[PATCH 15/18] ocfs2: Break out stackglue into modules.

From: Joel Becker
Date: Wed Mar 05 2008 - 19:34:54 EST

We define the ocfs2_stack_plugin structure to represent a stack driver.
The o2cb stack code is split into stack_o2cb.c. This becomes the
ocfs2_stack_o2cb.ko module.

The stackglue generic functions are similarly split into the
ocfs2_stackglue.ko module. This module now provides an interface to
register drivers. The ocfs2_stack_o2cb driver registers itself. As
part of this interface, ocfs2_stackglue can load drivers on demand.
This is accomplished in ocfs2_cluster_connect().

ocfs2_cluster_disconnect() is now notified when a _hangup() is pending.
If a hangup is pending, it will not release the driver module and will
let _hangup() do that.

Signed-off-by: Joel Becker <joel.becker@xxxxxxxxxx>
---
fs/ocfs2/Makefile | 7 +-
fs/ocfs2/dlmglue.c | 7 +-
fs/ocfs2/dlmglue.h | 2 +-
fs/ocfs2/stack_o2cb.c | 41 +++++++--
fs/ocfs2/stackglue.c | 238 ++++++++++++++++++++++++++++++++++++++++++++-----
fs/ocfs2/stackglue.h | 36 +++++++-
fs/ocfs2/super.c | 16 ++--
7 files changed, 297 insertions(+), 50 deletions(-)

diff --git a/fs/ocfs2/Makefile b/fs/ocfs2/Makefile
index 8e86195..b734254 100644
--- a/fs/ocfs2/Makefile
+++ b/fs/ocfs2/Makefile
@@ -2,7 +2,7 @@ EXTRA_CFLAGS += -Ifs/ocfs2

EXTRA_CFLAGS += -DCATCH_BH_JBD_RACES

-obj-$(CONFIG_OCFS2_FS) += ocfs2.o
+obj-$(CONFIG_OCFS2_FS) += ocfs2.o ocfs2_stackglue.o ocfs2_stack_o2cb.o

ocfs2-objs := \
alloc.o \
@@ -24,8 +24,6 @@ ocfs2-objs := \
namei.o \
resize.o \
slot_map.o \
- stackglue.o \
- stack_o2cb.o \
suballoc.o \
super.o \
symlink.o \
@@ -33,5 +31,8 @@ ocfs2-objs := \
uptodate.o \
ver.o

+ocfs2_stackglue-objs := stackglue.o
+ocfs2_stack_o2cb-objs := stack_o2cb.o
+
obj-$(CONFIG_OCFS2_FS) += cluster/
obj-$(CONFIG_OCFS2_FS) += dlm/
diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 435d7e0..71af7d6 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -2641,7 +2641,7 @@ int ocfs2_dlm_init(struct ocfs2_super *osb)
mlog_errno(status);
mlog(ML_ERROR,
"could not find this host's node number\n");
- ocfs2_cluster_disconnect(conn);
+ ocfs2_cluster_disconnect(conn, 0);
goto bail;
}

@@ -2663,7 +2663,8 @@ bail:
return status;
}

-void ocfs2_dlm_shutdown(struct ocfs2_super *osb)
+void ocfs2_dlm_shutdown(struct ocfs2_super *osb,
+ int hangup_pending)
{
mlog_entry_void();

@@ -2683,7 +2684,7 @@ void ocfs2_dlm_shutdown(struct ocfs2_super *osb)
ocfs2_lock_res_free(&osb->osb_super_lockres);
ocfs2_lock_res_free(&osb->osb_rename_lockres);

