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 $
97 #include <sys/param.h>
98 #include <sys/systm.h>
100 #include <sys/kernel.h>
101 #include <sys/proc.h>
103 #include <sys/vnode.h>
104 #include <sys/malloc.h>
105 #include <sys/vmmeter.h>
106 #include <sys/sysctl.h>
107 #include <sys/blist.h>
108 #include <sys/lock.h>
109 #include <sys/thread2.h>
112 #include "opt_swap.h"
114 #include <vm/vm_object.h>
115 #include <vm/vm_page.h>
116 #include <vm/vm_pager.h>
117 #include <vm/vm_pageout.h>
118 #include <vm/swap_pager.h>
119 #include <vm/vm_extern.h>
120 #include <vm/vm_zone.h>
121 #include <vm/vnode_pager.h>
123 #include <sys/buf2.h>
124 #include <vm/vm_page2.h>
126 #ifndef MAX_PAGEOUT_CLUSTER
127 #define MAX_PAGEOUT_CLUSTER SWB_NPAGES
130 #define SWM_FREE 0x02 /* free, period */
131 #define SWM_POP 0x04 /* pop out */
133 #define SWBIO_READ 0x01
134 #define SWBIO_WRITE 0x02
135 #define SWBIO_SYNC 0x04
136 #define SWBIO_TTC 0x08 /* for VM_PAGER_TRY_TO_CACHE */
142 vm_pindex_t endi
; /* inclusive */
145 struct swswapoffinfo
{
152 * vm_swap_size is in page-sized chunks now. It was DEV_BSIZE'd chunks
156 int swap_pager_full
; /* swap space exhaustion (task killing) */
157 int swap_fail_ticks
; /* when we became exhausted */
158 int swap_pager_almost_full
; /* swap space exhaustion (w/ hysteresis)*/
159 swblk_t vm_swap_cache_use
;
160 swblk_t vm_swap_anon_use
;
161 static int vm_report_swap_allocs
;
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_size
,
197 CTLFLAG_RD
, &vm_swap_size
, 0, "");
199 SYSCTL_INT(_vm
, OID_AUTO
, swap_cache_use
,
200 CTLFLAG_RD
, &vm_swap_cache_use
, 0, "");
201 SYSCTL_INT(_vm
, OID_AUTO
, swap_anon_use
,
202 CTLFLAG_RD
, &vm_swap_anon_use
, 0, "");
203 SYSCTL_INT(_vm
, OID_AUTO
, swap_size
,
204 CTLFLAG_RD
, &vm_swap_size
, 0, "");
206 SYSCTL_INT(_vm
, OID_AUTO
, report_swap_allocs
,
207 CTLFLAG_RW
, &vm_report_swap_allocs
, 0, "");
212 * Red-Black tree for swblock entries
214 * The caller must hold vm_token
216 RB_GENERATE2(swblock_rb_tree
, swblock
, swb_entry
, rb_swblock_compare
,
217 vm_pindex_t
, swb_index
);
220 rb_swblock_compare(struct swblock
*swb1
, struct swblock
*swb2
)
222 if (swb1
->swb_index
< swb2
->swb_index
)
224 if (swb1
->swb_index
> swb2
->swb_index
)
231 rb_swblock_scancmp(struct swblock
*swb
, void *data
)
233 struct swfreeinfo
*info
= data
;
235 if (swb
->swb_index
< info
->basei
)
237 if (swb
->swb_index
> info
->endi
)
244 rb_swblock_condcmp(struct swblock
*swb
, void *data
)
246 struct swfreeinfo
*info
= data
;
248 if (swb
->swb_index
< info
->basei
)
254 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure
255 * calls hooked from other parts of the VM system and do not appear here.
256 * (see vm/swap_pager.h).
259 static void swap_pager_dealloc (vm_object_t object
);
260 static int swap_pager_getpage (vm_object_t
, vm_page_t
*, int);
261 static void swap_chain_iodone(struct bio
*biox
);
263 struct pagerops swappagerops
= {
264 swap_pager_dealloc
, /* deallocate an OBJT_SWAP object */
265 swap_pager_getpage
, /* pagein */
266 swap_pager_putpages
, /* pageout */
267 swap_pager_haspage
/* get backing store status for page */
271 * SWB_DMMAX is in page-sized chunks with the new swap system. It was
272 * dev-bsized chunks in the old. SWB_DMMAX is always a power of 2.
274 * swap_*() routines are externally accessible. swp_*() routines are
278 int nswap_lowat
= 128; /* in pages, swap_pager_almost_full warn */
279 int nswap_hiwat
= 512; /* in pages, swap_pager_almost_full warn */
281 static __inline
void swp_sizecheck (void);
282 static void swp_pager_async_iodone (struct bio
*bio
);
285 * Swap bitmap functions
288 static __inline
void swp_pager_freeswapspace(vm_object_t object
,
289 swblk_t blk
, int npages
);
290 static __inline swblk_t
swp_pager_getswapspace(vm_object_t object
, int npages
);
296 static void swp_pager_meta_convert(vm_object_t
);
297 static void swp_pager_meta_build(vm_object_t
, vm_pindex_t
, swblk_t
);
298 static void swp_pager_meta_free(vm_object_t
, vm_pindex_t
, vm_pindex_t
);
299 static void swp_pager_meta_free_all(vm_object_t
);
300 static swblk_t
swp_pager_meta_ctl(vm_object_t
, vm_pindex_t
, int);
303 * SWP_SIZECHECK() - update swap_pager_full indication
305 * update the swap_pager_almost_full indication and warn when we are
306 * about to run out of swap space, using lowat/hiwat hysteresis.
308 * Clear swap_pager_full ( task killing ) indication when lowat is met.
310 * No restrictions on call
311 * This routine may not block.
317 if (vm_swap_size
< nswap_lowat
) {
318 if (swap_pager_almost_full
== 0) {
319 kprintf("swap_pager: out of swap space\n");
320 swap_pager_almost_full
= 1;
321 swap_fail_ticks
= ticks
;
325 if (vm_swap_size
> nswap_hiwat
)
326 swap_pager_almost_full
= 0;
331 * SWAP_PAGER_INIT() - initialize the swap pager!
333 * Expected to be started from system init. NOTE: This code is run
334 * before much else so be careful what you depend on. Most of the VM
335 * system has yet to be initialized at this point.
337 * Called from the low level boot code only.
340 swap_pager_init(void *arg __unused
)
343 SYSINIT(vm_mem
, SI_BOOT1_VM
, SI_ORDER_THIRD
, swap_pager_init
, NULL
);
346 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process
348 * Expected to be started from pageout process once, prior to entering
351 * Called from the low level boot code only.
354 swap_pager_swap_init(void)
359 * Number of in-transit swap bp operations. Don't
360 * exhaust the pbufs completely. Make sure we
361 * initialize workable values (0 will work for hysteresis
362 * but it isn't very efficient).
364 * The nsw_cluster_max is constrained by the number of pages an XIO
365 * holds, i.e., (MAXPHYS/PAGE_SIZE) and our locally defined
366 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are
367 * constrained by the swap device interleave stripe size.
369 * Currently we hardwire nsw_wcount_async to 4. This limit is
370 * designed to prevent other I/O from having high latencies due to
371 * our pageout I/O. The value 4 works well for one or two active swap
372 * devices but is probably a little low if you have more. Even so,
373 * a higher value would probably generate only a limited improvement
374 * with three or four active swap devices since the system does not
375 * typically have to pageout at extreme bandwidths. We will want
376 * at least 2 per swap devices, and 4 is a pretty good value if you
377 * have one NFS swap device due to the command/ack latency over NFS.
378 * So it all works out pretty well.
381 nsw_cluster_max
= min((MAXPHYS
/PAGE_SIZE
), MAX_PAGEOUT_CLUSTER
);
383 nsw_rcount
= (nswbuf_kva
+ 1) / 2;
384 nsw_wcount_sync
= (nswbuf_kva
+ 3) / 4;
385 nsw_wcount_async
= 4;
386 nsw_wcount_async_max
= nsw_wcount_async
;
389 * The zone is dynamically allocated so generally size it to
390 * maxswzone (32MB to 256GB of KVM). Set a minimum size based
391 * on physical memory of around 8x (each swblock can hold 16 pages).
393 * With the advent of SSDs (vs HDs) the practical (swap:memory) ratio
394 * has increased dramatically.
396 n
= vmstats
.v_page_count
/ 2;
397 if (maxswzone
&& n
< maxswzone
/ sizeof(struct swblock
))
398 n
= maxswzone
/ sizeof(struct swblock
);
404 sizeof(struct swblock
),
407 if (swap_zone
!= NULL
)
410 * if the allocation failed, try a zone two thirds the
411 * size of the previous attempt.
