The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_init.c

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    1 /*
    2  * Copyright (c) 1989, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * This code is derived from software contributed
    6  * to Berkeley by John Heidemann of the UCLA Ficus project.
    7  *
    8  * Source: * @(#)i405_init.c 2.10 92/04/27 UCLA Ficus project
    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  * 3. All advertising materials mentioning features or use of this software
   19  *    must display the following acknowledgement:
   20  *      This product includes software developed by the University of
   21  *      California, Berkeley and its contributors.
   22  * 4. Neither the name of the University nor the names of its contributors
   23  *    may be used to endorse or promote products derived from this software
   24  *    without specific prior written permission.
   25  *
   26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   36  * SUCH DAMAGE.
   37  *
   38  *      @(#)vfs_init.c  8.3 (Berkeley) 1/4/94
   39  * $FreeBSD$
   40  */
   41 
   42 
   43 #include <sys/param.h>
   44 #include <sys/systm.h>
   45 #include <sys/kernel.h>
   46 #include <sys/mount.h>
   47 #include <sys/sysctl.h>
   48 #include <sys/vnode.h>
   49 #include <sys/malloc.h>
   50 #include <vm/vm_zone.h>
   51 
   52 
   53 MALLOC_DEFINE(M_VNODE, "vnodes", "Dynamically allocated vnodes");
   54 
   55 /*
   56  * Zone for namei
   57  */
   58 struct vm_zone *namei_zone;
   59 
   60 /*
   61  * vfs_init() will set maxvfsconf
   62  * to the highest defined type number.
   63  */
   64 int maxvfsconf;
   65 struct vfsconf *vfsconf;
   66 
   67 /*
   68  * vfs_init.c
   69  *
   70  * Allocate and fill in operations vectors.
   71  *
   72  * An undocumented feature of this approach to defining operations is that
   73  * there can be multiple entries in vfs_opv_descs for the same operations
   74  * vector. This allows third parties to extend the set of operations
   75  * supported by another layer in a binary compatibile way. For example,
   76  * assume that NFS needed to be modified to support Ficus. NFS has an entry
   77  * (probably nfs_vnopdeop_decls) declaring all the operations NFS supports by
   78  * default. Ficus could add another entry (ficus_nfs_vnodeop_decl_entensions)
   79  * listing those new operations Ficus adds to NFS, all without modifying the
   80  * NFS code. (Of couse, the OTW NFS protocol still needs to be munged, but
   81  * that is a(whole)nother story.) This is a feature.
   82  */
   83 
   84 /* Table of known vnodeop vectors (list of VFS vnode vectors) */
   85 static const struct vnodeopv_desc **vnodeopv_descs;
   86 static int vnodeopv_num;
   87 
   88 /* Table of known descs (list of vnode op handlers "vop_access_desc") */
   89 static struct vnodeop_desc **vfs_op_descs;
   90 static int *vfs_op_desc_refs;                   /* reference counts */
   91 static int num_op_descs;
   92 static int vfs_opv_numops;
   93 
   94 static void
   95 vfs_opv_recalc(void)
   96 {
   97         int i, j;
   98         vop_t ***opv_desc_vector_p;
   99         vop_t **opv_desc_vector;
  100         struct vnodeopv_entry_desc *opve_descp;
  101         const struct vnodeopv_desc *opv;
  102 
  103         if (vfs_op_descs == NULL)
  104                 panic("vfs_opv_recalc called with null vfs_op_descs");
  105 
  106         /*
  107          * Run through and make sure all known descs have an offset
  108          *
  109          * vop_default_desc is hardwired at offset 1, and offset 0
  110          * is a panic sanity check.
