xref: /dragonfly/sys/kern/subr_disk.c (revision 2e3ed54d)
1 /*
2  * Copyright (c) 2003,2004 The DragonFly Project.  All rights reserved.
3  *
4  * This code is derived from software contributed to The DragonFly Project
5  * by Matthew Dillon <dillon@backplane.com>
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  *
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in
15  *    the documentation and/or other materials provided with the
16  *    distribution.
17  * 3. Neither the name of The DragonFly Project nor the names of its
18  *    contributors may be used to endorse or promote products derived
19  *    from this software without specific, prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  *
34  * ----------------------------------------------------------------------------
35  * "THE BEER-WARE LICENSE" (Revision 42):
36  * <phk@FreeBSD.ORG> wrote this file.  As long as you retain this notice you
37  * can do whatever you want with this stuff. If we meet some day, and you think
38  * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
39  * ----------------------------------------------------------------------------
40  *
41  * Copyright (c) 1982, 1986, 1988, 1993
42  *	The Regents of the University of California.  All rights reserved.
43  * (c) UNIX System Laboratories, Inc.
44  * All or some portions of this file are derived from material licensed
45  * to the University of California by American Telephone and Telegraph
46  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
47  * the permission of UNIX System Laboratories, Inc.
48  *
49  * Redistribution and use in source and binary forms, with or without
50  * modification, are permitted provided that the following conditions
51  * are met:
52  * 1. Redistributions of source code must retain the above copyright
53  *    notice, this list of conditions and the following disclaimer.
54  * 2. Redistributions in binary form must reproduce the above copyright
55  *    notice, this list of conditions and the following disclaimer in the
56  *    documentation and/or other materials provided with the distribution.
57  * 3. All advertising materials mentioning features or use of this software
58  *    must display the following acknowledgement:
59  *	This product includes software developed by the University of
60  *	California, Berkeley and its contributors.
61  * 4. Neither the name of the University nor the names of its contributors
62  *    may be used to endorse or promote products derived from this software
63  *    without specific prior written permission.
64  *
65  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
66  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
67  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
68  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
69  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
70  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
71  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
72  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
73  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
74  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
75  * SUCH DAMAGE.
76  *
77  *	@(#)ufs_disksubr.c	8.5 (Berkeley) 1/21/94
78  * $FreeBSD: src/sys/kern/subr_disk.c,v 1.20.2.6 2001/10/05 07:14:57 peter Exp $
79  * $FreeBSD: src/sys/ufs/ufs/ufs_disksubr.c,v 1.44.2.3 2001/03/05 05:42:19 obrien Exp $
80  * $DragonFly: src/sys/kern/subr_disk.c,v 1.20 2005/09/10 21:01:20 swildner Exp $
81  */
82 
83 #include <sys/param.h>
84 #include <sys/systm.h>
85 #include <sys/kernel.h>
86 #include <sys/proc.h>
87 #include <sys/sysctl.h>
88 #include <sys/buf.h>
89 #include <sys/conf.h>
90 #include <sys/disklabel.h>
91 #include <sys/diskslice.h>
92 #include <sys/disk.h>
93 #include <sys/malloc.h>
94 #include <sys/sysctl.h>
95 #include <machine/md_var.h>
96 #include <sys/ctype.h>
97 #include <sys/syslog.h>
98 #include <sys/device.h>
99 #include <sys/msgport.h>
100 #include <sys/msgport2.h>
101 #include <sys/buf2.h>
102 
103 static MALLOC_DEFINE(M_DISK, "disk", "disk data");
104 
105 static d_strategy_t diskstrategy;
106 static d_open_t diskopen;
107 static d_close_t diskclose;
108 static d_ioctl_t diskioctl;
109 static d_psize_t diskpsize;
110 static d_clone_t diskclone;
111 static int disk_putport(lwkt_port_t port, lwkt_msg_t msg);
112 
113 static LIST_HEAD(, disk) disklist = LIST_HEAD_INITIALIZER(&disklist);
114 
115 /*
116  * Create a slice and unit managed disk.
