4 * Copyright (c) 1998-2010 The DragonFly Project. All rights reserved.
6 * This code is derived from software contributed to The DragonFly Project
7 * by Matthew Dillon <dillon@backplane.com>
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
19 * 3. Neither the name of The DragonFly Project nor the names of its
20 * contributors may be used to endorse or promote products derived
21 * from this software without specific, prior written permission.
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
26 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
27 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
28 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
29 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
30 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
31 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
32 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
33 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * Copyright (c) 1994 John S. Dyson
37 * Copyright (c) 1990 University of Utah.
38 * Copyright (c) 1991, 1993
39 * The Regents of the University of California. All rights reserved.
41 * This code is derived from software contributed to Berkeley by
42 * the Systems Programming Group of the University of Utah Computer
45 * Redistribution and use in source and binary forms, with or without
46 * modification, are permitted provided that the following conditions
48 * 1. Redistributions of source code must retain the above copyright
49 * notice, this list of conditions and the following disclaimer.
50 * 2. Redistributions in binary form must reproduce the above copyright
51 * notice, this list of conditions and the following disclaimer in the
52 * documentation and/or other materials provided with the distribution.
53 * 3. Neither the name of the University nor the names of its contributors
54 * may be used to endorse or promote products derived from this software
55 * without specific prior written permission.
57 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
58 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
59 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
60 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
61 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
62 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
63 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
64 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
65 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
66 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
72 * Radix Bitmap 'blists'.
74 * - The new swapper uses the new radix bitmap code. This should scale
75 * to arbitrarily small or arbitrarily large swap spaces and an almost
76 * arbitrary degree of fragmentation.
80 * - on the fly reallocation of swap during putpages. The new system
81 * does not try to keep previously allocated swap blocks for dirty
84 * - on the fly deallocation of swap
86 * - No more garbage collection required. Unnecessarily allocated swap
87 * blocks only exist for dirty vm_page_t's now and these are already
88 * cycled (in a high-load system) by the pager. We also do on-the-fly
89 * removal of invalidated swap blocks when a page is destroyed
92 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$
93 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94
94 * $FreeBSD: src/sys/vm/swap_pager.c,v 1.130.2.12 2002/08/31 21:15:55 dillon Exp $
98 #include <sys/param.h>
99 #include <sys/systm.h>
100 #include <sys/conf.h>
101 #include <sys/kernel.h>
102 #include <sys/proc.h>
104 #include <sys/vnode.h>
105 #include <sys/malloc.h>
106 #include <sys/vmmeter.h>
107 #include <sys/sysctl.h>
108 #include <sys/blist.h>
109 #include <sys/lock.h>
110 #include <sys/kcollect.h>
113 #include <vm/vm_object.h>
114 #include <vm/vm_page.h>
115 #include <vm/vm_pager.h>
116 #include <vm/vm_pageout.h>
117 #include <vm/swap_pager.h>
118 #include <vm/vm_extern.h>
119 #include <vm/vm_zone.h>
120 #include <vm/vnode_pager.h>
122 #include <sys/buf2.h>
123 #include <vm/vm_page2.h>
125 #ifndef MAX_PAGEOUT_CLUSTER
126 #define MAX_PAGEOUT_CLUSTER SWB_NPAGES
129 #define SWM_FREE 0x02 /* free, period */
130 #define SWM_POP 0x04 /* pop out */
132 #define SWBIO_READ 0x01
133 #define SWBIO_WRITE 0x02
134 #define SWBIO_SYNC 0x04
135 #define SWBIO_TTC 0x08 /* for OBJPC_TRY_TO_CACHE */
141 vm_pindex_t endi; /* inclusive */
144 struct swswapoffinfo {
151 * vm_swap_size is in page-sized chunks now. It was DEV_BSIZE'd chunks
155 int swap_pager_full; /* swap space exhaustion (task killing) */
156 int swap_fail_ticks; /* when we became exhausted */
157 int swap_pager_almost_full; /* swap space exhaustion (w/ hysteresis)*/
158 swblk_t vm_swap_cache_use;
159 swblk_t vm_swap_anon_use;
160 static int vm_report_swap_allocs;
162 static struct krate kswaprate = { 1 };
163 static int nsw_rcount; /* free read buffers */
164 static int nsw_wcount_sync; /* limit write buffers / synchronous */
165 static int nsw_wcount_async; /* limit write buffers / asynchronous */
166 static int nsw_wcount_async_max;/* assigned maximum */
167 static int nsw_cluster_max; /* maximum VOP I/O allowed */
169 struct blist *swapblist;
170 static int swap_async_max = 4; /* maximum in-progress async I/O's */
171 static int swap_burst_read = 0; /* allow burst reading */
172 static swblk_t swapiterator; /* linearize allocations */
173 int swap_user_async = 0; /* user swap pager operation can be async */
175 static struct spinlock swapbp_spin = SPINLOCK_INITIALIZER(&swapbp_spin, "swapbp_spin");
178 extern struct vnode *swapdev_vp;
179 extern struct swdevt *swdevt;
182 #define BLK2DEVIDX(blk) (nswdev > 1 ? blk / SWB_DMMAX % nswdev : 0)
184 SYSCTL_INT(_vm, OID_AUTO, swap_async_max,
185 CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops");
186 SYSCTL_INT(_vm, OID_AUTO, swap_burst_read,
187 CTLFLAG_RW, &swap_burst_read, 0, "Allow burst reads for pageins");
188 SYSCTL_INT(_vm, OID_AUTO, swap_user_async,
189 CTLFLAG_RW, &swap_user_async, 0, "Allow async uuser swap write I/O");
192 SYSCTL_LONG(_vm, OID_AUTO, swap_cache_use,
193 CTLFLAG_RD, &vm_swap_cache_use, 0, "");
194 SYSCTL_LONG(_vm, OID_AUTO, swap_anon_use,
195 CTLFLAG_RD, &vm_swap_anon_use, 0, "");
196 SYSCTL_LONG(_vm, OID_AUTO, swap_free,
197 CTLFLAG_RD, &vm_swap_size, 0, "");
198 SYSCTL_LONG(_vm, OID_AUTO, swap_size,
199 CTLFLAG_RD, &vm_swap_max, 0, "");
201 SYSCTL_INT(_vm, OID_AUTO, swap_cache_use,
202 CTLFLAG_RD, &vm_swap_cache_use, 0, "");
203 SYSCTL_INT(_vm, OID_AUTO, swap_anon_use,
204 CTLFLAG_RD, &vm_swap_anon_use, 0, "");
205 SYSCTL_INT(_vm, OID_AUTO, swap_free,
206 CTLFLAG_RD, &vm_swap_size, 0, "");
207 SYSCTL_INT(_vm, OID_AUTO, swap_size,
208 CTLFLAG_RD, &vm_swap_max, 0, "");
210 SYSCTL_INT(_vm, OID_AUTO, report_swap_allocs,
211 CTLFLAG_RW, &vm_report_swap_allocs, 0, "");
213 __read_mostly vm_zone_t swap_zone;
216 * Red-Black tree for swblock entries
218 * The caller must hold vm_token
220 RB_GENERATE2(swblock_rb_tree, swblock, swb_entry, rb_swblock_compare,
221 vm_pindex_t, swb_index);
224 rb_swblock_compare(struct swblock *swb1, struct swblock *swb2)
226 if (swb1->swb_index < swb2->swb_index)
228 if (swb1->swb_index > swb2->swb_index)
235 rb_swblock_scancmp(struct swblock *swb, void *data)
237 struct swfreeinfo *info = data;
239 if (swb->swb_index < info->basei)
241 if (swb->swb_index > info->endi)
248 rb_swblock_condcmp(struct swblock *swb, void *data)
250 struct swfreeinfo *info = data;
252 if (swb->swb_index < info->basei)
258 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure
259 * calls hooked from other parts of the VM system and do not appear here.
260 * (see vm/swap_pager.h).
263 static void swap_pager_dealloc (vm_object_t object);
264 static int swap_pager_getpage (vm_object_t, vm_pindex_t, vm_page_t *, int);
265 static void swap_chain_iodone(struct bio *biox);
267 struct pagerops swappagerops = {
268 swap_pager_dealloc, /* deallocate an OBJT_SWAP object */
269 swap_pager_getpage, /* pagein */
270 swap_pager_putpages, /* pageout */
271 swap_pager_haspage /* get backing store status for page */
275 * SWB_DMMAX is in page-sized chunks with the new swap system. It was
276 * dev-bsized chunks in the old. SWB_DMMAX is always a power of 2.
278 * swap_*() routines are externally accessible. swp_*() routines are
282 int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */
283 int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */
285 static __inline void swp_sizecheck (void);
286 static void swp_pager_async_iodone (struct bio *bio);
289 * Swap bitmap functions
292 static __inline void swp_pager_freeswapspace(vm_object_t object,
293 swblk_t blk, int npages);
294 static __inline swblk_t swp_pager_getswapspace(vm_object_t object, int npages);
300 static void swp_pager_meta_convert(vm_object_t);
301 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, swblk_t);
302 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t);
303 static void swp_pager_meta_free_all(vm_object_t);
304 static swblk_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int);
307 * SWP_SIZECHECK() - update swap_pager_full indication
309 * update the swap_pager_almost_full indication and warn when we are
310 * about to run out of swap space, using lowat/hiwat hysteresis.
