[PATCH 1/6] dlm: allow multiple lockspace creates

From: David Teigland
Date: Mon Sep 22 2008 - 14:42:26 EST

Add a count for lockspace create and release so that create can
be called multiple times to use the lockspace from different places.
Also add the new flag DLM_LSFL_NEWEXCL to create a lockspace with
the previous behavior of returning -EEXIST if the lockspace already
exists.

Signed-off-by: David Teigland <teigland@xxxxxxxxxx>
---
fs/dlm/dlm_internal.h | 6 ++-
fs/dlm/lockspace.c | 107 ++++++++++++++++++++++++++++---------------
fs/dlm/user.c | 54 +++++++++++++--------
fs/dlm/user.h | 3 +-
fs/gfs2/locking/dlm/mount.c | 3 +-
include/linux/dlm.h | 5 ++-
include/linux/dlm_device.h | 2 +-
7 files changed, 116 insertions(+), 64 deletions(-)

diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index 5a7ac33..9e0622a 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -2,7 +2,7 @@
*******************************************************************************
**
** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
-** Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
+** Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
**
** This copyrighted material is made available to anyone wishing to use,
** modify, copy, or redistribute it subject to the terms and conditions
@@ -441,7 +441,9 @@ struct dlm_ls {
uint32_t ls_global_id; /* global unique lockspace ID */
uint32_t ls_exflags;
int ls_lvblen;
- int ls_count; /* reference count */
+ int ls_count; /* refcount of processes in
+ the dlm using this ls */
+ int ls_create_count; /* create/release refcount */
unsigned long ls_flags; /* LSFL_ */
struct kobject ls_kobj;

diff --git a/fs/dlm/lockspace.c b/fs/dlm/lockspace.c
index 499e167..56eae4e 100644
--- a/fs/dlm/lockspace.c
+++ b/fs/dlm/lockspace.c
@@ -2,7 +2,7 @@
*******************************************************************************
**
** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
-** Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
+** Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
**
** This copyrighted material is made available to anyone wishing to use,
** modify, copy, or redistribute it subject to the terms and conditions
@@ -23,6 +23,7 @@
#include "lock.h"
#include "recover.h"
#include "requestqueue.h"
+#include "user.h"

static int ls_count;
static struct mutex ls_lock;
@@ -246,23 +247,6 @@ static void dlm_scand_stop(void)
kthread_stop(scand_task);
}

-static struct dlm_ls *dlm_find_lockspace_name(char *name, int namelen)
-{
- struct dlm_ls *ls;
-
- spin_lock(&lslist_lock);
-
- list_for_each_entry(ls, &lslist, ls_list) {
- if (ls->ls_namelen == namelen &&
- memcmp(ls->ls_name, name, namelen) == 0)
- goto out;
- }
- ls = NULL;
- out:
- spin_unlock(&lslist_lock);
- return ls;
-}
-
struct dlm_ls *dlm_find_lockspace_global(uint32_t id)
{
struct dlm_ls *ls;
@@ -327,6 +311,7 @@ static void remove_lockspace(struct dlm_ls *ls)
for (;;) {
spin_lock(&lslist_lock);
if (ls->ls_count == 0) {
+ WARN_ON(ls->ls_create_count != 0);
list_del(&ls->ls_list);
spin_unlock(&lslist_lock);
return;
@@ -381,7 +366,7 @@ static int new_lockspace(char *name, int namelen, void **lockspace,
uint32_t flags, int lvblen)
{
struct dlm_ls *ls;
- int i, size, error = -ENOMEM;
+ int i, size, error;
int do_unreg = 0;

if (namelen > DLM_LOCKSPACE_LEN)
@@ -393,12 +378,32 @@ static int new_lockspace(char *name, int namelen, void **lockspace,
if (!try_module_get(THIS_MODULE))
return -EINVAL;

- ls = dlm_find_lockspace_name(name, namelen);
- if (ls) {
- *lockspace = ls;
+ error = 0;
+
+ spin_lock(&lslist_lock);
+ list_for_each_entry(ls, &lslist, ls_list) {
+ WARN_ON(ls->ls_create_count <= 0);
+ if (ls->ls_namelen != namelen)
+ continue;
+ if (memcmp(ls->ls_name, name, namelen))
+ continue;
+ if (flags & DLM_LSFL_NEWEXCL) {
+ error = -EEXIST;
+ break;
+ }
+ ls->ls_create_count++;
module_put(THIS_MODULE);
- return -EEXIST;
+ error = 1; /* not an error, return 0 */
+ break;
}
+ spin_unlock(&lslist_lock);
+
+ if (error < 0)
+ goto out;
+ if (error)
+ goto ret_zero;
+
+ error = -ENOMEM;

ls = kzalloc(sizeof(struct dlm_ls) + namelen, GFP_KERNEL);
if (!ls)
@@ -418,8 +423,9 @@ static int new_lockspace(char *name, int namelen, void **lockspace,
ls->ls_allocation = GFP_KERNEL;