416 if (swap_zone
== NULL
)
417 panic("swap_pager_swap_init: swap_zone == NULL");
419 kprintf("Swap zone entries reduced from %d to %d.\n", n2
, n
);
423 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate
424 * its metadata structures.
426 * This routine is called from the mmap and fork code to create a new
427 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object
428 * and then converting it with swp_pager_meta_convert().
430 * We only support unnamed objects.
435 swap_pager_alloc(void *handle
, off_t size
, vm_prot_t prot
, off_t offset
)
439 KKASSERT(handle
== NULL
);
440 object
= vm_object_allocate_hold(OBJT_DEFAULT
,
441 OFF_TO_IDX(offset
+ PAGE_MASK
+ size
));
442 swp_pager_meta_convert(object
);
443 vm_object_drop(object
);
449 * SWAP_PAGER_DEALLOC() - remove swap metadata from object
451 * The swap backing for the object is destroyed. The code is
452 * designed such that we can reinstantiate it later, but this
453 * routine is typically called only when the entire object is
454 * about to be destroyed.
456 * The object must be locked or unreferenceable.
457 * No other requirements.
460 swap_pager_dealloc(vm_object_t object
)
462 vm_object_hold(object
);
463 vm_object_pip_wait(object
, "swpdea");
466 * Free all remaining metadata. We only bother to free it from
467 * the swap meta data. We do not attempt to free swapblk's still
468 * associated with vm_page_t's for this object. We do not care
469 * if paging is still in progress on some objects.
471 swp_pager_meta_free_all(object
);
472 vm_object_drop(object
);
475 /************************************************************************
476 * SWAP PAGER BITMAP ROUTINES *
477 ************************************************************************/
480 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space
482 * Allocate swap for the requested number of pages. The starting
483 * swap block number (a page index) is returned or SWAPBLK_NONE
484 * if the allocation failed.
486 * Also has the side effect of advising that somebody made a mistake
487 * when they configured swap and didn't configure enough.
489 * The caller must hold the object.
490 * This routine may not block.
492 static __inline swblk_t
493 swp_pager_getswapspace(vm_object_t object
, int npages
)
497 lwkt_gettoken(&vm_token
);
498 blk
= blist_allocat(swapblist
, npages
, swapiterator
);
499 if (blk
== SWAPBLK_NONE
)
500 blk
= blist_allocat(swapblist
, npages
, 0);
501 if (blk
== SWAPBLK_NONE
) {
502 if (swap_pager_full
!= 2) {
503 if (vm_swap_max
== 0)
504 kprintf("Warning: The system would like to "
505 "page to swap but no swap space "
508 kprintf("swap_pager_getswapspace: "
509 "swap full allocating %d pages\n",
512 if (swap_pager_almost_full
== 0)
513 swap_fail_ticks
= ticks
;
514 swap_pager_almost_full
= 1;
517 /* swapiterator = blk; disable for now, doesn't work well */
518 swapacctspace(blk
, -npages
);
519 if (object
->type
== OBJT_SWAP
)
520 vm_swap_anon_use
+= npages
;
522 vm_swap_cache_use
+= npages
;
525 lwkt_reltoken(&vm_token
);
530 * SWP_PAGER_FREESWAPSPACE() - free raw swap space
532 * This routine returns the specified swap blocks back to the bitmap.
534 * Note: This routine may not block (it could in the old swap code),
535 * and through the use of the new blist routines it does not block.
537 * This routine may not block.
541 swp_pager_freeswapspace(vm_object_t object
, swblk_t blk
, int npages
)
543 struct swdevt
*sp
= &swdevt
[BLK2DEVIDX(blk
)];
545 lwkt_gettoken(&vm_token
);
546 sp
->sw_nused
-= npages
;
547 if (object
->type
== OBJT_SWAP
)
548 vm_swap_anon_use
-= npages
;
550 vm_swap_cache_use
-= npages
;
552 if (sp
->sw_flags
& SW_CLOSING
) {
553 lwkt_reltoken(&vm_token
);
557 blist_free(swapblist
, blk
, npages
);
558 vm_swap_size
+= npages
;
560 lwkt_reltoken(&vm_token
);
564 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page
565 * range within an object.
567 * This is a globally accessible routine.
569 * This routine removes swapblk assignments from swap metadata.
571 * The external callers of this routine typically have already destroyed
572 * or renamed vm_page_t's associated with this range in the object so
578 swap_pager_freespace(vm_object_t object
, vm_pindex_t start
, vm_pindex_t size
)
580 vm_object_hold(object
);
581 swp_pager_meta_free(object
, start
, size
);
582 vm_object_drop(object
);
589 swap_pager_freespace_all(vm_object_t object
)
591 vm_object_hold(object
);
592 swp_pager_meta_free_all(object
);
593 vm_object_drop(object
);
597 * This function conditionally frees swap cache swap starting at
598 * (*basei) in the object. (count) swap blocks will be nominally freed.
599 * The actual number of blocks freed can be more or less than the
602 * This function nominally returns the number of blocks freed. However,
603 * the actual number of blocks freed may be less then the returned value.
604 * If the function is unable to exhaust the object or if it is able to
605 * free (approximately) the requested number of blocks it returns
608 * If we exhaust the object we will return a value n <= count.
610 * The caller must hold the object.
612 * WARNING! If count == 0 then -1 can be returned as a degenerate case,
613 * callers should always pass a count value > 0.
615 static int swap_pager_condfree_callback(struct swblock
*swap
, void *data
);
618 swap_pager_condfree(vm_object_t object
, vm_pindex_t
*basei
, int count
)
620 struct swfreeinfo info
;
624 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
626 info
.object
= object
;
627 info
.basei
= *basei
; /* skip up to this page index */
628 info
.begi
= count
; /* max swap pages to destroy */
629 info
.endi
= count
* 8; /* max swblocks to scan */
631 swblock_rb_tree_RB_SCAN(&object
->swblock_root
, rb_swblock_condcmp
,
632 swap_pager_condfree_callback
, &info
);
636 * Take the higher difference swblocks vs pages
638 n
= count
- (int)info
.begi
;
639 t
= count
* 8 - (int)info
.endi
;
648 * The idea is to free whole meta-block to avoid fragmenting
649 * the swap space or disk I/O. We only do this if NO VM pages
652 * We do not have to deal with clearing PG_SWAPPED in related VM
653 * pages because there are no related VM pages.
655 * The caller must hold the object.
658 swap_pager_condfree_callback(struct swblock
*swap
, void *data
)
660 struct swfreeinfo
*info
= data
;
661 vm_object_t object
= info
->object
;
664 for (i
= 0; i
< SWAP_META_PAGES
; ++i
) {
665 if (vm_page_lookup(object
, swap
->swb_index
+ i
))
668 info
->basei
= swap
->swb_index
+ SWAP_META_PAGES
;
669 if (i
== SWAP_META_PAGES
) {
670 info
->begi
-= swap
->swb_count
;
671 swap_pager_freespace(object
, swap
->swb_index
, SWAP_META_PAGES
);
674 if ((int)info
->begi
< 0 || (int)info
->endi
< 0)
681 * Called by vm_page_alloc() when a new VM page is inserted
682 * into a VM object. Checks whether swap has been assigned to
683 * the page and sets PG_SWAPPED as necessary.
685 * (m) must be busied by caller and remains busied on return.
688 swap_pager_page_inserted(vm_page_t m
)
690 if (m
->object
->swblock_count
) {
691 vm_object_hold(m
->object
);
692 if (swp_pager_meta_ctl(m
->object
, m
->pindex
, 0) != SWAPBLK_NONE
)
693 vm_page_flag_set(m
, PG_SWAPPED
);
694 vm_object_drop(m
->object
);
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.
706 * The caller is responsible for avoiding races in the specified range.
707 * No other requirements.
710 swap_pager_reserve(vm_object_t object
, vm_pindex_t start
, vm_size_t size
)
713 swblk_t blk
= SWAPBLK_NONE
;
714 vm_pindex_t beg
= start
; /* save start index */
716 vm_object_hold(object
);
721 while ((blk
= swp_pager_getswapspace(object
, n
)) ==
726 swp_pager_meta_free(object
, beg
,
728 vm_object_drop(object
);
733 swp_pager_meta_build(object
, start
, blk
);
739 swp_pager_meta_free(object
, start
, n
);
740 vm_object_drop(object
);
745 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager
746 * and destroy the source.
748 * Copy any valid swapblks from the source to the destination. In
749 * cases where both the source and destination have a valid swapblk,
750 * we keep the destination's.
752 * This routine is allowed to block. It may block allocating metadata
753 * indirectly through swp_pager_meta_build() or if paging is still in
754 * progress on the source.
756 * XXX vm_page_collapse() kinda expects us not to block because we
757 * supposedly do not need to allocate memory, but for the moment we
758 * *may* have to get a little memory from the zone allocator, but
759 * it is taken from the interrupt memory. We should be ok.