- ocfs2_cluster_disconnect(osb->cconn);
+ ocfs2_cluster_disconnect(osb->cconn, hangup_pending);
osb->cconn = NULL;

ocfs2_dlm_shutdown_debug(osb);
diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
index 34b7598..2bb01f0 100644
--- a/fs/ocfs2/dlmglue.h
+++ b/fs/ocfs2/dlmglue.h
@@ -58,7 +58,7 @@ struct ocfs2_meta_lvb {
#define OCFS2_LOCK_NONBLOCK (0x04)

int ocfs2_dlm_init(struct ocfs2_super *osb);
-void ocfs2_dlm_shutdown(struct ocfs2_super *osb);
+void ocfs2_dlm_shutdown(struct ocfs2_super *osb, int hangup_pending);
void ocfs2_lock_res_init_once(struct ocfs2_lock_res *res);
void ocfs2_inode_lock_res_init(struct ocfs2_lock_res *res,
enum ocfs2_lock_type type,
diff --git a/fs/ocfs2/stack_o2cb.c b/fs/ocfs2/stack_o2cb.c
index c9bc354..ac1d74c 100644
--- a/fs/ocfs2/stack_o2cb.c
+++ b/fs/ocfs2/stack_o2cb.c
@@ -18,7 +18,7 @@
*/

#include <linux/crc32.h>
-#include <linux/kmod.h>
+#include <linux/module.h>

/* Needed for AOP_TRUNCATED_PAGE in mlog_errno() */
#include <linux/fs.h>
@@ -33,6 +33,8 @@ struct o2dlm_private {
struct dlm_eviction_cb op_eviction_cb;
};

+static struct ocfs2_stack_plugin o2cb_stack;
+
/* These should be identical */
#if (DLM_LOCK_IV != LKM_IVMODE)
# error Lock modes do not match
@@ -158,23 +160,23 @@ static int dlm_status_to_errno(enum dlm_status status)

static void o2dlm_lock_ast_wrapper(void *astarg)
{
- BUG_ON(stack_glue_lproto == NULL);
+ BUG_ON(o2cb_stack.sp_proto == NULL);

- stack_glue_lproto->lp_lock_ast(astarg);
+ o2cb_stack.sp_proto->lp_lock_ast(astarg);
}

static void o2dlm_blocking_ast_wrapper(void *astarg, int level)
{
- BUG_ON(stack_glue_lproto == NULL);
+ BUG_ON(o2cb_stack.sp_proto == NULL);

- stack_glue_lproto->lp_blocking_ast(astarg, level);
+ o2cb_stack.sp_proto->lp_blocking_ast(astarg, level);
}

static void o2dlm_unlock_ast_wrapper(void *astarg, enum dlm_status status)
{
int error = dlm_status_to_errno(status);

- BUG_ON(stack_glue_lproto == NULL);
+ BUG_ON(o2cb_stack.sp_proto == NULL);

/*
* In o2dlm, you can get both the lock_ast() for the lock being
@@ -190,7 +192,7 @@ static void o2dlm_unlock_ast_wrapper(void *astarg, enum dlm_status status)
if (status == DLM_CANCELGRANT)
return;

- stack_glue_lproto->lp_unlock_ast(astarg, error);
+ o2cb_stack.sp_proto->lp_unlock_ast(astarg, error);
}

static int o2cb_dlm_lock(struct ocfs2_cluster_connection *conn,
@@ -267,6 +269,7 @@ static int o2cb_cluster_connect(struct ocfs2_cluster_connection *conn)
struct dlm_protocol_version dlm_version;

BUG_ON(conn == NULL);
+ BUG_ON(o2cb_stack.sp_proto == NULL);

/* for now we only have one cluster/node, make sure we see it
* in the heartbeat universe */
@@ -314,7 +317,8 @@ out:
return rc;
}

-static int o2cb_cluster_disconnect(struct ocfs2_cluster_connection *conn)
+static int o2cb_cluster_disconnect(struct ocfs2_cluster_connection *conn,
+ int hangup_pending)
{
struct dlm_ctxt *dlm = conn->cc_lockspace;
struct o2dlm_private *priv = conn->cc_private;
@@ -393,3 +397,24 @@ struct ocfs2_stack_operations o2cb_stack_ops = {
.dump_lksb = o2cb_dump_lksb,
};

