xref: /freebsd/sys/dev/md/md.c (revision c68159a6d8eede11766cf13896d0f7670dbd51aa)
1 /*
2  * ----------------------------------------------------------------------------
3  * "THE BEER-WARE LICENSE" (Revision 42):
4  * <phk@FreeBSD.ORG> wrote this file.  As long as you retain this notice you
5  * can do whatever you want with this stuff. If we meet some day, and you think
6  * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
7  * ----------------------------------------------------------------------------
8  *
9  * $FreeBSD$
10  *
11  */
12 
13 /*
14  * The following functions are based in the vn(4) driver: mdstart_swap(),
15  * mdstart_vnode(), mdcreate_swap(), mdcreate_vnode() and mddestroy(),
16  * and as such under the following copyright:
17  *
18  * Copyright (c) 1988 University of Utah.
19  * Copyright (c) 1990, 1993
20  *	The Regents of the University of California.  All rights reserved.
21  *
22  * This code is derived from software contributed to Berkeley by
23  * the Systems Programming Group of the University of Utah Computer
24  * Science Department.
25  *
26  * Redistribution and use in source and binary forms, with or without
27  * modification, are permitted provided that the following conditions
28  * are met:
29  * 1. Redistributions of source code must retain the above copyright
30  *    notice, this list of conditions and the following disclaimer.
31  * 2. Redistributions in binary form must reproduce the above copyright
32  *    notice, this list of conditions and the following disclaimer in the
33  *    documentation and/or other materials provided with the distribution.
34  * 3. All advertising materials mentioning features or use of this software
35  *    must display the following acknowledgement:
36  *	This product includes software developed by the University of
37  *	California, Berkeley and its contributors.
38  * 4. Neither the name of the University nor the names of its contributors
39  *    may be used to endorse or promote products derived from this software
40  *    without specific prior written permission.
41  *
42  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
43  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
44  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
45  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
46  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
47  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
48  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
49  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
50  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
51  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52  * SUCH DAMAGE.
53  *
54  * from: Utah Hdr: vn.c 1.13 94/04/02
55  *
56  *	from: @(#)vn.c	8.6 (Berkeley) 4/1/94
57  * From: src/sys/dev/vn/vn.c,v 1.122 2000/12/16 16:06:03
58  */
59 
60 #include "opt_mfs.h"		/* We have adopted some tasks from MFS */
61 #include "opt_md.h"
62 
63 #include <sys/param.h>
64 #include <sys/systm.h>
65 #include <sys/bio.h>
66 #include <sys/conf.h>
67 #include <sys/devicestat.h>
68 #include <sys/disk.h>
69 #include <sys/kernel.h>
70 #include <sys/malloc.h>
71 #include <sys/sysctl.h>
72 #include <sys/linker.h>
73 #include <sys/queue.h>
74 #include <sys/mdioctl.h>
75 #include <sys/vnode.h>
76 #include <sys/namei.h>
77 #include <sys/fcntl.h>
78 #include <sys/proc.h>
79 #include <machine/atomic.h>
80 
81 #include <vm/vm.h>
82 #include <vm/vm_object.h>
83 #include <vm/vm_page.h>
84 #include <vm/vm_pager.h>
85 #include <vm/vm_zone.h>
86 #include <vm/swap_pager.h>
87 
88 #ifndef MD_NSECT
89 #define MD_NSECT (10000 * 2)
90 #endif
91 
92 MALLOC_DEFINE(M_MD, "MD disk", "Memory Disk");
93 MALLOC_DEFINE(M_MDSECT, "MD sectors", "Memory Disk Sectors");
94 
95 static int md_debug;
