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freebsd/sys/vm/vnode_pager.c
David Greenman 24a1cce34f NOTE: libkvm, w, ps, 'top', and any other utility which depends on struct 
proc or any VM system structure will have to be rebuilt!!!

Much needed overhaul of the VM system. Included in this first round of
changes:

1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages,
   haspage, and sync operations are supported. The haspage interface now
   provides information about clusterability. All pager routines now take
   struct vm_object's instead of "pagers".

2) Improved data structures. In the previous paradigm, there is constant
   confusion caused by pagers being both a data structure ("allocate a
   pager") and a collection of routines. The idea of a pager structure has
   escentially been eliminated. Objects now have types, and this type is
   used to index the appropriate pager. In most cases, items in the pager
   structure were duplicated in the object data structure and thus were
   unnecessary. In the few cases that remained, a un_pager structure union
   was created in the object to contain these items.

3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now
   be removed. For instance, vm_object_enter(), vm_object_lookup(),
   vm_object_remove(), and the associated object hash list were some of the
   things that were removed.

4) simple_lock's removed. Discussion with several people reveals that the
   SMP locking primitives used in the VM system aren't likely the mechanism
   that we'll be adopting. Even if it were, the locking that was in the code
   was very inadequate and would have to be mostly re-done anyway. The
   locking in a uni-processor kernel was a no-op but went a long way toward
   making the code difficult to read and debug.

5) Places that attempted to kludge-up the fact that we don't have kernel
   thread support have been fixed to reflect the reality that we are really
   dealing with processes, not threads. The VM system didn't have complete
   thread support, so the comments and mis-named routines were just wrong.
   We now use tsleep and wakeup directly in the lock routines, for instance.

6) Where appropriate, the pagers have been improved, especially in the
   pager_alloc routines. Most of the pager_allocs have been rewritten and
   are now faster and easier to maintain.

7) The pagedaemon pageout clustering algorithm has been rewritten and
   now tries harder to output an even number of pages before and after
   the requested page. This is sort of the reverse of the ideal pagein
   algorithm and should provide better overall performance.

8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup
   have been removed. Some other unnecessary casts have also been removed.

9) Some almost useless debugging code removed.

10) Terminology of shadow objects vs. backing objects straightened out.
    The fact that the vm_object data structure escentially had this
    backwards really confused things. The use of "shadow" and "backing
    object" throughout the code is now internally consistent and correct
    in the Mach terminology.

11) Several minor bug fixes, including one in the vm daemon that caused
    0 RSS objects to not get purged as intended.

12) A "default pager" has now been created which cleans up the transition
    of objects to the "swap" type. The previous checks throughout the code
    for swp->pg_data != NULL were really ugly. This change also provides
    the rudiments for future backing of "anonymous" memory by something
    other than the swap pager (via the vnode pager, for example), and it
    allows the decision about which of these pagers to use to be made
    dynamically (although will need some additional decision code to do
    this, of course).

13) (dyson) MAP_COPY has been deprecated and the corresponding "copy
    object" code has been removed. MAP_COPY was undocumented and non-
    standard. It was furthermore broken in several ways which caused its
    behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will
    continue to work correctly, but via the slightly different semantics
    of MAP_PRIVATE.

14) (dyson) Sharing maps have been removed. It's marginal usefulness in a
    threads design can be worked around in other ways. Both #12 and #13
    were done to simplify the code and improve readability and maintain-
    ability. (As were most all of these changes)

TODO:

1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing
   this will reduce the vnode pager to a mere fraction of its current size.

2) Rewrite vm_fault and the swap/vnode pagers to use the clustering
   information provided by the new haspage pager interface. This will
   substantially reduce the overhead by eliminating a large number of
   VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be
   improved to provide both a "behind" and "ahead" indication of
   contiguousness.

3) Implement the extended features of pager_haspage in swap_pager_haspage().
   It currently just says 0 pages ahead/behind.

4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps
   via a much more general mechanism that could also be used for disk
   striping of regular filesystems.