+static struct ocfs2_stack_plugin o2cb_stack = {
+ .sp_name = "o2cb",
+ .sp_ops = &o2cb_stack_ops,
+ .sp_owner = THIS_MODULE,
+};
+
+static int __init o2cb_stack_init(void)
+{
+ return ocfs2_stack_glue_register(&o2cb_stack);
+}
+
+static void __exit o2cb_stack_exit(void)
+{
+ ocfs2_stack_glue_unregister(&o2cb_stack);
+}
+
+MODULE_AUTHOR("Oracle");
+MODULE_DESCRIPTION("ocfs2 driver for the classic o2cb stack");
+MODULE_LICENSE("GPL");
+module_init(o2cb_stack_init);
+module_exit(o2cb_stack_exit);
diff --git a/fs/ocfs2/stackglue.c b/fs/ocfs2/stackglue.c
index e197367..1978c9c 100644
--- a/fs/ocfs2/stackglue.c
+++ b/fs/ocfs2/stackglue.c
@@ -18,17 +18,176 @@
* General Public License for more details.
*/

+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/module.h>
#include <linux/slab.h>
#include <linux/kmod.h>

-/* Needed for AOP_TRUNCATED_PAGE in mlog_errno() */
-#include <linux/fs.h>
+#include "stackglue.h"

-#include "cluster/masklog.h"
+static struct ocfs2_locking_protocol *lproto;
+static DEFINE_SPINLOCK(ocfs2_stack_lock);
+static LIST_HEAD(ocfs2_stack_list);

-#include "stackglue.h"
+/*
+ * The stack currently in use. If not null, active_stack->sp_count > 0,
+ * the module is pinned, and the locking protocol cannot be changed.
+ */
+static struct ocfs2_stack_plugin *active_stack;
+
+static struct ocfs2_stack_plugin *ocfs2_stack_lookup(const char *name)
+{
+ struct ocfs2_stack_plugin *p;
+
+ assert_spin_locked(&ocfs2_stack_lock);
+
+ list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
+ if (!strcmp(p->sp_name, name))
+ return p;
+ }
+
+ return NULL;
+}
+
+static int ocfs2_stack_driver_request(const char *name)
+{
+ int rc;
+ struct ocfs2_stack_plugin *p;
+
+ spin_lock(&ocfs2_stack_lock);
+
+ if (active_stack) {
+ /*
+ * If the active stack isn't the one we want, it cannot
+ * be selected right now.
+ */
+ if (!strcmp(active_stack->sp_name, name))
+ rc = 0;
+ else
+ rc = -EBUSY;
+ goto out;
+ }
+
+ p = ocfs2_stack_lookup(name);
+ if (!p || !try_module_get(p->sp_owner)) {
+ rc = -ENOENT;
+ goto out;
+ }
+
+ /* Ok, the stack is pinned */
+ p->sp_count++;
+ active_stack = p;
+
+ rc = 0;
+
+out:
+ spin_unlock(&ocfs2_stack_lock);
+ return rc;
+}
+
+/*
+ * This function looks up the appropriate stack and makes it active. If
+ * there is no stack, it tries to load it. It will fail if the stack still
+ * cannot be found. It will also fail if a different stack is in use.
+ */
+static int ocfs2_stack_driver_get(const char *name)
+{
+ int rc;
+
+ rc = ocfs2_stack_driver_request(name);
+ if (rc == -ENOENT) {
+ request_module("ocfs2_stack_%s", name);
+ rc = ocfs2_stack_driver_request(name);
+ }
+
+ if (rc == -ENOENT) {
+ printk(KERN_ERR
+ "ocfs2: Cluster stack driver \"%s\" cannot be found\n",
+ name);
+ } else if (rc == -EBUSY) {
+ printk(KERN_ERR
+ "ocfs2: A different cluster stack driver is in use\n");
+ }
+
+ return rc;
+}