96 SYSCTL_INT(_debug, OID_AUTO, mddebug, CTLFLAG_RW, &md_debug, 0, "");
97 
98 #if defined(MFS_ROOT) && !defined(MD_ROOT)
99 #define MD_ROOT MFS_ROOT
100 #warning "option MFS_ROOT has been superceeded by MD_ROOT"
101 #endif
102 
103 #if defined(MFS_ROOT_SIZE) && !defined(MD_ROOT_SIZE)
104 #define MD_ROOT_SIZE MFS_ROOT_SIZE
105 #warning "option MFS_ROOT_SIZE has been superceeded by MD_ROOT_SIZE"
106 #endif
107 
108 #if defined(MD_ROOT) && defined(MD_ROOT_SIZE)
109 /* Image gets put here: */
110 static u_char mfs_root[MD_ROOT_SIZE*1024] = "MFS Filesystem goes here";
111 static u_char end_mfs_root[] __unused = "MFS Filesystem had better STOP here";
112 #endif
113 
114 static int mdrootready;
115 static int mdunits;
116 
117 #define CDEV_MAJOR	95
118 
119 static d_strategy_t mdstrategy;
120 static d_open_t mdopen;
121 static d_ioctl_t mdioctl, mdctlioctl;
122 
123 static struct cdevsw md_cdevsw = {
124         /* open */      mdopen,
125         /* close */     nullclose,
126         /* read */      physread,
127         /* write */     physwrite,
128         /* ioctl */     mdioctl,
129         /* poll */      nopoll,
130         /* mmap */      nommap,
131         /* strategy */  mdstrategy,
132         /* name */      "md",
133         /* maj */       CDEV_MAJOR,
134         /* dump */      nodump,
135         /* psize */     nopsize,
136         /* flags */     D_DISK | D_CANFREE | D_MEMDISK,
137 };
138 
139 static struct cdevsw mdctl_cdevsw = {
140         /* open */      nullopen,
141         /* close */     nullclose,
142         /* read */      noread,
143         /* write */     nowrite,
144         /* ioctl */     mdctlioctl,
145         /* poll */      nopoll,
146         /* mmap */      nommap,
147         /* strategy */  nostrategy,
148         /* name */      "md",
149         /* maj */       CDEV_MAJOR
150 };
151 
152 static struct cdevsw mddisk_cdevsw;
153 
154 static LIST_HEAD(, md_s) md_softc_list = LIST_HEAD_INITIALIZER(&md_softc_list);
155 
156 struct md_s {
157 	int unit;
158 	LIST_ENTRY(md_s) list;
159 	struct devstat stats;
160 	struct bio_queue_head bio_queue;
161 	struct disk disk;
162 	dev_t dev;
163 	int busy;
164 	enum md_types type;
165 	unsigned nsect;
166 	unsigned secsize;
167 	unsigned flags;
168 
169 	/* MD_MALLOC related fields */
170 	unsigned nsecp;
171 	u_char **secp;
172 
173 	/* MD_PRELOAD related fields */
174 	u_char *pl_ptr;
175 	unsigned pl_len;
176 
177 	/* MD_VNODE related fields */
178 	struct vnode *vnode;
179 	struct ucred *cred;
180 
181 	/* MD_OBJET related fields */
182 	vm_object_t object;
183 };
184 
185 static int
186 mdopen(dev_t dev, int flag, int fmt, struct proc *p)
187 {
188 	struct md_s *sc;
189 	struct disklabel *dl;
190 
191 	if (md_debug)
192 		printf("mdopen(%s %x %x %p)\n",
193 			devtoname(dev), flag, fmt, p);
194 
195 	sc = dev->si_drv1;
196 
197 	dl = &sc->disk.d_label;
198 	bzero(dl, sizeof(*dl));
199 	dl->d_secsize = sc->secsize;
200 	dl->d_nsectors = sc->nsect > 1024 ? 1024 : sc->nsect;
201 	dl->d_ntracks = 1;
202 	dl->d_secpercyl = dl->d_nsectors * dl->d_ntracks;
203 	dl->d_secperunit = sc->nsect;
204 	dl->d_ncylinders = dl->d_secperunit / dl->d_secpercyl;
205 	return (0);
206 }
207 
208 static int
209 mdioctl(dev_t dev, u_long cmd, caddr_t addr, int flags, struct proc *p)
210 {
211 
212 	if (md_debug)
213 		printf("mdioctl(%s %lx %p %x %p)\n",
214 			devtoname(dev), cmd, addr, flags, p);
215 
216 	return (ENOIOCTL);
217 }
218 
219 static void
220 mdstart_malloc(struct md_s *sc)
221 {
222 	int i;
223 	struct bio *bp;
224 	devstat_trans_flags dop;
225 	u_char *secp, **secpp, *dst;
226 	unsigned secno, nsec, secval, uc;
227 
228 	for (;;) {
229 		/* XXX: LOCK(unique unit numbers) */
230 		bp = bioq_first(&sc->bio_queue);
231 		if (bp)
