
+		drop_bh(gl, ret);
+	else
+		gfs2_assert_warn(sdp, ret == LM_OUT_ASYNC);
+}
+
+/**
+ * do_cancels - cancel requests for locks stuck waiting on an expire flag
+ * @gh: the LM_FLAG_PRIORITY holder waiting to acquire the lock
+ *
+ * Don't cancel GL_NOCANCEL requests.
+ */
+
+static void do_cancels(struct gfs2_holder *gh)
+{
+	struct gfs2_glock *gl = gh->gh_gl;
+
+	spin_lock(&gl->gl_spin);
+
+	while (gl->gl_req_gh != gh &&
+	       !test_bit(HIF_HOLDER, &gh->gh_iflags) &&
+	       !list_empty(&gh->gh_list)) {
+		if (gl->gl_req_bh &&
+		    !(gl->gl_req_gh &&
+		      (gl->gl_req_gh->gh_flags & GL_NOCANCEL))) {
+			spin_unlock(&gl->gl_spin);
+			gfs2_lm_cancel(gl->gl_sbd, gl->gl_lock);
+			msleep(100);
+			spin_lock(&gl->gl_spin);
+		} else {
+			spin_unlock(&gl->gl_spin);
+			msleep(100);
+			spin_lock(&gl->gl_spin);
+		}
+	}
+
+	spin_unlock(&gl->gl_spin);
+}
+
+/**
+ * glock_wait_internal - wait on a glock acquisition
+ * @gh: the glock holder
+ *
+ * Returns: 0 on success
+ */
+
+static int glock_wait_internal(struct gfs2_holder *gh)
+{
+	struct gfs2_glock *gl = gh->gh_gl;
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct gfs2_glock_operations *glops = gl->gl_ops;
+	int error = 0;
+
+	if (test_bit(HIF_ABORTED, &gh->gh_iflags))
+		return -EIO;
+
+	if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
+		spin_lock(&gl->gl_spin);
+		if (gl->gl_req_gh != gh &&
+		    !test_bit(HIF_HOLDER, &gh->gh_iflags) &&
+		    !list_empty(&gh->gh_list)) {
+			list_del_init(&gh->gh_list);
+			gh->gh_error = GLR_TRYFAILED;
+			if (test_bit(HIF_RECURSE, &gh->gh_iflags))
+				do_unrecurse(gh);
+			run_queue(gl);
+			spin_unlock(&gl->gl_spin);
+			return GLR_TRYFAILED;
+		}
+		spin_unlock(&gl->gl_spin);
+	}
+
+	if (gh->gh_flags & LM_FLAG_PRIORITY)
+		do_cancels(gh);
+
+	wait_for_completion(&gh->gh_wait);
+
+	if (gh->gh_error)
+		return gh->gh_error;
+
+	gfs2_assert_withdraw(sdp, test_bit(HIF_HOLDER, &gh->gh_iflags));
+	gfs2_assert_withdraw(sdp, relaxed_state_ok(gl->gl_state,
+						   gh->gh_state,
+						   gh->gh_flags));
+
+	if (test_bit(HIF_FIRST, &gh->gh_iflags)) {
+		gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
+
+		if (glops->go_lock) {
+			error = glops->go_lock(gh);
+			if (error) {
+				spin_lock(&gl->gl_spin);
+				list_del_init(&gh->gh_list);
+				gh->gh_error = error;
+				if (test_and_clear_bit(HIF_RECURSE,
+						       &gh->gh_iflags))
+					do_unrecurse(gh);
+				spin_unlock(&gl->gl_spin);
+			}
+		}
+
+		spin_lock(&gl->gl_spin);
+		gl->gl_req_gh = NULL;
+		gl->gl_req_bh = NULL;
+		clear_bit(GLF_LOCK, &gl->gl_flags);
+		if (test_bit(HIF_RECURSE, &gh->gh_iflags))
+			handle_recurse(gh);
+		run_queue(gl);
+		spin_unlock(&gl->gl_spin);
+	}
+
+	return error;
+}
+
+static inline struct gfs2_holder *
+find_holder_by_owner(struct list_head *head, struct task_struct *owner)
+{
+	struct gfs2_holder *gh;
+
+	list_for_each_entry(gh, head, gh_list) {
+		if (gh->gh_owner == owner)
+			return gh;
+	}
+
+	return NULL;
+}
+
+/**
+ * recurse_check -
+ *
+ * Make sure the new holder is compatible with the pre-existing one.
