/* * Copyright (C) 2003 Sistina Software. * Copyright (C) 2004 Red Hat, Inc. All rights reserved. * * Module Author: Heinz Mauelshagen * * This file is released under the GPL. * * Path selector registration. */ #include "dm.h" #include "dm-path-selector.h" #include <linux/slab.h> struct ps_internal { struct path_selector_type pst; struct list_head list; long use; }; #define pst_to_psi(__pst) container_of((__pst), struct ps_internal, pst) static LIST_HEAD(_path_selectors); static DECLARE_RWSEM(_ps_lock); static struct ps_internal *__find_path_selector_type(const char *name) { struct ps_internal *psi; list_for_each_entry(psi, &_path_selectors, list) { if (!strcmp(name, psi->pst.name)) return psi; } return NULL; } static struct ps_internal *get_path_selector(const char *name) { struct ps_internal *psi; down_read(&_ps_lock); psi = __find_path_selector_type(name); if (psi) { if ((psi->use == 0) && !try_module_get(psi->pst.module)) psi = NULL; else psi->use++; } up_read(&_ps_lock); return psi; } struct path_selector_type *dm_get_path_selector(const char *name) { struct ps_internal *psi; if (!name) return NULL; psi = get_path_selector(name); if (!psi) { request_module("dm-%s", name); psi = get_path_selector(name); } return psi ? &psi->pst : NULL; } void dm_put_path_selector(struct path_selector_type *pst) { struct ps_internal *psi; if (!pst) return; down_read(&_ps_lock); psi = __find_path_selector_type(pst->name); if (!psi) goto out; if (--psi->use == 0) module_put(psi->pst.module); BUG_ON(psi->use < 0); out: up_read(&_ps_lock); } static struct ps_internal *_alloc_path_selector(struct path_selector_type *pst) { struct ps_internal *psi = kmalloc(sizeof(*psi), GFP_KERNEL); if (psi) { memset(psi, 0, sizeof(*psi)); psi->pst = *pst; } return psi; } int dm_register_path_selector(struct path_selector_type *pst) { int r = 0; struct ps_internal *psi = _alloc_path_selector(pst); if (!psi) return -ENOMEM; down_write(&_ps_lock); if (__find_path_selector_type(pst->name)) { kfree(psi); r = -EEXIST; } else list_add(&psi->list, &_path_selectors); up_write(&_ps_lock); return r; } int dm_unregister_path_selector(struct path_selector_type *pst) { struct ps_internal *psi; down_write(&_ps_lock); psi = __find_path_selector_type(pst->name); if (!psi) { up_write(&_ps_lock); return -EINVAL; } if (psi->use) { up_write(&_ps_lock); return -ETXTBSY; } list_del(&psi->list); up_write(&_ps_lock); kfree(psi); return 0; } EXPORT_SYMBOL_GPL(dm_register_path_selector); EXPORT_SYMBOL_GPL(dm_unregister_path_selector);