xnu-344.32.tar.gz

[apple/xnu.git] / bsd / kern / ubc_subr.c

/*
 * Copyright (c) 1999-2002 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/* 
 *      File:   ubc_subr.c
 *      Author: Umesh Vaishampayan [umeshv@apple.com]
 *              05-Aug-1999     umeshv  Created.
 *
 *      Functions related to Unified Buffer cache.
 *
 * Caller of UBC functions MUST have a valid reference on the vnode.
 *
 */ 

#undef DIAGNOSTIC
#define DIAGNOSTIC 1

#include <sys/types.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/ubc.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/ubc.h>
#include <sys/ucred.h>
#include <sys/proc.h>
#include <sys/buf.h>

#include <mach/mach_types.h>
#include <mach/memory_object_types.h>

#include <kern/zalloc.h>

#if DIAGNOSTIC
#if defined(assert)
#undef assert()
#endif
#define assert(cond)    \
    ((void) ((cond) ? 0 : panic("%s:%d (%s)", __FILE__, __LINE__, # cond)))
#else
#include <kern/assert.h>
#endif /* DIAGNOSTIC */

struct zone     *ubc_info_zone;

/* lock for changes to struct UBC */
static __inline__ void
ubc_lock(struct vnode *vp)
{
        /* For now, just use the v_interlock */
        simple_lock(&vp->v_interlock);
}

/* unlock */
static __inline__ void
ubc_unlock(struct vnode *vp)
{
        /* For now, just use the v_interlock */
        simple_unlock(&vp->v_interlock);
}

/*
 * Serialize the requests to the VM
 * Returns:
 *              0       -       Failure
 *              1       -       Sucessful in acquiring the lock
 *              2       -       Sucessful in acquiring the lock recursively
 *                              do not call ubc_unbusy()
 *                              [This is strange, but saves 4 bytes in struct ubc_info]
 */
static int
ubc_busy(struct vnode *vp)
{
        register struct ubc_info        *uip;

        if (!UBCINFOEXISTS(vp))
                return (0);

        uip = vp->v_ubcinfo;

        while (ISSET(uip->ui_flags, UI_BUSY)) {

                if (uip->ui_owner == (void *)current_thread())
                        return (2);

                SET(uip->ui_flags, UI_WANTED);
                (void) tsleep((caddr_t)&vp->v_ubcinfo, PINOD, "ubcbusy", 0);

                if (!UBCINFOEXISTS(vp))
                        return (0);
        }
        uip->ui_owner = (void *)current_thread();

        SET(uip->ui_flags, UI_BUSY);

        return (1);
}

static void
ubc_unbusy(struct vnode *vp)
{
        register struct ubc_info        *uip;

        if (!UBCINFOEXISTS(vp)) {
                wakeup((caddr_t)&vp->v_ubcinfo);
                return;
        }
        uip = vp->v_ubcinfo;
        CLR(uip->ui_flags, UI_BUSY);
        uip->ui_owner = (void *)NULL;

        if (ISSET(uip->ui_flags, UI_WANTED)) {
                CLR(uip->ui_flags, UI_WANTED);
                wakeup((caddr_t)&vp->v_ubcinfo);
        }
}

/*
 *      Initialization of the zone for Unified Buffer Cache.
 */
__private_extern__ void
ubc_init()
{
        int     i;

        i = (vm_size_t) sizeof (struct ubc_info);
        /* XXX  the number of elements should be tied in to maxvnodes */
        ubc_info_zone = zinit (i, 10000*i, 8192, "ubc_info zone");
        return;
}

/*
 *      Initialize a ubc_info structure for a vnode.
 */
int
ubc_info_init(struct vnode *vp)
{
        register struct ubc_info        *uip;
        void *  pager;
        struct vattr    vattr;
        struct proc *p = current_proc();
        int error = 0;
        kern_return_t kret;
        memory_object_control_t control;

        if (!UBCISVALID(vp))
                return (EINVAL);

        ubc_lock(vp);
        if (ISSET(vp->v_flag,  VUINIT)) {
                /*
                 * other thread is already doing this
                 * wait till done
                 */
                while (ISSET(vp->v_flag,  VUINIT)) {
                        SET(vp->v_flag, VUWANT); /* XXX overloaded! */
                        ubc_unlock(vp);
                        (void) tsleep((caddr_t)vp, PINOD, "ubcinfo", 0);
                        ubc_lock(vp);
                }
                ubc_unlock(vp);
                return (0);
        } else {
                SET(vp->v_flag, VUINIT);
        }

