2 * Copyright (c) 1990 University of Utah.
3 * Copyright (c) 1991 The Regents of the University of California.
5 * Copyright (c) 1993, 1994 John S. Dyson
6 * Copyright (c) 1995, David Greenman
8 * This code is derived from software contributed to Berkeley by
9 * the Systems Programming Group of the University of Utah Computer
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the University of
23 * California, Berkeley and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 * may be used to endorse or promote products derived from this software
26 * without specific prior written permission.
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
40 * from: @(#)vnode_pager.c 7.5 (Berkeley) 4/20/91
41 * $FreeBSD: src/sys/vm/vnode_pager.c,v 1.116.2.7 2002/12/31 09:34:51 dillon Exp $
42 * $DragonFly: src/sys/vm/vnode_pager.c,v 1.43 2008/06/19 23:27:39 dillon Exp $
46 * Page to/from files (vnodes).
51 * Implement VOP_GETPAGES/PUTPAGES interface for filesystems. Will
52 * greatly re-simplify the vnode_pager.
55 #include <sys/param.h>
56 #include <sys/systm.h>
57 #include <sys/kernel.h>
59 #include <sys/vnode.h>
60 #include <sys/mount.h>
62 #include <sys/vmmeter.h>
64 #include <sys/sfbuf.h>
67 #include <vm/vm_object.h>
68 #include <vm/vm_page.h>
69 #include <vm/vm_pager.h>
70 #include <vm/vm_map.h>
71 #include <vm/vnode_pager.h>
72 #include <vm/vm_extern.h>
74 #include <sys/thread2.h>
75 #include <vm/vm_page2.h>
77 static void vnode_pager_dealloc (vm_object_t);
78 static int vnode_pager_getpages (vm_object_t, vm_page_t *, int, int);
79 static void vnode_pager_putpages (vm_object_t, vm_page_t *, int, boolean_t, int *);
80 static boolean_t vnode_pager_haspage (vm_object_t, vm_pindex_t, int *, int *);
82 struct pagerops vnodepagerops = {
92 static struct krate vbadrate = { 1 };
93 static struct krate vresrate = { 1 };
95 int vnode_pbuf_freecnt = -1; /* start out unlimited */
98 * Allocate (or lookup) pager for a vnode.
99 * Handle is a vnode pointer.
102 vnode_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t offset)
108 * Pageout to vnode, no can do yet.
114 * XXX hack - This initialization should be put somewhere else.
116 if (vnode_pbuf_freecnt < 0) {
117 vnode_pbuf_freecnt = nswbuf / 2 + 1;
120 vp = (struct vnode *) handle;
123 * Prevent race condition when allocating the object. This
124 * can happen with NFS vnodes since the nfsnode isn't locked.
126 while (vp->v_flag & VOLOCK) {
127 vsetflags(vp, VOWANT);
128 tsleep(vp, 0, "vnpobj", 0);
130 vsetflags(vp, VOLOCK);
133 * If the object is being terminated, wait for it to
136 while (((object = vp->v_object) != NULL) &&
137 (object->flags & OBJ_DEAD)) {
138 vm_object_dead_sleep(object, "vadead");
141 if (vp->v_sysref.refcnt <= 0)
142 panic("vnode_pager_alloc: no vnode reference");
144 if (object == NULL) {
146 * And an object of the appropriate size
148 object = vm_object_allocate(OBJT_VNODE, OFF_TO_IDX(round_page(size)));
150 object->handle = handle;
151 vp->v_object = object;
152 vp->v_filesize = size;
155 if (vp->v_filesize != size) {
156 kprintf("vnode_pager_alloc: Warning, filesize "
157 "mismatch %lld/%lld\n",
158 (long long)vp->v_filesize,
164 vclrflags(vp, VOLOCK);
165 if (vp->v_flag & VOWANT) {
166 vclrflags(vp, VOWANT);
173 vnode_pager_dealloc(vm_object_t object)
175 struct vnode *vp = object->handle;
178 panic("vnode_pager_dealloc: pager already dealloced");
180 vm_object_pip_wait(object, "vnpdea");
182 object->handle = NULL;
183 object->type = OBJT_DEAD;
185 vp->v_filesize = NOOFFSET;
186 vclrflags(vp, VTEXT | VOBJBUF);
190 * Return whether the vnode pager has the requested page. Return the
191 * number of disk-contiguous pages before and after the requested page,
192 * not including the requested page.
