xref: /illumos-gate/usr/src/uts/common/fs/zfs/zvol.c (revision 5328fc53d11d7151861fa272e4fb0248b8f0e145)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23  *
24  * Portions Copyright 2010 Robert Milkowski
25  *
26  * Copyright 2017 Nexenta Systems, Inc.  All rights reserved.
27  * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
28  * Copyright (c) 2014 Integros [integros.com]
29  * Copyright 2019 Joyent, Inc.
30  */
31 
32 /*
33  * ZFS volume emulation driver.
34  *
35  * Makes a DMU object look like a volume of arbitrary size, up to 2^64 bytes.
36  * Volumes are accessed through the symbolic links named:
37  *
38  * /dev/zvol/dsk/<pool_name>/<dataset_name>
39  * /dev/zvol/rdsk/<pool_name>/<dataset_name>
40  *
41  * These links are created by the /dev filesystem (sdev_zvolops.c).
42  * Volumes are persistent through reboot.  No user command needs to be
43  * run before opening and using a device.
44  */
45 
46 #include <sys/types.h>
47 #include <sys/param.h>
48 #include <sys/errno.h>
49 #include <sys/uio.h>
50 #include <sys/buf.h>
51 #include <sys/modctl.h>
52 #include <sys/open.h>
53 #include <sys/kmem.h>
54 #include <sys/conf.h>
55 #include <sys/cmn_err.h>
56 #include <sys/stat.h>
57 #include <sys/zap.h>
58 #include <sys/spa.h>
59 #include <sys/spa_impl.h>
60 #include <sys/zio.h>
61 #include <sys/dmu_traverse.h>
62 #include <sys/dnode.h>
63 #include <sys/dsl_dataset.h>
64 #include <sys/dsl_prop.h>
65 #include <sys/dkio.h>
66 #include <sys/efi_partition.h>
67 #include <sys/byteorder.h>
68 #include <sys/pathname.h>
69 #include <sys/ddi.h>
70 #include <sys/sunddi.h>
71 #include <sys/crc32.h>
72 #include <sys/dirent.h>
73 #include <sys/policy.h>
74 #include <sys/fs/zfs.h>
75 #include <sys/zfs_ioctl.h>
76 #include <sys/mkdev.h>
77 #include <sys/zil.h>
78 #include <sys/refcount.h>
79 #include <sys/zfs_znode.h>
80 #include <sys/zfs_rlock.h>
81 #include <sys/vdev_disk.h>
82 #include <sys/vdev_impl.h>
83 #include <sys/vdev_raidz.h>
84 #include <sys/zvol.h>
85 #include <sys/dumphdr.h>
86 #include <sys/zil_impl.h>
87 #include <sys/dbuf.h>
88 #include <sys/dmu_tx.h>
89 #include <sys/zfeature.h>
90 #include <sys/zio_checksum.h>
91 #include <sys/zil_impl.h>
92 #include <sys/smt.h>
93 #include <sys/dkioc_free_util.h>
94 #include <sys/zfs_rlock.h>
95 
96 #include "zfs_namecheck.h"
97 
98 void *zfsdev_state;
99 static char *zvol_tag = "zvol_tag";
100 
101 #define	ZVOL_DUMPSIZE		"dumpsize"
102 
103 /*
104  * This lock protects the zfsdev_state structure from being modified
105  * while it's being used, e.g. an open that comes in before a create
106  * finishes.  It also protects temporary opens of the dataset so that,
107  * e.g., an open doesn't get a spurious EBUSY.
108  */
109 kmutex_t zfsdev_state_lock;
110 static uint32_t zvol_minors;
111 
112 typedef struct zvol_extent {
113 	list_node_t	ze_node;
114 	dva_t		ze_dva;		/* dva associated with this extent */
115 	uint64_t	ze_nblks;	/* number of blocks in extent */
116 } zvol_extent_t;
117 
118 /*
119  * The in-core state of each volume.
120  */
121 typedef struct zvol_state {
122 	char		zv_name[MAXPATHLEN]; /* pool/dd name */
123 	uint64_t	zv_volsize;	/* amount of space we advertise */
124 	uint64_t	zv_volblocksize; /* volume block size */
125 	minor_t		zv_minor;	/* minor number */
126 	uint8_t		zv_min_bs;	/* minimum addressable block shift */
127 	uint8_t		zv_flags;	/* readonly, dumpified, etc. */
128 	objset_t	*zv_objset;	/* objset handle */
129 	uint32_t	zv_open_count[OTYPCNT];	/* open counts */
130 	uint32_t	zv_total_opens;	/* total open count */
131 	zilog_t		*zv_zilog;	/* ZIL handle */
132 	list_t		zv_extents;	/* List of extents for dump */
133 	rangelock_t	zv_rangelock;
134 	dnode_t		*zv_dn;		/* dnode hold */
135 } zvol_state_t;
136 
137 /*
138  * zvol specific flags
139  */
140 #define	ZVOL_RDONLY	0x1
141 #define	ZVOL_DUMPIFIED	0x2
142 #define	ZVOL_EXCL	0x4
143 #define	ZVOL_WCE	0x8
144 
145 /*
146  * zvol maximum transfer in one DMU tx.
147  */
148 int zvol_maxphys = DMU_MAX_ACCESS/2;
149 
150 /*
151  * Toggle unmap functionality.
152  */
153 boolean_t zvol_unmap_enabled = B_TRUE;
154 
155 /*
156  * If true, unmaps requested as synchronous are executed synchronously,
157  * otherwise all unmaps are asynchronous.
158  */
159 boolean_t zvol_unmap_sync_enabled = B_FALSE;
160 
161 extern int zfs_set_prop_nvlist(const char *, zprop_source_t,
162     nvlist_t *, nvlist_t *);
163 static int zvol_remove_zv(zvol_state_t *);
164 static int zvol_get_data(void *arg, lr_write_t *lr, char *buf,
165     struct lwb *lwb, zio_t *zio);
166 static int zvol_dumpify(zvol_state_t *zv);
167 static int zvol_dump_fini(zvol_state_t *zv);
168 static int zvol_dump_init(zvol_state_t *zv, boolean_t resize);
169 
170 static void
171 zvol_size_changed(zvol_state_t *zv, uint64_t volsize)
172 {
173 	dev_t dev = makedevice(ddi_driver_major(zfs_dip), zv->zv_minor);
174 
175 	zv->zv_volsize = volsize;
176 	VERIFY(ddi_prop_update_int64(dev, zfs_dip,
177 	    "Size", volsize) == DDI_SUCCESS);
178 	VERIFY(ddi_prop_update_int64(dev, zfs_dip,
179 	    "Nblocks", lbtodb(volsize)) == DDI_SUCCESS);
180 
181 	/* Notify specfs to invalidate the cached size */
182 	spec_size_invalidate(dev, VBLK);
183 	spec_size_invalidate(dev, VCHR);
184 }
185 
186 int
187 zvol_check_volsize(uint64_t volsize, uint64_t blocksize)
188 {
189 	if (volsize == 0)
190 		return (SET_ERROR(EINVAL));
191 
192 	if (volsize % blocksize != 0)
193 		return (SET_ERROR(EINVAL));
194 
195 #ifdef _ILP32
196 	if (volsize - 1 > SPEC_MAXOFFSET_T)
197 		return (SET_ERROR(EOVERFLOW));
198 #endif
199 	return (0);
200 }
201 
202 int
203 zvol_check_volblocksize(uint64_t volblocksize)
204 {
205 	if (volblocksize < SPA_MINBLOCKSIZE ||
206 	    volblocksize > SPA_OLD_MAXBLOCKSIZE ||
207 	    !ISP2(volblocksize))
208 		return (SET_ERROR(EDOM));
209 
210 	return (0);
211 }
212 
213 int
214 zvol_get_stats(objset_t *os, nvlist_t *nv)
215 {
216 	int error;
217 	dmu_object_info_t doi;
218 	uint64_t val;
219 
220 	error = zap_lookup(os, ZVOL_ZAP_OBJ, "size", 8, 1, &val);
221 	if (error)
222 		return (error);
223 
224 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_VOLSIZE, val);
225 
226 	error = dmu_object_info(os, ZVOL_OBJ, &doi);
227 
228 	if (error == 0) {
229 		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_VOLBLOCKSIZE,
230 		    doi.doi_data_block_size);
231 	}
232 
233 	return (error);
234 }
235 
236 static zvol_state_t *
237 zvol_minor_lookup(const char *name)
238 {
239 	minor_t minor;
240 	zvol_state_t *zv;
241 
242 	ASSERT(MUTEX_HELD(&zfsdev_state_lock));
243 
244 	for (minor = 1; minor <= ZFSDEV_MAX_MINOR; minor++) {
245 		zv = zfsdev_get_soft_state(minor, ZSST_ZVOL);
246 		if (zv == NULL)
247 			continue;
248 		if (strcmp(zv->zv_name, name) == 0)
249 			return (zv);
250 	}
251 
252 	return (NULL);
253 }
254 
255 /* extent mapping arg */
256 struct maparg {
257 	zvol_state_t	*ma_zv;
258 	uint64_t	ma_blks;
259 };
260 
261 /*ARGSUSED*/
262 static int
263 zvol_map_block(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
264     const zbookmark_phys_t *zb, const dnode_phys_t *dnp, void *arg)
265 {
266 	struct maparg *ma = arg;
267 	zvol_extent_t *ze;
268 	int bs = ma->ma_zv->zv_volblocksize;
269 
270 	if (bp == NULL || BP_IS_HOLE(bp) ||
271 	    zb->zb_object != ZVOL_OBJ || zb->zb_level != 0)
272 		return (0);
273 
274 	VERIFY(!BP_IS_EMBEDDED(bp));
275 
276 	VERIFY3U(ma->ma_blks, ==, zb->zb_blkid);
277 	ma->ma_blks++;
278 
279 	/* Abort immediately if we have encountered gang blocks */
280 	if (BP_IS_GANG(bp))
281 		return (SET_ERROR(EFRAGS));
282 
283 	/*
284 	 * See if the block is at the end of the previous extent.