        uip = vp->v_ubcinfo;
        if ((uip == UBC_INFO_NULL) || (uip == UBC_NOINFO)) {
                ubc_unlock(vp);
                uip = (struct ubc_info *) zalloc(ubc_info_zone);
                uip->ui_pager = MEMORY_OBJECT_NULL;
                uip->ui_control = MEMORY_OBJECT_CONTROL_NULL;
                uip->ui_flags = UI_INITED;
                uip->ui_vnode = vp;
                uip->ui_ucred = NOCRED;
                uip->ui_refcount = 1;
                uip->ui_size = 0;
                uip->ui_mapped = 0;
                uip->ui_owner = (void *)NULL;
                ubc_lock(vp);
        }
#if DIAGNOSTIC
        else
                Debugger("ubc_info_init: already");
#endif /* DIAGNOSTIC */
        
        assert(uip->ui_flags != UI_NONE);
        assert(uip->ui_vnode == vp);

#if 0
        if(ISSET(uip->ui_flags, UI_HASPAGER))
                goto done;
#endif /* 0 */

        /* now set this ubc_info in the vnode */
        vp->v_ubcinfo = uip;
        SET(uip->ui_flags, UI_HASPAGER);
        ubc_unlock(vp);
        pager = (void *)vnode_pager_setup(vp, uip->ui_pager);
        assert(pager);
        ubc_setpager(vp, pager);

        /*
         * Note: We can not use VOP_GETATTR() to get accurate
         * value of ui_size. Thanks to NFS.
         * nfs_getattr() can call vinvalbuf() and in this case
         * ubc_info is not set up to deal with that.
         * So use bogus size.
         */

        /*
         * create a vnode - vm_object association
         * memory_object_create_named() creates a "named" reference on the
         * memory object we hold this reference as long as the vnode is
         * "alive."  Since memory_object_create_named() took its own reference
         * on the vnode pager we passed it, we can drop the reference
         * vnode_pager_setup() returned here.
         */
        kret = memory_object_create_named(pager,
                (memory_object_size_t)uip->ui_size, &control);
        vnode_pager_deallocate(pager); 
        if (kret != KERN_SUCCESS)
                panic("ubc_info_init: memory_object_create_named returned %d", kret);

        assert(control);
        uip->ui_control = control;      /* cache the value of the mo control */
        SET(uip->ui_flags, UI_HASOBJREF);       /* with a named reference */
        /* create a pager reference on the vnode */
        error = vnode_pager_vget(vp);
        if (error)
                panic("ubc_info_init: vnode_pager_vget error = %d", error);

        /* initialize the size */
        error = VOP_GETATTR(vp, &vattr, p->p_ucred, p);

        ubc_lock(vp);
        uip->ui_size = (error ? 0: vattr.va_size);

done:
        CLR(vp->v_flag, VUINIT);
        if (ISSET(vp->v_flag, VUWANT)) {
                CLR(vp->v_flag, VUWANT);
                ubc_unlock(vp);
                wakeup((caddr_t)vp);
        } else 
                ubc_unlock(vp);

        return (error);
}

/* Free the ubc_info */
static void
ubc_info_free(struct ubc_info *uip)
{
        struct ucred *credp;
        
        credp = uip->ui_ucred;
        if (credp != NOCRED) {
                uip->ui_ucred = NOCRED;
                crfree(credp);
        }

        if (uip->ui_control != MEMORY_OBJECT_CONTROL_NULL)
                memory_object_control_deallocate(uip->ui_control);

        zfree(ubc_info_zone, (vm_offset_t)uip);
        return;
}

void
ubc_info_deallocate(struct ubc_info *uip)
{

        assert(uip->ui_refcount > 0);

    if (uip->ui_refcount-- == 1) {
                struct vnode *vp;

                vp = uip->ui_vnode;
                if (ISSET(uip->ui_flags, UI_WANTED)) {
                        CLR(uip->ui_flags, UI_WANTED);
                        wakeup((caddr_t)&vp->v_ubcinfo);
                }

                ubc_info_free(uip);
        }
}

/*
 * Communicate with VM the size change of the file
 * returns 1 on success, 0 on failure
 */
int
ubc_setsize(struct vnode *vp, off_t nsize)
{
        off_t osize;    /* ui_size before change */
        off_t lastpg, olastpgend, lastoff;
        struct ubc_info *uip;
        memory_object_control_t control;
        kern_return_t kret;

        assert(nsize >= (off_t)0);

        if (UBCINVALID(vp))
                return (0);

        if (!UBCINFOEXISTS(vp))
                return (0);

        uip = vp->v_ubcinfo;
        osize = uip->ui_size;   /* call ubc_getsize() ??? */
        /* Update the size before flushing the VM */
        uip->ui_size = nsize;

        if (nsize >= osize)     /* Nothing more to do */
                return (1);             /* return success */

