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

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * 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. 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/fnv_hash.h>
    #include <sys/jail.h>
    #include <sys/kernel.h>
    #include <sys/linker.h>
    #include <sys/mount.h>
    #include <sys/proc.h>
    #include <sys/sx.h>
    #include <sys/syscallsubr.h>
    #include <sys/sysctl.h>
    #include <sys/vnode.h>
    #include <sys/malloc.h>
    
    static int      vfs_register(struct vfsconf *);
    static int      vfs_unregister(struct vfsconf *);
    
    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 vfsconfhead vfsconf = TAILQ_HEAD_INITIALIZER(vfsconf);
    struct sx vfsconf_sx;
    SX_SYSINIT(vfsconf, &vfsconf_sx, "vfsconf");
    
    /*
     * Loader.conf variable vfs.typenumhash enables setting vfc_typenum using a hash
     * calculation on vfc_name, so that it doesn't change when file systems are
     * loaded in a different order. This will avoid the NFS server file handles from
     * changing for file systems that use vfc_typenum in their fsid.
     */
    static int      vfs_typenumhash = 1;
    SYSCTL_INT(_vfs, OID_AUTO, typenumhash, CTLFLAG_RDTUN, &vfs_typenumhash, 0,
        "Set vfc_typenum using a hash calculation on vfc_name, so that it does not"
        "change when file systems are loaded in a different order.");
    
    /*
     * A Zen vnode attribute structure.
     *
     * Initialized when the first filesystem registers by vfs_register().
     */
    struct vattr va_null;
    
    /*
     * 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.
    */
   
   /*
    * Routines having to do with the management of the vnode table.
    */
   
   static struct vfsconf *
   vfs_byname_locked(const char *name)
   {
           struct vfsconf *vfsp;
   
           sx_assert(&vfsconf_sx, SA_LOCKED);
           if (!strcmp(name, "ffs"))
                   name = "ufs";
           TAILQ_FOREACH(vfsp, &vfsconf, vfc_list) {
                   if (!strcmp(name, vfsp->vfc_name))
                           return (vfsp);
           }
           return (NULL);
   }
   
   struct vfsconf *
   vfs_byname(const char *name)
   {
           struct vfsconf *vfsp;
   
           vfsconf_slock();
           vfsp = vfs_byname_locked(name);
           vfsconf_sunlock();
           return (vfsp);
   }
   
   struct vfsconf *
   vfs_byname_kld(const char *fstype, struct thread *td, int *error)
   {
           struct vfsconf *vfsp;
           int fileid, loaded;
   
           vfsp = vfs_byname(fstype);
           if (vfsp != NULL)
                   return (vfsp);
   
           /* Try to load the respective module. */
           *error = kern_kldload(td, fstype, &fileid);
           loaded = (*error == 0);
           if (*error == EEXIST)
                   *error = 0;
           if (*error)
                   return (NULL);
   
           /* Look up again to see if the VFS was loaded. */
           vfsp = vfs_byname(fstype);
           if (vfsp == NULL) {
                   if (loaded)
                           (void)kern_kldunload(td, fileid, LINKER_UNLOAD_FORCE);
                   *error = ENODEV;
                   return (NULL);
           }
           return (vfsp);
   }
   
   static int
   vfs_mount_sigdefer(struct mount *mp)
   {
           int prev_stops, rc;
   
           TSRAW(curthread, TS_ENTER, "VFS_MOUNT", mp->mnt_vfc->vfc_name);
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           rc = (*mp->mnt_vfc->vfc_vfsops_sd->vfs_mount)(mp);
           sigallowstop(prev_stops);
           TSRAW(curthread, TS_EXIT, "VFS_MOUNT", mp->mnt_vfc->vfc_name);
           return (rc);
   }
   
   static int
   vfs_unmount_sigdefer(struct mount *mp, int mntflags)
   {
           int prev_stops, rc;
   
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           rc = (*mp->mnt_vfc->vfc_vfsops_sd->vfs_unmount)(mp, mntflags);
           sigallowstop(prev_stops);
           return (rc);
   }
   
   static int
   vfs_root_sigdefer(struct mount *mp, int flags, struct vnode **vpp)
   {
           int prev_stops, rc;
   
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           rc = (*mp->mnt_vfc->vfc_vfsops_sd->vfs_root)(mp, flags, vpp);
           sigallowstop(prev_stops);
           return (rc);
   }
   
   static int
   vfs_cachedroot_sigdefer(struct mount *mp, int flags, struct vnode **vpp)
   {
           int prev_stops, rc;
   
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           rc = (*mp->mnt_vfc->vfc_vfsops_sd->vfs_cachedroot)(mp, flags, vpp);
           sigallowstop(prev_stops);
           return (rc);
   }
   
   static int
   vfs_quotactl_sigdefer(struct mount *mp, int cmd, uid_t uid, void *arg)
   {
           int prev_stops, rc;
   
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           rc = (*mp->mnt_vfc->vfc_vfsops_sd->vfs_quotactl)(mp, cmd, uid, arg);
           sigallowstop(prev_stops);
           return (rc);
   }
   
   static int
   vfs_statfs_sigdefer(struct mount *mp, struct statfs *sbp)
   {
           int prev_stops, rc;
   