5) Do something to improve the architecture of vm_object_collapse(). The
   fact that it makes calls into the swap pager and knows too much about
   how the swap pager operates really bothers me. It also doesn't allow
   for collapsing of non-swap pager objects ("unnamed" objects backed by
   other pagers).
1995-07-13 08:48:48 +00:00

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/*
* Copyright (c) 1990 University of Utah.
* Copyright (c) 1991 The Regents of the University of California.
* All rights reserved.
* Copyright (c) 1993, 1994 John S. Dyson
* Copyright (c) 1995, David Greenman
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department.
*
* 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.
*
* from: @(#)vnode_pager.c 7.5 (Berkeley) 4/20/91
* $Id: vnode_pager.c,v 1.43 1995/07/09 06:58:03 davidg Exp $
*/
/*
* Page to/from files (vnodes).
*/
/*
* TODO:
* Implement VOP_GETPAGES/PUTPAGES interface for filesystems. Will
* greatly re-simplify the vnode_pager.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/vnode.h>
#include <sys/uio.h>
#include <sys/mount.h>
#include <sys/buf.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
#include <vm/vnode_pager.h>
struct pagerops vnodepagerops = {
NULL,
vnode_pager_alloc,
vnode_pager_dealloc,
vnode_pager_getpages,
vnode_pager_putpages,
vnode_pager_haspage,
NULL
};
/*
* Allocate (or lookup) pager for a vnode.
* Handle is a vnode pointer.
*/
vm_object_t
vnode_pager_alloc(handle, size, prot, offset)
void *handle;
vm_size_t size;
vm_prot_t prot;
vm_offset_t offset;
{
vm_object_t object;
struct vnode *vp;
/*
* Pageout to vnode, no can do yet.
*/
if (handle == NULL)
return (NULL);
vp = (struct vnode *) handle;
/*
* Prevent race condition when allocating the object. This
* can happen with NFS vnodes since the nfsnode isn't locked.
*/
while (vp->v_flag & VOLOCK) {
vp->v_flag |= VOWANT;
tsleep(vp, PVM, "vnpobj", 0);
}
vp->v_flag |= VOLOCK;
/*
* If the object is being terminated, wait for it to
* go away.
*/
while (((object = vp->v_object) != NULL) && (object->flags & OBJ_DEAD)) {
tsleep(object, PVM, "vadead", 0);
}
if (object == NULL) {
/*
* And an object of the appropriate size
*/
object = vm_object_allocate(OBJT_VNODE, round_page(size));
object->flags = OBJ_CANPERSIST;
/*
* Hold a reference to the vnode and initialize object data.
*/
VREF(vp);
object->un_pager.vnp.vnp_size = size;
object->handle = handle;
vp->v_object = object;
} else {
/*
* vm_object_reference() will remove the object from the cache if
* found and gain a reference to the object.
*/
vm_object_reference(object);
}
if (vp->v_type == VREG)
vp->v_flag |= VVMIO;
vp->v_flag &= ~VOLOCK;
if (vp->v_flag & VOWANT) {
vp->v_flag &= ~VOWANT;
wakeup(vp);
}
return (object);
}
void
vnode_pager_dealloc(object)
vm_object_t object;
{
register struct vnode *vp = object->handle;
if (vp == NULL)
panic("vnode_pager_dealloc: pager already dealloced");
if (object->paging_in_progress) {
int s = splbio();
while (object->paging_in_progress) {
object->flags |= OBJ_PIPWNT;
tsleep(object, PVM, "vnpdea", 0);
}
splx(s);
}
object->handle = NULL;
vp->v_object = NULL;
vp->v_flag &= ~(VTEXT | VVMIO);
vp->v_flag |= VAGE;
vrele(vp);
}
boolean_t
vnode_pager_haspage(object, offset, before, after)
vm_object_t object;
vm_offset_t offset;
int *before;
int *after;
{
struct vnode *vp = object->handle;
daddr_t bn;
int err, run;
daddr_t startblock, reqblock;
/*