+ *
+ */
+
+static int recurse_check(struct gfs2_holder *existing, struct gfs2_holder *new,
+			 unsigned int state)
+{
+	struct gfs2_sbd *sdp = existing->gh_gl->gl_sbd;
+
+	if (gfs2_assert_warn(sdp, (new->gh_flags & LM_FLAG_ANY) ||
+			          !(existing->gh_flags & LM_FLAG_ANY)))
+		goto fail;
+
+	if (gfs2_assert_warn(sdp, (existing->gh_flags & GL_LOCAL_EXCL) ||
+				  !(new->gh_flags & GL_LOCAL_EXCL)))
+		goto fail;
+
+	if (gfs2_assert_warn(sdp, relaxed_state_ok(state, new->gh_state,
+						   new->gh_flags)))
+		goto fail;
+
+	return 0;
+
+ fail:
+	set_bit(HIF_ABORTED, &new->gh_iflags);
+	return -EINVAL;
+}
+
+/**
+ * add_to_queue - Add a holder to the wait queue (but look for recursion)
+ * @gh: the holder structure to add
+ *
+ */
+
+static void add_to_queue(struct gfs2_holder *gh)
+{
+	struct gfs2_glock *gl = gh->gh_gl;
+	struct gfs2_holder *existing;
+
+	if (!gh->gh_owner)
+		goto out;
+
+	existing = find_holder_by_owner(&gl->gl_holders, gh->gh_owner);
+	if (existing) {
+		if (recurse_check(existing, gh, gl->gl_state))
+			return;
+
+		list_add_tail(&gh->gh_list, &gl->gl_holders);
+		set_bit(HIF_HOLDER, &gh->gh_iflags);
+
+		gh->gh_error = 0;
+		complete(&gh->gh_wait);
+
+		return;
+	}
+
+	existing = find_holder_by_owner(&gl->gl_waiters3, gh->gh_owner);
+	if (existing) {
+		if (recurse_check(existing, gh, existing->gh_state))
+			return;
+
+		set_bit(HIF_RECURSE, &gh->gh_iflags);
+		set_bit(HIF_RECURSE, &existing->gh_iflags);
+
+		list_add_tail(&gh->gh_list, &gl->gl_waiters3);
+
+		return;
+	}
+
+ out:
+	if (gh->gh_flags & LM_FLAG_PRIORITY)
+		list_add(&gh->gh_list, &gl->gl_waiters3);
+	else
+		list_add_tail(&gh->gh_list, &gl->gl_waiters3);	
+}
+
+/**
+ * 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;
+
+	atomic_inc(&sdp->sd_glock_nq_calls);
+
+ restart:
+	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
+		set_bit(HIF_ABORTED, &gh->gh_iflags);
+		return -EIO;
+	}
+
+	set_bit(HIF_PROMOTE, &gh->gh_iflags);
+
+	spin_lock(&gl->gl_spin);
+	add_to_queue(gh);
+	run_queue(gl);
+	spin_unlock(&gl->gl_spin);
+
+	if (!(gh->gh_flags & GL_ASYNC)) {
+		error = glock_wait_internal(gh);
+		if (error == GLR_CANCELED) {
+			msleep(1000);
+			goto restart;
+		}
+	}
+
+	clear_bit(GLF_PREFETCH, &gl->gl_flags);
+
+	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)
+{
+	struct gfs2_glock *gl = gh->gh_gl;
+	int ready = 0;
+
+	spin_lock(&gl->gl_spin);
+
+	if (test_bit(HIF_HOLDER, &gh->gh_iflags))
+		ready = 1;
+	else if (list_empty(&gh->gh_list)) {
+		if (gh->gh_error == GLR_CANCELED) {
+			spin_unlock(&gl->gl_spin);
+			msleep(1000);
+			if (gfs2_glock_nq(gh))
+				return 1;
+			return 0;
+		} else
+			ready = 1;
+	}
+
+	spin_unlock(&gl->gl_spin);
+
+	return ready;
+}
+
+/**
+ * gfs2_glock_wait - wait for a lock acquisition that ended in a GLR_ASYNC
+ * @gh: the holder structure
+ *
+ * Returns: 0, GLR_TRYFAILED, or errno on failure
+ */
+
+int gfs2_glock_wait(struct gfs2_holder *gh)
+{
+	int error;
+
+	error = glock_wait_internal(gh);
+	if (error == GLR_CANCELED) {
+		msleep(1000);
+		gh->gh_flags &= ~GL_ASYNC;
+		error = gfs2_glock_nq(gh);
+	}
+
+	return error;
+}
+
+/**
+ * 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;
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct gfs2_glock_operations *glops = gl->gl_ops;
+
+	atomic_inc(&sdp->sd_glock_dq_calls);
+
+	if (gh->gh_flags & GL_SYNC)
+		set_bit(GLF_SYNC, &gl->gl_flags);
+
+	if (gh->gh_flags & GL_NOCACHE)
+		handle_callback(gl, LM_ST_UNLOCKED);
+
+	gfs2_glmutex_lock(gl);
+
+	spin_lock(&gl->gl_spin);
+	list_del_init(&gh->gh_list);
+
+	if (list_empty(&gl->gl_holders)) {
+		spin_unlock(&gl->gl_spin);
+
+		if (glops->go_unlock)
+			glops->go_unlock(gh);
+
+		if (test_bit(GLF_SYNC, &gl->gl_flags)) {
+			if (glops->go_sync)
+				glops->go_sync(gl, DIO_METADATA | DIO_DATA);
+		}
+
+		gl->gl_stamp = jiffies;
+
+		spin_lock(&gl->gl_spin);
+	}
+
+	clear_bit(GLF_LOCK, &gl->gl_flags);
+	run_queue(gl);
+	spin_unlock(&gl->gl_spin);
+}
+
+/**
+ * gfs2_glock_prefetch - Try to prefetch a glock
+ * @gl: the glock
+ * @state: the state to prefetch in
+ * @flags: flags passed to go_xmote_th()