312 * Clear swap_pager_full ( task killing ) indication when lowat is met.
314 * No restrictions on call
315 * This routine may not block.
321 if (vm_swap_size < nswap_lowat) {
322 if (swap_pager_almost_full == 0) {
323 kprintf("swap_pager: out of swap space\n");
324 swap_pager_almost_full = 1;
325 swap_fail_ticks = ticks;
329 if (vm_swap_size > nswap_hiwat)
330 swap_pager_almost_full = 0;
335 * Long-term data collection on 10-second interval. Return the value
336 * for KCOLLECT_SWAPPCT and set the values for SWAPANO and SWAPCCAC.
338 * Return total swap in the scale field. This can change if swap is
339 * regularly added or removed and may cause some historical confusion
340 * in that case, but SWAPPCT will always be historically accurate.
343 #define PTOB(value) ((uint64_t)(value) << PAGE_SHIFT)
346 collect_swap_callback(int n)
348 uint64_t total = vm_swap_max;
349 uint64_t anon = vm_swap_anon_use;
350 uint64_t cache = vm_swap_cache_use;
352 if (total == 0) /* avoid divide by zero */
354 kcollect_setvalue(KCOLLECT_SWAPANO, PTOB(anon));
355 kcollect_setvalue(KCOLLECT_SWAPCAC, PTOB(cache));
356 kcollect_setscale(KCOLLECT_SWAPANO,
357 KCOLLECT_SCALE(KCOLLECT_SWAPANO_FORMAT, PTOB(total)));
358 kcollect_setscale(KCOLLECT_SWAPCAC,
359 KCOLLECT_SCALE(KCOLLECT_SWAPCAC_FORMAT, PTOB(total)));
360 return (((anon + cache) * 10000 + (total >> 1)) / total);
364 * SWAP_PAGER_INIT() - initialize the swap pager!
366 * Expected to be started from system init. NOTE: This code is run
367 * before much else so be careful what you depend on. Most of the VM
368 * system has yet to be initialized at this point.
370 * Called from the low level boot code only.
373 swap_pager_init(void *arg __unused)
375 kcollect_register(KCOLLECT_SWAPPCT, "swapuse", collect_swap_callback,
376 KCOLLECT_SCALE(KCOLLECT_SWAPPCT_FORMAT, 0));
377 kcollect_register(KCOLLECT_SWAPANO, "swapano", NULL,
378 KCOLLECT_SCALE(KCOLLECT_SWAPANO_FORMAT, 0));
379 kcollect_register(KCOLLECT_SWAPCAC, "swapcac", NULL,
380 KCOLLECT_SCALE(KCOLLECT_SWAPCAC_FORMAT, 0));
382 SYSINIT(vm_mem, SI_BOOT1_VM, SI_ORDER_THIRD, swap_pager_init, NULL);
385 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process
387 * Expected to be started from pageout process once, prior to entering
390 * Called from the low level boot code only.
393 swap_pager_swap_init(void)
398 * Number of in-transit swap bp operations. Don't
399 * exhaust the pbufs completely. Make sure we
400 * initialize workable values (0 will work for hysteresis
401 * but it isn't very efficient).
403 * The nsw_cluster_max is constrained by the number of pages an XIO
404 * holds, i.e., (MAXPHYS/PAGE_SIZE) and our locally defined
405 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are
406 * constrained by the swap device interleave stripe size.
408 * Currently we hardwire nsw_wcount_async to 4. This limit is
409 * designed to prevent other I/O from having high latencies due to
410 * our pageout I/O. The value 4 works well for one or two active swap
411 * devices but is probably a little low if you have more. Even so,
412 * a higher value would probably generate only a limited improvement
413 * with three or four active swap devices since the system does not
414 * typically have to pageout at extreme bandwidths. We will want
415 * at least 2 per swap devices, and 4 is a pretty good value if you
416 * have one NFS swap device due to the command/ack latency over NFS.
417 * So it all works out pretty well.
420 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER);
422 nsw_rcount = (nswbuf_kva + 1) / 2;
423 nsw_wcount_sync = (nswbuf_kva + 3) / 4;
424 nsw_wcount_async = 4;
425 nsw_wcount_async_max = nsw_wcount_async;
428 * The zone is dynamically allocated so generally size it to
429 * maxswzone (32MB to 256GB of KVM). Set a minimum size based
430 * on physical memory of around 8x (each swblock can hold 16 pages).
432 * With the advent of SSDs (vs HDs) the practical (swap:memory) ratio
433 * has increased dramatically.
435 n = vmstats.v_page_count / 2;
436 if (maxswzone && n < maxswzone / sizeof(struct swblock))
437 n = maxswzone / sizeof(struct swblock);
443 sizeof(struct swblock),
446 if (swap_zone != NULL)
449 * if the allocation failed, try a zone two thirds the
450 * size of the previous attempt.
455 if (swap_zone == NULL)
456 panic("swap_pager_swap_init: swap_zone == NULL");
458 kprintf("Swap zone entries reduced from %d to %d.\n", n2, n);
462 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate
463 * its metadata structures.
465 * This routine is called from the mmap and fork code to create a new
466 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object
467 * and then converting it with swp_pager_meta_convert().
469 * We only support unnamed objects.
474 swap_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t offset)
478 KKASSERT(handle == NULL);
479 object = vm_object_allocate_hold(OBJT_DEFAULT,
480 OFF_TO_IDX(offset + PAGE_MASK + size));
481 swp_pager_meta_convert(object);
482 vm_object_drop(object);
488 * SWAP_PAGER_DEALLOC() - remove swap metadata from object
490 * The swap backing for the object is destroyed. The code is
491 * designed such that we can reinstantiate it later, but this
492 * routine is typically called only when the entire object is
493 * about to be destroyed.
495 * The object must be locked or unreferenceable.
496 * No other requirements.
499 swap_pager_dealloc(vm_object_t object)
501 vm_object_hold(object);
502 vm_object_pip_wait(object, "swpdea");
505 * Free all remaining metadata. We only bother to free it from
506 * the swap meta data. We do not attempt to free swapblk's still
507 * associated with vm_page_t's for this object. We do not care
508 * if paging is still in progress on some objects.
510 swp_pager_meta_free_all(object);
511 vm_object_drop(object);
514 /************************************************************************
515 * SWAP PAGER BITMAP ROUTINES *
516 ************************************************************************/
519 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space
521 * Allocate swap for the requested number of pages. The starting
522 * swap block number (a page index) is returned or SWAPBLK_NONE
523 * if the allocation failed.
525 * Also has the side effect of advising that somebody made a mistake
526 * when they configured swap and didn't configure enough.
528 * The caller must hold the object.
529 * This routine may not block.
531 static __inline swblk_t
532 swp_pager_getswapspace(vm_object_t object, int npages)
536 lwkt_gettoken(&vm_token);
537 blk = blist_allocat(swapblist, npages, swapiterator);
538 if (blk == SWAPBLK_NONE)
539 blk = blist_allocat(swapblist, npages, 0);
540 if (blk == SWAPBLK_NONE) {
541 if (swap_pager_full != 2) {
542 if (vm_swap_max == 0) {
543 krateprintf(&kswaprate,
544 "Warning: The system would like to "
545 "page to swap but no swap space "
548 krateprintf(&kswaprate,
549 "swap_pager_getswapspace: "
550 "swap full allocating %d pages\n",
554 if (swap_pager_almost_full == 0)
555 swap_fail_ticks = ticks;
556 swap_pager_almost_full = 1;
559 /* swapiterator = blk; disable for now, doesn't work well */
560 swapacctspace(blk, -npages);
561 if (object->type == OBJT_SWAP)
562 vm_swap_anon_use += npages;
564 vm_swap_cache_use += npages;
567 lwkt_reltoken(&vm_token);
572 * SWP_PAGER_FREESWAPSPACE() - free raw swap space
574 * This routine returns the specified swap blocks back to the bitmap.
576 * Note: This routine may not block (it could in the old swap code),
577 * and through the use of the new blist routines it does not block.
579 * This routine may not block.
583 swp_pager_freeswapspace(vm_object_t object, swblk_t blk, int npages)
585 struct swdevt *sp = &swdevt[BLK2DEVIDX(blk)];
587 lwkt_gettoken(&vm_token);
588 sp->sw_nused -= npages;
589 if (object->type == OBJT_SWAP)
590 vm_swap_anon_use -= npages;
592 vm_swap_cache_use -= npages;
594 if (sp->sw_flags & SW_CLOSING) {
595 lwkt_reltoken(&vm_token);
599 blist_free(swapblist, blk, npages);
600 vm_swap_size += npages;
602 lwkt_reltoken(&vm_token);
606 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page
607 * range within an object.
