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>
65 #include <sys/thread2.h>
68 #include <vm/vm_object.h>
69 #include <vm/vm_page.h>
70 #include <vm/vm_pager.h>
71 #include <vm/vm_map.h>
72 #include <vm/vnode_pager.h>
73 #include <vm/vm_extern.h>
75 static void vnode_pager_dealloc (vm_object_t);
76 static int vnode_pager_getpages (vm_object_t, vm_page_t *, int, int);
77 static void vnode_pager_putpages (vm_object_t, vm_page_t *, int, boolean_t, int *);
78 static boolean_t vnode_pager_haspage (vm_object_t, vm_pindex_t, int *, int *);
80 struct pagerops vnodepagerops = {
90 static struct krate vbadrate = { 1 };
91 static struct krate vresrate = { 1 };
93 int vnode_pbuf_freecnt = -1; /* start out unlimited */
96 * Allocate (or lookup) pager for a vnode.
97 * Handle is a vnode pointer.
100 vnode_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t offset)
106 * Pageout to vnode, no can do yet.
112 * XXX hack - This initialization should be put somewhere else.
114 if (vnode_pbuf_freecnt < 0) {
115 vnode_pbuf_freecnt = nswbuf / 2 + 1;
118 vp = (struct vnode *) handle;
121 * Prevent race condition when allocating the object. This
122 * can happen with NFS vnodes since the nfsnode isn't locked.
124 while (vp->v_flag & VOLOCK) {
125 vp->v_flag |= VOWANT;
126 tsleep(vp, 0, "vnpobj", 0);
128 vp->v_flag |= VOLOCK;
131 * If the object is being terminated, wait for it to
134 while (((object = vp->v_object) != NULL) &&
135 (object->flags & OBJ_DEAD)) {
136 vm_object_dead_sleep(object, "vadead");
139 if (vp->v_sysref.refcnt <= 0)
140 panic("vnode_pager_alloc: no vnode reference");
142 if (object == NULL) {
144 * And an object of the appropriate size
146 object = vm_object_allocate(OBJT_VNODE, OFF_TO_IDX(round_page(size)));
148 object->handle = handle;
149 vp->v_object = object;
150 vp->v_filesize = size;
153 if (vp->v_filesize != size) {
154 kprintf("vnode_pager_alloc: Warning, filesize "
155 "mismatch %lld/%lld\n",
156 (long long)vp->v_filesize,
162 vp->v_flag &= ~VOLOCK;
163 if (vp->v_flag & VOWANT) {
164 vp->v_flag &= ~VOWANT;
171 vnode_pager_dealloc(vm_object_t object)
173 struct vnode *vp = object->handle;
176 panic("vnode_pager_dealloc: pager already dealloced");
178 vm_object_pip_wait(object, "vnpdea");
180 object->handle = NULL;
181 object->type = OBJT_DEAD;
183 vp->v_filesize = NOOFFSET;
184 vp->v_flag &= ~(VTEXT | VOBJBUF);
188 * Return whether the vnode pager has the requested page. Return the
189 * number of disk-contiguous pages before and after the requested page,
190 * not including the requested page.
193 vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
196 struct vnode *vp = object->handle;
204 * If no vp or vp is doomed or marked transparent to VM, we do not
207 if ((vp == NULL) || (vp->v_flag & VRECLAIMED))
211 * If filesystem no longer mounted or offset beyond end of file we do
214 loffset = IDX_TO_OFF(pindex);
216 if (vp->v_mount == NULL || loffset >= vp->v_filesize)
219 bsize = vp->v_mount->mnt_stat.f_iosize;
220 voff = loffset % bsize;
223 * BMAP returns byte counts before and after, where after
224 * is inclusive of the base page. haspage must return page
225 * counts before and after where after does not include the
228 * BMAP is allowed to return a *after of 0 for backwards
229 * compatibility. The base page is still considered valid if
230 * no error is returned.
232 error = VOP_BMAP(vp, loffset - voff, &doffset, after, before, 0);
240 if (doffset == NOOFFSET)
244 *before = (*before + voff) >> PAGE_SHIFT;
248 if (loffset + *after > vp->v_filesize)
249 *after = vp->v_filesize - loffset;
250 *after >>= PAGE_SHIFT;
258 * Lets the VM system know about a change in size for a file.
259 * We adjust our own internal size and flush any cached pages in
260 * the associated object that are affected by the size change.
262 * NOTE: This routine may be invoked as a result of a pager put
263 * operation (possibly at object termination time), so we must be careful.
265 * NOTE: vp->v_filesize is initialized to NOOFFSET (-1), be sure that
266 * we do not blow up on the case. nsize will always be >= 0, however.