232 			bioq_remove(&sc->bio_queue, bp);
233 		/* XXX: UNLOCK(unique unit numbers) */
234 		if (!bp)
235 			break;
236 
237 		devstat_start_transaction(&sc->stats);
238 
239 		if (bp->bio_cmd == BIO_DELETE)
240 			dop = DEVSTAT_NO_DATA;
241 		else if (bp->bio_cmd == BIO_READ)
242 			dop = DEVSTAT_READ;
243 		else
244 			dop = DEVSTAT_WRITE;
245 
246 		nsec = bp->bio_bcount / DEV_BSIZE;
247 		secno = bp->bio_pblkno;
248 		dst = bp->bio_data;
249 		while (nsec--) {
250 			if (secno < sc->nsecp) {
251 				secpp = &sc->secp[secno];
252 				if ((uintptr_t)*secpp > 255) {
253 					secp = *secpp;
254 					secval = 0;
255 				} else {
256 					secp = 0;
257 					secval = (uintptr_t) *secpp;
258 				}
259 			} else {
260 				secpp = 0;
261 				secp = 0;
262 				secval = 0;
263 			}
264 			if (md_debug > 2)
265 				printf("%x %p %p %d\n",
266 				    bp->bio_flags, secpp, secp, secval);
267 
268 			if (bp->bio_cmd == BIO_DELETE) {
269 				if (secpp && !(sc->flags & MD_RESERVE)) {
270 					if (secp)
271 						FREE(secp, M_MDSECT);
272 					*secpp = 0;
273 				}
274 			} else if (bp->bio_cmd == BIO_READ) {
275 				if (secp) {
276 					bcopy(secp, dst, DEV_BSIZE);
277 				} else if (secval) {
278 					for (i = 0; i < DEV_BSIZE; i++)
279 						dst[i] = secval;
280 				} else {
281 					bzero(dst, DEV_BSIZE);
282 				}
283 			} else {
284 				if (sc->flags & MD_COMPRESS) {
285 					uc = dst[0];
286 					for (i = 1; i < DEV_BSIZE; i++)
287 						if (dst[i] != uc)
288 							break;
289 				} else {
290 					i = 0;
291 					uc = 0;
292 				}
293 				if (i == DEV_BSIZE && !uc) {
294 					if (secp)
295 						FREE(secp, M_MDSECT);
296 					if (secpp)
297 						*secpp = (u_char *)(uintptr_t)uc;
298 				} else {
299 					if (!secpp) {
300 						MALLOC(secpp, u_char **, (secno + nsec + 1) * sizeof(u_char *), M_MD, M_WAITOK | M_ZERO);
301 						bcopy(sc->secp, secpp, sc->nsecp * sizeof(u_char *));
302 						FREE(sc->secp, M_MD);
303 						sc->secp = secpp;
304 						sc->nsecp = secno + nsec + 1;
305 						secpp = &sc->secp[secno];
306 					}
307 					if (i == DEV_BSIZE) {
308 						if (secp)
309 							FREE(secp, M_MDSECT);
310 						*secpp = (u_char *)(uintptr_t)uc;
311 					} else {
312 						if (!secp)
313 							MALLOC(secp, u_char *, DEV_BSIZE, M_MDSECT, M_WAITOK);
314 						bcopy(dst, secp, DEV_BSIZE);
315 						*secpp = secp;
316 					}
317 				}
318 			}
319 			secno++;
320 			dst += DEV_BSIZE;
321 		}
322 		bp->bio_resid = 0;
323 		devstat_end_transaction_bio(&sc->stats, bp);
324 		biodone(bp);
325 	}
326 	return;
327 }
328 
329 
330 static void
331 mdstart_preload(struct md_s *sc)
332 {
333 	struct bio *bp;
334 	devstat_trans_flags dop;
335 
336 	for (;;) {
337 		/* XXX: LOCK(unique unit numbers) */
338 		bp = bioq_first(&sc->bio_queue);
339 		if (bp)
340 			bioq_remove(&sc->bio_queue, bp);
341 		/* XXX: UNLOCK(unique unit numbers) */
342 		if (!bp)
343 			break;
344 
345 		devstat_start_transaction(&sc->stats);
346 
347 		if (bp->bio_cmd == BIO_DELETE) {
348 			dop = DEVSTAT_NO_DATA;
349 		} else if (bp->bio_cmd == BIO_READ) {
350 			dop = DEVSTAT_READ;
351 			bcopy(sc->pl_ptr + (bp->bio_pblkno << DEV_BSHIFT), bp->bio_data, bp->bio_bcount);
352 		} else {
353 			dop = DEVSTAT_WRITE;
354 			bcopy(bp->bio_data, sc->pl_ptr + (bp->bio_pblkno << DEV_BSHIFT), bp->bio_bcount);
355 		}
356 		bp->bio_resid = 0;
357 		devstat_end_transaction_bio(&sc->stats, bp);
358 		biodone(bp);
359 	}
360 	return;
361 }
362 
363 static void
364 mdstart_vnode(struct md_s *sc)
365 {
366 	int error;
367 	struct bio *bp;
368 	struct uio auio;
369 	struct iovec aiov;
370 	struct mount *mp;
371 
372 	/*
373 	 * VNODE I/O
374 	 *
375 	 * If an error occurs, we set BIO_ERROR but we do not set
376 	 * B_INVAL because (for a write anyway), the buffer is
377 	 * still valid.