117  *
118  * Our port layer will be responsible for assigning pblkno and handling
119  * high level partition operations, then forwarding the requests to the
120  * raw device.
121  *
122  * The disk_create() function clones the provided rawsw for creating a
123  * managed disk device.  In addition, the cdevsw intercept port is
124  * changed to disk_putport, which is used to transform requests for the
125  * managed disk device.
126  *
127  * The raw device (based on rawsw) is returned to the caller, NOT the
128  * slice and unit managed cdev.  The caller typically sets various
129  * driver parameters and IO limits on the returned rawdev which we must
130  * inherit when our managed device is opened.
131  */
132 dev_t
133 disk_create(int unit, struct disk *dp, int flags, struct cdevsw *rawsw)
134 {
135 	dev_t rawdev;
136 	struct cdevsw *devsw;
137 
138 	/*
139 	 * Create the raw backing device
140 	 */
141 	compile_devsw(rawsw);
142 	rawdev = make_dev(rawsw, dkmakeminor(unit, WHOLE_DISK_SLICE, RAW_PART),
143 			    UID_ROOT, GID_OPERATOR, 0640,
144 			    "%s%d", rawsw->d_name, unit);
145 
146 	/*
147 	 * Initialize our intercept port
148 	 */
149 	bzero(dp, sizeof(*dp));
150 	lwkt_initport(&dp->d_port, NULL);
151 	dp->d_port.mp_putport = disk_putport;
152 	dp->d_rawsw = rawsw;
153 
154 	/*
155 	 * We install a custom cdevsw rather then the passed cdevsw,
156 	 * and save our disk structure in d_data so we can get at it easily
157 	 * without any complex cloning code.
158 	 */
159 	devsw = cdevsw_add_override(rawdev, dkunitmask(), dkmakeunit(unit));
160 	devsw->d_port = &dp->d_port;
161 	devsw->d_data = dp;
162 	devsw->d_clone = diskclone;
163 	dp->d_devsw = devsw;
164 	dp->d_rawdev = rawdev;
165 	dp->d_cdev = make_dev(devsw,
166 			    dkmakeminor(unit, WHOLE_DISK_SLICE, RAW_PART),
167 			    UID_ROOT, GID_OPERATOR, 0640,
168 			    "%s%d", devsw->d_name, unit);
169 
170 	dp->d_dsflags = flags;
171 	LIST_INSERT_HEAD(&disklist, dp, d_list);
172 	return (dp->d_rawdev);
173 }
174 
175 /*
176  * This routine is called when an adapter detaches.  The higher level
177  * managed disk device is destroyed while the lower level raw device is
178  * released.
