FreeBSD/Linux Kernel Cross Reference
sys/miscfs/umapfs/umap_vnops.c

     /*
      * Copyright (c) 1992, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * This code is derived from software donated to Berkeley by
      * the 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.
     *
     *      @(#)umap_vnops.c        8.6 (Berkeley) 5/22/95
     * $FreeBSD$
     */
    
    /*
     * Umap Layer
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/sysctl.h>
    #include <sys/vnode.h>
    #include <sys/mount.h>
    #include <sys/namei.h>
    #include <sys/malloc.h>
    #include <sys/buf.h>
    #include <miscfs/umapfs/umap.h>
    #include <miscfs/nullfs/null.h>
    
    static int umap_bug_bypass = 0;   /* for debugging: enables bypass printf'ing */
    SYSCTL_INT(_debug, OID_AUTO, umapfs_bug_bypass, CTLFLAG_RW,
            &umap_bug_bypass, 0, "");
    
    static int      umap_bwrite __P((struct vop_bwrite_args *ap));
    static int      umap_bypass __P((struct vop_generic_args *ap));
    static int      umap_getattr __P((struct vop_getattr_args *ap));
    static int      umap_inactive __P((struct vop_inactive_args *ap));
    static int      umap_lock __P((struct vop_lock_args *ap));
    static int      umap_print __P((struct vop_print_args *ap));
    static int      umap_reclaim __P((struct vop_reclaim_args *ap));
    static int      umap_rename __P((struct vop_rename_args *ap));
    static int      umap_strategy __P((struct vop_strategy_args *ap));
    static int      umap_unlock __P((struct vop_unlock_args *ap));
    
    /*
     * This is the 10-Apr-92 bypass routine.
     * See null_vnops.c:null_bypass for more details.
     */
    static int
    umap_bypass(ap)
            struct vop_generic_args /* {
                    struct vnodeop_desc *a_desc;
                    <other random data follows, presumably>
            } */ *ap;
    {
            struct ucred **credpp = 0, *credp = 0;
            struct ucred *savecredp = 0, *savecompcredp = 0;
            struct ucred *compcredp = 0;
            struct vnode **this_vp_p;
            int error;
            struct vnode *old_vps[VDESC_MAX_VPS];
            struct vnode *vp1 = 0;
            struct vnode **vps_p[VDESC_MAX_VPS];
            struct vnode ***vppp;
            struct vnodeop_desc *descp = ap->a_desc;
            int reles, i;
            struct componentname **compnamepp = 0;
    
            if (umap_bug_bypass)
                    printf ("umap_bypass: %s\n", descp->vdesc_name);
    
    #ifdef SAFETY
            /*
            * We require at least one vp.
            */
           if (descp->vdesc_vp_offsets == NULL ||
               descp->vdesc_vp_offsets[0] == VDESC_NO_OFFSET)
                   panic ("umap_bypass: no vp's in map.");
   #endif
   
           /*
            * Map the vnodes going in.
            * Later, we'll invoke the operation based on
            * the first mapped vnode's operation vector.
            */
           reles = descp->vdesc_flags;
           for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) {
                   if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET)
                           break;   /* bail out at end of list */
                   vps_p[i] = this_vp_p =
                           VOPARG_OFFSETTO(struct vnode**, descp->vdesc_vp_offsets[i], ap);
   
                   if (i == 0) {
                           vp1 = *vps_p[0];
                   }
   
                   /*
                    * We're not guaranteed that any but the first vnode
                    * are of our type.  Check for and don't map any
                    * that aren't.  (Must map first vp or vclean fails.)
                    */
   
                   if (i && (*this_vp_p)->v_op != umap_vnodeop_p) {
                           old_vps[i] = NULL;
                   } else {
                           old_vps[i] = *this_vp_p;
                           *(vps_p[i]) = UMAPVPTOLOWERVP(*this_vp_p);
                           if (reles & 1)
                                   VREF(*this_vp_p);
                   }
   
           }
   
           /*
            * Fix the credentials.  (That's the purpose of this layer.)
            */
   
           if (descp->vdesc_cred_offset != VDESC_NO_OFFSET) {
   
                   credpp = VOPARG_OFFSETTO(struct ucred**,
                       descp->vdesc_cred_offset, ap);
   
                   /* Save old values */
   
                   savecredp = (*credpp);
                   if (savecredp != NOCRED)
                           (*credpp) = crdup(savecredp);
                   credp = *credpp;
   
                   if (umap_bug_bypass && credp->cr_uid != 0)
                           printf("umap_bypass: user was %lu, group %lu\n",
                               (u_long)credp->cr_uid, (u_long)credp->cr_gid);
   