/* ls_exflags are forced to match among nodes, and we don't
- need to require all nodes to have TIMEWARN or FS set */
- ls->ls_exflags = (flags & ~(DLM_LSFL_TIMEWARN | DLM_LSFL_FS));
+ need to require all nodes to have some flags set */
+ ls->ls_exflags = (flags & ~(DLM_LSFL_TIMEWARN | DLM_LSFL_FS |
+ DLM_LSFL_NEWEXCL));

size = dlm_config.ci_rsbtbl_size;
ls->ls_rsbtbl_size = size;
@@ -510,6 +516,7 @@ static int new_lockspace(char *name, int namelen, void **lockspace,
down_write(&ls->ls_in_recovery);

spin_lock(&lslist_lock);
+ ls->ls_create_count = 1;
list_add(&ls->ls_list, &lslist);
spin_unlock(&lslist_lock);

@@ -548,7 +555,7 @@ static int new_lockspace(char *name, int namelen, void **lockspace,
dlm_create_debug_file(ls);

log_debug(ls, "join complete");
-
+ ret_zero:
*lockspace = ls;
return 0;

@@ -635,11 +642,32 @@ static int release_lockspace(struct dlm_ls *ls, int force)
struct dlm_lkb *lkb;
struct dlm_rsb *rsb;
struct list_head *head;
- int i;
- int busy = lockspace_busy(ls);
+ int i, busy, rv;
+
+ busy = lockspace_busy(ls);
+
+ spin_lock(&lslist_lock);
+ if (ls->ls_create_count == 1) {
+ if (busy > force)
+ rv = -EBUSY;
+ else {
+ /* remove_lockspace takes ls off lslist */
+ ls->ls_create_count = 0;
+ rv = 0;
+ }
+ } else if (ls->ls_create_count > 1) {
+ rv = --ls->ls_create_count;
+ } else {
+ rv = -EINVAL;
+ }
+ spin_unlock(&lslist_lock);
+
+ if (rv) {
+ log_debug(ls, "release_lockspace no remove %d", rv);
+ return rv;
+ }

- if (busy > force)
- return -EBUSY;
+ dlm_device_deregister(ls);

if (force < 3)
do_uevent(ls, 0);
@@ -720,15 +748,10 @@ static int release_lockspace(struct dlm_ls *ls, int force)
dlm_clear_members(ls);
dlm_clear_members_gone(ls);
kfree(ls->ls_node_array);
+ log_debug(ls, "release_lockspace final free");
kobject_put(&ls->ls_kobj);
/* The ls structure will be freed when the kobject is done with */

- mutex_lock(&ls_lock);
- ls_count--;
- if (!ls_count)
- threads_stop();
- mutex_unlock(&ls_lock);
-
module_put(THIS_MODULE);
return 0;
}
@@ -750,11 +773,21 @@ static int release_lockspace(struct dlm_ls *ls, int force)
int dlm_release_lockspace(void *lockspace, int force)
{
struct dlm_ls *ls;
+ int error;

ls = dlm_find_lockspace_local(lockspace);
if (!ls)
return -EINVAL;
dlm_put_lockspace(ls);
- return release_lockspace(ls, force);
+
+ mutex_lock(&ls_lock);
+ error = release_lockspace(ls, force);
+ if (!error)
+ ls_count--;
+ else if (!ls_count)
+ threads_stop();
+ mutex_unlock(&ls_lock);
+
+ return error;
}

diff --git a/fs/dlm/user.c b/fs/dlm/user.c
index 34f14a1..6542110 100644
--- a/fs/dlm/user.c
+++ b/fs/dlm/user.c
@@ -1,5 +1,5 @@
/*
- * Copyright (C) 2006-2007 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2006-2008 Red Hat, Inc. All rights reserved.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
@@ -340,10 +340,15 @@ static int device_user_deadlock(struct dlm_user_proc *proc,
return error;
}

-static int create_misc_device(struct dlm_ls *ls, char *name)
+static int dlm_device_register(struct dlm_ls *ls, char *name)
{
int error, len;

+ /* The device is already registered. This happens when the
+ lockspace is created multiple times from userspace. */
+ if (ls->ls_device.name)
+ return 0;
+
error = -ENOMEM;
len = strlen(name) + strlen(name_prefix) + 2;
ls->ls_device.name = kzalloc(len, GFP_KERNEL);
@@ -363,6 +368,22 @@ fail:
return error;
}

