freebsd-dev/sys/kern/vfs_init.c

/*
 * Copyright (c) 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed
 * to Berkeley by John Heidemann of the UCLA Ficus project.
 *
 * Source: * @(#)i405_init.c 2.10 92/04/27 UCLA Ficus project
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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_init.c	8.3 (Berkeley) 1/4/94
 * $Id: vfs_init.c,v 1.34 1998/10/05 11:10:55 obrien Exp $
 */


#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/mount.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>
#include <sys/malloc.h>
#include <vm/vm_zone.h>

static void	vfs_op_init __P((void));

static void vfsinit __P((void *));
SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_FIRST, vfsinit, NULL)

MALLOC_DEFINE(M_VNODE, "vnodes", "Dynamically allocated vnodes");

/*
 * Sigh, such primitive tools are these...
 */
#if 0
#define DODEBUG(A) A
#else
#define DODEBUG(A)
#endif

static struct vfsconf void_vfsconf;

#ifdef unused
extern struct linker_set vfs_opv_descs_;
#define vfs_opv_descs ((struct vnodeopv_desc **)vfs_opv_descs_.ls_items)
#endif

extern struct vnodeop_desc *vfs_op_descs[];
				/* and the operations they perform */

/*
 * XXX this bloat just exands the sysctl__vfs linker set a little so that
 * we can attach sysctls for VFS modules without expanding the linker set.
 * Currently (1998/09/06), only one VFS uses sysctls, so 2 extra linker
 * set slots are more than sufficient.
 */
extern struct linker_set sysctl__vfs;
static int mod_xx;
SYSCTL_INT(_vfs, OID_AUTO, mod0, CTLFLAG_RD, &mod_xx, 0, "");
SYSCTL_INT(_vfs, OID_AUTO, mod1, CTLFLAG_RD, &mod_xx, 0, "");

/*
 * Zone for namei
 */
struct vm_zone *namei_zone;

/*
 * vfs_init.c
 *
 * Allocate and fill in operations vectors.
 *
 * An undocumented feature of this approach to defining operations is that
 * there can be multiple entries in vfs_opv_descs for the same operations
 * vector. This allows third parties to extend the set of operations
 * supported by another layer in a binary compatibile way. For example,
 * assume that NFS needed to be modified to support Ficus. NFS has an entry
 * (probably nfs_vnopdeop_decls) declaring all the operations NFS supports by
 * default. Ficus could add another entry (ficus_nfs_vnodeop_decl_entensions)
 * listing those new operations Ficus adds to NFS, all without modifying the
 * NFS code. (Of couse, the OTW NFS protocol still needs to be munged, but
 * that is a(whole)nother story.) This is a feature.
 *
 * Without an explicit reserve area, however, you must replace vnode_if.c
 * and vnode_if.h when you do this, or you will be derefrencing of the
 * end of vfs_op_descs[].  This is a flaw in the use of a structure
 * pointer array rather than an agregate to define vfs_op_descs.  So
 * it's not a very dynamic "feature".
 */
void
vfs_opv_init(struct vnodeopv_desc *opv)
{
	int j, k;
	vop_t ***opv_desc_vector_p;
	vop_t **opv_desc_vector;
	struct vnodeopv_entry_desc *opve_descp;

	/*
	 * Allocate the dynamic vectors and fill them in.
	 */
	opv_desc_vector_p = opv->opv_desc_vector_p;
	/*
	 * Allocate and init the vector, if it needs it.
	 * Also handle backwards compatibility.
	 */
	if (*opv_desc_vector_p == NULL) {
		/* XXX - shouldn't be M_VNODE */
		MALLOC(*opv_desc_vector_p, vop_t **,
		       vfs_opv_numops * sizeof(vop_t *), M_VNODE,
		       M_WAITOK);
		bzero(*opv_desc_vector_p,
		      vfs_opv_numops * sizeof(vop_t *));
		DODEBUG(printf("vector at %x allocated\n",
		    opv_desc_vector_p));
	}
	opv_desc_vector = *opv_desc_vector_p;
	for (j = 0; opv->opv_desc_ops[j].opve_op; j++) {
		opve_descp = &(opv->opv_desc_ops[j]);