                   /* Map all ids in the credential structure. */
   
                   umap_mapids(vp1->v_mount, credp);
   
                   if (umap_bug_bypass && credp->cr_uid != 0)
                           printf("umap_bypass: user now %lu, group %lu\n",
                               (u_long)credp->cr_uid, (u_long)credp->cr_gid);
           }
   
           /* BSD often keeps a credential in the componentname structure
            * for speed.  If there is one, it better get mapped, too.
            */
   
           if (descp->vdesc_componentname_offset != VDESC_NO_OFFSET) {
   
                   compnamepp = VOPARG_OFFSETTO(struct componentname**,
                       descp->vdesc_componentname_offset, ap);
   
                   compcredp = (*compnamepp)->cn_cred;
                   savecompcredp = compcredp;
                   if (savecompcredp != NOCRED)
                           (*compnamepp)->cn_cred = crdup(savecompcredp);
                   compcredp = (*compnamepp)->cn_cred;
   
                   if (umap_bug_bypass && compcredp->cr_uid != 0)
                           printf(
                       "umap_bypass: component credit user was %lu, group %lu\n",
                               (u_long)compcredp->cr_uid,
                               (u_long)compcredp->cr_gid);
   
                   /* Map all ids in the credential structure. */
   
                   umap_mapids(vp1->v_mount, compcredp);
   
                   if (umap_bug_bypass && compcredp->cr_uid != 0)
                           printf(
                       "umap_bypass: component credit user now %lu, group %lu\n",
                               (u_long)compcredp->cr_uid,
                               (u_long)compcredp->cr_gid);
           }
   
           /*
            * Call the operation on the lower layer
            * with the modified argument structure.
            */
           error = VCALL(*(vps_p[0]), descp->vdesc_offset, ap);
   
           /*
            * Maintain the illusion of call-by-value
            * by restoring vnodes in the argument structure
            * to their original value.
            */
           reles = descp->vdesc_flags;
           for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) {
                   if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET)
                           break;   /* bail out at end of list */
                   if (old_vps[i]) {
                           *(vps_p[i]) = old_vps[i];
                           if (reles & 1)
                                   vrele(*(vps_p[i]));
                   };
           };
   
           /*
            * Map the possible out-going vpp
            * (Assumes that the lower layer always returns
            * a VREF'ed vpp unless it gets an error.)
            */
           if (descp->vdesc_vpp_offset != VDESC_NO_OFFSET &&
               !(descp->vdesc_flags & VDESC_NOMAP_VPP) &&
               !error) {
                   if (descp->vdesc_flags & VDESC_VPP_WILLRELE)
                           goto out;
                   vppp = VOPARG_OFFSETTO(struct vnode***,
                                    descp->vdesc_vpp_offset, ap);
                   if (*vppp)
                           error = umap_node_create(old_vps[0]->v_mount, **vppp, *vppp);
           };
   
    out:
           /*
            * Free duplicate cred structure and restore old one.
            */
           if (descp->vdesc_cred_offset != VDESC_NO_OFFSET) {
                   if (umap_bug_bypass && credp && credp->cr_uid != 0)
                           printf("umap_bypass: returning-user was %lu\n",
                               (u_long)credp->cr_uid);
   
                   if (savecredp != NOCRED) {
                           crfree(credp);
                           (*credpp) = savecredp;
                           if (umap_bug_bypass && credpp && (*credpp)->cr_uid != 0)
                                   printf(
                                       "umap_bypass: returning-user now %lu\n\n",
                                       (u_long)(*credpp)->cr_uid);
                   }
           }
   
           if (descp->vdesc_componentname_offset != VDESC_NO_OFFSET) {
                   if (umap_bug_bypass && compcredp && compcredp->cr_uid != 0)
                           printf(
                               "umap_bypass: returning-component-user was %lu\n",
                               (u_long)compcredp->cr_uid);
   
                   if (savecompcredp != NOCRED) {
                           crfree(compcredp);
                           (*compnamepp)->cn_cred = savecompcredp;
                           if (umap_bug_bypass && credpp && (*credpp)->cr_uid != 0)
                                   printf(
                               "umap_bypass: returning-component-user now %lu\n",
                                       (u_long)compcredp->cr_uid);
                   }
           }
   
           return (error);
   }
   
   
   /*
    *  We handle getattr to change the fsid.
    */
   static int
   umap_getattr(ap)
           struct vop_getattr_args /* {
                   struct vnode *a_vp;
                   struct vattr *a_vap;
                   struct ucred *a_cred;
                   struct proc *a_p;
           } */ *ap;
   {
           short uid, gid;
           int error, tmpid, nentries, gnentries;
           u_long (*mapdata)[2], (*gmapdata)[2];
           struct vnode **vp1p;
           struct vnodeop_desc *descp = ap->a_desc;
   
           error = umap_bypass((struct vop_generic_args *)ap);
           if (error)
                   return (error);
           /* Requires that arguments be restored. */
           ap->a_vap->va_fsid = ap->a_vp->v_mount->mnt_stat.f_fsid.val[0];
   
