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

     /*
      * 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. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 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.
     *
     *
     * $FreeBSD$
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/buf.h>
    #include <sys/conf.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mount.h>
    #include <sys/unistd.h>
    #include <sys/vnode.h>
    #include <sys/poll.h>
    
    #include <machine/limits.h>
    
    #include <vm/vm.h>
    #include <vm/vm_object.h>
    #include <vm/vm_page.h>
    #include <vm/vm_pager.h>
    #include <vm/vnode_pager.h>
    
    static int      vop_nolookup __P((struct vop_lookup_args *));
    static int      vop_nostrategy __P((struct vop_strategy_args *));
    
    /*
     * This vnode table stores what we want to do if the filesystem doesn't
     * implement a particular VOP.
     *
     * If there is no specific entry here, we will return EOPNOTSUPP.
     *
     */
    
    vop_t **default_vnodeop_p;
    static struct vnodeopv_entry_desc default_vnodeop_entries[] = {
            { &vop_default_desc,            (vop_t *) vop_eopnotsupp },
            { &vop_advlock_desc,            (vop_t *) vop_einval },
            { &vop_bwrite_desc,             (vop_t *) vop_stdbwrite },
            { &vop_close_desc,              (vop_t *) vop_null },
            { &vop_createvobject_desc,      (vop_t *) vop_stdcreatevobject },
            { &vop_destroyvobject_desc,     (vop_t *) vop_stddestroyvobject },
            { &vop_fsync_desc,              (vop_t *) vop_null },
            { &vop_getvobject_desc,         (vop_t *) vop_stdgetvobject },
            { &vop_ioctl_desc,              (vop_t *) vop_enotty },
            { &vop_islocked_desc,           (vop_t *) vop_noislocked },
            { &vop_lease_desc,              (vop_t *) vop_null },
            { &vop_lock_desc,               (vop_t *) vop_nolock },
            { &vop_mmap_desc,               (vop_t *) vop_einval },
            { &vop_lookup_desc,             (vop_t *) vop_nolookup },
            { &vop_open_desc,               (vop_t *) vop_null },
            { &vop_pathconf_desc,           (vop_t *) vop_einval },
            { &vop_poll_desc,               (vop_t *) vop_nopoll },
            { &vop_readlink_desc,           (vop_t *) vop_einval },
            { &vop_reallocblks_desc,        (vop_t *) vop_eopnotsupp },
            { &vop_revoke_desc,             (vop_t *) vop_revoke },
            { &vop_strategy_desc,           (vop_t *) vop_nostrategy },
            { &vop_unlock_desc,             (vop_t *) vop_nounlock },
            { &vop_getacl_desc,             (vop_t *) vop_eopnotsupp },
            { &vop_setacl_desc,             (vop_t *) vop_eopnotsupp },
            { &vop_aclcheck_desc,           (vop_t *) vop_eopnotsupp },
           { &vop_getextattr_desc,         (vop_t *) vop_eopnotsupp },
           { &vop_setextattr_desc,         (vop_t *) vop_eopnotsupp },
           { NULL, NULL }
   };
   
   static struct vnodeopv_desc default_vnodeop_opv_desc =
           { &default_vnodeop_p, default_vnodeop_entries };
   
   VNODEOP_SET(default_vnodeop_opv_desc);
   
   int
   vop_eopnotsupp(struct vop_generic_args *ap)
   {
           /*
           printf("vop_notsupp[%s]\n", ap->a_desc->vdesc_name);
           */
   
           return (EOPNOTSUPP);
   }
   
   int
   vop_ebadf(struct vop_generic_args *ap)
   {
   
           return (EBADF);
   }
   
   int
   vop_enotty(struct vop_generic_args *ap)
   {
   
           return (ENOTTY);
   }
   
   int
   vop_einval(struct vop_generic_args *ap)
   {
   
           return (EINVAL);
   }
   
   int
   vop_null(struct vop_generic_args *ap)
   {
   
           return (0);
   }
   
   int
   vop_defaultop(struct vop_generic_args *ap)
   {
   
           return (VOCALL(default_vnodeop_p, ap->a_desc->vdesc_offset, ap));
   }
   
   int
   vop_panic(struct vop_generic_args *ap)
   {
   
           panic("filesystem goof: vop_panic[%s]", ap->a_desc->vdesc_name);
   }
   
   static int
   vop_nolookup(ap)
           struct vop_lookup_args /* {
                   struct vnode *a_dvp;
                   struct vnode **a_vpp;
                   struct componentname *a_cnp;
           } */ *ap;
   {
   
