xnu-517.tar.gz

[apple/xnu.git] / bsd / vfs / vfs_init.c

/*
 * Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
/*
 * 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	8.5 (Berkeley) 5/11/95
 */


#include <sys/param.h>
#include <sys/mount.h>
#include <sys/time.h>
#include <sys/vm.h>
#include <sys/vnode.h>
#include <sys/stat.h>
#include <sys/namei.h>
#include <sys/ucred.h>
#include <sys/buf.h>
#include <sys/errno.h>
#include <sys/malloc.h>


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

extern uid_t console_user;
extern struct vnodeopv_desc *vfs_opv_descs[];
				/* a list of lists of vnodeops defns */
extern struct vnodeop_desc *vfs_op_descs[];
				/* and the operations they perform */
/*
 * This code doesn't work if the defn is **vnodop_defns with cc.
 * The problem is because of the compiler sometimes putting in an
 * extra level of indirection for arrays.  It's an interesting
 * "feature" of C.
 */
int vfs_opv_numops;

typedef (*PFI)();   /* the standard Pointer to a Function returning an Int */

/*
 * A miscellaneous routine.
 * A generic "default" routine that just returns an error.
 */
int
vn_default_error()
{

	return (EOPNOTSUPP);
}

/*
 * 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.
 */
void
vfs_opv_init()
{
	int i, j, k;
	int (***opv_desc_vector_p)(void *);
	int (**opv_desc_vector)(void *);
	struct vnodeopv_entry_desc *opve_descp;

	/*
	 * Allocate the dynamic vectors and fill them in.
	 */
	for (i=0; vfs_opv_descs[i]; i++) {
		opv_desc_vector_p = vfs_opv_descs[i]->opv_desc_vector_p;
		/*
		 * Allocate and init the vector, if it needs it.
		 * Also handle backwards compatibility.
		 */
		if (*opv_desc_vector_p == NULL) {
			MALLOC(*opv_desc_vector_p, PFI*,
			       vfs_opv_numops*sizeof(PFI), M_TEMP, M_WAITOK);
			bzero (*opv_desc_vector_p, vfs_opv_numops*sizeof(PFI));
			DODEBUG(printf("vector at %x allocated\n",
			    opv_desc_vector_p));
		}
		opv_desc_vector = *opv_desc_vector_p;
		for (j=0; vfs_opv_descs[i]->opv_desc_ops[j].opve_op; j++) {
			opve_descp = &(vfs_opv_descs[i]->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.)
	 */
	for (i = 0; vfs_opv_descs[i]; i++) {
		opv_desc_vector = *(vfs_opv_descs[i]->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.
 */
void
vfs_op_init()
{
	int i;

	DODEBUG(printf("Vnode_interface_init.\n"));
	/*
	 * 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;
	/*
	 * Figure out how many ops there are by counting the table,
	 * and assign each its offset.
	 */
	for (vfs_opv_numops = 0, i = 0; vfs_op_descs[i]; i++) {
		vfs_op_descs[i]->vdesc_offset = vfs_opv_numops;
		vfs_opv_numops++;
	}
	DODEBUG(printf ("vfs_opv_numops=%d\n", vfs_opv_numops));
}

/*
 * 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.
 */
vfsinit()
{
	struct vfsconf *vfsp;
	int i, maxtypenum;

	/*
	 * Initialize the "console user" for access purposes:
	 */
	console_user = (uid_t)0;
	
	/*
	 * Initialize the vnode table
	 */
	vntblinit();
	/*
	 * Initialize the filesystem event mechanism.
	 */
	vfs_event_init();
	/*
	 * Initialize the vnode name cache
	 */
	nchinit();
	/*
	 * Build vnode operation vectors.
	 */
	vfs_op_init();
	vfs_opv_init();   /* finish the job */
	/*
	 * Initialize each file system type in the static list,
	 * until the first NULL ->vfs_vfsops is encountered.
	 */
	vattr_null(&va_null);
	numused_vfsslots = maxtypenum = 0;
	for (vfsp = vfsconf, i = 0; i < maxvfsconf; i++, vfsp++) {
		if (vfsp->vfc_vfsops == (struct	vfsops *)0)
			break;
		if (i) vfsconf[i-1].vfc_next = vfsp;
		if (maxtypenum <= vfsp->vfc_typenum)
			maxtypenum = vfsp->vfc_typenum + 1;
		(*vfsp->vfc_vfsops->vfs_init)(vfsp);
		numused_vfsslots++;
	}
	/* next vfc_typenum to be used */
	maxvfsconf = maxtypenum;
}