285 	 */
286 	ze = list_tail(&ma->ma_zv->zv_extents);
287 	if (ze &&
288 	    DVA_GET_VDEV(BP_IDENTITY(bp)) == DVA_GET_VDEV(&ze->ze_dva) &&
289 	    DVA_GET_OFFSET(BP_IDENTITY(bp)) ==
290 	    DVA_GET_OFFSET(&ze->ze_dva) + ze->ze_nblks * bs) {
291 		ze->ze_nblks++;
292 		return (0);
293 	}
294 
295 	dprintf_bp(bp, "%s", "next blkptr:");
296 
297 	/* start a new extent */
298 	ze = kmem_zalloc(sizeof (zvol_extent_t), KM_SLEEP);
299 	ze->ze_dva = bp->blk_dva[0];	/* structure assignment */
300 	ze->ze_nblks = 1;
301 	list_insert_tail(&ma->ma_zv->zv_extents, ze);
302 	return (0);
303 }
304 
305 static void
306 zvol_free_extents(zvol_state_t *zv)
307 {
308 	zvol_extent_t *ze;
309 
310 	while (ze = list_head(&zv->zv_extents)) {
311 		list_remove(&zv->zv_extents, ze);
312 		kmem_free(ze, sizeof (zvol_extent_t));
313 	}
314 }
315 
316 static int
317 zvol_get_lbas(zvol_state_t *zv)
318 {
319 	objset_t *os = zv->zv_objset;
320 	struct maparg	ma;
321 	int		err;
322 
323 	ma.ma_zv = zv;
324 	ma.ma_blks = 0;
325 	zvol_free_extents(zv);
326 
327 	/* commit any in-flight changes before traversing the dataset */
328 	txg_wait_synced(dmu_objset_pool(os), 0);
329 	err = traverse_dataset(dmu_objset_ds(os), 0,
330 	    TRAVERSE_PRE | TRAVERSE_PREFETCH_METADATA, zvol_map_block, &ma);
331 	if (err || ma.ma_blks != (zv->zv_volsize / zv->zv_volblocksize)) {
332 		zvol_free_extents(zv);
333 		return (err ? err : EIO);
334 	}
335 
336 	return (0);
337 }
338 
339 /* ARGSUSED */
340 void
341 zvol_create_cb(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx)
342 {
343 	zfs_creat_t *zct = arg;
344 	nvlist_t *nvprops = zct->zct_props;
345 	int error;
346 	uint64_t volblocksize, volsize;
347 
348 	VERIFY(nvlist_lookup_uint64(nvprops,
349 	    zfs_prop_to_name(ZFS_PROP_VOLSIZE), &volsize) == 0);
350 	if (nvlist_lookup_uint64(nvprops,
351 	    zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE), &volblocksize) != 0)
352 		volblocksize = zfs_prop_default_numeric(ZFS_PROP_VOLBLOCKSIZE);
353 
354 	/*
355 	 * These properties must be removed from the list so the generic
356 	 * property setting step won't apply to them.
357 	 */
358 	VERIFY(nvlist_remove_all(nvprops,
359 	    zfs_prop_to_name(ZFS_PROP_VOLSIZE)) == 0);
360 	(void) nvlist_remove_all(nvprops,
361 	    zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE));
362 
363 	error = dmu_object_claim(os, ZVOL_OBJ, DMU_OT_ZVOL, volblocksize,
364 	    DMU_OT_NONE, 0, tx);
365 	ASSERT(error == 0);
366 
367 	error = zap_create_claim(os, ZVOL_ZAP_OBJ, DMU_OT_ZVOL_PROP,
368 	    DMU_OT_NONE, 0, tx);
369 	ASSERT(error == 0);
370 
371 	error = zap_update(os, ZVOL_ZAP_OBJ, "size", 8, 1, &volsize, tx);
372 	ASSERT(error == 0);
373 }
374 
375 /*
376  * Replay a TX_TRUNCATE ZIL transaction if asked.  TX_TRUNCATE is how we
377  * implement DKIOCFREE/free-long-range.
378  */
379 static int
380 zvol_replay_truncate(void *arg1, void *arg2, boolean_t byteswap)
381 {
382 	zvol_state_t *zv = arg1;
383 	lr_truncate_t *lr = arg2;
384 	uint64_t offset, length;
385 
386 	if (byteswap)
387 		byteswap_uint64_array(lr, sizeof (*lr));
388 
389 	offset = lr->lr_offset;
390 	length = lr->lr_length;
391 
392 	return (dmu_free_long_range(zv->zv_objset, ZVOL_OBJ, offset, length));
393 }
394 
395 /*
396  * Replay a TX_WRITE ZIL transaction that didn't get committed
397  * after a system failure
398  */
399 /* ARGSUSED */
400 static int
401 zvol_replay_write(void *arg1, void *arg2, boolean_t byteswap)
402 {
403 	zvol_state_t *zv = arg1;
404 	lr_write_t *lr = arg2;
405 	objset_t *os = zv->zv_objset;
406 	char *data = (char *)(lr + 1);	/* data follows lr_write_t */
407 	uint64_t offset, length;
408 	dmu_tx_t *tx;
409 	int error;
410 
411 	if (byteswap)
412 		byteswap_uint64_array(lr, sizeof (*lr));
413 
414 	offset = lr->lr_offset;
415 	length = lr->lr_length;
416 
417 	/* If it's a dmu_sync() block, write the whole block */
418 	if (lr->lr_common.lrc_reclen == sizeof (lr_write_t)) {
419 		uint64_t blocksize = BP_GET_LSIZE(&lr->lr_blkptr);
420 		if (length < blocksize) {
421 			offset -= offset % blocksize;
422 			length = blocksize;
423 		}
424 	}
425 
426 	tx = dmu_tx_create(os);
427 	dmu_tx_hold_write(tx, ZVOL_OBJ, offset, length);
428 	error = dmu_tx_assign(tx, TXG_WAIT);
429 	if (error) {
430 		dmu_tx_abort(tx);
431 	} else {
432 		dmu_write(os, ZVOL_OBJ, offset, length, data, tx);
433 		dmu_tx_commit(tx);
434 	}
435 
436 	return (error);
437 }
438 
439 /* ARGSUSED */
440 static int
441 zvol_replay_err(void *arg1, void *arg2, boolean_t byteswap)
442 {
443 	return (SET_ERROR(ENOTSUP));
444 }
445 
446 /*
447  * Callback vectors for replaying records.
448  * Only TX_WRITE and TX_TRUNCATE are needed for zvol.
449  */
450 zil_replay_func_t *zvol_replay_vector[TX_MAX_TYPE] = {
451 	zvol_replay_err,	/* 0 no such transaction type */
452 	zvol_replay_err,	/* TX_CREATE */
453 	zvol_replay_err,	/* TX_MKDIR */
454 	zvol_replay_err,	/* TX_MKXATTR */
455 	zvol_replay_err,	/* TX_SYMLINK */
456 	zvol_replay_err,	/* TX_REMOVE */
457 	zvol_replay_err,	/* TX_RMDIR */
458 	zvol_replay_err,	/* TX_LINK */
459 	zvol_replay_err,	/* TX_RENAME */
460 	zvol_replay_write,	/* TX_WRITE */
461 	zvol_replay_truncate,	/* TX_TRUNCATE */
462 	zvol_replay_err,	/* TX_SETATTR */
463 	zvol_replay_err,	/* TX_ACL */
464 	zvol_replay_err,	/* TX_CREATE_ACL */
465 	zvol_replay_err,	/* TX_CREATE_ATTR */
466 	zvol_replay_err,	/* TX_CREATE_ACL_ATTR */
467 	zvol_replay_err,	/* TX_MKDIR_ACL */
468 	zvol_replay_err,	/* TX_MKDIR_ATTR */
469 	zvol_replay_err,	/* TX_MKDIR_ACL_ATTR */
470 	zvol_replay_err,	/* TX_WRITE2 */
471 };
472 
473 int
474 zvol_name2minor(const char *name, minor_t *minor)
475 {
476 	zvol_state_t *zv;
477 
478 	mutex_enter(&zfsdev_state_lock);
479 	zv = zvol_minor_lookup(name);
480 	if (minor && zv)
481 		*minor = zv->zv_minor;
482 	mutex_exit(&zfsdev_state_lock);
483 	return (zv ? 0 : -1);
484 }
485 
486 /*
487  * Create a minor node (plus a whole lot more) for the specified volume.
488  */
489 int
490 zvol_create_minor(const char *name)
491 {
492 	zfs_soft_state_t *zs;
493 	zvol_state_t *zv;
494 	objset_t *os;
495 	dmu_object_info_t doi;
496 	minor_t minor = 0;
497 	char chrbuf[30], blkbuf[30];
498 	int error;
499 
500 	mutex_enter(&zfsdev_state_lock);
501 
502 	if (zvol_minor_lookup(name) != NULL) {
503 		mutex_exit(&zfsdev_state_lock);
504 		return (SET_ERROR(EEXIST));
505 	}
506 
507 	/* lie and say we're read-only */
508 	error = dmu_objset_own(name, DMU_OST_ZVOL, B_TRUE, B_TRUE, FTAG, &os);
509 
510 	if (error) {
511 		mutex_exit(&zfsdev_state_lock);
512 		return (error);
513 	}
514 
515 	if ((minor = zfsdev_minor_alloc()) == 0) {
516 		dmu_objset_disown(os, 1, FTAG);
517 		mutex_exit(&zfsdev_state_lock);
518 		return (SET_ERROR(ENXIO));
519 	}
520 
521 	if (ddi_soft_state_zalloc(zfsdev_state, minor) != DDI_SUCCESS) {
522 		dmu_objset_disown(os, 1, FTAG);
523 		mutex_exit(&zfsdev_state_lock);
524 		return (SET_ERROR(EAGAIN));
525 	}
526 	(void) ddi_prop_update_string(minor, zfs_dip, ZVOL_PROP_NAME,
527 	    (char *)name);
528 
529 	(void) snprintf(chrbuf, sizeof (chrbuf), "%u,raw", minor);
530 
531 	if (ddi_create_minor_node(zfs_dip, chrbuf, S_IFCHR,
532 	    minor, DDI_PSEUDO, 0) == DDI_FAILURE) {
533 		ddi_soft_state_free(zfsdev_state, minor);
534 		dmu_objset_disown(os, 1, FTAG);
535 		mutex_exit(&zfsdev_state_lock);
536 		return (SET_ERROR(EAGAIN));
537 	}
538 
539 	(void) snprintf(blkbuf, sizeof (blkbuf), "%u", minor);
540 
541 	if (ddi_create_minor_node(zfs_dip, blkbuf, S_IFBLK,
542 	    minor, DDI_PSEUDO, 0) == DDI_FAILURE) {
543 		ddi_remove_minor_node(zfs_dip, chrbuf);
544 		ddi_soft_state_free(zfsdev_state, minor);
545 		dmu_objset_disown(os, 1, FTAG);
546 		mutex_exit(&zfsdev_state_lock);
547 		return (SET_ERROR(EAGAIN));
548 	}
549 
550 	zs = ddi_get_soft_state(zfsdev_state, minor);
551 	zs->zss_type = ZSST_ZVOL;
552 	zv = zs->zss_data = kmem_zalloc(sizeof (zvol_state_t), KM_SLEEP);
553 	(void) strlcpy(zv->zv_name, name, MAXPATHLEN);
554 	zv->zv_min_bs = DEV_BSHIFT;
555 	zv->zv_minor = minor;
556 	zv->zv_objset = os;
557 	if (dmu_objset_is_snapshot(os) || !spa_writeable(dmu_objset_spa(os)))
558 		zv->zv_flags |= ZVOL_RDONLY;
559 	rangelock_init(&zv->zv_rangelock, NULL, NULL);
560 	list_create(&zv->zv_extents, sizeof (zvol_extent_t),
561 	    offsetof(zvol_extent_t, ze_node));
562 	/* get and cache the blocksize */
563 	error = dmu_object_info(os, ZVOL_OBJ, &doi);
564 	ASSERT(error == 0);
565 	zv->zv_volblocksize = doi.doi_data_block_size;
566 
567 	if (spa_writeable(dmu_objset_spa(os))) {
568 		if (zil_replay_disable)
569 			zil_destroy(dmu_objset_zil(os), B_FALSE);
570 		else
571 			zil_replay(os, zv, zvol_replay_vector);
572 	}
573 	dmu_objset_disown(os, 1, FTAG);
574 	zv->zv_objset = NULL;
575 
576 	zvol_minors++;
577 
578 	mutex_exit(&zfsdev_state_lock);
579 
580 	return (0);
581 }
582 
583 /*
584  * Remove minor node for the specified volume.
