This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / fs / gfs2 / locking.c

diff --git a/fs/gfs2/locking.c b/fs/gfs2/locking.c
new file mode 100644 (file)
index 0000000..bc4abcd
--- /dev/null
+++ b/fs/gfs2/locking.c
@@ -0,0 +1,186 @@
+/*
+ * 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);
+EXPORT_SYMBOL_GPL(gfs2_withdraw_lockproto);
+EXPORT_SYMBOL_GPL(gfs2_mount_lockproto);
+EXPORT_SYMBOL_GPL(gfs2_unmount_lockproto);