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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 1.36 2007/07/20 17:21:54 dillon 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 struct swdevt *swdevt = should_be_malloced; /* exported to pstat/systat */
69 static int nswap; /* first block after the interleaved devs */
70 int nswdev = NSWAPDEV; /* exported to pstat/systat */
73 static int swapdev_strategy (struct vop_strategy_args *ap);
74 struct vnode *swapdev_vp;
79 * vn_strategy() for swapdev_vp.
80 * Perform swap strategy interleave device selection.
82 * The bp is expected to be locked and on call.
84 * (struct vnode *a_vp, struct bio *b_bio)
88 swapdev_strategy(struct vop_strategy_args *ap)
90 struct bio *bio = ap->a_bio;
92 struct buf *bp = bio->bio_buf;
93 int sz, off, seg, index, blkno, nblkno;
98 sz = howmany(bp->b_bcount, PAGE_SIZE);
99 blkno = (int)(bio->bio_offset >> PAGE_SHIFT);
102 * Convert interleaved swap into per-device swap. Note that
103 * the block size is left in PAGE_SIZE'd chunks (for the newswap)
106 nbio = push_bio(bio);
109 if (off + sz > dmmax) {
110 bp->b_error = EINVAL;
111 bp->b_flags |= B_ERROR;
116 index = seg % nswdev;
118 nbio->bio_offset = (off_t)(seg * dmmax + off) << PAGE_SHIFT;
121 nbio->bio_offset = bio->bio_offset;
123 nblkno = (int)(nbio->bio_offset >> PAGE_SHIFT);
125 if (nblkno + sz > sp->sw_nblks) {
126 bp->b_error = EINVAL;
127 bp->b_flags |= B_ERROR;
128 /* I/O was never started on nbio, must biodone(bio) */
132 if (sp->sw_vp == NULL) {
133 bp->b_error = ENODEV;
134 bp->b_flags |= B_ERROR;
135 /* I/O was never started on nbio, must biodone(bio) */
141 * Issue a strategy call on the appropriate swap vnode. Note that
142 * bp->b_vp is not modified. Strategy code is always supposed to
145 * We have to use vn_strategy() here even if we know we have a
146 * device in order to properly break up requests which exceed the
147 * device's DMA limits.
149 vn_strategy(sp->sw_vp, nbio);
154 * Create a special vnode op vector for swapdev_vp - we only use
155 * vn_strategy(), everything else returns an error.
157 static struct vop_ops swapdev_vnode_vops = {
158 .vop_default = vop_defaultop,
159 .vop_strategy = swapdev_strategy
161 static struct vop_ops *swapdev_vnode_vops_p = &swapdev_vnode_vops;
163 VNODEOP_SET(swapdev_vnode_vops);
166 * swapon_args(char *name)
168 * System call swapon(name) enables swapping on device name,
169 * which must be in the swdevsw. Return EBUSY
170 * if already swapping on this device.
174 sys_swapon(struct swapon_args *uap)
176 struct thread *td = curthread;
179 struct nlookupdata nd;
183 KKASSERT(td->td_proc);
184 cred = td->td_proc->p_ucred;
191 error = nlookup_init(&nd, uap->name, UIO_USERSPACE, NLC_FOLLOW);
193 error = nlookup(&nd);
195 error = cache_vref(&nd.nl_nch, nd.nl_cred, &vp);
200 if (vn_isdisk(vp, &error))
201 error = swaponvp(td, vp, 0);
202 else if (vp->v_type == VREG && vp->v_tag == VT_NFS &&
203 (error = VOP_GETATTR(vp, &attr)) == 0) {
205 * Allow direct swapping to NFS regular files in the same
206 * way that nfs_mountroot() sets up diskless swapping.
208 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE);
218 * Swfree(index) frees the index'th portion of the swap map.
219 * Each of the nswdev devices provides 1/nswdev'th of the swap
220 * space, which is laid out with blocks of dmmax pages circularly
223 * The new swap code uses page-sized blocks. The old swap code used
224 * DEV_BSIZE'd chunks.
226 * XXX locking when multiple swapon's run in parallel
229 swaponvp(struct thread *td, struct vnode *vp, u_long nblks)
231 u_long aligned_nblks;
242 KKASSERT(td->td_proc);
243 cred = td->td_proc->p_ucred;
246 error = getspecialvnode(VT_NON, NULL, &swapdev_vnode_vops_p,
249 panic("Cannot get vnode for swapdev");
250 swapdev_vp->v_type = VNON; /* Untyped */
251 vx_unlock(swapdev_vp);
254 for (sp = swdevt, index = 0 ; index < nswdev; index++, sp++) {
263 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
264 error = VOP_OPEN(vp, FREAD | FWRITE, cred, NULL);
270 * v_rdev is not valid until after the VOP_OPEN() call. dev_psize()
271 * must be supported if a character device has been specified.
273 if (vp->v_type == VCHR)
278 if (nblks == 0 && dev != NULL) {
279 dpsize = dev_dpsize(dev);
281 VOP_CLOSE(vp, FREAD | FWRITE);
284 if ((u_int64_t)dpsize < 0x100000000ULL)
285 nblks = (u_long)dpsize;
290 VOP_CLOSE(vp, FREAD | FWRITE);
295 * If we go beyond this, we get overflows in the radix
298 if (nblks > 0x40000000 / BLIST_META_RADIX / nswdev) {
299 kprintf("exceeded maximum of %d blocks per swap unit\n",
300 0x40000000 / BLIST_META_RADIX / nswdev);
301 VOP_CLOSE(vp, FREAD | FWRITE);
305 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
306 * First chop nblks off to page-align it, then convert.
308 * sw->sw_nblks is in page-sized chunks now too.
310 nblks &= ~(ctodb(1) - 1);
311 nblks = dbtoc(nblks);
314 sp->sw_dev = dev2udev(dev);
316 sp->sw_flags |= SW_FREED;
317 sp->sw_nblks = nblks;
320 * nblks, nswap, and dmmax are PAGE_SIZE'd parameters now, not
321 * DEV_BSIZE'd. aligned_nblks is used to calculate the
322 * size of the swap bitmap, taking into account the stripe size.
324 aligned_nblks = (nblks + (dmmax - 1)) & ~(u_long)(dmmax - 1);
326 if (aligned_nblks * nswdev > nswap)
327 nswap = aligned_nblks * nswdev;
329 if (swapblist == NULL)
330 swapblist = blist_create(nswap);
332 blist_resize(&swapblist, nswap, 0);
334 for (dvbase = dmmax; dvbase < nblks; dvbase += dmmax) {
335 blk = min(nblks - dvbase, dmmax);
336 vsbase = index * dmmax + dvbase * nswdev;
337 blist_free(swapblist, vsbase, blk);
340 swap_pager_newswap();