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vfs_hooks.c revision 1.3 
      1 /*	$NetBSD: vfs_hooks.c,v 1.3 2008/04/28 20:24:05 martin 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 1.3 2008/04/28 20:24:05 martin Exp $");
     38 
     39 #include <sys/param.h>
     40 #include <sys/mount.h>
     41 
     42 /*
     43  * Static list of file system specific hook sets supported by the kernel.
     44  */
     45 __link_set_decl(vfs_hooks, struct vfs_hooks);
     46 
     47 /*
     48  * Initialize a VFS hook set that does nothing.  This is to ensure that
     49  * we have, at the very least, one item in the link set.  Otherwise,
     50  * ld(1) will complain.
     51  */
     52 static struct vfs_hooks null_hooks = {
     53 	NULL		/* vh_unmount */
     54 };
     55 VFS_HOOKS_ATTACH(null_hooks);
     56 
     57 /*
     58  * Macro to be used in one of the vfs_hooks_* function for hooks that
     59  * return an error code.  Calls will stop as soon as one of the hooks
     60  * fails.
     61  */
     62 #define VFS_HOOKS_W_ERROR(func, args)					\
     63 	int error;							\
     64 	struct vfs_hooks * const *hp;					\
     65  									\
     66 	error = 0;							\
     67  									\
     68 	__link_set_foreach(hp, vfs_hooks) {				\
     69 		if ((*hp)-> func != NULL) {				\
     70 			error = (*hp)-> func args;			\
     71 			if (error != 0)					\
     72 				break;					\
     73 		}							\
     74 	}								\
     75  									\
     76 	return error;
     77 
     78 /*
     79  * Macro to be used in one of the vfs_hooks_* function for hooks that
     80  * do not return any error code.  All hooks will be executed
     81  * unconditionally.
     82  */
     83 #define VFS_HOOKS_WO_ERROR(func, fargs, hook, hargs)			\
     84 void									\
     85 func fargs								\
     86 {									\
     87 	struct vfs_hooks * const *hp;					\
     88  									\
     89 	__link_set_foreach(hp, vfs_hooks) {				\
     90 		if ((*hp)-> hook != NULL)				\
     91 			(*hp)-> hook hargs;				\
     92 	}								\
     93 }
     94 
     95 /*
     96  * Routines to iterate over VFS hooks lists and execute them.
     97  */
     98 
     99 VFS_HOOKS_WO_ERROR(vfs_hooks_unmount, (struct mount *mp), vh_unmount, (mp));
    100 
    101 /*
    102 void
    103 vfs_hooks_unmount(struct mount *mp)
    104 {
    105 
    106 	VFS_HOOKS_WO_ERROR(vh_unmount, (mp));
    107 }
    108 */
    109