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vfs_hooks.c
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vfs_hooks.c
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/* $NetBSD: vfs_hooks.c,v 1.6 2009/03/15 17:14:40 cegger Exp $ */
/*-
* Copyright (c) 2005 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Julio M. Merino Vidal.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* VFS hooks.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_hooks.c,v 1.6 2009/03/15 17:14:40 cegger Exp $");
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/mount.h>
#include <sys/mutex.h>
LIST_HEAD(vfs_hooks_head, vfs_hooks) vfs_hooks_head =
LIST_HEAD_INITIALIZER(vfs_hooks_head);
kmutex_t vfs_hooks_lock;
void
vfs_hooks_init(void)
{
mutex_init(&vfs_hooks_lock, MUTEX_DEFAULT, IPL_NONE);
}
int
vfs_hooks_attach(struct vfs_hooks *vfs_hooks)
{
mutex_enter(&vfs_hooks_lock);
LIST_INSERT_HEAD(&vfs_hooks_head, vfs_hooks, vfs_hooks_list);
mutex_exit(&vfs_hooks_lock);
return (0);
}
int
vfs_hooks_detach(struct vfs_hooks *vfs_hooks)
{
struct vfs_hooks *hp;
int ret = 0;
mutex_enter(&vfs_hooks_lock);
LIST_FOREACH(hp, &vfs_hooks_head, vfs_hooks_list) {
if (hp == vfs_hooks) {
LIST_REMOVE(hp, vfs_hooks_list);
break;
}
}
if (hp == NULL)
ret = ESRCH;
mutex_exit(&vfs_hooks_lock);
return (ret);
}
/*
* Macro to be used in one of the vfs_hooks_* function for hooks that
* return an error code. Calls will stop as soon as one of the hooks
* fails.
*/
#define VFS_HOOKS_W_ERROR(func, fargs, hook, hargs) \
int \
func fargs \
{ \
int error; \
struct vfs_hooks *hp; \
\
error = EJUSTRETURN; \
\
mutex_enter(&vfs_hooks_lock); \
LIST_FOREACH(hp, &vfs_hooks_head, vfs_hooks_list) { \
if (hp-> hook != NULL) { \
error = hp-> hook hargs; \
if (error != 0) \
break; \
} \
} \
mutex_exit(&vfs_hooks_lock); \
\
return error; \
}
/*
* Macro to be used in one of the vfs_hooks_* function for hooks that
* do not return any error code. All hooks will be executed
* unconditionally.
*/
#define VFS_HOOKS_WO_ERROR(func, fargs, hook, hargs) \
void \
func fargs \
{ \
struct vfs_hooks *hp; \
\
mutex_enter(&vfs_hooks_lock); \
LIST_FOREACH(hp, &vfs_hooks_head, vfs_hooks_list) { \
if (hp-> hook != NULL) \
hp-> hook hargs; \
} \
mutex_exit(&vfs_hooks_lock); \
}
/*
* Routines to iterate over VFS hooks lists and execute them.
*/
VFS_HOOKS_WO_ERROR(vfs_hooks_unmount, (struct mount *mp), vh_unmount, (mp));
VFS_HOOKS_W_ERROR(vfs_hooks_reexport, (struct mount *mp, const char *path, void *data), vh_reexport, (mp, path, data));