+ *
+ */
+
+void gfs2_glock_prefetch(struct gfs2_glock *gl, unsigned int state, int flags)
+{
+	struct gfs2_glock_operations *glops = gl->gl_ops;
+
+	spin_lock(&gl->gl_spin);
+
+	if (test_bit(GLF_LOCK, &gl->gl_flags) ||
+	    !list_empty(&gl->gl_holders) ||
+	    !list_empty(&gl->gl_waiters1) ||
+	    !list_empty(&gl->gl_waiters2) ||
+	    !list_empty(&gl->gl_waiters3) ||
+	    relaxed_state_ok(gl->gl_state, state, flags)) {
+		spin_unlock(&gl->gl_spin);
+		return;
+	}
+
+	set_bit(GLF_PREFETCH, &gl->gl_flags);
+	set_bit(GLF_LOCK, &gl->gl_flags);
+	spin_unlock(&gl->gl_spin);
+
+	glops->go_xmote_th(gl, state, flags);
+
+	atomic_inc(&gl->gl_sbd->sd_glock_prefetch_calls);
+}
+
+/**
+ * gfs2_glock_force_drop - Force a glock to be uncached
+ * @gl: the glock
+ *
+ */
+
+void gfs2_glock_force_drop(struct gfs2_glock *gl)
+{
+	struct gfs2_holder gh;
+
+	gfs2_holder_init(gl, LM_ST_UNLOCKED, GL_NEVER_RECURSE, &gh);
+	set_bit(HIF_DEMOTE, &gh.gh_iflags);
+
+	spin_lock(&gl->gl_spin);
+	list_add_tail(&gh.gh_list, &gl->gl_waiters2);
+	run_queue(gl);
+	spin_unlock(&gl->gl_spin);
+
+	wait_for_completion(&gh.gh_wait);
+	gfs2_holder_uninit(&gh);
+}
+
+static void greedy_work(void *data)
+{
+	struct greedy *gr = (struct greedy *)data;
+	struct gfs2_holder *gh = &gr->gr_gh;
+	struct gfs2_glock *gl = gh->gh_gl;
+	struct gfs2_glock_operations *glops = gl->gl_ops;
+
+	clear_bit(GLF_SKIP_WAITERS2, &gl->gl_flags);
+
+	if (glops->go_greedy)
+		glops->go_greedy(gl);
+
+	spin_lock(&gl->gl_spin);
+
+	if (list_empty(&gl->gl_waiters2)) {
+		clear_bit(GLF_GREEDY, &gl->gl_flags);
+		spin_unlock(&gl->gl_spin);
+		gfs2_holder_uninit(gh);
+		kfree(gr);
+	} else {
+		gfs2_glock_hold(gl);
+		list_add_tail(&gh->gh_list, &gl->gl_waiters2);
+		run_queue(gl);
+		spin_unlock(&gl->gl_spin);
+		gfs2_glock_put(gl);
+	}
+}
+
+/**
+ * gfs2_glock_be_greedy -
+ * @gl:
+ * @time:
+ *
+ * Returns: 0 if go_greedy will be called, 1 otherwise
+ */
+
+int gfs2_glock_be_greedy(struct gfs2_glock *gl, unsigned int time)
+{
+	struct greedy *gr;
+	struct gfs2_holder *gh;
+
+	if (!time ||
+	    gl->gl_sbd->sd_args.ar_localcaching ||
+	    test_and_set_bit(GLF_GREEDY, &gl->gl_flags))
+		return 1;
+
+	gr = kmalloc(sizeof(struct greedy), GFP_KERNEL);
+	if (!gr) {
+		clear_bit(GLF_GREEDY, &gl->gl_flags);
+		return 1;
+	}
+	gh = &gr->gr_gh;
+
+	gfs2_holder_init(gl, 0, GL_NEVER_RECURSE, gh);
+	set_bit(HIF_GREEDY, &gh->gh_iflags);
+	INIT_WORK(&gr->gr_work, greedy_work, gr);
+
+	set_bit(GLF_SKIP_WAITERS2, &gl->gl_flags);
+	schedule_delayed_work(&gr->gr_work, time);
+
+	return 0;
+}
+
+/**
+ * gfs2_glock_nq_init - intialize a holder and enqueue it on a glock
+ * @gl: the glock
+ * @state: the state we're requesting
+ * @flags: the modifier flags
+ * @gh: the holder structure
+ *
+ * Returns: 0, GLR_*, or errno
+ */
+
+int gfs2_glock_nq_init(struct gfs2_glock *gl, unsigned int state, int flags,
+		       struct gfs2_holder *gh)
+{
+	int error;
+
+	gfs2_holder_init(gl, state, flags, gh);
+
+	error = gfs2_glock_nq(gh);
+	if (error)
+		gfs2_holder_uninit(gh);
+
+	return error;
+}
+
+/**
+ * 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 aquisition
+ * @gh: the struct gfs2_holder
+ *
+ * Returns: errno
+ */
+
+int gfs2_glock_nq_num(struct gfs2_sbd *sdp, uint64_t number,
+		      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)
+{
+	struct gfs2_holder *gh_a = *(struct gfs2_holder **)arg_a;
+	struct gfs2_holder *gh_b = *(struct gfs2_holder **)arg_b;
+	struct lm_lockname *a = &gh_a->gh_gl->gl_name;
+	struct lm_lockname *b = &gh_b->gh_gl->gl_name;
+	int ret = 0;
+
+	if (a->ln_number > b->ln_number)
+		ret = 1;
+	else if (a->ln_number < b->ln_number)
+		ret = -1;
+	else {
+		if (gh_a->gh_state == LM_ST_SHARED &&
+		    gh_b->gh_state == LM_ST_EXCLUSIVE)
+			ret = 1;
+		else if (!(gh_a->gh_flags & GL_LOCAL_EXCL) &&
+			 (gh_b->gh_flags & GL_LOCAL_EXCL))
+			ret = 1;
+	}
+
+	return ret;
+}
+
+/**
+ * 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
+ *
+ * Figure out how big an impact this function has.  Either:
+ * 1) Replace this code with code that calls gfs2_glock_prefetch()