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           rc = (*mp->mnt_vfc->vfc_vfsops_sd->vfs_statfs)(mp, sbp);
           sigallowstop(prev_stops);
           return (rc);
   }
   
   static int
   vfs_sync_sigdefer(struct mount *mp, int waitfor)
   {
           int prev_stops, rc;
   
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           rc = (*mp->mnt_vfc->vfc_vfsops_sd->vfs_sync)(mp, waitfor);
           sigallowstop(prev_stops);
           return (rc);
   }
   
   static int
   vfs_vget_sigdefer(struct mount *mp, ino_t ino, int flags, struct vnode **vpp)
   {
           int prev_stops, rc;
   
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           rc = (*mp->mnt_vfc->vfc_vfsops_sd->vfs_vget)(mp, ino, flags, vpp);
           sigallowstop(prev_stops);
           return (rc);
   }
   
   static int
   vfs_fhtovp_sigdefer(struct mount *mp, struct fid *fidp, int flags,
       struct vnode **vpp)
   {
           int prev_stops, rc;
   
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           rc = (*mp->mnt_vfc->vfc_vfsops_sd->vfs_fhtovp)(mp, fidp, flags, vpp);
           sigallowstop(prev_stops);
           return (rc);
   }
   
   static int
   vfs_checkexp_sigdefer(struct mount *mp, struct sockaddr *nam, uint64_t *exflg,
       struct ucred **credp, int *numsecflavors, int *secflavors)
   {
           int prev_stops, rc;
   
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           rc = (*mp->mnt_vfc->vfc_vfsops_sd->vfs_checkexp)(mp, nam, exflg, credp,
               numsecflavors, secflavors);
           sigallowstop(prev_stops);
           return (rc);
   }
   
   static int
   vfs_extattrctl_sigdefer(struct mount *mp, int cmd, struct vnode *filename_vp,
       int attrnamespace, const char *attrname)
   {
           int prev_stops, rc;
   
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           rc = (*mp->mnt_vfc->vfc_vfsops_sd->vfs_extattrctl)(mp, cmd,
               filename_vp, attrnamespace, attrname);
           sigallowstop(prev_stops);
           return (rc);
   }
   
   static int
   vfs_sysctl_sigdefer(struct mount *mp, fsctlop_t op, struct sysctl_req *req)
   {
           int prev_stops, rc;
   
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           rc = (*mp->mnt_vfc->vfc_vfsops_sd->vfs_sysctl)(mp, op, req);
           sigallowstop(prev_stops);
           return (rc);
   }
   
   static void
   vfs_susp_clean_sigdefer(struct mount *mp)
   {
           int prev_stops;
   
           if (*mp->mnt_vfc->vfc_vfsops_sd->vfs_susp_clean == NULL)
                   return;
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           (*mp->mnt_vfc->vfc_vfsops_sd->vfs_susp_clean)(mp);
           sigallowstop(prev_stops);
   }
   
   static void
   vfs_reclaim_lowervp_sigdefer(struct mount *mp, struct vnode *vp)
   {
           int prev_stops;
   
           if (*mp->mnt_vfc->vfc_vfsops_sd->vfs_reclaim_lowervp == NULL)
                   return;
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           (*mp->mnt_vfc->vfc_vfsops_sd->vfs_reclaim_lowervp)(mp, vp);
           sigallowstop(prev_stops);
   }
   
   static void
   vfs_unlink_lowervp_sigdefer(struct mount *mp, struct vnode *vp)
   {
           int prev_stops;
   
           if (*mp->mnt_vfc->vfc_vfsops_sd->vfs_unlink_lowervp == NULL)
                   return;
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           (*(mp)->mnt_vfc->vfc_vfsops_sd->vfs_unlink_lowervp)(mp, vp);
           sigallowstop(prev_stops);
   }
   
   static void
   vfs_purge_sigdefer(struct mount *mp)
   {
           int prev_stops;
   
           prev_stops = sigdeferstop(SIGDEFERSTOP_SILENT);
           (*mp->mnt_vfc->vfc_vfsops_sd->vfs_purge)(mp);
           sigallowstop(prev_stops);
   }
   
   static struct vfsops vfsops_sigdefer = {
           .vfs_mount =            vfs_mount_sigdefer,
           .vfs_unmount =          vfs_unmount_sigdefer,
           .vfs_root =             vfs_root_sigdefer,
           .vfs_cachedroot =       vfs_cachedroot_sigdefer,
           .vfs_quotactl =         vfs_quotactl_sigdefer,
           .vfs_statfs =           vfs_statfs_sigdefer,
           .vfs_sync =             vfs_sync_sigdefer,
           .vfs_vget =             vfs_vget_sigdefer,
           .vfs_fhtovp =           vfs_fhtovp_sigdefer,
           .vfs_checkexp =         vfs_checkexp_sigdefer,
           .vfs_extattrctl =       vfs_extattrctl_sigdefer,
           .vfs_sysctl =           vfs_sysctl_sigdefer,
           .vfs_susp_clean =       vfs_susp_clean_sigdefer,
           .vfs_reclaim_lowervp =  vfs_reclaim_lowervp_sigdefer,
           .vfs_unlink_lowervp =   vfs_unlink_lowervp_sigdefer,
           .vfs_purge =            vfs_purge_sigdefer,
   
