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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/mplock2.h>
62 #include <sys/mutex2.h>
63 #include <sys/spinlock2.h>
66 * Indirect driver for multi-controller paging.
72 static struct swdevt should_be_malloced[NSWAPDEV];
73 struct swdevt *swdevt = should_be_malloced; /* exported to pstat/systat */
74 static swblk_t nswap; /* first block after the interleaved devs */
75 static struct mtx swap_mtx = MTX_INITIALIZER;
76 int nswdev = NSWAPDEV; /* exported to pstat/systat */
80 static int swapoff_one(int index);
81 struct vnode *swapdev_vp;
84 * (struct vnode *a_vp, struct bio *b_bio)
86 * vn_strategy() for swapdev_vp. Perform swap strategy interleave device
92 swapdev_strategy(struct vop_strategy_args *ap)
94 struct bio *bio = ap->a_bio;
96 struct buf *bp = bio->bio_buf;
97 int sz, off, seg, index, blkno, nblkno;
99 sz = howmany(bp->b_bcount, PAGE_SIZE);
100 blkno = (int)(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);
110 if (off + sz > dmmax) {
111 bp->b_error = EINVAL;
112 bp->b_flags |= B_ERROR;
117 index = seg % nswdev;
119 nbio->bio_offset = (off_t)(seg * dmmax + off) << PAGE_SHIFT;
122 nbio->bio_offset = bio->bio_offset;
124 nblkno = (int)(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);
206 error = nlookup_init(&nd, uap->name, UIO_USERSPACE, NLC_FOLLOW);
208 error = nlookup(&nd);
210 error = cache_vref(&nd.nl_nch, nd.nl_cred, &vp);
214 mtx_unlock(&swap_mtx);
218 if (vn_isdisk(vp, &error)) {
219 error = swaponvp(td, vp, 0);
220 } else if (vp->v_type == VREG && vp->v_tag == VT_NFS &&
221 (error = VOP_GETATTR(vp, &attr)) == 0) {
223 * Allow direct swapping to NFS regular files in the same
224 * way that nfs_mountroot() sets up diskless swapping.
226 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE);
231 mtx_unlock(&swap_mtx);
237 * Swfree(index) frees the index'th portion of the swap map.
238 * Each of the nswdev devices provides 1/nswdev'th of the swap
239 * space, which is laid out with blocks of dmmax pages circularly
242 * The new swap code uses page-sized blocks. The old swap code used
243 * DEV_BSIZE'd chunks.
245 * XXX locking when multiple swapon's run in parallel
248 swaponvp(struct thread *td, struct vnode *vp, u_quad_t nblks)
250 swblk_t aligned_nblks;
263 lwkt_gettoken(&vm_token); /* needed for vm_swap_size and blist */
267 error = getspecialvnode(VT_NON, NULL, &swapdev_vnode_vops_p,
270 panic("Cannot get vnode for swapdev");
271 swapdev_vp->v_type = VNON; /* Untyped */
272 vx_unlock(swapdev_vp);
275 for (sp = swdevt, index = 0 ; index < nswdev; index++, sp++) {
276 if (sp->sw_vp == vp) {
287 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
288 error = VOP_OPEN(vp, FREAD | FWRITE, cred, NULL);
294 * v_rdev is not valid until after the VOP_OPEN() call. dev_psize()
295 * must be supported if a character device has been specified.
297 if (vp->v_type == VCHR)
302 if (nblks == 0 && dev != NULL) {
303 dpsize = dev_dpsize(dev);
305 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
306 VOP_CLOSE(vp, FREAD | FWRITE, NULL);
311 nblks = (u_quad_t)dpsize;
314 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
315 VOP_CLOSE(vp, FREAD | FWRITE, NULL);
322 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
323 * First chop nblks off to page-align it, then convert.
325 * sw->sw_nblks is in page-sized chunks now too.
327 nblks &= ~(u_quad_t)(ctodb(1) - 1);
328 nblks = dbtoc(nblks);
331 * Post-conversion nblks must not be >= BLIST_MAXBLKS, and
332 * we impose a 4-swap-device limit so we have to divide it out
333 * further. Going beyond this will result in overflows in the
336 * Post-conversion nblks must fit within a (swblk_t), which
337 * this test also ensures.
339 if (nblks > BLIST_MAXBLKS / nswdev) {
340 kprintf("exceeded maximum of %d blocks per swap unit\n",
341 (int)BLIST_MAXBLKS / nswdev);
342 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
343 VOP_CLOSE(vp, FREAD | FWRITE, NULL);
350 sp->sw_dev = dev2udev(dev);
352 sp->sw_flags = SW_FREED;
356 * nblks, nswap, and dmmax are PAGE_SIZE'd parameters now, not
357 * DEV_BSIZE'd. aligned_nblks is used to calculate the
358 * size of the swap bitmap, taking into account the stripe size.
