2 * Copyright (c) 1998 Matthew Dillon,
3 * Copyright (c) 1994 John S. Dyson
4 * Copyright (c) 1990 University of Utah.
5 * Copyright (c) 1982, 1986, 1989, 1993
6 * The Regents of the University of California. All rights reserved.
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
43 * Radix Bitmap 'blists'.
45 * - The new swapper uses the new radix bitmap code. This should scale
46 * to arbitrarily small or arbitrarily large swap spaces and an almost
47 * arbitrary degree of fragmentation.
51 * - on the fly reallocation of swap during putpages. The new system
52 * does not try to keep previously allocated swap blocks for dirty
55 * - on the fly deallocation of swap
57 * - No more garbage collection required. Unnecessarily allocated swap
58 * blocks only exist for dirty vm_page_t's now and these are already
59 * cycled (in a high-load system) by the pager. We also do on-the-fly
60 * removal of invalidated swap blocks when a page is destroyed
63 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$
65 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94
66 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94
69 #include <sys/cdefs.h>
70 __FBSDID("$FreeBSD$");
76 #include <sys/param.h>
77 #include <sys/systm.h>
79 #include <sys/kernel.h>
84 #include <sys/fcntl.h>
85 #include <sys/mount.h>
86 #include <sys/namei.h>
87 #include <sys/vnode.h>
89 #include <sys/malloc.h>
90 #include <sys/sysctl.h>
91 #include <sys/sysproto.h>
92 #include <sys/blist.h>
95 #include <sys/vmmeter.h>
99 #include <vm/vm_map.h>
100 #include <vm/vm_kern.h>
101 #include <vm/vm_object.h>
102 #include <vm/vm_page.h>
103 #include <vm/vm_pager.h>
104 #include <vm/vm_pageout.h>
105 #include <vm/vm_param.h>
106 #include <vm/swap_pager.h>
107 #include <vm/vm_extern.h>
110 #include <geom/geom.h>
113 * SWB_NPAGES must be a power of 2. It may be set to 1, 2, 4, 8, or 16
114 * pages per allocation. We recommend you stick with the default of 8.
115 * The 16-page limit is due to the radix code (kern/subr_blist.c).
117 #ifndef MAX_PAGEOUT_CLUSTER
118 #define MAX_PAGEOUT_CLUSTER 16
121 #if !defined(SWB_NPAGES)
122 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER
126 * Piecemeal swap metadata structure. Swap is stored in a radix tree.
128 * If SWB_NPAGES is 8 and sizeof(char *) == sizeof(daddr_t), our radix
129 * is basically 8. Assuming PAGE_SIZE == 4096, one tree level represents
130 * 32K worth of data, two levels represent 256K, three levels represent
131 * 2 MBytes. This is acceptable.
133 * Overall memory utilization is about the same as the old swap structure.
135 #define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t))
136 #define SWAP_META_PAGES (SWB_NPAGES * 2)
137 #define SWAP_META_MASK (SWAP_META_PAGES - 1)
139 typedef int32_t swblk_t; /*
140 * swap offset. This is the type used to
141 * address the "virtual swap device" and
142 * therefore the maximum swap space is
147 typedef void sw_strategy_t(struct buf *bp, struct swdevt *sw);
148 typedef void sw_close_t(struct thread *td, struct swdevt *sw);
162 struct blist *sw_blist;
163 TAILQ_ENTRY(swdevt) sw_list;
164 sw_strategy_t *sw_strategy;
165 sw_close_t *sw_close;
168 #define SW_CLOSING 0x04
171 struct swblock *swb_hnext;
172 vm_object_t swb_object;
173 vm_pindex_t swb_index;
175 daddr_t swb_pages[SWAP_META_PAGES];
178 static struct mtx sw_dev_mtx;
179 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq);
180 static struct swdevt *swdevhd; /* Allocate from here next */
181 static int nswapdev; /* Number of swap devices */
182 int swap_pager_avail;
183 static int swdev_syscall_active = 0; /* serialize swap(on|off) */
185 static void swapdev_strategy(struct buf *, struct swdevt *sw);
187 #define SWM_FREE 0x02 /* free, period */
188 #define SWM_POP 0x04 /* pop out */
190 int swap_pager_full = 2; /* swap space exhaustion (task killing) */
191 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/
192 static int nsw_rcount; /* free read buffers */
193 static int nsw_wcount_sync; /* limit write buffers / synchronous */
194 static int nsw_wcount_async; /* limit write buffers / asynchronous */
195 static int nsw_wcount_async_max;/* assigned maximum */
196 static int nsw_cluster_max; /* maximum VOP I/O allowed */
198 static struct swblock **swhash;
199 static int swhash_mask;
200 static struct mtx swhash_mtx;
202 static int swap_async_max = 4; /* maximum in-progress async I/O's */
203 static struct sx sw_alloc_sx;
206 SYSCTL_INT(_vm, OID_AUTO, swap_async_max,
207 CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops");
210 * "named" and "unnamed" anon region objects. Try to reduce the overhead
211 * of searching a named list by hashing it just a little.
216 #define NOBJLIST(handle) \
217 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)])
219 static struct mtx sw_alloc_mtx; /* protect list manipulation */
220 static struct pagerlst swap_pager_object_list[NOBJLISTS];
221 static uma_zone_t swap_zone;
222 static struct vm_object swap_zone_obj;
225 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure
226 * calls hooked from other parts of the VM system and do not appear here.
227 * (see vm/swap_pager.h).
230 swap_pager_alloc(void *handle, vm_ooffset_t size,
231 vm_prot_t prot, vm_ooffset_t offset);
232 static void swap_pager_dealloc(vm_object_t object);
233 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int);
234 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *);
236 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after);
237 static void swap_pager_init(void);
238 static void swap_pager_unswapped(vm_page_t);
239 static void swap_pager_swapoff(struct swdevt *sp);
241 struct pagerops swappagerops = {
242 .pgo_init = swap_pager_init, /* early system initialization of pager */
243 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */
244 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */
245 .pgo_getpages = swap_pager_getpages, /* pagein */
246 .pgo_putpages = swap_pager_putpages, /* pageout */
247 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */
248 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */
252 * dmmax is in page-sized chunks with the new swap system. It was
253 * dev-bsized chunks in the old. dmmax is always a power of 2.
255 * swap_*() routines are externally accessible. swp_*() routines are
259 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */
260 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */
262 SYSCTL_INT(_vm, OID_AUTO, dmmax,
263 CTLFLAG_RD, &dmmax, 0, "Maximum size of a swap block");
265 static void swp_sizecheck(void);
266 static void swp_pager_async_iodone(struct buf *bp);
267 static int swapongeom(struct thread *, struct vnode *);
268 static int swaponvp(struct thread *, struct vnode *, u_long);
269 static int swapoff_one(struct swdevt *sp, struct thread *td);
272 * Swap bitmap functions
274 static void swp_pager_freeswapspace(daddr_t blk, int npages);
275 static daddr_t swp_pager_getswapspace(int npages);
280 static struct swblock **swp_pager_hash(vm_object_t object, vm_pindex_t index);
281 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t);
282 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, daddr_t);
283 static void swp_pager_meta_free_all(vm_object_t);
284 static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int);
287 * SWP_SIZECHECK() - update swap_pager_full indication
289 * update the swap_pager_almost_full indication and warn when we are
290 * about to run out of swap space, using lowat/hiwat hysteresis.
292 * Clear swap_pager_full ( task killing ) indication when lowat is met.
294 * No restrictions on call
295 * This routine may not block.