        /*
         * When the file shrinks, invalidate the pages beyond the
         * new size. Also get rid of garbage beyond nsize on the
         * last page. The ui_size already has the nsize. This
         * insures that the pageout would not write beyond the new
         * end of the file.
         */

        lastpg = trunc_page_64(nsize);
        olastpgend = round_page_64(osize);
        control = uip->ui_control;
        assert(control);
        lastoff = (nsize & PAGE_MASK_64);

        /*
         * If length is multiple of page size, we should not flush
         * invalidating is sufficient
         */
         if (!lastoff) {
        /* invalidate last page and old contents beyond nsize */
        kret = memory_object_lock_request(control,
                    (memory_object_offset_t)lastpg,
                    (memory_object_size_t)(olastpgend - lastpg),
                    MEMORY_OBJECT_RETURN_NONE, MEMORY_OBJECT_DATA_FLUSH,
                    VM_PROT_NO_CHANGE);
        if (kret != KERN_SUCCESS)
            printf("ubc_setsize: invalidate failed (error = %d)\n", kret);

                return ((kret == KERN_SUCCESS) ? 1 : 0);
         }

        /* flush the last page */
        kret = memory_object_lock_request(control,
                                (memory_object_offset_t)lastpg,
                                PAGE_SIZE_64,
                                MEMORY_OBJECT_RETURN_DIRTY, FALSE,
                                VM_PROT_NO_CHANGE);

        if (kret == KERN_SUCCESS) {
                /* invalidate last page and old contents beyond nsize */
                kret = memory_object_lock_request(control,
                                        (memory_object_offset_t)lastpg,
                                        (memory_object_size_t)(olastpgend - lastpg),
                                        MEMORY_OBJECT_RETURN_NONE, MEMORY_OBJECT_DATA_FLUSH,
                                        VM_PROT_NO_CHANGE);
                if (kret != KERN_SUCCESS)
                        printf("ubc_setsize: invalidate failed (error = %d)\n", kret);
        } else
                printf("ubc_setsize: flush failed (error = %d)\n", kret);

        return ((kret == KERN_SUCCESS) ? 1 : 0);
}

/*
 * Get the size of the file
 */
off_t
ubc_getsize(struct vnode *vp)
{
        return (vp->v_ubcinfo->ui_size);
}

/*
 * Caller indicate that the object corresponding to the vnode 
 * can not be cached in object cache. Make it so.
 * returns 1 on success, 0 on failure
 */
int
ubc_uncache(struct vnode *vp)
{
        kern_return_t kret;
        struct ubc_info *uip;
        int    recursed;
        memory_object_control_t control;
        memory_object_perf_info_data_t   perf;

        if (!UBCINFOEXISTS(vp))
                return (0);

        if ((recursed = ubc_busy(vp)) == 0)
                return (0);

        uip = vp->v_ubcinfo;

        assert(uip != UBC_INFO_NULL);

        /*
         * AGE it so that vfree() can make sure that it
         * would get recycled soon after the last reference is gone
         * This will insure that .nfs turds would not linger
         */
        vagevp(vp);

        /* set the "do not cache" bit */
        SET(uip->ui_flags, UI_DONTCACHE);

        control = uip->ui_control;
        assert(control);

        perf.cluster_size = PAGE_SIZE; /* XXX use real cluster_size. */
        perf.may_cache = FALSE;
        kret = memory_object_change_attributes(control,
                                MEMORY_OBJECT_PERFORMANCE_INFO,
                                (memory_object_info_t) &perf,
                                MEMORY_OBJECT_PERF_INFO_COUNT);

        if (kret != KERN_SUCCESS) {
                printf("ubc_uncache: memory_object_change_attributes_named "
                        "kret = %d", kret);
                if (recursed == 1)
                        ubc_unbusy(vp);
                return (0);
        }

        ubc_release_named(vp);

        if (recursed == 1)
                ubc_unbusy(vp);
        return (1);
}

/*
 * call ubc_clean() and ubc_uncache() on all the vnodes
 * for this mount point.
 * returns 1 on success, 0 on failure
 */
__private_extern__ int
ubc_umount(struct mount *mp)
{
        struct proc *p = current_proc();
        struct vnode *vp, *nvp;
        int ret = 1;

loop:
        simple_lock(&mntvnode_slock);
        for (vp = mp->mnt_vnodelist.lh_first; vp; vp = nvp) {
                if (vp->v_mount != mp) {
                        simple_unlock(&mntvnode_slock);
                        goto loop;
                }
                nvp = vp->v_mntvnodes.le_next;
                simple_unlock(&mntvnode_slock);
                if (UBCINFOEXISTS(vp)) {