  111          */
  112         vfs_opv_numops = 0;
  113         for (i = 0; i < num_op_descs; i++)
  114                 if (vfs_opv_numops < (vfs_op_descs[i]->vdesc_offset + 1))
  115                         vfs_opv_numops = vfs_op_descs[i]->vdesc_offset + 1;
  116         for (i = 0; i < num_op_descs; i++)
  117                 if (vfs_op_descs[i]->vdesc_offset == 0)
  118                         vfs_op_descs[i]->vdesc_offset = vfs_opv_numops++;
  119         /*
  120          * Allocate and fill in the vectors
  121          */
  122         for (i = 0; i < vnodeopv_num; i++) {
  123                 opv = vnodeopv_descs[i];
  124                 opv_desc_vector_p = opv->opv_desc_vector_p;
  125                 if (*opv_desc_vector_p)
  126                         FREE(*opv_desc_vector_p, M_VNODE);
  127                 MALLOC(*opv_desc_vector_p, vop_t **,
  128                        vfs_opv_numops * sizeof(vop_t *), M_VNODE, M_WAITOK);
  129                 if (*opv_desc_vector_p == NULL)
  130                         panic("no memory for vop_t ** vector");
  131                 bzero(*opv_desc_vector_p, vfs_opv_numops * sizeof(vop_t *));
  132 
  133                 /* Fill in, with slot 0 being panic */
  134                 opv_desc_vector = *opv_desc_vector_p;
  135                 opv_desc_vector[0] = (vop_t *)vop_panic;
  136                 for (j = 0; opv->opv_desc_ops[j].opve_op; j++) {
  137                         opve_descp = &(opv->opv_desc_ops[j]);
  138                         opv_desc_vector[opve_descp->opve_op->vdesc_offset] =
  139                                 opve_descp->opve_impl;
  140                 }
  141 
  142                 /* Replace unfilled routines with their default (slot 1). */
  143                 opv_desc_vector = *(opv->opv_desc_vector_p);
  144                 if (opv_desc_vector[1] == NULL)
  145                         panic("vfs_opv_recalc: vector without a default.");
  146                 for (j = 0; j < vfs_opv_numops; j++)
  147                         if (opv_desc_vector[j] == NULL)
  148                                 opv_desc_vector[j] = opv_desc_vector[1];
  149         }
  150 }
  151 
  152 void
  153 vfs_add_vnodeops(const void *data)
  154 {
  155         const struct vnodeopv_desc *opv;
  156         const struct vnodeopv_desc **newopv;
  157         struct vnodeop_desc **newop;
  158         int *newref;
  159         vop_t **opv_desc_vector;
  160         struct vnodeop_desc *desc;
  161         int i, j;
  162 
  163         opv = (const struct vnodeopv_desc *)data;
  164         MALLOC(newopv, const struct vnodeopv_desc **,
  165                (vnodeopv_num + 1) * sizeof(*newopv), M_VNODE, M_WAITOK);
  166         if (newopv == NULL)
  167                 panic("vfs_add_vnodeops: no memory");
  168         if (vnodeopv_descs) {
  169                 bcopy(vnodeopv_descs, newopv, vnodeopv_num * sizeof(*newopv));
  170                 FREE(vnodeopv_descs, M_VNODE);
  171         }
  172         newopv[vnodeopv_num] = opv;
  173         vnodeopv_descs = newopv;
  174         vnodeopv_num++;
  175 
  176         /* See if we have turned up a new vnode op desc */
  177         opv_desc_vector = *(opv->opv_desc_vector_p);
  178         for (i = 0; (desc = opv->opv_desc_ops[i].opve_op); i++) {
  179                 for (j = 0; j < num_op_descs; j++) {
  180                         if (desc == vfs_op_descs[j]) {
  181                                 /* found it, increase reference count */
  182                                 vfs_op_desc_refs[j]++;
  183                                 break;
  184                         }
  185                 }
  186                 if (j == num_op_descs) {
  187                         /* not found, new entry */
  188                         MALLOC(newop, struct vnodeop_desc **,
  189                                (num_op_descs + 1) * sizeof(*newop),
  190                                M_VNODE, M_WAITOK);
  191                         if (newop == NULL)
  192                                 panic("vfs_add_vnodeops: no memory for desc");
  193                         /* new reference count (for unload) */
  194                         MALLOC(newref, int *,
  195                                 (num_op_descs + 1) * sizeof(*newref),
  196                                 M_VNODE, M_WAITOK);
  197                         if (newref == NULL)
  198                                 panic("vfs_add_vnodeops: no memory for refs");
  199                         if (vfs_op_descs) {
  200                                 bcopy(vfs_op_descs, newop,
  201                                         num_op_descs * sizeof(*newop));
  202                                 FREE(vfs_op_descs, M_VNODE);
  203                         }
  204                         if (vfs_op_desc_refs) {
  205                                 bcopy(vfs_op_desc_refs, newref,