296 * This routine must be called at splvm()
302 if (swap_pager_avail < nswap_lowat) {
303 if (swap_pager_almost_full == 0) {
304 printf("swap_pager: out of swap space\n");
305 swap_pager_almost_full = 1;
309 if (swap_pager_avail > nswap_hiwat)
310 swap_pager_almost_full = 0;
315 * SWP_PAGER_HASH() - hash swap meta data
317 * This is an helper function which hashes the swapblk given
318 * the object and page index. It returns a pointer to a pointer
319 * to the object, or a pointer to a NULL pointer if it could not
322 * This routine must be called at splvm().
324 static struct swblock **
325 swp_pager_hash(vm_object_t object, vm_pindex_t index)
327 struct swblock **pswap;
328 struct swblock *swap;
330 index &= ~(vm_pindex_t)SWAP_META_MASK;
331 pswap = &swhash[(index ^ (int)(intptr_t)object) & swhash_mask];
332 while ((swap = *pswap) != NULL) {
333 if (swap->swb_object == object &&
334 swap->swb_index == index
338 pswap = &swap->swb_hnext;
344 * SWAP_PAGER_INIT() - initialize the swap pager!
346 * Expected to be started from system init. NOTE: This code is run
347 * before much else so be careful what you depend on. Most of the VM
348 * system has yet to be initialized at this point.
351 swap_pager_init(void)
354 * Initialize object lists
358 for (i = 0; i < NOBJLISTS; ++i)
359 TAILQ_INIT(&swap_pager_object_list[i]);
360 mtx_init(&sw_alloc_mtx, "swap_pager list", NULL, MTX_DEF);
361 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF);
364 * Device Stripe, in PAGE_SIZE'd blocks
366 dmmax = SWB_NPAGES * 2;
370 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process
372 * Expected to be started from pageout process once, prior to entering
376 swap_pager_swap_init(void)
381 * Number of in-transit swap bp operations. Don't
382 * exhaust the pbufs completely. Make sure we
383 * initialize workable values (0 will work for hysteresis
384 * but it isn't very efficient).
386 * The nsw_cluster_max is constrained by the bp->b_pages[]
387 * array (MAXPHYS/PAGE_SIZE) and our locally defined
388 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are
389 * constrained by the swap device interleave stripe size.
391 * Currently we hardwire nsw_wcount_async to 4. This limit is
392 * designed to prevent other I/O from having high latencies due to
393 * our pageout I/O. The value 4 works well for one or two active swap
394 * devices but is probably a little low if you have more. Even so,
395 * a higher value would probably generate only a limited improvement
396 * with three or four active swap devices since the system does not
397 * typically have to pageout at extreme bandwidths. We will want
398 * at least 2 per swap devices, and 4 is a pretty good value if you
399 * have one NFS swap device due to the command/ack latency over NFS.
400 * So it all works out pretty well.
402 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER);
405 nsw_rcount = (nswbuf + 1) / 2;
406 nsw_wcount_sync = (nswbuf + 3) / 4;
407 nsw_wcount_async = 4;
408 nsw_wcount_async_max = nsw_wcount_async;
409 mtx_unlock(&pbuf_mtx);
412 * Initialize our zone. Right now I'm just guessing on the number
413 * we need based on the number of pages in the system. Each swblock
414 * can hold 16 pages, so this is probably overkill. This reservation
415 * is typically limited to around 32MB by default.
417 n = cnt.v_page_count / 2;
418 if (maxswzone && n > maxswzone / sizeof(struct swblock))
419 n = maxswzone / sizeof(struct swblock);
421 swap_zone = uma_zcreate("SWAPMETA", sizeof(struct swblock), NULL, NULL,
422 NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM);
423 if (swap_zone == NULL)
424 panic("failed to create swap_zone.");
426 if (uma_zone_set_obj(swap_zone, &swap_zone_obj, n))
429 * if the allocation failed, try a zone two thirds the
430 * size of the previous attempt.
435 printf("Swap zone entries reduced from %d to %d.\n", n2, n);
439 * Initialize our meta-data hash table. The swapper does not need to
440 * be quite as efficient as the VM system, so we do not use an
441 * oversized hash table.
443 * n: size of hash table, must be power of 2
444 * swhash_mask: hash table index mask
446 for (n = 1; n < n2 / 8; n *= 2)
448 swhash = malloc(sizeof(struct swblock *) * n, M_VMPGDATA, M_WAITOK | M_ZERO);
450 mtx_init(&swhash_mtx, "swap_pager swhash", NULL, MTX_DEF);
454 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate
455 * its metadata structures.
457 * This routine is called from the mmap and fork code to create a new
458 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object
459 * and then converting it with swp_pager_meta_build().
461 * This routine may block in vm_object_allocate() and create a named
462 * object lookup race, so we must interlock. We must also run at
463 * splvm() for the object lookup to handle races with interrupts, but
464 * we do not have to maintain splvm() in between the lookup and the
465 * add because (I believe) it is not possible to attempt to create
466 * a new swap object w/handle when a default object with that handle
472 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
478 pindex = OFF_TO_IDX(offset + PAGE_MASK + size);
483 * Reference existing named region or allocate new one. There
484 * should not be a race here against swp_pager_meta_build()
485 * as called from vm_page_remove() in regards to the lookup
488 sx_xlock(&sw_alloc_sx);
489 object = vm_pager_object_lookup(NOBJLIST(handle), handle);
491 if (object != NULL) {
492 vm_object_reference(object);
494 object = vm_object_allocate(OBJT_DEFAULT, pindex);
495 object->handle = handle;
497 VM_OBJECT_LOCK(object);
498 swp_pager_meta_build(object, 0, SWAPBLK_NONE);
499 VM_OBJECT_UNLOCK(object);
501 sx_xunlock(&sw_alloc_sx);
504 object = vm_object_allocate(OBJT_DEFAULT, pindex);
506 VM_OBJECT_LOCK(object);
507 swp_pager_meta_build(object, 0, SWAPBLK_NONE);
508 VM_OBJECT_UNLOCK(object);
514 * SWAP_PAGER_DEALLOC() - remove swap metadata from object
516 * The swap backing for the object is destroyed. The code is
517 * designed such that we can reinstantiate it later, but this
518 * routine is typically called only when the entire object is
519 * about to be destroyed.
521 * This routine may block, but no longer does.
523 * The object must be locked or unreferenceable.
526 swap_pager_dealloc(vm_object_t object)
530 * Remove from list right away so lookups will fail if we block for
531 * pageout completion.
533 if (object->handle != NULL) {
534 mtx_lock(&sw_alloc_mtx);
535 TAILQ_REMOVE(NOBJLIST(object->handle), object, pager_object_list);
536 mtx_unlock(&sw_alloc_mtx);
539 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
540 vm_object_pip_wait(object, "swpdea");
543 * Free all remaining metadata. We only bother to free it from
544 * the swap meta data. We do not attempt to free swapblk's still
545 * associated with vm_page_t's for this object. We do not care
546 * if paging is still in progress on some objects.
548 swp_pager_meta_free_all(object);
551 /************************************************************************
552 * SWAP PAGER BITMAP ROUTINES *
553 ************************************************************************/
556 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space
558 * Allocate swap for the requested number of pages. The starting
559 * swap block number (a page index) is returned or SWAPBLK_NONE
560 * if the allocation failed.
562 * Also has the side effect of advising that somebody made a mistake
563 * when they configured swap and didn't configure enough.
565 * Must be called at splvm() to avoid races with bitmap frees from
566 * vm_page_remove() aka swap_pager_page_removed().
568 * This routine may not block
569 * This routine must be called at splvm().
571 * We allocate in round-robin fashion from the configured devices.