761 * The source object contains no vm_page_t's (which is just as well)
762 * The source object is of type OBJT_SWAP.
764 * The source and destination objects must be held by the caller.
767 swap_pager_copy(vm_object_t srcobject
, vm_object_t dstobject
,
768 vm_pindex_t base_index
, int destroysource
)
772 ASSERT_LWKT_TOKEN_HELD(vm_object_token(srcobject
));
773 ASSERT_LWKT_TOKEN_HELD(vm_object_token(dstobject
));
776 * transfer source to destination.
778 for (i
= 0; i
< dstobject
->size
; ++i
) {
782 * Locate (without changing) the swapblk on the destination,
783 * unless it is invalid in which case free it silently, or
784 * if the destination is a resident page, in which case the
785 * source is thrown away.
787 dstaddr
= swp_pager_meta_ctl(dstobject
, i
, 0);
789 if (dstaddr
== SWAPBLK_NONE
) {
791 * Destination has no swapblk and is not resident,
796 srcaddr
= swp_pager_meta_ctl(srcobject
,
797 base_index
+ i
, SWM_POP
);
799 if (srcaddr
!= SWAPBLK_NONE
)
800 swp_pager_meta_build(dstobject
, i
, srcaddr
);
803 * Destination has valid swapblk or it is represented
804 * by a resident page. We destroy the sourceblock.
806 swp_pager_meta_ctl(srcobject
, base_index
+ i
, SWM_FREE
);
811 * Free left over swap blocks in source.
813 * We have to revert the type to OBJT_DEFAULT so we do not accidently
814 * double-remove the object from the swap queues.
818 * Reverting the type is not necessary, the caller is going
819 * to destroy srcobject directly, but I'm doing it here
820 * for consistency since we've removed the object from its
823 swp_pager_meta_free_all(srcobject
);
824 if (srcobject
->type
== OBJT_SWAP
)
825 srcobject
->type
= OBJT_DEFAULT
;
830 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for
831 * the requested page.
833 * We determine whether good backing store exists for the requested
834 * page and return TRUE if it does, FALSE if it doesn't.
836 * If TRUE, we also try to determine how much valid, contiguous backing
837 * store exists before and after the requested page within a reasonable
838 * distance. We do not try to restrict it to the swap device stripe
839 * (that is handled in getpages/putpages). It probably isn't worth
845 swap_pager_haspage(vm_object_t object
, vm_pindex_t pindex
)
850 * do we have good backing store at the requested index ?
852 vm_object_hold(object
);
853 blk0
= swp_pager_meta_ctl(object
, pindex
, 0);
855 if (blk0
== SWAPBLK_NONE
) {
856 vm_object_drop(object
);
859 vm_object_drop(object
);
864 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page
866 * This removes any associated swap backing store, whether valid or
867 * not, from the page. This operates on any VM object, not just OBJT_SWAP
870 * This routine is typically called when a page is made dirty, at
871 * which point any associated swap can be freed. MADV_FREE also
872 * calls us in a special-case situation
874 * NOTE!!! If the page is clean and the swap was valid, the caller
875 * should make the page dirty before calling this routine.
876 * This routine does NOT change the m->dirty status of the page.
877 * Also: MADV_FREE depends on it.
879 * The page must be busied.
880 * The caller can hold the object to avoid blocking, else we might block.
881 * No other requirements.
884 swap_pager_unswapped(vm_page_t m
)
886 if (m
->flags
& PG_SWAPPED
) {
887 vm_object_hold(m
->object
);
888 KKASSERT(m
->flags
& PG_SWAPPED
);
889 swp_pager_meta_ctl(m
->object
, m
->pindex
, SWM_FREE
);
890 vm_page_flag_clear(m
, PG_SWAPPED
);
891 vm_object_drop(m
->object
);
896 * SWAP_PAGER_STRATEGY() - read, write, free blocks
898 * This implements a VM OBJECT strategy function using swap backing store.
899 * This can operate on any VM OBJECT type, not necessarily just OBJT_SWAP
902 * This is intended to be a cacheless interface (i.e. caching occurs at
903 * higher levels), and is also used as a swap-based SSD cache for vnode
904 * and device objects.
906 * All I/O goes directly to and from the swap device.
908 * We currently attempt to run I/O synchronously or asynchronously as
909 * the caller requests. This isn't perfect because we loose error
910 * sequencing when we run multiple ops in parallel to satisfy a request.
911 * But this is swap, so we let it all hang out.
916 swap_pager_strategy(vm_object_t object
, struct bio
*bio
)
918 struct buf
*bp
= bio
->bio_buf
;
921 vm_pindex_t biox_blkno
= 0;
927 struct bio_track
*track
;
932 * tracking for swapdev vnode I/Os
934 if (bp
->b_cmd
== BUF_CMD_READ
)
935 track
= &swapdev_vp
->v_track_read
;
937 track
= &swapdev_vp
->v_track_write
;
940 if (bp
->b_bcount
& PAGE_MASK
) {
941 bp
->b_error
= EINVAL
;
942 bp
->b_flags
|= B_ERROR
| B_INVAL
;
944 kprintf("swap_pager_strategy: bp %p offset %lld size %d, "
945 "not page bounded\n",
946 bp
, (long long)bio
->bio_offset
, (int)bp
->b_bcount
);
951 * Clear error indication, initialize page index, count, data pointer.
954 bp
->b_flags
&= ~B_ERROR
;
955 bp
->b_resid
= bp
->b_bcount
;
957 start
= (vm_pindex_t
)(bio
->bio_offset
>> PAGE_SHIFT
);
958 count
= howmany(bp
->b_bcount
, PAGE_SIZE
);
962 * Deal with BUF_CMD_FREEBLKS
964 if (bp
->b_cmd
== BUF_CMD_FREEBLKS
) {
966 * FREE PAGE(s) - destroy underlying swap that is no longer
969 vm_object_hold(object
);
970 swp_pager_meta_free(object
, start
, count
);
971 vm_object_drop(object
);
978 * We need to be able to create a new cluster of I/O's. We cannot
979 * use the caller fields of the passed bio so push a new one.
981 * Because nbio is just a placeholder for the cluster links,
982 * we can biodone() the original bio instead of nbio to make
983 * things a bit more efficient.
985 nbio
= push_bio(bio
);
986 nbio
->bio_offset
= bio
->bio_offset
;
987 nbio
->bio_caller_info1
.cluster_head
= NULL
;
988 nbio
->bio_caller_info2
.cluster_tail
= NULL
;
994 * Execute read or write
996 vm_object_hold(object
);
1002 * Obtain block. If block not found and writing, allocate a
1003 * new block and build it into the object.
1005 blk
= swp_pager_meta_ctl(object
, start
, 0);
1006 if ((blk
== SWAPBLK_NONE
) && bp
->b_cmd
!= BUF_CMD_READ
) {
1007 blk
= swp_pager_getswapspace(object
, 1);
1008 if (blk
== SWAPBLK_NONE
) {
1009 bp
->b_error
= ENOMEM
;
1010 bp
->b_flags
|= B_ERROR
;
1013 swp_pager_meta_build(object
, start
, blk
);
1017 * Do we have to flush our current collection? Yes if:
1019 * - no swap block at this index
1020 * - swap block is not contiguous
1021 * - we cross a physical disk boundry in the
1025 biox
&& (biox_blkno
+ btoc(bufx
->b_bcount
) != blk
||
1026 ((biox_blkno
^ blk
) & ~SWB_DMMASK
)
1029 if (bp
->b_cmd
== BUF_CMD_READ
) {
1030 ++mycpu
->gd_cnt
.v_swapin
;
1031 mycpu
->gd_cnt
.v_swappgsin
+= btoc(bufx
->b_bcount
);
1033 ++mycpu
->gd_cnt
.v_swapout
;
1034 mycpu
->gd_cnt
.v_swappgsout
+= btoc(bufx
->b_bcount
);
1035 bufx
->b_dirtyend
= bufx
->b_bcount
;
1039 * Finished with this buf.
1041 KKASSERT(bufx
->b_bcount
!= 0);
1042 if (bufx
->b_cmd
!= BUF_CMD_READ
)
1043 bufx
->b_dirtyend
= bufx
->b_bcount
;
1049 * Add new swapblk to biox, instantiating biox if necessary.
1050 * Zero-fill reads are able to take a shortcut.
1052 if (blk
== SWAPBLK_NONE
) {
1054 * We can only get here if we are reading.
