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freebsd-skq/sys/kern/vfs_init.c

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/*
* 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.
* 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
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#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>
MALLOC_DEFINE(M_VNODE, "vnodes", "Dynamically allocated vnodes");
/*
* The highest defined VFS number.
*/
int maxvfsconf = VFS_GENERIC + 1;
/*
* Single-linked list of configured VFSes.
* New entries are added/deleted by vfs_register()/vfs_unregister()
*/
struct vfsconf *vfsconf;
/*
* 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.
*/
/* Table of known vnodeop vectors (list of VFS vnode vectors) */
static const struct vnodeopv_desc **vnodeopv_descs;
static int vnodeopv_num;
/* Table of known descs (list of vnode op handlers "vop_access_desc") */
static struct vnodeop_desc **vfs_op_descs;
/* Reference counts for vfs_op_descs */
static int *vfs_op_desc_refs;
/* Number of descriptions */
static int num_op_descs;
/* Number of entries in each description */
static int vfs_opv_numops = 64;
/* Allow this number to be tuned at boot */
TUNABLE_INT("vfs.opv_numops", &vfs_opv_numops);
SYSCTL_INT(_vfs, OID_AUTO, opv_numops, CTLFLAG_RDTUN, &vfs_opv_numops,
0, "Maximum number of operations in vop_t vector");
static int int_cmp(const void *a, const void *b);
static int
int_cmp(const void *a, const void *b)
{
return(*(const int *)a - *(const int *)b);
}
/*
* Recalculate the operations vector/description (those parts of it that can
* be recalculated, that is.)
* Always allocate operations vector large enough to hold vfs_opv_numops
* entries. The vector is never freed or deallocated once it is initialized,
* so that vnodes might safely reference it through their v_op pointer without
* vector changing suddenly from under them.
*/
static void
vfs_opv_recalc(void)
{
int i, j, k;
int *vfs_op_offsets;
vop_t ***opv_desc_vector_p;
vop_t **opv_desc_vector;
struct vnodeopv_entry_desc *opve_descp;
const struct vnodeopv_desc *opv;
if (vfs_op_descs == NULL)
panic("vfs_opv_recalc called with null vfs_op_descs");
/*
* Allocate and initialize temporary array to store
* offsets. Sort it to put all uninitialized entries
* first and to make holes in existing offset sequence
* detectable.
*/
MALLOC(vfs_op_offsets, int *,
num_op_descs * sizeof(int), M_TEMP, M_WAITOK);
if (vfs_op_offsets == NULL)
panic("vfs_opv_recalc: no memory");
for (i = 0; i < num_op_descs; i++)
vfs_op_offsets[i] = vfs_op_descs[i]->vdesc_offset;
qsort(vfs_op_offsets, num_op_descs, sizeof(int), int_cmp);
/*
* Run through and make sure all known descs have an offset.
* Use vfs_op_offsets to locate holes in offset sequence and
* reuse them.
* vop_default_desc is hardwired at offset 1, and offset 0
* is a panic sanity check.
*/
j = 1; k = 1;
for (i = 0; i < num_op_descs; i++) {
if (vfs_op_descs[i]->vdesc_offset != 0)
continue;
/*
* Look at two adjacent entries vfs_op_offsets[j - 1] and
* vfs_op_offsets[j] and see if we can fit a new offset
* number in between. If not, look at the next pair until
* hole is found or the end of the vfs_op_offsets vector is
* reached. j has been initialized to 1 above so that
* referencing (j-1)-th element is safe and the loop will
* never execute if num_op_descs is 1. For each new value s
* of i the j loop pick up from where previous iteration has
* left off. When the last hole has been consumed or if no
* hole has been found, we will start allocating new numbers
* starting from the biggest already available offset + 1.