574 swp_pager_getswapspace(int npages)
581 mtx_lock(&sw_dev_mtx);
583 for (i = 0; i < nswapdev; i++) {
585 sp = TAILQ_FIRST(&swtailq);
586 if (!(sp->sw_flags & SW_CLOSING)) {
587 blk = blist_alloc(sp->sw_blist, npages);
588 if (blk != SWAPBLK_NONE) {
590 sp->sw_used += npages;
591 swap_pager_avail -= npages;
593 swdevhd = TAILQ_NEXT(sp, sw_list);
597 sp = TAILQ_NEXT(sp, sw_list);
599 if (swap_pager_full != 2) {
600 printf("swap_pager_getswapspace(%d): failed\n", npages);
602 swap_pager_almost_full = 1;
606 mtx_unlock(&sw_dev_mtx);
611 swp_pager_isondev(daddr_t blk, struct swdevt *sp)
614 return (blk >= sp->sw_first && blk < sp->sw_end);
618 swp_pager_strategy(struct buf *bp)
622 mtx_lock(&sw_dev_mtx);
623 TAILQ_FOREACH(sp, &swtailq, sw_list) {
624 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) {
625 mtx_unlock(&sw_dev_mtx);
626 sp->sw_strategy(bp, sp);
630 panic("Swapdev not found");
635 * SWP_PAGER_FREESWAPSPACE() - free raw swap space
637 * This routine returns the specified swap blocks back to the bitmap.
639 * Note: This routine may not block (it could in the old swap code),
640 * and through the use of the new blist routines it does not block.
642 * We must be called at splvm() to avoid races with bitmap frees from
643 * vm_page_remove() aka swap_pager_page_removed().
645 * This routine may not block
646 * This routine must be called at splvm().
649 swp_pager_freeswapspace(daddr_t blk, int npages)
653 mtx_lock(&sw_dev_mtx);
654 TAILQ_FOREACH(sp, &swtailq, sw_list) {
655 if (blk >= sp->sw_first && blk < sp->sw_end) {
656 sp->sw_used -= npages;
658 * If we are attempting to stop swapping on
659 * this device, we don't want to mark any
660 * blocks free lest they be reused.
662 if ((sp->sw_flags & SW_CLOSING) == 0) {
663 blist_free(sp->sw_blist, blk - sp->sw_first,
665 swap_pager_avail += npages;
668 mtx_unlock(&sw_dev_mtx);
672 panic("Swapdev not found");
676 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page
677 * range within an object.
679 * This is a globally accessible routine.
681 * This routine removes swapblk assignments from swap metadata.
683 * The external callers of this routine typically have already destroyed
684 * or renamed vm_page_t's associated with this range in the object so
687 * This routine may be called at any spl. We up our spl to splvm temporarily
688 * in order to perform the metadata removal.
691 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size)
694 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
695 swp_pager_meta_free(object, start, size);
699 * SWAP_PAGER_RESERVE() - reserve swap blocks in object
701 * Assigns swap blocks to the specified range within the object. The
702 * swap blocks are not zerod. Any previous swap assignment is destroyed.
704 * Returns 0 on success, -1 on failure.
707 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size)
710 daddr_t blk = SWAPBLK_NONE;
711 vm_pindex_t beg = start; /* save start index */
713 VM_OBJECT_LOCK(object);
717 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) {
720 swp_pager_meta_free(object, beg, start - beg);
721 VM_OBJECT_UNLOCK(object);
726 swp_pager_meta_build(object, start, blk);
732 swp_pager_meta_free(object, start, n);
733 VM_OBJECT_UNLOCK(object);
738 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager
739 * and destroy the source.
741 * Copy any valid swapblks from the source to the destination. In
742 * cases where both the source and destination have a valid swapblk,
743 * we keep the destination's.
745 * This routine is allowed to block. It may block allocating metadata
746 * indirectly through swp_pager_meta_build() or if paging is still in
747 * progress on the source.
749 * This routine can be called at any spl
751 * XXX vm_page_collapse() kinda expects us not to block because we
752 * supposedly do not need to allocate memory, but for the moment we
753 * *may* have to get a little memory from the zone allocator, but
754 * it is taken from the interrupt memory. We should be ok.
756 * The source object contains no vm_page_t's (which is just as well)
758 * The source object is of type OBJT_SWAP.
760 * The source and destination objects must be locked or
761 * inaccessible (XXX are they ?)
764 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
765 vm_pindex_t offset, int destroysource)
769 VM_OBJECT_LOCK_ASSERT(srcobject, MA_OWNED);
770 VM_OBJECT_LOCK_ASSERT(dstobject, MA_OWNED);
773 * If destroysource is set, we remove the source object from the
774 * swap_pager internal queue now.
777 if (srcobject->handle != NULL) {
778 mtx_lock(&sw_alloc_mtx);
780 NOBJLIST(srcobject->handle),
784 mtx_unlock(&sw_alloc_mtx);
789 * transfer source to destination.
791 for (i = 0; i < dstobject->size; ++i) {
795 * Locate (without changing) the swapblk on the destination,
796 * unless it is invalid in which case free it silently, or
797 * if the destination is a resident page, in which case the
798 * source is thrown away.
800 dstaddr = swp_pager_meta_ctl(dstobject, i, 0);
802 if (dstaddr == SWAPBLK_NONE) {
804 * Destination has no swapblk and is not resident,
809 srcaddr = swp_pager_meta_ctl(
815 if (srcaddr != SWAPBLK_NONE) {
817 * swp_pager_meta_build() can sleep.
819 vm_object_pip_add(srcobject, 1);
820 VM_OBJECT_UNLOCK(srcobject);
821 vm_object_pip_add(dstobject, 1);
822 swp_pager_meta_build(dstobject, i, srcaddr);
823 vm_object_pip_wakeup(dstobject);
824 VM_OBJECT_LOCK(srcobject);
825 vm_object_pip_wakeup(srcobject);
829 * Destination has valid swapblk or it is represented
830 * by a resident page. We destroy the sourceblock.
833 swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE);
838 * Free left over swap blocks in source.
840 * We have to revert the type to OBJT_DEFAULT so we do not accidently
841 * double-remove the object from the swap queues.
844 swp_pager_meta_free_all(srcobject);
846 * Reverting the type is not necessary, the caller is going
847 * to destroy srcobject directly, but I'm doing it here
848 * for consistency since we've removed the object from its
851 srcobject->type = OBJT_DEFAULT;
856 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for
857 * the requested page.
859 * We determine whether good backing store exists for the requested
860 * page and return TRUE if it does, FALSE if it doesn't.
862 * If TRUE, we also try to determine how much valid, contiguous backing
863 * store exists before and after the requested page within a reasonable
864 * distance. We do not try to restrict it to the swap device stripe
865 * (that is handled in getpages/putpages). It probably isn't worth
869 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after)
873 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
875 * do we have good backing store at the requested index ?
877 blk0 = swp_pager_meta_ctl(object, pindex, 0);
879 if (blk0 == SWAPBLK_NONE) {
888 * find backwards-looking contiguous good backing store
890 if (before != NULL) {
893 for (i = 1; i < (SWB_NPAGES/2); ++i) {
898 blk = swp_pager_meta_ctl(object, pindex - i, 0);
906 * find forward-looking contiguous good backing store
911 for (i = 1; i < (SWB_NPAGES/2); ++i) {
914 blk = swp_pager_meta_ctl(object, pindex + i, 0);
924 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page
926 * This removes any associated swap backing store, whether valid or
927 * not, from the page.
929 * This routine is typically called when a page is made dirty, at
930 * which point any associated swap can be freed. MADV_FREE also
931 * calls us in a special-case situation
933 * NOTE!!! If the page is clean and the swap was valid, the caller
934 * should make the page dirty before calling this routine. This routine
935 * does NOT change the m->dirty status of the page. Also: MADV_FREE
938 * This routine may not block
939 * This routine must be called at splvm()
942 swap_pager_unswapped(vm_page_t m)
945 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
946 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE);
950 * SWAP_PAGER_GETPAGES() - bring pages in from swap
952 * Attempt to retrieve (m, count) pages from backing store, but make
953 * sure we retrieve at least m[reqpage]. We try to load in as large
954 * a chunk surrounding m[reqpage] as is contiguous in swap and which
955 * belongs to the same object.
