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  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)vfs_init.c  8.3 (Berkeley) 1/4/94
   35  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD$");
   39 
   40 #include <sys/param.h>
   41 #include <sys/systm.h>
   42 #include <sys/kernel.h>
   43 #include <sys/linker.h>
   44 #include <sys/mount.h>
   45 #include <sys/proc.h>
   46 #include <sys/syscallsubr.h>
   47 #include <sys/sysctl.h>
   48 #include <sys/vnode.h>
   49 #include <sys/malloc.h>
   50 
   51 static int      vfs_register(struct vfsconf *);
   52 static int      vfs_unregister(struct vfsconf *);
   53 
   54 MALLOC_DEFINE(M_VNODE, "vnodes", "Dynamically allocated vnodes");
   55 
   56 /*
   57  * The highest defined VFS number.
   58  */
   59 int maxvfsconf = VFS_GENERIC + 1;
   60 
   61 /*
   62  * Single-linked list of configured VFSes.
   63  * New entries are added/deleted by vfs_register()/vfs_unregister()
   64  */
   65 struct vfsconfhead vfsconf = TAILQ_HEAD_INITIALIZER(vfsconf);
   66 
   67 /*
   68  * A Zen vnode attribute structure.
   69  *
   70  * Initialized when the first filesystem registers by vfs_register().
   71  */
   72 struct vattr va_null;
   73 
   74 /*
   75  * vfs_init.c
   76  *
   77  * Allocate and fill in operations vectors.
   78  *
   79  * An undocumented feature of this approach to defining operations is that
   80  * there can be multiple entries in vfs_opv_descs for the same operations
   81  * vector. This allows third parties to extend the set of operations
   82  * supported by another layer in a binary compatibile way. For example,
   83  * assume that NFS needed to be modified to support Ficus. NFS has an entry
   84  * (probably nfs_vnopdeop_decls) declaring all the operations NFS supports by
   85  * default. Ficus could add another entry (ficus_nfs_vnodeop_decl_entensions)
   86  * listing those new operations Ficus adds to NFS, all without modifying the
   87  * NFS code. (Of couse, the OTW NFS protocol still needs to be munged, but
   88  * that is a(whole)nother story.) This is a feature.
   89  */
   90 
   91 /*
   92  * Routines having to do with the management of the vnode table.
   93  */
   94 
   95 struct vfsconf *
   96 vfs_byname(const char *name)
   97 {
   98         struct vfsconf *vfsp;
   99 
  100         if (!strcmp(name, "ffs"))
  101                 name = "ufs";
  102         TAILQ_FOREACH(vfsp, &vfsconf, vfc_list)
  103                 if (!strcmp(name, vfsp->vfc_name))
  104                         return (vfsp);
  105         return (NULL);
  106 }
  107 
  108 struct vfsconf *
  109 vfs_byname_kld(const char *fstype, struct thread *td, int *error)
  110 {
  111         struct vfsconf *vfsp;
  112         int fileid;
  113 
  114         vfsp = vfs_byname(fstype);
  115         if (vfsp != NULL)
  116                 return (vfsp);
  117 
  118         /* Try to load the respective module. */
  119         *error = kern_kldload(td, fstype, &fileid);
  120         if (*error)
  121                 return (NULL);
  122 
  123         /* Look up again to see if the VFS was loaded. */
  124         vfsp = vfs_byname(fstype);
  125         if (vfsp == NULL) {
  126                 (void)kern_kldunload(td, fileid, LINKER_UNLOAD_FORCE);
  127                 *error = ENODEV;
  128                 return (NULL);
  129         }
  130         return (vfsp);
  131 }
  132 
  133 
  134 /* Register a new filesystem type in the global table */
  135 static int
  136 vfs_register(struct vfsconf *vfc)
  137 {
  138         struct sysctl_oid *oidp;
  139         struct vfsops *vfsops;
  140         static int once;
  141 
  142         if (!once) {
  143                 vattr_null(&va_null);
  144                 once = 1;
  145         }
  146         
  147         if (vfc->vfc_version != VFS_VERSION) {
  148                 printf("ERROR: filesystem %s, unsupported ABI version %x\n",
  149                     vfc->vfc_name, vfc->vfc_version);
  150                 return (EINVAL);
  151         }
  152         if (vfs_byname(vfc->vfc_name) != NULL)
  153                 return EEXIST;
  154 
  155         vfc->vfc_typenum = maxvfsconf++;
  156         TAILQ_INSERT_TAIL(&vfsconf, vfc, vfc_list);
  157 
  158         /*
  159          * If this filesystem has a sysctl node under vfs
  160          * (i.e. vfs.xxfs), then change the oid number of that node to 
  161          * match the filesystem's type number.  This allows user code
  162          * which uses the type number to read sysctl variables defined
  163          * by the filesystem to continue working. Since the oids are
  164          * in a sorted list, we need to make sure the order is
  165          * preserved by re-registering the oid after modifying its
  166          * number.