                        /*
                         * Must get a valid reference on the vnode
                         * before callig UBC functions
                         */
                        if (vget(vp, 0, p)) {
                                ret = 0;
                                simple_lock(&mntvnode_slock);
                                continue; /* move on to the next vnode */
                        }
                        ret &= ubc_clean(vp, 0); /* do not invalidate */
                        ret &= ubc_uncache(vp);
                        vrele(vp);
                }
                simple_lock(&mntvnode_slock);
        }
        simple_unlock(&mntvnode_slock);
        return (ret);
}

/*
 * Call ubc_unmount() for all filesystems.
 * The list is traversed in reverse order
 * of mounting to avoid dependencies.
 */
__private_extern__ void
ubc_unmountall()
{
        struct mount *mp, *nmp;

        /*
         * Since this only runs when rebooting, it is not interlocked.
         */
        for (mp = mountlist.cqh_last; mp != (void *)&mountlist; mp = nmp) {
                nmp = mp->mnt_list.cqe_prev;
                (void) ubc_umount(mp);
        }
}

/* Get the credentials */
struct ucred *
ubc_getcred(struct vnode *vp)
{
        struct ubc_info *uip;

        uip = vp->v_ubcinfo;

        if (UBCINVALID(vp))
                return (NOCRED);

        return (uip->ui_ucred);
}

/*
 * Set the credentials
 * existing credentials are not changed
 * returns 1 on success and 0 on failure
 */
int
ubc_setcred(struct vnode *vp, struct proc *p)
{
        struct ubc_info *uip;
        struct ucred *credp;

        uip = vp->v_ubcinfo;

        if (UBCINVALID(vp))
                return (0); 

        credp = uip->ui_ucred;
        if (credp == NOCRED) {
                crhold(p->p_ucred);
                uip->ui_ucred = p->p_ucred;
        } 

        return (1);
}

/* Get the pager */
__private_extern__ memory_object_t
ubc_getpager(struct vnode *vp)
{
        struct ubc_info *uip;

        uip = vp->v_ubcinfo;

        if (UBCINVALID(vp))
                return (0);

        return (uip->ui_pager);
}

/*
 * Get the memory object associated with this vnode
 * If the vnode was reactivated, memory object would not exist.
 * Unless "do not rectivate" was specified, look it up using the pager.
 * If hold was requested create an object reference of one does not
 * exist already.
 */

memory_object_control_t
ubc_getobject(struct vnode *vp, int flags)
{
        struct ubc_info *uip;
        int    recursed;
        memory_object_control_t control;

        if (UBCINVALID(vp))
                return (0);

        if ((recursed = ubc_busy(vp)) == 0)
                return (0);

        uip = vp->v_ubcinfo;
        control = uip->ui_control;

        if ((flags & UBC_HOLDOBJECT) && (!ISSET(uip->ui_flags, UI_HASOBJREF))) {

                /*
                 * Take a temporary reference on the ubc info so that it won't go
                 * away during our recovery attempt.
                 */
                ubc_lock(vp);
                uip->ui_refcount++;
                ubc_unlock(vp);
                if (memory_object_recover_named(control, TRUE) == KERN_SUCCESS) {
                        SET(uip->ui_flags, UI_HASOBJREF);
                } else {
                        control = MEMORY_OBJECT_CONTROL_NULL;
                }
                if (recursed == 1)
                        ubc_unbusy(vp);
                ubc_info_deallocate(uip);

        } else {
                if (recursed == 1)
                        ubc_unbusy(vp);
        }

        return (control);
}

/* Set the pager */
int
ubc_setpager(struct vnode *vp, memory_object_t pager)
{
        struct ubc_info *uip;

        uip = vp->v_ubcinfo;

        if (UBCINVALID(vp))
                return (0);

        uip->ui_pager = pager;
        return (1);
}

int 
ubc_setflags(struct vnode * vp, int  flags)
{
        struct ubc_info *uip;

        if (UBCINVALID(vp))
                return (0);

        uip = vp->v_ubcinfo;