           /*
            * Umap needs to map the uid and gid returned by a stat
            * into the proper values for this site.  This involves
            * finding the returned uid in the mapping information,
            * translating it into the uid on the other end,
            * and filling in the proper field in the vattr
            * structure pointed to by ap->a_vap.  The group
            * is easier, since currently all groups will be
            * translate to the NULLGROUP.
            */
   
           /* Find entry in map */
   
           uid = ap->a_vap->va_uid;
           gid = ap->a_vap->va_gid;
           if (umap_bug_bypass)
                   printf("umap_getattr: mapped uid = %d, mapped gid = %d\n", uid,
                       gid);
   
           vp1p = VOPARG_OFFSETTO(struct vnode**, descp->vdesc_vp_offsets[0], ap);
           nentries =  MOUNTTOUMAPMOUNT((*vp1p)->v_mount)->info_nentries;
           mapdata =  (MOUNTTOUMAPMOUNT((*vp1p)->v_mount)->info_mapdata);
           gnentries =  MOUNTTOUMAPMOUNT((*vp1p)->v_mount)->info_gnentries;
           gmapdata =  (MOUNTTOUMAPMOUNT((*vp1p)->v_mount)->info_gmapdata);
   
           /* Reverse map the uid for the vnode.  Since it's a reverse
                   map, we can't use umap_mapids() to do it. */
   
           tmpid = umap_reverse_findid(uid, mapdata, nentries);
   
           if (tmpid != -1) {
   
                   ap->a_vap->va_uid = (uid_t) tmpid;
                   if (umap_bug_bypass)
                           printf("umap_getattr: original uid = %d\n", uid);
           } else
                   ap->a_vap->va_uid = (uid_t) NOBODY;
   
           /* Reverse map the gid for the vnode. */
   
           tmpid = umap_reverse_findid(gid, gmapdata, gnentries);
   
           if (tmpid != -1) {
   
                   ap->a_vap->va_gid = (gid_t) tmpid;
                   if (umap_bug_bypass)
                           printf("umap_getattr: original gid = %d\n", gid);
           } else
                   ap->a_vap->va_gid = (gid_t) NULLGROUP;
   
           return (0);
   }
   
   /*
    * We need to process our own vnode lock and then clear the
    * interlock flag as it applies only to our vnode, not the
    * vnodes below us on the stack.
    */
   static int
   umap_lock(ap)
           struct vop_lock_args /* {
                   struct vnode *a_vp;
                   int a_flags;
                   struct proc *a_p;
           } */ *ap;
   {
   
           vop_nolock(ap);
           if ((ap->a_flags & LK_TYPE_MASK) == LK_DRAIN)
                   return (0);
           ap->a_flags &= ~LK_INTERLOCK;
           return (null_bypass((struct vop_generic_args *)ap));
   }
   
   /*
    * We need to process our own vnode unlock and then clear the
    * interlock flag as it applies only to our vnode, not the
    * vnodes below us on the stack.
    */
   int
   umap_unlock(ap)
           struct vop_unlock_args /* {
                   struct vnode *a_vp;
                   int a_flags;
                   struct proc *a_p;
           } */ *ap;
   {
           vop_nounlock(ap);
           ap->a_flags &= ~LK_INTERLOCK;
           return (null_bypass((struct vop_generic_args *)ap));
   }
   
   static int
   umap_inactive(ap)
           struct vop_inactive_args /* {
                   struct vnode *a_vp;
                   struct proc *a_p;
           } */ *ap;
   {
           struct vnode *vp = ap->a_vp;
           struct umap_node *xp = VTOUMAP(vp);
           struct vnode *lowervp = xp->umap_lowervp;
           /*
            * Do nothing (and _don't_ bypass).
            * Wait to vrele lowervp until reclaim,
            * so that until then our umap_node is in the
            * cache and reusable.
            *
            */
           VOP_INACTIVE(lowervp, ap->a_p);
           VOP_UNLOCK(ap->a_vp, 0, ap->a_p);
           return (0);
   }
   
   static int
   umap_reclaim(ap)
           struct vop_reclaim_args /* {
                   struct vnode *a_vp;
           } */ *ap;
   {
           struct vnode *vp = ap->a_vp;
           struct umap_node *xp = VTOUMAP(vp);
           struct vnode *lowervp = xp->umap_lowervp;
   