+ * 2) Forget async stuff and just call nq_m_sync()
+ * 3) Leave it like it is
+ *
+ * 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)
+{
+	int *e;
+	unsigned int x;
+	int borked = 0, serious = 0;
+	int error = 0;
+
+	if (!num_gh)
+		return 0;
+
+	if (num_gh == 1) {
+		ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
+		return gfs2_glock_nq(ghs);
+	}
+
+	e = kcalloc(num_gh, sizeof(struct gfs2_holder *), GFP_KERNEL);
+	if (!e)
+		return -ENOMEM;
+
+	for (x = 0; x < num_gh; x++) {
+		ghs[x].gh_flags |= LM_FLAG_TRY | GL_ASYNC;
+		error = gfs2_glock_nq(&ghs[x]);
+		if (error) {
+			borked = 1;
+			serious = error;
+			num_gh = x;
+			break;
+		}
+	}
+
+	for (x = 0; x < num_gh; x++) {
+		error = e[x] = glock_wait_internal(&ghs[x]);
+		if (error) {
+			borked = 1;
+			if (error != GLR_TRYFAILED && error != GLR_CANCELED)
+				serious = error;
+		}
+	}
+
+	if (!borked) {
+		kfree(e);
+		return 0;
+	}
+
+	for (x = 0; x < num_gh; x++)
+		if (!e[x])
+			gfs2_glock_dq(&ghs[x]);
+
+	if (serious)
+		error = serious;
+	else {
+		for (x = 0; x < num_gh; x++)
+			gfs2_holder_reinit(ghs[x].gh_state, ghs[x].gh_flags,
+					  &ghs[x]);
+		error = nq_m_sync(num_gh, ghs, (struct gfs2_holder **)e);
+	}
+
+	kfree(e);
+
+	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)
+{
+	unsigned int x;
+
+	for (x = 0; x < num_gh; x++)
+		gfs2_glock_dq(&ghs[x]);
+}
+
+/**
+ * gfs2_glock_dq_uninit_m - release multiple glocks
+ * @num_gh: the number of structures
+ * @ghs: an array of struct gfs2_holder structures
+ *
+ */
+
+void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
+{
+	unsigned int x;
+
+	for (x = 0; x < num_gh; x++)
+		gfs2_glock_dq_uninit(&ghs[x]);
+}
+
+/**
+ * gfs2_glock_prefetch_num - prefetch 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 aquisition
+ *
+ * Returns: errno
+ */
+
+void gfs2_glock_prefetch_num(struct gfs2_sbd *sdp, uint64_t number,
+			     struct gfs2_glock_operations *glops,
+			     unsigned int state, int flags)
+{
+	struct gfs2_glock *gl;
+	int error;
+
+	if (atomic_read(&sdp->sd_reclaim_count) <
+	    gfs2_tune_get(sdp, gt_reclaim_limit)) {
+		error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
+		if (!error) {
+			gfs2_glock_prefetch(gl, state, flags);
+			gfs2_glock_put(gl);
+		}
+	}
+}
+
+/**
+ * gfs2_lvb_hold - attach a LVB from a glock
+ * @gl: The glock in question
+ *
+ */
+
+int gfs2_lvb_hold(struct gfs2_glock *gl)
+{
+	int error;
+
+	gfs2_glmutex_lock(gl);
+
+	if (!atomic_read(&gl->gl_lvb_count)) {
+		error = gfs2_lm_hold_lvb(gl->gl_sbd, gl->gl_lock, &gl->gl_lvb);
+		if (error) {
+			gfs2_glmutex_unlock(gl);
+			return error;
+		}
+		gfs2_glock_hold(gl);
+	}
+	atomic_inc(&gl->gl_lvb_count);
+
+	gfs2_glmutex_unlock(gl);
+
+	return 0;
+}
+
+/**
+ * gfs2_lvb_unhold - detach a LVB from a glock
+ * @gl: The glock in question
+ *
+ */
+
+void gfs2_lvb_unhold(struct gfs2_glock *gl)
+{
+	gfs2_glock_hold(gl);
+	gfs2_glmutex_lock(gl);
+
+	gfs2_assert(gl->gl_sbd, atomic_read(&gl->gl_lvb_count) > 0);
+	if (atomic_dec_and_test(&gl->gl_lvb_count)) {
+		gfs2_lm_unhold_lvb(gl->gl_sbd, gl->gl_lock, gl->gl_lvb);
+		gl->gl_lvb = NULL;
+		gfs2_glock_put(gl);
+	}
+
+	gfs2_glmutex_unlock(gl);
+	gfs2_glock_put(gl);
+}
+
+void gfs2_lvb_sync(struct gfs2_glock *gl)
+{
+	gfs2_glmutex_lock(gl);
+
+	gfs2_assert(gl->gl_sbd, atomic_read(&gl->gl_lvb_count));
+	if (!gfs2_assert_warn(gl->gl_sbd, gfs2_glock_is_held_excl(gl)))
+		gfs2_lm_sync_lvb(gl->gl_sbd, gl->gl_lock, gl->gl_lvb);
+
+	gfs2_glmutex_unlock(gl);
+}
+
+static void blocking_cb(struct gfs2_sbd *sdp, struct lm_lockname *name,
+			unsigned int state)
+{
+	struct gfs2_glock *gl;
+
+	gl = gfs2_glock_find(sdp, name);
+	if (!gl)
+		return;
+
+	if (gl->gl_ops->go_callback)
+		gl->gl_ops->go_callback(gl, state);
+	handle_callback(gl, state);
+
+	spin_lock(&gl->gl_spin);
+	run_queue(gl);
+	spin_unlock(&gl->gl_spin);
+
+	gfs2_glock_put(gl);
+}
+
+/**
+ * gfs2_glock_cb - Callback used by locking module
+ * @fsdata: Pointer to the superblock
+ * @type: Type of callback
+ * @data: Type dependent data pointer
+ *
+ * Called by the locking module when it wants to tell us something.