179  */
180 void
181 disk_destroy(struct disk *disk)
182 {
183 	if (disk->d_devsw) {
184 	    cdevsw_remove(disk->d_devsw, dkunitmask(),
185 			    dkmakeunit(dkunit(disk->d_cdev)));
186 	    LIST_REMOVE(disk, d_list);
187 	}
188 	if (disk->d_rawsw) {
189 	    destroy_all_dev(disk->d_rawsw, dkunitmask(),
190 			    dkmakeunit(dkunit(disk->d_rawdev)));
191 	}
192 	bzero(disk, sizeof(*disk));
193 }
194 
195 int
196 disk_dumpcheck(dev_t dev, u_int *count, u_int *blkno, u_int *secsize)
197 {
198 	struct disk *dp;
199 	struct disklabel *dl;
200 	u_int boff;
201 
202 	dp = dev->si_disk;
203 	if (!dp)
204 		return (ENXIO);
205 	if (!dp->d_slice)
206 		return (ENXIO);
207 	dl = dsgetlabel(dev, dp->d_slice);
208 	if (!dl)
209 		return (ENXIO);
210 	*count = Maxmem * (PAGE_SIZE / dl->d_secsize);
211 	if (dumplo <= LABELSECTOR ||
212 	    (dumplo + *count > dl->d_partitions[dkpart(dev)].p_size))
213 		return (EINVAL);
214 	boff = dl->d_partitions[dkpart(dev)].p_offset +
215 	    dp->d_slice->dss_slices[dkslice(dev)].ds_offset;
216 	*blkno = boff + dumplo;
217 	*secsize = dl->d_secsize;
218 	return (0);
219 
220 }
221 
222 void
223 disk_invalidate (struct disk *disk)
224 {
225 	if (disk->d_slice)
226 		dsgone(&disk->d_slice);
227 }
228 
229 struct disk *
230 disk_enumerate(struct disk *disk)
231 {
232 	if (!disk)
233 		return (LIST_FIRST(&disklist));
234 	else
235 		return (LIST_NEXT(disk, d_list));
236 }
237 
238 static
239 int
240 sysctl_disks(SYSCTL_HANDLER_ARGS)
241 {
242 	struct disk *disk;
243 	int error, first;
244 
245 	disk = NULL;
246 	first = 1;
247 
248 	while ((disk = disk_enumerate(disk))) {
249 		if (!first) {
250 			error = SYSCTL_OUT(req, " ", 1);
251 			if (error)
252 				return error;
253 		} else {
254 			first = 0;
255 		}
256 		error = SYSCTL_OUT(req, disk->d_rawdev->si_name,
257 				   strlen(disk->d_rawdev->si_name));
258 		if (error)
259 			return error;
260 	}
261 	error = SYSCTL_OUT(req, "", 1);
262 	return error;
263 }
264 
265 SYSCTL_PROC(_kern, OID_AUTO, disks, CTLTYPE_STRING | CTLFLAG_RD, 0, NULL,
266     sysctl_disks, "A", "names of available disks");
267 
268 /*
269  * The port intercept functions
270  */
271 static
272 int
273 disk_putport(lwkt_port_t port, lwkt_msg_t lmsg)
274 {
275 	struct disk *disk = (struct disk *)port;
276 	cdevallmsg_t msg = (cdevallmsg_t)lmsg;
277 	int error;
278 
279 	switch(msg->am_lmsg.ms_cmd.cm_op) {
280 	case CDEV_CMD_OPEN:
281 		error = diskopen(
282 			    msg->am_open.msg.dev,
283 			    msg->am_open.oflags,
284 			    msg->am_open.devtype,
285 			    msg->am_open.td);
286 		break;
287 	case CDEV_CMD_CLOSE:
288 		error = diskclose(
289 			    msg->am_close.msg.dev,
290 			    msg->am_close.fflag,
291 			    msg->am_close.devtype,
292 			    msg->am_close.td);
293 		break;
294 	case CDEV_CMD_IOCTL:
295 		error = diskioctl(
296 			    msg->am_ioctl.msg.dev,
297 			    msg->am_ioctl.cmd,
298 			    msg->am_ioctl.data,
299 			    msg->am_ioctl.fflag,
300 			    msg->am_ioctl.td);
301 		break;
302 	case CDEV_CMD_STRATEGY:
303 		diskstrategy(msg->am_strategy.bp);
304 		error = 0;
305 		break;
306 	case CDEV_CMD_PSIZE:
307 		msg->am_psize.result = diskpsize(msg->am_psize.msg.dev);
308 		error = 0;      /* XXX */
309 		break;
310 	case CDEV_CMD_READ:
311 		error = physio(msg->am_read.msg.dev,
312 				msg->am_read.uio, msg->am_read.ioflag);
313 		break;
314 	case CDEV_CMD_WRITE:
315 		error = physio(msg->am_write.msg.dev,
316 				msg->am_write.uio, msg->am_write.ioflag);
317 		break;
318 	case CDEV_CMD_POLL:
319 	case CDEV_CMD_KQFILTER:
320 		error = ENODEV;
321 	case CDEV_CMD_MMAP:
322 		error = -1;
323 		break;
324 	case CDEV_CMD_DUMP:
325 		error = disk_dumpcheck(msg->am_dump.msg.dev,
326 				&msg->am_dump.count,
327 				&msg->am_dump.blkno,
328 				&msg->am_dump.secsize);
329 		if (error == 0) {
330 			msg->am_dump.msg.dev = disk->d_rawdev;
331 			error = lwkt_forwardmsg(disk->d_rawdev->si_port,
332 						&msg->am_dump.msg.msg);
333 			printf("error2 %d\n", error);
334 		}
335 		break;
336 	default:
337 		error = ENOTSUP;
338 		break;
339 	}
340 	return(error);
341 }
342 
343 /*
344  * When new device entries are instantiated, make sure they inherit our
345  * si_disk structure and block and iosize limits from the raw device.