609 * This is a globally accessible routine.
611 * This routine removes swapblk assignments from swap metadata.
613 * The external callers of this routine typically have already destroyed
614 * or renamed vm_page_t's associated with this range in the object so
620 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_pindex_t size)
622 if (object->swblock_count == 0)
624 vm_object_hold(object);
625 swp_pager_meta_free(object, start, size);
626 vm_object_drop(object);
633 swap_pager_freespace_all(vm_object_t object)
635 if (object->swblock_count == 0)
637 vm_object_hold(object);
638 swp_pager_meta_free_all(object);
639 vm_object_drop(object);
643 * This function conditionally frees swap cache swap starting at
644 * (*basei) in the object. (count) swap blocks will be nominally freed.
645 * The actual number of blocks freed can be more or less than the
648 * This function nominally returns the number of blocks freed. However,
649 * the actual number of blocks freed may be less then the returned value.
650 * If the function is unable to exhaust the object or if it is able to
651 * free (approximately) the requested number of blocks it returns
654 * If we exhaust the object we will return a value n <= count.
656 * The caller must hold the object.
658 * WARNING! If count == 0 then -1 can be returned as a degenerate case,
659 * callers should always pass a count value > 0.
661 static int swap_pager_condfree_callback(struct swblock *swap, void *data);
664 swap_pager_condfree(vm_object_t object, vm_pindex_t *basei, int count)
666 struct swfreeinfo info;
670 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
672 info.object = object;
673 info.basei = *basei; /* skip up to this page index */
674 info.begi = count; /* max swap pages to destroy */
675 info.endi = count * 8; /* max swblocks to scan */
677 swblock_rb_tree_RB_SCAN(&object->swblock_root, rb_swblock_condcmp,
678 swap_pager_condfree_callback, &info);
682 * Take the higher difference swblocks vs pages
684 n = count - (int)info.begi;
685 t = count * 8 - (int)info.endi;
694 * The idea is to free whole meta-block to avoid fragmenting
695 * the swap space or disk I/O. We only do this if NO VM pages
698 * We do not have to deal with clearing PG_SWAPPED in related VM
699 * pages because there are no related VM pages.
701 * The caller must hold the object.
704 swap_pager_condfree_callback(struct swblock *swap, void *data)
706 struct swfreeinfo *info = data;
707 vm_object_t object = info->object;
710 for (i = 0; i < SWAP_META_PAGES; ++i) {
711 if (vm_page_lookup(object, swap->swb_index + i))
714 info->basei = swap->swb_index + SWAP_META_PAGES;
715 if (i == SWAP_META_PAGES) {
716 info->begi -= swap->swb_count;
717 swap_pager_freespace(object, swap->swb_index, SWAP_META_PAGES);
720 if ((int)info->begi < 0 || (int)info->endi < 0)
727 * Called by vm_page_alloc() when a new VM page is inserted
728 * into a VM object. Checks whether swap has been assigned to
729 * the page and sets PG_SWAPPED as necessary.
731 * (m) must be busied by caller and remains busied on return.
734 swap_pager_page_inserted(vm_page_t m)
736 if (m->object->swblock_count) {
737 vm_object_hold(m->object);
738 if (swp_pager_meta_ctl(m->object, m->pindex, 0) != SWAPBLK_NONE)
739 vm_page_flag_set(m, PG_SWAPPED);
740 vm_object_drop(m->object);
745 * SWAP_PAGER_RESERVE() - reserve swap blocks in object
747 * Assigns swap blocks to the specified range within the object. The
748 * swap blocks are not zerod. Any previous swap assignment is destroyed.
750 * Returns 0 on success, -1 on failure.
752 * The caller is responsible for avoiding races in the specified range.
753 * No other requirements.
756 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size)
759 swblk_t blk = SWAPBLK_NONE;
760 vm_pindex_t beg = start; /* save start index */
762 vm_object_hold(object);
767 while ((blk = swp_pager_getswapspace(object, n)) ==
772 swp_pager_meta_free(object, beg,
774 vm_object_drop(object);
779 swp_pager_meta_build(object, start, blk);
785 swp_pager_meta_free(object, start, n);
786 vm_object_drop(object);
791 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager
792 * and destroy the source.
794 * Copy any valid swapblks from the source to the destination. In
795 * cases where both the source and destination have a valid swapblk,
796 * we keep the destination's.
798 * This routine is allowed to block. It may block allocating metadata
799 * indirectly through swp_pager_meta_build() or if paging is still in
800 * progress on the source.
802 * XXX vm_page_collapse() kinda expects us not to block because we
803 * supposedly do not need to allocate memory, but for the moment we
804 * *may* have to get a little memory from the zone allocator, but
805 * it is taken from the interrupt memory. We should be ok.
807 * The source object contains no vm_page_t's (which is just as well)
808 * The source object is of type OBJT_SWAP.
810 * The source and destination objects must be held by the caller.
813 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
814 vm_pindex_t base_index, int destroysource)
818 ASSERT_LWKT_TOKEN_HELD(vm_object_token(srcobject));
819 ASSERT_LWKT_TOKEN_HELD(vm_object_token(dstobject));
822 * transfer source to destination.
824 for (i = 0; i < dstobject->size; ++i) {
828 * Locate (without changing) the swapblk on the destination,
829 * unless it is invalid in which case free it silently, or
830 * if the destination is a resident page, in which case the
831 * source is thrown away.
833 dstaddr = swp_pager_meta_ctl(dstobject, i, 0);
835 if (dstaddr == SWAPBLK_NONE) {
837 * Destination has no swapblk and is not resident,
842 srcaddr = swp_pager_meta_ctl(srcobject,
843 base_index + i, SWM_POP);
845 if (srcaddr != SWAPBLK_NONE)
846 swp_pager_meta_build(dstobject, i, srcaddr);
849 * Destination has valid swapblk or it is represented
850 * by a resident page. We destroy the sourceblock.
852 swp_pager_meta_ctl(srcobject, base_index + i, SWM_FREE);
857 * Free left over swap blocks in source.
859 * We have to revert the type to OBJT_DEFAULT so we do not accidently
860 * double-remove the object from the swap queues.
864 * Reverting the type is not necessary, the caller is going
865 * to destroy srcobject directly, but I'm doing it here
866 * for consistency since we've removed the object from its
869 swp_pager_meta_free_all(srcobject);
870 if (srcobject->type == OBJT_SWAP)
871 srcobject->type = OBJT_DEFAULT;
876 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for
877 * the requested page.
879 * We determine whether good backing store exists for the requested
880 * page and return TRUE if it does, FALSE if it doesn't.
882 * If TRUE, we also try to determine how much valid, contiguous backing
883 * store exists before and after the requested page within a reasonable
884 * distance. We do not try to restrict it to the swap device stripe
885 * (that is handled in getpages/putpages). It probably isn't worth
891 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex)
896 * do we have good backing store at the requested index ?
898 vm_object_hold(object);
899 blk0 = swp_pager_meta_ctl(object, pindex, 0);
901 if (blk0 == SWAPBLK_NONE) {
902 vm_object_drop(object);
905 vm_object_drop(object);
910 * Object must be held exclusive or shared by the caller.
913 swap_pager_haspage_locked(vm_object_t object, vm_pindex_t pindex)
915 if (swp_pager_meta_ctl(object, pindex, 0) == SWAPBLK_NONE)
921 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page
923 * This removes any associated swap backing store, whether valid or
924 * not, from the page. This operates on any VM object, not just OBJT_SWAP
927 * This routine is typically called when a page is made dirty, at
928 * which point any associated swap can be freed. MADV_FREE also
929 * calls us in a special-case situation
931 * NOTE!!! If the page is clean and the swap was valid, the caller
932 * should make the page dirty before calling this routine.
933 * This routine does NOT change the m->dirty status of the page.
934 * Also: MADV_FREE depends on it.
936 * The page must be busied.
937 * The caller can hold the object to avoid blocking, else we might block.
938 * No other requirements.
941 swap_pager_unswapped(vm_page_t m)
943 if (m->flags & PG_SWAPPED) {
944 vm_object_hold(m->object);
945 KKASSERT(m->flags & PG_SWAPPED);
946 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE);
947 vm_page_flag_clear(m, PG_SWAPPED);
948 vm_object_drop(m->object);
953 * SWAP_PAGER_STRATEGY() - read, write, free blocks
955 * This implements a VM OBJECT strategy function using swap backing store.
956 * This can operate on any VM OBJECT type, not necessarily just OBJT_SWAP
957 * types. Only BUF_CMD_{READ,WRITE,FREEBLKS} is supported, any other
958 * requests will return EINVAL.
960 * This is intended to be a cacheless interface (i.e. caching occurs at
961 * higher levels), and is also used as a swap-based SSD cache for vnode
962 * and device objects.
964 * All I/O goes directly to and from the swap device.