585  */
586 static int
587 zvol_remove_zv(zvol_state_t *zv)
588 {
589 	char nmbuf[20];
590 	minor_t minor = zv->zv_minor;
591 
592 	ASSERT(MUTEX_HELD(&zfsdev_state_lock));
593 	if (zv->zv_total_opens != 0)
594 		return (SET_ERROR(EBUSY));
595 
596 	(void) snprintf(nmbuf, sizeof (nmbuf), "%u,raw", minor);
597 	ddi_remove_minor_node(zfs_dip, nmbuf);
598 
599 	(void) snprintf(nmbuf, sizeof (nmbuf), "%u", minor);
600 	ddi_remove_minor_node(zfs_dip, nmbuf);
601 
602 	rangelock_fini(&zv->zv_rangelock);
603 
604 	kmem_free(zv, sizeof (zvol_state_t));
605 
606 	ddi_soft_state_free(zfsdev_state, minor);
607 
608 	zvol_minors--;
609 	return (0);
610 }
611 
612 int
613 zvol_remove_minor(const char *name)
614 {
615 	zvol_state_t *zv;
616 	int rc;
617 
618 	mutex_enter(&zfsdev_state_lock);
619 	if ((zv = zvol_minor_lookup(name)) == NULL) {
620 		mutex_exit(&zfsdev_state_lock);
621 		return (SET_ERROR(ENXIO));
622 	}
623 	rc = zvol_remove_zv(zv);
624 	mutex_exit(&zfsdev_state_lock);
625 	return (rc);
626 }
627 
628 int
629 zvol_first_open(zvol_state_t *zv, boolean_t rdonly)
630 {
631 	objset_t *os;
632 	uint64_t volsize;
633 	int error;
634 	uint64_t readonly;
635 	boolean_t ro;
636 
637 	ro = (rdonly || (strchr(zv->zv_name, '@') != NULL));
638 	error = dmu_objset_own(zv->zv_name, DMU_OST_ZVOL, ro, B_TRUE, zv, &os);
639 	if (error)
640 		return (error);
641 
642 	zv->zv_objset = os;
643 	error = zap_lookup(os, ZVOL_ZAP_OBJ, "size", 8, 1, &volsize);
644 	if (error) {
645 		ASSERT(error == 0);
646 		dmu_objset_disown(os, 1, zv);
647 		return (error);
648 	}
649 
650 	error = dnode_hold(os, ZVOL_OBJ, zvol_tag, &zv->zv_dn);
651 	if (error) {
652 		dmu_objset_disown(os, 1, zv);
653 		return (error);
654 	}
655 
656 	zvol_size_changed(zv, volsize);
657 	zv->zv_zilog = zil_open(os, zvol_get_data);
658 
659 	VERIFY(dsl_prop_get_integer(zv->zv_name, "readonly", &readonly,
660 	    NULL) == 0);
661 	if (readonly || dmu_objset_is_snapshot(os) ||
662 	    !spa_writeable(dmu_objset_spa(os)))
663 		zv->zv_flags |= ZVOL_RDONLY;
664 	else
665 		zv->zv_flags &= ~ZVOL_RDONLY;
666 	return (error);
667 }
668 
669 void
670 zvol_last_close(zvol_state_t *zv)
671 {
672 	zil_close(zv->zv_zilog);
673 	zv->zv_zilog = NULL;
674 
675 	dnode_rele(zv->zv_dn, zvol_tag);
676 	zv->zv_dn = NULL;
677 
678 	/*
679 	 * Evict cached data
680 	 */
681 	if (dsl_dataset_is_dirty(dmu_objset_ds(zv->zv_objset)) &&
682 	    !(zv->zv_flags & ZVOL_RDONLY))
683 		txg_wait_synced(dmu_objset_pool(zv->zv_objset), 0);
684 	dmu_objset_evict_dbufs(zv->zv_objset);
685 
686 	dmu_objset_disown(zv->zv_objset, 1, zv);
687 	zv->zv_objset = NULL;
688 }
689 
690 int
691 zvol_prealloc(zvol_state_t *zv)
692 {
693 	objset_t *os = zv->zv_objset;
694 	dmu_tx_t *tx;
695 	uint64_t refd, avail, usedobjs, availobjs;
696 	uint64_t resid = zv->zv_volsize;
697 	uint64_t off = 0;
698 
699 	/* Check the space usage before attempting to allocate the space */
700 	dmu_objset_space(os, &refd, &avail, &usedobjs, &availobjs);
701 	if (avail < zv->zv_volsize)
702 		return (SET_ERROR(ENOSPC));
703 
704 	/* Free old extents if they exist */
705 	zvol_free_extents(zv);
706 
707 	while (resid != 0) {
708 		int error;
709 		uint64_t bytes = MIN(resid, SPA_OLD_MAXBLOCKSIZE);
710 
711 		tx = dmu_tx_create(os);
712 		dmu_tx_hold_write(tx, ZVOL_OBJ, off, bytes);
713 		error = dmu_tx_assign(tx, TXG_WAIT);
714 		if (error) {
715 			dmu_tx_abort(tx);
716 			(void) dmu_free_long_range(os, ZVOL_OBJ, 0, off);
717 			return (error);
718 		}
719 		dmu_prealloc(os, ZVOL_OBJ, off, bytes, tx);
720 		dmu_tx_commit(tx);
721 		off += bytes;
722 		resid -= bytes;
723 	}
724 	txg_wait_synced(dmu_objset_pool(os), 0);
725 
726 	return (0);
727 }
728 
729 static int
730 zvol_update_volsize(objset_t *os, uint64_t volsize)
731 {
732 	dmu_tx_t *tx;
733 	int error;
734 	uint64_t txg;
735 
736 	ASSERT(MUTEX_HELD(&zfsdev_state_lock));
737 
738 	tx = dmu_tx_create(os);
739 	dmu_tx_hold_zap(tx, ZVOL_ZAP_OBJ, TRUE, NULL);
740 	dmu_tx_mark_netfree(tx);
741 	error = dmu_tx_assign(tx, TXG_WAIT);
742 	if (error) {
743 		dmu_tx_abort(tx);
744 		return (error);
745 	}
746 	txg = dmu_tx_get_txg(tx);
747 
748 	error = zap_update(os, ZVOL_ZAP_OBJ, "size", 8, 1,
749 	    &volsize, tx);
750 	dmu_tx_commit(tx);
751 
752 	txg_wait_synced(dmu_objset_pool(os), txg);
753 
754 	if (error == 0)
755 		error = dmu_free_long_range(os,
756 		    ZVOL_OBJ, volsize, DMU_OBJECT_END);
757 	return (error);
758 }
759 
760 void
761 zvol_remove_minors(const char *name)
762 {
763 	zvol_state_t *zv;
764 	char *namebuf;
765 	minor_t minor;
766 
767 	namebuf = kmem_zalloc(strlen(name) + 2, KM_SLEEP);
768 	(void) strncpy(namebuf, name, strlen(name));
769 	(void) strcat(namebuf, "/");
770 	mutex_enter(&zfsdev_state_lock);
771 	for (minor = 1; minor <= ZFSDEV_MAX_MINOR; minor++) {
772 
773 		zv = zfsdev_get_soft_state(minor, ZSST_ZVOL);
774 		if (zv == NULL)
775 			continue;
776 		if (strncmp(namebuf, zv->zv_name, strlen(namebuf)) == 0)
777 			(void) zvol_remove_zv(zv);
778 	}
779 	kmem_free(namebuf, strlen(name) + 2);
780 
781 	mutex_exit(&zfsdev_state_lock);
782 }
783 
784 static int
785 zvol_update_live_volsize(zvol_state_t *zv, uint64_t volsize)
786 {
787 	uint64_t old_volsize = 0ULL;
788 	int error = 0;
789 
790 	ASSERT(MUTEX_HELD(&zfsdev_state_lock));
791 
792 	/*
793 	 * Reinitialize the dump area to the new size. If we
794 	 * failed to resize the dump area then restore it back to
795 	 * its original size.  We must set the new volsize prior
796 	 * to calling dumpvp_resize() to ensure that the devices'
797 	 * size(9P) is not visible by the dump subsystem.
798 	 */
799 	old_volsize = zv->zv_volsize;
800 	zvol_size_changed(zv, volsize);
801 
802 	if (zv->zv_flags & ZVOL_DUMPIFIED) {
803 		if ((error = zvol_dumpify(zv)) != 0 ||
804 		    (error = dumpvp_resize()) != 0) {
805 			int dumpify_error;
806 
807 			(void) zvol_update_volsize(zv->zv_objset, old_volsize);
808 			zvol_size_changed(zv, old_volsize);
809 			dumpify_error = zvol_dumpify(zv);
810 			error = dumpify_error ? dumpify_error : error;
811 		}
812 	}
813 
814 	/*
815 	 * Generate a LUN expansion event.
