1 /* $NetBSD: vfs_hooks.c,v 1.6 2009/03/15 17:14:40 cegger Exp $ */ 2 3 /*- 4 * Copyright (c) 2005 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Julio M. Merino Vidal. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /* 33 * VFS hooks. 34 */ 35 36 #include <sys/cdefs.h> 37 __KERNEL_RCSID(0, "$NetBSD: vfs_hooks.c,v 1.6 2009/03/15 17:14:40 cegger Exp $"); 38 39 #include <sys/param.h> 40 #include <sys/queue.h> 41 #include <sys/mount.h> 42 #include <sys/mutex.h> 43 44 LIST_HEAD(vfs_hooks_head, vfs_hooks) vfs_hooks_head = 45 LIST_HEAD_INITIALIZER(vfs_hooks_head); 46 47 kmutex_t vfs_hooks_lock; 48 49 void 50 vfs_hooks_init(void) 51 { 52 53 mutex_init(&vfs_hooks_lock, MUTEX_DEFAULT, IPL_NONE); 54 } 55 56 int 57 vfs_hooks_attach(struct vfs_hooks *vfs_hooks) 58 { 59 60 mutex_enter(&vfs_hooks_lock); 61 LIST_INSERT_HEAD(&vfs_hooks_head, vfs_hooks, vfs_hooks_list); 62 mutex_exit(&vfs_hooks_lock); 63 64 return (0); 65 } 66 67 int 68 vfs_hooks_detach(struct vfs_hooks *vfs_hooks) 69 { 70 struct vfs_hooks *hp; 71 int ret = 0; 72 73 mutex_enter(&vfs_hooks_lock); 74 LIST_FOREACH(hp, &vfs_hooks_head, vfs_hooks_list) { 75 if (hp == vfs_hooks) { 76 LIST_REMOVE(hp, vfs_hooks_list); 77 break; 78 } 79 } 80 if (hp == NULL) 81 ret = ESRCH; 82 mutex_exit(&vfs_hooks_lock); 83 84 return (ret); 85 } 86 87 /* 88 * Macro to be used in one of the vfs_hooks_* function for hooks that 89 * return an error code. Calls will stop as soon as one of the hooks 90 * fails. 91 */ 92 #define VFS_HOOKS_W_ERROR(func, fargs, hook, hargs) \ 93 int \ 94 func fargs \ 95 { \ 96 int error; \ 97 struct vfs_hooks *hp; \ 98 \ 99 error = EJUSTRETURN; \ 100 \ 101 mutex_enter(&vfs_hooks_lock); \ 102 LIST_FOREACH(hp, &vfs_hooks_head, vfs_hooks_list) { \ 103 if (hp-> hook != NULL) { \ 104 error = hp-> hook hargs; \ 105 if (error != 0) \ 106 break; \ 107 } \ 108 } \ 109 mutex_exit(&vfs_hooks_lock); \ 110 \ 111 return error; \ 112 } 113 114 /* 115 * Macro to be used in one of the vfs_hooks_* function for hooks that 116 * do not return any error code. All hooks will be executed 117 * unconditionally. 118 */ 119 #define VFS_HOOKS_WO_ERROR(func, fargs, hook, hargs) \ 120 void \ 121 func fargs \ 122 { \ 123 struct vfs_hooks *hp; \ 124 \ 125 mutex_enter(&vfs_hooks_lock); \ 126 LIST_FOREACH(hp, &vfs_hooks_head, vfs_hooks_list) { \ 127 if (hp-> hook != NULL) \ 128 hp-> hook hargs; \ 129 } \ 130 mutex_exit(&vfs_hooks_lock); \ 131 } 132 133 /* 134 * Routines to iterate over VFS hooks lists and execute them. 135 */ 136 137 VFS_HOOKS_WO_ERROR(vfs_hooks_unmount, (struct mount *mp), vh_unmount, (mp)); 138 VFS_HOOKS_W_ERROR(vfs_hooks_reexport, (struct mount *mp, const char *path, void *data), vh_reexport, (mp, path, data)); 139