        SET(uip->ui_flags, flags);

        return (1);     
} 

int 
ubc_clearflags(struct vnode * vp, int  flags)
{
        struct ubc_info *uip;

        if (UBCINVALID(vp))
                return (0);

        uip = vp->v_ubcinfo;

        CLR(uip->ui_flags, flags);

        return (1);     
} 


int 
ubc_issetflags(struct vnode * vp, int  flags)
{
        struct ubc_info *uip;

        if (UBCINVALID(vp))
                return (0);

        uip = vp->v_ubcinfo;

        return (ISSET(uip->ui_flags, flags));
} 

off_t
ubc_blktooff(struct vnode *vp, daddr_t blkno)
{
        off_t file_offset;
        int error;

    if (UBCINVALID(vp))
        return ((off_t)-1);

        error = VOP_BLKTOOFF(vp, blkno, &file_offset);
        if (error)
                file_offset = -1;

        return (file_offset);
}

daddr_t
ubc_offtoblk(struct vnode *vp, off_t offset)
{
        daddr_t blkno;
        int error = 0;

    if (UBCINVALID(vp)) { 
        return ((daddr_t)-1);
    }   

        error = VOP_OFFTOBLK(vp, offset, &blkno);
        if (error)
                blkno = -1;

        return (blkno);
}

/*
 * Cause the file data in VM to be pushed out to the storage
 * it also causes all currently valid pages to be released
 * returns 1 on success, 0 on failure
 */
int
ubc_clean(struct vnode *vp, int invalidate)
{
        off_t size;
        struct ubc_info *uip;
        memory_object_control_t control;
        kern_return_t kret;
        int flags = 0;

        if (UBCINVALID(vp))
                return (0);

        if (!UBCINFOEXISTS(vp))
                return (0);

        /*
         * if invalidate was requested, write dirty data and then discard
         * the resident pages
         */
        if (invalidate)
                flags = (MEMORY_OBJECT_DATA_FLUSH | MEMORY_OBJECT_DATA_NO_CHANGE);

        uip = vp->v_ubcinfo;
        size = uip->ui_size;    /* call ubc_getsize() ??? */

        control = uip->ui_control;
        assert(control);

        vp->v_flag &= ~VHASDIRTY;
        vp->v_clen = 0;

        /* Write the dirty data in the file and discard cached pages */
        kret = memory_object_lock_request(control,
                                (memory_object_offset_t)0,
                                (memory_object_size_t)round_page_64(size),
                                MEMORY_OBJECT_RETURN_ALL, flags,
                                VM_PROT_NO_CHANGE);

        if (kret != KERN_SUCCESS)
                printf("ubc_clean: clean failed (error = %d)\n", kret);

        return ((kret == KERN_SUCCESS) ? 1 : 0);
}

/*
 * Cause the file data in VM to be pushed out to the storage
 * currently valid pages are NOT invalidated
 * returns 1 on success, 0 on failure
 */
int
ubc_pushdirty(struct vnode *vp)
{
        off_t size;
        struct ubc_info *uip;
        memory_object_control_t control;
        kern_return_t kret;

        if (UBCINVALID(vp))
                return (0);

        if (!UBCINFOEXISTS(vp))
                return (0);

        uip = vp->v_ubcinfo;
        size = uip->ui_size;    /* call ubc_getsize() ??? */

        control = uip->ui_control;
        assert(control);

        vp->v_flag &= ~VHASDIRTY;
        vp->v_clen = 0;

        /* Write the dirty data in the file and discard cached pages */
        kret = memory_object_lock_request(control,
                                (memory_object_offset_t)0,
                                (memory_object_size_t)round_page_64(size),
                                MEMORY_OBJECT_RETURN_DIRTY, FALSE,
                                VM_PROT_NO_CHANGE);

        if (kret != KERN_SUCCESS)
                printf("ubc_pushdirty: flush failed (error = %d)\n", kret);

        return ((kret == KERN_SUCCESS) ? 1 : 0);
}

/*
 * Cause the file data in VM to be pushed out to the storage
 * currently valid pages are NOT invalidated
 * returns 1 on success, 0 on failure
 */
int
ubc_pushdirty_range(struct vnode *vp, off_t offset, off_t size)
{
        struct ubc_info *uip;
        memory_object_control_t control;
        kern_return_t kret;

        if (UBCINVALID(vp))
                return (0);

        if (!UBCINFOEXISTS(vp))
                return (0);

        uip = vp->v_ubcinfo;

        control = uip->ui_control;
        assert(control);