  167          */
  168         SLIST_FOREACH(oidp, &sysctl__vfs_children, oid_link)
  169                 if (strcmp(oidp->oid_name, vfc->vfc_name) == 0) {
  170                         sysctl_unregister_oid(oidp);
  171                         oidp->oid_number = vfc->vfc_typenum;
  172                         sysctl_register_oid(oidp);
  173                 }
  174 
  175         /*
  176          * Initialise unused ``struct vfsops'' fields, to use
  177          * the vfs_std*() functions.  Note, we need the mount
  178          * and unmount operations, at the least.  The check
  179          * for vfsops available is just a debugging aid.
  180          */
  181         KASSERT(vfc->vfc_vfsops != NULL,
  182             ("Filesystem %s has no vfsops", vfc->vfc_name));
  183         /*
  184          * Check the mount and unmount operations.
  185          */
  186         vfsops = vfc->vfc_vfsops;
  187         KASSERT(vfsops->vfs_mount != NULL,
  188             ("Filesystem %s has no mount op", vfc->vfc_name));
  189         KASSERT(vfsops->vfs_unmount != NULL,
  190             ("Filesystem %s has no unmount op", vfc->vfc_name));
  191 
  192         if (vfsops->vfs_root == NULL)
  193                 /* return file system's root vnode */
  194                 vfsops->vfs_root =      vfs_stdroot;
  195         if (vfsops->vfs_quotactl == NULL)
  196                 /* quota control */
  197                 vfsops->vfs_quotactl =  vfs_stdquotactl;
  198         if (vfsops->vfs_statfs == NULL)
  199                 /* return file system's status */
  200                 vfsops->vfs_statfs =    vfs_stdstatfs;
  201         if (vfsops->vfs_sync == NULL)
  202                 /*
  203                  * flush unwritten data (nosync)
  204                  * file systems can use vfs_stdsync
  205                  * explicitly by setting it in the
  206                  * vfsop vector.
  207                  */
  208                 vfsops->vfs_sync =      vfs_stdnosync;
  209         if (vfsops->vfs_vget == NULL)
  210                 /* convert an inode number to a vnode */
  211                 vfsops->vfs_vget =      vfs_stdvget;
  212         if (vfsops->vfs_fhtovp == NULL)
  213                 /* turn an NFS file handle into a vnode */
  214                 vfsops->vfs_fhtovp =    vfs_stdfhtovp;
  215         if (vfsops->vfs_checkexp == NULL)
  216                 /* check if file system is exported */
  217                 vfsops->vfs_checkexp =  vfs_stdcheckexp;
  218         if (vfsops->vfs_init == NULL)
  219                 /* file system specific initialisation */
  220                 vfsops->vfs_init =      vfs_stdinit;
  221         if (vfsops->vfs_uninit == NULL)
  222                 /* file system specific uninitialisation */
  223                 vfsops->vfs_uninit =    vfs_stduninit;
  224         if (vfsops->vfs_extattrctl == NULL)
  225                 /* extended attribute control */
  226                 vfsops->vfs_extattrctl = vfs_stdextattrctl;
  227         if (vfsops->vfs_sysctl == NULL)
  228                 vfsops->vfs_sysctl = vfs_stdsysctl;
  229         
  230         /*
  231          * Call init function for this VFS...
  232          */
  233         (*(vfc->vfc_vfsops->vfs_init))(vfc);
  234 
  235         return 0;
  236 }
  237 
  238 
  239 /* Remove registration of a filesystem type */
  240 static int
  241 vfs_unregister(struct vfsconf *vfc)
  242 {
  243         struct vfsconf *vfsp;
  244         int error, i, maxtypenum;
  245 
  246         i = vfc->vfc_typenum;
  247 
  248         vfsp = vfs_byname(vfc->vfc_name);
  249         if (vfsp == NULL)
  250                 return EINVAL;
  251         if (vfsp->vfc_refcount)
  252                 return EBUSY;
  253         if (vfc->vfc_vfsops->vfs_uninit != NULL) {
  254                 error = (*vfc->vfc_vfsops->vfs_uninit)(vfsp);
  255                 if (error)
  256                         return (error);
  257         }
  258         TAILQ_REMOVE(&vfsconf, vfsp, vfc_list);
  259         maxtypenum = VFS_GENERIC;
  260         TAILQ_FOREACH(vfsp, &vfsconf, vfc_list)
  261                 if (maxtypenum < vfsp->vfc_typenum)
  262                         maxtypenum = vfsp->vfc_typenum;
  263         maxvfsconf = maxtypenum + 1;
  264         return 0;
  265 }
  266 
  267 /*
  268  * Standard kernel module handling code for filesystem modules.
  269  * Referenced from VFS_SET().
  270  */
  271 int
  272 vfs_modevent(module_t mod, int type, void *data)
  273 {
  274         struct vfsconf *vfc;
  275         int error = 0;
  276 
  277         vfc = (struct vfsconf *)data;
  278 
  279         switch (type) {
  280         case MOD_LOAD:
  281                 if (vfc)
  282                         error = vfs_register(vfc);
  283                 break;
  284 
  285         case MOD_UNLOAD:
  286                 if (vfc)
  287                         error = vfs_unregister(vfc);
  288                 break;
  289         default:
  290                 error = EOPNOTSUPP;
  291                 break;
  292         }
  293         return (error);
  294 }
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FreeBSD/Linux Kernel Cross Reference sys/kern/vfs_init.c

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sys/kern/vfs_init.c