1056 bzero(data
, PAGE_SIZE
);
1057 bp
->b_resid
-= PAGE_SIZE
;
1060 /* XXX chain count > 4, wait to <= 4 */
1062 bufx
= getpbuf(NULL
);
1063 biox
= &bufx
->b_bio1
;
1064 cluster_append(nbio
, bufx
);
1065 bufx
->b_cmd
= bp
->b_cmd
;
1066 biox
->bio_done
= swap_chain_iodone
;
1067 biox
->bio_offset
= (off_t
)blk
<< PAGE_SHIFT
;
1068 biox
->bio_caller_info1
.cluster_parent
= nbio
;
1071 bufx
->b_data
= data
;
1073 bufx
->b_bcount
+= PAGE_SIZE
;
1080 vm_object_drop(object
);
1083 * Flush out last buffer
1086 if (bufx
->b_cmd
== BUF_CMD_READ
) {
1087 ++mycpu
->gd_cnt
.v_swapin
;
1088 mycpu
->gd_cnt
.v_swappgsin
+= btoc(bufx
->b_bcount
);
1090 ++mycpu
->gd_cnt
.v_swapout
;
1091 mycpu
->gd_cnt
.v_swappgsout
+= btoc(bufx
->b_bcount
);
1092 bufx
->b_dirtyend
= bufx
->b_bcount
;
1094 KKASSERT(bufx
->b_bcount
);
1095 if (bufx
->b_cmd
!= BUF_CMD_READ
)
1096 bufx
->b_dirtyend
= bufx
->b_bcount
;
1097 /* biox, bufx = NULL */
1101 * Now initiate all the I/O. Be careful looping on our chain as
1102 * I/O's may complete while we are still initiating them.
1104 * If the request is a 100% sparse read no bios will be present
1105 * and we just biodone() the buffer.
1107 nbio
->bio_caller_info2
.cluster_tail
= NULL
;
1108 bufx
= nbio
->bio_caller_info1
.cluster_head
;
1112 biox
= &bufx
->b_bio1
;
1114 bufx
= bufx
->b_cluster_next
;
1115 vn_strategy(swapdev_vp
, biox
);
1122 * Completion of the cluster will also call biodone_chain(nbio).
1123 * We never call biodone(nbio) so we don't have to worry about
1124 * setting up a bio_done callback. It's handled in the sub-IO.
1135 swap_chain_iodone(struct bio
*biox
)
1138 struct buf
*bufx
; /* chained sub-buffer */
1139 struct bio
*nbio
; /* parent nbio with chain glue */
1140 struct buf
*bp
; /* original bp associated with nbio */
1143 bufx
= biox
->bio_buf
;
1144 nbio
= biox
->bio_caller_info1
.cluster_parent
;
1148 * Update the original buffer
1150 KKASSERT(bp
!= NULL
);
1151 if (bufx
->b_flags
& B_ERROR
) {
1152 atomic_set_int(&bufx
->b_flags
, B_ERROR
);
1153 bp
->b_error
= bufx
->b_error
; /* race ok */
1154 } else if (bufx
->b_resid
!= 0) {
1155 atomic_set_int(&bufx
->b_flags
, B_ERROR
);
1156 bp
->b_error
= EINVAL
; /* race ok */
1158 atomic_subtract_int(&bp
->b_resid
, bufx
->b_bcount
);
1162 * Remove us from the chain.
1164 spin_lock(&swapbp_spin
);
1165 nextp
= &nbio
->bio_caller_info1
.cluster_head
;
1166 while (*nextp
!= bufx
) {
1167 KKASSERT(*nextp
!= NULL
);
1168 nextp
= &(*nextp
)->b_cluster_next
;
1170 *nextp
= bufx
->b_cluster_next
;
1171 chain_empty
= (nbio
->bio_caller_info1
.cluster_head
== NULL
);
1172 spin_unlock(&swapbp_spin
);
1175 * Clean up bufx. If the chain is now empty we finish out
1176 * the parent. Note that we may be racing other completions
1177 * so we must use the chain_empty status from above.
1180 if (bp
->b_resid
!= 0 && !(bp
->b_flags
& B_ERROR
)) {
1181 atomic_set_int(&bp
->b_flags
, B_ERROR
);
1182 bp
->b_error
= EINVAL
;
1184 biodone_chain(nbio
);
1186 relpbuf(bufx
, NULL
);
1190 * SWAP_PAGER_GETPAGES() - bring page in from swap
1192 * The requested page may have to be brought in from swap. Calculate the
1193 * swap block and bring in additional pages if possible. All pages must
1194 * have contiguous swap block assignments and reside in the same object.
1196 * The caller has a single vm_object_pip_add() reference prior to
1197 * calling us and we should return with the same.
1199 * The caller has BUSY'd the page. We should return with (*mpp) left busy,
1200 * and any additinal pages unbusied.
1202 * If the caller encounters a PG_RAM page it will pass it to us even though
1203 * it may be valid and dirty. We cannot overwrite the page in this case!
1204 * The case is used to allow us to issue pure read-aheads.
1206 * NOTE! XXX This code does not entirely pipeline yet due to the fact that
1207 * the PG_RAM page is validated at the same time as mreq. What we
1208 * really need to do is issue a separate read-ahead pbuf.
1213 swap_pager_getpage(vm_object_t object
, vm_page_t
*mpp
, int seqaccess
)
1226 vm_page_t marray
[XIO_INTERNAL_PAGES
];
1230 vm_object_hold(object
);
1231 if (mreq
->object
!= object
) {
1232 panic("swap_pager_getpages: object mismatch %p/%p",
1239 * We don't want to overwrite a fully valid page as it might be
1240 * dirty. This case can occur when e.g. vm_fault hits a perfectly
1241 * valid page with PG_RAM set.
1243 * In this case we see if the next page is a suitable page-in
1244 * candidate and if it is we issue read-ahead. PG_RAM will be
1245 * set on the last page of the read-ahead to continue the pipeline.
1247 if (mreq
->valid
== VM_PAGE_BITS_ALL
) {
1248 if (swap_burst_read
== 0 || mreq
->pindex
+ 1 >= object
->size
) {
1249 vm_object_drop(object
);
1250 return(VM_PAGER_OK
);
1252 blk
= swp_pager_meta_ctl(object
, mreq
->pindex
+ 1, 0);
1253 if (blk
== SWAPBLK_NONE
) {
1254 vm_object_drop(object
);
1255 return(VM_PAGER_OK
);
1257 m
= vm_page_lookup_busy_try(object
, mreq
->pindex
+ 1,
1260 vm_object_drop(object
);
1261 return(VM_PAGER_OK
);
1262 } else if (m
== NULL
) {
1264 * Use VM_ALLOC_QUICK to avoid blocking on cache
1267 m
= vm_page_alloc(object
, mreq
->pindex
+ 1,
1270 vm_object_drop(object
);
1271 return(VM_PAGER_OK
);
1276 vm_object_drop(object
);
1277 return(VM_PAGER_OK
);
1279 vm_page_unqueue_nowakeup(m
);
1289 * Try to block-read contiguous pages from swap if sequential,
1290 * otherwise just read one page. Contiguous pages from swap must
1291 * reside within a single device stripe because the I/O cannot be
1292 * broken up across multiple stripes.
1294 * Note that blk and iblk can be SWAPBLK_NONE but the loop is
1295 * set up such that the case(s) are handled implicitly.
1297 blk
= swp_pager_meta_ctl(mreq
->object
, mreq
->pindex
, 0);
1300 for (i
= 1; i
<= swap_burst_read
&&
1301 i
< XIO_INTERNAL_PAGES
&&
1302 mreq
->pindex
+ i
< object
->size
; ++i
) {
1305 iblk
= swp_pager_meta_ctl(object
, mreq
->pindex
+ i
, 0);
1306 if (iblk
!= blk
+ i
)
1308 if ((blk
^ iblk
) & ~SWB_DMMASK
)
1310 m
= vm_page_lookup_busy_try(object
, mreq
->pindex
+ i
,
1314 } else if (m
== NULL
) {
1316 * Use VM_ALLOC_QUICK to avoid blocking on cache
1319 m
= vm_page_alloc(object
, mreq
->pindex
+ i
,
1328 vm_page_unqueue_nowakeup(m
);
1334 vm_page_flag_set(marray
[i
- 1], PG_RAM
);
1337 * If mreq is the requested page and we have nothing to do return
1338 * VM_PAGER_FAIL. If raonly is set mreq is just another read-ahead
1339 * page and must be cleaned up.