195 vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
198 struct vnode *vp = object->handle;
206 * If no vp or vp is doomed or marked transparent to VM, we do not
209 if ((vp == NULL) || (vp->v_flag & VRECLAIMED))
213 * If filesystem no longer mounted or offset beyond end of file we do
216 loffset = IDX_TO_OFF(pindex);
218 if (vp->v_mount == NULL || loffset >= vp->v_filesize)
221 bsize = vp->v_mount->mnt_stat.f_iosize;
222 voff = loffset % bsize;
225 * BMAP returns byte counts before and after, where after
226 * is inclusive of the base page. haspage must return page
227 * counts before and after where after does not include the
230 * BMAP is allowed to return a *after of 0 for backwards
231 * compatibility. The base page is still considered valid if
232 * no error is returned.
234 error = VOP_BMAP(vp, loffset - voff, &doffset, after, before, 0);
242 if (doffset == NOOFFSET)
246 *before = (*before + voff) >> PAGE_SHIFT;
250 if (loffset + *after > vp->v_filesize)
251 *after = vp->v_filesize - loffset;
252 *after >>= PAGE_SHIFT;
260 * Lets the VM system know about a change in size for a file.
261 * We adjust our own internal size and flush any cached pages in
262 * the associated object that are affected by the size change.
264 * NOTE: This routine may be invoked as a result of a pager put
265 * operation (possibly at object termination time), so we must be careful.
267 * NOTE: vp->v_filesize is initialized to NOOFFSET (-1), be sure that
268 * we do not blow up on the case. nsize will always be >= 0, however.
271 vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize)
273 vm_pindex_t nobjsize;
274 vm_pindex_t oobjsize;
275 vm_object_t object = vp->v_object;
281 * Hasn't changed size
283 if (nsize == vp->v_filesize)
287 * Has changed size. Adjust the VM object's size and v_filesize
288 * before we start scanning pages to prevent new pages from being
289 * allocated during the scan.
291 nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
292 oobjsize = object->size;
293 object->size = nobjsize;
296 * File has shrunk. Toss any cached pages beyond the new EOF.
298 if (nsize < vp->v_filesize) {
299 vp->v_filesize = nsize;
300 if (nobjsize < oobjsize) {
301 vm_object_page_remove(object, nobjsize, oobjsize,
305 * This gets rid of garbage at the end of a page that is now
306 * only partially backed by the vnode. Since we are setting
307 * the entire page valid & clean after we are done we have
308 * to be sure that the portion of the page within the file
309 * bounds is already valid. If it isn't then making it
310 * valid would create a corrupt block.
312 if (nsize & PAGE_MASK) {
317 m = vm_page_lookup(object, OFF_TO_IDX(nsize));
318 } while (m && vm_page_sleep_busy(m, TRUE, "vsetsz"));
321 int base = (int)nsize & PAGE_MASK;
322 int size = PAGE_SIZE - base;
326 * Clear out partial-page garbage in case
327 * the page has been mapped.
329 * This is byte aligned.
332 sf = sf_buf_alloc(m, SFB_CPUPRIVATE);
333 kva = sf_buf_kva(sf);
334 bzero((caddr_t)kva + base, size);
338 * XXX work around SMP data integrity race
339 * by unmapping the page from user processes.
340 * The garbage we just cleared may be mapped
341 * to a user process running on another cpu
342 * and this code is not running through normal
343 * I/O channels which handle SMP issues for
344 * us, so unmap page to synchronize all cpus.