269 vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize)
271 vm_pindex_t nobjsize;
272 vm_pindex_t oobjsize;
273 vm_object_t object = vp->v_object;
279 * Hasn't changed size
281 if (nsize == vp->v_filesize)
285 * Has changed size. Adjust the VM object's size and v_filesize
286 * before we start scanning pages to prevent new pages from being
287 * allocated during the scan.
289 nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
290 oobjsize = object->size;
291 object->size = nobjsize;
294 * File has shrunk. Toss any cached pages beyond the new EOF.
296 if (nsize < vp->v_filesize) {
297 vp->v_filesize = nsize;
298 if (nobjsize < oobjsize) {
299 vm_object_page_remove(object, nobjsize, oobjsize,
303 * This gets rid of garbage at the end of a page that is now
304 * only partially backed by the vnode. Since we are setting
305 * the entire page valid & clean after we are done we have
306 * to be sure that the portion of the page within the file
307 * bounds is already valid. If it isn't then making it
308 * valid would create a corrupt block.
310 if (nsize & PAGE_MASK) {
315 m = vm_page_lookup(object, OFF_TO_IDX(nsize));
316 } while (m && vm_page_sleep_busy(m, TRUE, "vsetsz"));
319 int base = (int)nsize & PAGE_MASK;
320 int size = PAGE_SIZE - base;
325 * Clear out partial-page garbage in case
326 * the page has been mapped.
328 * This is byte aligned.
331 sf = sf_buf_alloc(m, SFB_CPUPRIVATE);
332 kva = sf_buf_kva(sf);
333 bzero((caddr_t)kva + base, size);
337 * XXX work around SMP data integrity race
338 * by unmapping the page from user processes.
339 * The garbage we just cleared may be mapped
340 * to a user process running on another cpu
341 * and this code is not running through normal
342 * I/O channels which handle SMP issues for
343 * us, so unmap page to synchronize all cpus.
345 * XXX should vm_pager_unmap_page() have
348 vm_page_protect(m, VM_PROT_NONE);
351 * Clear out partial-page dirty bits. This
352 * has the side effect of setting the valid
353 * bits, but that is ok. There are a bunch
354 * of places in the VM system where we expected
355 * m->dirty == VM_PAGE_BITS_ALL. The file EOF
356 * case is one of them. If the page is still
357 * partially dirty, make it fully dirty.
359 * NOTE: We do not clear out the valid
360 * bits. This would prevent bogus_page
361 * replacement from working properly.
363 * NOTE: We do not want to clear the dirty
364 * bit for a partial DEV_BSIZE'd truncation!
365 * This is DEV_BSIZE aligned!
367 n = ((base + DEV_BMASK) & ~DEV_BMASK) - base;
371 vm_page_set_validclean(m, base, size);
373 m->dirty = VM_PAGE_BITS_ALL;
378 vp->v_filesize = nsize;
383 * Release a page busied for a getpages operation. The page may have become
384 * wired (typically due to being used by the buffer cache) or otherwise been
385 * soft-busied and cannot be freed in that case. A held page can still be
389 vnode_pager_freepage(vm_page_t m)
391 if (m->busy || m->wire_count) {
400 * EOPNOTSUPP is no longer legal. For local media VFS's that do not
401 * implement their own VOP_GETPAGES, their VOP_GETPAGES should call to
402 * vnode_pager_generic_getpages() to implement the previous behaviour.
404 * All other FS's should use the bypass to get to the local media
405 * backing vp's VOP_GETPAGES.
408 vnode_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
412 int bytes = count * PAGE_SIZE;
415 rtval = VOP_GETPAGES(vp, m, bytes, reqpage, 0);
416 if (rtval == EOPNOTSUPP)
417 panic("vnode_pager: vfs's must implement vop_getpages\n");
422 * This is now called from local media FS's to operate against their
423 * own vnodes if they fail to implement VOP_GETPAGES.
425 * With all the caching local media devices do these days there is really
426 * very little point to attempting to restrict the I/O size to contiguous
427 * blocks on-disk, especially if our caller thinks we need all the specified
428 * pages. Just construct and issue a READ.
431 vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int bytecount,
443 * Do not do anything if the vnode is bad.
445 if (vp->v_mount == NULL)
449 * Calculate the number of pages. Since we are paging in whole
450 * pages, adjust bytecount to be an integral multiple of the page
451 * size. It will be clipped to the file EOF later on.
453 bytecount = round_page(bytecount);
454 count = bytecount / PAGE_SIZE;
457 * If we have a completely valid page available to us, we can
458 * clean up and return. Otherwise we have to re-read the
461 * Note that this does not work with NFS, so NFS has its own
462 * getpages routine. The problem is that NFS can have partially
463 * valid pages associated with the buffer cache due to the piecemeal
464 * write support. If we were to fall through and re-read the media
465 * as we do here, dirty data could be lost.