1341 if (blk
== SWAPBLK_NONE
) {
1344 vnode_pager_freepage(mreq
);
1345 vm_object_drop(object
);
1346 return(VM_PAGER_OK
);
1348 vm_object_drop(object
);
1349 return(VM_PAGER_FAIL
);
1354 * map our page(s) into kva for input
1356 bp
= getpbuf_kva(&nsw_rcount
);
1358 kva
= (vm_offset_t
) bp
->b_kvabase
;
1359 bcopy(marray
, bp
->b_xio
.xio_pages
, i
* sizeof(vm_page_t
));
1360 pmap_qenter(kva
, bp
->b_xio
.xio_pages
, i
);
1362 bp
->b_data
= (caddr_t
)kva
;
1363 bp
->b_bcount
= PAGE_SIZE
* i
;
1364 bp
->b_xio
.xio_npages
= i
;
1365 bio
->bio_done
= swp_pager_async_iodone
;
1366 bio
->bio_offset
= (off_t
)blk
<< PAGE_SHIFT
;
1367 bio
->bio_caller_info1
.index
= SWBIO_READ
;
1370 * Set index. If raonly set the index beyond the array so all
1371 * the pages are treated the same, otherwise the original mreq is
1375 bio
->bio_driver_info
= (void *)(intptr_t)i
;
1377 bio
->bio_driver_info
= (void *)(intptr_t)0;
1379 for (j
= 0; j
< i
; ++j
)
1380 vm_page_flag_set(bp
->b_xio
.xio_pages
[j
], PG_SWAPINPROG
);
1382 mycpu
->gd_cnt
.v_swapin
++;
1383 mycpu
->gd_cnt
.v_swappgsin
+= bp
->b_xio
.xio_npages
;
1386 * We still hold the lock on mreq, and our automatic completion routine
1387 * does not remove it.
1389 vm_object_pip_add(object
, bp
->b_xio
.xio_npages
);
1392 * perform the I/O. NOTE!!! bp cannot be considered valid after
1393 * this point because we automatically release it on completion.
1394 * Instead, we look at the one page we are interested in which we
1395 * still hold a lock on even through the I/O completion.
1397 * The other pages in our m[] array are also released on completion,
1398 * so we cannot assume they are valid anymore either.
1400 bp
->b_cmd
= BUF_CMD_READ
;
1402 vn_strategy(swapdev_vp
, bio
);
1405 * Wait for the page we want to complete. PG_SWAPINPROG is always
1406 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE
1407 * is set in the meta-data.
1409 * If this is a read-ahead only we return immediately without
1413 vm_object_drop(object
);
1414 return(VM_PAGER_OK
);
1418 * Read-ahead includes originally requested page case.
1421 flags
= mreq
->flags
;
1423 if ((flags
& PG_SWAPINPROG
) == 0)
1425 tsleep_interlock(mreq
, 0);
1426 if (!atomic_cmpset_int(&mreq
->flags
, flags
,
1427 flags
| PG_WANTED
| PG_REFERENCED
)) {
1430 mycpu
->gd_cnt
.v_intrans
++;
1431 if (tsleep(mreq
, PINTERLOCKED
, "swread", hz
*20)) {
1433 "swap_pager: indefinite wait buffer: "
1434 " bp %p offset: %lld, size: %ld\n",
1436 (long long)bio
->bio_offset
,
1443 * Disallow speculative reads prior to the PG_SWAPINPROG test.
1448 * mreq is left busied after completion, but all the other pages
1449 * are freed. If we had an unrecoverable read error the page will
1452 vm_object_drop(object
);
1453 if (mreq
->valid
!= VM_PAGE_BITS_ALL
)
1454 return(VM_PAGER_ERROR
);
1456 return(VM_PAGER_OK
);
1459 * A final note: in a low swap situation, we cannot deallocate swap
1460 * and mark a page dirty here because the caller is likely to mark
1461 * the page clean when we return, causing the page to possibly revert
1462 * to all-zero's later.
1467 * swap_pager_putpages:
1469 * Assign swap (if necessary) and initiate I/O on the specified pages.
1471 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects
1472 * are automatically converted to SWAP objects.
1474 * In a low memory situation we may block in vn_strategy(), but the new
1475 * vm_page reservation system coupled with properly written VFS devices
1476 * should ensure that no low-memory deadlock occurs. This is an area
1479 * The parent has N vm_object_pip_add() references prior to
1480 * calling us and will remove references for rtvals[] that are
1481 * not set to VM_PAGER_PEND. We need to remove the rest on I/O
1484 * The parent has soft-busy'd the pages it passes us and will unbusy
1485 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return.
1486 * We need to unbusy the rest on I/O completion.
1491 swap_pager_putpages(vm_object_t object
, vm_page_t
*m
, int count
,
1492 int flags
, int *rtvals
)
1497 vm_object_hold(object
);
1499 if (count
&& m
[0]->object
!= object
) {
1500 panic("swap_pager_getpages: object mismatch %p/%p",
1509 * Turn object into OBJT_SWAP
1510 * Check for bogus sysops
1512 * Force sync if not pageout process, we don't want any single
1513 * non-pageout process to be able to hog the I/O subsystem! This
1514 * can be overridden by setting.
1516 if (object
->type
== OBJT_DEFAULT
) {
1517 if (object
->type
== OBJT_DEFAULT
)
1518 swp_pager_meta_convert(object
);
1522 * Normally we force synchronous swap I/O if this is not the
1523 * pageout daemon to prevent any single user process limited
1524 * via RLIMIT_RSS from hogging swap write bandwidth.
1526 if (curthread
!= pagethread
&& swap_user_async
== 0)
1527 flags
|= VM_PAGER_PUT_SYNC
;
1532 * Update nsw parameters from swap_async_max sysctl values.
1533 * Do not let the sysop crash the machine with bogus numbers.
1535 if (swap_async_max
!= nsw_wcount_async_max
) {
1541 if ((n
= swap_async_max
) > nswbuf_kva
/ 2)
1548 * Adjust difference ( if possible ). If the current async
1549 * count is too low, we may not be able to make the adjustment
1552 * vm_token needed for nsw_wcount sleep interlock
1554 lwkt_gettoken(&vm_token
);
1555 n
-= nsw_wcount_async_max
;
1556 if (nsw_wcount_async
+ n
>= 0) {
1557 nsw_wcount_async_max
+= n
;
1558 pbuf_adjcount(&nsw_wcount_async
, n
);
1560 lwkt_reltoken(&vm_token
);
1566 * Assign swap blocks and issue I/O. We reallocate swap on the fly.
1567 * The page is left dirty until the pageout operation completes
1571 for (i
= 0; i
< count
; i
+= n
) {
1578 * Maximum I/O size is limited by a number of factors.
1581 n
= min(BLIST_MAX_ALLOC
, count
- i
);
1582 n
= min(n
, nsw_cluster_max
);
1584 lwkt_gettoken(&vm_token
);
1587 * Get biggest block of swap we can. If we fail, fall
1588 * back and try to allocate a smaller block. Don't go
1589 * overboard trying to allocate space if it would overly
1593 (blk
= swp_pager_getswapspace(object
, n
)) == SWAPBLK_NONE
&&
1598 if (blk
== SWAPBLK_NONE
) {
1599 for (j
= 0; j
< n
; ++j
)
1600 rtvals
[i
+j
] = VM_PAGER_FAIL
;
1601 lwkt_reltoken(&vm_token
);
1604 if (vm_report_swap_allocs
> 0) {
1605 kprintf("swap_alloc %08jx,%d\n", (intmax_t)blk
, n
);
1606 --vm_report_swap_allocs
;
1610 * The I/O we are constructing cannot cross a physical
1611 * disk boundry in the swap stripe.
1613 if ((blk
^ (blk
+ n
)) & ~SWB_DMMASK
) {
1614 j
= ((blk
+ SWB_DMMAX
) & ~SWB_DMMASK
) - blk
;
1615 swp_pager_freeswapspace(object
, blk
+ j
, n
- j
);
1620 * All I/O parameters have been satisfied, build the I/O
1621 * request and assign the swap space.