           /* After this assignment, this node will not be re-used. */
           xp->umap_lowervp = NULL;
           LIST_REMOVE(xp, umap_hash);
           FREE(vp->v_data, M_TEMP);
           vp->v_data = NULL;
           vrele(lowervp);
           return (0);
   }
   
   static int
   umap_strategy(ap)
           struct vop_strategy_args /* {
                   struct vnode *a_vp;
                   struct buf *a_bp;
           } */ *ap;
   {
           struct buf *bp = ap->a_bp;
           int error;
           struct vnode *savedvp;
   
           savedvp = bp->b_vp;
           bp->b_vp = UMAPVPTOLOWERVP(bp->b_vp);
   
           error = VOP_STRATEGY(bp->b_vp, ap->a_bp);
   
           bp->b_vp = savedvp;
   
           return (error);
   }
   
   static int
   umap_bwrite(ap)
           struct vop_bwrite_args /* {
                   struct buf *a_bp;
           } */ *ap;
   {
           struct buf *bp = ap->a_bp;
           int error;
           struct vnode *savedvp;
   
           savedvp = bp->b_vp;
           bp->b_vp = UMAPVPTOLOWERVP(bp->b_vp);
   
           error = VOP_BWRITE(ap->a_bp);
   
           bp->b_vp = savedvp;
   
           return (error);
   }
   
   
   static int
   umap_print(ap)
           struct vop_print_args /* {
                   struct vnode *a_vp;
           } */ *ap;
   {
           struct vnode *vp = ap->a_vp;
           printf("\ttag VT_UMAPFS, vp=%p, lowervp=%p\n", vp, UMAPVPTOLOWERVP(vp));
           return (0);
   }
   
   static int
   umap_rename(ap)
           struct vop_rename_args  /* {
                   struct vnode *a_fdvp;
                   struct vnode *a_fvp;
                   struct componentname *a_fcnp;
                   struct vnode *a_tdvp;
                   struct vnode *a_tvp;
                   struct componentname *a_tcnp;
           } */ *ap;
   {
           int error;
           struct componentname *compnamep;
           struct ucred *compcredp, *savecompcredp;
           struct vnode *vp;
   
           /*
            * Rename is irregular, having two componentname structures.
            * We need to map the cre in the second structure,
            * and then bypass takes care of the rest.
            */
   
           vp = ap->a_fdvp;
           compnamep = ap->a_tcnp;
           compcredp = compnamep->cn_cred;
   
           savecompcredp = compcredp;
           compcredp = compnamep->cn_cred = crdup(savecompcredp);
   
           if (umap_bug_bypass && compcredp->cr_uid != 0)
                   printf(
               "umap_rename: rename component credit user was %lu, group %lu\n",
                       (u_long)compcredp->cr_uid, (u_long)compcredp->cr_gid);
   
           /* Map all ids in the credential structure. */
   
           umap_mapids(vp->v_mount, compcredp);
   
           if (umap_bug_bypass && compcredp->cr_uid != 0)
                   printf(
               "umap_rename: rename component credit user now %lu, group %lu\n",
                       (u_long)compcredp->cr_uid, (u_long)compcredp->cr_gid);
   
           error = umap_bypass((struct vop_generic_args *)ap);
   
           /* Restore the additional mapped componentname cred structure. */
   
           crfree(compcredp);
           compnamep->cn_cred = savecompcredp;
   
           return error;
   }
   
   /*
    * Global vfs data structures
    */
   /*
    * XXX - strategy, bwrite are hand coded currently.  They should
    * go away with a merged buffer/block cache.
    *
    */
   vop_t **umap_vnodeop_p;
   static struct vnodeopv_entry_desc umap_vnodeop_entries[] = {
           { &vop_default_desc,            (vop_t *) umap_bypass },
           { &vop_bwrite_desc,             (vop_t *) umap_bwrite },
           { &vop_getattr_desc,            (vop_t *) umap_getattr },
           { &vop_inactive_desc,           (vop_t *) umap_inactive },
           { &vop_lock_desc,               (vop_t *) umap_lock },
           { &vop_print_desc,              (vop_t *) umap_print },
           { &vop_reclaim_desc,            (vop_t *) umap_reclaim },
           { &vop_rename_desc,             (vop_t *) umap_rename },
           { &vop_strategy_desc,           (vop_t *) umap_strategy },
           { &vop_unlock_desc,             (vop_t *) umap_unlock },
           { NULL, NULL }
   };
   static struct vnodeopv_desc umap_vnodeop_opv_desc =
           { &umap_vnodeop_p, umap_vnodeop_entries };
   
   VNODEOP_SET(umap_vnodeop_opv_desc);

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