1 files changed, 184 insertions, 0 deletions

diff --git a/fs/gfs2/locking.c b/fs/gfs2/locking.c
new file mode 100644
index 000000000000..663fee728783
--- /dev/null
+++ b/fs/gfs2/locking.c
@@ -0,0 +1,184 @@
+/*
+ * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
+ * Copyright (C) 2004-2006 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 version 2.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/wait.h>
+#include <linux/sched.h>
+#include <linux/kmod.h>
+#include <linux/fs.h>
+#include <linux/delay.h>
+#include <linux/lm_interface.h>
+
+struct lmh_wrapper {
+        struct list_head lw_list;
+        const struct lm_lockops *lw_ops;
+};
+
+/* List of registered low-level locking protocols.  A file system selects one
+   of them by name at mount time, e.g. lock_nolock, lock_dlm. */
+
+static LIST_HEAD(lmh_list);
+static DEFINE_MUTEX(lmh_lock);
+
+/**
+ * gfs2_register_lockproto - Register a low-level locking protocol
+ * @proto: the protocol definition
+ *
+ * Returns: 0 on success, -EXXX on failure
+ */
+
+int gfs2_register_lockproto(const struct lm_lockops *proto)
+{
+        struct lmh_wrapper *lw;
+
+        mutex_lock(&lmh_lock);
+
+        list_for_each_entry(lw, &lmh_list, lw_list) {
+                if (!strcmp(lw->lw_ops->lm_proto_name, proto->lm_proto_name)) {
+                        mutex_unlock(&lmh_lock);
+                        printk(KERN_INFO "GFS2: protocol %s already exists\n",
+                               proto->lm_proto_name);
+                        return -EEXIST;
+                }
+        }
+
+        lw = kzalloc(sizeof(struct lmh_wrapper), GFP_KERNEL);
+        if (!lw) {
+                mutex_unlock(&lmh_lock);
+                return -ENOMEM;
+        }
+
+        lw->lw_ops = proto;
+        list_add(&lw->lw_list, &lmh_list);
+
+        mutex_unlock(&lmh_lock);
+
+        return 0;
+}
+
+/**
+ * gfs2_unregister_lockproto - Unregister a low-level locking protocol
+ * @proto: the protocol definition
+ *
+ */
+
+void gfs2_unregister_lockproto(const struct lm_lockops *proto)
+{
+        struct lmh_wrapper *lw;
+
+        mutex_lock(&lmh_lock);
+
+        list_for_each_entry(lw, &lmh_list, lw_list) {
+                if (!strcmp(lw->lw_ops->lm_proto_name, proto->lm_proto_name)) {
+                        list_del(&lw->lw_list);
+                        mutex_unlock(&lmh_lock);
+                        kfree(lw);
+                        return;
+                }
+        }
+
+        mutex_unlock(&lmh_lock);
+
+        printk(KERN_WARNING "GFS2: can't unregister lock protocol %s\n",
+               proto->lm_proto_name);
+}
+
+/**
+ * gfs2_mount_lockproto - Mount a lock protocol
+ * @proto_name - the name of the protocol
+ * @table_name - the name of the lock space
+ * @host_data - data specific to this host
+ * @cb - the callback to the code using the lock module
+ * @sdp - The GFS2 superblock
+ * @min_lvb_size - the mininum LVB size that the caller can deal with
+ * @flags - LM_MFLAG_*
+ * @lockstruct - a structure returned describing the mount
+ *
+ * Returns: 0 on success, -EXXX on failure
+ */
+
+int gfs2_mount_lockproto(char *proto_name, char *table_name, char *host_data,
+                         lm_callback_t cb, void *cb_data,
+                         unsigned int min_lvb_size, int flags,
+                         struct lm_lockstruct *lockstruct,
+                         struct kobject *fskobj)
+{
+        struct lmh_wrapper *lw = NULL;
+        int try = 0;
+        int error, found;
+
+retry:
+        mutex_lock(&lmh_lock);
+
+        found = 0;
+        list_for_each_entry(lw, &lmh_list, lw_list) {
+                if (!strcmp(lw->lw_ops->lm_proto_name, proto_name)) {
+                        found = 1;
+                        break;
+                }
+        }
+
+        if (!found) {
+                if (!try && capable(CAP_SYS_MODULE)) {
+                        try = 1;
+                        mutex_unlock(&lmh_lock);
+                        request_module(proto_name);
+                        goto retry;
+                }
+                printk(KERN_INFO "GFS2: can't find protocol %s\n", proto_name);
+                error = -ENOENT;
+                goto out;
+        }
+
+        if (!try_module_get(lw->lw_ops->lm_owner)) {
+                try = 0;
+                mutex_unlock(&lmh_lock);
+                msleep(1000);
+                goto retry;
+        }
+
+        error = lw->lw_ops->lm_mount(table_name, host_data, cb, cb_data,
+                                     min_lvb_size, flags, lockstruct, fskobj);
+        if (error)
+                module_put(lw->lw_ops->lm_owner);
+out:
+        mutex_unlock(&lmh_lock);
+        return error;
+}
+
+void gfs2_unmount_lockproto(struct lm_lockstruct *lockstruct)
+{
+        mutex_lock(&lmh_lock);
+        lockstruct->ls_ops->lm_unmount(lockstruct->ls_lockspace);
+        if (lockstruct->ls_ops->lm_owner)
+                module_put(lockstruct->ls_ops->lm_owner);
+        mutex_unlock(&lmh_lock);
+}
+
+/**
+ * gfs2_withdraw_lockproto - abnormally unmount a lock module
+ * @lockstruct: the lockstruct passed into mount
+ *
+ */
+
+void gfs2_withdraw_lockproto(struct lm_lockstruct *lockstruct)
+{
+        mutex_lock(&lmh_lock);
+        lockstruct->ls_ops->lm_withdraw(lockstruct->ls_lockspace);
+        if (lockstruct->ls_ops->lm_owner)
+                module_put(lockstruct->ls_ops->lm_owner);
+        mutex_unlock(&lmh_lock);
+}
+
+EXPORT_SYMBOL_GPL(gfs2_register_lockproto);
+EXPORT_SYMBOL_GPL(gfs2_unregister_lockproto);
+