*/
for (; j < num_op_descs; j++) {
if (vfs_op_offsets[j - 1] < k && vfs_op_offsets[j] > k)
break;
k = vfs_op_offsets[j] + 1;
}
vfs_op_descs[i]->vdesc_offset = k++;
}
FREE(vfs_op_offsets, M_TEMP);
/* Panic if new vops will cause vector overflow */
if (k > vfs_opv_numops)
panic("VFS: Ran out of vop_t vector entries. %d entries required, only %d available.\n", k, vfs_opv_numops);
/*
* Allocate and fill in the vectors
*/
for (i = 0; i < vnodeopv_num; i++) {
opv = vnodeopv_descs[i];
opv_desc_vector_p = opv->opv_desc_vector_p;
if (*opv_desc_vector_p == NULL)
MALLOC(*opv_desc_vector_p, vop_t **,
vfs_opv_numops * sizeof(vop_t *), M_VNODE,
M_WAITOK | M_ZERO);
/* Fill in, with slot 0 being to return EOPNOTSUPP */
opv_desc_vector = *opv_desc_vector_p;
opv_desc_vector[0] = (vop_t *)vop_eopnotsupp;
for (j = 0; opv->opv_desc_ops[j].opve_op; j++) {
opve_descp = &(opv->opv_desc_ops[j]);
opv_desc_vector[opve_descp->opve_op->vdesc_offset] =
opve_descp->opve_impl;
}
/* Replace unfilled routines with their default (slot 1). */
opv_desc_vector = *(opv->opv_desc_vector_p);
if (opv_desc_vector[1] == NULL)
panic("vfs_opv_recalc: vector without a default.");
for (j = 0; j < vfs_opv_numops; j++)
if (opv_desc_vector[j] == NULL)
opv_desc_vector[j] = opv_desc_vector[1];
}
}
/* Add a set of vnode operations (a description) to the table above. */
void
vfs_add_vnodeops(const void *data)
{
const struct vnodeopv_desc *opv;
const struct vnodeopv_desc **newopv;
struct vnodeop_desc **newop;
int *newref;
struct vnodeop_desc *desc;
int i, j;
opv = (const struct vnodeopv_desc *)data;
MALLOC(newopv, const struct vnodeopv_desc **,
(vnodeopv_num + 1) * sizeof(*newopv), M_VNODE, M_WAITOK);
if (vnodeopv_descs) {
bcopy(vnodeopv_descs, newopv, vnodeopv_num * sizeof(*newopv));
FREE(vnodeopv_descs, M_VNODE);
}
newopv[vnodeopv_num] = opv;
vnodeopv_descs = newopv;
vnodeopv_num++;
/* See if we have turned up a new vnode op desc */
for (i = 0; (desc = opv->opv_desc_ops[i].opve_op); i++) {
for (j = 0; j < num_op_descs; j++) {
if (desc == vfs_op_descs[j]) {
/* found it, increase reference count */
vfs_op_desc_refs[j]++;
break;
}
}
if (j == num_op_descs) {
/* not found, new entry */
MALLOC(newop, struct vnodeop_desc **,
(num_op_descs + 1) * sizeof(*newop),
M_VNODE, M_WAITOK);
/* new reference count (for unload) */
MALLOC(newref, int *,
(num_op_descs + 1) * sizeof(*newref),
M_VNODE, M_WAITOK);
if (vfs_op_descs) {
bcopy(vfs_op_descs, newop,
num_op_descs * sizeof(*newop));
FREE(vfs_op_descs, M_VNODE);
}
if (vfs_op_desc_refs) {
bcopy(vfs_op_desc_refs, newref,
num_op_descs * sizeof(*newref));
FREE(vfs_op_desc_refs, M_VNODE);
}
newop[num_op_descs] = desc;
newref[num_op_descs] = 1;
vfs_op_descs = newop;
vfs_op_desc_refs = newref;
num_op_descs++;
}
}
vfs_opv_recalc();
}
/* Remove a vnode type from the vnode description table above. */
void
vfs_rm_vnodeops(const void *data)
{
const struct vnodeopv_desc *opv;
const struct vnodeopv_desc **newopv;
struct vnodeop_desc **newop;
int *newref;
vop_t **opv_desc_vector;
struct vnodeop_desc *desc;
int i, j, k;