* If filesystem no longer mounted or offset beyond end of file we do
* not have the page.
*/
if ((vp->v_mount == NULL) || (offset >= object->un_pager.vnp.vnp_size))
return FALSE;
startblock = reqblock = offset / vp->v_mount->mnt_stat.f_iosize;
if (startblock > PFCLUSTER_BEHIND)
startblock -= PFCLUSTER_BEHIND;
else
startblock = 0;;
if (before != NULL) {
/*
* Loop looking for a contiguous chunk that includes the
* requested page.
*/
while (TRUE) {
err = VOP_BMAP(vp, startblock, (struct vnode **) 0, &bn, &run);
if (err || bn == -1) {
if (startblock < reqblock) {
startblock++;
continue;
}
*before = 0;
if (after != NULL)
*after = 0;
return err ? TRUE : FALSE;
}
if ((startblock + run) < reqblock) {
startblock += run + 1;
continue;
}
*before = reqblock - startblock;
if (after != NULL)
*after = run;
return TRUE;
}
}
err = VOP_BMAP(vp, reqblock, (struct vnode **) 0, &bn, after);
if (err)
return TRUE;
return ((long) bn < 0 ? FALSE : TRUE);
}
/*
* Lets the VM system know about a change in size for a file.
* We adjust our own internal size and flush any cached pages in
* the associated object that are affected by the size change.
*
* Note: this routine may be invoked as a result of a pager put
* operation (possibly at object termination time), so we must be careful.
*/
void
vnode_pager_setsize(vp, nsize)
struct vnode *vp;
u_long nsize;
{
vm_object_t object = vp->v_object;
if (object == NULL)
return;
/*
* Hasn't changed size
*/
if (nsize == object->un_pager.vnp.vnp_size)
return;
/*
* File has shrunk. Toss any cached pages beyond the new EOF.
*/
if (nsize < object->un_pager.vnp.vnp_size) {
if (round_page((vm_offset_t) nsize) < object->un_pager.vnp.vnp_size) {
vm_object_page_remove(object,
round_page((vm_offset_t) nsize), object->un_pager.vnp.vnp_size, FALSE);
}
/*
* this gets rid of garbage at the end of a page that is now
* only partially backed by the vnode...
*/
if (nsize & PAGE_MASK) {
vm_offset_t kva;
vm_page_t m;
m = vm_page_lookup(object, trunc_page((vm_offset_t) nsize));
if (m) {
kva = vm_pager_map_page(m);
bzero((caddr_t) kva + (nsize & PAGE_MASK),
round_page(nsize) - nsize);
vm_pager_unmap_page(kva);
}
}
}
object->un_pager.vnp.vnp_size = (vm_offset_t) nsize;
object->size = round_page(nsize);
}
void
vnode_pager_umount(mp)
register struct mount *mp;
{
struct vnode *vp, *nvp;
loop:
for (vp = mp->mnt_vnodelist.lh_first; vp != NULL; vp = nvp) {
/*
* Vnode can be reclaimed by getnewvnode() while we
* traverse the list.
*/
if (vp->v_mount != mp)
goto loop;
/*
* Save the next pointer now since uncaching may terminate the
* object and render vnode invalid
*/
nvp = vp->v_mntvnodes.le_next;
if (vp->v_object != NULL) {
VOP_LOCK(vp);
vnode_pager_uncache(vp);
VOP_UNLOCK(vp);
}
}
}
/*
* Remove vnode associated object from the object cache.
* This routine must be called with the vnode locked.
*
* XXX unlock the vnode.
* We must do this since uncaching the object may result in its
* destruction which may initiate paging activity which may necessitate
* re-locking the vnode.
*/
void
vnode_pager_uncache(vp)
struct vnode *vp;
{
vm_object_t object;
/*
* Not a mapped vnode
*/
object = vp->v_object;
if (object == NULL)
return;
vm_object_reference(object);
VOP_UNLOCK(vp);
pager_cache(object, FALSE);
VOP_LOCK(vp);
return;
}
void
vnode_pager_freepage(m)
vm_page_t m;
{
PAGE_WAKEUP(m);
vm_page_free(m);
}
/*
* calculate the linear (byte) disk address of specified virtual
* file address
*/
vm_offset_t