346 * XXX should vm_pager_unmap_page() have
349 vm_page_protect(m, VM_PROT_NONE);
352 * Clear out partial-page dirty bits. This
353 * has the side effect of setting the valid
354 * bits, but that is ok. There are a bunch
355 * of places in the VM system where we expected
356 * m->dirty == VM_PAGE_BITS_ALL. The file EOF
357 * case is one of them. If the page is still
358 * partially dirty, make it fully dirty.
360 * NOTE: We do not clear out the valid
361 * bits. This would prevent bogus_page
362 * replacement from working properly.
364 * NOTE: We do not want to clear the dirty
365 * bit for a partial DEV_BSIZE'd truncation!
366 * This is DEV_BSIZE aligned!
368 vm_page_clear_dirty_beg_nonincl(m, base, size);
370 m->dirty = VM_PAGE_BITS_ALL;
375 vp->v_filesize = nsize;
380 * Release a page busied for a getpages operation. The page may have become
381 * wired (typically due to being used by the buffer cache) or otherwise been
382 * soft-busied and cannot be freed in that case. A held page can still be
386 vnode_pager_freepage(vm_page_t m)
388 if (m->busy || m->wire_count) {
397 * EOPNOTSUPP is no longer legal. For local media VFS's that do not
398 * implement their own VOP_GETPAGES, their VOP_GETPAGES should call to
399 * vnode_pager_generic_getpages() to implement the previous behaviour.
401 * All other FS's should use the bypass to get to the local media
402 * backing vp's VOP_GETPAGES.
405 vnode_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
409 int bytes = count * PAGE_SIZE;
412 rtval = VOP_GETPAGES(vp, m, bytes, reqpage, 0);
413 if (rtval == EOPNOTSUPP)
414 panic("vnode_pager: vfs's must implement vop_getpages\n");
419 * This is now called from local media FS's to operate against their
420 * own vnodes if they fail to implement VOP_GETPAGES.
422 * With all the caching local media devices do these days there is really
423 * very little point to attempting to restrict the I/O size to contiguous
424 * blocks on-disk, especially if our caller thinks we need all the specified
425 * pages. Just construct and issue a READ.
428 vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int bytecount,
440 * Do not do anything if the vnode is bad.
442 if (vp->v_mount == NULL)
446 * Calculate the number of pages. Since we are paging in whole
447 * pages, adjust bytecount to be an integral multiple of the page
448 * size. It will be clipped to the file EOF later on.
450 bytecount = round_page(bytecount);
451 count = bytecount / PAGE_SIZE;
454 * We could check m[reqpage]->valid here and shortcut the operation,
455 * but doing so breaks read-ahead. Instead assume that the VM
456 * system has already done at least the check, don't worry about
457 * any races, and issue the VOP_READ to allow read-ahead to function.
459 * This keeps the pipeline full for I/O bound sequentially scanned
465 * Discard pages past the file EOF. If the requested page is past
466 * the file EOF we just leave its valid bits set to 0, the caller
467 * expects to maintain ownership of the requested page. If the
468 * entire range is past file EOF discard everything and generate
471 foff = IDX_TO_OFF(m[0]->pindex);
472 if (foff >= vp->v_filesize) {
473 for (i = 0; i < count; i++) {
475 vnode_pager_freepage(m[i]);
477 return VM_PAGER_ERROR;
480 if (foff + bytecount > vp->v_filesize) {
481 bytecount = vp->v_filesize - foff;
482 i = round_page(bytecount) / PAGE_SIZE;
485 if (count != reqpage)
486 vnode_pager_freepage(m[count]);
491 * The size of the transfer is bytecount. bytecount will be an
492 * integral multiple of the page size unless it has been clipped
493 * to the file EOF. The transfer cannot exceed the file EOF.
