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31 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94
32 * $FreeBSD: src/sys/vm/vm_swap.c,v 1.96.2.2 2001/10/14 18:46:47 iedowse Exp $
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/sysproto.h>
43 #include <sys/nlookup.h>
44 #include <sys/sysctl.h>
45 #include <sys/dmap.h> /* XXX */
46 #include <sys/vnode.h>
47 #include <sys/fcntl.h>
48 #include <sys/blist.h>
49 #include <sys/kernel.h>
55 #include <vm/vm_extern.h>
56 #include <vm/swap_pager.h>
57 #include <vm/vm_zone.h>
58 #include <vm/vm_param.h>
60 #include <sys/thread2.h>
61 #include <sys/mutex2.h>
62 #include <sys/spinlock2.h>
65 * Indirect driver for multi-controller paging.
71 static struct swdevt should_be_malloced[NSWAPDEV];
72 struct swdevt *swdevt = should_be_malloced; /* exported to pstat/systat */
73 static swblk_t nswap; /* first block after the interleaved devs */
74 static struct mtx swap_mtx = MTX_INITIALIZER("swpmtx");
75 int nswdev = NSWAPDEV; /* exported to pstat/systat */
79 static int swapoff_one(int index);
80 struct vnode *swapdev_vp;
83 * (struct vnode *a_vp, struct bio *b_bio)
85 * vn_strategy() for swapdev_vp. Perform swap strategy interleave device
91 swapdev_strategy(struct vop_strategy_args *ap)
93 struct bio *bio = ap->a_bio;
95 struct buf *bp = bio->bio_buf;
96 swblk_t sz, off, seg, blkno, nblkno;
99 sz = howmany(bp->b_bcount, PAGE_SIZE);
100 blkno = (swblk_t)(bio->bio_offset >> PAGE_SHIFT);
103 * Convert interleaved swap into per-device swap. Note that
104 * the block size is left in PAGE_SIZE'd chunks (for the newswap)
107 nbio = push_bio(bio);
109 off = blkno % SWB_DMMAX;
110 if (off + sz > SWB_DMMAX) {
111 bp->b_error = EINVAL;
112 bp->b_flags |= B_ERROR;
116 seg = blkno / SWB_DMMAX;
117 index = seg % nswdev;
119 nbio->bio_offset = (off_t)(seg * SWB_DMMAX + off) << PAGE_SHIFT;
122 nbio->bio_offset = bio->bio_offset;
124 nblkno = (swblk_t)(nbio->bio_offset >> PAGE_SHIFT);
126 if (nblkno + sz > sp->sw_nblks) {
127 bp->b_error = EINVAL;
128 bp->b_flags |= B_ERROR;
129 /* I/O was never started on nbio, must biodone(bio) */
133 if (sp->sw_vp == NULL) {
134 bp->b_error = ENODEV;
135 bp->b_flags |= B_ERROR;
136 /* I/O was never started on nbio, must biodone(bio) */
142 * Issue a strategy call on the appropriate swap vnode. Note that
143 * bp->b_vp is not modified. Strategy code is always supposed to
146 * We have to use vn_strategy() here even if we know we have a
147 * device in order to properly break up requests which exceed the
148 * device's DMA limits.
150 vn_strategy(sp->sw_vp, nbio);
155 swapdev_inactive(struct vop_inactive_args *ap)
162 swapdev_reclaim(struct vop_reclaim_args *ap)
168 * Create a special vnode op vector for swapdev_vp - we only use
169 * vn_strategy(), everything else returns an error.
171 static struct vop_ops swapdev_vnode_vops = {
172 .vop_default = vop_defaultop,
173 .vop_strategy = swapdev_strategy,
174 .vop_inactive = swapdev_inactive,
175 .vop_reclaim = swapdev_reclaim
177 static struct vop_ops *swapdev_vnode_vops_p = &swapdev_vnode_vops;
179 VNODEOP_SET(swapdev_vnode_vops);
182 * swapon_args(char *name)
184 * System call swapon(name) enables swapping on device name,
185 * which must be in the swdevsw. Return EBUSY
186 * if already swapping on this device.
191 sys_swapon(struct swapon_args *uap)
193 struct thread *td = curthread;
196 struct nlookupdata nd;
199 error = priv_check(td, PRIV_ROOT);
205 error = nlookup_init(&nd, uap->name, UIO_USERSPACE, NLC_FOLLOW);
207 error = nlookup(&nd);
209 error = cache_vref(&nd.nl_nch, nd.nl_cred, &vp);
212 mtx_unlock(&swap_mtx);
216 if (vn_isdisk(vp, &error)) {
217 error = swaponvp(td, vp, 0);
218 } else if (vp->v_type == VREG && vp->v_tag == VT_NFS &&
219 (error = VOP_GETATTR(vp, &attr)) == 0) {
221 * Allow direct swapping to NFS regular files in the same
222 * way that nfs_mountroot() sets up diskless swapping.
