linux/fs/dlm/debug_fs.c
Alexander Aring 5b2f981fde fs: dlm: add midcomms debugfs functionality
This patch adds functionality to debug midcomms per connection state
inside a comms directory which is similar like dlm configfs. Currently
there exists the possibility to read out two attributes which is the
send queue counter and the version of each midcomms node state.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2021-05-25 09:22:20 -05:00

861 lines
20 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/******************************************************************************
*******************************************************************************
**
** Copyright (C) 2005-2009 Red Hat, Inc. All rights reserved.
**
**
*******************************************************************************
******************************************************************************/
#include <linux/pagemap.h>
#include <linux/seq_file.h>
#include <linux/init.h>
#include <linux/ctype.h>
#include <linux/debugfs.h>
#include <linux/slab.h>
#include "dlm_internal.h"
#include "midcomms.h"
#include "lock.h"
#define DLM_DEBUG_BUF_LEN 4096
static char debug_buf[DLM_DEBUG_BUF_LEN];
static struct mutex debug_buf_lock;
static struct dentry *dlm_root;
static struct dentry *dlm_comms;
static char *print_lockmode(int mode)
{
switch (mode) {
case DLM_LOCK_IV:
return "--";
case DLM_LOCK_NL:
return "NL";
case DLM_LOCK_CR:
return "CR";
case DLM_LOCK_CW:
return "CW";
case DLM_LOCK_PR:
return "PR";
case DLM_LOCK_PW:
return "PW";
case DLM_LOCK_EX:
return "EX";
default:
return "??";
}
}
static void print_format1_lock(struct seq_file *s, struct dlm_lkb *lkb,
struct dlm_rsb *res)
{
seq_printf(s, "%08x %s", lkb->lkb_id, print_lockmode(lkb->lkb_grmode));
if (lkb->lkb_status == DLM_LKSTS_CONVERT ||
lkb->lkb_status == DLM_LKSTS_WAITING)
seq_printf(s, " (%s)", print_lockmode(lkb->lkb_rqmode));
if (lkb->lkb_nodeid) {
if (lkb->lkb_nodeid != res->res_nodeid)
seq_printf(s, " Remote: %3d %08x", lkb->lkb_nodeid,
lkb->lkb_remid);
else
seq_printf(s, " Master: %08x", lkb->lkb_remid);
}
if (lkb->lkb_wait_type)
seq_printf(s, " wait_type: %d", lkb->lkb_wait_type);
seq_putc(s, '\n');
}
static void print_format1(struct dlm_rsb *res, struct seq_file *s)
{
struct dlm_lkb *lkb;
int i, lvblen = res->res_ls->ls_lvblen, recover_list, root_list;
lock_rsb(res);
seq_printf(s, "\nResource %p Name (len=%d) \"", res, res->res_length);
for (i = 0; i < res->res_length; i++) {
if (isprint(res->res_name[i]))
seq_printf(s, "%c", res->res_name[i]);
else
seq_printf(s, "%c", '.');
}
if (res->res_nodeid > 0)
seq_printf(s, "\"\nLocal Copy, Master is node %d\n",
res->res_nodeid);
else if (res->res_nodeid == 0)
seq_puts(s, "\"\nMaster Copy\n");
else if (res->res_nodeid == -1)
seq_printf(s, "\"\nLooking up master (lkid %x)\n",
res->res_first_lkid);
else
seq_printf(s, "\"\nInvalid master %d\n", res->res_nodeid);
if (seq_has_overflowed(s))
goto out;