+ * Either we need to drop a lock, one of our ASYNC requests completed, or
+ * a journal from another client needs to be recovered.
+ */
+
+void gfs2_glock_cb(lm_fsdata_t *fsdata, unsigned int type, void *data)
+{
+	struct gfs2_sbd *sdp = (struct gfs2_sbd *)fsdata;
+
+	atomic_inc(&sdp->sd_lm_callbacks);
+
+	switch (type) {
+	case LM_CB_NEED_E:
+		blocking_cb(sdp, (struct lm_lockname *)data, LM_ST_UNLOCKED);
+		return;
+
+	case LM_CB_NEED_D:
+		blocking_cb(sdp, (struct lm_lockname *)data, LM_ST_DEFERRED);
+		return;
+
+	case LM_CB_NEED_S:
+		blocking_cb(sdp, (struct lm_lockname *)data, LM_ST_SHARED);
+		return;
+
+	case LM_CB_ASYNC: {
+		struct lm_async_cb *async = (struct lm_async_cb *)data;
+		struct gfs2_glock *gl;
+
+		gl = gfs2_glock_find(sdp, &async->lc_name);
+		if (gfs2_assert_warn(sdp, gl))
+			return;
+		if (!gfs2_assert_warn(sdp, gl->gl_req_bh))
+			gl->gl_req_bh(gl, async->lc_ret);
+		gfs2_glock_put(gl);
+
+		return;
+	}
+
+	case LM_CB_NEED_RECOVERY:
+		gfs2_jdesc_make_dirty(sdp, *(unsigned int *)data);
+		if (sdp->sd_recoverd_process)
+			wake_up_process(sdp->sd_recoverd_process);
+		return;
+
+	case LM_CB_DROPLOCKS:
+		gfs2_gl_hash_clear(sdp, NO_WAIT);
+		gfs2_quota_scan(sdp);
+		return;
+
+	default:
+		gfs2_assert_warn(sdp, 0);
+		return;
+	}
+}
+
+/**
+ * gfs2_try_toss_inode - try to remove a particular inode struct from cache
+ * sdp: the filesystem
+ * inum: the inode number
+ *
+ */
+
+void gfs2_try_toss_inode(struct gfs2_sbd *sdp, struct gfs2_inum *inum)
+{
+	struct gfs2_glock *gl;
+	struct gfs2_inode *ip;
+	int error;
+
+	error = gfs2_glock_get(sdp, inum->no_addr, &gfs2_inode_glops,
+			       NO_CREATE, &gl);
+	if (error || !gl)
+		return;
+
+	if (!gfs2_glmutex_trylock(gl))
+		goto out;
+
+	ip = get_gl2ip(gl);
+	if (!ip)
+		goto out_unlock;
+
+	if (atomic_read(&ip->i_count))
+		goto out_unlock;
+
+	gfs2_inode_destroy(ip);
+
+ out_unlock:
+	gfs2_glmutex_unlock(gl);
+
+ out:
+	gfs2_glock_put(gl);
+}
+
+/**
+ * gfs2_iopen_go_callback - Try to kick the inode/vnode associated with an
+ *                          iopen glock from memory
+ * @io_gl: the iopen glock
+ * @state: the state into which the glock should be put
+ *
+ */
+
+void gfs2_iopen_go_callback(struct gfs2_glock *io_gl, unsigned int state)
+{
+	struct gfs2_glock *i_gl;
+
+	if (state != LM_ST_UNLOCKED)
+		return;
+
+	spin_lock(&io_gl->gl_spin);
+	i_gl = get_gl2gl(io_gl);
+	if (i_gl) {
+		gfs2_glock_hold(i_gl);
+		spin_unlock(&io_gl->gl_spin);
+	} else {
+		spin_unlock(&io_gl->gl_spin);
+		return;
+	}
+
+	if (gfs2_glmutex_trylock(i_gl)) {
+		struct gfs2_inode *ip = get_gl2ip(i_gl);
+		if (ip) {
+			gfs2_try_toss_vnode(ip);
+			gfs2_glmutex_unlock(i_gl);
+			gfs2_glock_schedule_for_reclaim(i_gl);
+			goto out;
+		}
+		gfs2_glmutex_unlock(i_gl);
+	}
+
+ out:
+	gfs2_glock_put(i_gl);
+}
+
+/**
+ * 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(struct gfs2_glock *gl)
+{
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct gfs2_glock_operations *glops = gl->gl_ops;
+	int demote = 1;
+
+	if (test_bit(GLF_STICKY, &gl->gl_flags))
+		demote = 0;
+	else if (test_bit(GLF_PREFETCH, &gl->gl_flags))
+		demote = time_after_eq(jiffies,
+				    gl->gl_stamp +
+				    gfs2_tune_get(sdp, gt_prefetch_secs) * HZ);
+	else if (glops->go_demote_ok)
+		demote = glops->go_demote_ok(gl);
+
+	return demote;
+}
+
+/**
+ * gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
+ * @gl: the glock
+ *
+ */
+
+void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
+{
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+
+	spin_lock(&sdp->sd_reclaim_lock);
+	if (list_empty(&gl->gl_reclaim)) {
+		gfs2_glock_hold(gl);
+		list_add(&gl->gl_reclaim, &sdp->sd_reclaim_list);
+		atomic_inc(&sdp->sd_reclaim_count);
+	}
+	spin_unlock(&sdp->sd_reclaim_lock);
+
+	wake_up(&sdp->sd_reclaim_wq);
+}
+
+/**
+ * gfs2_reclaim_glock - process the next glock on the filesystem's reclaim list
+ * @sdp: the filesystem
+ *
+ * Called from gfs2_glockd() glock reclaim daemon, or when promoting a
+ * different glock and we notice that there are a lot of glocks in the
+ * reclaim list.