1623 if ((flags
& VM_PAGER_PUT_SYNC
))
1624 bp
= getpbuf_kva(&nsw_wcount_sync
);
1626 bp
= getpbuf_kva(&nsw_wcount_async
);
1629 lwkt_reltoken(&vm_token
);
1631 pmap_qenter((vm_offset_t
)bp
->b_data
, &m
[i
], n
);
1633 bp
->b_bcount
= PAGE_SIZE
* n
;
1634 bio
->bio_offset
= (off_t
)blk
<< PAGE_SHIFT
;
1636 for (j
= 0; j
< n
; ++j
) {
1637 vm_page_t mreq
= m
[i
+j
];
1639 swp_pager_meta_build(mreq
->object
, mreq
->pindex
,
1641 if (object
->type
== OBJT_SWAP
)
1642 vm_page_dirty(mreq
);
1643 rtvals
[i
+j
] = VM_PAGER_OK
;
1645 vm_page_flag_set(mreq
, PG_SWAPINPROG
);
1646 bp
->b_xio
.xio_pages
[j
] = mreq
;
1648 bp
->b_xio
.xio_npages
= n
;
1650 mycpu
->gd_cnt
.v_swapout
++;
1651 mycpu
->gd_cnt
.v_swappgsout
+= bp
->b_xio
.xio_npages
;
1653 bp
->b_dirtyoff
= 0; /* req'd for NFS */
1654 bp
->b_dirtyend
= bp
->b_bcount
; /* req'd for NFS */
1655 bp
->b_cmd
= BUF_CMD_WRITE
;
1656 bio
->bio_caller_info1
.index
= SWBIO_WRITE
;
1659 /* PMAP TESTING CODE (useful, keep it in but #if 0'd) */
1660 bio
->bio_crc
= iscsi_crc32(bp
->b_data
, bp
->b_bcount
);
1663 for (j
= 0; j
< n
; ++j
) {
1664 vm_page_t mm
= bp
->b_xio
.xio_pages
[j
];
1665 char *p
= (char *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(mm
));
1666 crc
= iscsi_crc32_ext(p
, PAGE_SIZE
, crc
);
1668 if (bio
->bio_crc
!= crc
) {
1669 kprintf("PREWRITE MISMATCH-A "
1670 "bdata=%08x dmap=%08x bdata=%08x (%d)\n",
1673 iscsi_crc32(bp
->b_data
, bp
->b_bcount
),
1675 #ifdef _KERNEL_VIRTUAL
1676 madvise(bp
->b_data
, bp
->b_bcount
, MADV_INVAL
);
1679 for (j
= 0; j
< n
; ++j
) {
1680 vm_page_t mm
= bp
->b_xio
.xio_pages
[j
];
1681 char *p
= (char *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(mm
));
1682 crc
= iscsi_crc32_ext(p
, PAGE_SIZE
, crc
);
1684 kprintf("PREWRITE MISMATCH-B "
1685 "bdata=%08x dmap=%08x\n",
1686 iscsi_crc32(bp
->b_data
, bp
->b_bcount
),
1695 if ((flags
& VM_PAGER_PUT_SYNC
) == 0) {
1696 bio
->bio_done
= swp_pager_async_iodone
;
1698 vn_strategy(swapdev_vp
, bio
);
1700 for (j
= 0; j
< n
; ++j
)
1701 rtvals
[i
+j
] = VM_PAGER_PEND
;
1706 * Issue synchrnously.
1708 * Wait for the sync I/O to complete, then update rtvals.
1709 * We just set the rtvals[] to VM_PAGER_PEND so we can call
1710 * our async completion routine at the end, thus avoiding a
1713 bio
->bio_caller_info1
.index
|= SWBIO_SYNC
;
1714 if (flags
& VM_PAGER_TRY_TO_CACHE
)
1715 bio
->bio_caller_info1
.index
|= SWBIO_TTC
;
1716 bio
->bio_done
= biodone_sync
;
1717 bio
->bio_flags
|= BIO_SYNC
;
1718 vn_strategy(swapdev_vp
, bio
);
1719 biowait(bio
, "swwrt");
1721 for (j
= 0; j
< n
; ++j
)
1722 rtvals
[i
+j
] = VM_PAGER_PEND
;
1725 * Now that we are through with the bp, we can call the
1726 * normal async completion, which frees everything up.
1728 swp_pager_async_iodone(bio
);
1730 vm_object_drop(object
);
1736 * Recalculate the low and high-water marks.
1739 swap_pager_newswap(void)
1742 * NOTE: vm_swap_max cannot exceed 1 billion blocks, which is the
1743 * limitation imposed by the blist code. Remember that this
1744 * will be divided by NSWAP_MAX (4), so each swap device is
1745 * limited to around a terrabyte.
1748 nswap_lowat
= (int64_t)vm_swap_max
* 4 / 100; /* 4% left */
1749 nswap_hiwat
= (int64_t)vm_swap_max
* 6 / 100; /* 6% left */
1750 kprintf("swap low/high-water marks set to %d/%d\n",
1751 nswap_lowat
, nswap_hiwat
);
1760 * swp_pager_async_iodone:
1762 * Completion routine for asynchronous reads and writes from/to swap.
1763 * Also called manually by synchronous code to finish up a bp.
1765 * For READ operations, the pages are PG_BUSY'd. For WRITE operations,
1766 * the pages are vm_page_t->busy'd. For READ operations, we PG_BUSY
1767 * unbusy all pages except the 'main' request page. For WRITE
1768 * operations, we vm_page_t->busy'd unbusy all pages ( we can do this
1769 * because we marked them all VM_PAGER_PEND on return from putpages ).
1771 * This routine may not block.
1776 swp_pager_async_iodone(struct bio
*bio
)
1778 struct buf
*bp
= bio
->bio_buf
;
1779 vm_object_t object
= NULL
;
1786 if (bp
->b_flags
& B_ERROR
) {
1788 "swap_pager: I/O error - %s failed; offset %lld,"
1789 "size %ld, error %d\n",
1790 ((bio
->bio_caller_info1
.index
& SWBIO_READ
) ?
1791 "pagein" : "pageout"),
1792 (long long)bio
->bio_offset
,
1801 if (bp
->b_xio
.xio_npages
)
1802 object
= bp
->b_xio
.xio_pages
[0]->object
;
1805 /* PMAP TESTING CODE (useful, keep it in but #if 0'd) */
1806 if (bio
->bio_caller_info1
.index
& SWBIO_WRITE
) {
1807 if (bio
->bio_crc
!= iscsi_crc32(bp
->b_data
, bp
->b_bcount
)) {
1808 kprintf("SWAPOUT: BADCRC %08x %08x\n",
1810 iscsi_crc32(bp
->b_data
, bp
->b_bcount
));
1811 for (i
= 0; i
< bp
->b_xio
.xio_npages
; ++i
) {
1812 vm_page_t m
= bp
->b_xio
.xio_pages
[i
];
1813 if (m
->flags
& PG_WRITEABLE
)
1815 "%d/%d %p writable\n",
1816 i
, bp
->b_xio
.xio_npages
, m
);
1823 * remove the mapping for kernel virtual
1825 pmap_qremove((vm_offset_t
)bp
->b_data
, bp
->b_xio
.xio_npages
);
1828 * cleanup pages. If an error occurs writing to swap, we are in
1829 * very serious trouble. If it happens to be a disk error, though,
1830 * we may be able to recover by reassigning the swap later on. So
1831 * in this case we remove the m->swapblk assignment for the page
1832 * but do not free it in the rlist. The errornous block(s) are thus
1833 * never reallocated as swap. Redirty the page and continue.
1835 for (i
= 0; i
< bp
->b_xio
.xio_npages
; ++i
) {
1836 vm_page_t m
= bp
->b_xio
.xio_pages
[i
];
1838 if (bp
->b_flags
& B_ERROR
) {
1840 * If an error occurs I'd love to throw the swapblk
1841 * away without freeing it back to swapspace, so it
1842 * can never be used again. But I can't from an
1846 if (bio
->bio_caller_info1
.index
& SWBIO_READ
) {
1848 * When reading, reqpage needs to stay
1849 * locked for the parent, but all other
1850 * pages can be freed. We still want to
1851 * wakeup the parent waiting on the page,
1852 * though. ( also: pg_reqpage can be -1 and
1853 * not match anything ).
1855 * We have to wake specifically requested pages
1856 * up too because we cleared PG_SWAPINPROG and
1857 * someone may be waiting for that.
1859 * NOTE: For reads, m->dirty will probably
1860 * be overridden by the original caller
1861 * of getpages so don't play cute tricks
1864 * NOTE: We can't actually free the page from
1865 * here, because this is an interrupt.
1866 * It is not legal to mess with
1867 * object->memq from an interrupt.
1868 * Deactivate the page instead.
1870 * WARNING! The instant PG_SWAPINPROG is
1871 * cleared another cpu may start
1872 * using the mreq page (it will
1873 * check m->valid immediately).
1877 vm_page_flag_clear(m
, PG_SWAPINPROG
);
1880 * bio_driver_info holds the requested page
1883 if (i
!= (int)(intptr_t)bio
->bio_driver_info
) {
1884 vm_page_deactivate(m
);
1890 * If i == bp->b_pager.pg_reqpage, do not wake
1891 * the page up. The caller needs to.
1895 * If a write error occurs remove the swap
1896 * assignment (note that PG_SWAPPED may or
1897 * may not be set depending on prior activity).
1899 * Re-dirty OBJT_SWAP pages as there is no
1900 * other backing store, we can't throw the
1903 * Non-OBJT_SWAP pages (aka swapcache) must
1904 * not be dirtied since they may not have
1905 * been dirty in the first place, and they
1906 * do have backing store (the vnode).