957 * The code is designed for asynchronous operation and
958 * immediate-notification of 'reqpage' but tends not to be
959 * used that way. Please do not optimize-out this algorithmic
960 * feature, I intend to improve on it in the future.
962 * The parent has a single vm_object_pip_add() reference prior to
963 * calling us and we should return with the same.
965 * The parent has BUSY'd the pages. We should return with 'm'
966 * left busy, but the others adjusted.
969 swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
979 KASSERT(mreq->object == object,
980 ("swap_pager_getpages: object mismatch %p/%p",
981 object, mreq->object));
984 * Calculate range to retrieve. The pages have already been assigned
985 * their swapblks. We require a *contiguous* range but we know it to
986 * not span devices. If we do not supply it, bad things
987 * happen. Note that blk, iblk & jblk can be SWAPBLK_NONE, but the
988 * loops are set up such that the case(s) are handled implicitly.
990 * The swp_*() calls must be made at splvm(). vm_page_free() does
991 * not need to be, but it will go a little faster if it is.
993 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0);
995 for (i = reqpage - 1; i >= 0; --i) {
998 iblk = swp_pager_meta_ctl(m[i]->object, m[i]->pindex, 0);
999 if (blk != iblk + (reqpage - i))
1004 for (j = reqpage + 1; j < count; ++j) {
1007 jblk = swp_pager_meta_ctl(m[j]->object, m[j]->pindex, 0);
1008 if (blk != jblk - (j - reqpage))
1013 * free pages outside our collection range. Note: we never free
1014 * mreq, it must remain busy throughout.
1016 if (0 < i || j < count) {
1019 vm_page_lock_queues();
1020 for (k = 0; k < i; ++k)
1022 for (k = j; k < count; ++k)
1024 vm_page_unlock_queues();
1028 * Return VM_PAGER_FAIL if we have nothing to do. Return mreq
1029 * still busy, but the others unbusied.
1031 if (blk == SWAPBLK_NONE)
1032 return (VM_PAGER_FAIL);
1035 * Getpbuf() can sleep.
1037 VM_OBJECT_UNLOCK(object);
1039 * Get a swap buffer header to perform the IO
1041 bp = getpbuf(&nsw_rcount);
1042 bp->b_flags |= B_PAGING;
1045 * map our page(s) into kva for input
1047 pmap_qenter((vm_offset_t)bp->b_data, m + i, j - i);
1049 bp->b_iocmd = BIO_READ;
1050 bp->b_iodone = swp_pager_async_iodone;
1051 bp->b_rcred = crhold(thread0.td_ucred);
1052 bp->b_wcred = crhold(thread0.td_ucred);
1053 bp->b_blkno = blk - (reqpage - i);
1054 bp->b_bcount = PAGE_SIZE * (j - i);
1055 bp->b_bufsize = PAGE_SIZE * (j - i);
1056 bp->b_pager.pg_reqpage = reqpage - i;
1058 VM_OBJECT_LOCK(object);
1062 for (k = i; k < j; ++k) {
1063 bp->b_pages[k - i] = m[k];
1064 m[k]->oflags |= VPO_SWAPINPROG;
1067 bp->b_npages = j - i;
1070 cnt.v_swappgsin += bp->b_npages;
1073 * We still hold the lock on mreq, and our automatic completion routine
1074 * does not remove it.
1076 vm_object_pip_add(object, bp->b_npages);
1077 VM_OBJECT_UNLOCK(object);
1080 * perform the I/O. NOTE!!! bp cannot be considered valid after
1081 * this point because we automatically release it on completion.
1082 * Instead, we look at the one page we are interested in which we
1083 * still hold a lock on even through the I/O completion.
1085 * The other pages in our m[] array are also released on completion,
1086 * so we cannot assume they are valid anymore either.
1088 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1091 swp_pager_strategy(bp);
1094 * wait for the page we want to complete. VPO_SWAPINPROG is always
1095 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE
1096 * is set in the meta-data.
1098 VM_OBJECT_LOCK(object);
1099 while ((mreq->oflags & VPO_SWAPINPROG) != 0) {
1100 mreq->oflags |= VPO_WANTED;
1101 vm_page_lock_queues();
1102 vm_page_flag_set(mreq, PG_REFERENCED);
1103 vm_page_unlock_queues();
1105 if (msleep(mreq, VM_OBJECT_MTX(object), PSWP, "swread", hz*20)) {
1107 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n",
1108 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount);
1113 * mreq is left busied after completion, but all the other pages
1114 * are freed. If we had an unrecoverable read error the page will
1117 if (mreq->valid != VM_PAGE_BITS_ALL) {
1118 return (VM_PAGER_ERROR);
1120 return (VM_PAGER_OK);
1124 * A final note: in a low swap situation, we cannot deallocate swap
1125 * and mark a page dirty here because the caller is likely to mark
1126 * the page clean when we return, causing the page to possibly revert
1127 * to all-zero's later.
1132 * swap_pager_putpages:
1134 * Assign swap (if necessary) and initiate I/O on the specified pages.
1136 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects
1137 * are automatically converted to SWAP objects.
1139 * In a low memory situation we may block in VOP_STRATEGY(), but the new
1140 * vm_page reservation system coupled with properly written VFS devices
1141 * should ensure that no low-memory deadlock occurs. This is an area
1144 * The parent has N vm_object_pip_add() references prior to
1145 * calling us and will remove references for rtvals[] that are
1146 * not set to VM_PAGER_PEND. We need to remove the rest on I/O
1149 * The parent has soft-busy'd the pages it passes us and will unbusy
1150 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return.
1151 * We need to unbusy the rest on I/O completion.
1154 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count,
1155 boolean_t sync, int *rtvals)
1161 if (count && m[0]->object != object) {
1162 panic("swap_pager_getpages: object mismatch %p/%p",
1171 * Turn object into OBJT_SWAP
1172 * check for bogus sysops
1173 * force sync if not pageout process
1175 if (object->type != OBJT_SWAP)
1176 swp_pager_meta_build(object, 0, SWAPBLK_NONE);
1177 VM_OBJECT_UNLOCK(object);
1179 if (curproc != pageproc)
1185 * Update nsw parameters from swap_async_max sysctl values.
1186 * Do not let the sysop crash the machine with bogus numbers.
1188 mtx_lock(&pbuf_mtx);
1189 if (swap_async_max != nsw_wcount_async_max) {
1195 if ((n = swap_async_max) > nswbuf / 2)
1202 * Adjust difference ( if possible ). If the current async
1203 * count is too low, we may not be able to make the adjustment
1206 n -= nsw_wcount_async_max;
1207 if (nsw_wcount_async + n >= 0) {
1208 nsw_wcount_async += n;
1209 nsw_wcount_async_max += n;
1210 wakeup(&nsw_wcount_async);
1213 mtx_unlock(&pbuf_mtx);
1218 * Assign swap blocks and issue I/O. We reallocate swap on the fly.
1219 * The page is left dirty until the pageout operation completes
1222 for (i = 0; i < count; i += n) {
1228 * Maximum I/O size is limited by a number of factors.
1230 n = min(BLIST_MAX_ALLOC, count - i);
1231 n = min(n, nsw_cluster_max);
1234 * Get biggest block of swap we can. If we fail, fall
1235 * back and try to allocate a smaller block. Don't go
1236 * overboard trying to allocate space if it would overly
1240 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE &&
1245 if (blk == SWAPBLK_NONE) {
1246 for (j = 0; j < n; ++j)
1247 rtvals[i+j] = VM_PAGER_FAIL;
1252 * All I/O parameters have been satisfied, build the I/O
1253 * request and assign the swap space.