378 	 */
379 
380 	for (;;) {
381 		/* XXX: LOCK(unique unit numbers) */
382 		bp = bioq_first(&sc->bio_queue);
383 		if (bp)
384 			bioq_remove(&sc->bio_queue, bp);
385 		/* XXX: UNLOCK(unique unit numbers) */
386 		if (!bp)
387 			break;
388 
389 		devstat_start_transaction(&sc->stats);
390 
391 		bzero(&auio, sizeof(auio));
392 
393 		aiov.iov_base = bp->bio_data;
394 		aiov.iov_len = bp->bio_bcount;
395 		auio.uio_iov = &aiov;
396 		auio.uio_iovcnt = 1;
397 		auio.uio_offset = (vm_ooffset_t)bp->bio_pblkno * sc->secsize;
398 		auio.uio_segflg = UIO_SYSSPACE;
399 		if(bp->bio_cmd == BIO_READ)
400 			auio.uio_rw = UIO_READ;
401 		else
402 			auio.uio_rw = UIO_WRITE;
403 		auio.uio_resid = bp->bio_bcount;
404 		auio.uio_procp = curproc;
405 		if (VOP_ISLOCKED(sc->vnode, NULL))
406 			vprint("unexpected vn driver lock", sc->vnode);
407 		if (bp->bio_cmd == BIO_READ) {
408 			vn_lock(sc->vnode, LK_EXCLUSIVE | LK_RETRY, curproc);
409 			error = VOP_READ(sc->vnode, &auio, 0, sc->cred);
410 		} else {
411 			(void) vn_start_write(sc->vnode, &mp, V_WAIT);
412 			vn_lock(sc->vnode, LK_EXCLUSIVE | LK_RETRY, curproc);
413 			error = VOP_WRITE(sc->vnode, &auio, 0, sc->cred);
414 			vn_finished_write(mp);
415 		}
416 		VOP_UNLOCK(sc->vnode, 0, curproc);
417 		bp->bio_resid = auio.uio_resid;
418 
419 		if (error) {
420 			bp->bio_error = error;
421 			bp->bio_flags |= BIO_ERROR;
422 		}
423 		devstat_end_transaction_bio(&sc->stats, bp);
424 		biodone(bp);
425 	}
426 	return;
427 }
428 
429 static void
430 mdstart_swap(struct md_s *sc)
431 {
432 	struct bio *bp;
433 
434 	for (;;) {
435 		/* XXX: LOCK(unique unit numbers) */
436 		bp = bioq_first(&sc->bio_queue);
437 		if (bp)
438 			bioq_remove(&sc->bio_queue, bp);
439 		/* XXX: UNLOCK(unique unit numbers) */
440 		if (!bp)
441 			break;
442 
443 #if 0
444 		devstat_start_transaction(&sc->stats);
445 #endif
446 
447 		if ((bp->bio_cmd == BIO_DELETE) && (sc->flags & MD_RESERVE))
448 			biodone(bp);
449 		else
450 			vm_pager_strategy(sc->object, bp);
451 
452 #if 0
453 		devstat_end_transaction_bio(&sc->stats, bp);
454 #endif
455 	}
456 	return;
457 }
458 
459 static void
460 mdstrategy(struct bio *bp)
461 {
462 	struct md_s *sc;
463 
464 	if (md_debug > 1)
465 		printf("mdstrategy(%p) %s %x, %d, %ld, %p)\n",
466 		    bp, devtoname(bp->bio_dev), bp->bio_flags, bp->bio_blkno,
467 		    bp->bio_bcount / DEV_BSIZE, bp->bio_data);
468 
469 	sc = bp->bio_dev->si_drv1;
470 
471 	/* XXX: LOCK(sc->lock) */
472 	bioqdisksort(&sc->bio_queue, bp);
473 	/* XXX: UNLOCK(sc->lock) */
474 
475 	if (atomic_cmpset_int(&sc->busy, 0, 1) == 0)
476 		return;
477 
478 	switch (sc->type) {
479 	case MD_MALLOC:
480 		mdstart_malloc(sc);
481 		break;
482 	case MD_PRELOAD:
483 		mdstart_preload(sc);
484 		break;
485 	case MD_VNODE:
486 		mdstart_vnode(sc);
487 		break;
488 	case MD_SWAP:
489 		mdstart_swap(sc);
490 		break;
491 	default:
492 		panic("Impossible md(type)");