           *ap->a_vpp = NULL;
           return (ENOTDIR);
   }
   
   /*
    *      vop_nostrategy:
    *
    *      Strategy routine for VFS devices that have none.
    *
    *      B_ERROR and B_INVAL must be cleared prior to calling any strategy
    *      routine.  Typically this is done for a B_READ strategy call.  Typically
    *      B_INVAL is assumed to already be clear prior to a write and should not
    *      be cleared manually unless you just made the buffer invalid.  B_ERROR
    *      should be cleared either way.
    */
   
   static int
   vop_nostrategy (struct vop_strategy_args *ap)
   {
           printf("No strategy for buffer at %p\n", ap->a_bp);
           vprint("", ap->a_vp);
           vprint("", ap->a_bp->b_vp);
           ap->a_bp->b_flags |= B_ERROR;
           ap->a_bp->b_error = EOPNOTSUPP;
           biodone(ap->a_bp);
           return (EOPNOTSUPP);
   }
   
   int
   vop_stdpathconf(ap)
           struct vop_pathconf_args /* {
           struct vnode *a_vp;
           int a_name;
           int *a_retval;
           } */ *ap;
   {
   
           switch (ap->a_name) {
                   case _PC_LINK_MAX:
                           *ap->a_retval = LINK_MAX;
                           return (0);
                   case _PC_MAX_CANON:
                           *ap->a_retval = MAX_CANON;
                           return (0);
                   case _PC_MAX_INPUT:
                           *ap->a_retval = MAX_INPUT;
                           return (0);
                   case _PC_PIPE_BUF:
                           *ap->a_retval = PIPE_BUF;
                           return (0);
                   case _PC_CHOWN_RESTRICTED:
                           *ap->a_retval = 1;
                           return (0);
                   case _PC_VDISABLE:
                           *ap->a_retval = _POSIX_VDISABLE;
                           return (0);
                   default:
                           return (EINVAL);
           }
           /* NOTREACHED */
   }
   
   /*
    * Standard lock, unlock and islocked functions.
    *
    * These depend on the lock structure being the first element in the
    * inode, ie: vp->v_data points to the the lock!
    */
   int
   vop_stdlock(ap)
           struct vop_lock_args /* {
                   struct vnode *a_vp;
                   int a_flags;
                   struct proc *a_p;
           } */ *ap;
   {               
           struct lock *l;
   
           if ((l = (struct lock *)ap->a_vp->v_data) == NULL) {
                   if (ap->a_flags & LK_INTERLOCK)
                           simple_unlock(&ap->a_vp->v_interlock);
                   return 0;
           }
   
   #ifndef DEBUG_LOCKS
           return (lockmgr(l, ap->a_flags, &ap->a_vp->v_interlock, ap->a_p));
   #else
           return (debuglockmgr(l, ap->a_flags, &ap->a_vp->v_interlock, ap->a_p,
               "vop_stdlock", ap->a_vp->filename, ap->a_vp->line));
   #endif
   }
   
   int
   vop_stdunlock(ap)
           struct vop_unlock_args /* {
                   struct vnode *a_vp;
                   int a_flags;
                   struct proc *a_p;
           } */ *ap;
   {
           struct lock *l;
   
           if ((l = (struct lock *)ap->a_vp->v_data) == NULL) {
                   if (ap->a_flags & LK_INTERLOCK)
                           simple_unlock(&ap->a_vp->v_interlock);
                   return 0;
           }
   
           return (lockmgr(l, ap->a_flags | LK_RELEASE, &ap->a_vp->v_interlock, 
               ap->a_p));
   }
   
   int
   vop_stdislocked(ap)
           struct vop_islocked_args /* {
                   struct vnode *a_vp;
                   struct proc *a_p;
           } */ *ap;
   {
           struct lock *l;
   
           if ((l = (struct lock *)ap->a_vp->v_data) == NULL)
                   return 0;
   
           return (lockstatus(l, ap->a_p));
   }
   
   /*
    * Return true for select/poll.
    */
   int
   vop_nopoll(ap)
           struct vop_poll_args /* {
                   struct vnode *a_vp;
                   int  a_events;
                   struct ucred *a_cred;
                   struct proc *a_p;
           } */ *ap;
   {
           /*
            * Return true for read/write.  If the user asked for something
            * special, return POLLNVAL, so that clients have a way of
            * determining reliably whether or not the extended
            * functionality is present without hard-coding knowledge
            * of specific filesystem implementations.
            */
           if (ap->a_events & ~POLLSTANDARD)
                   return (POLLNVAL);
   
           return (ap->a_events & (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
   }
   