495 * When dealing with real devices we must round-up to the device
498 if (vp->v_type == VBLK || vp->v_type == VCHR) {
499 int secmask = vp->v_rdev->si_bsize_phys - 1;
500 KASSERT(secmask < PAGE_SIZE, ("vnode_pager_generic_getpages: sector size %d too large\n", secmask + 1));
501 bytecount = (bytecount + secmask) & ~secmask;
505 * Severe hack to avoid deadlocks with the buffer cache
507 for (i = 0; i < count; ++i) {
510 vm_page_io_start(mt);
515 * Issue the I/O with some read-ahead if bytecount > PAGE_SIZE
518 /* if (bytecount > PAGE_SIZE)*/
519 ioflags |= IO_SEQMAX << IO_SEQSHIFT;
521 aiov.iov_base = (caddr_t) 0;
522 aiov.iov_len = bytecount;
523 auio.uio_iov = &aiov;
525 auio.uio_offset = foff;
526 auio.uio_segflg = UIO_NOCOPY;
527 auio.uio_rw = UIO_READ;
528 auio.uio_resid = bytecount;
530 mycpu->gd_cnt.v_vnodein++;
531 mycpu->gd_cnt.v_vnodepgsin += count;
533 error = VOP_READ(vp, &auio, ioflags, proc0.p_ucred);
536 * Severe hack to avoid deadlocks with the buffer cache
538 for (i = 0; i < count; ++i) {
541 while (vm_page_sleep_busy(mt, FALSE, "getpgs"))
544 vm_page_io_finish(mt);
548 * Calculate the actual number of bytes read and clean up the
551 bytecount -= auio.uio_resid;
553 for (i = 0; i < count; ++i) {
557 if (error == 0 && mt->valid) {
558 if (mt->flags & PG_WANTED)
559 vm_page_activate(mt);
561 vm_page_deactivate(mt);
564 vnode_pager_freepage(mt);
566 } else if (mt->valid == 0) {
568 kprintf("page failed but no I/O error page %p object %p pindex %d\n", mt, mt->object, (int) mt->pindex);
569 /* whoops, something happened */
572 } else if (mt->valid != VM_PAGE_BITS_ALL) {
574 * Zero-extend the requested page if necessary (if
575 * the filesystem is using a small block size).
577 vm_page_zero_invalid(mt, TRUE);
581 kprintf("vnode_pager_getpages: I/O read error\n");
583 return (error ? VM_PAGER_ERROR : VM_PAGER_OK);
587 * EOPNOTSUPP is no longer legal. For local media VFS's that do not
588 * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to
589 * vnode_pager_generic_putpages() to implement the previous behaviour.
591 * Caller has already cleared the pmap modified bits, if any.
593 * All other FS's should use the bypass to get to the local media
594 * backing vp's VOP_PUTPAGES.
597 vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count,
598 boolean_t sync, int *rtvals)
602 int bytes = count * PAGE_SIZE;
605 * Force synchronous operation if we are extremely low on memory
606 * to prevent a low-memory deadlock. VOP operations often need to
607 * allocate more memory to initiate the I/O ( i.e. do a BMAP
608 * operation ). The swapper handles the case by limiting the amount
609 * of asynchronous I/O, but that sort of solution doesn't scale well
610 * for the vnode pager without a lot of work.
612 * Also, the backing vnode's iodone routine may not wake the pageout
613 * daemon up. This should be probably be addressed XXX.
616 if ((vmstats.v_free_count + vmstats.v_cache_count) < vmstats.v_pageout_free_min)
620 * Call device-specific putpages function
623 rtval = VOP_PUTPAGES(vp, m, bytes, sync, rtvals, 0);
624 if (rtval == EOPNOTSUPP) {
625 kprintf("vnode_pager: *** WARNING *** stale FS putpages\n");
626 rtval = vnode_pager_generic_putpages( vp, m, bytes, sync, rtvals);
632 * This is now called from local media FS's to operate against their
633 * own vnodes if they fail to implement VOP_PUTPAGES.