        /* Write any dirty pages in the requested range of the file: */
        kret = memory_object_lock_request(control,
                                (memory_object_offset_t)offset,
                                (memory_object_size_t)round_page_64(size),
                                MEMORY_OBJECT_RETURN_DIRTY, FALSE,
                                VM_PROT_NO_CHANGE);

        if (kret != KERN_SUCCESS)
                printf("ubc_pushdirty_range: flush failed (error = %d)\n", kret);

        return ((kret == KERN_SUCCESS) ? 1 : 0);
}

/*
 * Make sure the vm object does not vanish 
 * returns 1 if the hold count was incremented
 * returns 0 if the hold count was not incremented
 * This return value should be used to balance 
 * ubc_hold() and ubc_rele().
 */
int
ubc_hold(struct vnode *vp)
{
        struct ubc_info *uip;
        int    recursed;
        memory_object_control_t object;

        if (UBCINVALID(vp))
                return (0);

        if ((recursed = ubc_busy(vp)) == 0) {
                /* must be invalid or dying vnode */
                assert(UBCINVALID(vp) ||
                        ((vp->v_flag & VXLOCK) || (vp->v_flag & VTERMINATE)));
                return (0);
        }

        uip = vp->v_ubcinfo;
        assert(uip->ui_control != MEMORY_OBJECT_CONTROL_NULL);

        ubc_lock(vp);
        uip->ui_refcount++;
        ubc_unlock(vp);

        if (!ISSET(uip->ui_flags, UI_HASOBJREF)) {
                if (memory_object_recover_named(uip->ui_control, TRUE)
                        != KERN_SUCCESS) {
                        if (recursed == 1)
                                ubc_unbusy(vp);
                        ubc_info_deallocate(uip);
                        return (0);
                }
                SET(uip->ui_flags, UI_HASOBJREF);
        }
        if (recursed == 1)
                ubc_unbusy(vp);

        assert(uip->ui_refcount > 0);

        return (1);
}

/*
 * Drop the holdcount.
 * release the reference on the vm object if the this is "uncached"
 * ubc_info.
 */
void
ubc_rele(struct vnode *vp)
{
        struct ubc_info *uip;

        if (UBCINVALID(vp))
                return;

        if (!UBCINFOEXISTS(vp)) {
                /* nothing more to do for a dying vnode */
                if ((vp->v_flag & VXLOCK) || (vp->v_flag & VTERMINATE))
                        return;
                panic("ubc_rele: can not");
        }

        uip = vp->v_ubcinfo;

        if (uip->ui_refcount == 1)
                panic("ubc_rele: ui_refcount");

        --uip->ui_refcount;

        if ((uip->ui_refcount == 1)
                && ISSET(uip->ui_flags, UI_DONTCACHE))
                (void) ubc_release_named(vp);

        return;
}

/*
 * The vnode is mapped explicitly, mark it so.
 */
__private_extern__ void
ubc_map(struct vnode *vp)
{
        struct ubc_info *uip;

        if (UBCINVALID(vp))
                return;

        if (!UBCINFOEXISTS(vp))
                return;

        ubc_lock(vp);
        uip = vp->v_ubcinfo;

        SET(uip->ui_flags, UI_WASMAPPED);
        uip->ui_mapped = 1;
        ubc_unlock(vp);

        return;
}

/*
 * Release the memory object reference on the vnode
 * only if it is not in use
 * Return 1 if the reference was released, 0 otherwise.
 */
int
ubc_release_named(struct vnode *vp)
{
        struct ubc_info *uip;
        int    recursed;
        memory_object_control_t control;
        kern_return_t kret = KERN_FAILURE;

        if (UBCINVALID(vp))
                return (0);

        if ((recursed = ubc_busy(vp)) == 0)
                return (0);
        uip = vp->v_ubcinfo;

        /* can not release held or mapped vnodes */
        if (ISSET(uip->ui_flags, UI_HASOBJREF) && 
                (uip->ui_refcount == 1) && !uip->ui_mapped) {
                control = uip->ui_control;
                assert(control);
                CLR(uip->ui_flags, UI_HASOBJREF);
                kret = memory_object_release_name(control,
                                MEMORY_OBJECT_RESPECT_CACHE);
        }

        if (recursed == 1)
                ubc_unbusy(vp);
        return ((kret != KERN_SUCCESS) ? 0 : 1);
}

/*
 * This function used to called by extensions directly.  Some may
 * still exist with this behavior.  In those cases, we will do the
 * release as part of reclaiming or cleaning the vnode.  We don't
 * need anything explicit - so just stub this out until those callers
 * get cleaned up.
 */
int
ubc_release(
        struct vnode    *vp)
{
        return 0;
}