/* Print the LVB: */
if (res->res_lvbptr) {
seq_puts(s, "LVB: ");
for (i = 0; i < lvblen; i++) {
if (i == lvblen / 2)
seq_puts(s, "\n ");
seq_printf(s, "%02x ",
(unsigned char) res->res_lvbptr[i]);
}
if (rsb_flag(res, RSB_VALNOTVALID))
seq_puts(s, " (INVALID)");
seq_putc(s, '\n');
if (seq_has_overflowed(s))
goto out;
}
root_list = !list_empty(&res->res_root_list);
recover_list = !list_empty(&res->res_recover_list);
if (root_list || recover_list) {
seq_printf(s, "Recovery: root %d recover %d flags %lx count %d\n",
root_list, recover_list,
res->res_flags, res->res_recover_locks_count);
}
/* Print the locks attached to this resource */
seq_puts(s, "Granted Queue\n");
list_for_each_entry(lkb, &res->res_grantqueue, lkb_statequeue) {
print_format1_lock(s, lkb, res);
if (seq_has_overflowed(s))
goto out;
}
seq_puts(s, "Conversion Queue\n");
list_for_each_entry(lkb, &res->res_convertqueue, lkb_statequeue) {
print_format1_lock(s, lkb, res);
if (seq_has_overflowed(s))
goto out;
}
seq_puts(s, "Waiting Queue\n");
list_for_each_entry(lkb, &res->res_waitqueue, lkb_statequeue) {
print_format1_lock(s, lkb, res);
if (seq_has_overflowed(s))
goto out;
}
if (list_empty(&res->res_lookup))
goto out;
seq_puts(s, "Lookup Queue\n");
list_for_each_entry(lkb, &res->res_lookup, lkb_rsb_lookup) {
seq_printf(s, "%08x %s",
lkb->lkb_id, print_lockmode(lkb->lkb_rqmode));
if (lkb->lkb_wait_type)
seq_printf(s, " wait_type: %d", lkb->lkb_wait_type);
seq_putc(s, '\n');
if (seq_has_overflowed(s))
goto out;
}
out:
unlock_rsb(res);
}
static void print_format2_lock(struct seq_file *s, struct dlm_lkb *lkb,
struct dlm_rsb *r)
{
u64 xid = 0;
u64 us;
if (lkb->lkb_flags & DLM_IFL_USER) {
if (lkb->lkb_ua)
xid = lkb->lkb_ua->xid;
}
/* microseconds since lkb was added to current queue */
us = ktime_to_us(ktime_sub(ktime_get(), lkb->lkb_timestamp));
/* id nodeid remid pid xid exflags flags sts grmode rqmode time_us
r_nodeid r_len r_name */
seq_printf(s, "%x %d %x %u %llu %x %x %d %d %d %llu %u %d \"%s\"\n",
lkb->lkb_id,
lkb->lkb_nodeid,
lkb->lkb_remid,
lkb->lkb_ownpid,
(unsigned long long)xid,
lkb->lkb_exflags,
lkb->lkb_flags,
lkb->lkb_status,
lkb->lkb_grmode,
lkb->lkb_rqmode,
(unsigned long long)us,
r->res_nodeid,
r->res_length,
r->res_name);
}
static void print_format2(struct dlm_rsb *r, struct seq_file *s)
{
struct dlm_lkb *lkb;
lock_rsb(r);
list_for_each_entry(lkb, &r->res_grantqueue, lkb_statequeue) {
print_format2_lock(s, lkb, r);
if (seq_has_overflowed(s))
goto out;
}
list_for_each_entry(lkb, &r->res_convertqueue, lkb_statequeue) {
print_format2_lock(s, lkb, r);
if (seq_has_overflowed(s))
goto out;
}
list_for_each_entry(lkb, &r->res_waitqueue, lkb_statequeue) {
print_format2_lock(s, lkb, r);
if (seq_has_overflowed(s))
goto out;
}
out:
unlock_rsb(r);
}
static void print_format3_lock(struct seq_file *s, struct dlm_lkb *lkb,
int rsb_lookup)
{
u64 xid = 0;
if (lkb->lkb_flags & DLM_IFL_USER) {
if (lkb->lkb_ua)
xid = lkb->lkb_ua->xid;
}