635 * This is typically called indirectly via the pageout daemon and
636 * clustering has already typically occured, so in general we ask the
637 * underlying filesystem to write the data out asynchronously rather
641 vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *m, int bytecount,
642 int flags, int *rtvals)
646 int maxsize, ncount, count;
647 vm_ooffset_t poffset;
653 object = vp->v_object;
654 count = bytecount / PAGE_SIZE;
656 for (i = 0; i < count; i++)
657 rtvals[i] = VM_PAGER_AGAIN;
659 if ((int) m[0]->pindex < 0) {
660 kprintf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%lx(%x)\n",
661 (long)m[0]->pindex, m[0]->dirty);
662 rtvals[0] = VM_PAGER_BAD;
666 maxsize = count * PAGE_SIZE;
669 poffset = IDX_TO_OFF(m[0]->pindex);
672 * If the page-aligned write is larger then the actual file we
673 * have to invalidate pages occuring beyond the file EOF.
675 * If the file EOF resides in the middle of a page we still clear
676 * all of that page's dirty bits later on. If we didn't it would
677 * endlessly re-write.
679 * We do not under any circumstances truncate the valid bits, as
680 * this will screw up bogus page replacement.
682 * The caller has already read-protected the pages. The VFS must
683 * use the buffer cache to wrap the pages. The pages might not
684 * be immediately flushed by the buffer cache but once under its
685 * control the pages themselves can wind up being marked clean
686 * and their covering buffer cache buffer can be marked dirty.
688 if (poffset + maxsize > vp->v_filesize) {
689 if (poffset < vp->v_filesize) {
690 maxsize = vp->v_filesize - poffset;
691 ncount = btoc(maxsize);
696 if (ncount < count) {
697 for (i = ncount; i < count; i++) {
698 rtvals[i] = VM_PAGER_BAD;
704 * pageouts are already clustered, use IO_ASYNC to force a bawrite()
705 * rather then a bdwrite() to prevent paging I/O from saturating
706 * the buffer cache. Dummy-up the sequential heuristic to cause
707 * large ranges to cluster. If neither IO_SYNC or IO_ASYNC is set,
708 * the system decides how to cluster.
711 if (flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL))
713 else if ((flags & VM_PAGER_CLUSTER_OK) == 0)
715 ioflags |= (flags & VM_PAGER_PUT_INVAL) ? IO_INVAL: 0;
716 ioflags |= IO_SEQMAX << IO_SEQSHIFT;
718 aiov.iov_base = (caddr_t) 0;
719 aiov.iov_len = maxsize;
720 auio.uio_iov = &aiov;
722 auio.uio_offset = poffset;
723 auio.uio_segflg = UIO_NOCOPY;
724 auio.uio_rw = UIO_WRITE;
725 auio.uio_resid = maxsize;
727 error = VOP_WRITE(vp, &auio, ioflags, proc0.p_ucred);
728 mycpu->gd_cnt.v_vnodeout++;
729 mycpu->gd_cnt.v_vnodepgsout += ncount;
732 krateprintf(&vbadrate,
733 "vnode_pager_putpages: I/O error %d\n", error);
735 if (auio.uio_resid) {
736 krateprintf(&vresrate,
737 "vnode_pager_putpages: residual I/O %zd at %lu\n",
738 auio.uio_resid, (u_long)m[0]->pindex);
741 for (i = 0; i < ncount; i++) {
742 rtvals[i] = VM_PAGER_OK;
743 vm_page_undirty(m[i]);
750 vnode_pager_lock(vm_object_t object)
752 struct thread *td = curthread; /* XXX */
755 for (; object != NULL; object = object->backing_object) {
756 if (object->type != OBJT_VNODE)
758 if (object->flags & OBJ_DEAD)
762 struct vnode *vp = object->handle;
763 error = vget(vp, LK_SHARED | LK_RETRY | LK_CANRECURSE);
765 if (object->handle != vp) {
771 if ((object->flags & OBJ_DEAD) ||
772 (object->type != OBJT_VNODE)) {
775 kprintf("vnode_pager_lock: vp %p error %d lockstatus %d, retrying\n", vp, error, lockstatus(&vp->v_lock, td));
776 tsleep(object->handle, 0, "vnpgrl", hz);