/*
 * destroy the named reference for a given vnode
 */
__private_extern__ int
ubc_destroy_named(
        struct vnode    *vp)
{
        memory_object_control_t control;
        struct proc *p;
        struct ubc_info *uip;
        kern_return_t kret;

        /*
         * We may already have had the object terminated
         * and the ubcinfo released as a side effect of
         * some earlier processing.  If so, pretend we did
         * it, because it probably was a result of our
         * efforts.
         */
        if (!UBCINFOEXISTS(vp))
                return (1);

        uip = vp->v_ubcinfo;

        /* can not destroy held vnodes */
        if (uip->ui_refcount > 1)
                return (0);

        /* 
         * Terminate the memory object.
         * memory_object_destroy() will result in
         * vnode_pager_no_senders(). 
         * That will release the pager reference
         * and the vnode will move to the free list.
         */
        control = ubc_getobject(vp, UBC_HOLDOBJECT);
        if (control != MEMORY_OBJECT_CONTROL_NULL) {

                if (ISSET(vp->v_flag, VTERMINATE))
                        panic("ubc_destroy_named: already teminating");
                SET(vp->v_flag, VTERMINATE);

                kret = memory_object_destroy(control, 0);
                if (kret != KERN_SUCCESS)
                        return (0);

                /* 
                 * memory_object_destroy() is asynchronous
                 * with respect to vnode_pager_no_senders().
                 * wait for vnode_pager_no_senders() to clear
                 * VTERMINATE
                 */
                while (ISSET(vp->v_flag, VTERMINATE)) {
                        SET(vp->v_flag, VTERMWANT);
                        (void)tsleep((caddr_t)&vp->v_ubcinfo,
                                                 PINOD, "ubc_destroy_named", 0);
                }
        }
        return (1);
}


/*
 * Invalidate a range in the memory object that backs this
 * vnode. The offset is truncated to the page boundary and the
 * size is adjusted to include the last page in the range.
 */
int
ubc_invalidate(struct vnode *vp, off_t offset, size_t size)
{
        struct ubc_info *uip;
        memory_object_control_t control;
        kern_return_t kret;
        off_t toff;
        size_t tsize;

        if (UBCINVALID(vp))
                return (0);

        if (!UBCINFOEXISTS(vp))
                return (0);

        toff = trunc_page_64(offset);
        tsize = (size_t)(round_page_64(offset+size) - toff);
        uip = vp->v_ubcinfo;
        control = uip->ui_control;
        assert(control);

        /* invalidate pages in the range requested */
        kret = memory_object_lock_request(control,
                                (memory_object_offset_t)toff,
                                (memory_object_size_t)tsize,
                                MEMORY_OBJECT_RETURN_NONE,
                                (MEMORY_OBJECT_DATA_NO_CHANGE| MEMORY_OBJECT_DATA_FLUSH),
                                VM_PROT_NO_CHANGE);
        if (kret != KERN_SUCCESS)
                printf("ubc_invalidate: invalidate failed (error = %d)\n", kret);

        return ((kret == KERN_SUCCESS) ? 1 : 0);
}

/*
 * Find out whether a vnode is in use by UBC
 * Returns 1 if file is in use by UBC, 0 if not
 */
int
ubc_isinuse(struct vnode *vp, int tookref)
{
        int busycount = tookref ? 2 : 1;

        if (!UBCINFOEXISTS(vp))
                return (0);

        if (tookref == 0) {
                printf("ubc_isinuse: called without a valid reference"
                    ": v_tag = %d\v", vp->v_tag);
                vprint("ubc_isinuse", vp);
                return (0);
        }

        if (vp->v_usecount > busycount)
                return (1);

        if ((vp->v_usecount == busycount)
                && (vp->v_ubcinfo->ui_mapped == 1))
                return (1);
        else
                return (0);
}