1256 bp = getpbuf(&nsw_wcount_sync);
1258 bp = getpbuf(&nsw_wcount_async);
1259 bp->b_flags = B_ASYNC;
1261 bp->b_flags |= B_PAGING;
1262 bp->b_iocmd = BIO_WRITE;
1264 pmap_qenter((vm_offset_t)bp->b_data, &m[i], n);
1266 bp->b_rcred = crhold(thread0.td_ucred);
1267 bp->b_wcred = crhold(thread0.td_ucred);
1268 bp->b_bcount = PAGE_SIZE * n;
1269 bp->b_bufsize = PAGE_SIZE * n;
1272 VM_OBJECT_LOCK(object);
1273 for (j = 0; j < n; ++j) {
1274 vm_page_t mreq = m[i+j];
1276 swp_pager_meta_build(
1281 vm_page_dirty(mreq);
1282 rtvals[i+j] = VM_PAGER_OK;
1284 mreq->oflags |= VPO_SWAPINPROG;
1285 bp->b_pages[j] = mreq;
1287 VM_OBJECT_UNLOCK(object);
1290 * Must set dirty range for NFS to work.
1293 bp->b_dirtyend = bp->b_bcount;
1296 cnt.v_swappgsout += bp->b_npages;
1301 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1303 if (sync == FALSE) {
1304 bp->b_iodone = swp_pager_async_iodone;
1306 swp_pager_strategy(bp);
1308 for (j = 0; j < n; ++j)
1309 rtvals[i+j] = VM_PAGER_PEND;
1310 /* restart outter loop */
1317 * NOTE: b_blkno is destroyed by the call to swapdev_strategy
1319 bp->b_iodone = bdone;
1320 swp_pager_strategy(bp);
1323 * Wait for the sync I/O to complete, then update rtvals.
1324 * We just set the rtvals[] to VM_PAGER_PEND so we can call
1325 * our async completion routine at the end, thus avoiding a
1328 bwait(bp, PVM, "swwrt");
1329 for (j = 0; j < n; ++j)
1330 rtvals[i+j] = VM_PAGER_PEND;
1332 * Now that we are through with the bp, we can call the
1333 * normal async completion, which frees everything up.
1335 swp_pager_async_iodone(bp);
1337 VM_OBJECT_LOCK(object);
1341 * swp_pager_async_iodone:
1343 * Completion routine for asynchronous reads and writes from/to swap.
1344 * Also called manually by synchronous code to finish up a bp.
1346 * For READ operations, the pages are PG_BUSY'd. For WRITE operations,
1347 * the pages are vm_page_t->busy'd. For READ operations, we PG_BUSY
1348 * unbusy all pages except the 'main' request page. For WRITE
1349 * operations, we vm_page_t->busy'd unbusy all pages ( we can do this
1350 * because we marked them all VM_PAGER_PEND on return from putpages ).
1352 * This routine may not block.
1353 * This routine is called at splbio() or better
1355 * We up ourselves to splvm() as required for various vm_page related
1359 swp_pager_async_iodone(struct buf *bp)
1362 vm_object_t object = NULL;
1367 if (bp->b_ioflags & BIO_ERROR) {
1369 "swap_pager: I/O error - %s failed; blkno %ld,"
1370 "size %ld, error %d\n",
1371 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"),
1379 * remove the mapping for kernel virtual
1381 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages);
1384 object = bp->b_pages[0]->object;
1385 VM_OBJECT_LOCK(object);
1387 vm_page_lock_queues();
1389 * cleanup pages. If an error occurs writing to swap, we are in
1390 * very serious trouble. If it happens to be a disk error, though,
1391 * we may be able to recover by reassigning the swap later on. So
1392 * in this case we remove the m->swapblk assignment for the page
1393 * but do not free it in the rlist. The errornous block(s) are thus
1394 * never reallocated as swap. Redirty the page and continue.
1396 for (i = 0; i < bp->b_npages; ++i) {
1397 vm_page_t m = bp->b_pages[i];
1399 m->oflags &= ~VPO_SWAPINPROG;
1401 if (bp->b_ioflags & BIO_ERROR) {
1403 * If an error occurs I'd love to throw the swapblk
1404 * away without freeing it back to swapspace, so it
1405 * can never be used again. But I can't from an
1408 if (bp->b_iocmd == BIO_READ) {
1410 * When reading, reqpage needs to stay
1411 * locked for the parent, but all other
1412 * pages can be freed. We still want to
1413 * wakeup the parent waiting on the page,
1414 * though. ( also: pg_reqpage can be -1 and
1415 * not match anything ).
1417 * We have to wake specifically requested pages
1418 * up too because we cleared VPO_SWAPINPROG and
1419 * someone may be waiting for that.
1421 * NOTE: for reads, m->dirty will probably
1422 * be overridden by the original caller of
1423 * getpages so don't play cute tricks here.
1426 if (i != bp->b_pager.pg_reqpage)
1431 * If i == bp->b_pager.pg_reqpage, do not wake
1432 * the page up. The caller needs to.
1436 * If a write error occurs, reactivate page
1437 * so it doesn't clog the inactive list,
1438 * then finish the I/O.
1441 vm_page_activate(m);
1442 vm_page_io_finish(m);
1444 } else if (bp->b_iocmd == BIO_READ) {
1446 * For read success, clear dirty bits. Nobody should
1447 * have this page mapped but don't take any chances,
1448 * make sure the pmap modify bits are also cleared.
1450 * NOTE: for reads, m->dirty will probably be
1451 * overridden by the original caller of getpages so
1452 * we cannot set them in order to free the underlying
1453 * swap in a low-swap situation. I don't think we'd
1454 * want to do that anyway, but it was an optimization
1455 * that existed in the old swapper for a time before
1456 * it got ripped out due to precisely this problem.
1458 * If not the requested page then deactivate it.
1460 * Note that the requested page, reqpage, is left
1461 * busied, but we still have to wake it up. The
1462 * other pages are released (unbusied) by
1463 * vm_page_wakeup(). We do not set reqpage's
1464 * valid bits here, it is up to the caller.
1466 pmap_clear_modify(m);
1467 m->valid = VM_PAGE_BITS_ALL;
1471 * We have to wake specifically requested pages
1472 * up too because we cleared VPO_SWAPINPROG and
1473 * could be waiting for it in getpages. However,
1474 * be sure to not unbusy getpages specifically
1475 * requested page - getpages expects it to be
1478 if (i != bp->b_pager.pg_reqpage) {
1479 vm_page_deactivate(m);
1486 * For write success, clear the modify and dirty
1487 * status, then finish the I/O ( which decrements the
1488 * busy count and possibly wakes waiter's up ).
1490 pmap_clear_modify(m);
1492 vm_page_io_finish(m);
1493 if (vm_page_count_severe())
1494 vm_page_try_to_cache(m);
1497 vm_page_unlock_queues();
1500 * adjust pip. NOTE: the original parent may still have its own
1501 * pip refs on the object.
1503 if (object != NULL) {
1504 vm_object_pip_wakeupn(object, bp->b_npages);
1505 VM_OBJECT_UNLOCK(object);
1509 * swapdev_strategy() manually sets b_vp and b_bufobj before calling
1510 * bstrategy(). Set them back to NULL now we're done with it, or we'll
1511 * trigger a KASSERT in relpbuf().
1515 bp->b_bufobj = NULL;
1518 * release the physical I/O buffer
1522 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount :
1523 ((bp->b_flags & B_ASYNC) ?
1532 * swap_pager_isswapped:
1534 * Return 1 if at least one page in the given object is paged
1535 * out to the given swap device.
1537 * This routine may not block.