346  *
347  * This routine is always called synchronously in the context of the
348  * client.
349  *
350  * XXX The various io and block size constraints are not always initialized
351  * properly by devices.
352  */
353 static
354 int
355 diskclone(dev_t dev)
356 {
357 	struct disk *dp;
358 
359 	dp = dev->si_devsw->d_data;
360 	KKASSERT(dp != NULL);
361 	dev->si_disk = dp;
362 	dev->si_iosize_max = dp->d_rawdev->si_iosize_max;
363 	dev->si_bsize_phys = dp->d_rawdev->si_bsize_phys;
364 	dev->si_bsize_best = dp->d_rawdev->si_bsize_best;
365 	return(0);
366 }
367 
368 /*
369  * Open a disk device or partition.
370  */
371 static
372 int
373 diskopen(dev_t dev, int oflags, int devtype, struct thread *td)
374 {
375 	struct disk *dp;
376 	int error;
377 
378 	/*
379 	 * dp can't be NULL here XXX.
380 	 */
381 	error = 0;
382 	dp = dev->si_disk;
383 	if (dp == NULL)
384 		return (ENXIO);
385 
386 	/*
387 	 * Deal with open races
388 	 */
389 	while (dp->d_flags & DISKFLAG_LOCK) {
390 		dp->d_flags |= DISKFLAG_WANTED;
391 		error = tsleep(dp, PCATCH, "diskopen", hz);
392 		if (error)
393 			return (error);
394 	}
395 	dp->d_flags |= DISKFLAG_LOCK;
396 
397 	/*
398 	 * Open the underlying raw device.
399 	 */
400 	if (!dsisopen(dp->d_slice)) {
401 #if 0
402 		if (!pdev->si_iosize_max)
403 			pdev->si_iosize_max = dev->si_iosize_max;
404 #endif
405 		error = dev_dopen(dp->d_rawdev, oflags, devtype, td);
406 	}
407 
408 	/*
409 	 * Inherit properties from the underlying device now that it is
410 	 * open.
411 	 */
412 	diskclone(dev);
413 
414 	if (error)
415 		goto out;
416 
417 	error = dsopen(dev, devtype, dp->d_dsflags, &dp->d_slice, &dp->d_label);
418 
419 	if (!dsisopen(dp->d_slice))
420 		dev_dclose(dp->d_rawdev, oflags, devtype, td);
421 out:
422 	dp->d_flags &= ~DISKFLAG_LOCK;
423 	if (dp->d_flags & DISKFLAG_WANTED) {
424 		dp->d_flags &= ~DISKFLAG_WANTED;
425 		wakeup(dp);
426 	}
427 
428 	return(error);
429 }
430 
431 /*
432  * Close a disk device or partition
433  */
434 static
435 int
436 diskclose(dev_t dev, int fflag, int devtype, struct thread *td)
437 {
438 	struct disk *dp;
439 	int error;
440 
441 	error = 0;
442 	dp = dev->si_disk;
443 
444 	dsclose(dev, devtype, dp->d_slice);
445 	if (!dsisopen(dp->d_slice))
446 		error = dev_dclose(dp->d_rawdev, fflag, devtype, td);
447 	return (error);
448 }
449 
450 /*
451  * Execute strategy routine
452  */
453 static
454 void
455 diskstrategy(struct buf *bp)
456 {
457 	struct disk *dp;
458 
459 	dp = bp->b_dev->si_disk;
460 
461 	if (dp == NULL) {
462 		bp->b_error = ENXIO;
463 		bp->b_flags |= B_ERROR;
464 		biodone(bp);
465 		return;
466 	}
467 	KKASSERT(bp->b_dev->si_disk == dp);
468 
469 	/*
470 	 * The dscheck() function will also transform the slice relative
471 	 * block number i.e. bp->b_blkno into a block number that can be
472 	 * passed directly to the underlying raw device.