seq_printf(s, "lkb %x %d %x %u %llu %x %x %d %d %d %d %d %d %u %llu %llu\n",
lkb->lkb_id,
lkb->lkb_nodeid,
lkb->lkb_remid,
lkb->lkb_ownpid,
(unsigned long long)xid,
lkb->lkb_exflags,
lkb->lkb_flags,
lkb->lkb_status,
lkb->lkb_grmode,
lkb->lkb_rqmode,
lkb->lkb_last_bast.mode,
rsb_lookup,
lkb->lkb_wait_type,
lkb->lkb_lvbseq,
(unsigned long long)ktime_to_ns(lkb->lkb_timestamp),
(unsigned long long)ktime_to_ns(lkb->lkb_last_bast_time));
}
static void print_format3(struct dlm_rsb *r, struct seq_file *s)
{
struct dlm_lkb *lkb;
int i, lvblen = r->res_ls->ls_lvblen;
int print_name = 1;
lock_rsb(r);
seq_printf(s, "rsb %p %d %x %lx %d %d %u %d ",
r,
r->res_nodeid,
r->res_first_lkid,
r->res_flags,
!list_empty(&r->res_root_list),
!list_empty(&r->res_recover_list),
r->res_recover_locks_count,
r->res_length);
if (seq_has_overflowed(s))
goto out;
for (i = 0; i < r->res_length; i++) {
if (!isascii(r->res_name[i]) || !isprint(r->res_name[i]))
print_name = 0;
}
seq_puts(s, print_name ? "str " : "hex");
for (i = 0; i < r->res_length; i++) {
if (print_name)
seq_printf(s, "%c", r->res_name[i]);
else
seq_printf(s, " %02x", (unsigned char)r->res_name[i]);
}
seq_putc(s, '\n');
if (seq_has_overflowed(s))
goto out;
if (!r->res_lvbptr)
goto do_locks;
seq_printf(s, "lvb %u %d", r->res_lvbseq, lvblen);
for (i = 0; i < lvblen; i++)
seq_printf(s, " %02x", (unsigned char)r->res_lvbptr[i]);
seq_putc(s, '\n');
if (seq_has_overflowed(s))
goto out;
do_locks:
list_for_each_entry(lkb, &r->res_grantqueue, lkb_statequeue) {
print_format3_lock(s, lkb, 0);
if (seq_has_overflowed(s))
goto out;
}
list_for_each_entry(lkb, &r->res_convertqueue, lkb_statequeue) {
print_format3_lock(s, lkb, 0);
if (seq_has_overflowed(s))
goto out;
}
list_for_each_entry(lkb, &r->res_waitqueue, lkb_statequeue) {
print_format3_lock(s, lkb, 0);
if (seq_has_overflowed(s))
goto out;
}
list_for_each_entry(lkb, &r->res_lookup, lkb_rsb_lookup) {
print_format3_lock(s, lkb, 1);
if (seq_has_overflowed(s))
goto out;
}
out:
unlock_rsb(r);
}
static void print_format4(struct dlm_rsb *r, struct seq_file *s)
{
int our_nodeid = dlm_our_nodeid();
int print_name = 1;
int i;
lock_rsb(r);
seq_printf(s, "rsb %p %d %d %d %d %lu %lx %d ",
r,
r->res_nodeid,
r->res_master_nodeid,
r->res_dir_nodeid,
our_nodeid,
r->res_toss_time,
r->res_flags,
r->res_length);
for (i = 0; i < r->res_length; i++) {
if (!isascii(r->res_name[i]) || !isprint(r->res_name[i]))
print_name = 0;
}
seq_puts(s, print_name ? "str " : "hex");
for (i = 0; i < r->res_length; i++) {
if (print_name)
seq_printf(s, "%c", r->res_name[i]);
else
seq_printf(s, " %02x", (unsigned char)r->res_name[i]);
}
seq_putc(s, '\n');
unlock_rsb(r);
}
struct rsbtbl_iter {
struct dlm_rsb *rsb;
unsigned bucket;
int format;
int header;
};
/*
* If the buffer is full, seq_printf can be called again, but it
* does nothing. So, the these printing routines periodically check
* seq_has_overflowed to avoid wasting too much time trying to print to
* a full buffer.