966 * We currently attempt to run I/O synchronously or asynchronously as
967 * the caller requests. This isn't perfect because we loose error
968 * sequencing when we run multiple ops in parallel to satisfy a request.
969 * But this is swap, so we let it all hang out.
971 * NOTE: This function supports the KVABIO API wherein bp->b_data might
972 * not be synchronized to the current cpu.
977 swap_pager_strategy(vm_object_t object, struct bio *bio)
979 struct buf *bp = bio->bio_buf;
982 vm_pindex_t biox_blkno = 0;
988 struct bio_track *track;
993 * tracking for swapdev vnode I/Os
995 if (bp->b_cmd == BUF_CMD_READ)
996 track = &swapdev_vp->v_track_read;
998 track = &swapdev_vp->v_track_write;
1002 * Only supported commands
1004 if (bp->b_cmd != BUF_CMD_FREEBLKS &&
1005 bp->b_cmd != BUF_CMD_READ &&
1006 bp->b_cmd != BUF_CMD_WRITE) {
1007 bp->b_error = EINVAL;
1008 bp->b_flags |= B_ERROR | B_INVAL;
1014 * bcount must be an integral number of pages.
1016 if (bp->b_bcount & PAGE_MASK) {
1017 bp->b_error = EINVAL;
1018 bp->b_flags |= B_ERROR | B_INVAL;
1020 kprintf("swap_pager_strategy: bp %p offset %lld size %d, "
1021 "not page bounded\n",
1022 bp, (long long)bio->bio_offset, (int)bp->b_bcount);
1027 * Clear error indication, initialize page index, count, data pointer.
1030 bp->b_flags &= ~B_ERROR;
1031 bp->b_resid = bp->b_bcount;
1033 start = (vm_pindex_t)(bio->bio_offset >> PAGE_SHIFT);
1034 count = howmany(bp->b_bcount, PAGE_SIZE);
1037 * WARNING! Do not dereference *data without issuing a bkvasync()
1042 * Deal with BUF_CMD_FREEBLKS
1044 if (bp->b_cmd == BUF_CMD_FREEBLKS) {
1046 * FREE PAGE(s) - destroy underlying swap that is no longer
1049 vm_object_hold(object);
1050 swp_pager_meta_free(object, start, count);
1051 vm_object_drop(object);
1058 * We need to be able to create a new cluster of I/O's. We cannot
1059 * use the caller fields of the passed bio so push a new one.
1061 * Because nbio is just a placeholder for the cluster links,
1062 * we can biodone() the original bio instead of nbio to make
1063 * things a bit more efficient.
1065 nbio = push_bio(bio);
1066 nbio->bio_offset = bio->bio_offset;
1067 nbio->bio_caller_info1.cluster_head = NULL;
1068 nbio->bio_caller_info2.cluster_tail = NULL;
1074 * Execute read or write
1076 vm_object_hold(object);
1082 * Obtain block. If block not found and writing, allocate a
1083 * new block and build it into the object.
1085 blk = swp_pager_meta_ctl(object, start, 0);
1086 if ((blk == SWAPBLK_NONE) && bp->b_cmd == BUF_CMD_WRITE) {
1087 blk = swp_pager_getswapspace(object, 1);
1088 if (blk == SWAPBLK_NONE) {
1089 bp->b_error = ENOMEM;
1090 bp->b_flags |= B_ERROR;
1093 swp_pager_meta_build(object, start, blk);
1097 * Do we have to flush our current collection? Yes if:
1099 * - no swap block at this index
1100 * - swap block is not contiguous
1101 * - we cross a physical disk boundry in the
1105 (biox_blkno + btoc(bufx->b_bcount) != blk ||
1106 ((biox_blkno ^ blk) & ~SWB_DMMASK))) {
1109 ++mycpu->gd_cnt.v_swapin;
1110 mycpu->gd_cnt.v_swappgsin +=
1111 btoc(bufx->b_bcount);
1114 ++mycpu->gd_cnt.v_swapout;
1115 mycpu->gd_cnt.v_swappgsout +=
1116 btoc(bufx->b_bcount);
1117 bufx->b_dirtyend = bufx->b_bcount;
1125 * Finished with this buf.
1127 KKASSERT(bufx->b_bcount != 0);
1128 if (bufx->b_cmd != BUF_CMD_READ)
1129 bufx->b_dirtyend = bufx->b_bcount;
1135 * Add new swapblk to biox, instantiating biox if necessary.
1136 * Zero-fill reads are able to take a shortcut.
1138 if (blk == SWAPBLK_NONE) {
1140 * We can only get here if we are reading.
1143 bzero(data, PAGE_SIZE);
1144 bp->b_resid -= PAGE_SIZE;
1147 /* XXX chain count > 4, wait to <= 4 */
1149 bufx = getpbuf(NULL);
1150 bufx->b_flags |= B_KVABIO;
1151 biox = &bufx->b_bio1;
1152 cluster_append(nbio, bufx);
1153 bufx->b_cmd = bp->b_cmd;
1154 biox->bio_done = swap_chain_iodone;
1155 biox->bio_offset = (off_t)blk << PAGE_SHIFT;
1156 biox->bio_caller_info1.cluster_parent = nbio;
1159 bufx->b_data = data;
1161 bufx->b_bcount += PAGE_SIZE;
1168 vm_object_drop(object);
1171 * Flush out last buffer
1174 if (bufx->b_cmd == BUF_CMD_READ) {
1175 ++mycpu->gd_cnt.v_swapin;
1176 mycpu->gd_cnt.v_swappgsin += btoc(bufx->b_bcount);
1178 ++mycpu->gd_cnt.v_swapout;
1179 mycpu->gd_cnt.v_swappgsout += btoc(bufx->b_bcount);
1180 bufx->b_dirtyend = bufx->b_bcount;
1182 KKASSERT(bufx->b_bcount);
1183 if (bufx->b_cmd != BUF_CMD_READ)
1184 bufx->b_dirtyend = bufx->b_bcount;
1185 /* biox, bufx = NULL */
1189 * Now initiate all the I/O. Be careful looping on our chain as
1190 * I/O's may complete while we are still initiating them.
1192 * If the request is a 100% sparse read no bios will be present
1193 * and we just biodone() the buffer.
1195 nbio->bio_caller_info2.cluster_tail = NULL;
1196 bufx = nbio->bio_caller_info1.cluster_head;
1200 biox = &bufx->b_bio1;
1202 bufx = bufx->b_cluster_next;
1203 vn_strategy(swapdev_vp, biox);
1210 * Completion of the cluster will also call biodone_chain(nbio).
1211 * We never call biodone(nbio) so we don't have to worry about
1212 * setting up a bio_done callback. It's handled in the sub-IO.
1223 swap_chain_iodone(struct bio *biox)
1226 struct buf *bufx; /* chained sub-buffer */
1227 struct bio *nbio; /* parent nbio with chain glue */
1228 struct buf *bp; /* original bp associated with nbio */
1231 bufx = biox->bio_buf;
1232 nbio = biox->bio_caller_info1.cluster_parent;
1236 * Update the original buffer
1238 KKASSERT(bp != NULL);
1239 if (bufx->b_flags & B_ERROR) {
1240 atomic_set_int(&bufx->b_flags, B_ERROR);
1241 bp->b_error = bufx->b_error; /* race ok */
1242 } else if (bufx->b_resid != 0) {
1243 atomic_set_int(&bufx->b_flags, B_ERROR);
1244 bp->b_error = EINVAL; /* race ok */
1246 atomic_subtract_int(&bp->b_resid, bufx->b_bcount);
1250 * Remove us from the chain.
1252 spin_lock(&swapbp_spin);
1253 nextp = &nbio->bio_caller_info1.cluster_head;
1254 while (*nextp != bufx) {
1255 KKASSERT(*nextp != NULL);
1256 nextp = &(*nextp)->b_cluster_next;
1258 *nextp = bufx->b_cluster_next;
1259 chain_empty = (nbio->bio_caller_info1.cluster_head == NULL);
1260 spin_unlock(&swapbp_spin);
1263 * Clean up bufx. If the chain is now empty we finish out
1264 * the parent. Note that we may be racing other completions
1265 * so we must use the chain_empty status from above.
1268 if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) {
1269 atomic_set_int(&bp->b_flags, B_ERROR);
1270 bp->b_error = EINVAL;
1272 biodone_chain(nbio);
1274 relpbuf(bufx, NULL);
1278 * SWAP_PAGER_GETPAGES() - bring page in from swap
1280 * The requested page may have to be brought in from swap. Calculate the
1281 * swap block and bring in additional pages if possible. All pages must
1282 * have contiguous swap block assignments and reside in the same object.
1284 * The caller has a single vm_object_pip_add() reference prior to
1285 * calling us and we should return with the same.
1287 * The caller has BUSY'd the page. We should return with (*mpp) left busy,
1288 * and any additinal pages unbusied.
1290 * If the caller encounters a PG_RAM page it will pass it to us even though
1291 * it may be valid and dirty. We cannot overwrite the page in this case!