493 		break;
494 	}
495 	sc->busy = 0;
496 }
497 
498 static struct md_s *
499 mdfind(int unit)
500 {
501 	struct md_s *sc;
502 
503 	/* XXX: LOCK(unique unit numbers) */
504 	LIST_FOREACH(sc, &md_softc_list, list) {
505 		if (sc->unit == unit)
506 			break;
507 	}
508 	/* XXX: UNLOCK(unique unit numbers) */
509 	return (sc);
510 }
511 
512 static struct md_s *
513 mdnew(int unit)
514 {
515 	struct md_s *sc;
516 	int max = -1;
517 
518 	/* XXX: LOCK(unique unit numbers) */
519 	LIST_FOREACH(sc, &md_softc_list, list) {
520 		if (sc->unit == unit) {
521 			/* XXX: UNLOCK(unique unit numbers) */
522 			return (NULL);
523 		}
524 		if (sc->unit > max)
525 			max = sc->unit;
526 	}
527 	if (unit == -1)
528 		unit = max + 1;
529 	if (unit > DKMAXUNIT)
530 		return (NULL);
531 	MALLOC(sc, struct md_s *,sizeof(*sc), M_MD, M_WAITOK | M_ZERO);
532 	sc->unit = unit;
533 	LIST_INSERT_HEAD(&md_softc_list, sc, list);
534 	/* XXX: UNLOCK(unique unit numbers) */
535 	return (sc);
536 }
537 
538 static void
539 mddelete(struct md_s *sc)
540 {
541 
542 	/* XXX: LOCK(unique unit numbers) */
543 	LIST_REMOVE(sc, list);
544 	/* XXX: UNLOCK(unique unit numbers) */
545 	FREE(sc, M_MD);
546 }
547 
548 static void
549 mdinit(struct md_s *sc)
550 {
551 
552 	bioq_init(&sc->bio_queue);
553 	devstat_add_entry(&sc->stats, "md", sc->unit, DEV_BSIZE,
554 		DEVSTAT_NO_ORDERED_TAGS,
555 		DEVSTAT_TYPE_DIRECT | DEVSTAT_TYPE_IF_OTHER,
556 		DEVSTAT_PRIORITY_OTHER);
557 	sc->dev = disk_create(sc->unit, &sc->disk, 0, &md_cdevsw, &mddisk_cdevsw);
558 	sc->dev->si_drv1 = sc;
559 }
560 
561 static int
562 mdcreate_preload(struct md_ioctl *mdio)
563 {
564 	struct md_s *sc;
565 
566 	if (mdio->md_size == 0)
567 		return(EINVAL);
568 	if (mdio->md_options & ~(MD_AUTOUNIT))
569 		return(EINVAL);
570 	if (mdio->md_options & MD_AUTOUNIT) {
571 		sc = mdnew(-1);
572 		if (sc == NULL)
573 			return (ENOMEM);
574 		mdio->md_unit = sc->unit;
575 	} else {
576 		sc = mdnew(mdio->md_unit);
577 		if (sc == NULL)
578 			return (EBUSY);
579 	}
580 	sc->type = MD_PRELOAD;
581 	sc->secsize = DEV_BSIZE;
582 	sc->nsect = mdio->md_size;
583 	sc->pl_ptr = (u_char *)mdio->md_base;
584 	sc->pl_len = (mdio->md_size << DEV_BSHIFT);
585 	mdinit(sc);
586 	return (0);
587 }
588 
589 
590 static int
591 mdcreate_malloc(struct md_ioctl *mdio)
592 {
593 	struct md_s *sc;
594 	unsigned u;
595 
596 	if (mdio->md_size == 0)
597 		return(EINVAL);
598 	if (mdio->md_options & ~(MD_AUTOUNIT | MD_COMPRESS | MD_RESERVE))
599 		return(EINVAL);
600 	/* Compression doesn't make sense if we have reserved space */
601 	if (mdio->md_options & MD_RESERVE)
602 		mdio->md_options &= ~MD_COMPRESS;
603 	if (mdio->md_options & MD_AUTOUNIT) {
604 		sc = mdnew(-1);
605 		if (sc == NULL)
606 			return (ENOMEM);
607 		mdio->md_unit = sc->unit;
608 	} else {
609 		sc = mdnew(mdio->md_unit);
610 		if (sc == NULL)
611 			return (EBUSY);
612 	}