vnode_pager_addr(vp, address, run)
struct vnode *vp;
vm_offset_t address;
int *run;
{
int rtaddress;
int bsize;
vm_offset_t block;
struct vnode *rtvp;
int err;
int vblock, voffset;
if ((int) address < 0)
return -1;
bsize = vp->v_mount->mnt_stat.f_iosize;
vblock = address / bsize;
voffset = address % bsize;
err = VOP_BMAP(vp, vblock, &rtvp, &block, run);
if (err || (block == -1))
rtaddress = -1;
else {
rtaddress = block + voffset / DEV_BSIZE;
if( run) {
*run += 1;
*run *= bsize/PAGE_SIZE;
*run -= voffset/PAGE_SIZE;
}
}
return rtaddress;
}
/*
* interrupt routine for I/O completion
*/
void
vnode_pager_iodone(bp)
struct buf *bp;
{
bp->b_flags |= B_DONE;
wakeup(bp);
}
/*
* small block file system vnode pager input
*/
int
vnode_pager_input_smlfs(object, m)
vm_object_t object;
vm_page_t m;
{
int i;
int s;
struct vnode *dp, *vp;
struct buf *bp;
vm_offset_t kva;
int fileaddr;
vm_offset_t bsize;
int error = 0;
vp = object->handle;
bsize = vp->v_mount->mnt_stat.f_iosize;
VOP_BMAP(vp, 0, &dp, 0, 0);
kva = vm_pager_map_page(m);
for (i = 0; i < PAGE_SIZE / bsize; i++) {
if ((vm_page_bits(m->offset + i * bsize, bsize) & m->valid))
continue;
fileaddr = vnode_pager_addr(vp, m->offset + i * bsize, (int *)0);
if (fileaddr != -1) {
bp = getpbuf();
/* build a minimal buffer header */
bp->b_flags = B_BUSY | B_READ | B_CALL;
bp->b_iodone = vnode_pager_iodone;
bp->b_proc = curproc;
bp->b_rcred = bp->b_wcred = bp->b_proc->p_ucred;
if (bp->b_rcred != NOCRED)
crhold(bp->b_rcred);
if (bp->b_wcred != NOCRED)
crhold(bp->b_wcred);
bp->b_un.b_addr = (caddr_t) kva + i * bsize;
bp->b_blkno = fileaddr;
pbgetvp(dp, bp);
bp->b_bcount = bsize;
bp->b_bufsize = bsize;
/* do the input */
VOP_STRATEGY(bp);
/* we definitely need to be at splbio here */
s = splbio();
while ((bp->b_flags & B_DONE) == 0) {
tsleep(bp, PVM, "vnsrd", 0);
}
splx(s);
if ((bp->b_flags & B_ERROR) != 0)
error = EIO;
/*
* free the buffer header back to the swap buffer pool
*/
relpbuf(bp);
if (error)
break;
vm_page_set_clean(m, (i * bsize) & (PAGE_SIZE-1), bsize);
vm_page_set_valid(m, (i * bsize) & (PAGE_SIZE-1), bsize);
} else {
vm_page_set_clean(m, (i * bsize) & (PAGE_SIZE-1), bsize);
bzero((caddr_t) kva + i * bsize, bsize);
}
}
vm_pager_unmap_page(kva);
pmap_clear_modify(VM_PAGE_TO_PHYS(m));
if (error) {
return VM_PAGER_ERROR;
}
return VM_PAGER_OK;
}
/*
* old style vnode pager output routine
*/
int
vnode_pager_input_old(object, m)
vm_object_t object;
vm_page_t m;
{
struct uio auio;
struct iovec aiov;
int error;
int size;
vm_offset_t kva;
error = 0;
/*
* Return failure if beyond current EOF
*/
if (m->offset >= object->un_pager.vnp.vnp_size) {
return VM_PAGER_BAD;
} else {
size = PAGE_SIZE;
if (m->offset + size > object->un_pager.vnp.vnp_size)
size = object->un_pager.vnp.vnp_size - m->offset;
/*
* Allocate a kernel virtual address and initialize so that
* we can use VOP_READ/WRITE routines.
*/
kva = vm_pager_map_page(m);
aiov.iov_base = (caddr_t) kva;
aiov.iov_len = size;
auio.uio_iov = &aiov;
auio.uio_iovcnt = 1;
auio.uio_offset = m->offset;
auio.uio_segflg = UIO_SYSSPACE;
auio.uio_rw = UIO_READ;
auio.uio_resid = size;
auio.uio_procp = (struct proc *) 0;
error = VOP_READ(object->handle, &auio, 0, curproc->p_ucred);
if (!error) {
register int count = size - auio.uio_resid;
if (count == 0)
error = EINVAL;
else if (count != PAGE_SIZE)
bzero((caddr_t) kva + count, PAGE_SIZE - count);
}
vm_pager_unmap_page(kva);
}