1292 * The case is used to allow us to issue pure read-aheads.
1294 * NOTE! XXX This code does not entirely pipeline yet due to the fact that
1295 * the PG_RAM page is validated at the same time as mreq. What we
1296 * really need to do is issue a separate read-ahead pbuf.
1301 swap_pager_getpage(vm_object_t object, vm_pindex_t pindex,
1302 vm_page_t *mpp, int seqaccess)
1314 u_int32_t busy_count;
1315 vm_page_t marray[XIO_INTERNAL_PAGES];
1319 vm_object_hold(object);
1320 if (mreq->object != object) {
1321 panic("swap_pager_getpages: object mismatch %p/%p",
1328 * We don't want to overwrite a fully valid page as it might be
1329 * dirty. This case can occur when e.g. vm_fault hits a perfectly
1330 * valid page with PG_RAM set.
1332 * In this case we see if the next page is a suitable page-in
1333 * candidate and if it is we issue read-ahead. PG_RAM will be
1334 * set on the last page of the read-ahead to continue the pipeline.
1336 if (mreq->valid == VM_PAGE_BITS_ALL) {
1337 if (swap_burst_read == 0 || mreq->pindex + 1 >= object->size) {
1338 vm_object_drop(object);
1339 return(VM_PAGER_OK);
1341 blk = swp_pager_meta_ctl(object, mreq->pindex + 1, 0);
1342 if (blk == SWAPBLK_NONE) {
1343 vm_object_drop(object);
1344 return(VM_PAGER_OK);
1346 m = vm_page_lookup_busy_try(object, mreq->pindex + 1,
1349 vm_object_drop(object);
1350 return(VM_PAGER_OK);
1351 } else if (m == NULL) {
1353 * Use VM_ALLOC_QUICK to avoid blocking on cache
1356 m = vm_page_alloc(object, mreq->pindex + 1,
1359 vm_object_drop(object);
1360 return(VM_PAGER_OK);
1365 vm_object_drop(object);
1366 return(VM_PAGER_OK);
1368 vm_page_unqueue_nowakeup(m);
1378 * Try to block-read contiguous pages from swap if sequential,
1379 * otherwise just read one page. Contiguous pages from swap must
1380 * reside within a single device stripe because the I/O cannot be
1381 * broken up across multiple stripes.
1383 * Note that blk and iblk can be SWAPBLK_NONE but the loop is
1384 * set up such that the case(s) are handled implicitly.
1386 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0);
1389 for (i = 1; i <= swap_burst_read &&
1390 i < XIO_INTERNAL_PAGES &&
1391 mreq->pindex + i < object->size; ++i) {
1394 iblk = swp_pager_meta_ctl(object, mreq->pindex + i, 0);
1395 if (iblk != blk + i)
1397 if ((blk ^ iblk) & ~SWB_DMMASK)
1399 m = vm_page_lookup_busy_try(object, mreq->pindex + i,
1403 } else if (m == NULL) {
1405 * Use VM_ALLOC_QUICK to avoid blocking on cache
1408 m = vm_page_alloc(object, mreq->pindex + i,
1417 vm_page_unqueue_nowakeup(m);
1423 vm_page_flag_set(marray[i - 1], PG_RAM);
1426 * If mreq is the requested page and we have nothing to do return
1427 * VM_PAGER_FAIL. If raonly is set mreq is just another read-ahead
1428 * page and must be cleaned up.
1430 if (blk == SWAPBLK_NONE) {
1433 vnode_pager_freepage(mreq);
1434 vm_object_drop(object);
1435 return(VM_PAGER_OK);
1437 vm_object_drop(object);
1438 return(VM_PAGER_FAIL);
1443 * Map our page(s) into kva for input
1445 * Use the KVABIO API to avoid synchronizing the pmap.
1447 bp = getpbuf_kva(&nsw_rcount);
1449 kva = (vm_offset_t) bp->b_kvabase;
1450 bcopy(marray, bp->b_xio.xio_pages, i * sizeof(vm_page_t));
1451 pmap_qenter_noinval(kva, bp->b_xio.xio_pages, i);
1453 bp->b_data = (caddr_t)kva;
1454 bp->b_bcount = PAGE_SIZE * i;
1455 bp->b_xio.xio_npages = i;
1456 bp->b_flags |= B_KVABIO;
1457 bio->bio_done = swp_pager_async_iodone;
1458 bio->bio_offset = (off_t)blk << PAGE_SHIFT;
1459 bio->bio_caller_info1.index = SWBIO_READ;
1462 * Set index. If raonly set the index beyond the array so all
1463 * the pages are treated the same, otherwise the original mreq is
1467 bio->bio_driver_info = (void *)(intptr_t)i;
1469 bio->bio_driver_info = (void *)(intptr_t)0;
1471 for (j = 0; j < i; ++j) {
1472 atomic_set_int(&bp->b_xio.xio_pages[j]->busy_count,
1476 mycpu->gd_cnt.v_swapin++;
1477 mycpu->gd_cnt.v_swappgsin += bp->b_xio.xio_npages;
1480 * We still hold the lock on mreq, and our automatic completion routine
1481 * does not remove it.
1483 vm_object_pip_add(object, bp->b_xio.xio_npages);
1486 * perform the I/O. NOTE!!! bp cannot be considered valid after
1487 * this point because we automatically release it on completion.
1488 * Instead, we look at the one page we are interested in which we
1489 * still hold a lock on even through the I/O completion.
1491 * The other pages in our m[] array are also released on completion,
1492 * so we cannot assume they are valid anymore either.
1494 bp->b_cmd = BUF_CMD_READ;
1496 vn_strategy(swapdev_vp, bio);
1499 * Wait for the page we want to complete. PBUSY_SWAPINPROG is always
1500 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE
1501 * is set in the meta-data.
1503 * If this is a read-ahead only we return immediately without
1507 vm_object_drop(object);
1508 return(VM_PAGER_OK);
1512 * Read-ahead includes originally requested page case.
1515 busy_count = mreq->busy_count;
1517 if ((busy_count & PBUSY_SWAPINPROG) == 0)
1519 tsleep_interlock(mreq, 0);
1520 if (!atomic_cmpset_int(&mreq->busy_count, busy_count,
1522 PBUSY_SWAPINPROG | PBUSY_WANTED)) {
1525 atomic_set_int(&mreq->flags, PG_REFERENCED);
1526 mycpu->gd_cnt.v_intrans++;
1527 if (tsleep(mreq, PINTERLOCKED, "swread", hz*20)) {
1529 "swap_pager: indefinite wait buffer: "
1530 " bp %p offset: %lld, size: %ld "
1531 " m=%p busy=%08x flags=%08x\n",
1533 (long long)bio->bio_offset,
1535 mreq, mreq->busy_count, mreq->flags);
1540 * Disallow speculative reads prior to the SWAPINPROG test.
1545 * mreq is left busied after completion, but all the other pages
1546 * are freed. If we had an unrecoverable read error the page will
1549 vm_object_drop(object);
1550 if (mreq->valid != VM_PAGE_BITS_ALL)
1551 return(VM_PAGER_ERROR);
1553 return(VM_PAGER_OK);
1556 * A final note: in a low swap situation, we cannot deallocate swap
1557 * and mark a page dirty here because the caller is likely to mark
1558 * the page clean when we return, causing the page to possibly revert
1559 * to all-zero's later.
1564 * swap_pager_putpages:
1566 * Assign swap (if necessary) and initiate I/O on the specified pages.
1568 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects
1569 * are automatically converted to SWAP objects.
1571 * In a low memory situation we may block in vn_strategy(), but the new
1572 * vm_page reservation system coupled with properly written VFS devices
1573 * should ensure that no low-memory deadlock occurs. This is an area
1576 * The parent has N vm_object_pip_add() references prior to
1577 * calling us and will remove references for rtvals[] that are
1578 * not set to VM_PAGER_PEND. We need to remove the rest on I/O
1581 * The parent has soft-busy'd the pages it passes us and will unbusy
1582 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return.
1583 * We need to unbusy the rest on I/O completion.
1588 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count,
1589 int flags, int *rtvals)
1594 vm_object_hold(object);
1596 if (count && m[0]->object != object) {
1597 panic("swap_pager_getpages: object mismatch %p/%p",
1606 * Turn object into OBJT_SWAP
1607 * Check for bogus sysops
1609 * Force sync if not pageout process, we don't want any single
1610 * non-pageout process to be able to hog the I/O subsystem! This
1611 * can be overridden by setting.
1613 if (object->type == OBJT_DEFAULT) {
1614 if (object->type == OBJT_DEFAULT)
1615 swp_pager_meta_convert(object);
1619 * Normally we force synchronous swap I/O if this is not the
1620 * pageout daemon to prevent any single user process limited
1621 * via RLIMIT_RSS from hogging swap write bandwidth.
1623 if (curthread != pagethread &&
1624 curthread != emergpager &&
1625 swap_user_async == 0) {
1626 flags |= OBJPC_SYNC;
1632 * Update nsw parameters from swap_async_max sysctl values.