816 	 */
817 	if (error == 0) {
818 		sysevent_id_t eid;
819 		nvlist_t *attr;
820 		char *physpath = kmem_zalloc(MAXPATHLEN, KM_SLEEP);
821 
822 		(void) snprintf(physpath, MAXPATHLEN, "%s%u", ZVOL_PSEUDO_DEV,
823 		    zv->zv_minor);
824 
825 		VERIFY(nvlist_alloc(&attr, NV_UNIQUE_NAME, KM_SLEEP) == 0);
826 		VERIFY(nvlist_add_string(attr, DEV_PHYS_PATH, physpath) == 0);
827 
828 		(void) ddi_log_sysevent(zfs_dip, SUNW_VENDOR, EC_DEV_STATUS,
829 		    ESC_DEV_DLE, attr, &eid, DDI_SLEEP);
830 
831 		nvlist_free(attr);
832 		kmem_free(physpath, MAXPATHLEN);
833 	}
834 	return (error);
835 }
836 
837 int
838 zvol_set_volsize(const char *name, uint64_t volsize)
839 {
840 	zvol_state_t *zv = NULL;
841 	objset_t *os;
842 	int error;
843 	dmu_object_info_t doi;
844 	uint64_t readonly;
845 	boolean_t owned = B_FALSE;
846 
847 	error = dsl_prop_get_integer(name,
848 	    zfs_prop_to_name(ZFS_PROP_READONLY), &readonly, NULL);
849 	if (error != 0)
850 		return (error);
851 	if (readonly)
852 		return (SET_ERROR(EROFS));
853 
854 	mutex_enter(&zfsdev_state_lock);
855 	zv = zvol_minor_lookup(name);
856 
857 	if (zv == NULL || zv->zv_objset == NULL) {
858 		if ((error = dmu_objset_own(name, DMU_OST_ZVOL, B_FALSE, B_TRUE,
859 		    FTAG, &os)) != 0) {
860 			mutex_exit(&zfsdev_state_lock);
861 			return (error);
862 		}
863 		owned = B_TRUE;
864 		if (zv != NULL)
865 			zv->zv_objset = os;
866 	} else {
867 		os = zv->zv_objset;
868 	}
869 
870 	if ((error = dmu_object_info(os, ZVOL_OBJ, &doi)) != 0 ||
871 	    (error = zvol_check_volsize(volsize, doi.doi_data_block_size)) != 0)
872 		goto out;
873 
874 	error = zvol_update_volsize(os, volsize);
875 
876 	if (error == 0 && zv != NULL)
877 		error = zvol_update_live_volsize(zv, volsize);
878 out:
879 	if (owned) {
880 		dmu_objset_disown(os, B_TRUE, FTAG);
881 		if (zv != NULL)
882 			zv->zv_objset = NULL;
883 	}
884 	mutex_exit(&zfsdev_state_lock);
885 	return (error);
886 }
887 
888 /*ARGSUSED*/
889 int
890 zvol_open(dev_t *devp, int flag, int otyp, cred_t *cr)
891 {
892 	zvol_state_t *zv;
893 	int err = 0;
894 
895 	mutex_enter(&zfsdev_state_lock);
896 
897 	zv = zfsdev_get_soft_state(getminor(*devp), ZSST_ZVOL);
898 	if (zv == NULL) {
899 		mutex_exit(&zfsdev_state_lock);
900 		return (SET_ERROR(ENXIO));
901 	}
902 
903 	if (zv->zv_total_opens == 0)
904 		err = zvol_first_open(zv, !(flag & FWRITE));
905 	if (err) {
906 		mutex_exit(&zfsdev_state_lock);
907 		return (err);
908 	}
909 
910 	if ((flag & FWRITE) && (zv->zv_flags & ZVOL_RDONLY)) {
911 		err = SET_ERROR(EROFS);
912 		goto out;
913 	}
914 	if (zv->zv_flags & ZVOL_EXCL) {
915 		err = SET_ERROR(EBUSY);
916 		goto out;
917 	}
918 	if (flag & FEXCL) {
919 		if (zv->zv_total_opens != 0) {
920 			err = SET_ERROR(EBUSY);
921 			goto out;
922 		}
923 		zv->zv_flags |= ZVOL_EXCL;
924 	}
925 
926 	if (zv->zv_open_count[otyp] == 0 || otyp == OTYP_LYR) {
927 		zv->zv_open_count[otyp]++;
928 		zv->zv_total_opens++;
929 	}
930 	mutex_exit(&zfsdev_state_lock);
931 
932 	return (err);
933 out:
934 	if (zv->zv_total_opens == 0)
935 		zvol_last_close(zv);
936 	mutex_exit(&zfsdev_state_lock);
937 	return (err);
938 }
939 
940 /*ARGSUSED*/
941 int
942 zvol_close(dev_t dev, int flag, int otyp, cred_t *cr)
943 {
944 	minor_t minor = getminor(dev);
945 	zvol_state_t *zv;
946 	int error = 0;
947 
948 	mutex_enter(&zfsdev_state_lock);
949 
950 	zv = zfsdev_get_soft_state(minor, ZSST_ZVOL);
951 	if (zv == NULL) {
952 		mutex_exit(&zfsdev_state_lock);
953 		return (SET_ERROR(ENXIO));
954 	}
955 
956 	if (zv->zv_flags & ZVOL_EXCL) {
957 		ASSERT(zv->zv_total_opens == 1);
958 		zv->zv_flags &= ~ZVOL_EXCL;
959 	}
960 
961 	/*
962 	 * If the open count is zero, this is a spurious close.
963 	 * That indicates a bug in the kernel / DDI framework.
964 	 */
965 	ASSERT(zv->zv_open_count[otyp] != 0);
966 	ASSERT(zv->zv_total_opens != 0);
967 
968 	/*
969 	 * You may get multiple opens, but only one close.
970 	 */
971 	zv->zv_open_count[otyp]--;
972 	zv->zv_total_opens--;
973 
974 	if (zv->zv_total_opens == 0)
975 		zvol_last_close(zv);
976 
977 	mutex_exit(&zfsdev_state_lock);
978 	return (error);
979 }
980 
981 /* ARGSUSED */
982 static void
983 zvol_get_done(zgd_t *zgd, int error)
984 {
985 	if (zgd->zgd_db)
986 		dmu_buf_rele(zgd->zgd_db, zgd);
987 
988 	rangelock_exit(zgd->zgd_lr);
989 
990 	kmem_free(zgd, sizeof (zgd_t));
991 }
992 
993 /*
994  * Get data to generate a TX_WRITE intent log record.
995  */
996 static int
997 zvol_get_data(void *arg, lr_write_t *lr, char *buf, struct lwb *lwb, zio_t *zio)
998 {
999 	zvol_state_t *zv = arg;
1000 	uint64_t offset = lr->lr_offset;
1001 	uint64_t size = lr->lr_length;	/* length of user data */
1002 	dmu_buf_t *db;
1003 	zgd_t *zgd;
1004 	int error;
1005 
1006 	ASSERT3P(lwb, !=, NULL);
1007 	ASSERT3P(zio, !=, NULL);
1008 	ASSERT3U(size, !=, 0);
1009 
1010 	zgd = kmem_zalloc(sizeof (zgd_t), KM_SLEEP);
1011 	zgd->zgd_lwb = lwb;
1012 
1013 	/*
1014 	 * Write records come in two flavors: immediate and indirect.
1015 	 * For small writes it's cheaper to store the data with the
1016 	 * log record (immediate); for large writes it's cheaper to
1017 	 * sync the data and get a pointer to it (indirect) so that
1018 	 * we don't have to write the data twice.
1019 	 */
1020 	if (buf != NULL) { /* immediate write */
1021 		zgd->zgd_lr = rangelock_enter(&zv->zv_rangelock, offset, size,
1022 		    RL_READER);
1023 		error = dmu_read_by_dnode(zv->zv_dn, offset, size, buf,
1024 		    DMU_READ_NO_PREFETCH);
1025 	} else { /* indirect write */
1026 		/*
1027 		 * Have to lock the whole block to ensure when it's written out
1028 		 * and its checksum is being calculated that no one can change
1029 		 * the data. Contrarily to zfs_get_data we need not re-check
1030 		 * blocksize after we get the lock because it cannot be changed.
1031 		 */
1032 		size = zv->zv_volblocksize;
1033 		offset = P2ALIGN(offset, size);
1034 		zgd->zgd_lr = rangelock_enter(&zv->zv_rangelock, offset, size,
1035 		    RL_READER);
1036 		error = dmu_buf_hold_by_dnode(zv->zv_dn, offset, zgd, &db,
1037 		    DMU_READ_NO_PREFETCH);
1038 		if (error == 0) {
1039 			blkptr_t *bp = &lr->lr_blkptr;
1040 
1041 			zgd->zgd_db = db;
1042 			zgd->zgd_bp = bp;
1043 
1044 			ASSERT(db->db_offset == offset);
1045 			ASSERT(db->db_size == size);
1046 
1047 			error = dmu_sync(zio, lr->lr_common.lrc_txg,
1048 			    zvol_get_done, zgd);
1049 
1050 			if (error == 0)
1051 				return (0);
1052 		}
1053 	}
1054 
1055 	zvol_get_done(zgd, error);
1056 
1057 	return (error);
1058 }
1059 
1060 /*
1061  * zvol_log_write() handles synchronous writes using TX_WRITE ZIL transactions.
1062  *
1063  * We store data in the log buffers if it's small enough.
1064  * Otherwise we will later flush the data out via dmu_sync().