opv = (const struct vnodeopv_desc *)data;
/* Lower ref counts on descs in the table and release if zero */
for (i = 0; (desc = opv->opv_desc_ops[i].opve_op); i++) {
for (j = 0; j < num_op_descs; j++) {
if (desc == vfs_op_descs[j]) {
/* found it, decrease reference count */
vfs_op_desc_refs[j]--;
break;
}
}
for (j = 0; j < num_op_descs; j++) {
if (vfs_op_desc_refs[j] > 0)
continue;
if (vfs_op_desc_refs[j] < 0)
panic("vfs_remove_vnodeops: negative refcnt");
/* Entry is going away - replace it with defaultop */
for (k = 0; k < vnodeopv_num; k++) {
opv_desc_vector =
*(vnodeopv_descs[k]->opv_desc_vector_p);
if (opv_desc_vector != NULL)
opv_desc_vector[desc->vdesc_offset] =
opv_desc_vector[1];
}
MALLOC(newop, struct vnodeop_desc **,
(num_op_descs - 1) * sizeof(*newop),
M_VNODE, M_WAITOK);
/* new reference count (for unload) */
MALLOC(newref, int *,
(num_op_descs - 1) * sizeof(*newref),
M_VNODE, M_WAITOK);
for (k = j; k < (num_op_descs - 1); k++) {
vfs_op_descs[k] = vfs_op_descs[k + 1];
vfs_op_desc_refs[k] = vfs_op_desc_refs[k + 1];
}
bcopy(vfs_op_descs, newop,
(num_op_descs - 1) * sizeof(*newop));
bcopy(vfs_op_desc_refs, newref,
(num_op_descs - 1) * sizeof(*newref));
FREE(vfs_op_descs, M_VNODE);
FREE(vfs_op_desc_refs, M_VNODE);
vfs_op_descs = newop;
vfs_op_desc_refs = newref;
num_op_descs--;
}
}
for (i = 0; i < vnodeopv_num; i++) {
if (vnodeopv_descs[i] == opv) {
for (j = i; j < (vnodeopv_num - 1); j++)
vnodeopv_descs[j] = vnodeopv_descs[j + 1];
break;
}
}
if (i == vnodeopv_num)
panic("vfs_remove_vnodeops: opv not found");
opv_desc_vector = *(opv->opv_desc_vector_p);
if (opv_desc_vector != NULL)
FREE(opv_desc_vector, M_VNODE);
MALLOC(newopv, const struct vnodeopv_desc **,
(vnodeopv_num - 1) * sizeof(*newopv), M_VNODE, M_WAITOK);
bcopy(vnodeopv_descs, newopv, (vnodeopv_num - 1) * sizeof(*newopv));
FREE(vnodeopv_descs, M_VNODE);
vnodeopv_descs = newopv;
vnodeopv_num--;
vfs_opv_recalc();
}
/*
* Routines having to do with the management of the vnode table.
*/
struct vattr va_null;
/*
* Initialize the vnode structures and initialize each filesystem type.
*/
/* ARGSUSED*/
static void
vfsinit(void *dummy)
{
vattr_null(&va_null);
}
SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_FIRST, vfsinit, NULL)
/* Register a new filesystem type in the global table */
int
vfs_register(struct vfsconf *vfc)
{
struct sysctl_oid *oidp;
struct vfsconf *vfsp;
struct vfsops *vfsops;
vfsp = NULL;
if (vfsconf)
for (vfsp = vfsconf; vfsp->vfc_next; vfsp = vfsp->vfc_next)
if (strcmp(vfc->vfc_name, vfsp->vfc_name) == 0)
return EEXIST;
vfc->vfc_typenum = maxvfsconf++;
if (vfsp)
vfsp->vfc_next = vfc;
else
vfsconf = vfc;
vfc->vfc_next = NULL;
/*
* If this filesystem has a sysctl node under vfs
* (i.e. vfs.xxfs), then change the oid number of that node to
* match the filesystem's type number. This allows user code
* which uses the type number to read sysctl variables defined
* by the filesystem to continue working. Since the oids are
* in a sorted list, we need to make sure the order is
* preserved by re-registering the oid after modifying its
* number.