   };
   
   /* Register a new filesystem type in the global table */
   static int
   vfs_register(struct vfsconf *vfc)
   {
           struct sysctl_oid *oidp;
           struct vfsops *vfsops;
           static int once;
           struct vfsconf *tvfc;
           uint32_t hashval;
           int secondpass;
   
           if (!once) {
                   vattr_null(&va_null);
                   once = 1;
           }
   
           if (vfc->vfc_version != VFS_VERSION) {
                   printf("ERROR: filesystem %s, unsupported ABI version %x\n",
                       vfc->vfc_name, vfc->vfc_version);
                   return (EINVAL);
           }
           vfsconf_lock();
           if (vfs_byname_locked(vfc->vfc_name) != NULL) {
                   vfsconf_unlock();
                   return (EEXIST);
           }
   
           if (vfs_typenumhash != 0) {
                   /*
                    * Calculate a hash on vfc_name to use for vfc_typenum. Unless
                    * all of 1<->255 are assigned, it is limited to 8bits since
                    * that is what ZFS uses from vfc_typenum and is also the
                    * preferred range for vfs_getnewfsid().
                    */
                   hashval = fnv_32_str(vfc->vfc_name, FNV1_32_INIT);
                   hashval &= 0xff;
                   secondpass = 0;
                   do {
                           /* Look for and fix any collision. */
                           TAILQ_FOREACH(tvfc, &vfsconf, vfc_list) {
                                   if (hashval == tvfc->vfc_typenum) {
                                           if (hashval == 255 && secondpass == 0) {
                                                   hashval = 1;
                                                   secondpass = 1;
                                           } else
                                                   hashval++;
                                           break;
                                   }
                           }
                   } while (tvfc != NULL);
                   vfc->vfc_typenum = hashval;
                   if (vfc->vfc_typenum >= maxvfsconf)
                           maxvfsconf = vfc->vfc_typenum + 1;
           } else
                   vfc->vfc_typenum = maxvfsconf++;
           TAILQ_INSERT_TAIL(&vfsconf, vfc, vfc_list);
   
           /*
            * 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,
               ("Filesystem %s has no mount op", vfc->vfc_name));
           KASSERT(vfsops->vfs_unmount != NULL,
               ("Filesystem %s has no unmount op", vfc->vfc_name));
   
           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_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;
   
           if ((vfc->vfc_flags & VFCF_SBDRY) != 0) {
                   vfc->vfc_vfsops_sd = vfc->vfc_vfsops;
                   vfc->vfc_vfsops = &vfsops_sigdefer;
           }
   
           if (vfc->vfc_flags & VFCF_JAIL)
                   prison_add_vfs(vfc);
   
           /*
            * Call init function for this VFS...
            */
           if ((vfc->vfc_flags & VFCF_SBDRY) != 0)
                   vfc->vfc_vfsops_sd->vfs_init(vfc);
           else
                   vfc->vfc_vfsops->vfs_init(vfc);
           vfsconf_unlock();
   
           /*
            * 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.
            */
           sysctl_wlock();
           SLIST_FOREACH(oidp, SYSCTL_CHILDREN(&sysctl___vfs), 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);
                           break;
                   }
           }
           sysctl_wunlock();
   
           return (0);
   }
   
   /* Remove registration of a filesystem type */
   static int
   vfs_unregister(struct vfsconf *vfc)
   {
           struct vfsconf *vfsp;
           int error, maxtypenum;
   
           vfsconf_lock();
           vfsp = vfs_byname_locked(vfc->vfc_name);
           if (vfsp == NULL) {
                   vfsconf_unlock();
                   return (EINVAL);
           }
           if (vfsp->vfc_refcount != 0) {
                   vfsconf_unlock();
                   return (EBUSY);
           }
           error = 0;
           if ((vfc->vfc_flags & VFCF_SBDRY) != 0) {
                   if (vfc->vfc_vfsops_sd->vfs_uninit != NULL)
                           error = vfc->vfc_vfsops_sd->vfs_uninit(vfsp);
           } else {
                   if (vfc->vfc_vfsops->vfs_uninit != NULL) {
                           error = vfc->vfc_vfsops->vfs_uninit(vfsp);
           }
           if (error != 0) {
                   vfsconf_unlock();
                   return (error);
           }
           }
           TAILQ_REMOVE(&vfsconf, vfsp, vfc_list);
           maxtypenum = VFS_GENERIC;
           TAILQ_FOREACH(vfsp, &vfsconf, vfc_list)
                   if (maxtypenum < vfsp->vfc_typenum)
                           maxtypenum = vfsp->vfc_typenum;
           maxvfsconf = maxtypenum + 1;
           vfsconf_unlock();
           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:
                   error = EOPNOTSUPP;
                   break;
           }
           return (error);
   }

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