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33 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94
34 * $FreeBSD: src/sys/vm/vm_swap.c,v 1.96.2.2 2001/10/14 18:46:47 iedowse Exp $
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/sysproto.h>
44 #include <sys/namei.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>
54 #include <vm/vm_extern.h>
55 #include <vm/swap_pager.h>
56 #include <vm/vm_zone.h>
59 * Indirect driver for multi-controller paging.
65 static struct swdevt should_be_malloced[NSWAPDEV];
66 static struct swdevt *swdevt = should_be_malloced;
67 static int nswap; /* first block after the interleaved devs */
68 static int nswdev = NSWAPDEV;
71 static int swapdev_strategy __P((struct vop_strategy_args *ap));
72 struct vnode *swapdev_vp;
77 * VOP_STRATEGY() for swapdev_vp.
78 * Perform swap strategy interleave device selection.
80 * The bp is expected to be locked and *not* B_DONE on call.
85 struct vop_strategy_args /* {
90 int s, sz, off, seg, index;
91 register struct swdevt *sp;
96 sz = howmany(bp->b_bcount, PAGE_SIZE);
99 * Convert interleaved swap into per-device swap. Note that
100 * the block size is left in PAGE_SIZE'd chunks (for the newswap)
104 off = bp->b_blkno % dmmax;
105 if (off + sz > dmmax) {
106 bp->b_error = EINVAL;
107 bp->b_flags |= B_ERROR;
111 seg = bp->b_blkno / dmmax;
112 index = seg % nswdev;
114 bp->b_blkno = seg * dmmax + off;
119 if (bp->b_blkno + sz > sp->sw_nblks) {
120 bp->b_error = EINVAL;
121 bp->b_flags |= B_ERROR;
125 bp->b_dev = sp->sw_device;
126 if (sp->sw_vp == NULL) {
127 bp->b_error = ENODEV;
128 bp->b_flags |= B_ERROR;
134 * Convert from PAGE_SIZE'd to DEV_BSIZE'd chunks for the actual I/O
136 bp->b_blkno = ctodb(bp->b_blkno);
140 if ((bp->b_flags & B_READ) == 0) {
144 if ((vp->v_flag & VBWAIT) && vp->v_numoutput <= 0) {
145 vp->v_flag &= ~VBWAIT;
146 wakeup(&vp->v_numoutput);
149 sp->sw_vp->v_numoutput++;
151 pbreassignbuf(bp, sp->sw_vp);
153 VOP_STRATEGY(bp->b_vp, bp);
158 * Create a special vnode op vector for swapdev_vp - we only use
159 * VOP_STRATEGY(), everything else returns an error.
161 vop_t **swapdev_vnodeop_p;
162 static struct vnodeopv_entry_desc swapdev_vnodeop_entries[] = {
163 { &vop_default_desc, (vop_t *) vop_defaultop },
164 { &vop_strategy_desc, (vop_t *) swapdev_strategy },
167 static struct vnodeopv_desc swapdev_vnodeop_opv_desc =
168 { &swapdev_vnodeop_p, swapdev_vnodeop_entries };
170 VNODEOP_SET(swapdev_vnodeop_opv_desc);
173 * System call swapon(name) enables swapping on device name,
174 * which must be in the swdevsw. Return EBUSY
175 * if already swapping on this device.
177 #ifndef _SYS_SYSPROTO_H_
187 struct swapon_args *uap;
190 register struct vnode *vp;
198 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, p);
203 NDFREE(&nd, NDF_ONLY_PNBUF);
206 if (vn_isdisk(vp, &error))
207 error = swaponvp(p, vp, vp->v_rdev, 0);
208 else if (vp->v_type == VREG && vp->v_tag == VT_NFS &&
209 (error = VOP_GETATTR(vp, &attr, p->p_ucred, p)) == 0) {
211 * Allow direct swapping to NFS regular files in the same
212 * way that nfs_mountroot() sets up diskless swapping.
214 error = swaponvp(p, vp, NODEV, attr.va_size / DEV_BSIZE);
224 * Swfree(index) frees the index'th portion of the swap map.
225 * Each of the nswdev devices provides 1/nswdev'th of the swap
226 * space, which is laid out with blocks of dmmax pages circularly
229 * The new swap code uses page-sized blocks. The old swap code used
230 * DEV_BSIZE'd chunks.
232 * XXX locking when multiple swapon's run in parallel
235 swaponvp(p, vp, dev, nblks)
242 register struct swdevt *sp;
243 register swblk_t vsbase;
247 u_long aligned_nblks;
250 error = getnewvnode(VT_NON, NULL, swapdev_vnodeop_p,
253 panic("Cannot get vnode for swapdev");
254 swapdev_vp->v_type = VNON; /* Untyped */
257 ASSERT_VOP_UNLOCKED(vp, "swaponvp");
258 for (sp = swdevt, index = 0 ; index < nswdev; index++, sp++) {
267 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
268 error = VOP_OPEN(vp, FREAD | FWRITE, p->p_ucred, p);
269 (void) VOP_UNLOCK(vp, 0, p);
273 if (nblks == 0 && dev != NODEV && (devsw(dev)->d_psize == 0 ||
274 (nblks = (*devsw(dev)->d_psize) (dev)) == -1)) {
275 (void) VOP_CLOSE(vp, FREAD | FWRITE, p->p_ucred, p);
279 (void) VOP_CLOSE(vp, FREAD | FWRITE, p->p_ucred, p);
284 * If we go beyond this, we get overflows in the radix
287 if (nblks > 0x40000000 / BLIST_META_RADIX / nswdev) {
288 printf("exceeded maximum of %d blocks per swap unit\n",
289 0x40000000 / BLIST_META_RADIX / nswdev);
290 (void) VOP_CLOSE(vp, FREAD | FWRITE, p->p_ucred, p);
294 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
295 * First chop nblks off to page-align it, then convert.
297 * sw->sw_nblks is in page-sized chunks now too.
299 nblks &= ~(ctodb(1) - 1);
300 nblks = dbtoc(nblks);
303 sp->sw_dev = dev2udev(dev);
305 sp->sw_flags |= SW_FREED;
306 sp->sw_nblks = nblks;
309 * nblks, nswap, and dmmax are PAGE_SIZE'd parameters now, not
310 * DEV_BSIZE'd. aligned_nblks is used to calculate the
311 * size of the swap bitmap, taking into account the stripe size.
313 aligned_nblks = (nblks + (dmmax - 1)) & ~(u_long)(dmmax - 1);
315 if (aligned_nblks * nswdev > nswap)
316 nswap = aligned_nblks * nswdev;
318 if (swapblist == NULL)
319 swapblist = blist_create(nswap);
321 blist_resize(&swapblist, nswap, 0);
323 for (dvbase = dmmax; dvbase < nblks; dvbase += dmmax) {
324 blk = min(nblks - dvbase, dmmax);
325 vsbase = index * dmmax + dvbase * nswdev;
326 blist_free(swapblist, vsbase, blk);