usr/src/sys/miscfs/umapfs/umap_subr.c

/*
 * Copyright (c) 1992 The Regents of the University of California
 * Copyright (c) 1990, 1992 Jan-Simon Pendry
 * All rights reserved.
 *
 * This code is derived from software donated to Berkeley by
 * Jan-Simon Pendry.
 *
 * %sccs.include.redist.c%
 *
 *      @(#)lofs_subr.c 1.2 (Berkeley) 6/18/92
 *
 * $Id: lofs_subr.c,v 1.11 1992/05/30 10:05:43 jsp Exp jsp $
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/malloc.h>
#include <umapfs/umap.h>

#define LOG2_SIZEVNODE 7                /* log2(sizeof struct vnode) */
#define NUMAPNODECACHE 16
#define UMAP_NHASH(vp) ((((u_long)vp)>>LOG2_SIZEVNODE) & (NUMAPNODECACHE-1))

/*
 * Null layer cache:
 * Each cache entry holds a reference to the target vnode
 * along with a pointer to the alias vnode.  When an
 * entry is added the target vnode is VREF'd.  When the
 * alias is removed the target vnode is vrele'd.
 */

/*
 * Cache head
 */
struct umap_node_cache {
        struct umap_node        *ac_forw;
        struct umap_node        *ac_back;
};

static struct umap_node_cache umap_node_cache[NUMAPNODECACHE];

/*
 * Initialise cache headers
 */
umapfs_init()
{
        struct umap_node_cache *ac;
#ifdef UMAPFS_DIAGNOSTIC
        printf("umapfs_init\n");                /* printed during system boot */
#endif

        for (ac = umap_node_cache; ac < umap_node_cache + NUMAPNODECACHE; ac++)
                ac->ac_forw = ac->ac_back = (struct umap_node *) ac;
}

/*
 * Compute hash list for given target vnode
 */
static struct umap_node_cache *
umap_node_hash(targetvp)
struct vnode *targetvp;
{
        return (&umap_node_cache[UMAP_NHASH(targetvp)]);
}

/*
 * Make a new umap_node node.
 * Vp is the alias vnode, lofsvp is the target vnode.
 * Maintain a reference to (targetvp).
 */
static void
umap_node_alloc(vp, targetvp)
        struct vnode *vp;
        struct vnode *targetvp;
{
        struct umap_node_cache *hd;
        struct umap_node *a;

#ifdef UMAPFS_DIAGNOSTIC
        printf("umap_node_alloc(%x, %x)\n", vp, targetvp);
#endif

        MALLOC(a, struct umap_node *, sizeof(struct umap_node), M_TEMP, M_WAITOK);
        vp->v_type = targetvp->v_type;
        a->umap_vnode = vp;
        vp->v_data = a;
        VREF(targetvp);   /* Extra VREF will be vrele'd in umap_node_create */
        a->umap_lowervp = targetvp;
        hd = umap_node_hash(targetvp);
        insque(a, hd);

#ifdef UMAPFS_DIAGNOSTIC
        vprint("umap_node_alloc vp", vp);
        vprint("umap_node_alloc targetvp", targetvp);
#endif
}

#ifdef UMAPFS_DIAGNOSTIC
/*
 * NEEDSWORK:  The ability to set lowervp to umap here
 * implies that one can never count on lowervp staying umap
 * (even if vp is locked).  This seems quite bad.  Think
 * about these things.
 */
void
umap_node_flushmp (mp)
        struct mount *mp;
{
        struct umap_node_cache *ac;
        int i = 0;
        struct umap_node *roota;

        printf("umap_node_flushmp (%x)\n", mp);

        roota = VTOUMAP(MOUNTTOUMAPMOUNT(mp)->umapm_rootvp);

        for (ac = umap_node_cache; ac < umap_node_cache + NUMAPNODECACHE; ac++) {
                struct umap_node *a = ac->ac_forw;
                while (a != (struct umap_node *) ac) {
                        if (a != roota && a->umap_vnode->v_mount == mp) {
                                struct vnode *vp = a->umap_lowervp;
                                if (vp) {
                                        a->umap_lowervp = 0;
                                        vprint("umap_flushmp: would vrele", vp);
                                        /*vrele(vp);*/
                                        i++;
                                }
                        }
                        a = a->umap_forw;
                }
        }
        if (i > 0)
                printf("umap_node: vrele'd %d aliases\n", i);
}
#endif

/*
 * Return alias for target vnode if already exists, else 0.
 */
static struct umap_node *
umap_node_find(mp, targetvp)
        struct mount *mp;
        struct vnode *targetvp;
{
        struct umap_node_cache *hd;
        struct umap_node *a;

#ifdef UMAPFS_DIAGNOSTIC
        printf("umap_node_find(mp = %x, target = %x)\n", mp, targetvp);
#endif

        /*
         * Find hash base, and then search the (two-way) linked
         * list looking for a umap_node structure which is referencing
         * the target vnode.  If found, the increment the umap_node
         * reference count (but NOT the target vnode's VREF counter).
         */
        hd = umap_node_hash(targetvp);

        for (a = hd->ac_forw; a != (struct umap_node *) hd; a = a->umap_forw) {
                if (a->umap_lowervp == targetvp && a->umap_vnode->v_mount == mp) {
#ifdef UMAPFS_DIAGNOSTIC
                        printf("umap_node_find(%x): found (%x,%x)->%x\n",
                                targetvp, mp, a->umap_vnode, targetvp);
#endif
                        return (a);
                }
        }