1540 swap_pager_isswapped(vm_object_t object, struct swdevt *sp)
1546 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1547 if (object->type != OBJT_SWAP)
1550 mtx_lock(&swhash_mtx);
1551 for (bcount = 0; bcount < object->un_pager.swp.swp_bcount; bcount++) {
1552 struct swblock *swap;
1554 if ((swap = *swp_pager_hash(object, index)) != NULL) {
1555 for (i = 0; i < SWAP_META_PAGES; ++i) {
1556 if (swp_pager_isondev(swap->swb_pages[i], sp)) {
1557 mtx_unlock(&swhash_mtx);
1562 index += SWAP_META_PAGES;
1563 if (index > 0x20000000)
1564 panic("swap_pager_isswapped: failed to locate all swap meta blocks");
1566 mtx_unlock(&swhash_mtx);
1571 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in
1573 * This routine dissociates the page at the given index within a
1574 * swap block from its backing store, paging it in if necessary.
1575 * If the page is paged in, it is placed in the inactive queue,
1576 * since it had its backing store ripped out from under it.
1577 * We also attempt to swap in all other pages in the swap block,
1578 * we only guarantee that the one at the specified index is
1581 * XXX - The code to page the whole block in doesn't work, so we
1582 * revert to the one-by-one behavior for now. Sigh.
1585 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex)
1589 vm_object_pip_add(object, 1);
1590 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL|VM_ALLOC_RETRY);
1591 if (m->valid == VM_PAGE_BITS_ALL) {
1592 vm_object_pip_subtract(object, 1);
1593 vm_page_lock_queues();
1594 vm_page_activate(m);
1597 vm_page_unlock_queues();
1598 vm_pager_page_unswapped(m);
1602 if (swap_pager_getpages(object, &m, 1, 0) != VM_PAGER_OK)
1603 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/
1604 vm_object_pip_subtract(object, 1);
1605 vm_page_lock_queues();
1607 vm_page_dontneed(m);
1609 vm_page_unlock_queues();
1610 vm_pager_page_unswapped(m);
1614 * swap_pager_swapoff:
1616 * Page in all of the pages that have been paged out to the
1617 * given device. The corresponding blocks in the bitmap must be
1618 * marked as allocated and the device must be flagged SW_CLOSING.
1619 * There may be no processes swapped out to the device.
1621 * This routine may block.
1624 swap_pager_swapoff(struct swdevt *sp)
1626 struct swblock *swap;
1633 mtx_lock(&swhash_mtx);
1634 for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */
1636 for (swap = swhash[i]; swap != NULL; swap = swap->swb_hnext) {
1637 vm_object_t object = swap->swb_object;
1638 vm_pindex_t pindex = swap->swb_index;
1639 for (j = 0; j < SWAP_META_PAGES; ++j) {
1640 if (swp_pager_isondev(swap->swb_pages[j], sp)) {
1641 /* avoid deadlock */
1642 if (!VM_OBJECT_TRYLOCK(object)) {
1645 mtx_unlock(&swhash_mtx);
1646 swp_pager_force_pagein(object,
1648 VM_OBJECT_UNLOCK(object);
1649 mtx_lock(&swhash_mtx);
1656 mtx_unlock(&swhash_mtx);
1660 * Objects may be locked or paging to the device being
1661 * removed, so we will miss their pages and need to
1662 * make another pass. We have marked this device as
1663 * SW_CLOSING, so the activity should finish soon.
1666 if (retries > 100) {
1667 panic("swapoff: failed to locate %d swap blocks",
1670 tsleep(&dummy, PVM, "swpoff", hz / 20);
1675 /************************************************************************
1677 ************************************************************************
1679 * These routines manipulate the swap metadata stored in the
1680 * OBJT_SWAP object. All swp_*() routines must be called at
1681 * splvm() because swap can be freed up by the low level vm_page
1682 * code which might be called from interrupts beyond what splbio() covers.
1684 * Swap metadata is implemented with a global hash and not directly
1685 * linked into the object. Instead the object simply contains
1686 * appropriate tracking counters.
1690 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object
1692 * We first convert the object to a swap object if it is a default
1695 * The specified swapblk is added to the object's swap metadata. If
1696 * the swapblk is not valid, it is freed instead. Any previously
1697 * assigned swapblk is freed.
1699 * This routine must be called at splvm(), except when used to convert
1700 * an OBJT_DEFAULT object into an OBJT_SWAP object.
1703 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk)
1705 struct swblock *swap;
1706 struct swblock **pswap;
1709 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1711 * Convert default object to swap object if necessary
1713 if (object->type != OBJT_SWAP) {
1714 object->type = OBJT_SWAP;
1715 object->un_pager.swp.swp_bcount = 0;
1717 if (object->handle != NULL) {
1718 mtx_lock(&sw_alloc_mtx);
1720 NOBJLIST(object->handle),
1724 mtx_unlock(&sw_alloc_mtx);
1729 * Locate hash entry. If not found create, but if we aren't adding
1730 * anything just return. If we run out of space in the map we wait
1731 * and, since the hash table may have changed, retry.
1734 mtx_lock(&swhash_mtx);
1735 pswap = swp_pager_hash(object, pindex);
1737 if ((swap = *pswap) == NULL) {
1740 if (swapblk == SWAPBLK_NONE)
1743 swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT);
1745 mtx_unlock(&swhash_mtx);
1746 VM_OBJECT_UNLOCK(object);
1748 VM_OBJECT_LOCK(object);
1752 swap->swb_hnext = NULL;
1753 swap->swb_object = object;
1754 swap->swb_index = pindex & ~(vm_pindex_t)SWAP_META_MASK;
1755 swap->swb_count = 0;
1757 ++object->un_pager.swp.swp_bcount;
1759 for (i = 0; i < SWAP_META_PAGES; ++i)
1760 swap->swb_pages[i] = SWAPBLK_NONE;
1764 * Delete prior contents of metadata
1766 idx = pindex & SWAP_META_MASK;
1768 if (swap->swb_pages[idx] != SWAPBLK_NONE) {
1769 swp_pager_freeswapspace(swap->swb_pages[idx], 1);
1774 * Enter block into metadata
1776 swap->swb_pages[idx] = swapblk;
1777 if (swapblk != SWAPBLK_NONE)
1780 mtx_unlock(&swhash_mtx);
1784 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata
1786 * The requested range of blocks is freed, with any associated swap
1787 * returned to the swap bitmap.
1789 * This routine will free swap metadata structures as they are cleaned
1790 * out. This routine does *NOT* operate on swap metadata associated
1791 * with resident pages.
1793 * This routine must be called at splvm()
1796 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count)
1799 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1800 if (object->type != OBJT_SWAP)
1804 struct swblock **pswap;
1805 struct swblock *swap;
1807 mtx_lock(&swhash_mtx);
1808 pswap = swp_pager_hash(object, index);
1810 if ((swap = *pswap) != NULL) {
1811 daddr_t v = swap->swb_pages[index & SWAP_META_MASK];
1813 if (v != SWAPBLK_NONE) {
1814 swp_pager_freeswapspace(v, 1);
1815 swap->swb_pages[index & SWAP_META_MASK] =
1817 if (--swap->swb_count == 0) {
1818 *pswap = swap->swb_hnext;
1819 uma_zfree(swap_zone, swap);
1820 --object->un_pager.swp.swp_bcount;
1826 int n = SWAP_META_PAGES - (index & SWAP_META_MASK);
1830 mtx_unlock(&swhash_mtx);
1835 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object
1837 * This routine locates and destroys all swap metadata associated with
1840 * This routine must be called at splvm()
1843 swp_pager_meta_free_all(vm_object_t object)
1847 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1848 if (object->type != OBJT_SWAP)
1851 while (object->un_pager.swp.swp_bcount) {
1852 struct swblock **pswap;
1853 struct swblock *swap;
1855 mtx_lock(&swhash_mtx);
1856 pswap = swp_pager_hash(object, index);
1857 if ((swap = *pswap) != NULL) {
1860 for (i = 0; i < SWAP_META_PAGES; ++i) {
1861 daddr_t v = swap->swb_pages[i];
1862 if (v != SWAPBLK_NONE) {
1864 swp_pager_freeswapspace(v, 1);
1867 if (swap->swb_count != 0)
1868 panic("swap_pager_meta_free_all: swb_count != 0");
1869 *pswap = swap->swb_hnext;
1870 uma_zfree(swap_zone, swap);
1871 --object->un_pager.swp.swp_bcount;
1873 mtx_unlock(&swhash_mtx);
1874 index += SWAP_META_PAGES;
1875 if (index > 0x20000000)
1876 panic("swp_pager_meta_free_all: failed to locate all swap meta blocks");
1881 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data.