473 	 */
474 	if (dscheck(bp, dp->d_slice) <= 0) {
475 		biodone(bp);
476 		return;
477 	}
478 	bp->b_dev = dp->d_rawdev;
479 	dev_dstrategy(dp->d_rawdev, bp);
480 }
481 
482 /*
483  * First execute the ioctl on the disk device, and if it isn't supported
484  * try running it on the backing device.
485  */
486 static
487 int
488 diskioctl(dev_t dev, u_long cmd, caddr_t data, int fflag, struct thread *td)
489 {
490 	struct disk *dp;
491 	int error;
492 
493 	dp = dev->si_disk;
494 	if (dp == NULL)
495 		return (ENXIO);
496 
497 	error = dsioctl(dev, cmd, data, fflag, &dp->d_slice);
498 	if (error == ENOIOCTL)
499 		error = dev_dioctl(dp->d_rawdev, cmd, data, fflag, td);
500 	return (error);
501 }
502 
503 /*
504  *
505  */
506 static
507 int
508 diskpsize(dev_t dev)
509 {
510 	struct disk *dp;
511 
512 	dp = dev->si_disk;
513 	if (dp == NULL)
514 		return (-1);
515 	return(dssize(dev, &dp->d_slice));
516 #if 0
517 	if (dp != dev->si_disk) {
518 		dev->si_drv1 = pdev->si_drv1;
519 		dev->si_drv2 = pdev->si_drv2;
520 		/* XXX: don't set bp->b_dev->si_disk (?) */
521 	}
522 #endif
523 }
524 
525 SYSCTL_INT(_debug_sizeof, OID_AUTO, disklabel, CTLFLAG_RD,
526     0, sizeof(struct disklabel), "sizeof(struct disklabel)");
527 
528 SYSCTL_INT(_debug_sizeof, OID_AUTO, diskslices, CTLFLAG_RD,
529     0, sizeof(struct diskslices), "sizeof(struct diskslices)");
530 
531 SYSCTL_INT(_debug_sizeof, OID_AUTO, disk, CTLFLAG_RD,
532     0, sizeof(struct disk), "sizeof(struct disk)");
533 
534 
535 /*
536  * Seek sort for disks.
537  *
538  * The buf_queue keep two queues, sorted in ascending block order.  The first
539  * queue holds those requests which are positioned after the current block
540  * (in the first request); the second, which starts at queue->switch_point,
541  * holds requests which came in after their block number was passed.  Thus
542  * we implement a one way scan, retracting after reaching the end of the drive
543  * to the first request on the second queue, at which time it becomes the
544  * first queue.
545  *
546  * A one-way scan is natural because of the way UNIX read-ahead blocks are
547  * allocated.
548  */
549 void
550 bufqdisksort(struct buf_queue_head *bufq, struct buf *bp)
551 {
552 	struct buf *bq;
553 	struct buf *bn;
554 	struct buf *be;
555 
556 	be = TAILQ_LAST(&bufq->queue, buf_queue);
557 	/*
558 	 * If the queue is empty or we are an
559 	 * ordered transaction, then it's easy.
