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/fnv_hash.h>
   43 #include <sys/kernel.h>
   44 #include <sys/linker.h>
   45 #include <sys/mount.h>
   46 #include <sys/proc.h>
   47 #include <sys/syscallsubr.h>
   48 #include <sys/sysctl.h>
   49 #include <sys/vnode.h>
   50 #include <sys/malloc.h>
   51 
   52 static int      vfs_register(struct vfsconf *);
   53 static int      vfs_unregister(struct vfsconf *);
   54 
   55 MALLOC_DEFINE(M_VNODE, "vnodes", "Dynamically allocated vnodes");
   56 
   57 /*
   58  * The highest defined VFS number.
   59  */
   60 int maxvfsconf = VFS_GENERIC + 1;
   61 
   62 /*
   63  * Single-linked list of configured VFSes.
   64  * New entries are added/deleted by vfs_register()/vfs_unregister()
   65  */
   66 struct vfsconfhead vfsconf = TAILQ_HEAD_INITIALIZER(vfsconf);
   67 
   68 /*
   69  * Loader.conf variable vfs.typenumhash enables setting vfc_typenum using a hash
   70  * calculation on vfc_name, so that it doesn't change when file systems are
   71  * loaded in a different order. This will avoid the NFS server file handles from
   72  * changing for file systems that use vfc_typenum in their fsid.
   73  */
   74 static int      vfs_typenumhash = 1;
   75 TUNABLE_INT("vfs.typenumhash", &vfs_typenumhash);
   76 SYSCTL_INT(_vfs, OID_AUTO, typenumhash, CTLFLAG_RDTUN, &vfs_typenumhash, 0,
   77     "Set vfc_typenum using a hash calculation on vfc_name, so that it does not"
   78     "change when file systems are loaded in a different order.");
   79 
   80 /*
   81  * A Zen vnode attribute structure.
   82  *
   83  * Initialized when the first filesystem registers by vfs_register().
   84  */
   85 struct vattr va_null;
   86 
   87 /*
   88  * vfs_init.c
   89  *
   90  * Allocate and fill in operations vectors.
   91  *
   92  * An undocumented feature of this approach to defining operations is that
   93  * there can be multiple entries in vfs_opv_descs for the same operations
   94  * vector. This allows third parties to extend the set of operations
   95  * supported by another layer in a binary compatibile way. For example,
   96  * assume that NFS needed to be modified to support Ficus. NFS has an entry
   97  * (probably nfs_vnopdeop_decls) declaring all the operations NFS supports by
   98  * default. Ficus could add another entry (ficus_nfs_vnodeop_decl_entensions)
   99  * listing those new operations Ficus adds to NFS, all without modifying the
  100  * NFS code. (Of couse, the OTW NFS protocol still needs to be munged, but
  101  * that is a(whole)nother story.) This is a feature.
  102  */
  103 
  104 /*
  105  * Routines having to do with the management of the vnode table.
  106  */
  107 
  108 struct vfsconf *
  109 vfs_byname(const char *name)
  110 {
  111         struct vfsconf *vfsp;
  112 
  113         if (!strcmp(name, "ffs"))
  114                 name = "ufs";
  115         TAILQ_FOREACH(vfsp, &vfsconf, vfc_list)
  116                 if (!strcmp(name, vfsp->vfc_name))
  117                         return (vfsp);
  118         return (NULL);
  119 }
  120 
  121 struct vfsconf *
  122 vfs_byname_kld(const char *fstype, struct thread *td, int *error)
  123 {
  124         struct vfsconf *vfsp;
  125         int fileid, loaded;
  126 
  127         vfsp = vfs_byname(fstype);
  128         if (vfsp != NULL)
  129                 return (vfsp);
  130 
  131         /* Try to load the respective module. */
  132         *error = kern_kldload(td, fstype, &fileid);
  133         loaded = (*error == 0);
  134         if (*error == EEXIST)
  135                 *error = 0;
  136         if (*error)
  137                 return (NULL);
  138 
  139         /* Look up again to see if the VFS was loaded. */
  140         vfsp = vfs_byname(fstype);
  141         if (vfsp == NULL) {
  142                 if (loaded)
  143                         (void)kern_kldunload(td, fileid, LINKER_UNLOAD_FORCE);
  144                 *error = ENODEV;
  145                 return (NULL);
