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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 $
35 * $DragonFly: src/sys/vm/vm_swap.c,v 1.18 2005/06/02 20:57:21 swildner Exp $
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/sysproto.h>
45 #include <sys/nlookup.h>
46 #include <sys/dmap.h> /* XXX */
47 #include <sys/vnode.h>
48 #include <sys/fcntl.h>
49 #include <sys/blist.h>
50 #include <sys/kernel.h>
54 #include <sys/thread2.h>
56 #include <vm/vm_extern.h>
57 #include <vm/swap_pager.h>
58 #include <vm/vm_zone.h>
61 * Indirect driver for multi-controller paging.
67 static struct swdevt should_be_malloced[NSWAPDEV];
68 static struct swdevt *swdevt = should_be_malloced;
69 static int nswap; /* first block after the interleaved devs */
70 static int nswdev = NSWAPDEV;
73 static int swapdev_strategy (struct vop_strategy_args *ap);
74 struct vnode *swapdev_vp;
79 * VOP_STRATEGY() for swapdev_vp.
80 * Perform swap strategy interleave device selection.
82 * The bp is expected to be locked and *not* B_DONE on call.
86 swapdev_strategy(struct vop_strategy_args /* {
91 int sz, off, seg, index;
97 sz = howmany(bp->b_bcount, PAGE_SIZE);
100 * Convert interleaved swap into per-device swap. Note that
101 * the block size is left in PAGE_SIZE'd chunks (for the newswap)
105 off = bp->b_blkno % dmmax;
106 if (off + sz > dmmax) {
107 bp->b_error = EINVAL;
108 bp->b_flags |= B_ERROR;
112 seg = bp->b_blkno / dmmax;
113 index = seg % nswdev;
115 bp->b_blkno = seg * dmmax + off;
120 if (bp->b_blkno + sz > sp->sw_nblks) {
121 bp->b_error = EINVAL;
122 bp->b_flags |= B_ERROR;
126 bp->b_dev = sp->sw_device;
127 if (sp->sw_vp == NULL) {
128 bp->b_error = ENODEV;
129 bp->b_flags |= B_ERROR;
135 * Convert from PAGE_SIZE'd to DEV_BSIZE'd chunks for the actual I/O
137 bp->b_blkno = ctodb(bp->b_blkno);
141 if ((bp->b_flags & B_READ) == 0) {
145 if ((vp->v_flag & VBWAIT) && vp->v_numoutput <= 0) {
146 vp->v_flag &= ~VBWAIT;
147 wakeup(&vp->v_numoutput);
150 sp->sw_vp->v_numoutput++;
152 pbreassignbuf(bp, sp->sw_vp);
154 VOP_STRATEGY(bp->b_vp, bp);
159 * Create a special vnode op vector for swapdev_vp - we only use
160 * VOP_STRATEGY(), everything else returns an error.
162 struct vop_ops *swapdev_vnode_vops;
163 static struct vnodeopv_entry_desc swapdev_vnodeop_entries[] = {
164 { &vop_default_desc, vop_defaultop },
165 { &vop_strategy_desc, (void *) swapdev_strategy },
168 static struct vnodeopv_desc swapdev_vnodeop_opv_desc =
169 { &swapdev_vnode_vops, swapdev_vnodeop_entries };
171 VNODEOP_SET(swapdev_vnodeop_opv_desc);
174 * swapon_args(char *name)
176 * System call swapon(name) enables swapping on device name,
177 * which must be in the swdevsw. Return EBUSY
178 * if already swapping on this device.
182 swapon(struct swapon_args *uap)
184 struct thread *td = curthread;
187 struct nlookupdata nd;
191 KKASSERT(td->td_proc);
192 cred = td->td_proc->p_ucred;
199 error = nlookup_init(&nd, uap->name, UIO_USERSPACE, NLC_FOLLOW);
201 error = nlookup(&nd);
203 error = cache_vref(nd.nl_ncp, nd.nl_cred, &vp);
208 if (vn_isdisk(vp, &error))
209 error = swaponvp(td, vp, 0);
210 else if (vp->v_type == VREG && vp->v_tag == VT_NFS &&
211 (error = VOP_GETATTR(vp, &attr, td)) == 0) {
213 * Allow direct swapping to NFS regular files in the same
214 * way that nfs_mountroot() sets up diskless swapping.
216 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE);
226 * Swfree(index) frees the index'th portion of the swap map.
227 * Each of the nswdev devices provides 1/nswdev'th of the swap
228 * space, which is laid out with blocks of dmmax pages circularly
231 * The new swap code uses page-sized blocks. The old swap code used
232 * DEV_BSIZE'd chunks.
234 * XXX locking when multiple swapon's run in parallel
237 swaponvp(struct thread *td, struct vnode *vp, u_long nblks)
239 u_long aligned_nblks;
249 KKASSERT(td->td_proc);
250 cred = td->td_proc->p_ucred;
253 error = getspecialvnode(VT_NON, NULL, &swapdev_vnode_vops,
256 panic("Cannot get vnode for swapdev");
257 swapdev_vp->v_type = VNON; /* Untyped */
258 vx_unlock(swapdev_vp);
261 ASSERT_VOP_UNLOCKED(vp, "swaponvp");
262 for (sp = swdevt, index = 0 ; index < nswdev; index++, sp++) {
271 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
272 error = VOP_OPEN(vp, FREAD | FWRITE, cred, NULL, td);
273 VOP_UNLOCK(vp, 0, td);
278 * v_rdev is not valid until after the VOP_OPEN() call. dev_psize()
279 * must be supported if a character device has been specified.
281 if (vp->v_type == VCHR)
286 if (nblks == 0 && dev != NODEV && ((nblks = dev_dpsize(dev)) == -1)) {
287 (void) VOP_CLOSE(vp, FREAD | FWRITE, td);
291 (void) VOP_CLOSE(vp, FREAD | FWRITE, td);
296 * If we go beyond this, we get overflows in the radix
299 if (nblks > 0x40000000 / BLIST_META_RADIX / nswdev) {
300 printf("exceeded maximum of %d blocks per swap unit\n",
301 0x40000000 / BLIST_META_RADIX / nswdev);
302 (void) VOP_CLOSE(vp, FREAD | FWRITE, td);
306 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
307 * First chop nblks off to page-align it, then convert.
309 * sw->sw_nblks is in page-sized chunks now too.
311 nblks &= ~(ctodb(1) - 1);
312 nblks = dbtoc(nblks);
315 sp->sw_dev = dev2udev(dev);
317 sp->sw_flags |= SW_FREED;
318 sp->sw_nblks = nblks;
321 * nblks, nswap, and dmmax are PAGE_SIZE'd parameters now, not
322 * DEV_BSIZE'd. aligned_nblks is used to calculate the
323 * size of the swap bitmap, taking into account the stripe size.
325 aligned_nblks = (nblks + (dmmax - 1)) & ~(u_long)(dmmax - 1);
327 if (aligned_nblks * nswdev > nswap)
328 nswap = aligned_nblks * nswdev;
330 if (swapblist == NULL)
331 swapblist = blist_create(nswap);
333 blist_resize(&swapblist, nswap, 0);
335 for (dvbase = dmmax; dvbase < nblks; dvbase += dmmax) {
336 blk = min(nblks - dvbase, dmmax);
337 vsbase = index * dmmax + dvbase * nswdev;
338 blist_free(swapblist, vsbase, blk);