560 	 */
561 	if ((bq = bufq_first(bufq)) == NULL ||
562 	    (bp->b_flags & B_ORDERED) != 0) {
563 		bufq_insert_tail(bufq, bp);
564 		return;
565 	} else if (bufq->insert_point != NULL) {
566 
567 		/*
568 		 * A certain portion of the list is
569 		 * "locked" to preserve ordering, so
570 		 * we can only insert after the insert
571 		 * point.
572 		 */
573 		bq = bufq->insert_point;
574 	} else {
575 
576 		/*
577 		 * If we lie before the last removed (currently active)
578 		 * request, and are not inserting ourselves into the
579 		 * "locked" portion of the list, then we must add ourselves
580 		 * to the second request list.
581 		 */
582 		if (bp->b_pblkno < bufq->last_pblkno) {
583 
584 			bq = bufq->switch_point;
585 			/*
586 			 * If we are starting a new secondary list,
587 			 * then it's easy.
588 			 */
589 			if (bq == NULL) {
590 				bufq->switch_point = bp;
591 				bufq_insert_tail(bufq, bp);
592 				return;
593 			}
594 			/*
595 			 * If we lie ahead of the current switch point,
596 			 * insert us before the switch point and move
597 			 * the switch point.
598 			 */
599 			if (bp->b_pblkno < bq->b_pblkno) {
600 				bufq->switch_point = bp;
601 				TAILQ_INSERT_BEFORE(bq, bp, b_act);
602 				return;
603 			}
604 		} else {
605 			if (bufq->switch_point != NULL)
606 				be = TAILQ_PREV(bufq->switch_point,
607 						buf_queue, b_act);
608 			/*
609 			 * If we lie between last_pblkno and bq,
610 			 * insert before bq.
611 			 */
612 			if (bp->b_pblkno < bq->b_pblkno) {
613 				TAILQ_INSERT_BEFORE(bq, bp, b_act);
614 				return;
615 			}
616 		}
617 	}
618 
619 	/*
620 	 * Request is at/after our current position in the list.
621 	 * Optimize for sequential I/O by seeing if we go at the tail.
622 	 */
623 	if (bp->b_pblkno > be->b_pblkno) {
624 		TAILQ_INSERT_AFTER(&bufq->queue, be, bp, b_act);
625 		return;
626 	}
627 
628 	/* Otherwise, insertion sort */
629 	while ((bn = TAILQ_NEXT(bq, b_act)) != NULL) {
630 
631 		/*
632 		 * We want to go after the current request if it is the end
633 		 * of the first request list, or if the next request is a
634 		 * larger cylinder than our request.
635 		 */
636 		if (bn == bufq->switch_point
637 		 || bp->b_pblkno < bn->b_pblkno)
638 			break;
639 		bq = bn;
640 	}
641 	TAILQ_INSERT_AFTER(&bufq->queue, bq, bp, b_act);
642 }
643 
644 
645 /*
646  * Attempt to read a disk label from a device using the indicated strategy
647  * routine.  The label must be partly set up before this: secpercyl, secsize
648  * and anything required in the strategy routine (e.g., dummy bounds for the
649  * partition containing the label) must be filled in before calling us.
650  * Returns NULL on success and an error string on failure.