  206                                         num_op_descs * sizeof(*newref));
  207                                 FREE(vfs_op_desc_refs, M_VNODE);
  208                         }
  209                         newop[num_op_descs] = desc;
  210                         newref[num_op_descs] = 1;
  211                         vfs_op_descs = newop;
  212                         vfs_op_desc_refs = newref;
  213                         num_op_descs++;
  214                 }
  215         }
  216         vfs_opv_recalc();
  217 }
  218 
  219 void
  220 vfs_rm_vnodeops(const void *data)
  221 {
  222         const struct vnodeopv_desc *opv;
  223         const struct vnodeopv_desc **newopv;
  224         struct vnodeop_desc **newop;
  225         int *newref;
  226         vop_t **opv_desc_vector;
  227         struct vnodeop_desc *desc;
  228         int i, j, k;
  229 
  230         opv = (const struct vnodeopv_desc *)data;
  231         /* Lower ref counts on descs in the table and release if zero */
  232         opv_desc_vector = *(opv->opv_desc_vector_p);
  233         for (i = 0; (desc = opv->opv_desc_ops[i].opve_op); i++) {
  234                 for (j = 0; j < num_op_descs; j++) {
  235                         if (desc == vfs_op_descs[j]) {
  236                                 /* found it, decrease reference count */
  237                                 vfs_op_desc_refs[j]--;
  238                                 break;
  239                         }
  240                 }
  241                 for (j = 0; j < num_op_descs; j++) {
  242                         if (vfs_op_desc_refs[j] > 0)
  243                                 continue;
  244                         if (vfs_op_desc_refs[j] < 0)
  245                                 panic("vfs_remove_vnodeops: negative refcnt");
  246                         MALLOC(newop, struct vnodeop_desc **,
  247                                (num_op_descs - 1) * sizeof(*newop),
  248                                M_VNODE, M_WAITOK);
  249                         if (newop == NULL)
  250                                 panic("vfs_remove_vnodeops: no memory for desc");
  251                         /* new reference count (for unload) */
  252                         MALLOC(newref, int *,
  253                                 (num_op_descs - 1) * sizeof(*newref),
  254                                 M_VNODE, M_WAITOK);
  255                         if (newref == NULL)
  256                                 panic("vfs_remove_vnodeops: no memory for refs");
  257                         for (k = j; k < (num_op_descs - 1); k++) {
  258                                 vfs_op_descs[k] = vfs_op_descs[k + 1];
  259                                 vfs_op_desc_refs[k] = vfs_op_desc_refs[k + 1];
  260                         }
  261                         bcopy(vfs_op_descs, newop,
  262                                 (num_op_descs - 1) * sizeof(*newop));
  263                         bcopy(vfs_op_desc_refs, newref,
  264                                 (num_op_descs - 1) * sizeof(*newref));
  265                         FREE(vfs_op_descs, M_VNODE);
  266                         FREE(vfs_op_desc_refs, M_VNODE);
  267                         vfs_op_descs = newop;
  268                         vfs_op_desc_refs = newref;
  269                         num_op_descs--;
  270                 }
  271         }
  272 
  273         for (i = 0; i < vnodeopv_num; i++) {
  274                 if (vnodeopv_descs[i] == opv) {
  275                         for (j = i; j < (vnodeopv_num - 1); j++)
  276                                 vnodeopv_descs[j] = vnodeopv_descs[j + 1];
  277                         break;
  278                 }
  279         }
  280         if (i == vnodeopv_num)
  281                 panic("vfs_remove_vnodeops: opv not found");
  282         MALLOC(newopv, const struct vnodeopv_desc **,
  283                (vnodeopv_num - 1) * sizeof(*newopv), M_VNODE, M_WAITOK);
  284         if (newopv == NULL)
  285                 panic("vfs_remove_vnodeops: no memory");
  286         bcopy(vnodeopv_descs, newopv, (vnodeopv_num - 1) * sizeof(*newopv));
  287         FREE(vnodeopv_descs, M_VNODE);
  288         vnodeopv_descs = newopv;
  289         vnodeopv_num--;
  290 
  291         vfs_opv_recalc();
  292 }
  293 
  294 /*
  295  * Routines having to do with the management of the vnode table.
  296  */
  297 struct vattr va_null;
  298 
  299 /*
  300  * Initialize the vnode structures and initialize each file system type.
  301  */
  302 /* ARGSUSED*/
  303 static void
  304 vfsinit(void *dummy)
  305 {
  306 
  307         namei_zone = zinit("NAMEI", MAXPATHLEN, 0, 0, 2);
  308 
  309         /*
  310          * Initialize the vnode table
  311          */
  312         vntblinit();
  313         /*
  314          * Initialize the vnode name cache
  315          */
  316         nchinit();
  317         /*
  318          * Initialize each file system type.