/*
 * Name:	vfsconf_add
 *
 * Description:	Add a filesystem to the vfsconf list at the first
 *		unused slot.  If no slots are available, return an
 *		error.
 *
 * Parameter:	nvfsp		vfsconf for VFS to add
 *
 * Returns:	0		Success
 *		-1		Failure
 *
 * Notes:	The vfsconf should be treated as a linked list by
 *		all external references, as the implementation is
 *		expected to change in the future.  The linkage is
 *		through ->vfc_next, and the list is NULL terminated.
 *
 * Warning:	This code assumes that vfsconf[0] is non-empty.
 */
int
vfsconf_add(struct vfsconf *nvfsp)
{
	int slot;
	struct vfsconf *slotp;

	if (nvfsp == NULL)	/* overkill */
		return (-1);
	
	/*
	 * Find the next empty slot; we recognize an empty slot by a
	 * NULL-valued ->vfc_vfsops, so if we delete a VFS, we must
	 * ensure we set the entry back to NULL.
	 */
	for (slot = 0; slot < maxvfsslots; slot++) {
		if (vfsconf[slot].vfc_vfsops == NULL)
			break;
	}
	if (slot == maxvfsslots) {
		/* out of static slots; allocate one instead */
		MALLOC(slotp, struct vfsconf *, sizeof(struct vfsconf),
							M_TEMP, M_WAITOK);
	} else {
		slotp = &vfsconf[slot];
	}

	/*
	 * Replace the contents of the next empty slot with the contents
	 * of the provided nvfsp.
	 *
	 * Note; Takes advantage of the fact that 'slot' was left
	 * with the value of 'maxvfslots' in the allocation case.
	 */
	bcopy(nvfsp, slotp, sizeof(struct vfsconf));
	if (slot != 0) {
		slotp->vfc_next = vfsconf[slot - 1].vfc_next;
		vfsconf[slot - 1].vfc_next = slotp;
	} else {
		slotp->vfc_next = NULL;
	}
	numused_vfsslots++;

	/*
	 * Call through the ->vfs_init(); use slotp instead of nvfsp,
	 * so that if the FS cares where it's instance record is, it
	 * can find it later.
	 *
	 * XXX All code that calls ->vfs_init treats it as if it
	 * XXX returns a "void', and can never fail.
	 */
	if (nvfsp->vfc_vfsops->vfs_init)
		(*nvfsp->vfc_vfsops->vfs_init)(slotp);

	return(0);
}

/*
 * Name:	vfsconf_del
 *
 * Description:	Remove a filesystem from the vfsconf list by name.
 *		If no such filesystem exists, return an error.
 *
 * Parameter:	fs_name		name of VFS to remove
 *
 * Returns:	0		Success
 *		-1		Failure
 *
 * Notes:	Hopefully all filesystems have unique names.
 */
int
vfsconf_del(char * fs_name)
{
	struct vfsconf **vcpp;
	struct vfsconf *vcdelp;

	/*
	 * Traverse the list looking for fs_name; if found, *vcpp
	 * will contain the address of the pointer to the entry to
	 * be removed.
	 */
	for( vcpp = &vfsconf; *vcpp; vcpp = &(*vcpp)->vfc_next) {
		if (strcmp( (*vcpp)->vfc_name, fs_name) == 0)
            break;
        }

	if (*vcpp == NULL) {
	   /* XXX need real error code for entry not found */
	   return(-1);
	}

	/* Unlink entry */
	vcdelp = *vcpp;
	*vcpp = (*vcpp)->vfc_next;

	/*
	 * Is this an entry from our static table?  We find out by
	 * seeing if the pointer to the object to be deleted places
	 * the object in the address space containing the table (or not).
	 */
	if (vcdelp >= vfsconf && vcdelp < (vfsconf + maxvfsslots)) {	/* Y */
		/* Mark as empty for vfscon_add() */
		bzero(vcdelp, sizeof(struct vfsconf));
		numused_vfsslots--;
	} else {							/* N */
		/*
		 * This entry was dynamically allocated; we must free it;
		 * we would prefer to have just linked the caller's
		 * vfsconf onto our list, but it may not be persistent
		 * because of the previous (copying) implementation.
		 */
		 FREE(vcdelp, M_TEMP);
	}

	return(0);
}