		/*
		 * Sanity check:  is this operation listed
		 * in the list of operations?  We check this
		 * by seeing if its offest is zero.  Since
		 * the default routine should always be listed
		 * first, it should be the only one with a zero
		 * offset.  Any other operation with a zero
		 * offset is probably not listed in
		 * vfs_op_descs, and so is probably an error.
		 *
		 * A panic here means the layer programmer
		 * has committed the all-too common bug
		 * of adding a new operation to the layer's
		 * list of vnode operations but
		 * not adding the operation to the system-wide
		 * list of supported operations.
		 */
		if (opve_descp->opve_op->vdesc_offset == 0 &&
			    opve_descp->opve_op->vdesc_offset !=
				VOFFSET(vop_default)) {
			printf("operation %s not listed in %s.\n",
			    opve_descp->opve_op->vdesc_name,
			    "vfs_op_descs");
			panic ("vfs_opv_init: bad operation");
		}
		/*
		 * Fill in this entry.
		 */
		opv_desc_vector[opve_descp->opve_op->vdesc_offset] =
				opve_descp->opve_impl;
	}
	/*
	 * Finally, go back and replace unfilled routines
	 * with their default.  (Sigh, an O(n^3) algorithm.  I
	 * could make it better, but that'd be work, and n is small.)
	 */
	opv_desc_vector = *(opv->opv_desc_vector_p);
	/*
	 * Force every operations vector to have a default routine.
	 */
	if (opv_desc_vector[VOFFSET(vop_default)]==NULL) {
		panic("vfs_opv_init: operation vector without default routine.");
	}
	for (k = 0; k<vfs_opv_numops; k++)
		if (opv_desc_vector[k] == NULL)
			opv_desc_vector[k] =
				opv_desc_vector[VOFFSET(vop_default)];
}

/*
 * Initialize known vnode operations vectors.
 */
static void
vfs_op_init()
{
	int i;

	DODEBUG(printf("Vnode_interface_init.\n"));
	DODEBUG(printf ("vfs_opv_numops=%d\n", vfs_opv_numops));
#ifdef unused
	/*
	 * Set all vnode vectors to a well known value.
	 */
	for (i = 0; vfs_opv_descs[i]; i++)
		*(vfs_opv_descs[i]->opv_desc_vector_p) = NULL;
#endif
	/*
	 * assign each op to its offset
	 *
	 * XXX This should not be needed, but is because the per
	 * XXX FS ops tables are not sorted according to the
	 * XXX vnodeop_desc's offset in vfs_op_descs.  This
	 * XXX is the same reason we have to take the hit for
	 * XXX the static inline function calls instead of using
	 * XXX simple macro references.
	 */
	for (i = 0; i < vfs_opv_numops; i++)
		vfs_op_descs[i]->vdesc_offset = i;
#ifdef unused
	/* Finish the job */
	for (i = 0; vfs_opv_descs[i]; i++)
		vfs_opv_init(vfs_opv_descs[i]);
#endif
}

/*
 * Routines having to do with the management of the vnode table.
 */
extern struct vnodeops dead_vnodeops;
extern struct vnodeops spec_vnodeops;
struct vattr va_null;

/*
 * Initialize the vnode structures and initialize each file system type.
 */
/* ARGSUSED*/
static void
vfsinit(dummy)
	void *dummy;
{
	struct vfsconf **vfc, *vfsp;
	int maxtypenum;

	namei_zone = zinit("NAMEI", MAXPATHLEN, 0, 0, 2);