224 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE);
228 mtx_unlock(&swap_mtx);
234 * Swfree(index) frees the index'th portion of the swap map.
235 * Each of the nswdev devices provides 1/nswdev'th of the swap
236 * space, which is laid out with blocks of SWB_DMMAX pages circularly
239 * The new swap code uses page-sized blocks. The old swap code used
240 * DEV_BSIZE'd chunks.
242 * XXX locking when multiple swapon's run in parallel
245 swaponvp(struct thread *td, struct vnode *vp, u_quad_t nblks)
247 swblk_t aligned_nblks;
260 lwkt_gettoken(&vm_token); /* needed for vm_swap_size and blist */
264 error = getspecialvnode(VT_NON, NULL, &swapdev_vnode_vops_p,
267 panic("Cannot get vnode for swapdev");
268 swapdev_vp->v_type = VNON; /* Untyped */
269 vx_unlock(swapdev_vp);
272 for (sp = swdevt, index = 0 ; index < nswdev; index++, sp++) {
273 if (sp->sw_vp == vp) {
284 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
285 error = VOP_OPEN(vp, FREAD | FWRITE, cred, NULL);
291 * v_rdev is not valid until after the VOP_OPEN() call. dev_psize()
292 * must be supported if a character device has been specified.
294 if (vp->v_type == VCHR)
299 if (nblks == 0 && dev != NULL) {
300 dpsize = dev_dpsize(dev);
302 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
303 VOP_CLOSE(vp, FREAD | FWRITE, NULL);
308 nblks = (u_quad_t)dpsize;
311 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
312 VOP_CLOSE(vp, FREAD | FWRITE, NULL);
319 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
320 * First chop nblks off to page-align it, then convert.
322 * sw->sw_nblks is in page-sized chunks now too.
324 nblks &= ~(u_quad_t)(ctodb(1) - 1);
325 nblks = dbtoc(nblks);
328 * Post-conversion nblks must not be >= BLIST_MAXBLKS, and
329 * we impose a 4-swap-device limit so we have to divide it out
330 * further. Going beyond this will result in overflows in the
333 * Post-conversion nblks must fit within a (swblk_t), which
334 * this test also ensures.
336 if (nblks > BLIST_MAXBLKS / nswdev) {
337 kprintf("exceeded maximum of %ld blocks per swap unit\n",
338 (long)BLIST_MAXBLKS / nswdev);
339 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
340 VOP_CLOSE(vp, FREAD | FWRITE, NULL);
347 sp->sw_dev = dev2udev(dev);
349 sp->sw_flags = SW_FREED;
353 * nblks, nswap, and SWB_DMMAX are PAGE_SIZE'd parameters now, not
354 * DEV_BSIZE'd. aligned_nblks is used to calculate the
355 * size of the swap bitmap, taking into account the stripe size.
357 aligned_nblks = (swblk_t)((nblks + SWB_DMMASK) &
358 ~(u_swblk_t)SWB_DMMASK);
359 sp->sw_nblks = aligned_nblks;
361 if (aligned_nblks * nswdev > nswap)
362 nswap = aligned_nblks * nswdev;
364 if (swapblist == NULL)
365 swapblist = blist_create(nswap);
367 blist_resize(&swapblist, nswap, 0);
369 for (dvbase = SWB_DMMAX; dvbase < aligned_nblks; dvbase += SWB_DMMAX) {
370 blk = min(aligned_nblks - dvbase, SWB_DMMAX);
371 vsbase = index * SWB_DMMAX + dvbase * nswdev;
372 blist_free(swapblist, vsbase, blk);
376 swap_pager_newswap();
379 mtx_unlock(&swap_mtx);
380 lwkt_reltoken(&vm_token);
385 * swapoff_args(char *name)
387 * System call swapoff(name) disables swapping on device name,
388 * which must be an active swap device. Return ENOMEM
389 * if there is not enough memory to page in the contents of
395 sys_swapoff(struct swapoff_args *uap)
398 struct nlookupdata nd;
402 error = priv_check(curthread, PRIV_ROOT);
408 error = nlookup_init(&nd, uap->name, UIO_USERSPACE, NLC_FOLLOW);
410 error = nlookup(&nd);
412 error = cache_vref(&nd.nl_nch, nd.nl_cred, &vp);
417 for (sp = swdevt, index = 0; index < nswdev; index++, sp++) {
424 error = swapoff_one(index);
425 swap_pager_newswap();
428 mtx_unlock(&swap_mtx);
433 swapoff_one(int index)
435 swblk_t blk, aligned_nblks;
436 swblk_t dvbase, vsbase;
437 u_int pq_active_clean, pq_inactive_clean;
439 struct vm_page marker;
446 aligned_nblks = sp->sw_nblks;
447 pq_active_clean = pq_inactive_clean = 0;
450 * We can turn off this swap device safely only if the
451 * available virtual memory in the system will fit the amount
452 * of data we will have to page back in, plus an epsilon so
453 * the system doesn't become critically low on swap space.