613 	sc->type = MD_MALLOC;
614 	sc->secsize = DEV_BSIZE;
615 	sc->nsect = mdio->md_size;
616 	sc->flags = mdio->md_options & MD_COMPRESS;
617 	if (!(mdio->md_options & MD_RESERVE)) {
618 		MALLOC(sc->secp, u_char **, sizeof(u_char *), M_MD, M_WAITOK | M_ZERO);
619 		sc->nsecp = 1;
620 	} else {
621 		MALLOC(sc->secp, u_char **, sc->nsect * sizeof(u_char *), M_MD, M_WAITOK | M_ZERO);
622 		sc->nsecp = sc->nsect;
623 		for (u = 0; u < sc->nsect; u++)
624 			MALLOC(sc->secp[u], u_char *, DEV_BSIZE, M_MDSECT, M_WAITOK | M_ZERO);
625 	}
626 	printf("md%d: Malloc disk\n", sc->unit);
627 	mdinit(sc);
628 	return (0);
629 }
630 
631 
632 static int
633 mdsetcred(struct md_s *sc, struct ucred *cred)
634 {
635 	char *tmpbuf;
636 	int error = 0;
637 
638 	/*
639 	 * Set credits in our softc
640 	 */
641 
642 	if (sc->cred)
643 		crfree(sc->cred);
644 	sc->cred = crdup(cred);
645 
646 	/*
647 	 * Horrible kludge to establish credentials for NFS  XXX.
648 	 */
649 
650 	if (sc->vnode) {
651 		struct uio auio;
652 		struct iovec aiov;
653 
654 		tmpbuf = malloc(sc->secsize, M_TEMP, M_WAITOK);
655 		bzero(&auio, sizeof(auio));
656 
657 		aiov.iov_base = tmpbuf;
658 		aiov.iov_len = sc->secsize;
659 		auio.uio_iov = &aiov;
660 		auio.uio_iovcnt = 1;
661 		auio.uio_offset = 0;
662 		auio.uio_rw = UIO_READ;
663 		auio.uio_segflg = UIO_SYSSPACE;
664 		auio.uio_resid = aiov.iov_len;
665 		vn_lock(sc->vnode, LK_EXCLUSIVE | LK_RETRY, curproc);
666 		error = VOP_READ(sc->vnode, &auio, 0, sc->cred);
667 		VOP_UNLOCK(sc->vnode, 0, curproc);
668 		free(tmpbuf, M_TEMP);
669 	}
670 	return (error);
671 }
672 
673 static int
674 mdcreate_vnode(struct md_ioctl *mdio, struct proc *p)
675 {
676 	struct md_s *sc;
677 	struct vattr vattr;
678 	struct nameidata nd;
679 	int error, flags;
680 
681 	if (mdio->md_options & MD_AUTOUNIT) {
682 		sc = mdnew(-1);
683 		mdio->md_unit = sc->unit;
684 	} else {
685 		sc = mdnew(mdio->md_unit);
686 	}
687 	if (sc == NULL)
688 		return (EBUSY);
689 
690 	sc->type = MD_VNODE;
691 
692 	flags = FREAD|FWRITE;
693 	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, mdio->md_file, p);
694 	error = vn_open(&nd, &flags, 0);
695 	if (error) {
696 		if (error != EACCES && error != EPERM && error != EROFS)
697 			return (error);
698 		flags &= ~FWRITE;
699 		sc->flags |= MD_READONLY;
700 		NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, mdio->md_file, p);
701 		error = vn_open(&nd, &flags, 0);
702 		if (error)
703 			return (error);
704 	}
705 	NDFREE(&nd, NDF_ONLY_PNBUF);
706 	if (nd.ni_vp->v_type != VREG ||
707 	    (error = VOP_GETATTR(nd.ni_vp, &vattr, p->p_ucred, p))) {
708 		VOP_UNLOCK(nd.ni_vp, 0, p);
709 		(void) vn_close(nd.ni_vp, flags, p->p_ucred, p);
710 		return (error ? error : EINVAL);
711 	}
712 	VOP_UNLOCK(nd.ni_vp, 0, p);
713 	sc->secsize = DEV_BSIZE;
714 	sc->vnode = nd.ni_vp;
715 
716 	/*
717 	 * If the size is specified, override the file attributes.