/*
 * The backdoor routine to clear the ui_mapped.
 * MUST only be called by the VM
 *
 * Note that this routine is not called under funnel. There are numerous
 * things about the calling sequence that make this work on SMP.
 * Any code change in those paths can break this.
 *
 */
__private_extern__ void
ubc_unmap(struct vnode *vp)
{
        struct ubc_info *uip;
        boolean_t       funnel_state;
 
        if (UBCINVALID(vp))
                return;

        if (!UBCINFOEXISTS(vp))
                return;

        ubc_lock(vp);
        uip = vp->v_ubcinfo;
        uip->ui_mapped = 0;
        if ((uip->ui_refcount > 1) || !ISSET(uip->ui_flags, UI_DONTCACHE)) {
                ubc_unlock(vp);
                return;
        }
        ubc_unlock(vp);

        funnel_state = thread_funnel_set(kernel_flock, TRUE);
        (void) ubc_release_named(vp);
        (void) thread_funnel_set(kernel_flock, funnel_state);
}

kern_return_t
ubc_page_op(
        struct vnode    *vp,
        off_t           f_offset,
        int             ops,
        vm_offset_t     *phys_entryp,
        int             *flagsp)
{
        memory_object_control_t         control;

        control = ubc_getobject(vp, UBC_FLAGS_NONE);
        if (control == MEMORY_OBJECT_CONTROL_NULL)
                return KERN_INVALID_ARGUMENT;

        return (memory_object_page_op(control,
                                      (memory_object_offset_t)f_offset,
                                      ops,
                                      phys_entryp,
                                      flagsp));
}
                                      
kern_return_t
ubc_create_upl(
        struct vnode    *vp,
        off_t                   f_offset,
        long                    bufsize,
        upl_t                   *uplp,
        upl_page_info_t **plp,
        int                             uplflags)
{
        memory_object_control_t         control;
        int                                                     count;
        off_t                                           file_offset;
        kern_return_t                           kr;
        
        if (bufsize & 0xfff)
                return KERN_INVALID_ARGUMENT;

        control = ubc_getobject(vp, UBC_FLAGS_NONE);
        if (control == MEMORY_OBJECT_CONTROL_NULL)
                return KERN_INVALID_ARGUMENT;

        uplflags |= (UPL_NO_SYNC|UPL_CLEAN_IN_PLACE|UPL_SET_INTERNAL);
        count = 0;
        kr = memory_object_upl_request(control, f_offset, bufsize,
                                                                   uplp, NULL, &count, uplflags);
        if (plp != NULL)
                        *plp = UPL_GET_INTERNAL_PAGE_LIST(*uplp);
        return kr;
}
                                      

kern_return_t
ubc_upl_map(
        upl_t           upl,
        vm_offset_t     *dst_addr)
{
        return (vm_upl_map(kernel_map, upl, dst_addr));
}


kern_return_t
ubc_upl_unmap(
        upl_t   upl)
{
        return(vm_upl_unmap(kernel_map, upl));
}

kern_return_t
ubc_upl_commit(
        upl_t                   upl)
{
        upl_page_info_t *pl;
        kern_return_t   kr;

        pl = UPL_GET_INTERNAL_PAGE_LIST(upl);
        kr = upl_commit(upl, pl, MAX_UPL_TRANSFER);
        upl_deallocate(upl);
        return kr;
}


kern_return_t
ubc_upl_commit_range(
        upl_t                   upl,
        vm_offset_t             offset,
        vm_size_t               size,
        int                             flags)
{
        upl_page_info_t *pl;
        boolean_t               empty;
        kern_return_t   kr;

        if (flags & UPL_COMMIT_FREE_ON_EMPTY)
                flags |= UPL_COMMIT_NOTIFY_EMPTY;

        pl = UPL_GET_INTERNAL_PAGE_LIST(upl);

        kr = upl_commit_range(upl, offset, size, flags,
                                                  pl, MAX_UPL_TRANSFER, &empty);

        if((flags & UPL_COMMIT_FREE_ON_EMPTY) && empty)
                upl_deallocate(upl);

        return kr;
}
        
kern_return_t
ubc_upl_abort_range(
        upl_t                   upl,
        vm_offset_t             offset,
        vm_size_t               size,
        int                             abort_flags)
{
        kern_return_t   kr;
        boolean_t               empty = FALSE;

        if (abort_flags & UPL_ABORT_FREE_ON_EMPTY)
                abort_flags |= UPL_ABORT_NOTIFY_EMPTY;

        kr = upl_abort_range(upl, offset, size, abort_flags, &empty);

        if((abort_flags & UPL_ABORT_FREE_ON_EMPTY) && empty)
                upl_deallocate(upl);

        return kr;
}

kern_return_t
ubc_upl_abort(
        upl_t                   upl,
        int                             abort_type)
{
        kern_return_t   kr;

        kr = upl_abort(upl, abort_type);
        upl_deallocate(upl);
        return kr;
}

upl_page_info_t *
ubc_upl_pageinfo(
        upl_t                   upl)
{              
        return (UPL_GET_INTERNAL_PAGE_LIST(upl));
}