455 for (q = 0; q < PQ_L2_SIZE; ++q) {
456 bzero(&marker, sizeof(marker));
457 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER;
458 marker.queue = PQ_ACTIVE + q;
460 marker.wire_count = 1;
462 vm_page_queues_spin_lock(marker.queue);
463 TAILQ_INSERT_HEAD(&vm_page_queues[marker.queue].pl,
466 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL) {
467 TAILQ_REMOVE(&vm_page_queues[marker.queue].pl,
469 TAILQ_INSERT_AFTER(&vm_page_queues[marker.queue].pl, m,
471 if (m->flags & (PG_MARKER | PG_FICTITIOUS))
474 if (vm_page_busy_try(m, FALSE) == 0) {
475 vm_page_queues_spin_unlock(marker.queue);
477 vm_page_test_dirty(m);
482 vm_page_queues_spin_lock(marker.queue);
485 TAILQ_REMOVE(&vm_page_queues[marker.queue].pl, &marker, pageq);
486 vm_page_queues_spin_unlock(marker.queue);
488 marker.queue = PQ_INACTIVE + q;
490 vm_page_queues_spin_lock(marker.queue);
491 TAILQ_INSERT_HEAD(&vm_page_queues[marker.queue].pl,
494 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL) {
496 &vm_page_queues[marker.queue].pl,
499 &vm_page_queues[marker.queue].pl,
501 if (m->flags & (PG_MARKER | PG_FICTITIOUS))
504 if (vm_page_busy_try(m, FALSE) == 0) {
505 vm_page_queues_spin_unlock(marker.queue);
507 vm_page_test_dirty(m);
512 vm_page_queues_spin_lock(marker.queue);
515 TAILQ_REMOVE(&vm_page_queues[marker.queue].pl,
517 vm_page_queues_spin_unlock(marker.queue);
520 if (vmstats.v_free_count + vmstats.v_cache_count + pq_active_clean +
521 pq_inactive_clean + vm_swap_size < aligned_nblks + nswap_lowat) {
522 mtx_unlock(&swap_mtx);
527 * Prevent further allocations on this device
529 sp->sw_flags |= SW_CLOSING;
530 for (dvbase = SWB_DMMAX; dvbase < aligned_nblks; dvbase += SWB_DMMAX) {
531 blk = min(aligned_nblks - dvbase, SWB_DMMAX);
532 vsbase = index * SWB_DMMAX + dvbase * nswdev;
533 vm_swap_size -= blist_fill(swapblist, vsbase, blk);
538 * Page in the contents of the device and close it.
540 if (swap_pager_swapoff(index) && swap_pager_swapoff(index)) {
541 mtx_unlock(&swap_mtx);
545 vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY);
546 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, NULL);
547 vn_unlock(sp->sw_vp);
549 bzero(swdevt + index, sizeof(struct swdevt));
552 * Resize the bitmap based on the nem largest swap device,
553 * or free the bitmap if there are no more devices.
555 for (sp = swdevt, aligned_nblks = 0; sp < swdevt + nswdev; sp++) {
557 aligned_nblks = max(aligned_nblks, sp->sw_nblks);
560 nswap = aligned_nblks * nswdev;
563 blist_destroy(swapblist);
568 blist_resize(&swapblist, nswap, 0);
571 mtx_unlock(&swap_mtx);
576 * Account for swap space in individual swdevt's. The caller ensures
577 * that the provided range falls into a single swdevt.
580 * -count space allocated
583 swapacctspace(swblk_t base, swblk_t count)
588 vm_swap_size += count;
589 seg = base / SWB_DMMAX;
590 index = seg % nswdev;
591 swdevt[index].sw_nused -= count;
598 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS)
606 for (n = 0; n < nswdev; ++n) {
609 xs.xsw_size = sizeof(xs);
610 xs.xsw_version = XSWDEV_VERSION;
611 xs.xsw_blksize = PAGE_SIZE;
612 xs.xsw_dev = sp->sw_dev;
613 xs.xsw_flags = sp->sw_flags;
614 xs.xsw_nblks = sp->sw_nblks;
615 xs.xsw_used = sp->sw_nused;
617 error = SYSCTL_OUT(req, &xs, sizeof(xs));
624 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswdev, 0,
625 "Number of swap devices");
626 SYSCTL_NODE(_vm, OID_AUTO, swap_info_array, CTLFLAG_RD, sysctl_vm_swap_info,
627 "Swap statistics by device");