718 	 */
719 	if (mdio->md_size)
720 		sc->nsect = mdio->md_size;
721 	else
722 		sc->nsect = vattr.va_size / sc->secsize; /* XXX: round up ? */
723 	error = mdsetcred(sc, p->p_ucred);
724 	if (error) {
725 		(void) vn_close(nd.ni_vp, flags, p->p_ucred, p);
726 		return(error);
727 	}
728 	mdinit(sc);
729 	return (0);
730 }
731 
732 static int
733 mddestroy(struct md_s *sc, struct md_ioctl *mdio, struct proc *p)
734 {
735 	unsigned u;
736 
737 	if (sc->dev != NULL)
738 		disk_destroy(sc->dev);
739 	if (sc->vnode != NULL)
740 		(void)vn_close(sc->vnode, sc->flags & MD_READONLY ?  FREAD : (FREAD|FWRITE), sc->cred, p);
741 	if (sc->cred != NULL)
742 		crfree(sc->cred);
743 	if (sc->object != NULL)
744 		vm_pager_deallocate(sc->object);
745 	if (sc->secp != NULL) {
746 		for (u = 0; u < sc->nsecp; u++)
747 			if ((uintptr_t)sc->secp[u] > 255)
748 				FREE(sc->secp[u], M_MDSECT);
749 		FREE(sc->secp, M_MD);
750 	}
751 	mddelete(sc);
752 	return (0);
753 }
754 
755 static int
756 mdcreate_swap(struct md_ioctl *mdio, struct proc *p)
757 {
758 	int error;
759 	struct md_s *sc;
760 
761 	if (mdio->md_options & MD_AUTOUNIT) {
762 		sc = mdnew(-1);
763 		mdio->md_unit = sc->unit;
764 	} else {
765 		sc = mdnew(mdio->md_unit);
766 	}
767 	if (sc == NULL)
768 		return (EBUSY);
769 
770 	sc->type = MD_SWAP;
771 
772 	/*
773 	 * Range check.  Disallow negative sizes or any size less then the
774 	 * size of a page.  Then round to a page.
775 	 */
776 
777 	if (mdio->md_size == 0)
778 		return(EDOM);
779 
780 	/*
781 	 * Allocate an OBJT_SWAP object.
782 	 *
783 	 * sc_secsize is PAGE_SIZE'd
784 	 *
785 	 * mdio->size is in DEV_BSIZE'd chunks.
786 	 * Note the truncation.