*/
static int table_seq_show(struct seq_file *seq, void *iter_ptr)
{
struct rsbtbl_iter *ri = iter_ptr;
switch (ri->format) {
case 1:
print_format1(ri->rsb, seq);
break;
case 2:
if (ri->header) {
seq_puts(seq, "id nodeid remid pid xid exflags flags sts grmode rqmode time_ms r_nodeid r_len r_name\n");
ri->header = 0;
}
print_format2(ri->rsb, seq);
break;
case 3:
if (ri->header) {
seq_puts(seq, "version rsb 1.1 lvb 1.1 lkb 1.1\n");
ri->header = 0;
}
print_format3(ri->rsb, seq);
break;
case 4:
if (ri->header) {
seq_puts(seq, "version 4 rsb 2\n");
ri->header = 0;
}
print_format4(ri->rsb, seq);
break;
}
return 0;
}
static const struct seq_operations format1_seq_ops;
static const struct seq_operations format2_seq_ops;
static const struct seq_operations format3_seq_ops;
static const struct seq_operations format4_seq_ops;
static void *table_seq_start(struct seq_file *seq, loff_t *pos)
{
struct rb_root *tree;
struct rb_node *node;
struct dlm_ls *ls = seq->private;
struct rsbtbl_iter *ri;
struct dlm_rsb *r;
loff_t n = *pos;
unsigned bucket, entry;
int toss = (seq->op == &format4_seq_ops);
bucket = n >> 32;
entry = n & ((1LL << 32) - 1);
if (bucket >= ls->ls_rsbtbl_size)
return NULL;
ri = kzalloc(sizeof(*ri), GFP_NOFS);
if (!ri)
return NULL;
if (n == 0)
ri->header = 1;
if (seq->op == &format1_seq_ops)
ri->format = 1;
if (seq->op == &format2_seq_ops)
ri->format = 2;
if (seq->op == &format3_seq_ops)
ri->format = 3;
if (seq->op == &format4_seq_ops)
ri->format = 4;
tree = toss ? &ls->ls_rsbtbl[bucket].toss : &ls->ls_rsbtbl[bucket].keep;
spin_lock(&ls->ls_rsbtbl[bucket].lock);
if (!RB_EMPTY_ROOT(tree)) {
for (node = rb_first(tree); node; node = rb_next(node)) {
r = rb_entry(node, struct dlm_rsb, res_hashnode);
if (!entry--) {
dlm_hold_rsb(r);
ri->rsb = r;
ri->bucket = bucket;
spin_unlock(&ls->ls_rsbtbl[bucket].lock);
return ri;
}
}
}
spin_unlock(&ls->ls_rsbtbl[bucket].lock);
/*
* move to the first rsb in the next non-empty bucket
*/
/* zero the entry */
n &= ~((1LL << 32) - 1);
while (1) {
bucket++;
n += 1LL << 32;
if (bucket >= ls->ls_rsbtbl_size) {
kfree(ri);
return NULL;
}
tree = toss ? &ls->ls_rsbtbl[bucket].toss : &ls->ls_rsbtbl[bucket].keep;
spin_lock(&ls->ls_rsbtbl[bucket].lock);
if (!RB_EMPTY_ROOT(tree)) {
node = rb_first(tree);
r = rb_entry(node, struct dlm_rsb, res_hashnode);
dlm_hold_rsb(r);
ri->rsb = r;
ri->bucket = bucket;
spin_unlock(&ls->ls_rsbtbl[bucket].lock);
*pos = n;
return ri;
}
spin_unlock(&ls->ls_rsbtbl[bucket].lock);
}
}
static void *table_seq_next(struct seq_file *seq, void *iter_ptr, loff_t *pos)
{
struct dlm_ls *ls = seq->private;
struct rsbtbl_iter *ri = iter_ptr;
struct rb_root *tree;
struct rb_node *next;
struct dlm_rsb *r, *rp;
loff_t n = *pos;
unsigned bucket;
int toss = (seq->op == &format4_seq_ops);
bucket = n >> 32;
/*
* move to the next rsb in the same bucket
*/
spin_lock(&ls->ls_rsbtbl[bucket].lock);
rp = ri->rsb;
next = rb_next(&rp->res_hashnode);
if (next) {
r = rb_entry(next, struct dlm_rsb, res_hashnode);
dlm_hold_rsb(r);
ri->rsb = r;
spin_unlock(&ls->ls_rsbtbl[bucket].lock);
dlm_put_rsb(rp);
++*pos;
return ri;
}
spin_unlock(&ls->ls_rsbtbl[bucket].lock);
dlm_put_rsb(rp);
/*
* move to the first rsb in the next non-empty bucket
*/
/* zero the entry */
n &= ~((1LL << 32) - 1);
while (1) {
bucket++;
n += 1LL << 32;
if (bucket >= ls->ls_rsbtbl_size) {
kfree(ri);
++*pos;
return NULL;