   /*
    * Implement poll for local filesystems that support it.
    */
   int
   vop_stdpoll(ap)
           struct vop_poll_args /* {
                   struct vnode *a_vp;
                   int  a_events;
                   struct ucred *a_cred;
                   struct proc *a_p;
           } */ *ap;
   {
           if (ap->a_events & ~POLLSTANDARD)
                   return (vn_pollrecord(ap->a_vp, ap->a_p, ap->a_events));
           return (ap->a_events & (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
   }
   
   int
   vop_stdbwrite(ap)
           struct vop_bwrite_args *ap;
   {
           return (bwrite(ap->a_bp));
   }
   
   /*
    * Stubs to use when there is no locking to be done on the underlying object.
    * A minimal shared lock is necessary to ensure that the underlying object
    * is not revoked while an operation is in progress. So, an active shared
    * count is maintained in an auxillary vnode lock structure.
    */
   int
   vop_sharedlock(ap)
           struct vop_lock_args /* {
                   struct vnode *a_vp;
                   int a_flags;
                   struct proc *a_p;
           } */ *ap;
   {
           /*
            * This code cannot be used until all the non-locking filesystems
            * (notably NFS) are converted to properly lock and release nodes.
            * Also, certain vnode operations change the locking state within
            * the operation (create, mknod, remove, link, rename, mkdir, rmdir,
            * and symlink). Ideally these operations should not change the
            * lock state, but should be changed to let the caller of the
            * function unlock them. Otherwise all intermediate vnode layers
            * (such as union, umapfs, etc) must catch these functions to do
            * the necessary locking at their layer. Note that the inactive
            * and lookup operations also change their lock state, but this 
            * cannot be avoided, so these two operations will always need
            * to be handled in intermediate layers.
            */
           struct vnode *vp = ap->a_vp;
           struct lock *l = (struct lock *)vp->v_data;
           int vnflags, flags = ap->a_flags;
   
           if (l == NULL) {
                   if (ap->a_flags & LK_INTERLOCK)
                           simple_unlock(&ap->a_vp->v_interlock);
                   return 0;
           }
           switch (flags & LK_TYPE_MASK) {
           case LK_DRAIN:
                   vnflags = LK_DRAIN;
                   break;
           case LK_EXCLUSIVE:
   #ifdef DEBUG_VFS_LOCKS
                   /*
                    * Normally, we use shared locks here, but that confuses
                    * the locking assertions.
                    */
                   vnflags = LK_EXCLUSIVE;
                   break;
   #endif
           case LK_SHARED:
                   vnflags = LK_SHARED;
                   break;
           case LK_UPGRADE:
           case LK_EXCLUPGRADE:
           case LK_DOWNGRADE:
                   return (0);
           case LK_RELEASE:
           default:
                   panic("vop_sharedlock: bad operation %d", flags & LK_TYPE_MASK);
           }
           if (flags & LK_INTERLOCK)
                   vnflags |= LK_INTERLOCK;
   #ifndef DEBUG_LOCKS
           return (lockmgr(l, vnflags, &vp->v_interlock, ap->a_p));
   #else
           return (debuglockmgr(l, vnflags, &vp->v_interlock, ap->a_p,
               "vop_sharedlock", vp->filename, vp->line));
   #endif
   }
   