pmap_clear_modify(VM_PAGE_TO_PHYS(m));
m->dirty = 0;
return error ? VM_PAGER_ERROR : VM_PAGER_OK;
}
/*
* generic vnode pager input routine
*/
int
vnode_pager_getpages(object, m, count, reqpage)
vm_object_t object;
vm_page_t *m;
int count;
int reqpage;
{
vm_offset_t kva, foff;
int i, size, bsize, first, firstaddr;
struct vnode *dp, *vp;
int runpg;
int runend;
struct buf *bp;
int s;
int error = 0;
vp = object->handle;
bsize = vp->v_mount->mnt_stat.f_iosize;
/* get the UNDERLYING device for the file with VOP_BMAP() */
/*
* originally, we did not check for an error return value -- assuming
* an fs always has a bmap entry point -- that assumption is wrong!!!
*/
foff = m[reqpage]->offset;
/*
* if we can't bmap, use old VOP code
*/
if (VOP_BMAP(vp, 0, &dp, 0, 0)) {
for (i = 0; i < count; i++) {
if (i != reqpage) {
vnode_pager_freepage(m[i]);
}
}
cnt.v_vnodein++;
cnt.v_vnodepgsin++;
return vnode_pager_input_old(object, m[reqpage]);
/*
* if the blocksize is smaller than a page size, then use
* special small filesystem code. NFS sometimes has a small
* blocksize, but it can handle large reads itself.
*/
} else if ((PAGE_SIZE / bsize) > 1 &&
(vp->v_mount->mnt_stat.f_type != MOUNT_NFS)) {
for (i = 0; i < count; i++) {
if (i != reqpage) {
vnode_pager_freepage(m[i]);
}
}
cnt.v_vnodein++;
cnt.v_vnodepgsin++;
return vnode_pager_input_smlfs(object, m[reqpage]);
}
/*
* if ANY DEV_BSIZE blocks are valid on a large filesystem block
* then, the entire page is valid --
*/
if (m[reqpage]->valid) {
m[reqpage]->valid = VM_PAGE_BITS_ALL;
for (i = 0; i < count; i++) {
if (i != reqpage)
vnode_pager_freepage(m[i]);
}
return VM_PAGER_OK;
}
/*
* here on direct device I/O
*/
firstaddr = -1;
/*
* calculate the run that includes the required page
*/
for(first = 0, i = 0; i < count; i = runend) {
firstaddr = vnode_pager_addr(vp, m[i]->offset, &runpg);
if (firstaddr == -1) {
if (i == reqpage && foff < object->un_pager.vnp.vnp_size) {
panic("vnode_pager_putpages: unexpected missing page: firstaddr: %d, foff: %ld, vnp_size: %d",
firstaddr, foff, object->un_pager.vnp.vnp_size);
}
vnode_pager_freepage(m[i]);
runend = i + 1;
first = runend;
continue;
}
runend = i + runpg;
if (runend <= reqpage) {
int j;
for (j = i; j < runend; j++) {
vnode_pager_freepage(m[j]);
}
} else {
if (runpg < (count - first)) {
for (i = first + runpg; i < count; i++)
vnode_pager_freepage(m[i]);
count = first + runpg;
}
break;
}
first = runend;
}
/*
* the first and last page have been calculated now, move input pages
* to be zero based...
*/
if (first != 0) {
for (i = first; i < count; i++) {
m[i - first] = m[i];
}
count -= first;
reqpage -= first;
}
/*
* calculate the file virtual address for the transfer
*/
foff = m[0]->offset;
/*
* calculate the size of the transfer
*/
size = count * PAGE_SIZE;
if ((foff + size) > object->un_pager.vnp.vnp_size)
size = object->un_pager.vnp.vnp_size - foff;
/*
* round up physical size for real devices
*/
if (dp->v_type == VBLK || dp->v_type == VCHR)
size = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
bp = getpbuf();
kva = (vm_offset_t) bp->b_data;
/*
* and map the pages to be read into the kva
*/
pmap_qenter(kva, m, count);
/* build a minimal buffer header */
bp->b_flags = B_BUSY | B_READ | B_CALL;
bp->b_iodone = vnode_pager_iodone;
/* B_PHYS is not set, but it is nice to fill this in */
bp->b_proc = curproc;
bp->b_rcred = bp->b_wcred = bp->b_proc->p_ucred;
if (bp->b_rcred != NOCRED)