}
tree = toss ? &ls->ls_rsbtbl[bucket].toss : &ls->ls_rsbtbl[bucket].keep;
spin_lock(&ls->ls_rsbtbl[bucket].lock);
if (!RB_EMPTY_ROOT(tree)) {
next = rb_first(tree);
r = rb_entry(next, struct dlm_rsb, res_hashnode);
dlm_hold_rsb(r);
ri->rsb = r;
ri->bucket = bucket;
spin_unlock(&ls->ls_rsbtbl[bucket].lock);
*pos = n;
return ri;
}
spin_unlock(&ls->ls_rsbtbl[bucket].lock);
}
}
static void table_seq_stop(struct seq_file *seq, void *iter_ptr)
{
struct rsbtbl_iter *ri = iter_ptr;
if (ri) {
dlm_put_rsb(ri->rsb);
kfree(ri);
}
}
static const struct seq_operations format1_seq_ops = {
.start = table_seq_start,
.next = table_seq_next,
.stop = table_seq_stop,
.show = table_seq_show,
};
static const struct seq_operations format2_seq_ops = {
.start = table_seq_start,
.next = table_seq_next,
.stop = table_seq_stop,
.show = table_seq_show,
};
static const struct seq_operations format3_seq_ops = {
.start = table_seq_start,
.next = table_seq_next,
.stop = table_seq_stop,
.show = table_seq_show,
};
static const struct seq_operations format4_seq_ops = {
.start = table_seq_start,
.next = table_seq_next,
.stop = table_seq_stop,
.show = table_seq_show,
};
static const struct file_operations format1_fops;
static const struct file_operations format2_fops;
static const struct file_operations format3_fops;
static const struct file_operations format4_fops;
static int table_open1(struct inode *inode, struct file *file)
{
struct seq_file *seq;
int ret;
ret = seq_open(file, &format1_seq_ops);
if (ret)
return ret;
seq = file->private_data;
seq->private = inode->i_private; /* the dlm_ls */
return 0;
}
static int table_open2(struct inode *inode, struct file *file)
{
struct seq_file *seq;
int ret;
ret = seq_open(file, &format2_seq_ops);
if (ret)
return ret;
seq = file->private_data;
seq->private = inode->i_private; /* the dlm_ls */
return 0;
}
static int table_open3(struct inode *inode, struct file *file)
{
struct seq_file *seq;
int ret;
ret = seq_open(file, &format3_seq_ops);
if (ret)
return ret;
seq = file->private_data;
seq->private = inode->i_private; /* the dlm_ls */
return 0;
}
static int table_open4(struct inode *inode, struct file *file)
{
struct seq_file *seq;
int ret;
ret = seq_open(file, &format4_seq_ops);
if (ret)
return ret;
seq = file->private_data;
seq->private = inode->i_private; /* the dlm_ls */
return 0;
}
static const struct file_operations format1_fops = {
.owner = THIS_MODULE,
.open = table_open1,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release
};
static const struct file_operations format2_fops = {
.owner = THIS_MODULE,
.open = table_open2,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release
};
static const struct file_operations format3_fops = {
.owner = THIS_MODULE,
.open = table_open3,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release
};
static const struct file_operations format4_fops = {
.owner = THIS_MODULE,
.open = table_open4,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release
};
/*
* dump lkb's on the ls_waiters list
*/
static ssize_t waiters_read(struct file *file, char __user *userbuf,
size_t count, loff_t *ppos)
{
struct dlm_ls *ls = file->private_data;
struct dlm_lkb *lkb;
size_t len = DLM_DEBUG_BUF_LEN, pos = 0, ret, rv;
mutex_lock(&debug_buf_lock);
mutex_lock(&ls->ls_waiters_mutex);
memset(debug_buf, 0, sizeof(debug_buf));