+ *
+ */
+
+void gfs2_reclaim_glock(struct gfs2_sbd *sdp)
+{
+	struct gfs2_glock *gl;
+
+	spin_lock(&sdp->sd_reclaim_lock);
+	if (list_empty(&sdp->sd_reclaim_list)) {
+		spin_unlock(&sdp->sd_reclaim_lock);
+		return;
+	}
+	gl = list_entry(sdp->sd_reclaim_list.next,
+			struct gfs2_glock, gl_reclaim);
+	list_del_init(&gl->gl_reclaim);
+	spin_unlock(&sdp->sd_reclaim_lock);
+
+	atomic_dec(&sdp->sd_reclaim_count);
+	atomic_inc(&sdp->sd_reclaimed);
+
+	if (gfs2_glmutex_trylock(gl)) {
+		if (gl->gl_ops == &gfs2_inode_glops) {
+			struct gfs2_inode *ip = get_gl2ip(gl);
+			if (ip && !atomic_read(&ip->i_count))
+				gfs2_inode_destroy(ip);
+		}
+		if (queue_empty(gl, &gl->gl_holders) &&
+		    gl->gl_state != LM_ST_UNLOCKED &&
+		    demote_ok(gl))
+			handle_callback(gl, LM_ST_UNLOCKED);
+		gfs2_glmutex_unlock(gl);
+	}
+
+	gfs2_glock_put(gl);
+}
+
+/**
+ * examine_bucket - Call a function for glock in a hash bucket
+ * @examiner: the function
+ * @sdp: the filesystem
+ * @bucket: the bucket
+ *
+ * Returns: 1 if the bucket has entries
+ */
+
+static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp,
+			  struct gfs2_gl_hash_bucket *bucket)
+{
+	struct glock_plug plug;
+	struct list_head *tmp;
+	struct gfs2_glock *gl;
+	int entries;
+
+	/* Add "plug" to end of bucket list, work back up list from there */
+	memset(&plug.gl_flags, 0, sizeof(unsigned long));
+	set_bit(GLF_PLUG, &plug.gl_flags);
+
+	write_lock(&bucket->hb_lock);
+	list_add(&plug.gl_list, &bucket->hb_list);
+	write_unlock(&bucket->hb_lock);
+
+	for (;;) {
+		write_lock(&bucket->hb_lock);
+
+		for (;;) {
+			tmp = plug.gl_list.next;
+
+			if (tmp == &bucket->hb_list) {
+				list_del(&plug.gl_list);
+				entries = !list_empty(&bucket->hb_list);
+				write_unlock(&bucket->hb_lock);
+				return entries;
+			}
+			gl = list_entry(tmp, struct gfs2_glock, gl_list);
+
+			/* Move plug up list */
+			list_move(&plug.gl_list, &gl->gl_list);
+
+			if (test_bit(GLF_PLUG, &gl->gl_flags))
+				continue;
+
+			/* examiner() must glock_put() */
+			gfs2_glock_hold(gl);
+
+			break;
+		}
+
+		write_unlock(&bucket->hb_lock);
+
+		examiner(gl);
+	}
+}
+
+/**
+ * scan_glock - look at a glock and see if we can reclaim it
+ * @gl: the glock to look at
+ *
+ */
+
+static void scan_glock(struct gfs2_glock *gl)
+{
+	if (gfs2_glmutex_trylock(gl)) {
+		if (gl->gl_ops == &gfs2_inode_glops) {
+			struct gfs2_inode *ip = get_gl2ip(gl);
+			if (ip && !atomic_read(&ip->i_count))
+				goto out_schedule;
+		}
+		if (queue_empty(gl, &gl->gl_holders) &&
+		    gl->gl_state != LM_ST_UNLOCKED &&
+		    demote_ok(gl))
+			goto out_schedule;
+
+		gfs2_glmutex_unlock(gl);
+	}
+
+	gfs2_glock_put(gl);
+
+	return;
+
+ out_schedule:
+	gfs2_glmutex_unlock(gl);
+	gfs2_glock_schedule_for_reclaim(gl);
+	gfs2_glock_put(gl);
+}
+
+/**
+ * gfs2_scand_internal - Look for glocks and inodes to toss from memory
+ * @sdp: the filesystem
+ *
+ */
+
+void gfs2_scand_internal(struct gfs2_sbd *sdp)
+{
+	unsigned int x;
+
+	for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
+		examine_bucket(scan_glock, sdp, &sdp->sd_gl_hash[x]);
+		cond_resched();
+	}
+}
+
+/**
+ * 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)
+{
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	int released;
+
+	spin_lock(&sdp->sd_reclaim_lock);
+	if (!list_empty(&gl->gl_reclaim)) {
+		list_del_init(&gl->gl_reclaim);
+		atomic_dec(&sdp->sd_reclaim_count);
+		released = gfs2_glock_put(gl);
+		gfs2_assert(sdp, !released);
+	}