crhold(bp->b_rcred);
if (bp->b_wcred != NOCRED)
crhold(bp->b_wcred);
bp->b_blkno = firstaddr;
pbgetvp(dp, bp);
bp->b_bcount = size;
bp->b_bufsize = size;
cnt.v_vnodein++;
cnt.v_vnodepgsin += count;
/* do the input */
VOP_STRATEGY(bp);
s = splbio();
/* we definitely need to be at splbio here */
while ((bp->b_flags & B_DONE) == 0) {
tsleep(bp, PVM, "vnread", 0);
}
splx(s);
if ((bp->b_flags & B_ERROR) != 0)
error = EIO;
if (!error) {
if (size != count * PAGE_SIZE)
bzero((caddr_t) kva + size, PAGE_SIZE * count - size);
}
pmap_qremove(kva, count);
/*
* free the buffer header back to the swap buffer pool
*/
relpbuf(bp);
for (i = 0; i < count; i++) {
pmap_clear_modify(VM_PAGE_TO_PHYS(m[i]));
m[i]->dirty = 0;
m[i]->valid = VM_PAGE_BITS_ALL;
if (i != reqpage) {
/*
* whether or not to leave the page activated is up in
* the air, but we should put the page on a page queue
* somewhere. (it already is in the object). Result:
* It appears that emperical results show that
* deactivating pages is best.
*/
/*
* just in case someone was asking for this page we
* now tell them that it is ok to use
*/
if (!error) {
vm_page_deactivate(m[i]);
PAGE_WAKEUP(m[i]);
} else {
vnode_pager_freepage(m[i]);
}
}
}
if (error) {
printf("vnode_pager_getpages: I/O read error\n");
}
return (error ? VM_PAGER_ERROR : VM_PAGER_OK);
}
/*
* generic vnode pager output routine
*/
int
vnode_pager_putpages(object, m, count, sync, rtvals)
vm_object_t object;
vm_page_t *m;
int count;
boolean_t sync;
int *rtvals;
{
int i;
struct vnode *vp;
int maxsize, ncount;
struct uio auio;
struct iovec aiov;
int error;
vp = object->handle;;
for (i = 0; i < count; i++)
rtvals[i] = VM_PAGER_AGAIN;
if ((int) m[0]->offset < 0) {
printf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%x(%x)\n", m[0]->offset, m[0]->dirty);
rtvals[0] = VM_PAGER_BAD;
return VM_PAGER_BAD;
}
maxsize = count * PAGE_SIZE;
ncount = count;
if (maxsize + m[0]->offset > object->un_pager.vnp.vnp_size) {
if (object->un_pager.vnp.vnp_size > m[0]->offset)
maxsize = object->un_pager.vnp.vnp_size - m[0]->offset;
else
maxsize = 0;
ncount = (maxsize + PAGE_SIZE - 1) / PAGE_SIZE;
if (ncount < count) {
for (i = ncount; i < count; i++) {
rtvals[i] = VM_PAGER_BAD;
}
if (ncount == 0) {
printf("vnode_pager_putpages: write past end of file: %d, %d\n",
m[0]->offset, object->un_pager.vnp.vnp_size);
return rtvals[0];
}
}
}
for (i = 0; i < count; i++) {
m[i]->busy++;
m[i]->flags &= ~PG_BUSY;
}
aiov.iov_base = (caddr_t) 0;
aiov.iov_len = maxsize;
auio.uio_iov = &aiov;
auio.uio_iovcnt = 1;
auio.uio_offset = m[0]->offset;
auio.uio_segflg = UIO_NOCOPY;
auio.uio_rw = UIO_WRITE;
auio.uio_resid = maxsize;
auio.uio_procp = (struct proc *) 0;
error = VOP_WRITE(vp, &auio, IO_VMIO, curproc->p_ucred);
cnt.v_vnodeout++;
cnt.v_vnodepgsout += ncount;
if (error) {
printf("vnode_pager_putpages: I/O error %d\n", error);
}
if (auio.uio_resid) {
printf("vnode_pager_putpages: residual I/O %d at %d\n", auio.uio_resid, m[0]->offset);
}
for (i = 0; i < count; i++) {
m[i]->busy--;
if (i < ncount) {
rtvals[i] = VM_PAGER_OK;
}
if ((m[i]->busy == 0) && (m[i]->flags & PG_WANTED))
wakeup(m[i]);
}
return rtvals[0];
}
struct vnode *
vnode_pager_lock(object)
vm_object_t object;
{
for (; object != NULL; object = object->backing_object) {
if (object->type != OBJT_VNODE)
continue;
VOP_LOCK(object->handle);
return object->handle;
}
return NULL;
}
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