-struct ocfs2_locking_protocol *stack_glue_lproto;
+static void ocfs2_stack_driver_put(void)
+{
+ spin_lock(&ocfs2_stack_lock);
+ BUG_ON(active_stack == NULL);
+ BUG_ON(active_stack->sp_count == 0);
+
+ active_stack->sp_count--;
+ if (!active_stack->sp_count) {
+ module_put(active_stack->sp_owner);
+ active_stack = NULL;
+ }
+ spin_unlock(&ocfs2_stack_lock);
+}
+
+int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin)
+{
+ int rc;
+
+ spin_lock(&ocfs2_stack_lock);
+ if (!ocfs2_stack_lookup(plugin->sp_name)) {
+ plugin->sp_count = 0;
+ plugin->sp_proto = lproto;
+ list_add(&plugin->sp_list, &ocfs2_stack_list);
+ printk(KERN_INFO "ocfs2: Registered cluster interface %s\n",
+ plugin->sp_name);
+ rc = 0;
+ } else {
+ printk(KERN_ERR "ocfs2: Stack \"%s\" already registered\n",
+ plugin->sp_name);
+ rc = -EEXIST;
+ }
+ spin_unlock(&ocfs2_stack_lock);
+
+ return rc;
+}
+EXPORT_SYMBOL_GPL(ocfs2_stack_glue_register);
+
+void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin)
+{
+ struct ocfs2_stack_plugin *p;
+
+ spin_lock(&ocfs2_stack_lock);
+ p = ocfs2_stack_lookup(plugin->sp_name);
+ if (p) {
+ BUG_ON(p != plugin);
+ BUG_ON(plugin == active_stack);
+ BUG_ON(plugin->sp_count != 0);
+ list_del_init(&plugin->sp_list);
+ printk(KERN_INFO "ocfs2: Unregistered cluster interface %s\n",
+ plugin->sp_name);
+ } else {
+ printk(KERN_ERR "Stack \"%s\" is not registered\n",
+ plugin->sp_name);
+ }
+ spin_unlock(&ocfs2_stack_lock);
+}
+EXPORT_SYMBOL_GPL(ocfs2_stack_glue_unregister);
+
+void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto)
+{
+ struct ocfs2_stack_plugin *p;
+
+ BUG_ON(proto == NULL);
+
+ spin_lock(&ocfs2_stack_lock);
+ BUG_ON(active_stack != NULL);
+
+ lproto = proto;
+ list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
+ p->sp_proto = lproto;
+ }
+
+ spin_unlock(&ocfs2_stack_lock);
+}
+EXPORT_SYMBOL_GPL(ocfs2_stack_glue_set_locking_protocol);


int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
@@ -39,26 +198,29 @@ int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
unsigned int namelen,
void *astarg)
{
- BUG_ON(stack_glue_lproto == NULL);
+ BUG_ON(lproto == NULL);

- return o2cb_stack_ops.dlm_lock(conn, mode, lksb, flags,
- name, namelen, astarg);
+ return active_stack->sp_ops->dlm_lock(conn, mode, lksb, flags,
+ name, namelen, astarg);
}
+EXPORT_SYMBOL_GPL(ocfs2_dlm_lock);

int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
union ocfs2_dlm_lksb *lksb,
u32 flags,
void *astarg)
{
- BUG_ON(stack_glue_lproto == NULL);
+ BUG_ON(lproto == NULL);

- return o2cb_stack_ops.dlm_unlock(conn, lksb, flags, astarg);
+ return active_stack->sp_ops->dlm_unlock(conn, lksb, flags, astarg);
}
+EXPORT_SYMBOL_GPL(ocfs2_dlm_unlock);

int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb)
{
- return o2cb_stack_ops.lock_status(lksb);
+ return active_stack->sp_ops->lock_status(lksb);
}
+EXPORT_SYMBOL_GPL(ocfs2_dlm_lock_status);