1065  */
1066 ssize_t zvol_immediate_write_sz = 32768;
1067 
1068 static void
1069 zvol_log_write(zvol_state_t *zv, dmu_tx_t *tx, offset_t off, ssize_t resid,
1070     boolean_t sync)
1071 {
1072 	uint32_t blocksize = zv->zv_volblocksize;
1073 	zilog_t *zilog = zv->zv_zilog;
1074 	itx_wr_state_t write_state;
1075 
1076 	if (zil_replaying(zilog, tx))
1077 		return;
1078 
1079 	if (zilog->zl_logbias == ZFS_LOGBIAS_THROUGHPUT)
1080 		write_state = WR_INDIRECT;
1081 	else if (!spa_has_slogs(zilog->zl_spa) &&
1082 	    resid >= blocksize && blocksize > zvol_immediate_write_sz)
1083 		write_state = WR_INDIRECT;
1084 	else if (sync)
1085 		write_state = WR_COPIED;
1086 	else
1087 		write_state = WR_NEED_COPY;
1088 
1089 	while (resid) {
1090 		itx_t *itx;
1091 		lr_write_t *lr;
1092 		itx_wr_state_t wr_state = write_state;
1093 		ssize_t len = resid;
1094 
1095 		if (wr_state == WR_COPIED && resid > ZIL_MAX_COPIED_DATA)
1096 			wr_state = WR_NEED_COPY;
1097 		else if (wr_state == WR_INDIRECT)
1098 			len = MIN(blocksize - P2PHASE(off, blocksize), resid);
1099 
1100 		itx = zil_itx_create(TX_WRITE, sizeof (*lr) +
1101 		    (wr_state == WR_COPIED ? len : 0));
1102 		lr = (lr_write_t *)&itx->itx_lr;
1103 		if (wr_state == WR_COPIED && dmu_read_by_dnode(zv->zv_dn,
1104 		    off, len, lr + 1, DMU_READ_NO_PREFETCH) != 0) {
1105 			zil_itx_destroy(itx);
1106 			itx = zil_itx_create(TX_WRITE, sizeof (*lr));
1107 			lr = (lr_write_t *)&itx->itx_lr;
1108 			wr_state = WR_NEED_COPY;
1109 		}
1110 
1111 		itx->itx_wr_state = wr_state;
1112 		lr->lr_foid = ZVOL_OBJ;
1113 		lr->lr_offset = off;
1114 		lr->lr_length = len;
1115 		lr->lr_blkoff = 0;
1116 		BP_ZERO(&lr->lr_blkptr);
1117 
1118 		itx->itx_private = zv;
1119 		itx->itx_sync = sync;
1120 
1121 		zil_itx_assign(zilog, itx, tx);
1122 
1123 		off += len;
1124 		resid -= len;
1125 	}
1126 }
1127 
1128 static int
1129 zvol_dumpio_vdev(vdev_t *vd, void *addr, uint64_t offset, uint64_t origoffset,
1130     uint64_t size, boolean_t doread, boolean_t isdump)
1131 {
1132 	vdev_disk_t *dvd;
1133 	int c;
1134 	int numerrors = 0;
1135 
1136 	if (vd->vdev_ops == &vdev_mirror_ops ||
1137 	    vd->vdev_ops == &vdev_replacing_ops ||
1138 	    vd->vdev_ops == &vdev_spare_ops) {
1139 		for (c = 0; c < vd->vdev_children; c++) {
1140 			int err = zvol_dumpio_vdev(vd->vdev_child[c],
1141 			    addr, offset, origoffset, size, doread, isdump);
1142 			if (err != 0) {
1143 				numerrors++;
1144 			} else if (doread) {
1145 				break;
1146 			}
1147 		}
1148 	}
1149 
1150 	if (!vd->vdev_ops->vdev_op_leaf && vd->vdev_ops != &vdev_raidz_ops)
1151 		return (numerrors < vd->vdev_children ? 0 : EIO);
1152 
1153 	if (doread && !vdev_readable(vd))
1154 		return (SET_ERROR(EIO));
1155 	else if (!doread && !vdev_writeable(vd))
1156 		return (SET_ERROR(EIO));
1157 
1158 	if (vd->vdev_ops == &vdev_raidz_ops) {
1159 		return (vdev_raidz_physio(vd,
1160 		    addr, size, offset, origoffset, doread, isdump));
1161 	}
1162 
1163 	offset += VDEV_LABEL_START_SIZE;
1164 
1165 	if (ddi_in_panic() || isdump) {
1166 		ASSERT(!doread);
1167 		if (doread)
1168 			return (SET_ERROR(EIO));
1169 		dvd = vd->vdev_tsd;
1170 		ASSERT3P(dvd, !=, NULL);
1171 		return (ldi_dump(dvd->vd_lh, addr, lbtodb(offset),
1172 		    lbtodb(size)));
1173 	} else {
1174 		dvd = vd->vdev_tsd;
1175 		ASSERT3P(dvd, !=, NULL);
1176 		return (vdev_disk_ldi_physio(dvd->vd_lh, addr, size,
1177 		    offset, doread ? B_READ : B_WRITE));
1178 	}
1179 }
1180 
1181 static int
1182 zvol_dumpio(zvol_state_t *zv, void *addr, uint64_t offset, uint64_t size,
1183     boolean_t doread, boolean_t isdump)
1184 {
1185 	vdev_t *vd;
1186 	int error;
1187 	zvol_extent_t *ze;
1188 	spa_t *spa = dmu_objset_spa(zv->zv_objset);
1189 
1190 	/* Must be sector aligned, and not stradle a block boundary. */
1191 	if (P2PHASE(offset, DEV_BSIZE) || P2PHASE(size, DEV_BSIZE) ||
1192 	    P2BOUNDARY(offset, size, zv->zv_volblocksize)) {
1193 		return (SET_ERROR(EINVAL));
1194 	}
1195 	ASSERT(size <= zv->zv_volblocksize);
1196 
1197 	/* Locate the extent this belongs to */
1198 	ze = list_head(&zv->zv_extents);
1199 	while (offset >= ze->ze_nblks * zv->zv_volblocksize) {
1200 		offset -= ze->ze_nblks * zv->zv_volblocksize;
1201 		ze = list_next(&zv->zv_extents, ze);
1202 	}
1203 
1204 	if (ze == NULL)
1205 		return (SET_ERROR(EINVAL));
1206 
1207 	if (!ddi_in_panic())
1208 		spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);
1209 
1210 	vd = vdev_lookup_top(spa, DVA_GET_VDEV(&ze->ze_dva));
1211 	offset += DVA_GET_OFFSET(&ze->ze_dva);
1212 	error = zvol_dumpio_vdev(vd, addr, offset, DVA_GET_OFFSET(&ze->ze_dva),
1213 	    size, doread, isdump);
1214 
1215 	if (!ddi_in_panic())
1216 		spa_config_exit(spa, SCL_STATE, FTAG);
1217 
1218 	return (error);
1219 }
1220 
1221 int
1222 zvol_strategy(buf_t *bp)
1223 {
1224 	zfs_soft_state_t *zs = NULL;
1225 	zvol_state_t *zv;
1226 	uint64_t off, volsize;
1227 	size_t resid;
1228 	char *addr;
1229 	objset_t *os;
1230 	int error = 0;
1231 	boolean_t doread = bp->b_flags & B_READ;
1232 	boolean_t is_dumpified;
1233 	boolean_t sync;
1234 
1235 	if (getminor(bp->b_edev) == 0) {
1236 		error = SET_ERROR(EINVAL);
1237 	} else {
1238 		zs = ddi_get_soft_state(zfsdev_state, getminor(bp->b_edev));
1239 		if (zs == NULL)
1240 			error = SET_ERROR(ENXIO);
1241 		else if (zs->zss_type != ZSST_ZVOL)
1242 			error = SET_ERROR(EINVAL);
1243 	}
1244 
1245 	if (error) {
1246 		bioerror(bp, error);
1247 		biodone(bp);
1248 		return (0);
1249 	}
1250 
1251 	zv = zs->zss_data;
1252 
1253 	if (!(bp->b_flags & B_READ) && (zv->zv_flags & ZVOL_RDONLY)) {
1254 		bioerror(bp, EROFS);
1255 		biodone(bp);
1256 		return (0);
1257 	}
1258 
1259 	off = ldbtob(bp->b_blkno);
1260 	volsize = zv->zv_volsize;
1261 
1262 	os = zv->zv_objset;
1263 	ASSERT(os != NULL);
1264 
1265 	bp_mapin(bp);
1266 	addr = bp->b_un.b_addr;
1267 	resid = bp->b_bcount;
1268 
1269 	if (resid > 0 && (off < 0 || off >= volsize)) {
1270 		bioerror(bp, EIO);
1271 		biodone(bp);
1272 		return (0);
1273 	}
1274 
1275 	is_dumpified = zv->zv_flags & ZVOL_DUMPIFIED;
1276 	sync = ((!(bp->b_flags & B_ASYNC) &&
1277 	    !(zv->zv_flags & ZVOL_WCE)) ||
1278 	    (zv->zv_objset->os_sync == ZFS_SYNC_ALWAYS)) &&
1279 	    !doread && !is_dumpified;
1280 
1281 	smt_begin_unsafe();
1282 
1283 	/*
1284 	 * There must be no buffer changes when doing a dmu_sync() because
1285 	 * we can't change the data whilst calculating the checksum.
1286 	 */
1287 	locked_range_t *lr = rangelock_enter(&zv->zv_rangelock, off, resid,
1288 	    doread ? RL_READER : RL_WRITER);
1289 
1290 	while (resid != 0 && off < volsize) {
1291 		size_t size = MIN(resid, zvol_maxphys);
1292 		if (is_dumpified) {
1293 			size = MIN(size, P2END(off, zv->zv_volblocksize) - off);
1294 			error = zvol_dumpio(zv, addr, off, size,
1295 			    doread, B_FALSE);
1296 		} else if (doread) {
1297 			error = dmu_read(os, ZVOL_OBJ, off, size, addr,
1298 			    DMU_READ_PREFETCH);
1299 		} else {
1300 			dmu_tx_t *tx = dmu_tx_create(os);
1301 			dmu_tx_hold_write(tx, ZVOL_OBJ, off, size);
1302 			error = dmu_tx_assign(tx, TXG_WAIT);
1303 			if (error) {
1304 				dmu_tx_abort(tx);
1305 			} else {
1306 				dmu_write(os, ZVOL_OBJ, off, size, addr, tx);
1307 				zvol_log_write(zv, tx, off, size, sync);
1308 				dmu_tx_commit(tx);
1309 			}
1310 		}
1311 		if (error) {
1312 			/* convert checksum errors into IO errors */
1313 			if (error == ECKSUM)
1314 				error = SET_ERROR(EIO);
1315 			break;
1316 		}
1317 		off += size;
1318 		addr += size;
1319 		resid -= size;
1320 	}
1321 	rangelock_exit(lr);
1322 
1323 	if ((bp->b_resid = resid) == bp->b_bcount)
1324 		bioerror(bp, off > volsize ? EINVAL : error);
1325 
1326 	if (sync)
1327 		zil_commit(zv->zv_zilog, ZVOL_OBJ);
1328 	biodone(bp);
1329 
1330 	smt_end_unsafe();
1331 
1332 	return (0);
1333 }
1334 
1335 /*
1336  * Set the buffer count to the zvol maximum transfer.