1883 * This routine is capable of looking up, popping, or freeing
1884 * swapblk assignments in the swap meta data or in the vm_page_t.
1885 * The routine typically returns the swapblk being looked-up, or popped,
1886 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block
1887 * was invalid. This routine will automatically free any invalid
1888 * meta-data swapblks.
1890 * It is not possible to store invalid swapblks in the swap meta data
1891 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking.
1893 * When acting on a busy resident page and paging is in progress, we
1894 * have to wait until paging is complete but otherwise can act on the
1897 * This routine must be called at splvm().
1899 * SWM_FREE remove and free swap block from metadata
1900 * SWM_POP remove from meta data but do not free.. pop it out
1903 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags)
1905 struct swblock **pswap;
1906 struct swblock *swap;
1910 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
1912 * The meta data only exists of the object is OBJT_SWAP
1913 * and even then might not be allocated yet.
1915 if (object->type != OBJT_SWAP)
1916 return (SWAPBLK_NONE);
1919 mtx_lock(&swhash_mtx);
1920 pswap = swp_pager_hash(object, pindex);
1922 if ((swap = *pswap) != NULL) {
1923 idx = pindex & SWAP_META_MASK;
1924 r1 = swap->swb_pages[idx];
1926 if (r1 != SWAPBLK_NONE) {
1927 if (flags & SWM_FREE) {
1928 swp_pager_freeswapspace(r1, 1);
1931 if (flags & (SWM_FREE|SWM_POP)) {
1932 swap->swb_pages[idx] = SWAPBLK_NONE;
1933 if (--swap->swb_count == 0) {
1934 *pswap = swap->swb_hnext;
1935 uma_zfree(swap_zone, swap);
1936 --object->un_pager.swp.swp_bcount;
1941 mtx_unlock(&swhash_mtx);
1946 * System call swapon(name) enables swapping on device name,
1947 * which must be in the swdevsw. Return EBUSY
1948 * if already swapping on this device.
1950 #ifndef _SYS_SYSPROTO_H_
1951 struct swapon_args {
1961 swapon(struct thread *td, struct swapon_args *uap)
1965 struct nameidata nd;
1973 while (swdev_syscall_active)
1974 tsleep(&swdev_syscall_active, PUSER - 1, "swpon", 0);
1975 swdev_syscall_active = 1;
1978 * Swap metadata may not fit in the KVM if we have physical
1981 if (swap_zone == NULL) {
1986 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW, UIO_USERSPACE, uap->name, td);
1991 NDFREE(&nd, NDF_ONLY_PNBUF);
1994 if (vn_isdisk(vp, &error)) {
1995 error = swapongeom(td, vp);
1996 } else if (vp->v_type == VREG &&
1997 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
1998 (error = VOP_GETATTR(vp, &attr, td->td_ucred, td)) == 0) {
2000 * Allow direct swapping to NFS regular files in the same
2001 * way that nfs_mountroot() sets up diskless swapping.
2003 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE);
2009 swdev_syscall_active = 0;
2010 wakeup_one(&swdev_syscall_active);
2017 swaponsomething(struct vnode *vp, void *id, u_long nblks, sw_strategy_t *strategy, sw_close_t *close, dev_t dev)
2019 struct swdevt *sp, *tsp;
2024 * If we go beyond this, we get overflows in the radix
2027 mblocks = 0x40000000 / BLIST_META_RADIX;
2028 if (nblks > mblocks) {
2029 printf("WARNING: reducing size to maximum of %lu blocks per swap unit\n",
2034 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
2035 * First chop nblks off to page-align it, then convert.
2037 * sw->sw_nblks is in page-sized chunks now too.
2039 nblks &= ~(ctodb(1) - 1);
2040 nblks = dbtoc(nblks);
2042 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO);
2047 sp->sw_nblks = nblks;
2049 sp->sw_strategy = strategy;
2050 sp->sw_close = close;
2052 sp->sw_blist = blist_create(nblks);
2054 * Do not free the first two block in order to avoid overwriting
2055 * any bsd label at the front of the partition
2057 blist_free(sp->sw_blist, 2, nblks - 2);
2060 mtx_lock(&sw_dev_mtx);
2061 TAILQ_FOREACH(tsp, &swtailq, sw_list) {
2062 if (tsp->sw_end >= dvbase) {
2064 * We put one uncovered page between the devices
2065 * in order to definitively prevent any cross-device
2068 dvbase = tsp->sw_end + 1;
2071 sp->sw_first = dvbase;
2072 sp->sw_end = dvbase + nblks;
2073 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list);
2075 swap_pager_avail += nblks;
2077 mtx_unlock(&sw_dev_mtx);
2081 * SYSCALL: swapoff(devname)
2083 * Disable swapping on the given device.
2085 * XXX: Badly designed system call: it should use a device index
2086 * rather than filename as specification. We keep sw_vp around
2087 * only to make this work.
2089 #ifndef _SYS_SYSPROTO_H_
2090 struct swapoff_args {
2100 swapoff(struct thread *td, struct swapoff_args *uap)
2103 struct nameidata nd;
2112 while (swdev_syscall_active)
2113 tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0);
2114 swdev_syscall_active = 1;
2116 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, td);
2120 NDFREE(&nd, NDF_ONLY_PNBUF);
2123 mtx_lock(&sw_dev_mtx);
2124 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2125 if (sp->sw_vp == vp)
2128 mtx_unlock(&sw_dev_mtx);
2133 error = swapoff_one(sp, td);
2135 swdev_syscall_active = 0;
2136 wakeup_one(&swdev_syscall_active);
2142 swapoff_one(struct swdevt *sp, struct thread *td)
2144 u_long nblks, dvbase;
2149 mtx_assert(&Giant, MA_OWNED);
2151 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY, td);
2152 error = mac_check_system_swapoff(td->td_ucred, sp->sw_vp);
2153 (void) VOP_UNLOCK(sp->sw_vp, 0, td);
2157 nblks = sp->sw_nblks;
2160 * We can turn off this swap device safely only if the
2161 * available virtual memory in the system will fit the amount
2162 * of data we will have to page back in, plus an epsilon so
2163 * the system doesn't become critically low on swap space.
2165 if (cnt.v_free_count + cnt.v_cache_count + swap_pager_avail <
2166 nblks + nswap_lowat) {
2171 * Prevent further allocations on this device.
2173 mtx_lock(&sw_dev_mtx);
2174 sp->sw_flags |= SW_CLOSING;
2175 for (dvbase = 0; dvbase < sp->sw_end; dvbase += dmmax) {
2176 swap_pager_avail -= blist_fill(sp->sw_blist,
2179 mtx_unlock(&sw_dev_mtx);
2182 * Page in the contents of the device and close it.