/*
* Why don't we cast to ocfs2_meta_lvb? The "clean" answer is that we
@@ -67,13 +229,15 @@ int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb)
*/
void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb)
{
- return o2cb_stack_ops.lock_lvb(lksb);
+ return active_stack->sp_ops->lock_lvb(lksb);
}
+EXPORT_SYMBOL_GPL(ocfs2_dlm_lvb);

void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb)
{
- o2cb_stack_ops.dump_lksb(lksb);
+ active_stack->sp_ops->dump_lksb(lksb);
}
+EXPORT_SYMBOL_GPL(ocfs2_dlm_dump_lksb);

int ocfs2_cluster_connect(const char *group,
int grouplen,
@@ -107,11 +271,16 @@ int ocfs2_cluster_connect(const char *group,
new_conn->cc_recovery_data = recovery_data;

/* Start the new connection at our maximum compatibility level */
- new_conn->cc_version = stack_glue_lproto->lp_max_version;
+ new_conn->cc_version = lproto->lp_max_version;
+
+ /* This will pin the stack driver if successful */
+ rc = ocfs2_stack_driver_get("o2cb");
+ if (rc)
+ goto out_free;

- rc = o2cb_stack_ops.connect(new_conn);
+ rc = active_stack->sp_ops->connect(new_conn);
if (rc) {
- mlog_errno(rc);
+ ocfs2_stack_driver_put();
goto out_free;
}

@@ -124,39 +293,60 @@ out_free:
out:
return rc;
}
+EXPORT_SYMBOL_GPL(ocfs2_cluster_connect);

-int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn)
+/* If hangup_pending is 0, the stack driver will be dropped */
+int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
+ int hangup_pending)
{
int ret;

BUG_ON(conn == NULL);

- ret = o2cb_stack_ops.disconnect(conn);
+ ret = active_stack->sp_ops->disconnect(conn, hangup_pending);

/* XXX Should we free it anyway? */
- if (!ret)
+ if (!ret) {
kfree(conn);
+ if (!hangup_pending)
+ ocfs2_stack_driver_put();
+ }

return ret;
}
+EXPORT_SYMBOL_GPL(ocfs2_cluster_disconnect);

void ocfs2_cluster_hangup(const char *group, int grouplen)
{
BUG_ON(group == NULL);
BUG_ON(group[grouplen] != '\0');

- o2cb_stack_ops.hangup(group, grouplen);
+ active_stack->sp_ops->hangup(group, grouplen);
+
+ /* cluster_disconnect() was called with hangup_pending==1 */
+ ocfs2_stack_driver_put();
}
+EXPORT_SYMBOL_GPL(ocfs2_cluster_hangup);

int ocfs2_cluster_this_node(unsigned int *node)
{
- return o2cb_stack_ops.this_node(node);
+ return active_stack->sp_ops->this_node(node);
}
+EXPORT_SYMBOL_GPL(ocfs2_cluster_this_node);

-void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto)
+
+static int __init ocfs2_stack_glue_init(void)
{
- BUG_ON(proto != NULL);
+ return 0;
+}

- stack_glue_lproto = proto;
+static void __exit ocfs2_stack_glue_exit(void)
+{
+ lproto = NULL;
}