1337  * Using our own routine instead of the default minphys()
1338  * means that for larger writes we write bigger buffers on X86
1339  * (128K instead of 56K) and flush the disk write cache less often
1340  * (every zvol_maxphys - currently 1MB) instead of minphys (currently
1341  * 56K on X86 and 128K on sparc).
1342  */
1343 void
1344 zvol_minphys(struct buf *bp)
1345 {
1346 	if (bp->b_bcount > zvol_maxphys)
1347 		bp->b_bcount = zvol_maxphys;
1348 }
1349 
1350 int
1351 zvol_dump(dev_t dev, caddr_t addr, daddr_t blkno, int nblocks)
1352 {
1353 	minor_t minor = getminor(dev);
1354 	zvol_state_t *zv;
1355 	int error = 0;
1356 	uint64_t size;
1357 	uint64_t boff;
1358 	uint64_t resid;
1359 
1360 	zv = zfsdev_get_soft_state(minor, ZSST_ZVOL);
1361 	if (zv == NULL)
1362 		return (SET_ERROR(ENXIO));
1363 
1364 	if ((zv->zv_flags & ZVOL_DUMPIFIED) == 0)
1365 		return (SET_ERROR(EINVAL));
1366 
1367 	boff = ldbtob(blkno);
1368 	resid = ldbtob(nblocks);
1369 
1370 	VERIFY3U(boff + resid, <=, zv->zv_volsize);
1371 
1372 	while (resid) {
1373 		size = MIN(resid, P2END(boff, zv->zv_volblocksize) - boff);
1374 		error = zvol_dumpio(zv, addr, boff, size, B_FALSE, B_TRUE);
1375 		if (error)
1376 			break;
1377 		boff += size;
1378 		addr += size;
1379 		resid -= size;
1380 	}
1381 
1382 	return (error);
1383 }
1384 
1385 /*ARGSUSED*/
1386 int
1387 zvol_read(dev_t dev, uio_t *uio, cred_t *cr)
1388 {
1389 	minor_t minor = getminor(dev);
1390 	zvol_state_t *zv;
1391 	uint64_t volsize;
1392 	int error = 0;
1393 
1394 	zv = zfsdev_get_soft_state(minor, ZSST_ZVOL);
1395 	if (zv == NULL)
1396 		return (SET_ERROR(ENXIO));
1397 
1398 	volsize = zv->zv_volsize;
1399 	if (uio->uio_resid > 0 &&
1400 	    (uio->uio_loffset < 0 || uio->uio_loffset >= volsize))
1401 		return (SET_ERROR(EIO));
1402 
1403 	if (zv->zv_flags & ZVOL_DUMPIFIED) {
1404 		error = physio(zvol_strategy, NULL, dev, B_READ,
1405 		    zvol_minphys, uio);
1406 		return (error);
1407 	}
1408 
1409 	smt_begin_unsafe();
1410 
1411 	locked_range_t *lr = rangelock_enter(&zv->zv_rangelock,
1412 	    uio->uio_loffset, uio->uio_resid, RL_READER);
1413 	while (uio->uio_resid > 0 && uio->uio_loffset < volsize) {
1414 		uint64_t bytes = MIN(uio->uio_resid, DMU_MAX_ACCESS >> 1);
1415 
1416 		/* don't read past the end */
1417 		if (bytes > volsize - uio->uio_loffset)
1418 			bytes = volsize - uio->uio_loffset;
1419 
1420 		error =  dmu_read_uio(zv->zv_objset, ZVOL_OBJ, uio, bytes);
1421 		if (error) {
1422 			/* convert checksum errors into IO errors */
1423 			if (error == ECKSUM)
1424 				error = SET_ERROR(EIO);
1425 			break;
1426 		}
1427 	}
1428 	rangelock_exit(lr);
1429 
1430 	smt_end_unsafe();
1431 
1432 	return (error);
1433 }
1434 
1435 /*ARGSUSED*/
1436 int
1437 zvol_write(dev_t dev, uio_t *uio, cred_t *cr)
1438 {
1439 	minor_t minor = getminor(dev);
1440 	zvol_state_t *zv;
1441 	uint64_t volsize;
1442 	int error = 0;
1443 	boolean_t sync;
1444 
1445 	zv = zfsdev_get_soft_state(minor, ZSST_ZVOL);
1446 	if (zv == NULL)
1447 		return (SET_ERROR(ENXIO));
1448 
1449 	volsize = zv->zv_volsize;
1450 	if (uio->uio_resid > 0 &&
1451 	    (uio->uio_loffset < 0 || uio->uio_loffset >= volsize))
1452 		return (SET_ERROR(EIO));
1453 
1454 	if (zv->zv_flags & ZVOL_DUMPIFIED) {
1455 		error = physio(zvol_strategy, NULL, dev, B_WRITE,
1456 		    zvol_minphys, uio);
1457 		return (error);
1458 	}
1459 
1460 	smt_begin_unsafe();
1461 
1462 	sync = !(zv->zv_flags & ZVOL_WCE) ||
1463 	    (zv->zv_objset->os_sync == ZFS_SYNC_ALWAYS);
1464 
1465 	locked_range_t *lr = rangelock_enter(&zv->zv_rangelock,
1466 	    uio->uio_loffset, uio->uio_resid, RL_WRITER);
1467 	while (uio->uio_resid > 0 && uio->uio_loffset < volsize) {
1468 		uint64_t bytes = MIN(uio->uio_resid, DMU_MAX_ACCESS >> 1);
1469 		uint64_t off = uio->uio_loffset;
1470 		dmu_tx_t *tx = dmu_tx_create(zv->zv_objset);
1471 
1472 		if (bytes > volsize - off)	/* don't write past the end */
1473 			bytes = volsize - off;
1474 
1475 		dmu_tx_hold_write(tx, ZVOL_OBJ, off, bytes);
1476 		error = dmu_tx_assign(tx, TXG_WAIT);
1477 		if (error) {
1478 			dmu_tx_abort(tx);
1479 			break;
1480 		}
1481 		error = dmu_write_uio_dnode(zv->zv_dn, uio, bytes, tx);
1482 		if (error == 0)
1483 			zvol_log_write(zv, tx, off, bytes, sync);
1484 		dmu_tx_commit(tx);
1485 
1486 		if (error)
1487 			break;
1488 	}
1489 	rangelock_exit(lr);
1490 
1491 	if (sync)
1492 		zil_commit(zv->zv_zilog, ZVOL_OBJ);
1493 
1494 	smt_end_unsafe();
1495 
1496 	return (error);
1497 }
1498 
1499 int
1500 zvol_getefi(void *arg, int flag, uint64_t vs, uint8_t bs)
1501 {
1502 	struct uuid uuid = EFI_RESERVED;
1503 	efi_gpe_t gpe = { 0 };
1504 	uint32_t crc;
1505 	dk_efi_t efi;
1506 	int length;
1507 	char *ptr;
1508 
1509 	if (ddi_copyin(arg, &efi, sizeof (dk_efi_t), flag))
1510 		return (SET_ERROR(EFAULT));
1511 	ptr = (char *)(uintptr_t)efi.dki_data_64;
1512 	length = efi.dki_length;
1513 	/*
1514 	 * Some clients may attempt to request a PMBR for the
1515 	 * zvol.  Currently this interface will return EINVAL to
1516 	 * such requests.  These requests could be supported by
1517 	 * adding a check for lba == 0 and consing up an appropriate
1518 	 * PMBR.
1519 	 */
1520 	if (efi.dki_lba < 1 || efi.dki_lba > 2 || length <= 0)
1521 		return (SET_ERROR(EINVAL));
1522 
1523 	gpe.efi_gpe_StartingLBA = LE_64(34ULL);
1524 	gpe.efi_gpe_EndingLBA = LE_64((vs >> bs) - 1);
1525 	UUID_LE_CONVERT(gpe.efi_gpe_PartitionTypeGUID, uuid);
1526 
1527 	if (efi.dki_lba == 1) {
1528 		efi_gpt_t gpt = { 0 };
1529 
1530 		gpt.efi_gpt_Signature = LE_64(EFI_SIGNATURE);
1531 		gpt.efi_gpt_Revision = LE_32(EFI_VERSION_CURRENT);
1532 		gpt.efi_gpt_HeaderSize = LE_32(EFI_HEADER_SIZE);
1533 		gpt.efi_gpt_MyLBA = LE_64(1ULL);
1534 		gpt.efi_gpt_FirstUsableLBA = LE_64(34ULL);
1535 		gpt.efi_gpt_LastUsableLBA = LE_64((vs >> bs) - 1);
1536 		gpt.efi_gpt_PartitionEntryLBA = LE_64(2ULL);
1537 		gpt.efi_gpt_NumberOfPartitionEntries = LE_32(1);
1538 		gpt.efi_gpt_SizeOfPartitionEntry =
1539 		    LE_32(sizeof (efi_gpe_t));
1540 		CRC32(crc, &gpe, sizeof (gpe), -1U, crc32_table);
1541 		gpt.efi_gpt_PartitionEntryArrayCRC32 = LE_32(~crc);
1542 		CRC32(crc, &gpt, EFI_HEADER_SIZE, -1U, crc32_table);
1543 		gpt.efi_gpt_HeaderCRC32 = LE_32(~crc);
1544 		if (ddi_copyout(&gpt, ptr, MIN(sizeof (gpt), length),
1545 		    flag))
1546 			return (SET_ERROR(EFAULT));
1547 		ptr += sizeof (gpt);
1548 		length -= sizeof (gpt);
1549 	}
1550 	if (length > 0 && ddi_copyout(&gpe, ptr, MIN(sizeof (gpe),
1551 	    length), flag))
1552 		return (SET_ERROR(EFAULT));
1553 	return (0);
1554 }
1555 
1556 /*
1557  * BEGIN entry points to allow external callers access to the volume.
1558  */
1559 /*
1560  * Return the volume parameters needed for access from an external caller.
1561  * These values are invariant as long as the volume is held open.