list_for_each_entry(lkb, &ls->ls_waiters, lkb_wait_reply) {
ret = snprintf(debug_buf + pos, len - pos, "%x %d %d %s\n",
lkb->lkb_id, lkb->lkb_wait_type,
lkb->lkb_nodeid, lkb->lkb_resource->res_name);
if (ret >= len - pos)
break;
pos += ret;
}
mutex_unlock(&ls->ls_waiters_mutex);
rv = simple_read_from_buffer(userbuf, count, ppos, debug_buf, pos);
mutex_unlock(&debug_buf_lock);
return rv;
}
static const struct file_operations waiters_fops = {
.owner = THIS_MODULE,
.open = simple_open,
.read = waiters_read,
.llseek = default_llseek,
};
void dlm_delete_debug_file(struct dlm_ls *ls)
{
debugfs_remove(ls->ls_debug_rsb_dentry);
debugfs_remove(ls->ls_debug_waiters_dentry);
debugfs_remove(ls->ls_debug_locks_dentry);
debugfs_remove(ls->ls_debug_all_dentry);
debugfs_remove(ls->ls_debug_toss_dentry);
}
static int dlm_state_show(struct seq_file *file, void *offset)
{
seq_printf(file, "%s\n", dlm_midcomms_state(file->private));
return 0;
}
DEFINE_SHOW_ATTRIBUTE(dlm_state);
static int dlm_flags_show(struct seq_file *file, void *offset)
{
seq_printf(file, "%lu\n", dlm_midcomms_flags(file->private));
return 0;
}
DEFINE_SHOW_ATTRIBUTE(dlm_flags);
static int dlm_send_queue_cnt_show(struct seq_file *file, void *offset)
{
seq_printf(file, "%d\n", dlm_midcomms_send_queue_cnt(file->private));
return 0;
}
DEFINE_SHOW_ATTRIBUTE(dlm_send_queue_cnt);
static int dlm_version_show(struct seq_file *file, void *offset)
{
seq_printf(file, "0x%08x\n", dlm_midcomms_version(file->private));
return 0;
}
DEFINE_SHOW_ATTRIBUTE(dlm_version);
void *dlm_create_debug_comms_file(int nodeid, void *data)
{
struct dentry *d_node;
char name[256];
memset(name, 0, sizeof(name));
snprintf(name, 256, "%d", nodeid);
d_node = debugfs_create_dir(name, dlm_comms);
debugfs_create_file("state", 0444, d_node, data, &dlm_state_fops);
debugfs_create_file("flags", 0444, d_node, data, &dlm_flags_fops);
debugfs_create_file("send_queue_count", 0444, d_node, data,
&dlm_send_queue_cnt_fops);
debugfs_create_file("version", 0444, d_node, data, &dlm_version_fops);
return d_node;
}
void dlm_delete_debug_comms_file(void *ctx)
{
debugfs_remove(ctx);
}
void dlm_create_debug_file(struct dlm_ls *ls)
{
char name[DLM_LOCKSPACE_LEN + 8];
/* format 1 */
ls->ls_debug_rsb_dentry = debugfs_create_file(ls->ls_name,
S_IFREG | S_IRUGO,
dlm_root,
ls,
&format1_fops);
/* format 2 */
memset(name, 0, sizeof(name));
snprintf(name, DLM_LOCKSPACE_LEN + 8, "%s_locks", ls->ls_name);
ls->ls_debug_locks_dentry = debugfs_create_file(name,
S_IFREG | S_IRUGO,
dlm_root,
ls,
&format2_fops);
/* format 3 */
memset(name, 0, sizeof(name));
snprintf(name, DLM_LOCKSPACE_LEN + 8, "%s_all", ls->ls_name);
ls->ls_debug_all_dentry = debugfs_create_file(name,
S_IFREG | S_IRUGO,
dlm_root,
ls,
&format3_fops);
/* format 4 */
memset(name, 0, sizeof(name));
snprintf(name, DLM_LOCKSPACE_LEN + 8, "%s_toss", ls->ls_name);
ls->ls_debug_toss_dentry = debugfs_create_file(name,
S_IFREG | S_IRUGO,
dlm_root,
ls,
&format4_fops);
memset(name, 0, sizeof(name));
snprintf(name, DLM_LOCKSPACE_LEN + 8, "%s_waiters", ls->ls_name);
ls->ls_debug_waiters_dentry = debugfs_create_file(name,
S_IFREG | S_IRUGO,
dlm_root,
ls,
&waiters_fops);
}
void __init dlm_register_debugfs(void)
{
mutex_init(&debug_buf_lock);
dlm_root = debugfs_create_dir("dlm", NULL);
dlm_comms = debugfs_create_dir("comms", dlm_root);
}
void dlm_unregister_debugfs(void)
{
debugfs_remove(dlm_root);
}