1633 * Do not let the sysop crash the machine with bogus numbers.
1635 if (swap_async_max != nsw_wcount_async_max) {
1641 if ((n = swap_async_max) > nswbuf_kva / 2)
1648 * Adjust difference ( if possible ). If the current async
1649 * count is too low, we may not be able to make the adjustment
1652 * vm_token needed for nsw_wcount sleep interlock
1654 lwkt_gettoken(&vm_token);
1655 n -= nsw_wcount_async_max;
1656 if (nsw_wcount_async + n >= 0) {
1657 nsw_wcount_async_max += n;
1658 pbuf_adjcount(&nsw_wcount_async, n);
1660 lwkt_reltoken(&vm_token);
1666 * Assign swap blocks and issue I/O. We reallocate swap on the fly.
1667 * The page is left dirty until the pageout operation completes
1671 for (i = 0; i < count; i += n) {
1678 * Maximum I/O size is limited by a number of factors.
1681 n = min(BLIST_MAX_ALLOC, count - i);
1682 n = min(n, nsw_cluster_max);
1684 lwkt_gettoken(&vm_token);
1687 * Get biggest block of swap we can. If we fail, fall
1688 * back and try to allocate a smaller block. Don't go
1689 * overboard trying to allocate space if it would overly
1693 (blk = swp_pager_getswapspace(object, n)) == SWAPBLK_NONE &&
1698 if (blk == SWAPBLK_NONE) {
1699 for (j = 0; j < n; ++j)
1700 rtvals[i+j] = VM_PAGER_FAIL;
1701 lwkt_reltoken(&vm_token);
1704 if (vm_report_swap_allocs > 0) {
1705 kprintf("swap_alloc %08jx,%d\n", (intmax_t)blk, n);
1706 --vm_report_swap_allocs;
1710 * The I/O we are constructing cannot cross a physical
1711 * disk boundry in the swap stripe.
1713 if ((blk ^ (blk + n)) & ~SWB_DMMASK) {
1714 j = ((blk + SWB_DMMAX) & ~SWB_DMMASK) - blk;
1715 swp_pager_freeswapspace(object, blk + j, n - j);
1720 * All I/O parameters have been satisfied, build the I/O
1721 * request and assign the swap space.
1723 * Use the KVABIO API to avoid synchronizing the pmap.
1725 if ((flags & OBJPC_SYNC))
1726 bp = getpbuf_kva(&nsw_wcount_sync);
1728 bp = getpbuf_kva(&nsw_wcount_async);
1731 lwkt_reltoken(&vm_token);
1733 pmap_qenter_noinval((vm_offset_t)bp->b_data, &m[i], n);
1735 bp->b_flags |= B_KVABIO;
1736 bp->b_bcount = PAGE_SIZE * n;
1737 bio->bio_offset = (off_t)blk << PAGE_SHIFT;
1739 for (j = 0; j < n; ++j) {
1740 vm_page_t mreq = m[i+j];
1742 swp_pager_meta_build(mreq->object, mreq->pindex,
1744 if (object->type == OBJT_SWAP)
1745 vm_page_dirty(mreq);
1746 rtvals[i+j] = VM_PAGER_OK;
1748 atomic_set_int(&mreq->busy_count, PBUSY_SWAPINPROG);
1749 bp->b_xio.xio_pages[j] = mreq;
1751 bp->b_xio.xio_npages = n;
1753 mycpu->gd_cnt.v_swapout++;
1754 mycpu->gd_cnt.v_swappgsout += bp->b_xio.xio_npages;
1756 bp->b_dirtyoff = 0; /* req'd for NFS */
1757 bp->b_dirtyend = bp->b_bcount; /* req'd for NFS */
1758 bp->b_cmd = BUF_CMD_WRITE;
1759 bio->bio_caller_info1.index = SWBIO_WRITE;
1764 if ((flags & OBJPC_SYNC) == 0) {
1765 bio->bio_done = swp_pager_async_iodone;
1767 vn_strategy(swapdev_vp, bio);
1769 for (j = 0; j < n; ++j)
1770 rtvals[i+j] = VM_PAGER_PEND;
1775 * Issue synchrnously.
1777 * Wait for the sync I/O to complete, then update rtvals.
1778 * We just set the rtvals[] to VM_PAGER_PEND so we can call
1779 * our async completion routine at the end, thus avoiding a
1782 bio->bio_caller_info1.index |= SWBIO_SYNC;
1783 if (flags & OBJPC_TRY_TO_CACHE)
1784 bio->bio_caller_info1.index |= SWBIO_TTC;
1785 bio->bio_done = biodone_sync;
1786 bio->bio_flags |= BIO_SYNC;
1787 vn_strategy(swapdev_vp, bio);
1788 biowait(bio, "swwrt");
1790 for (j = 0; j < n; ++j)
1791 rtvals[i+j] = VM_PAGER_PEND;
1794 * Now that we are through with the bp, we can call the
1795 * normal async completion, which frees everything up.
1797 swp_pager_async_iodone(bio);
1799 vm_object_drop(object);
1805 * Recalculate the low and high-water marks.
1808 swap_pager_newswap(void)
1811 * NOTE: vm_swap_max cannot exceed 1 billion blocks, which is the
1812 * limitation imposed by the blist code. Remember that this
1813 * will be divided by NSWAP_MAX (4), so each swap device is
1814 * limited to around a terrabyte.
1817 nswap_lowat = (int64_t)vm_swap_max * 4 / 100; /* 4% left */
1818 nswap_hiwat = (int64_t)vm_swap_max * 6 / 100; /* 6% left */
1819 kprintf("swap low/high-water marks set to %d/%d\n",
1820 nswap_lowat, nswap_hiwat);
1829 * swp_pager_async_iodone:
1831 * Completion routine for asynchronous reads and writes from/to swap.
1832 * Also called manually by synchronous code to finish up a bp.
1834 * For READ operations, the pages are BUSY'd. For WRITE operations,
1835 * the pages are vm_page_t->busy'd. For READ operations, we BUSY
1836 * unbusy all pages except the 'main' request page. For WRITE
1837 * operations, we vm_page_t->busy'd unbusy all pages ( we can do this
1838 * because we marked them all VM_PAGER_PEND on return from putpages ).
1840 * This routine may not block.
1845 swp_pager_async_iodone(struct bio *bio)
1847 struct buf *bp = bio->bio_buf;
1848 vm_object_t object = NULL;
1855 if (bp->b_flags & B_ERROR) {
1857 "swap_pager: I/O error - %s failed; offset %lld,"
1858 "size %ld, error %d\n",
1859 ((bio->bio_caller_info1.index & SWBIO_READ) ?
1860 "pagein" : "pageout"),
1861 (long long)bio->bio_offset,
1870 if (bp->b_xio.xio_npages)
1871 object = bp->b_xio.xio_pages[0]->object;
1874 /* PMAP TESTING CODE (useful, keep it in but #if 0'd) */
1875 if (bio->bio_caller_info1.index & SWBIO_WRITE) {
1876 if (bio->bio_crc != iscsi_crc32(bp->b_data, bp->b_bcount)) {
1877 kprintf("SWAPOUT: BADCRC %08x %08x\n",
1879 iscsi_crc32(bp->b_data, bp->b_bcount));
1880 for (i = 0; i < bp->b_xio.xio_npages; ++i) {
1881 vm_page_t m = bp->b_xio.xio_pages[i];
1882 if ((m->flags & PG_WRITEABLE) &&
1883 (pmap_mapped_sync(m) & PG_WRITEABLE)) {
1885 "%d/%d %p writable\n",
1886 i, bp->b_xio.xio_npages, m);
1894 * remove the mapping for kernel virtual
1896 pmap_qremove((vm_offset_t)bp->b_data, bp->b_xio.xio_npages);
1899 * cleanup pages. If an error occurs writing to swap, we are in
1900 * very serious trouble. If it happens to be a disk error, though,
1901 * we may be able to recover by reassigning the swap later on. So
1902 * in this case we remove the m->swapblk assignment for the page
1903 * but do not free it in the rlist. The errornous block(s) are thus
1904 * never reallocated as swap. Redirty the page and continue.
1906 for (i = 0; i < bp->b_xio.xio_npages; ++i) {
1907 vm_page_t m = bp->b_xio.xio_pages[i];
1909 if (bp->b_flags & B_ERROR) {
1911 * If an error occurs I'd love to throw the swapblk
1912 * away without freeing it back to swapspace, so it
1913 * can never be used again. But I can't from an
1917 if (bio->bio_caller_info1.index & SWBIO_READ) {
1919 * When reading, reqpage needs to stay
1920 * locked for the parent, but all other
1921 * pages can be freed. We still want to
1922 * wakeup the parent waiting on the page,
1923 * though. ( also: pg_reqpage can be -1 and
1924 * not match anything ).
1926 * We have to wake specifically requested pages
1927 * up too because we cleared SWAPINPROG and
1928 * someone may be waiting for that.