1908 vm_page_busy_wait(m
, FALSE
, "swadpg");
1909 vm_object_hold(m
->object
);
1910 swp_pager_meta_ctl(m
->object
, m
->pindex
,
1912 vm_page_flag_clear(m
, PG_SWAPPED
);
1913 vm_object_drop(m
->object
);
1914 if (m
->object
->type
== OBJT_SWAP
) {
1916 vm_page_activate(m
);
1918 vm_page_io_finish(m
);
1919 vm_page_flag_clear(m
, PG_SWAPINPROG
);
1922 } else if (bio
->bio_caller_info1
.index
& SWBIO_READ
) {
1924 * NOTE: for reads, m->dirty will probably be
1925 * overridden by the original caller of getpages so
1926 * we cannot set them in order to free the underlying
1927 * swap in a low-swap situation. I don't think we'd
1928 * want to do that anyway, but it was an optimization
1929 * that existed in the old swapper for a time before
1930 * it got ripped out due to precisely this problem.
1932 * If not the requested page then deactivate it.
1934 * Note that the requested page, reqpage, is left
1935 * busied, but we still have to wake it up. The
1936 * other pages are released (unbusied) by
1937 * vm_page_wakeup(). We do not set reqpage's
1938 * valid bits here, it is up to the caller.
1942 * NOTE: Can't call pmap_clear_modify(m) from an
1943 * interrupt thread, the pmap code may have to
1944 * map non-kernel pmaps and currently asserts
1947 * WARNING! The instant PG_SWAPINPROG is
1948 * cleared another cpu may start
1949 * using the mreq page (it will
1950 * check m->valid immediately).
1952 /*pmap_clear_modify(m);*/
1953 m
->valid
= VM_PAGE_BITS_ALL
;
1955 vm_page_flag_set(m
, PG_SWAPPED
);
1956 vm_page_flag_clear(m
, PG_SWAPINPROG
);
1959 * We have to wake specifically requested pages
1960 * up too because we cleared PG_SWAPINPROG and
1961 * could be waiting for it in getpages. However,
1962 * be sure to not unbusy getpages specifically
1963 * requested page - getpages expects it to be
1966 * bio_driver_info holds the requested page
1968 if (i
!= (int)(intptr_t)bio
->bio_driver_info
) {
1969 vm_page_deactivate(m
);
1976 * Mark the page clean but do not mess with the
1977 * pmap-layer's modified state. That state should
1978 * also be clear since the caller protected the
1979 * page VM_PROT_READ, but allow the case.
1981 * We are in an interrupt, avoid pmap operations.
1983 * If we have a severe page deficit, deactivate the
1984 * page. Do not try to cache it (which would also
1985 * involve a pmap op), because the page might still
1988 * When using the swap to cache clean vnode pages
1989 * we do not mess with the page dirty bits.
1991 * NOTE! Nobody is waiting for the key mreq page
1992 * on write completion.
1994 vm_page_busy_wait(m
, FALSE
, "swadpg");
1995 if (m
->object
->type
== OBJT_SWAP
)
1997 vm_page_flag_set(m
, PG_SWAPPED
);
1998 vm_page_flag_clear(m
, PG_SWAPINPROG
);
1999 if (vm_page_count_severe())
2000 vm_page_deactivate(m
);
2001 vm_page_io_finish(m
);
2002 if (bio
->bio_caller_info1
.index
& SWBIO_TTC
)
2003 vm_page_try_to_cache(m
);
2010 * adjust pip. NOTE: the original parent may still have its own
2011 * pip refs on the object.
2015 vm_object_pip_wakeup_n(object
, bp
->b_xio
.xio_npages
);
2018 * Release the physical I/O buffer.
2020 * NOTE: Due to synchronous operations in the write case b_cmd may
2021 * already be set to BUF_CMD_DONE and BIO_SYNC may have already
2024 * Use vm_token to interlock nsw_rcount/wcount wakeup?
2026 lwkt_gettoken(&vm_token
);
2027 if (bio
->bio_caller_info1
.index
& SWBIO_READ
)
2028 nswptr
= &nsw_rcount
;
2029 else if (bio
->bio_caller_info1
.index
& SWBIO_SYNC
)
2030 nswptr
= &nsw_wcount_sync
;
2032 nswptr
= &nsw_wcount_async
;
2033 bp
->b_cmd
= BUF_CMD_DONE
;
2034 relpbuf(bp
, nswptr
);
2035 lwkt_reltoken(&vm_token
);
2039 * Fault-in a potentially swapped page and remove the swap reference.
2040 * (used by swapoff code)
2042 * object must be held.
2044 static __inline
void
2045 swp_pager_fault_page(vm_object_t object
, int *sharedp
, vm_pindex_t pindex
)
2051 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
2053 if (object
->type
== OBJT_VNODE
) {
2055 * Any swap related to a vnode is due to swapcache. We must
2056 * vget() the vnode in case it is not active (otherwise
2057 * vref() will panic). Calling vm_object_page_remove() will
2058 * ensure that any swap ref is removed interlocked with the
2059 * page. clean_only is set to TRUE so we don't throw away
2062 vp
= object
->handle
;
2063 error
= vget(vp
, LK_SHARED
| LK_RETRY
| LK_CANRECURSE
);
2065 vm_object_page_remove(object
, pindex
, pindex
+ 1, TRUE
);
2070 * Otherwise it is a normal OBJT_SWAP object and we can
2071 * fault the page in and remove the swap.
2073 m
= vm_fault_object_page(object
, IDX_TO_OFF(pindex
),
2075 VM_FAULT_DIRTY
| VM_FAULT_UNSWAP
,
2083 * This removes all swap blocks related to a particular device. We have
2084 * to be careful of ripups during the scan.
2086 static int swp_pager_swapoff_callback(struct swblock
*swap
, void *data
);
2089 swap_pager_swapoff(int devidx
)
2091 struct vm_object_hash
*hash
;
2092 struct swswapoffinfo info
;
2093 struct vm_object marker
;
2097 bzero(&marker
, sizeof(marker
));
2098 marker
.type
= OBJT_MARKER
;
2100 for (n
= 0; n
< VMOBJ_HSIZE
; ++n
) {
2101 hash
= &vm_object_hash
[n
];
2103 lwkt_gettoken(&hash
->token
);
2104 TAILQ_INSERT_HEAD(&hash
->list
, &marker
, object_list
);
2106 while ((object
= TAILQ_NEXT(&marker
, object_list
)) != NULL
) {
2107 if (object
->type
== OBJT_MARKER
)
2109 if (object
->type
!= OBJT_SWAP
&&
2110 object
->type
!= OBJT_VNODE
)
2112 vm_object_hold(object
);
2113 if (object
->type
!= OBJT_SWAP
&&
2114 object
->type
!= OBJT_VNODE
) {
2115 vm_object_drop(object
);
2118 info
.object
= object
;
2120 info
.devidx
= devidx
;
2121 swblock_rb_tree_RB_SCAN(&object
->swblock_root
,
2122 NULL
, swp_pager_swapoff_callback
,
2124 vm_object_drop(object
);
2126 if (object
== TAILQ_NEXT(&marker
, object_list
)) {
2127 TAILQ_REMOVE(&hash
->list
, &marker
, object_list
);
2128 TAILQ_INSERT_AFTER(&hash
->list
, object
,
2129 &marker
, object_list
);
2132 TAILQ_REMOVE(&hash
->list
, &marker
, object_list
);
2133 lwkt_reltoken(&hash
->token
);
2137 * If we fail to locate all swblocks we just fail gracefully and
2138 * do not bother to restore paging on the swap device. If the
2139 * user wants to retry the user can retry.
2141 if (swdevt
[devidx
].sw_nused
)
2149 swp_pager_swapoff_callback(struct swblock
*swap
, void *data
)
2151 struct swswapoffinfo
*info
= data
;
2152 vm_object_t object
= info
->object
;
2157 index
= swap
->swb_index
;
2158 for (i
= 0; i
< SWAP_META_PAGES
; ++i
) {
2160 * Make sure we don't race a dying object. This will
2161 * kill the scan of the object's swap blocks entirely.
2163 if (object
->flags
& OBJ_DEAD
)
2167 * Fault the page, which can obviously block. If the swap
2168 * structure disappears break out.
2170 v
= swap
->swb_pages
[i
];
2171 if (v
!= SWAPBLK_NONE
&& BLK2DEVIDX(v
) == info
->devidx
) {
2172 swp_pager_fault_page(object
, &info
->shared
,
2173 swap
->swb_index
+ i
);
2174 /* swap ptr might go away */
2175 if (RB_LOOKUP(swblock_rb_tree
,
2176 &object
->swblock_root
, index
) != swap
) {
2184 /************************************************************************
2186 ************************************************************************
2188 * These routines manipulate the swap metadata stored in the
2191 * Swap metadata is implemented with a global hash and not directly
2192 * linked into the object. Instead the object simply contains
2193 * appropriate tracking counters.
2197 * Lookup the swblock containing the specified swap block index.