467 if (m[reqpage]->valid == VM_PAGE_BITS_ALL) {
468 for (i = 0; i < count; i++) {
470 vnode_pager_freepage(m[i]);
476 * Discard pages past the file EOF. If the requested page is past
477 * the file EOF we just leave its valid bits set to 0, the caller
478 * expects to maintain ownership of the requested page. If the
479 * entire range is past file EOF discard everything and generate
482 foff = IDX_TO_OFF(m[0]->pindex);
483 if (foff >= vp->v_filesize) {
484 for (i = 0; i < count; i++) {
486 vnode_pager_freepage(m[i]);
488 return VM_PAGER_ERROR;
491 if (foff + bytecount > vp->v_filesize) {
492 bytecount = vp->v_filesize - foff;
493 i = round_page(bytecount) / PAGE_SIZE;
496 if (count != reqpage)
497 vnode_pager_freepage(m[count]);
502 * The size of the transfer is bytecount. bytecount will be an
503 * integral multiple of the page size unless it has been clipped
504 * to the file EOF. The transfer cannot exceed the file EOF.
506 * When dealing with real devices we must round-up to the device
509 if (vp->v_type == VBLK || vp->v_type == VCHR) {
510 int secmask = vp->v_rdev->si_bsize_phys - 1;
511 KASSERT(secmask < PAGE_SIZE, ("vnode_pager_generic_getpages: sector size %d too large\n", secmask + 1));
512 bytecount = (bytecount + secmask) & ~secmask;
516 * Severe hack to avoid deadlocks with the buffer cache
518 for (i = 0; i < count; ++i) {
521 vm_page_io_start(mt);
526 * Issue the I/O without any read-ahead
529 /*ioflags |= IO_SEQMAX << IO_SEQSHIFT;*/
531 aiov.iov_base = (caddr_t) 0;
532 aiov.iov_len = bytecount;
533 auio.uio_iov = &aiov;
535 auio.uio_offset = foff;
536 auio.uio_segflg = UIO_NOCOPY;
537 auio.uio_rw = UIO_READ;
538 auio.uio_resid = bytecount;
540 mycpu->gd_cnt.v_vnodein++;
541 mycpu->gd_cnt.v_vnodepgsin += count;
543 error = VOP_READ(vp, &auio, ioflags, proc0.p_ucred);
546 * Severe hack to avoid deadlocks with the buffer cache
548 for (i = 0; i < count; ++i) {
551 while (vm_page_sleep_busy(mt, FALSE, "getpgs"))
554 vm_page_io_finish(mt);
558 * Calculate the actual number of bytes read and clean up the
561 bytecount -= auio.uio_resid;
563 for (i = 0; i < count; ++i) {
567 if (error == 0 && mt->valid) {
568 if (mt->flags & PG_WANTED)
569 vm_page_activate(mt);
571 vm_page_deactivate(mt);
574 vnode_pager_freepage(mt);
576 } else if (mt->valid == 0) {
578 kprintf("page failed but no I/O error page %p object %p pindex %d\n", mt, mt->object, (int) mt->pindex);
579 /* whoops, something happened */
582 } else if (mt->valid != VM_PAGE_BITS_ALL) {
584 * Zero-extend the requested page if necessary (if
585 * the filesystem is using a small block size).
587 vm_page_zero_invalid(mt, TRUE);
591 kprintf("vnode_pager_getpages: I/O read error\n");
593 return (error ? VM_PAGER_ERROR : VM_PAGER_OK);
597 * EOPNOTSUPP is no longer legal. For local media VFS's that do not
598 * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to
599 * vnode_pager_generic_putpages() to implement the previous behaviour.
601 * All other FS's should use the bypass to get to the local media
602 * backing vp's VOP_PUTPAGES.
605 vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count,
606 boolean_t sync, int *rtvals)
610 int bytes = count * PAGE_SIZE;
613 * Force synchronous operation if we are extremely low on memory
614 * to prevent a low-memory deadlock. VOP operations often need to
615 * allocate more memory to initiate the I/O ( i.e. do a BMAP
616 * operation ). The swapper handles the case by limiting the amount
617 * of asynchronous I/O, but that sort of solution doesn't scale well
618 * for the vnode pager without a lot of work.
620 * Also, the backing vnode's iodone routine may not wake the pageout
621 * daemon up. This should be probably be addressed XXX.
624 if ((vmstats.v_free_count + vmstats.v_cache_count) < vmstats.v_pageout_free_min)
628 * Call device-specific putpages function
632 rtval = VOP_PUTPAGES(vp, m, bytes, sync, rtvals, 0);
633 if (rtval == EOPNOTSUPP) {
634 kprintf("vnode_pager: *** WARNING *** stale FS putpages\n");
635 rtval = vnode_pager_generic_putpages( vp, m, bytes, sync, rtvals);
641 * This is now called from local media FS's to operate against their
642 * own vnodes if they fail to implement VOP_PUTPAGES.