787 	 */
788 
789 	sc->secsize = PAGE_SIZE;
790 	sc->nsect = mdio->md_size / (PAGE_SIZE / DEV_BSIZE);
791 	sc->object = vm_pager_allocate(OBJT_SWAP, NULL, sc->secsize * (vm_offset_t)sc->nsect, VM_PROT_DEFAULT, 0);
792 	if (mdio->md_options & MD_RESERVE) {
793 		if (swap_pager_reserve(sc->object, 0, sc->nsect) < 0) {
794 			vm_pager_deallocate(sc->object);
795 			sc->object = NULL;
796 			return(EDOM);
797 		}
798 	}
799 	error = mdsetcred(sc, p->p_ucred);
800 	if (error)
801 		mddestroy(sc, mdio, p);
802 	else
803 		mdinit(sc);
804 	return(error);
805 }
806 
807 static int
808 mdctlioctl(dev_t dev, u_long cmd, caddr_t addr, int flags, struct proc *p)
809 {
810 	struct md_ioctl *mdio;
811 	struct md_s *sc;
812 
813 	if (md_debug)
814 		printf("mdctlioctl(%s %lx %p %x %p)\n",
815 			devtoname(dev), cmd, addr, flags, p);
816 
817 	mdio = (struct md_ioctl *)addr;
818 	switch (cmd) {
819 	case MDIOCATTACH:
820 		switch (mdio->md_type) {
821 		case MD_MALLOC:
822 			return(mdcreate_malloc(mdio));
823 		case MD_PRELOAD:
824 			return(mdcreate_preload(mdio));
825 		case MD_VNODE:
826 			return(mdcreate_vnode(mdio, p));
827 		case MD_SWAP:
828 			return(mdcreate_swap(mdio, p));
829 		default:
830 			return (EINVAL);
831 		}
832 	case MDIOCDETACH:
833 		if (mdio->md_file != NULL)
834 			return(EINVAL);
835 		if (mdio->md_size != 0)
836 			return(EINVAL);
837 		if (mdio->md_options != 0)
838 			return(EINVAL);
839 		sc = mdfind(mdio->md_unit);
840 		if (sc == NULL)
841 			return (ENOENT);
842 		switch(sc->type) {
843 		case MD_VNODE:
844 		case MD_SWAP:
845 		case MD_MALLOC:
846 		case MD_PRELOAD:
847 			return(mddestroy(sc, mdio, p));
848 		default:
849 			return (EOPNOTSUPP);
850 		}
851 	default:
852 		return (ENOIOCTL);
853 	};
854 	return (ENOIOCTL);
855 }
856 
857 static void
858 md_preloaded(u_char *image, unsigned length)
859 {
860 	struct md_s *sc;
861 
862 	sc = mdnew(-1);
863 	if (sc == NULL)
864 		return;
865 	sc->type = MD_PRELOAD;
866 	sc->secsize = DEV_BSIZE;
867 	sc->nsect = length / DEV_BSIZE;
868 	sc->pl_ptr = image;
869 	sc->pl_len = length;
870 	if (sc->unit == 0)
871 		mdrootready = 1;
872 	mdinit(sc);
873 }
874 
875 static void
876 md_drvinit(void *unused)
877 {
878 
879 	caddr_t mod;
880 	caddr_t c;
881 	u_char *ptr, *name, *type;
882 	unsigned len;
883 
884 #ifdef MD_ROOT_SIZE
885 	md_preloaded(mfs_root, MD_ROOT_SIZE*1024);
886 #endif
887 	mod = NULL;
888 	while ((mod = preload_search_next_name(mod)) != NULL) {
889 		name = (char *)preload_search_info(mod, MODINFO_NAME);
890 		type = (char *)preload_search_info(mod, MODINFO_TYPE);
891 		if (name == NULL)
892 			continue;
893 		if (type == NULL)
894 			continue;
895 		if (strcmp(type, "md_image") && strcmp(type, "mfs_root"))
896 			continue;
897 		c = preload_search_info(mod, MODINFO_ADDR);
898 		ptr = *(u_char **)c;
899 		c = preload_search_info(mod, MODINFO_SIZE);
900 		len = *(unsigned *)c;
901 		printf("md%d: Preloaded image <%s> %d bytes at %p\n",
902 		   mdunits, name, len, ptr);
903 		md_preloaded(ptr, len);
904 	}
905 	make_dev(&mdctl_cdevsw, 0xffff00ff, UID_ROOT, GID_WHEEL, 0600, "mdctl");
906 }
907 
908 SYSINIT(mddev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR, md_drvinit,NULL)
909 
910 #ifdef MD_ROOT
911 static void
912 md_takeroot(void *junk)
913 {
914 	if (mdrootready)
915 		rootdevnames[0] = "ufs:/dev/md0c";
916 }
917 
918 SYSINIT(md_root, SI_SUB_MOUNT_ROOT, SI_ORDER_FIRST, md_takeroot, NULL);
919 #endif
920 
921