2199 * The caller must hold the object.
2203 swp_pager_lookup(vm_object_t object
, vm_pindex_t index
)
2205 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
2206 index
&= ~(vm_pindex_t
)SWAP_META_MASK
;
2207 return (RB_LOOKUP(swblock_rb_tree
, &object
->swblock_root
, index
));
2211 * Remove a swblock from the RB tree.
2213 * The caller must hold the object.
2217 swp_pager_remove(vm_object_t object
, struct swblock
*swap
)
2219 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
2220 RB_REMOVE(swblock_rb_tree
, &object
->swblock_root
, swap
);
2224 * Convert default object to swap object if necessary
2226 * The caller must hold the object.
2229 swp_pager_meta_convert(vm_object_t object
)
2231 if (object
->type
== OBJT_DEFAULT
) {
2232 object
->type
= OBJT_SWAP
;
2233 KKASSERT(object
->swblock_count
== 0);
2238 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object
2240 * We first convert the object to a swap object if it is a default
2241 * object. Vnode objects do not need to be converted.
2243 * The specified swapblk is added to the object's swap metadata. If
2244 * the swapblk is not valid, it is freed instead. Any previously
2245 * assigned swapblk is freed.
2247 * The caller must hold the object.
2250 swp_pager_meta_build(vm_object_t object
, vm_pindex_t index
, swblk_t swapblk
)
2252 struct swblock
*swap
;
2253 struct swblock
*oswap
;
2256 KKASSERT(swapblk
!= SWAPBLK_NONE
);
2257 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
2260 * Convert object if necessary
2262 if (object
->type
== OBJT_DEFAULT
)
2263 swp_pager_meta_convert(object
);
2266 * Locate swblock. If not found create, but if we aren't adding
2267 * anything just return. If we run out of space in the map we wait
2268 * and, since the hash table may have changed, retry.
2271 swap
= swp_pager_lookup(object
, index
);
2276 swap
= zalloc(swap_zone
);
2281 swap
->swb_index
= index
& ~(vm_pindex_t
)SWAP_META_MASK
;
2282 swap
->swb_count
= 0;
2284 ++object
->swblock_count
;
2286 for (i
= 0; i
< SWAP_META_PAGES
; ++i
)
2287 swap
->swb_pages
[i
] = SWAPBLK_NONE
;
2288 oswap
= RB_INSERT(swblock_rb_tree
, &object
->swblock_root
, swap
);
2289 KKASSERT(oswap
== NULL
);
2293 * Delete prior contents of metadata.
2295 * NOTE: Decrement swb_count after the freeing operation (which
2296 * might block) to prevent racing destruction of the swblock.
2298 index
&= SWAP_META_MASK
;
2300 while ((v
= swap
->swb_pages
[index
]) != SWAPBLK_NONE
) {
2301 swap
->swb_pages
[index
] = SWAPBLK_NONE
;
2303 swp_pager_freeswapspace(object
, v
, 1);
2305 --mycpu
->gd_vmtotal
.t_vm
;
2309 * Enter block into metadata
2311 swap
->swb_pages
[index
] = swapblk
;
2312 if (swapblk
!= SWAPBLK_NONE
) {
2314 ++mycpu
->gd_vmtotal
.t_vm
;
2319 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata
2321 * The requested range of blocks is freed, with any associated swap
2322 * returned to the swap bitmap.
2324 * This routine will free swap metadata structures as they are cleaned
2325 * out. This routine does *NOT* operate on swap metadata associated
2326 * with resident pages.
2328 * The caller must hold the object.
2330 static int swp_pager_meta_free_callback(struct swblock
*swb
, void *data
);
2333 swp_pager_meta_free(vm_object_t object
, vm_pindex_t index
, vm_pindex_t count
)
2335 struct swfreeinfo info
;
2337 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
2342 if (object
->swblock_count
== 0) {
2343 KKASSERT(RB_EMPTY(&object
->swblock_root
));
2350 * Setup for RB tree scan. Note that the pindex range can be huge
2351 * due to the 64 bit page index space so we cannot safely iterate.
2353 info
.object
= object
;
2354 info
.basei
= index
& ~(vm_pindex_t
)SWAP_META_MASK
;
2356 info
.endi
= index
+ count
- 1;
2357 swblock_rb_tree_RB_SCAN(&object
->swblock_root
, rb_swblock_scancmp
,
2358 swp_pager_meta_free_callback
, &info
);
2362 * The caller must hold the object.
2366 swp_pager_meta_free_callback(struct swblock
*swap
, void *data
)
2368 struct swfreeinfo
*info
= data
;
2369 vm_object_t object
= info
->object
;
2374 * Figure out the range within the swblock. The wider scan may
2375 * return edge-case swap blocks when the start and/or end points
2376 * are in the middle of a block.
2378 if (swap
->swb_index
< info
->begi
)
2379 index
= (int)info
->begi
& SWAP_META_MASK
;
2383 if (swap
->swb_index
+ SWAP_META_PAGES
> info
->endi
)
2384 eindex
= (int)info
->endi
& SWAP_META_MASK
;
2386 eindex
= SWAP_META_MASK
;
2389 * Scan and free the blocks. The loop terminates early
2390 * if (swap) runs out of blocks and could be freed.
2392 * NOTE: Decrement swb_count after swp_pager_freeswapspace()
2393 * to deal with a zfree race.
2395 while (index
<= eindex
) {
2396 swblk_t v
= swap
->swb_pages
[index
];
2398 if (v
!= SWAPBLK_NONE
) {
2399 swap
->swb_pages
[index
] = SWAPBLK_NONE
;
2401 swp_pager_freeswapspace(object
, v
, 1);
2402 --mycpu
->gd_vmtotal
.t_vm
;
2403 if (--swap
->swb_count
== 0) {
2404 swp_pager_remove(object
, swap
);
2405 zfree(swap_zone
, swap
);
2406 --object
->swblock_count
;
2413 /* swap may be invalid here due to zfree above */
2420 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object
2422 * This routine locates and destroys all swap metadata associated with
2425 * NOTE: Decrement swb_count after the freeing operation (which
2426 * might block) to prevent racing destruction of the swblock.
2428 * The caller must hold the object.
2431 swp_pager_meta_free_all(vm_object_t object
)
2433 struct swblock
*swap
;
2436 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object
));
2438 while ((swap
= RB_ROOT(&object
->swblock_root
)) != NULL
) {
2439 swp_pager_remove(object
, swap
);
2440 for (i
= 0; i
< SWAP_META_PAGES
; ++i
) {
2441 swblk_t v
= swap
->swb_pages
[i
];
2442 if (v
!= SWAPBLK_NONE
) {
2444 swp_pager_freeswapspace(object
, v
, 1);
2446 --mycpu
->gd_vmtotal
.t_vm
;
2449 if (swap
->swb_count
!= 0)
2450 panic("swap_pager_meta_free_all: swb_count != 0");
2451 zfree(swap_zone
, swap
);
2452 --object
->swblock_count
;
2455 KKASSERT(object
->swblock_count
== 0);
2459 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data.
2461 * This routine is capable of looking up, popping, or freeing
2462 * swapblk assignments in the swap meta data or in the vm_page_t.
2463 * The routine typically returns the swapblk being looked-up, or popped,
2464 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block
2465 * was invalid. This routine will automatically free any invalid
2466 * meta-data swapblks.
2468 * It is not possible to store invalid swapblks in the swap meta data
2469 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking.
2471 * When acting on a busy resident page and paging is in progress, we
2472 * have to wait until paging is complete but otherwise can act on the
2475 * SWM_FREE remove and free swap block from metadata
2476 * SWM_POP remove from meta data but do not free.. pop it out
2478 * The caller must hold the object.
2481 swp_pager_meta_ctl(vm_object_t object
, vm_pindex_t index
, int flags
)
2483 struct swblock
*swap
;
2486 if (object
->swblock_count
== 0)
2487 return(SWAPBLK_NONE
);
2490 swap
= swp_pager_lookup(object
, index
);
2493 index
&= SWAP_META_MASK
;
2494 r1
= swap
->swb_pages
[index
];
2496 if (r1
!= SWAPBLK_NONE
) {
2497 if (flags
& (SWM_FREE
|SWM_POP
)) {
2498 swap
->swb_pages
[index
] = SWAPBLK_NONE
;
2499 --mycpu
->gd_vmtotal
.t_vm
;
2500 if (--swap
->swb_count
== 0) {
2501 swp_pager_remove(object
, swap
);
2502 zfree(swap_zone
, swap
);
2503 --object
->swblock_count
;
2506 /* swap ptr may be invalid */
2507 if (flags
& SWM_FREE
) {
2508 swp_pager_freeswapspace(object
, r1
, 1);
2512 /* swap ptr may be invalid */