1930 * NOTE: For reads, m->dirty will probably
1931 * be overridden by the original caller
1932 * of getpages so don't play cute tricks
1935 * NOTE: We can't actually free the page from
1936 * here, because this is an interrupt.
1937 * It is not legal to mess with
1938 * object->memq from an interrupt.
1939 * Deactivate the page instead.
1941 * WARNING! The instant SWAPINPROG is
1942 * cleared another cpu may start
1943 * using the mreq page (it will
1944 * check m->valid immediately).
1948 atomic_clear_int(&m->busy_count,
1952 * bio_driver_info holds the requested page
1955 if (i != (int)(intptr_t)bio->bio_driver_info) {
1956 vm_page_deactivate(m);
1962 * If i == bp->b_pager.pg_reqpage, do not wake
1963 * the page up. The caller needs to.
1967 * If a write error occurs remove the swap
1968 * assignment (note that PG_SWAPPED may or
1969 * may not be set depending on prior activity).
1971 * Re-dirty OBJT_SWAP pages as there is no
1972 * other backing store, we can't throw the
1975 * Non-OBJT_SWAP pages (aka swapcache) must
1976 * not be dirtied since they may not have
1977 * been dirty in the first place, and they
1978 * do have backing store (the vnode).
1980 vm_page_busy_wait(m, FALSE, "swadpg");
1981 vm_object_hold(m->object);
1982 swp_pager_meta_ctl(m->object, m->pindex,
1984 vm_page_flag_clear(m, PG_SWAPPED);
1985 vm_object_drop(m->object);
1986 if (m->object->type == OBJT_SWAP) {
1988 vm_page_activate(m);
1990 vm_page_io_finish(m);
1991 atomic_clear_int(&m->busy_count,
1995 } else if (bio->bio_caller_info1.index & SWBIO_READ) {
1997 * NOTE: for reads, m->dirty will probably be
1998 * overridden by the original caller of getpages so
1999 * we cannot set them in order to free the underlying
2000 * swap in a low-swap situation. I don't think we'd
2001 * want to do that anyway, but it was an optimization
2002 * that existed in the old swapper for a time before
2003 * it got ripped out due to precisely this problem.
2005 * If not the requested page then deactivate it.
2007 * Note that the requested page, reqpage, is left
2008 * busied, but we still have to wake it up. The
2009 * other pages are released (unbusied) by
2010 * vm_page_wakeup(). We do not set reqpage's
2011 * valid bits here, it is up to the caller.
2015 * NOTE: Can't call pmap_clear_modify(m) from an
2016 * interrupt thread, the pmap code may have to
2017 * map non-kernel pmaps and currently asserts
2020 * WARNING! The instant SWAPINPROG is
2021 * cleared another cpu may start
2022 * using the mreq page (it will
2023 * check m->valid immediately).
2025 /*pmap_clear_modify(m);*/
2026 m->valid = VM_PAGE_BITS_ALL;
2028 vm_page_flag_set(m, PG_SWAPPED);
2029 atomic_clear_int(&m->busy_count, PBUSY_SWAPINPROG);
2032 * We have to wake specifically requested pages
2033 * up too because we cleared SWAPINPROG and
2034 * could be waiting for it in getpages. However,
2035 * be sure to not unbusy getpages specifically
2036 * requested page - getpages expects it to be
2039 * bio_driver_info holds the requested page
2041 if (i != (int)(intptr_t)bio->bio_driver_info) {
2042 vm_page_deactivate(m);
2049 * Mark the page clean but do not mess with the
2050 * pmap-layer's modified state. That state should
2051 * also be clear since the caller protected the
2052 * page VM_PROT_READ, but allow the case.
2054 * We are in an interrupt, avoid pmap operations.
2056 * If we have a severe page deficit, deactivate the
2057 * page. Do not try to cache it (which would also
2058 * involve a pmap op), because the page might still
2061 * When using the swap to cache clean vnode pages
2062 * we do not mess with the page dirty bits.
2064 * NOTE! Nobody is waiting for the key mreq page
2065 * on write completion.
2067 vm_page_busy_wait(m, FALSE, "swadpg");
2068 if (m->object->type == OBJT_SWAP)
2070 vm_page_flag_set(m, PG_SWAPPED);
2071 atomic_clear_int(&m->busy_count, PBUSY_SWAPINPROG);
2072 if (vm_paging_severe())
2073 vm_page_deactivate(m);
2074 vm_page_io_finish(m);
2075 if (bio->bio_caller_info1.index & SWBIO_TTC)
2076 vm_page_try_to_cache(m);
2083 * adjust pip. NOTE: the original parent may still have its own
2084 * pip refs on the object.
2088 vm_object_pip_wakeup_n(object, bp->b_xio.xio_npages);
2091 * Release the physical I/O buffer.
2093 * NOTE: Due to synchronous operations in the write case b_cmd may
2094 * already be set to BUF_CMD_DONE and BIO_SYNC may have already
2097 * Use vm_token to interlock nsw_rcount/wcount wakeup?
2099 lwkt_gettoken(&vm_token);
2100 if (bio->bio_caller_info1.index & SWBIO_READ)
2101 nswptr = &nsw_rcount;
2102 else if (bio->bio_caller_info1.index & SWBIO_SYNC)
2103 nswptr = &nsw_wcount_sync;
2105 nswptr = &nsw_wcount_async;
2106 bp->b_cmd = BUF_CMD_DONE;
2107 relpbuf(bp, nswptr);
2108 lwkt_reltoken(&vm_token);
2112 * Fault-in a potentially swapped page and remove the swap reference.
2113 * (used by swapoff code)
2115 * object must be held.
2117 static __inline void
2118 swp_pager_fault_page(vm_object_t object, int *sharedp, vm_pindex_t pindex)
2124 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
2126 if (object->type == OBJT_VNODE) {
2128 * Any swap related to a vnode is due to swapcache. We must
2129 * vget() the vnode in case it is not active (otherwise
2130 * vref() will panic). Calling vm_object_page_remove() will
2131 * ensure that any swap ref is removed interlocked with the
2132 * page. clean_only is set to TRUE so we don't throw away
2135 vp = object->handle;
2136 error = vget(vp, LK_SHARED | LK_RETRY | LK_CANRECURSE);
2138 vm_object_page_remove(object, pindex, pindex + 1, TRUE);
2143 * Otherwise it is a normal OBJT_SWAP object and we can
2144 * fault the page in and remove the swap.
2146 m = vm_fault_object_page(object, IDX_TO_OFF(pindex),
2148 VM_FAULT_DIRTY | VM_FAULT_UNSWAP,
2156 * This removes all swap blocks related to a particular device. We have
2157 * to be careful of ripups during the scan.
2159 static int swp_pager_swapoff_callback(struct swblock *swap, void *data);
2162 swap_pager_swapoff(int devidx)
2164 struct vm_object_hash *hash;
2165 struct swswapoffinfo info;
2166 struct vm_object marker;
2170 bzero(&marker, sizeof(marker));
2171 marker.type = OBJT_MARKER;
2173 for (n = 0; n < VMOBJ_HSIZE; ++n) {
2174 hash = &vm_object_hash[n];
2176 lwkt_gettoken(&hash->token);
2177 TAILQ_INSERT_HEAD(&hash->list, &marker, object_entry);
2179 while ((object = TAILQ_NEXT(&marker, object_entry)) != NULL) {
2180 if (object->type == OBJT_MARKER)
2182 if (object->type != OBJT_SWAP &&
2183 object->type != OBJT_VNODE)
2185 vm_object_hold(object);
2186 if (object->type != OBJT_SWAP &&
2187 object->type != OBJT_VNODE) {
2188 vm_object_drop(object);
2193 * Object is special in that we can't just pagein
2194 * into vm_page's in it (tmpfs, vn).
2196 if ((object->flags & OBJ_NOPAGEIN) &&
2197 RB_ROOT(&object->swblock_root)) {
2198 vm_object_drop(object);
2202 info.object = object;
2204 info.devidx = devidx;
2205 swblock_rb_tree_RB_SCAN(&object->swblock_root,
2206 NULL, swp_pager_swapoff_callback,
2208 vm_object_drop(object);
2210 if (object == TAILQ_NEXT(&marker, object_entry)) {
2211 TAILQ_REMOVE(&hash->list, &marker,
2213 TAILQ_INSERT_AFTER(&hash->list, object,
2214 &marker, object_entry);
2217 TAILQ_REMOVE(&hash->list, &marker, object_entry);
2218 lwkt_reltoken(&hash->token);
2222 * If we fail to locate all swblocks we just fail gracefully and
2223 * do not bother to restore paging on the swap device. If the
2224 * user wants to retry the user can retry.
2226 if (swdevt[devidx].sw_nused)
2234 swp_pager_swapoff_callback(struct swblock *swap, void *data)
2236 struct swswapoffinfo *info = data;
2237 vm_object_t object = info->object;
2242 index = swap->swb_index;
2243 for (i = 0; i < SWAP_META_PAGES; ++i) {
2245 * Make sure we don't race a dying object. This will
2246 * kill the scan of the object's swap blocks entirely.