651  */
652 char *
653 readdisklabel(dev_t dev, struct disklabel *lp)
654 {
655 	struct buf *bp;
656 	struct disklabel *dlp;
657 	char *msg = NULL;
658 
659 	bp = geteblk((int)lp->d_secsize);
660 	bp->b_dev = dev;
661 	bp->b_blkno = LABELSECTOR * ((int)lp->d_secsize/DEV_BSIZE);
662 	bp->b_bcount = lp->d_secsize;
663 	bp->b_flags &= ~B_INVAL;
664 	bp->b_flags |= B_READ;
665 	BUF_STRATEGY(bp, 1);
666 	if (biowait(bp))
667 		msg = "I/O error";
668 	else for (dlp = (struct disklabel *)bp->b_data;
669 	    dlp <= (struct disklabel *)((char *)bp->b_data +
670 	    lp->d_secsize - sizeof(*dlp));
671 	    dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
672 		if (dlp->d_magic != DISKMAGIC || dlp->d_magic2 != DISKMAGIC) {
673 			if (msg == NULL)
674 				msg = "no disk label";
675 		} else if (dlp->d_npartitions > MAXPARTITIONS ||
676 			   dkcksum(dlp) != 0)
677 			msg = "disk label corrupted";
678 		else {
679 			*lp = *dlp;
680 			msg = NULL;
681 			break;
682 		}
683 	}
684 	bp->b_flags |= B_INVAL | B_AGE;
685 	brelse(bp);
686 	return (msg);
687 }
688 
689 /*
690  * Check new disk label for sensibility before setting it.
691  */
692 int
693 setdisklabel(struct disklabel *olp, struct disklabel *nlp, u_long openmask)
694 {
695 	int i;
696 	struct partition *opp, *npp;
697 
698 	/*
699 	 * Check it is actually a disklabel we are looking at.
700 	 */
701 	if (nlp->d_magic != DISKMAGIC || nlp->d_magic2 != DISKMAGIC ||
702 	    dkcksum(nlp) != 0)
703 		return (EINVAL);
704 	/*
705 	 * For each partition that we think is open,
706 	 */
707 	while ((i = ffs((long)openmask)) != 0) {
708 		i--;
709 		/*
710 	 	 * Check it is not changing....
711 	 	 */
712 		openmask &= ~(1 << i);
713 		if (nlp->d_npartitions <= i)
714 			return (EBUSY);
715 		opp = &olp->d_partitions[i];
716 		npp = &nlp->d_partitions[i];
717 		if (npp->p_offset != opp->p_offset || npp->p_size < opp->p_size)
718 			return (EBUSY);
719 		/*
720 		 * Copy internally-set partition information
721 		 * if new label doesn't include it.		XXX
722 		 * (If we are using it then we had better stay the same type)
723 		 * This is possibly dubious, as someone else noted (XXX)
724 		 */
725 		if (npp->p_fstype == FS_UNUSED && opp->p_fstype != FS_UNUSED) {
726 			npp->p_fstype = opp->p_fstype;
727 			npp->p_fsize = opp->p_fsize;
728 			npp->p_frag = opp->p_frag;
729 			npp->p_cpg = opp->p_cpg;
730 		}
731 	}
732  	nlp->d_checksum = 0;
733  	nlp->d_checksum = dkcksum(nlp);
734 	*olp = *nlp;
735 	return (0);
736 }
737 
738 /*
739  * Write disk label back to device after modification.
740  */
741 int
742 writedisklabel(dev_t dev, struct disklabel *lp)
743 {
744 	struct buf *bp;
745 	struct disklabel *dlp;
746 	int error = 0;
747 
748 	if (lp->d_partitions[RAW_PART].p_offset != 0)
749 		return (EXDEV);			/* not quite right */
750 	bp = geteblk((int)lp->d_secsize);
751 	bp->b_dev = dkmodpart(dev, RAW_PART);
752 	bp->b_blkno = LABELSECTOR * ((int)lp->d_secsize/DEV_BSIZE);
753 	bp->b_bcount = lp->d_secsize;
754 #if 1
755 	/*
756 	 * We read the label first to see if it's there,
757 	 * in which case we will put ours at the same offset into the block..
758 	 * (I think this is stupid [Julian])
759 	 * Note that you can't write a label out over a corrupted label!
760 	 * (also stupid.. how do you write the first one? by raw writes?)