	/*
	 * Initialize the vnode table
	 */
	vntblinit();
	/*
	 * Initialize the vnode name cache
	 */
	nchinit();
	/*
	 * Build vnode operation vectors.
	 */
	vfs_op_init();
	/*
	 * Initialize each file system type.
	 * Vfs type numbers must be distinct from VFS_GENERIC (and VFS_VFSCONF).
	 */
	vattr_null(&va_null);
	maxvfsconf = VFS_GENERIC + 1;
}

int
vfs_register(vfc)
	struct vfsconf *vfc;
{
	struct linker_set *l;
	struct sysctl_oid **oidpp;
	struct vfsconf *vfsp;
	int error, i, maxtypenum, exists;

	vfsp = NULL;
	exists = 0;
	l = &sysctl__vfs;
	if (vfsconf)
		for (vfsp = vfsconf; vfsp->vfc_next; vfsp = vfsp->vfc_next)
			if (!strcmp(vfc->vfc_name, vfsp->vfc_name))
				return EEXIST;

	vfc->vfc_typenum = maxvfsconf++;
	if (vfc->vfc_vfsops->vfs_oid != NULL) {
		oidpp = (struct sysctl_oid **)l->ls_items;
		for (i = l->ls_length; i-- && !exists; oidpp++)
			if (*oidpp == vfc->vfc_vfsops->vfs_oid)
				exists = 1;
	}
	if (exists == 0 && vfc->vfc_vfsops->vfs_oid != NULL) {
		oidpp = (struct sysctl_oid **)l->ls_items;
		for (i = l->ls_length; i--; oidpp++) {
			if (*oidpp == NULL ||
			    *oidpp == &sysctl___vfs_mod0 ||
			    *oidpp == &sysctl___vfs_mod1) {
				*oidpp = vfc->vfc_vfsops->vfs_oid;
				(*oidpp)->oid_number = vfc->vfc_typenum;
				sysctl_order_all();
				break;
			}
		}
	}
	if (vfsp)
		vfsp->vfc_next = vfc;
	else
		vfsconf = vfc;
	vfc->vfc_next = NULL;

	/*
	 * Call init function for this VFS...
	 */
	(*(vfc->vfc_vfsops->vfs_init))(vfc);

	return 0;
}


/*
 * To be called at SI_SUB_VFS, SECOND, for each VFS before any are registered.
 */
void
vfs_mod_opv_init(handle)
	void *handle;
{
	int i;
	struct vnodeopv_desc *opv;

	opv = (struct vnodeopv_desc *)handle;
	*(opv->opv_desc_vector_p) = NULL;
	vfs_opv_init(opv);
}

int
vfs_unregister(vfc)
	struct vfsconf *vfc;
{
	struct linker_set *l;
	struct sysctl_oid **oidpp;
	struct vfsconf *vfsp, *prev_vfsp;
	int error, i, maxtypenum;

	i = vfc->vfc_typenum;

	prev_vfsp = NULL;
	for (vfsp = vfsconf; vfsp;
			prev_vfsp = vfsp, vfsp = vfsp->vfc_next) {
		if (!strcmp(vfc->vfc_name, vfsp->vfc_name))
			break;
	}
	if (vfsp == NULL)
		return EINVAL;
	if (vfsp->vfc_refcount)
		return EBUSY;
	if (vfc->vfc_vfsops->vfs_uninit != NULL) {
		error = (*vfc->vfc_vfsops->vfs_uninit)(vfsp);
		if (error)
			return (error);
	}
	if (prev_vfsp)
		prev_vfsp->vfc_next = vfsp->vfc_next;
	else
		vfsconf = vfsp->vfc_next;
	if (vfsp->vfc_vfsops->vfs_oid != NULL) {
		l = &sysctl__vfs;
		for (i = l->ls_length,
		    oidpp = (struct sysctl_oid **)l->ls_items;
		    i--; oidpp++) {
			if (*oidpp == vfsp->vfc_vfsops->vfs_oid) {
				*oidpp = NULL;
				sysctl_order_all();
				break;
			}
		}
	}
	maxtypenum = VFS_GENERIC;
	for (vfsp = vfsconf; vfsp != NULL; vfsp = vfsp->vfc_next)
		if (maxtypenum < vfsp->vfc_typenum)
			maxtypenum = vfsp->vfc_typenum;
	maxvfsconf = maxtypenum + 1;
	return 0;
}