2248 if (object->flags & OBJ_DEAD)
2252 * Fault the page, which can obviously block. If the swap
2253 * structure disappears break out.
2255 v = swap->swb_pages[i];
2256 if (v != SWAPBLK_NONE && BLK2DEVIDX(v) == info->devidx) {
2257 swp_pager_fault_page(object, &info->shared,
2258 swap->swb_index + i);
2259 /* swap ptr might go away */
2260 if (RB_LOOKUP(swblock_rb_tree,
2261 &object->swblock_root, index) != swap) {
2269 /************************************************************************
2271 ************************************************************************
2273 * These routines manipulate the swap metadata stored in the
2276 * Swap metadata is implemented with a global hash and not directly
2277 * linked into the object. Instead the object simply contains
2278 * appropriate tracking counters.
2282 * Lookup the swblock containing the specified swap block index.
2284 * The caller must hold the object.
2288 swp_pager_lookup(vm_object_t object, vm_pindex_t index)
2290 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
2291 index &= ~(vm_pindex_t)SWAP_META_MASK;
2292 return (RB_LOOKUP(swblock_rb_tree, &object->swblock_root, index));
2296 * Remove a swblock from the RB tree.
2298 * The caller must hold the object.
2302 swp_pager_remove(vm_object_t object, struct swblock *swap)
2304 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
2305 RB_REMOVE(swblock_rb_tree, &object->swblock_root, swap);
2309 * Convert default object to swap object if necessary
2311 * The caller must hold the object.
2314 swp_pager_meta_convert(vm_object_t object)
2316 if (object->type == OBJT_DEFAULT) {
2317 object->type = OBJT_SWAP;
2318 KKASSERT(object->swblock_count == 0);
2323 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object
2325 * We first convert the object to a swap object if it is a default
2326 * object. Vnode objects do not need to be converted.
2328 * The specified swapblk is added to the object's swap metadata. If
2329 * the swapblk is not valid, it is freed instead. Any previously
2330 * assigned swapblk is freed.
2332 * The caller must hold the object.
2335 swp_pager_meta_build(vm_object_t object, vm_pindex_t index, swblk_t swapblk)
2337 struct swblock *swap;
2338 struct swblock *oswap;
2341 KKASSERT(swapblk != SWAPBLK_NONE);
2342 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
2345 * Convert object if necessary
2347 if (object->type == OBJT_DEFAULT)
2348 swp_pager_meta_convert(object);
2351 * Locate swblock. If not found create, but if we aren't adding
2352 * anything just return. If we run out of space in the map we wait
2353 * and, since the hash table may have changed, retry.
2356 swap = swp_pager_lookup(object, index);
2361 swap = zalloc(swap_zone);
2366 swap->swb_index = index & ~(vm_pindex_t)SWAP_META_MASK;
2367 swap->swb_count = 0;
2369 ++object->swblock_count;
2371 for (i = 0; i < SWAP_META_PAGES; ++i)
2372 swap->swb_pages[i] = SWAPBLK_NONE;
2373 oswap = RB_INSERT(swblock_rb_tree, &object->swblock_root, swap);
2374 KKASSERT(oswap == NULL);
2378 * Delete prior contents of metadata.
2380 * NOTE: Decrement swb_count after the freeing operation (which
2381 * might block) to prevent racing destruction of the swblock.
2383 index &= SWAP_META_MASK;
2385 while ((v = swap->swb_pages[index]) != SWAPBLK_NONE) {
2386 swap->swb_pages[index] = SWAPBLK_NONE;
2388 swp_pager_freeswapspace(object, v, 1);
2390 --mycpu->gd_vmtotal.t_vm;
2394 * Enter block into metadata
2396 swap->swb_pages[index] = swapblk;
2397 if (swapblk != SWAPBLK_NONE) {
2399 ++mycpu->gd_vmtotal.t_vm;
2404 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata
2406 * The requested range of blocks is freed, with any associated swap
2407 * returned to the swap bitmap.
2409 * This routine will free swap metadata structures as they are cleaned
2410 * out. This routine does *NOT* operate on swap metadata associated
2411 * with resident pages.
2413 * The caller must hold the object.
2415 static int swp_pager_meta_free_callback(struct swblock *swb, void *data);
2418 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, vm_pindex_t count)
2420 struct swfreeinfo info;
2422 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
2427 if (object->swblock_count == 0) {
2428 KKASSERT(RB_EMPTY(&object->swblock_root));
2435 * Setup for RB tree scan. Note that the pindex range can be huge
2436 * due to the 64 bit page index space so we cannot safely iterate.
2438 info.object = object;
2439 info.basei = index & ~(vm_pindex_t)SWAP_META_MASK;
2441 info.endi = index + count - 1;
2442 swblock_rb_tree_RB_SCAN(&object->swblock_root, rb_swblock_scancmp,
2443 swp_pager_meta_free_callback, &info);
2447 * The caller must hold the object.
2451 swp_pager_meta_free_callback(struct swblock *swap, void *data)
2453 struct swfreeinfo *info = data;
2454 vm_object_t object = info->object;
2459 * Figure out the range within the swblock. The wider scan may
2460 * return edge-case swap blocks when the start and/or end points
2461 * are in the middle of a block.
2463 if (swap->swb_index < info->begi)
2464 index = (int)info->begi & SWAP_META_MASK;
2468 if (swap->swb_index + SWAP_META_PAGES > info->endi)
2469 eindex = (int)info->endi & SWAP_META_MASK;
2471 eindex = SWAP_META_MASK;
2474 * Scan and free the blocks. The loop terminates early
2475 * if (swap) runs out of blocks and could be freed.
2477 * NOTE: Decrement swb_count after swp_pager_freeswapspace()
2478 * to deal with a zfree race.
2480 while (index <= eindex) {
2481 swblk_t v = swap->swb_pages[index];
2483 if (v != SWAPBLK_NONE) {
2484 swap->swb_pages[index] = SWAPBLK_NONE;
2486 swp_pager_freeswapspace(object, v, 1);
2487 --mycpu->gd_vmtotal.t_vm;
2488 if (--swap->swb_count == 0) {
2489 swp_pager_remove(object, swap);
2490 zfree(swap_zone, swap);
2491 --object->swblock_count;
2498 /* swap may be invalid here due to zfree above */
2505 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object
2507 * This routine locates and destroys all swap metadata associated with
2510 * NOTE: Decrement swb_count after the freeing operation (which
2511 * might block) to prevent racing destruction of the swblock.
2513 * The caller must hold the object.
2516 swp_pager_meta_free_all(vm_object_t object)
2518 struct swblock *swap;
2521 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
2523 while ((swap = RB_ROOT(&object->swblock_root)) != NULL) {
2524 swp_pager_remove(object, swap);
2525 for (i = 0; i < SWAP_META_PAGES; ++i) {
2526 swblk_t v = swap->swb_pages[i];
2527 if (v != SWAPBLK_NONE) {
2529 swp_pager_freeswapspace(object, v, 1);
2531 --mycpu->gd_vmtotal.t_vm;
2534 if (swap->swb_count != 0)
2535 panic("swap_pager_meta_free_all: swb_count != 0");
2536 zfree(swap_zone, swap);
2537 --object->swblock_count;
2540 KKASSERT(object->swblock_count == 0);
2544 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data.
2546 * This routine is capable of looking up, popping, or freeing
2547 * swapblk assignments in the swap meta data or in the vm_page_t.
2548 * The routine typically returns the swapblk being looked-up, or popped,
2549 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block
2550 * was invalid. This routine will automatically free any invalid
2551 * meta-data swapblks.
2553 * It is not possible to store invalid swapblks in the swap meta data
2554 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking.
2556 * When acting on a busy resident page and paging is in progress, we
2557 * have to wait until paging is complete but otherwise can act on the
2560 * SWM_FREE remove and free swap block from metadata
2561 * SWM_POP remove from meta data but do not free.. pop it out
2563 * The caller must hold the object.
2566 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t index, int flags)
2568 struct swblock *swap;
2571 if (object->swblock_count == 0)
2572 return(SWAPBLK_NONE);
2575 swap = swp_pager_lookup(object, index);
2578 index &= SWAP_META_MASK;
2579 r1 = swap->swb_pages[index];
2581 if (r1 != SWAPBLK_NONE) {
2582 if (flags & (SWM_FREE|SWM_POP)) {
2583 swap->swb_pages[index] = SWAPBLK_NONE;
2584 --mycpu->gd_vmtotal.t_vm;
2585 if (--swap->swb_count == 0) {
2586 swp_pager_remove(object, swap);
2587 zfree(swap_zone, swap);
2588 --object->swblock_count;
2591 /* swap ptr may be invalid */
2592 if (flags & SWM_FREE) {
2593 swp_pager_freeswapspace(object, r1, 1);
2597 /* swap ptr may be invalid */