+	spin_unlock(&sdp->sd_reclaim_lock);
+
+	if (gfs2_glmutex_trylock(gl)) {
+		if (gl->gl_ops == &gfs2_inode_glops) {
+			struct gfs2_inode *ip = get_gl2ip(gl);
+			if (ip && !atomic_read(&ip->i_count))
+				gfs2_inode_destroy(ip);
+		}
+		if (queue_empty(gl, &gl->gl_holders) &&
+		    gl->gl_state != LM_ST_UNLOCKED)
+			handle_callback(gl, LM_ST_UNLOCKED);
+
+		gfs2_glmutex_unlock(gl);
+	}
+
+	gfs2_glock_put(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, or when inter-node lock manager
+ * requests DROPLOCKS because it is running out of capacity.
+ */
+
+void gfs2_gl_hash_clear(struct gfs2_sbd *sdp, int wait)
+{
+	unsigned long t;
+	unsigned int x;
+	int cont;
+
+	t = jiffies;
+
+	for (;;) {
+		cont = 0;
+
+		for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
+			if (examine_bucket(clear_glock, sdp,
+					   &sdp->sd_gl_hash[x]))
+				cont = 1;
+
+		if (!wait || !cont)
+			break;
+
+		if (time_after_eq(jiffies,
+				  t + gfs2_tune_get(sdp, gt_stall_secs) * HZ)) {
+			fs_warn(sdp, "Unmount seems to be stalled. "
+				     "Dumping lock state...\n");
+			gfs2_dump_lockstate(sdp, NULL);
+			t = jiffies;
+		}
+
+		invalidate_inodes(sdp->sd_vfs);
+		yield();
+	}
+}
+
+/*
+ *  Diagnostic routines to help debug distributed deadlock
+ */
+
+/**
+ * dump_holder - print information about a glock holder
+ * @str: a string naming the type of holder
+ * @gh: the glock holder
+ * @buf: the buffer
+ * @size: the size of the buffer
+ * @count: where we are in the buffer
+ *
+ * Returns: 0 on success, -ENOBUFS when we run out of space
+ */
+
+static int dump_holder(char *str, struct gfs2_holder *gh, char *buf,
+		       unsigned int size, unsigned int *count)
+{
+	unsigned int x;
+	int error = -ENOBUFS;
+
+	gfs2_printf("  %s\n", str);
+	gfs2_printf("    owner = %ld\n",
+		   (gh->gh_owner) ? (long)gh->gh_owner->pid : -1);
+	gfs2_printf("    gh_state = %u\n", gh->gh_state);
+	gfs2_printf("    gh_flags =");
+	for (x = 0; x < 32; x++)
+		if (gh->gh_flags & (1 << x))
+			gfs2_printf(" %u", x);
+	gfs2_printf(" \n");
+	gfs2_printf("    error = %d\n", gh->gh_error);
+	gfs2_printf("    gh_iflags =");
+	for (x = 0; x < 32; x++)
+		if (test_bit(x, &gh->gh_iflags))
+			gfs2_printf(" %u", x);
+	gfs2_printf(" \n");
+
+	error = 0;
+
+ out:
+	return error;
+}
+
+/**
+ * dump_inode - print information about an inode
+ * @ip: the inode
+ * @buf: the buffer
+ * @size: the size of the buffer
+ * @count: where we are in the buffer
+ *
+ * Returns: 0 on success, -ENOBUFS when we run out of space
+ */
+
+static int dump_inode(struct gfs2_inode *ip, char *buf, unsigned int size,
+		      unsigned int *count)
+{
+	unsigned int x;
+	int error = -ENOBUFS;
+
+	gfs2_printf("  Inode:\n");
+	gfs2_printf("    num = %llu %llu\n",
+		    ip->i_num.no_formal_ino, ip->i_num.no_addr);
+	gfs2_printf("    type = %u\n", IF2DT(ip->i_di.di_mode));
+	gfs2_printf("    i_count = %d\n", atomic_read(&ip->i_count));
+	gfs2_printf("    i_flags =");
+	for (x = 0; x < 32; x++)
+		if (test_bit(x, &ip->i_flags))
+			gfs2_printf(" %u", x);
+	gfs2_printf(" \n");
+	gfs2_printf("    vnode = %s\n", (ip->i_vnode) ? "yes" : "no");
+
+	error = 0;
+
+ out:
+	return error;
+}
+
+/**
+ * dump_glock - print information about a glock
+ * @gl: the glock
+ * @buf: the buffer
+ * @size: the size of the buffer
+ * @count: where we are in the buffer
+ *
+ * Returns: 0 on success, -ENOBUFS when we run out of space
+ */
+
+static int dump_glock(struct gfs2_glock *gl, char *buf, unsigned int size,
+		      unsigned int *count)