*/
SLIST_FOREACH(oidp, &sysctl__vfs_children, oid_link)
if (strcmp(oidp->oid_name, vfc->vfc_name) == 0) {
sysctl_unregister_oid(oidp);
oidp->oid_number = vfc->vfc_typenum;
sysctl_register_oid(oidp);
}
/*
* Initialise unused ``struct vfsops'' fields, to use
* the vfs_std*() functions. Note, we need the mount
* and unmount operations, at the least. The check
* for vfsops available is just a debugging aid.
*/
KASSERT(vfc->vfc_vfsops != NULL,
("Filesystem %s has no vfsops", vfc->vfc_name));
/*
* Check the mount and unmount operations.
*/
vfsops = vfc->vfc_vfsops;
KASSERT(vfsops->vfs_mount != NULL || vfsops->vfs_nmount != NULL,
("Filesystem %s has no (n)mount op", vfc->vfc_name));
KASSERT(vfsops->vfs_unmount != NULL,
("Filesystem %s has no unmount op", vfc->vfc_name));
if (vfsops->vfs_start == NULL)
/* make a file system operational */
vfsops->vfs_start = vfs_stdstart;
if (vfsops->vfs_root == NULL)
/* return file system's root vnode */
vfsops->vfs_root = vfs_stdroot;
if (vfsops->vfs_quotactl == NULL)
/* quota control */
vfsops->vfs_quotactl = vfs_stdquotactl;
if (vfsops->vfs_statfs == NULL)
/* return file system's status */
vfsops->vfs_statfs = vfs_stdstatfs;
if (vfsops->vfs_sync == NULL)
/*
* flush unwritten data (nosync)
* file systems can use vfs_stdsync
* explicitly by setting it in the
* vfsop vector.
*/
vfsops->vfs_sync = vfs_stdnosync;
if (vfsops->vfs_vget == NULL)
/* convert an inode number to a vnode */
vfsops->vfs_vget = vfs_stdvget;
if (vfsops->vfs_fhtovp == NULL)
/* turn an NFS file handle into a vnode */
vfsops->vfs_fhtovp = vfs_stdfhtovp;
if (vfsops->vfs_checkexp == NULL)
/* check if file system is exported */
vfsops->vfs_checkexp = vfs_stdcheckexp;
if (vfsops->vfs_vptofh == NULL)
/* turn a vnode into an NFS file handle */
vfsops->vfs_vptofh = vfs_stdvptofh;
if (vfsops->vfs_init == NULL)
/* file system specific initialisation */
vfsops->vfs_init = vfs_stdinit;
if (vfsops->vfs_uninit == NULL)
/* file system specific uninitialisation */
vfsops->vfs_uninit = vfs_stduninit;
if (vfsops->vfs_extattrctl == NULL)
/* extended attribute control */
vfsops->vfs_extattrctl = vfs_stdextattrctl;
if (vfsops->vfs_sysctl == NULL)
vfsops->vfs_sysctl = vfs_stdsysctl;
/*
* Call init function for this VFS...
*/
(*(vfc->vfc_vfsops->vfs_init))(vfc);
return 0;
}
/* Remove registration of a filesystem type */
int
vfs_unregister(struct vfsconf *vfc)
{
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;
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;
}
/*
* Standard kernel module handling code for filesystem modules.
* Referenced from VFS_SET().
*/
int
vfs_modevent(module_t mod, int type, void *data)
{
struct vfsconf *vfc;
int error = 0;
vfc = (struct vfsconf *)data;
switch (type) {
case MOD_LOAD:
if (vfc)
error = vfs_register(vfc);
break;
case MOD_UNLOAD:
if (vfc)
error = vfs_unregister(vfc);
break;
default: /* including MOD_SHUTDOWN */
break;
}
return (error);
}
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