761 	 */
762 	bp->b_flags &= ~B_INVAL;
763 	bp->b_flags |= B_READ;
764 	BUF_STRATEGY(bp, 1);
765 	error = biowait(bp);
766 	if (error)
767 		goto done;
768 	for (dlp = (struct disklabel *)bp->b_data;
769 	    dlp <= (struct disklabel *)
770 	      ((char *)bp->b_data + lp->d_secsize - sizeof(*dlp));
771 	    dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
772 		if (dlp->d_magic == DISKMAGIC && dlp->d_magic2 == DISKMAGIC &&
773 		    dkcksum(dlp) == 0) {
774 			*dlp = *lp;
775 			bp->b_flags &= ~(B_DONE | B_READ);
776 			bp->b_flags |= B_WRITE;
777 			bp->b_dev = dkmodpart(dev, RAW_PART);
778 			BUF_STRATEGY(bp, 1);
779 			error = biowait(bp);
780 			goto done;
781 		}
782 	}
783 	error = ESRCH;
784 done:
785 #else
786 	bzero(bp->b_data, lp->d_secsize);
787 	dlp = (struct disklabel *)bp->b_data;
788 	*dlp = *lp;
789 	bp->b_flags &= ~B_INVAL;
790 	bp->b_flags |= B_WRITE;
791 	BUF_STRATEGY(bp, 1);
792 	error = biowait(bp);
793 #endif
794 	bp->b_flags |= B_INVAL | B_AGE;
795 	brelse(bp);
796 	return (error);
797 }
798 
799 /*
800  * Disk error is the preface to plaintive error messages
801  * about failing disk transfers.  It prints messages of the form
802 
803 hp0g: hard error reading fsbn 12345 of 12344-12347 (hp0 bn %d cn %d tn %d sn %d)
804 
805  * if the offset of the error in the transfer and a disk label
806  * are both available.  blkdone should be -1 if the position of the error
807  * is unknown; the disklabel pointer may be null from drivers that have not
808  * been converted to use them.  The message is printed with printf
809  * if pri is LOG_PRINTF, otherwise it uses log at the specified priority.
810  * The message should be completed (with at least a newline) with printf
811  * or addlog, respectively.  There is no trailing space.
812  */
813 void
814 diskerr(struct buf *bp, dev_t dev, char *what, int pri,
815 	int blkdone, struct disklabel *lp)
816 {
817 	int unit = dkunit(dev);
818 	int slice = dkslice(dev);
819 	int part = dkpart(dev);
820 	char partname[2];
821 	char *sname;
822 	daddr_t sn;
823 
824 	sname = dsname(dev, unit, slice, part, partname);
825 	printf("%s%s: %s %sing fsbn ", sname, partname, what,
826 	      bp->b_flags & B_READ ? "read" : "writ");
827 	sn = bp->b_blkno;
828 	if (bp->b_bcount <= DEV_BSIZE) {
829 		printf("%ld", (long)sn);
830 	} else {
831 		if (blkdone >= 0) {
832 			sn += blkdone;
833 			printf("%ld of ", (long)sn);
834 		}
835 		printf("%ld-%ld", (long)bp->b_blkno,
836 		    (long)(bp->b_blkno + (bp->b_bcount - 1) / DEV_BSIZE));
837 	}
838 	if (lp && (blkdone >= 0 || bp->b_bcount <= lp->d_secsize)) {
839 		sn += lp->d_partitions[part].p_offset;
840 		/*
841 		 * XXX should add slice offset and not print the slice,
842 		 * but we don't know the slice pointer.
843 		 * XXX should print bp->b_pblkno so that this will work
844 		 * independent of slices, labels and bad sector remapping,
845 		 * but some drivers don't set bp->b_pblkno.
846 		 */
847 		printf(" (%s bn %ld; cn %ld", sname, (long)sn,
848 		    (long)(sn / lp->d_secpercyl));
849 		sn %= (long)lp->d_secpercyl;
850 		printf(" tn %ld sn %ld)", (long)(sn / lp->d_nsectors),
851 		    (long)(sn % lp->d_nsectors));
852 	}
853 }
854