+{
+	struct gfs2_holder *gh;
+	unsigned int x;
+	int error = -ENOBUFS;
+
+	spin_lock(&gl->gl_spin);
+
+	gfs2_printf("Glock (%u, %llu)\n",
+		    gl->gl_name.ln_type,
+		    gl->gl_name.ln_number);
+	gfs2_printf("  gl_flags =");
+	for (x = 0; x < 32; x++)
+		if (test_bit(x, &gl->gl_flags))
+			gfs2_printf(" %u", x);
+	gfs2_printf(" \n");
+	gfs2_printf("  gl_ref = %d\n", atomic_read(&gl->gl_ref.refcount));
+	gfs2_printf("  gl_state = %u\n", gl->gl_state);
+	gfs2_printf("  req_gh = %s\n", (gl->gl_req_gh) ? "yes" : "no");
+	gfs2_printf("  req_bh = %s\n", (gl->gl_req_bh) ? "yes" : "no");
+	gfs2_printf("  lvb_count = %d\n", atomic_read(&gl->gl_lvb_count));
+	gfs2_printf("  object = %s\n", (gl->gl_object) ? "yes" : "no");
+	gfs2_printf("  le = %s\n",
+		   (list_empty(&gl->gl_le.le_list)) ? "no" : "yes");
+	gfs2_printf("  reclaim = %s\n",
+		    (list_empty(&gl->gl_reclaim)) ? "no" : "yes");
+	if (gl->gl_aspace)
+		gfs2_printf("  aspace = %lu\n",
+			    gl->gl_aspace->i_mapping->nrpages);
+	else
+		gfs2_printf("  aspace = no\n");
+	gfs2_printf("  ail = %d\n", atomic_read(&gl->gl_ail_count));
+	if (gl->gl_req_gh) {
+		error = dump_holder("Request", gl->gl_req_gh, buf, size, count);
+		if (error)
+			goto out;
+	}
+	list_for_each_entry(gh, &gl->gl_holders, gh_list) {
+		error = dump_holder("Holder", gh, buf, size, count);
+		if (error)
+			goto out;
+	}
+	list_for_each_entry(gh, &gl->gl_waiters1, gh_list) {
+		error = dump_holder("Waiter1", gh, buf, size, count);
+		if (error)
+			goto out;
+	}
+	list_for_each_entry(gh, &gl->gl_waiters2, gh_list) {
+		error = dump_holder("Waiter2", gh, buf, size, count);
+		if (error)
+			goto out;
+	}
+	list_for_each_entry(gh, &gl->gl_waiters3, gh_list) {
+		error = dump_holder("Waiter3", gh, buf, size, count);
+		if (error)
+			goto out;
+	}
+	if (gl->gl_ops == &gfs2_inode_glops && get_gl2ip(gl)) {
+		if (!test_bit(GLF_LOCK, &gl->gl_flags) &&
+		    list_empty(&gl->gl_holders)) {
+			error = dump_inode(get_gl2ip(gl), buf, size, count);
+			if (error)
+				goto out;
+		} else {
+			error = -ENOBUFS;
+			gfs2_printf("  Inode: busy\n");
+		}
+	}
+
+	error = 0;
+
+ out:
+	spin_unlock(&gl->gl_spin);
+
+	return error;
+}
+
+/**
+ * gfs2_dump_lockstate - print out the current lockstate
+ * @sdp: the filesystem
+ * @ub: the buffer to copy the information into
+ *
+ * If @ub is NULL, dump the lockstate to the console.
+ *
+ */
+
+int gfs2_dump_lockstate(struct gfs2_sbd *sdp, struct gfs2_user_buffer *ub)
+{
+	struct gfs2_gl_hash_bucket *bucket;
+	struct gfs2_glock *gl;
+	char *buf = NULL;
+	unsigned int size = gfs2_tune_get(sdp, gt_lockdump_size);
+	unsigned int x, count;
+	int error = 0;
+
+	if (ub) {
+		buf = kmalloc(size, GFP_KERNEL);
+		if (!buf)
+			return -ENOMEM;
+	}
+
+	for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
+		bucket = &sdp->sd_gl_hash[x];
+		count = 0;
+
+		read_lock(&bucket->hb_lock);
+
+		list_for_each_entry(gl, &bucket->hb_list, gl_list) {
+			if (test_bit(GLF_PLUG, &gl->gl_flags))
+				continue;
+
+			error = dump_glock(gl, buf, size, &count);
+			if (error)
+				break;
+		}
+
+		read_unlock(&bucket->hb_lock);
+
+		if (error)
+			break;
+
+		if (ub) {
+			if (ub->ub_count + count > ub->ub_size) {
+				error = -ENOMEM;
+				break;
+			}
+			if (copy_to_user(ub->ub_data + ub->ub_count, buf,
+					 count)) {
+				error = -EFAULT;
+				break;
+			}
+			ub->ub_count += count;
+		}
+	}
+
+	kfree(buf);
+
+	return error;
+}
+

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