  146         }
  147         return (vfsp);
  148 }
  149 
  150 
  151 /* Register a new filesystem type in the global table */
  152 static int
  153 vfs_register(struct vfsconf *vfc)
  154 {
  155         struct sysctl_oid *oidp;
  156         struct vfsops *vfsops;
  157         static int once;
  158         struct vfsconf *tvfc;
  159         uint32_t hashval;
  160         int secondpass;
  161 
  162         if (!once) {
  163                 vattr_null(&va_null);
  164                 once = 1;
  165         }
  166         
  167         if (vfc->vfc_version != VFS_VERSION) {
  168                 printf("ERROR: filesystem %s, unsupported ABI version %x\n",
  169                     vfc->vfc_name, vfc->vfc_version);
  170                 return (EINVAL);
  171         }
  172         if (vfs_byname(vfc->vfc_name) != NULL)
  173                 return EEXIST;
  174 
  175         if (vfs_typenumhash != 0) {
  176                 /*
  177                  * Calculate a hash on vfc_name to use for vfc_typenum. Unless
  178                  * all of 1<->255 are assigned, it is limited to 8bits since
  179                  * that is what ZFS uses from vfc_typenum and is also the
  180                  * preferred range for vfs_getnewfsid().
  181                  */
  182                 hashval = fnv_32_str(vfc->vfc_name, FNV1_32_INIT);
  183                 hashval &= 0xff;
  184                 secondpass = 0;
  185                 do {
  186                         /* Look for and fix any collision. */
  187                         TAILQ_FOREACH(tvfc, &vfsconf, vfc_list) {
  188                                 if (hashval == tvfc->vfc_typenum) {
  189                                         if (hashval == 255 && secondpass == 0) {
  190                                                 hashval = 1;
  191                                                 secondpass = 1;
  192                                         } else
  193                                                 hashval++;
  194                                         break;
  195                                 }
  196                         }
  197                 } while (tvfc != NULL);
  198                 vfc->vfc_typenum = hashval;
  199                 if (vfc->vfc_typenum >= maxvfsconf)
  200                         maxvfsconf = vfc->vfc_typenum + 1;
  201         } else
  202                 vfc->vfc_typenum = maxvfsconf++;
  203         TAILQ_INSERT_TAIL(&vfsconf, vfc, vfc_list);
  204 
  205         /*
  206          * If this filesystem has a sysctl node under vfs
  207          * (i.e. vfs.xxfs), then change the oid number of that node to 
  208          * match the filesystem's type number.  This allows user code
  209          * which uses the type number to read sysctl variables defined
  210          * by the filesystem to continue working. Since the oids are
  211          * in a sorted list, we need to make sure the order is
  212          * preserved by re-registering the oid after modifying its
  213          * number.
  214          */
  215         sysctl_lock();
  216         SLIST_FOREACH(oidp, &sysctl__vfs_children, oid_link)
  217                 if (strcmp(oidp->oid_name, vfc->vfc_name) == 0) {
  218                         sysctl_unregister_oid(oidp);
  219                         oidp->oid_number = vfc->vfc_typenum;
  220                         sysctl_register_oid(oidp);
  221                         break;
  222                 }
  223         sysctl_unlock();
  224 
  225         /*
  226          * Initialise unused ``struct vfsops'' fields, to use
  227          * the vfs_std*() functions.  Note, we need the mount
  228          * and unmount operations, at the least.  The check
  229          * for vfsops available is just a debugging aid.
  230          */
  231         KASSERT(vfc->vfc_vfsops != NULL,
  232             ("Filesystem %s has no vfsops", vfc->vfc_name));
  233         /*
  234          * Check the mount and unmount operations.