360 aligned_nblks = (swblk_t)((nblks + (dmmax - 1)) & ~(u_long)(dmmax - 1));
361 sp->sw_nblks = aligned_nblks;
363 if (aligned_nblks * nswdev > nswap)
364 nswap = aligned_nblks * nswdev;
366 if (swapblist == NULL)
367 swapblist = blist_create(nswap);
369 blist_resize(&swapblist, nswap, 0);
371 for (dvbase = dmmax; dvbase < aligned_nblks; dvbase += dmmax) {
372 blk = min(aligned_nblks - dvbase, dmmax);
373 vsbase = index * dmmax + dvbase * nswdev;
374 blist_free(swapblist, vsbase, blk);
378 swap_pager_newswap();
381 mtx_unlock(&swap_mtx);
382 lwkt_reltoken(&vm_token);
387 * swapoff_args(char *name)
389 * System call swapoff(name) disables swapping on device name,
390 * which must be an active swap device. Return ENOMEM
391 * if there is not enough memory to page in the contents of
397 sys_swapoff(struct swapoff_args *uap)
400 struct nlookupdata nd;
404 error = priv_check(curthread, PRIV_ROOT);
411 error = nlookup_init(&nd, uap->name, UIO_USERSPACE, NLC_FOLLOW);
413 error = nlookup(&nd);
415 error = cache_vref(&nd.nl_nch, nd.nl_cred, &vp);
420 for (sp = swdevt, index = 0; index < nswdev; index++, sp++) {
427 error = swapoff_one(index);
431 mtx_unlock(&swap_mtx);
436 swapoff_one(int index)
438 swblk_t blk, aligned_nblks;
439 swblk_t dvbase, vsbase;
440 u_int pq_active_clean, pq_inactive_clean;
442 struct vm_page marker;
449 aligned_nblks = sp->sw_nblks;
450 pq_active_clean = pq_inactive_clean = 0;
453 * We can turn off this swap device safely only if the
454 * available virtual memory in the system will fit the amount
455 * of data we will have to page back in, plus an epsilon so
456 * the system doesn't become critically low on swap space.
458 for (q = 0; q < PQ_L2_SIZE; ++q) {
459 bzero(&marker, sizeof(marker));
460 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER;
461 marker.queue = PQ_ACTIVE + q;
463 marker.wire_count = 1;
465 vm_page_queues_spin_lock(marker.queue);
466 TAILQ_INSERT_HEAD(&vm_page_queues[marker.queue].pl,
469 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL) {
470 TAILQ_REMOVE(&vm_page_queues[marker.queue].pl,
472 TAILQ_INSERT_AFTER(&vm_page_queues[marker.queue].pl, m,
474 if (m->flags & (PG_MARKER | PG_FICTITIOUS))
477 if (vm_page_busy_try(m, FALSE) == 0) {
478 vm_page_queues_spin_unlock(marker.queue);
480 vm_page_test_dirty(m);
485 vm_page_queues_spin_lock(marker.queue);
488 TAILQ_REMOVE(&vm_page_queues[marker.queue].pl, &marker, pageq);
489 vm_page_queues_spin_unlock(marker.queue);
491 marker.queue = PQ_INACTIVE + q;
493 vm_page_queues_spin_lock(marker.queue);
494 TAILQ_INSERT_HEAD(&vm_page_queues[marker.queue].pl,
497 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL) {
499 &vm_page_queues[marker.queue].pl,
502 &vm_page_queues[marker.queue].pl,
504 if (m->flags & (PG_MARKER | PG_FICTITIOUS))
507 if (vm_page_busy_try(m, FALSE) == 0) {
508 vm_page_queues_spin_unlock(marker.queue);
510 vm_page_test_dirty(m);
515 vm_page_queues_spin_lock(marker.queue);
518 TAILQ_REMOVE(&vm_page_queues[marker.queue].pl,
520 vm_page_queues_spin_unlock(marker.queue);
523 if (vmstats.v_free_count + vmstats.v_cache_count + pq_active_clean +
524 pq_inactive_clean + vm_swap_size < aligned_nblks + nswap_lowat) {
525 mtx_unlock(&swap_mtx);
530 * Prevent further allocations on this device
532 sp->sw_flags |= SW_CLOSING;
533 for (dvbase = dmmax; dvbase < aligned_nblks; dvbase += dmmax) {
534 blk = min(aligned_nblks - dvbase, dmmax);
535 vsbase = index * dmmax + dvbase * nswdev;
536 vm_swap_size -= blist_fill(swapblist, vsbase, blk);
541 * Page in the contents of the device and close it.
543 if (swap_pager_swapoff(index) && swap_pager_swapoff(index)) {
544 mtx_unlock(&swap_mtx);
548 vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY);
549 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, NULL);
550 vn_unlock(sp->sw_vp);
552 bzero(swdevt + index, sizeof(struct swdevt));
555 * Resize the bitmap based on the nem largest swap device,
556 * or free the bitmap if there are no more devices.
558 for (sp = swdevt, aligned_nblks = 0; sp < swdevt + nswdev; sp++) {
560 aligned_nblks = max(aligned_nblks, sp->sw_nblks);
563 nswap = aligned_nblks * nswdev;
566 blist_destroy(swapblist);
571 blist_resize(&swapblist, nswap, 0);
574 mtx_unlock(&swap_mtx);
579 * Account for swap space in individual swdevt's. The caller ensures
580 * that the provided range falls into a single swdevt.
583 * -count space allocated
586 swapacctspace(swblk_t base, swblk_t count)
591 vm_swap_size += count;
593 index = seg % nswdev;
594 swdevt[index].sw_nused -= count;
601 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS)
609 for (n = 0; n < nswdev; ++n) {
612 xs.xsw_size = sizeof(xs);
613 xs.xsw_version = XSWDEV_VERSION;
614 xs.xsw_blksize = PAGE_SIZE;
615 xs.xsw_dev = sp->sw_dev;
616 xs.xsw_flags = sp->sw_flags;
617 xs.xsw_nblks = sp->sw_nblks;
618 xs.xsw_used = sp->sw_nused;
620 error = SYSCTL_OUT(req, &xs, sizeof(xs));
627 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswdev, 0,
628 "Number of swap devices");
629 SYSCTL_NODE(_vm, OID_AUTO, swap_info_array, CTLFLAG_RD, sysctl_vm_swap_info,
630 "Swap statistics by device");