#ifdef UMAPFS_DIAGNOSTIC
        printf("umap_node_find(%x, %x): NOT found\n", mp, targetvp);
#endif

        return (0);
}

/*
 * Try to find an existing umap_node vnode refering
 * to it, otherwise make a new umap_node vnode which
 * contains a reference to the target vnode.
 */
int
umap_node_create(mp, targetvp, newvpp)
        struct mount *mp;
        struct vnode *targetvp;
        struct vnode **newvpp;
{
        struct umap_node *ap;
        struct vnode *aliasvp;

        ap = umap_node_find(mp, targetvp);

        if (ap) {
                /*
                 * Take another reference to the alias vnode
                 */
#ifdef UMAPFS_DIAGNOSTIC
                vprint("umap_node_create: exists", ap->umap_vnode);
#endif
                aliasvp = ap->umap_vnode;
                VREF(aliasvp);
        } else {
                int error;

                /*
                 * Get new vnode.
                 */
#ifdef UMAPFS_DIAGNOSTIC
                printf("umap_node_create: create new alias vnode\n");
#endif
                if (error = getnewvnode(VT_UFS, mp, umap_vnodeop_p, &aliasvp))
                        return (error); /* XXX: VT_LOFS above */

                /*
                 * Make new vnode reference the umap_node.
                 */
                umap_node_alloc(aliasvp, targetvp);

                /*
                 * aliasvp is already VREF'd by getnewvnode()
                 */
        }

        vrele(targetvp);

#ifdef UMAPFS_DIAGNOSTIC
        vprint("umap_node_create: alias", aliasvp);
        vprint("umap_node_create: target", targetvp);
#endif

        *newvpp = aliasvp;
        return (0);
}
#ifdef UMAPFS_DIAGNOSTIC
int umap_checkvp_barrier = 1;
struct vnode *
umap_checkvp(vp, fil, lno)
        struct vnode *vp;
        char *fil;
        int lno;
{
        struct umap_node *a = VTOUMAP(vp);
#if 0
        /*
         * Can't do this check because vop_reclaim runs
         * with funny vop vector.
         */
        if (vp->v_op != umap_vnodeop_p) {
                printf ("umap_checkvp: on non-umap-node\n");
                while (umap_checkvp_barrier) /*WAIT*/ ;
                panic("umap_checkvp");
        };
#endif
        if (a->umap_lowervp == NULL) {
                /* Should never happen */
                int i; u_long *p;
                printf("vp = %x, ZERO ptr\n", vp);
                for (p = (u_long *) a, i = 0; i < 8; i++)
                        printf(" %x", p[i]);
                printf("\n");
                /* wait for debugger */
                while (umap_checkvp_barrier) /*WAIT*/ ;
                panic("umap_checkvp");
        }
        if (a->umap_lowervp->v_usecount < 1) {
                int i; u_long *p;
                printf("vp = %x, unref'ed lowervp\n", vp);
                for (p = (u_long *) a, i = 0; i < 8; i++)
                        printf(" %x", p[i]);
                printf("\n");
                /* wait for debugger */
                while (umap_checkvp_barrier) /*WAIT*/ ;
                panic ("umap with unref'ed lowervp");
        };
#if 0
        printf("umap %x/%d -> %x/%d [%s, %d]\n",
                a->umap_vnode, a->umap_vnode->v_usecount,
                a->umap_lowervp, a->umap_lowervp->v_usecount,
                fil, lno);
#endif
        return a->umap_lowervp;
}
#endif

/* umap_mapids maps all of the ids in a credential, both user and group. */

umap_mapids(credp,usermap,unentries,groupmap,gnentries)
        struct ucred *credp;
        int * usermap, groupmap;
        int unentries,gnentries;
{
        int i,gid,uid;

        /* Find uid entry in map */

        uid = umap_findid(credp->cr_uid,usermap,unentries);

        if (uid != -1) {
                credp->cr_ruid =
                credp->cr_uid =
                        (u_short)uid;
        } else
                credp->cr_ruid = credp->cr_uid = (u_short)NOBODY;

        /* Find gid entry in map */

        gid = umap_findid(credp->cr_gid,groupmap,gnentries);

        if (gid != -1) {
                credp->cr_rgid =
                credp->cr_gid =
                        (u_short)gid;
        } else
                credp->cr_rgid = credp->cr_gid = (u_short)NULLGROUP;

        /* Now we must map each of the set of groups in the cr_groups
                structure. */

        i = 0;
        while (credp->cr_groups[i] != 0)
        {
                gid = umap_findid(credp->cr_groups[i],groupmap,
                        gnentries);

                if (gid != -1)
                        credp->cr_groups[i++] = (u_short)gid;
                else
                        credp->cr_groups[i++] = (u_short)NULLGROUP;

        }
}

/* umap_findid is called by various routines in umap_vnodeops.c to
 * find a user or group id in a map.
 */

umap_findid(id,map,nentries)
        ushort id;
        int map[][2];
        int nentries;
{
        int i;

        /* Find uid entry in map */
        i = 0;
        while ((i<nentries) && ((u_short)(map[i][0] ) != id))
                i++;

        if ( i < nentries )
                return (map[i][1]);
        else
                return (-1);

}

/* umap_reverse_findid is called by umap_getattr() in umap_vnodeops.c to
 * find a user or group id in a map, in reverse.
 */

umap_reverse_findid(id,map,nentries)
        ushort id;
        int map[][2];
        int nentries;
{
        int i;

        /* Find uid entry in map */
        i = 0;
        while ((i<nentries) && ((u_short)(map[i][1] ) != id))
                i++;

        if ( i < nentries )
                return (map[i][0]);
        else
                return (-1);

}