  235          */
  236         vfsops = vfc->vfc_vfsops;
  237         KASSERT(vfsops->vfs_mount != NULL,
  238             ("Filesystem %s has no mount op", vfc->vfc_name));
  239         KASSERT(vfsops->vfs_unmount != NULL,
  240             ("Filesystem %s has no unmount op", vfc->vfc_name));
  241 
  242         if (vfsops->vfs_root == NULL)
  243                 /* return file system's root vnode */
  244                 vfsops->vfs_root =      vfs_stdroot;
  245         if (vfsops->vfs_quotactl == NULL)
  246                 /* quota control */
  247                 vfsops->vfs_quotactl =  vfs_stdquotactl;
  248         if (vfsops->vfs_statfs == NULL)
  249                 /* return file system's status */
  250                 vfsops->vfs_statfs =    vfs_stdstatfs;
  251         if (vfsops->vfs_sync == NULL)
  252                 /*
  253                  * flush unwritten data (nosync)
  254                  * file systems can use vfs_stdsync
  255                  * explicitly by setting it in the
  256                  * vfsop vector.
  257                  */
  258                 vfsops->vfs_sync =      vfs_stdnosync;
  259         if (vfsops->vfs_vget == NULL)
  260                 /* convert an inode number to a vnode */
  261                 vfsops->vfs_vget =      vfs_stdvget;
  262         if (vfsops->vfs_fhtovp == NULL)
  263                 /* turn an NFS file handle into a vnode */
  264                 vfsops->vfs_fhtovp =    vfs_stdfhtovp;
  265         if (vfsops->vfs_checkexp == NULL)
  266                 /* check if file system is exported */
  267                 vfsops->vfs_checkexp =  vfs_stdcheckexp;
  268         if (vfsops->vfs_init == NULL)
  269                 /* file system specific initialisation */
  270                 vfsops->vfs_init =      vfs_stdinit;
  271         if (vfsops->vfs_uninit == NULL)
  272                 /* file system specific uninitialisation */
  273                 vfsops->vfs_uninit =    vfs_stduninit;
  274         if (vfsops->vfs_extattrctl == NULL)
  275                 /* extended attribute control */
  276                 vfsops->vfs_extattrctl = vfs_stdextattrctl;
  277         if (vfsops->vfs_sysctl == NULL)
  278                 vfsops->vfs_sysctl = vfs_stdsysctl;
  279         
  280         /*
  281          * Call init function for this VFS...
  282          */
  283         (*(vfc->vfc_vfsops->vfs_init))(vfc);
  284 
  285         return 0;
  286 }
  287 
  288 
  289 /* Remove registration of a filesystem type */
  290 static int
  291 vfs_unregister(struct vfsconf *vfc)
  292 {
  293         struct vfsconf *vfsp;
  294         int error, i, maxtypenum;
  295 
  296         i = vfc->vfc_typenum;
  297 
  298         vfsp = vfs_byname(vfc->vfc_name);
  299         if (vfsp == NULL)
  300                 return EINVAL;
  301         if (vfsp->vfc_refcount)
  302                 return EBUSY;
  303         if (vfc->vfc_vfsops->vfs_uninit != NULL) {
  304                 error = (*vfc->vfc_vfsops->vfs_uninit)(vfsp);
  305                 if (error)
  306                         return (error);
  307         }
  308         TAILQ_REMOVE(&vfsconf, vfsp, vfc_list);
  309         maxtypenum = VFS_GENERIC;
  310         TAILQ_FOREACH(vfsp, &vfsconf, vfc_list)
  311                 if (maxtypenum < vfsp->vfc_typenum)
  312                         maxtypenum = vfsp->vfc_typenum;
  313         maxvfsconf = maxtypenum + 1;
  314         return 0;
  315 }
  316 
  317 /*
  318  * Standard kernel module handling code for filesystem modules.
  319  * Referenced from VFS_SET().
  320  */
  321 int
  322 vfs_modevent(module_t mod, int type, void *data)
  323 {
  324         struct vfsconf *vfc;
  325         int error = 0;
  326 
  327         vfc = (struct vfsconf *)data;
  328 
  329         switch (type) {
  330         case MOD_LOAD:
  331                 if (vfc)
  332                         error = vfs_register(vfc);
  333                 break;
  334 
  335         case MOD_UNLOAD:
  336                 if (vfc)
  337                         error = vfs_unregister(vfc);
  338                 break;
  339         default:
  340                 error = EOPNOTSUPP;
  341                 break;
  342         }
  343         return (error);
  344 }
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FreeBSD/Linux Kernel Cross Reference sys/kern/vfs_init.c

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sys/kern/vfs_init.c