644 * This is typically called indirectly via the pageout daemon and
645 * clustering has already typically occured, so in general we ask the
646 * underlying filesystem to write the data out asynchronously rather
650 vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *m, int bytecount,
651 int flags, int *rtvals)
658 vm_ooffset_t poffset;
664 object = vp->v_object;
665 count = bytecount / PAGE_SIZE;
667 for (i = 0; i < count; i++)
668 rtvals[i] = VM_PAGER_AGAIN;
670 if ((int) m[0]->pindex < 0) {
671 kprintf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%lx(%x)\n",
672 (long)m[0]->pindex, m[0]->dirty);
673 rtvals[0] = VM_PAGER_BAD;
677 maxsize = count * PAGE_SIZE;
680 poffset = IDX_TO_OFF(m[0]->pindex);
683 * If the page-aligned write is larger then the actual file we
684 * have to invalidate pages occuring beyond the file EOF. However,
685 * there is an edge case where a file may not be page-aligned where
686 * the last page is partially invalid. In this case the filesystem
687 * may not properly clear the dirty bits for the entire page (which
688 * could be VM_PAGE_BITS_ALL due to the page having been mmap()d).
689 * With the page locked we are free to fix-up the dirty bits here.
691 * We do not under any circumstances truncate the valid bits, as
692 * this will screw up bogus page replacement.
694 * The caller has already read-protected the pages. The VFS must
695 * use the buffer cache to wrap the pages. The pages might not
696 * be immediately flushed by the buffer cache but once under its
697 * control the pages themselves can wind up being marked clean
698 * and their covering buffer cache buffer can be marked dirty.
700 if (maxsize + poffset > vp->v_filesize) {
701 if (vp->v_filesize > poffset) {
704 maxsize = vp->v_filesize - poffset;
705 ncount = btoc(maxsize);
706 if ((pgoff = (int)maxsize & PAGE_MASK) != 0) {
707 vm_page_clear_dirty(m[ncount - 1], pgoff,
714 if (ncount < count) {
715 for (i = ncount; i < count; i++) {
716 rtvals[i] = VM_PAGER_BAD;
722 * pageouts are already clustered, use IO_ASYNC to force a bawrite()
723 * rather then a bdwrite() to prevent paging I/O from saturating
724 * the buffer cache. Dummy-up the sequential heuristic to cause
725 * large ranges to cluster. If neither IO_SYNC or IO_ASYNC is set,
726 * the system decides how to cluster.
729 if (flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL))
731 else if ((flags & VM_PAGER_CLUSTER_OK) == 0)
733 ioflags |= (flags & VM_PAGER_PUT_INVAL) ? IO_INVAL: 0;
734 ioflags |= IO_SEQMAX << IO_SEQSHIFT;
736 aiov.iov_base = (caddr_t) 0;
737 aiov.iov_len = maxsize;
738 auio.uio_iov = &aiov;
740 auio.uio_offset = poffset;
741 auio.uio_segflg = UIO_NOCOPY;
742 auio.uio_rw = UIO_WRITE;
743 auio.uio_resid = maxsize;
745 error = VOP_WRITE(vp, &auio, ioflags, proc0.p_ucred);
746 mycpu->gd_cnt.v_vnodeout++;
747 mycpu->gd_cnt.v_vnodepgsout += ncount;
750 krateprintf(&vbadrate,
751 "vnode_pager_putpages: I/O error %d\n", error);
753 if (auio.uio_resid) {
754 krateprintf(&vresrate,
755 "vnode_pager_putpages: residual I/O %d at %lu\n",
756 auio.uio_resid, (u_long)m[0]->pindex);
758 for (i = 0; i < ncount; i++)
759 rtvals[i] = VM_PAGER_OK;
764 vnode_pager_lock(vm_object_t object)
766 struct thread *td = curthread; /* XXX */
769 for (; object != NULL; object = object->backing_object) {
770 if (object->type != OBJT_VNODE)
772 if (object->flags & OBJ_DEAD)
776 struct vnode *vp = object->handle;
777 error = vget(vp, LK_SHARED | LK_RETRY | LK_CANRECURSE);
779 if (object->handle != vp) {
785 if ((object->flags & OBJ_DEAD) ||
786 (object->type != OBJT_VNODE)) {
789 kprintf("vnode_pager_lock: vp %p error %d lockstatus %d, retrying\n", vp, error, lockstatus(&vp->v_lock, td));
790 tsleep(object->handle, 0, "vnpgrl", hz);