2184 swap_pager_swapoff(sp);
2186 sp->sw_close(td, sp);
2188 mtx_lock(&sw_dev_mtx);
2189 TAILQ_REMOVE(&swtailq, sp, sw_list);
2191 if (nswapdev == 0) {
2192 swap_pager_full = 2;
2193 swap_pager_almost_full = 1;
2197 mtx_unlock(&sw_dev_mtx);
2198 blist_destroy(sp->sw_blist);
2199 free(sp, M_VMPGDATA);
2206 struct swdevt *sp, *spt;
2207 const char *devname;
2211 while (swdev_syscall_active)
2212 tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0);
2213 swdev_syscall_active = 1;
2215 mtx_lock(&sw_dev_mtx);
2216 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) {
2217 mtx_unlock(&sw_dev_mtx);
2218 if (vn_isdisk(sp->sw_vp, NULL))
2219 devname = sp->sw_vp->v_rdev->si_name;
2222 error = swapoff_one(sp, &thread0);
2224 printf("Cannot remove swap device %s (error=%d), "
2225 "skipping.\n", devname, error);
2226 } else if (bootverbose) {
2227 printf("Swap device %s removed.\n", devname);
2229 mtx_lock(&sw_dev_mtx);
2231 mtx_unlock(&sw_dev_mtx);
2233 swdev_syscall_active = 0;
2234 wakeup_one(&swdev_syscall_active);
2239 swap_pager_status(int *total, int *used)
2245 mtx_lock(&sw_dev_mtx);
2246 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2247 *total += sp->sw_nblks;
2248 *used += sp->sw_used;
2250 mtx_unlock(&sw_dev_mtx);
2254 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS)
2256 int *name = (int *)arg1;
2261 if (arg2 != 1) /* name length */
2265 mtx_lock(&sw_dev_mtx);
2266 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2268 mtx_unlock(&sw_dev_mtx);
2269 xs.xsw_version = XSWDEV_VERSION;
2270 xs.xsw_dev = sp->sw_dev;
2271 xs.xsw_flags = sp->sw_flags;
2272 xs.xsw_nblks = sp->sw_nblks;
2273 xs.xsw_used = sp->sw_used;
2275 error = SYSCTL_OUT(req, &xs, sizeof(xs));
2280 mtx_unlock(&sw_dev_mtx);
2284 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0,
2285 "Number of swap devices");
2286 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD, sysctl_vm_swap_info,
2287 "Swap statistics by device");
2290 * vmspace_swap_count() - count the approximate swap useage in pages for a
2293 * The map must be locked.
2295 * Swap useage is determined by taking the proportional swap used by
2296 * VM objects backing the VM map. To make up for fractional losses,
2297 * if the VM object has any swap use at all the associated map entries
2298 * count for at least 1 swap page.
2301 vmspace_swap_count(struct vmspace *vmspace)
2303 vm_map_t map = &vmspace->vm_map;
2307 for (cur = map->header.next; cur != &map->header; cur = cur->next) {
2310 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 &&
2311 (object = cur->object.vm_object) != NULL) {
2312 VM_OBJECT_LOCK(object);
2313 if (object->type == OBJT_SWAP &&
2314 object->un_pager.swp.swp_bcount != 0) {
2315 int n = (cur->end - cur->start) / PAGE_SIZE;
2317 count += object->un_pager.swp.swp_bcount *
2318 SWAP_META_PAGES * n / object->size + 1;
2320 VM_OBJECT_UNLOCK(object);
2329 * Swapping onto disk devices.
2333 static g_orphan_t swapgeom_orphan;
2335 static struct g_class g_swap_class = {
2337 .version = G_VERSION,
2338 .orphan = swapgeom_orphan,
2341 DECLARE_GEOM_CLASS(g_swap_class, g_class);
2345 swapgeom_done(struct bio *bp2)
2349 bp = bp2->bio_caller2;
2350 bp->b_ioflags = bp2->bio_flags;
2352 bp->b_ioflags |= BIO_ERROR;
2353 bp->b_resid = bp->b_bcount - bp2->bio_completed;
2354 bp->b_error = bp2->bio_error;
2360 swapgeom_strategy(struct buf *bp, struct swdevt *sp)
2363 struct g_consumer *cp;
2367 bp->b_error = ENXIO;
2368 bp->b_ioflags |= BIO_ERROR;
2372 bio = g_alloc_bio();
2375 * XXX: We shouldn't really sleep here when we run out of buffers
2376 * XXX: but the alternative is worse right now.
2379 bp->b_error = ENOMEM;
2380 bp->b_ioflags |= BIO_ERROR;
2385 bio->bio_caller2 = bp;
2386 bio->bio_cmd = bp->b_iocmd;
2387 bio->bio_data = bp->b_data;
2388 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE;
2389 bio->bio_length = bp->b_bcount;
2390 bio->bio_done = swapgeom_done;
2391 g_io_request(bio, cp);
2396 swapgeom_orphan(struct g_consumer *cp)
2400 mtx_lock(&sw_dev_mtx);
2401 TAILQ_FOREACH(sp, &swtailq, sw_list)
2402 if (sp->sw_id == cp)
2404 mtx_unlock(&sw_dev_mtx);
2408 swapgeom_close_ev(void *arg, int flags)
2410 struct g_consumer *cp;
2413 g_access(cp, -1, -1, 0);
2415 g_destroy_consumer(cp);
2419 swapgeom_close(struct thread *td, struct swdevt *sw)
2422 /* XXX: direct call when Giant untangled */
2423 g_waitfor_event(swapgeom_close_ev, sw->sw_id, M_WAITOK, NULL);
2434 swapongeom_ev(void *arg, int flags)
2437 struct g_provider *pp;
2438 struct g_consumer *cp;
2439 static struct g_geom *gp;
2446 pp = g_dev_getprovider(swh->dev);
2448 swh->error = ENODEV;
2451 mtx_lock(&sw_dev_mtx);
2452 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2454 if (cp != NULL && cp->provider == pp) {
2455 mtx_unlock(&sw_dev_mtx);
2460 mtx_unlock(&sw_dev_mtx);
2462 gp = g_new_geomf(&g_swap_class, "swap", NULL);
2463 cp = g_new_consumer(gp);
2466 * XXX: Everytime you think you can improve the margin for
2467 * footshooting, somebody depends on the ability to do so:
2468 * savecore(8) wants to write to our swapdev so we cannot
2469 * set an exclusive count :-(
2471 error = g_access(cp, 1, 1, 0);
2474 g_destroy_consumer(cp);
2478 nblks = pp->mediasize / DEV_BSIZE;
2479 swaponsomething(swh->vp, cp, nblks, swapgeom_strategy,
2480 swapgeom_close, dev2udev(swh->dev));
2486 swapongeom(struct thread *td, struct vnode *vp)
2491 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
2493 swh.dev = vp->v_rdev;
2496 /* XXX: direct call when Giant untangled */
2497 error = g_waitfor_event(swapongeom_ev, &swh, M_WAITOK, NULL);
2500 VOP_UNLOCK(vp, 0, td);
2507 * This is used mainly for network filesystem (read: probably only tested
2508 * with NFS) swapfiles.
2513 swapdev_strategy(struct buf *bp, struct swdevt *sp)
2517 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first);
2521 if (bp->b_iocmd == BIO_WRITE) {
2523 bufobj_wdrop(bp->b_bufobj);
2524 bufobj_wref(&vp2->v_bufobj);
2526 if (bp->b_bufobj != &vp2->v_bufobj)
2527 bp->b_bufobj = &vp2->v_bufobj;
2529 bp->b_iooffset = dbtob(bp->b_blkno);
2535 swapdev_close(struct thread *td, struct swdevt *sp)
2538 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td);
2544 swaponvp(struct thread *td, struct vnode *vp, u_long nblks)
2551 mtx_lock(&sw_dev_mtx);
2552 TAILQ_FOREACH(sp, &swtailq, sw_list) {
2553 if (sp->sw_id == vp) {
2554 mtx_unlock(&sw_dev_mtx);
2558 mtx_unlock(&sw_dev_mtx);
2560 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
2562 error = mac_check_system_swapon(td->td_ucred, vp);
2565 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, -1);
2566 (void) VOP_UNLOCK(vp, 0, td);
2570 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close,