[GFS2] The core of GFS2

This patch contains all the core files for GFS2.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 2513 insertions, 0 deletions

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
new file mode 100644
index 000000000000..321945fde12d
--- /dev/null
+++ b/fs/gfs2/glock.c
@@ -0,0 +1,2513 @@
+/*
+ * 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_sbd *sdp = gl->gl_sbd;
+        struct gfs2_gl_hash_bucket *bucket = gl->gl_bucket;
+        int rv = 0;
+
+        down(&sdp->sd_invalidate_inodes_mutex);
+
+        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);
+                rv = 1;
+                goto out;
+        }
+        write_unlock(&bucket->hb_lock);
+ out:
+        up(&sdp->sd_invalidate_inodes_mutex);
+        return rv;
+}
+
+/**
+ * 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, gfp_t 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;
+
+        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 gh->gh_error;
+                }
+                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) {
+                        gh->gh_error = glops->go_lock(gh);
+                        if (gh->gh_error) {
+                                spin_lock(&gl->gl_spin);
+                                list_del_init(&gh->gh_list);
+                                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 gh->gh_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);
+                        t = jiffies;
+                }
+
+                /* invalidate_inodes() requires that the sb inodes list
+                   not change, but an async completion callback for an
+                   unlock can occur which does glock_put() which
+                   can call iput() which will change the sb inodes list.
+                   invalidate_inodes_mutex prevents glock_put()'s during
+                   an invalidate_inodes() */
+
+                down(&sdp->sd_invalidate_inodes_mutex);
+                invalidate_inodes(sdp->sd_vfs);
+                up(&sdp->sd_invalidate_inodes_mutex);
+                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
+ *
+ * Returns: 0 on success, -ENOBUFS when we run out of space
+ */
+
+static int dump_holder(char *str, struct gfs2_holder *gh)
+{
+        unsigned int x;
+        int error = -ENOBUFS;
+
+        printk("  %s\n", str);
+        printk("    owner = %ld\n",
+                   (gh->gh_owner) ? (long)gh->gh_owner->pid : -1);
+        printk("    gh_state = %u\n", gh->gh_state);
+        printk("    gh_flags =");
+        for (x = 0; x < 32; x++)
+                if (gh->gh_flags & (1 << x))
+                        printk(" %u", x);
+        printk(" \n");
+        printk("    error = %d\n", gh->gh_error);
+        printk("    gh_iflags =");
+        for (x = 0; x < 32; x++)
+                if (test_bit(x, &gh->gh_iflags))
+                        printk(" %u", x);
+        printk(" \n");
+
+        error = 0;
+
+        return error;
+}
+
+/**
+ * dump_inode - print information about an inode
+ * @ip: the inode
+ *
+ * Returns: 0 on success, -ENOBUFS when we run out of space
+ */
+
+static int dump_inode(struct gfs2_inode *ip)
+{
+        unsigned int x;
+        int error = -ENOBUFS;
+
+        printk("  Inode:\n");
+        printk("    num = %llu %llu\n",
+                    ip->i_num.no_formal_ino, ip->i_num.no_addr);
+        printk("    type = %u\n", IF2DT(ip->i_di.di_mode));
+        printk("    i_count = %d\n", atomic_read(&ip->i_count));
+        printk("    i_flags =");
+        for (x = 0; x < 32; x++)
+                if (test_bit(x, &ip->i_flags))
+                        printk(" %u", x);
+        printk(" \n");
+        printk("    vnode = %s\n", (ip->i_vnode) ? "yes" : "no");
+
+        error = 0;
+
+        return error;
+}
+
+/**
+ * dump_glock - print information about a glock
+ * @gl: the glock
+ * @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)
+{
+        struct gfs2_holder *gh;
+        unsigned int x;
+        int error = -ENOBUFS;
+
+        spin_lock(&gl->gl_spin);
+
+        printk("Glock (%u, %llu)\n",
+                    gl->gl_name.ln_type,
+                    gl->gl_name.ln_number);
+        printk("  gl_flags =");
+        for (x = 0; x < 32; x++)
+                if (test_bit(x, &gl->gl_flags))
+                        printk(" %u", x);
+        printk(" \n");
+        printk("  gl_ref = %d\n", atomic_read(&gl->gl_ref.refcount));
+        printk("  gl_state = %u\n", gl->gl_state);
+        printk("  req_gh = %s\n", (gl->gl_req_gh) ? "yes" : "no");
+        printk("  req_bh = %s\n", (gl->gl_req_bh) ? "yes" : "no");
+        printk("  lvb_count = %d\n", atomic_read(&gl->gl_lvb_count));
+        printk("  object = %s\n", (gl->gl_object) ? "yes" : "no");
+        printk("  le = %s\n",
+                   (list_empty(&gl->gl_le.le_list)) ? "no" : "yes");
+        printk("  reclaim = %s\n",
+                    (list_empty(&gl->gl_reclaim)) ? "no" : "yes");
+        if (gl->gl_aspace)
+                printk("  aspace = %lu\n",
+                            gl->gl_aspace->i_mapping->nrpages);
+        else
+                printk("  aspace = no\n");
+        printk("  ail = %d\n", atomic_read(&gl->gl_ail_count));
+        if (gl->gl_req_gh) {
+                error = dump_holder("Request", gl->gl_req_gh);
+                if (error)
+                        goto out;
+        }
+        list_for_each_entry(gh, &gl->gl_holders, gh_list) {
+                error = dump_holder("Holder", gh);
+                if (error)
+                        goto out;
+        }
+        list_for_each_entry(gh, &gl->gl_waiters1, gh_list) {
+                error = dump_holder("Waiter1", gh);
+                if (error)
+                        goto out;
+        }
+        list_for_each_entry(gh, &gl->gl_waiters2, gh_list) {
+                error = dump_holder("Waiter2", gh);
+                if (error)
+                        goto out;
+        }
+        list_for_each_entry(gh, &gl->gl_waiters3, gh_list) {
+                error = dump_holder("Waiter3", gh);
+                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));
+                        if (error)
+                                goto out;
+                } else {
+                        error = -ENOBUFS;
+                        printk("  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_gl_hash_bucket *bucket;
+        struct gfs2_glock *gl;
+        unsigned int x;
+        int error = 0;
+
+        for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
+                bucket = &sdp->sd_gl_hash[x];
+
+                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);
+                        if (error)
+                                break;
+                }
+
+                read_unlock(&bucket->hb_lock);
+
+                if (error)
+                        break;
+        }
+
+
+        return error;
+}
+