  319          * Vfs type numbers must be distinct from VFS_GENERIC (and VFS_VFSCONF).
  320          */
  321         vattr_null(&va_null);
  322         maxvfsconf = VFS_GENERIC + 1;
  323 }
  324 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_FIRST, vfsinit, NULL)
  325 
  326 int
  327 vfs_register(struct vfsconf *vfc)
  328 {
  329         struct sysctl_oid *oidp;
  330         struct vfsconf *vfsp;
  331 
  332         vfsp = NULL;
  333         if (vfsconf)
  334                 for (vfsp = vfsconf; vfsp->vfc_next; vfsp = vfsp->vfc_next)
  335                         if (strcmp(vfc->vfc_name, vfsp->vfc_name) == 0)
  336                                 return EEXIST;
  337 
  338         vfc->vfc_typenum = maxvfsconf++;
  339         if (vfsp)
  340                 vfsp->vfc_next = vfc;
  341         else
  342                 vfsconf = vfc;
  343         vfc->vfc_next = NULL;
  344 
  345         /*
  346          * If this filesystem has a sysctl node under vfs
  347          * (i.e. vfs.xxfs), then change the oid number of that node to 
  348          * match the filesystem's type number.  This allows user code
  349          * which uses the type number to read sysctl variables defined
  350          * by the filesystem to continue working. Since the oids are
  351          * in a sorted list, we need to make sure the order is
  352          * preserved by re-registering the oid after modifying its
  353          * number.
  354          */
  355         for (oidp = SLIST_FIRST(&sysctl__vfs_children); oidp;
  356              oidp = SLIST_NEXT(oidp, oid_link))
  357                 if (strcmp(oidp->oid_name, vfc->vfc_name) == 0) {
  358                         sysctl_unregister_oid(oidp);
  359                         oidp->oid_number = vfc->vfc_typenum;
  360                         sysctl_register_oid(oidp);
  361                 }
  362 
  363         /*
  364          * Call init function for this VFS...
  365          */
  366         (*(vfc->vfc_vfsops->vfs_init))(vfc);
  367 
  368         return 0;
  369 }
  370 
  371 
  372 int
  373 vfs_unregister(struct vfsconf *vfc)
  374 {
  375         struct vfsconf *vfsp, *prev_vfsp;
  376         int error, i, maxtypenum;
  377 
  378         i = vfc->vfc_typenum;
  379 
  380         prev_vfsp = NULL;
  381         for (vfsp = vfsconf; vfsp;
  382                         prev_vfsp = vfsp, vfsp = vfsp->vfc_next) {
  383                 if (!strcmp(vfc->vfc_name, vfsp->vfc_name))
  384                         break;
  385         }
  386         if (vfsp == NULL)
  387                 return EINVAL;
  388         if (vfsp->vfc_refcount)
  389                 return EBUSY;
  390         if (vfc->vfc_vfsops->vfs_uninit != NULL) {
  391                 error = (*vfc->vfc_vfsops->vfs_uninit)(vfsp);
  392                 if (error)
  393                         return (error);
  394         }
  395         if (prev_vfsp)
  396                 prev_vfsp->vfc_next = vfsp->vfc_next;
  397         else
  398                 vfsconf = vfsp->vfc_next;
  399         maxtypenum = VFS_GENERIC;
  400         for (vfsp = vfsconf; vfsp != NULL; vfsp = vfsp->vfc_next)
  401                 if (maxtypenum < vfsp->vfc_typenum)
  402                         maxtypenum = vfsp->vfc_typenum;
  403         maxvfsconf = maxtypenum + 1;
  404         return 0;
  405 }
  406 
  407 int
  408 vfs_modevent(module_t mod, int type, void *data)
  409 {
  410         struct vfsconf *vfc;
  411         int error = 0;
  412 
  413         vfc = (struct vfsconf *)data;
  414 
  415         switch (type) {
  416         case MOD_LOAD:
  417                 if (vfc)
  418                         error = vfs_register(vfc);
  419                 break;
  420 
  421         case MOD_UNLOAD:
  422                 if (vfc)
  423                         error = vfs_unregister(vfc);
  424                 break;
  425         default:        /* including MOD_SHUTDOWN */
  426                 break;
  427         }
  428         return (error);
  429 }

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