   /*
    * Stubs to use when there is no locking to be done on the underlying object.
    * A minimal shared lock is necessary to ensure that the underlying object
    * is not revoked while an operation is in progress. So, an active shared
    * count is maintained in an auxillary vnode lock structure.
    */
   int
   vop_nolock(ap)
           struct vop_lock_args /* {
                   struct vnode *a_vp;
                   int a_flags;
                   struct proc *a_p;
           } */ *ap;
   {
   #ifdef notyet
           /*
            * This code cannot be used until all the non-locking filesystems
            * (notably NFS) are converted to properly lock and release nodes.
            * Also, certain vnode operations change the locking state within
            * the operation (create, mknod, remove, link, rename, mkdir, rmdir,
            * and symlink). Ideally these operations should not change the
            * lock state, but should be changed to let the caller of the
            * function unlock them. Otherwise all intermediate vnode layers
            * (such as union, umapfs, etc) must catch these functions to do
            * the necessary locking at their layer. Note that the inactive
            * and lookup operations also change their lock state, but this 
            * cannot be avoided, so these two operations will always need
            * to be handled in intermediate layers.
            */
           struct vnode *vp = ap->a_vp;
           int vnflags, flags = ap->a_flags;
   
           switch (flags & LK_TYPE_MASK) {
           case LK_DRAIN:
                   vnflags = LK_DRAIN;
                   break;
           case LK_EXCLUSIVE:
           case LK_SHARED:
                   vnflags = LK_SHARED;
                   break;
           case LK_UPGRADE:
           case LK_EXCLUPGRADE:
           case LK_DOWNGRADE:
                   return (0);
           case LK_RELEASE:
           default:
                   panic("vop_nolock: bad operation %d", flags & LK_TYPE_MASK);
           }
           if (flags & LK_INTERLOCK)
                   vnflags |= LK_INTERLOCK;
           return(lockmgr(vp->v_vnlock, vnflags, &vp->v_interlock, ap->a_p));
   #else /* for now */
           /*
            * Since we are not using the lock manager, we must clear
            * the interlock here.
            */
           if (ap->a_flags & LK_INTERLOCK)
                   simple_unlock(&ap->a_vp->v_interlock);
           return (0);
   #endif
   }
   
   /*
    * Do the inverse of vop_nolock, handling the interlock in a compatible way.
    */
   int
   vop_nounlock(ap)
           struct vop_unlock_args /* {
                   struct vnode *a_vp;
                   int a_flags;
                   struct proc *a_p;
           } */ *ap;
   {
           if (ap->a_flags & LK_INTERLOCK)
                   simple_unlock(&ap->a_vp->v_interlock);
           return (0);
   }
   
   /*
    * Return whether or not the node is in use.
    */
   int
   vop_noislocked(ap)
           struct vop_islocked_args /* {
                   struct vnode *a_vp;
                   struct proc *a_p;
           } */ *ap;
   {
           return (0);
   }
   
   int
   vop_stdcreatevobject(ap)
           struct vop_createvobject_args /* {
                   struct vnode *vp;
                   struct ucred *cred;
                   struct proc *p;
           } */ *ap;
   {
           struct vnode *vp = ap->a_vp;
           struct ucred *cred = ap->a_cred;
           struct proc *p = ap->a_p;
           struct vattr vat;
           vm_object_t object;
           int error = 0;
   
           if (!vn_isdisk(vp, NULL) && vn_canvmio(vp) == FALSE)
                   return (0);
   
   retry:
           if ((object = vp->v_object) == NULL) {
                   if (vp->v_type == VREG || vp->v_type == VDIR) {
                           if ((error = VOP_GETATTR(vp, &vat, cred, p)) != 0)
                                   goto retn;
                           object = vnode_pager_alloc(vp, vat.va_size, 0, 0);
                   } else if (devsw(vp->v_rdev) != NULL) {
                           /*
                            * This simply allocates the biggest object possible
                            * for a disk vnode.  This should be fixed, but doesn't
                            * cause any problems (yet).
                            */
                           object = vnode_pager_alloc(vp, IDX_TO_OFF(INT_MAX), 0, 0);
                   } else {
                           goto retn;
                   }
                   /*
                    * Dereference the reference we just created.  This assumes
                    * that the object is associated with the vp.
                    */
                   object->ref_count--;
                   vp->v_usecount--;
           } else {
                   if (object->flags & OBJ_DEAD) {
                           VOP_UNLOCK(vp, 0, p);
                           tsleep(object, PVM, "vodead", 0);
                           vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
                           goto retry;
                   }
           }
   
