diff options
Diffstat (limited to 'fs/gfs2/locking.c')
| -rw-r--r-- | fs/gfs2/locking.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/fs/gfs2/locking.c b/fs/gfs2/locking.c new file mode 100644 index 0000000..663fee7 --- /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); + |