+int dlm_device_deregister(struct dlm_ls *ls)
+{
+ int error;
+
+ /* The device is not registered. This happens when the lockspace
+ was never used from userspace, or when device_create_lockspace()
+ calls dlm_release_lockspace() after the register fails. */
+ if (!ls->ls_device.name)
+ return 0;
+
+ error = misc_deregister(&ls->ls_device);
+ if (!error)
+ kfree(ls->ls_device.name);
+ return error;
+}
+
static int device_user_purge(struct dlm_user_proc *proc,
struct dlm_purge_params *params)
{
@@ -397,7 +418,7 @@ static int device_create_lockspace(struct dlm_lspace_params *params)
if (!ls)
return -ENOENT;

- error = create_misc_device(ls, params->name);
+ error = dlm_device_register(ls, params->name);
dlm_put_lockspace(ls);

if (error)
@@ -421,31 +442,22 @@ static int device_remove_lockspace(struct dlm_lspace_params *params)
if (!ls)
return -ENOENT;

- /* Deregister the misc device first, so we don't have
- * a device that's not attached to a lockspace. If
- * dlm_release_lockspace fails then we can recreate it
- */
- error = misc_deregister(&ls->ls_device);
- if (error) {
- dlm_put_lockspace(ls);
- goto out;
- }
- kfree(ls->ls_device.name);
-
if (params->flags & DLM_USER_LSFLG_FORCEFREE)
force = 2;

lockspace = ls->ls_local_handle;
+ dlm_put_lockspace(ls);

- /* dlm_release_lockspace waits for references to go to zero,
- so all processes will need to close their device for the ls
- before the release will procede */
+ /* The final dlm_release_lockspace waits for references to go to
+ zero, so all processes will need to close their device for the
+ ls before the release will proceed. release also calls the
+ device_deregister above. Converting a positive return value
+ from release to zero means that userspace won't know when its
+ release was the final one, but it shouldn't need to know. */

- dlm_put_lockspace(ls);
error = dlm_release_lockspace(lockspace, force);
- if (error)
- create_misc_device(ls, ls->ls_name);
- out:
+ if (error > 0)
+ error = 0;
return error;
}

diff --git a/fs/dlm/user.h b/fs/dlm/user.h
index d38e9f3..c528b6b 100644
--- a/fs/dlm/user.h
+++ b/fs/dlm/user.h
@@ -1,5 +1,5 @@
/*
- * Copyright (C) 2006 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2006-2008 Red Hat, Inc. All rights reserved.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
@@ -12,5 +12,6 @@
void dlm_user_add_ast(struct dlm_lkb *lkb, int type);
int dlm_user_init(void);
void dlm_user_exit(void);
+int dlm_device_deregister(struct dlm_ls *ls);

#endif
diff --git a/fs/gfs2/locking/dlm/mount.c b/fs/gfs2/locking/dlm/mount.c
index 09d78c2..0c4cbe6 100644
--- a/fs/gfs2/locking/dlm/mount.c
+++ b/fs/gfs2/locking/dlm/mount.c
@@ -144,7 +144,8 @@ static int gdlm_mount(char *table_name, char *host_data,

error = dlm_new_lockspace(ls->fsname, strlen(ls->fsname),
&ls->dlm_lockspace,
- DLM_LSFL_FS | (nodir ? DLM_LSFL_NODIR : 0),
+ DLM_LSFL_FS | DLM_LSFL_NEWEXCL |
+ (nodir ? DLM_LSFL_NODIR : 0),
GDLM_LVB_SIZE);
if (error) {
log_error("dlm_new_lockspace error %d", error);
diff --git a/include/linux/dlm.h b/include/linux/dlm.h
index 203a025..b9cd386 100644
--- a/include/linux/dlm.h
+++ b/include/linux/dlm.h
@@ -2,7 +2,7 @@
*******************************************************************************
**
** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
-** Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
+** Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
**
** This copyrighted material is made available to anyone wishing to use,
** modify, copy, or redistribute it subject to the terms and conditions
@@ -65,9 +65,12 @@ struct dlm_lksb {
char * sb_lvbptr;
};

+/* dlm_new_lockspace() flags */
+
#define DLM_LSFL_NODIR 0x00000001
#define DLM_LSFL_TIMEWARN 0x00000002
#define DLM_LSFL_FS 0x00000004
+#define DLM_LSFL_NEWEXCL 0x00000008

#ifdef __KERNEL__

diff --git a/include/linux/dlm_device.h b/include/linux/dlm_device.h
index c603450..3060783 100644
--- a/include/linux/dlm_device.h
+++ b/include/linux/dlm_device.h
@@ -26,7 +26,7 @@
/* Version of the device interface */
#define DLM_DEVICE_VERSION_MAJOR 6
#define DLM_DEVICE_VERSION_MINOR 0
-#define DLM_DEVICE_VERSION_PATCH 0
+#define DLM_DEVICE_VERSION_PATCH 1

/* struct passed to the lock write */
struct dlm_lock_params {
--
1.5.5.1

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