           KASSERT(vp->v_object != NULL, ("vfs_object_create: NULL object"));
           vp->v_flag |= VOBJBUF;
   
   retn:
           return (error);
   }
   
   int
   vop_stddestroyvobject(ap)
           struct vop_destroyvobject_args /* {
                   struct vnode *vp;
           } */ *ap;
   {
           struct vnode *vp = ap->a_vp;
           vm_object_t obj = vp->v_object;
   
           if (vp->v_object == NULL)
                   return (0);
   
           if (obj->ref_count == 0) {
                   /*
                    * vclean() may be called twice. The first time
                    * removes the primary reference to the object,
                    * the second time goes one further and is a
                    * special-case to terminate the object.
                    *
                    * don't double-terminate the object.
                    */
                   if ((obj->flags & OBJ_DEAD) == 0)
                           vm_object_terminate(obj);
           } else {
                   /*
                    * Woe to the process that tries to page now :-).
                    */
                   vm_pager_deallocate(obj);
           }
           return (0);
   }
   
   /*
    * Return the underlying VM object.  This routine may be called with or
    * without the vnode interlock held.  If called without, the returned
    * object is not guarenteed to be valid.  The syncer typically gets the
    * object without holding the interlock in order to quickly test whether
    * it might be dirty before going heavy-weight.  vm_object's use zalloc
    * and thus stable-storage, so this is safe.
    */
   int
   vop_stdgetvobject(ap)
           struct vop_getvobject_args /* {
                   struct vnode *vp;
                   struct vm_object **objpp;
           } */ *ap;
   {
           struct vnode *vp = ap->a_vp;
           struct vm_object **objpp = ap->a_objpp;
   
           if (objpp)
                   *objpp = vp->v_object;
           return (vp->v_object ? 0 : EINVAL);
   }
   
   /* 
    * vfs default ops
    * used to fill the vfs fucntion table to get reasonable default return values.
    */
   int 
   vfs_stdmount (mp, path, data, ndp, p)
           struct mount *mp;
           char *path;
           caddr_t data; 
           struct nameidata *ndp;
           struct proc *p;
   {
           return (0);
   }
   
   int     
   vfs_stdunmount (mp, mntflags, p)
           struct mount *mp;
           int mntflags;
           struct proc *p;
   {
           return (0);
   }
   
   int     
   vfs_stdroot (mp, vpp)
           struct mount *mp;
           struct vnode **vpp;
   {
           return (EOPNOTSUPP);
   }
   
   int     
   vfs_stdstatfs (mp, sbp, p)
           struct mount *mp;
           struct statfs *sbp;
           struct proc *p;
   {
           return (EOPNOTSUPP);
   }
   
   int
   vfs_stdvptofh (vp, fhp)
           struct vnode *vp;
           struct fid *fhp;
   {
           return (EOPNOTSUPP);
   }
   
   int     
   vfs_stdstart (mp, flags, p)
           struct mount *mp;
           int flags;
           struct proc *p;
   {
           return (0);
   }
   
   int     
   vfs_stdquotactl (mp, cmds, uid, arg, p)
           struct mount *mp;
           int cmds;
           uid_t uid;
           caddr_t arg;
           struct proc *p;
   {
           return (EOPNOTSUPP);
   }
   
   int     
   vfs_stdsync (mp, waitfor, cred, p)
           struct mount *mp;
           int waitfor;
           struct ucred *cred; 
           struct proc *p;
   {
           return (0);
   }
   
   int     
   vfs_stdvget (mp, ino, vpp)
           struct mount *mp;
           ino_t ino;
           struct vnode **vpp;
   {
           return (EOPNOTSUPP);
   }
   
   int     
   vfs_stdfhtovp (mp, fhp, vpp)
           struct mount *mp;
           struct fid *fhp;
           struct vnode **vpp;
   {
           return (EOPNOTSUPP);
   }
   
   int 
   vfs_stdcheckexp (mp, nam, extflagsp, credanonp)
           struct mount *mp;
           struct sockaddr *nam;
           int *extflagsp;
           struct ucred **credanonp;
   {
           return (EOPNOTSUPP);
   }
   
   int
   vfs_stdinit (vfsp) 
           struct vfsconf *vfsp;
   {
           return (0);
   }
   
   int
   vfs_stduninit (vfsp)
           struct vfsconf *vfsp;
   {
           return(0);
   }
   
   int
   vfs_stdextattrctl(mp, cmd, attrname, arg, p)
           struct mount *mp;
           int cmd;
           const char *attrname;
           caddr_t arg;
           struct proc *p;
   {
           return(EOPNOTSUPP);
   }
   
   /* end of vfs default ops */

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