1562  */
1563 int
1564 zvol_get_volume_params(minor_t minor, uint64_t *blksize,
1565     uint64_t *max_xfer_len, void **minor_hdl, void **objset_hdl, void **zil_hdl,
1566     void **rl_hdl, void **dnode_hdl)
1567 {
1568 	zvol_state_t *zv;
1569 
1570 	zv = zfsdev_get_soft_state(minor, ZSST_ZVOL);
1571 	if (zv == NULL)
1572 		return (SET_ERROR(ENXIO));
1573 	if (zv->zv_flags & ZVOL_DUMPIFIED)
1574 		return (SET_ERROR(ENXIO));
1575 
1576 	ASSERT(blksize && max_xfer_len && minor_hdl &&
1577 	    objset_hdl && zil_hdl && rl_hdl && dnode_hdl);
1578 
1579 	*blksize = zv->zv_volblocksize;
1580 	*max_xfer_len = (uint64_t)zvol_maxphys;
1581 	*minor_hdl = zv;
1582 	*objset_hdl = zv->zv_objset;
1583 	*zil_hdl = zv->zv_zilog;
1584 	*rl_hdl = &zv->zv_rangelock;
1585 	*dnode_hdl = zv->zv_dn;
1586 	return (0);
1587 }
1588 
1589 /*
1590  * Return the current volume size to an external caller.
1591  * The size can change while the volume is open.
1592  */
1593 uint64_t
1594 zvol_get_volume_size(void *minor_hdl)
1595 {
1596 	zvol_state_t *zv = minor_hdl;
1597 
1598 	return (zv->zv_volsize);
1599 }
1600 
1601 /*
1602  * Return the current WCE setting to an external caller.
1603  * The WCE setting can change while the volume is open.
1604  */
1605 int
1606 zvol_get_volume_wce(void *minor_hdl)
1607 {
1608 	zvol_state_t *zv = minor_hdl;
1609 
1610 	return ((zv->zv_flags & ZVOL_WCE) ? 1 : 0);
1611 }
1612 
1613 /*
1614  * Entry point for external callers to zvol_log_write
1615  */
1616 void
1617 zvol_log_write_minor(void *minor_hdl, dmu_tx_t *tx, offset_t off, ssize_t resid,
1618     boolean_t sync)
1619 {
1620 	zvol_state_t *zv = minor_hdl;
1621 
1622 	zvol_log_write(zv, tx, off, resid, sync);
1623 }
1624 /*
1625  * END entry points to allow external callers access to the volume.
1626  */
1627 
1628 /*
1629  * Log a DKIOCFREE/free-long-range to the ZIL with TX_TRUNCATE.
1630  */
1631 static void
1632 zvol_log_truncate(zvol_state_t *zv, dmu_tx_t *tx, uint64_t off, uint64_t len,
1633     boolean_t sync)
1634 {
1635 	itx_t *itx;
1636 	lr_truncate_t *lr;
1637 	zilog_t *zilog = zv->zv_zilog;
1638 
1639 	if (zil_replaying(zilog, tx))
1640 		return;
1641 
1642 	itx = zil_itx_create(TX_TRUNCATE, sizeof (*lr));
1643 	lr = (lr_truncate_t *)&itx->itx_lr;
1644 	lr->lr_foid = ZVOL_OBJ;
1645 	lr->lr_offset = off;
1646 	lr->lr_length = len;
1647 
1648 	itx->itx_sync = sync;
1649 	zil_itx_assign(zilog, itx, tx);
1650 }
1651 
1652 /*
1653  * Dirtbag ioctls to support mkfs(1M) for UFS filesystems.  See dkio(7I).
1654  * Also a dirtbag dkio ioctl for unmap/free-block functionality.
1655  */
1656 /*ARGSUSED*/
1657 int
1658 zvol_ioctl(dev_t dev, int cmd, intptr_t arg, int flag, cred_t *cr, int *rvalp)
1659 {
1660 	zvol_state_t *zv;
1661 	struct dk_callback *dkc;
1662 	int i, error = 0;
1663 	locked_range_t *lr;
1664 
1665 	mutex_enter(&zfsdev_state_lock);
1666 
1667 	zv = zfsdev_get_soft_state(getminor(dev), ZSST_ZVOL);
1668 
1669 	if (zv == NULL) {
1670 		mutex_exit(&zfsdev_state_lock);
1671 		return (SET_ERROR(ENXIO));
1672 	}
1673 	ASSERT(zv->zv_total_opens > 0);
1674 
1675 	switch (cmd) {
1676 
1677 	case DKIOCINFO:
1678 	{
1679 		struct dk_cinfo dki;
1680 
1681 		bzero(&dki, sizeof (dki));
1682 		(void) strcpy(dki.dki_cname, "zvol");
1683 		(void) strcpy(dki.dki_dname, "zvol");
1684 		dki.dki_ctype = DKC_UNKNOWN;
1685 		dki.dki_unit = getminor(dev);
1686 		dki.dki_maxtransfer =
1687 		    1 << (SPA_OLD_MAXBLOCKSHIFT - zv->zv_min_bs);
1688 		mutex_exit(&zfsdev_state_lock);
1689 		if (ddi_copyout(&dki, (void *)arg, sizeof (dki), flag))
1690 			error = SET_ERROR(EFAULT);
1691 		return (error);
1692 	}
1693 
1694 	case DKIOCGMEDIAINFO:
1695 	{
1696 		struct dk_minfo dkm;
1697 
1698 		bzero(&dkm, sizeof (dkm));
1699 		dkm.dki_lbsize = 1U << zv->zv_min_bs;
1700 		dkm.dki_capacity = zv->zv_volsize >> zv->zv_min_bs;
1701 		dkm.dki_media_type = DK_UNKNOWN;
1702 		mutex_exit(&zfsdev_state_lock);
1703 		if (ddi_copyout(&dkm, (void *)arg, sizeof (dkm), flag))
1704 			error = SET_ERROR(EFAULT);
1705 		return (error);
1706 	}
1707 
1708 	case DKIOCGMEDIAINFOEXT:
1709 	{
1710 		struct dk_minfo_ext dkmext;
1711 
1712 		bzero(&dkmext, sizeof (dkmext));
1713 		dkmext.dki_lbsize = 1U << zv->zv_min_bs;
1714 		dkmext.dki_pbsize = zv->zv_volblocksize;
1715 		dkmext.dki_capacity = zv->zv_volsize >> zv->zv_min_bs;
1716 		dkmext.dki_media_type = DK_UNKNOWN;
1717 		mutex_exit(&zfsdev_state_lock);
1718 		if (ddi_copyout(&dkmext, (void *)arg, sizeof (dkmext), flag))
1719 			error = SET_ERROR(EFAULT);
1720 		return (error);
1721 	}
1722 
1723 	case DKIOCGETEFI:
1724 	{
1725 		uint64_t vs = zv->zv_volsize;
1726 		uint8_t bs = zv->zv_min_bs;
1727 
1728 		mutex_exit(&zfsdev_state_lock);
1729 		error = zvol_getefi((void *)arg, flag, vs, bs);
1730 		return (error);
1731 	}
1732 
1733 	case DKIOCFLUSHWRITECACHE:
1734 		dkc = (struct dk_callback *)arg;
1735 		mutex_exit(&zfsdev_state_lock);
1736 
1737 		smt_begin_unsafe();
1738 
1739 		zil_commit(zv->zv_zilog, ZVOL_OBJ);
1740 		if ((flag & FKIOCTL) && dkc != NULL && dkc->dkc_callback) {
1741 			(*dkc->dkc_callback)(dkc->dkc_cookie, error);
1742 			error = 0;
1743 		}
1744 
1745 		smt_end_unsafe();
1746 
1747 		return (error);
1748 
1749 	case DKIOCGETWCE:
1750 	{
1751 		int wce = (zv->zv_flags & ZVOL_WCE) ? 1 : 0;
1752 		if (ddi_copyout(&wce, (void *)arg, sizeof (int),
1753 		    flag))
1754 			error = SET_ERROR(EFAULT);
1755 		break;
1756 	}
1757 	case DKIOCSETWCE:
1758 	{
1759 		int wce;
1760 		if (ddi_copyin((void *)arg, &wce, sizeof (int),
1761 		    flag)) {
1762 			error = SET_ERROR(EFAULT);
1763 			break;
1764 		}
1765 		if (wce) {
1766 			zv->zv_flags |= ZVOL_WCE;
1767 			mutex_exit(&zfsdev_state_lock);
1768 		} else {
1769 			zv->zv_flags &= ~ZVOL_WCE;
1770 			mutex_exit(&zfsdev_state_lock);
1771 			smt_begin_unsafe();
1772 			zil_commit(zv->zv_zilog, ZVOL_OBJ);
1773 			smt_end_unsafe();
1774 		}
1775 		return (0);
1776 	}
1777 
1778 	case DKIOCGGEOM:
1779 	case DKIOCGVTOC:
1780 		/*
1781 		 * commands using these (like prtvtoc) expect ENOTSUP
1782 		 * since we're emulating an EFI label
1783 		 */
1784 		error = SET_ERROR(ENOTSUP);
1785 		break;
1786 
1787 	case DKIOCDUMPINIT:
1788 		lr = rangelock_enter(&zv->zv_rangelock, 0, zv->zv_volsize,
1789 		    RL_WRITER);
1790 		error = zvol_dumpify(zv);
1791 		rangelock_exit(lr);
1792 		break;
1793 
1794 	case DKIOCDUMPFINI:
1795 		if (!(zv->zv_flags & ZVOL_DUMPIFIED))
1796 			break;
1797 		lr = rangelock_enter(&zv->zv_rangelock, 0, zv->zv_volsize,
1798 		    RL_WRITER);
1799 		error = zvol_dump_fini(zv);
1800 		rangelock_exit(lr);
1801 		break;
1802 
1803 	case DKIOCFREE:
1804 	{
1805 		dkioc_free_list_t *dfl;
1806 		dmu_tx_t *tx;
1807 
1808 		if (!zvol_unmap_enabled)
1809 			break;
1810 
1811 		if (!(flag & FKIOCTL)) {
1812 			error = dfl_copyin((void *)arg, &dfl, flag, KM_SLEEP);
1813 			if (error != 0)
1814 				break;
1815 		} else {
1816 			dfl = (dkioc_free_list_t *)arg;
1817 			ASSERT3U(dfl->dfl_num_exts, <=, DFL_COPYIN_MAX_EXTS);
1818 			if (dfl->dfl_num_exts > DFL_COPYIN_MAX_EXTS) {
1819 				error = SET_ERROR(EINVAL);
1820 				break;
1821 			}
1822 		}
1823 
1824 		mutex_exit(&zfsdev_state_lock);
1825 
1826 		smt_begin_unsafe();
1827 
1828 		for (int i = 0; i < dfl->dfl_num_exts; i++) {
1829 			uint64_t start = dfl->dfl_exts[i].dfle_start,
1830 			    length = dfl->dfl_exts[i].dfle_length,
1831 			    end = start + length;
1832 
1833 			/*
1834 			 * Apply Postel's Law to length-checking.  If they
1835 			 * overshoot, just blank out until the end, if there's
1836 			 * a need to blank out anything.