+MODULE_AUTHOR("Oracle");
+MODULE_DESCRIPTION("ocfs2 cluter stack glue layer");
+MODULE_LICENSE("GPL");
+module_init(ocfs2_stack_glue_init);
+module_exit(ocfs2_stack_glue_exit);
diff --git a/fs/ocfs2/stackglue.h b/fs/ocfs2/stackglue.h
index 0836322..c96c8bb 100644
--- a/fs/ocfs2/stackglue.h
+++ b/fs/ocfs2/stackglue.h
@@ -119,14 +119,21 @@ struct ocfs2_stack_operations {
* Once ->disconnect() has returned, the connection structure will
* be freed. Thus, a stack must not return from ->disconnect()
* until it will no longer reference the conn pointer.
+ *
+ * If hangup_pending is zero, ocfs2_cluster_disconnect() will also
+ * be dropping the reference on the module.
*/
- int (*disconnect)(struct ocfs2_cluster_connection *conn);
+ int (*disconnect)(struct ocfs2_cluster_connection *conn,
+ int hangup_pending);

/*
* ocfs2_cluster_hangup() exists for compatibility with older
* ocfs2 tools. Only the classic stack really needs it. As such
* ->hangup() is not required of all stacks. See the comment by
* ocfs2_cluster_hangup() for more details.
+ *
+ * Note that ocfs2_cluster_hangup() can only be called if
+ * hangup_pending was passed to ocfs2_cluster_disconnect().
*/
void (*hangup)(const char *group, int grouplen);

@@ -184,13 +191,32 @@ struct ocfs2_stack_operations {
void (*dump_lksb)(union ocfs2_dlm_lksb *lksb);
};

+/*
+ * Each stack plugin must describe itself by registering a
+ * ocfs2_stack_plugin structure. This is only seen by stackglue and the
+ * stack driver.
+ */
+struct ocfs2_stack_plugin {
+ char *sp_name;
+ struct ocfs2_stack_operations *sp_ops;
+ struct module *sp_owner;
+
+ /* These are managed by the stackglue code. */
+ struct list_head sp_list;
+ unsigned int sp_count;
+ struct ocfs2_locking_protocol *sp_proto;
+};
+
+
+/* Used by the filesystem */
int ocfs2_cluster_connect(const char *group,
int grouplen,
void (*recovery_handler)(int node_num,
void *recovery_data),
void *recovery_data,
struct ocfs2_cluster_connection **conn);
-int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn);
+int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
+ int hangup_pending);
void ocfs2_cluster_hangup(const char *group, int grouplen);
int ocfs2_cluster_this_node(unsigned int *node);

@@ -212,6 +238,8 @@ void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb);

void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto);

-extern struct ocfs2_locking_protocol *stack_glue_lproto;
-extern struct ocfs2_stack_operations o2cb_stack_ops;
+
+/* Used by stack plugins */
+int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin);
+void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin);
#endif /* STACKGLUE_H */
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index b4a02a0..e27a0d4 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -1186,7 +1186,7 @@ leave:

static void ocfs2_dismount_volume(struct super_block *sb, int mnt_err)
{
- int tmp;
+ int tmp, hangup_needed = 0;
struct ocfs2_super *osb = NULL;
char nodestr[8];

@@ -1225,19 +1225,21 @@ static void ocfs2_dismount_volume(struct super_block *sb, int mnt_err)

ocfs2_release_system_inodes(osb);

- if (osb->cconn)
- ocfs2_dlm_shutdown(osb);
-
- debugfs_remove(osb->osb_debug_root);
-
/*
- * This is a small hack to move ocfs2_hb_ctl into stackglue.
* If we're dismounting due to mount error, mount.ocfs2 will clean
* up heartbeat. If we're a local mount, there is no heartbeat.
* If we failed before we got a uuid_str yet, we can't stop
* heartbeat. Otherwise, do it.
*/
if (!mnt_err && !ocfs2_mount_local(osb) && osb->uuid_str)
+ hangup_needed = 1;
+
+ if (osb->cconn)
+ ocfs2_dlm_shutdown(osb, hangup_needed);
+
+ debugfs_remove(osb->osb_debug_root);
+
+ if (hangup_needed)
ocfs2_cluster_hangup(osb->uuid_str, strlen(osb->uuid_str));

atomic_set(&osb->vol_state, VOLUME_DISMOUNTED);
--
1.5.3.8

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