1837 			 */
1838 			if (start >= zv->zv_volsize)
1839 				continue;	/* No need to do anything... */
1840 			if (end > zv->zv_volsize) {
1841 				end = DMU_OBJECT_END;
1842 				length = end - start;
1843 			}
1844 
1845 			lr = rangelock_enter(&zv->zv_rangelock, start, length,
1846 			    RL_WRITER);
1847 			tx = dmu_tx_create(zv->zv_objset);
1848 			error = dmu_tx_assign(tx, TXG_WAIT);
1849 			if (error != 0) {
1850 				dmu_tx_abort(tx);
1851 			} else {
1852 				zvol_log_truncate(zv, tx, start, length,
1853 				    B_TRUE);
1854 				dmu_tx_commit(tx);
1855 				error = dmu_free_long_range(zv->zv_objset,
1856 				    ZVOL_OBJ, start, length);
1857 			}
1858 
1859 			rangelock_exit(lr);
1860 
1861 			if (error != 0)
1862 				break;
1863 		}
1864 
1865 		/*
1866 		 * If the write-cache is disabled, 'sync' property
1867 		 * is set to 'always', or if the caller is asking for
1868 		 * a synchronous free, commit this operation to the zil.
1869 		 * This will sync any previous uncommitted writes to the
1870 		 * zvol object.
1871 		 * Can be overridden by the zvol_unmap_sync_enabled tunable.
1872 		 */
1873 		if ((error == 0) && zvol_unmap_sync_enabled &&
1874 		    (!(zv->zv_flags & ZVOL_WCE) ||
1875 		    (zv->zv_objset->os_sync == ZFS_SYNC_ALWAYS) ||
1876 		    (dfl->dfl_flags & DF_WAIT_SYNC))) {
1877 			zil_commit(zv->zv_zilog, ZVOL_OBJ);
1878 		}
1879 
1880 		if (!(flag & FKIOCTL))
1881 			dfl_free(dfl);
1882 
1883 		smt_end_unsafe();
1884 
1885 		return (error);
1886 	}
1887 
1888 	case DKIOC_CANFREE:
1889 		i = zvol_unmap_enabled ? 1 : 0;
1890 		if (ddi_copyout(&i, (void *)arg, sizeof (int), flag) != 0) {
1891 			error = EFAULT;
1892 		} else {
1893 			error = 0;
1894 		}
1895 		break;
1896 
1897 	default:
1898 		error = SET_ERROR(ENOTTY);
1899 		break;
1900 
1901 	}
1902 	mutex_exit(&zfsdev_state_lock);
1903 	return (error);
1904 }
1905 
1906 int
1907 zvol_busy(void)
1908 {
1909 	return (zvol_minors != 0);
1910 }
1911 
1912 void
1913 zvol_init(void)
1914 {
1915 	VERIFY(ddi_soft_state_init(&zfsdev_state, sizeof (zfs_soft_state_t),
1916 	    1) == 0);
1917 	mutex_init(&zfsdev_state_lock, NULL, MUTEX_DEFAULT, NULL);
1918 }
1919 
1920 void
1921 zvol_fini(void)
1922 {
1923 	mutex_destroy(&zfsdev_state_lock);
1924 	ddi_soft_state_fini(&zfsdev_state);
1925 }
1926 
1927 /*ARGSUSED*/
1928 static int
1929 zfs_mvdev_dump_feature_check(void *arg, dmu_tx_t *tx)
1930 {
1931 	spa_t *spa = dmu_tx_pool(tx)->dp_spa;
1932 
1933 	if (spa_feature_is_active(spa, SPA_FEATURE_MULTI_VDEV_CRASH_DUMP))
1934 		return (1);
1935 	return (0);
1936 }
1937 
1938 /*ARGSUSED*/
1939 static void
1940 zfs_mvdev_dump_activate_feature_sync(void *arg, dmu_tx_t *tx)
1941 {
1942 	spa_t *spa = dmu_tx_pool(tx)->dp_spa;
1943 
1944 	spa_feature_incr(spa, SPA_FEATURE_MULTI_VDEV_CRASH_DUMP, tx);
1945 }
1946 
1947 static int
1948 zvol_dump_init(zvol_state_t *zv, boolean_t resize)
1949 {
1950 	dmu_tx_t *tx;
1951 	int error;
1952 	objset_t *os = zv->zv_objset;
1953 	spa_t *spa = dmu_objset_spa(os);
1954 	vdev_t *vd = spa->spa_root_vdev;
1955 	nvlist_t *nv = NULL;
1956 	uint64_t version = spa_version(spa);
1957 	uint64_t checksum, compress, refresrv, vbs, dedup;
1958 
1959 	ASSERT(MUTEX_HELD(&zfsdev_state_lock));
1960 	ASSERT(vd->vdev_ops == &vdev_root_ops);
1961 
1962 	error = dmu_free_long_range(zv->zv_objset, ZVOL_OBJ, 0,
1963 	    DMU_OBJECT_END);
1964 	if (error != 0)
1965 		return (error);
1966 	/* wait for dmu_free_long_range to actually free the blocks */
1967 	txg_wait_synced(dmu_objset_pool(zv->zv_objset), 0);
1968 
1969 	/*
1970 	 * If the pool on which the dump device is being initialized has more
1971 	 * than one child vdev, check that the MULTI_VDEV_CRASH_DUMP feature is
1972 	 * enabled.  If so, bump that feature's counter to indicate that the
1973 	 * feature is active. We also check the vdev type to handle the
1974 	 * following case:
1975 	 *   # zpool create test raidz disk1 disk2 disk3
1976 	 *   Now have spa_root_vdev->vdev_children == 1 (the raidz vdev),
1977 	 *   the raidz vdev itself has 3 children.
1978 	 */
1979 	if (vd->vdev_children > 1 || vd->vdev_ops == &vdev_raidz_ops) {
1980 		if (!spa_feature_is_enabled(spa,
1981 		    SPA_FEATURE_MULTI_VDEV_CRASH_DUMP))
1982 			return (SET_ERROR(ENOTSUP));
1983 		(void) dsl_sync_task(spa_name(spa),
1984 		    zfs_mvdev_dump_feature_check,
1985 		    zfs_mvdev_dump_activate_feature_sync, NULL,
1986 		    2, ZFS_SPACE_CHECK_RESERVED);
1987 	}
1988 
1989 	if (!resize) {
1990 		error = dsl_prop_get_integer(zv->zv_name,
1991 		    zfs_prop_to_name(ZFS_PROP_COMPRESSION), &compress, NULL);
1992 		if (error == 0) {
1993 			error = dsl_prop_get_integer(zv->zv_name,
1994 			    zfs_prop_to_name(ZFS_PROP_CHECKSUM), &checksum,
1995 			    NULL);
1996 		}
1997 		if (error == 0) {
1998 			error = dsl_prop_get_integer(zv->zv_name,
1999 			    zfs_prop_to_name(ZFS_PROP_REFRESERVATION),
2000 			    &refresrv, NULL);
2001 		}
2002 		if (error == 0) {
2003 			error = dsl_prop_get_integer(zv->zv_name,
2004 			    zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE), &vbs,
2005 			    NULL);
2006 		}
2007 		if (version >= SPA_VERSION_DEDUP && error == 0) {
2008 			error = dsl_prop_get_integer(zv->zv_name,
2009 			    zfs_prop_to_name(ZFS_PROP_DEDUP), &dedup, NULL);
2010 		}
2011 	}
2012 	if (error != 0)
2013 		return (error);
2014 
2015 	tx = dmu_tx_create(os);
2016 	dmu_tx_hold_zap(tx, ZVOL_ZAP_OBJ, TRUE, NULL);
2017 	dmu_tx_hold_bonus(tx, ZVOL_OBJ);
2018 	error = dmu_tx_assign(tx, TXG_WAIT);
2019 	if (error != 0) {
2020 		dmu_tx_abort(tx);
2021 		return (error);
2022 	}
2023 
2024 	/*
2025 	 * If we are resizing the dump device then we only need to
2026 	 * update the refreservation to match the newly updated
2027 	 * zvolsize. Otherwise, we save off the original state of the
2028 	 * zvol so that we can restore them if the zvol is ever undumpified.
2029 	 */
2030 	if (resize) {
2031 		error = zap_update(os, ZVOL_ZAP_OBJ,
2032 		    zfs_prop_to_name(ZFS_PROP_REFRESERVATION), 8, 1,
2033 		    &zv->zv_volsize, tx);
2034 	} else {
2035 		error = zap_update(os, ZVOL_ZAP_OBJ,
2036 		    zfs_prop_to_name(ZFS_PROP_COMPRESSION), 8, 1,
2037 		    &compress, tx);
2038 		if (error == 0) {
2039 			error = zap_update(os, ZVOL_ZAP_OBJ,
2040 			    zfs_prop_to_name(ZFS_PROP_CHECKSUM), 8, 1,
2041 			    &checksum, tx);
2042 		}
2043 		if (error == 0) {
2044 			error = zap_update(os, ZVOL_ZAP_OBJ,
2045 			    zfs_prop_to_name(ZFS_PROP_REFRESERVATION), 8, 1,
2046 			    &refresrv, tx);
2047 		}
2048 		if (error == 0) {
2049 			error = zap_update(os, ZVOL_ZAP_OBJ,
2050 			    zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE), 8, 1,
2051 			    &vbs, tx);
2052 		}
2053 		if (error == 0) {
2054 			error = dmu_object_set_blocksize(
2055 			    os, ZVOL_OBJ, SPA_OLD_MAXBLOCKSIZE, 0, tx);
2056 		}
2057 		if (version >= SPA_VERSION_DEDUP && error == 0) {
2058 			error = zap_update(os, ZVOL_ZAP_OBJ,
2059 			    zfs_prop_to_name(ZFS_PROP_DEDUP), 8, 1,
2060 			    &dedup, tx);
2061 		}
2062 		if (error == 0)
2063 			zv->zv_volblocksize = SPA_OLD_MAXBLOCKSIZE;
2064 	}
2065 	dmu_tx_commit(tx);
2066 
2067 	/*
2068 	 * We only need update the zvol's property if we are initializing
2069 	 * the dump area for the first time.
2070 	 */
2071 	if (error == 0 && !resize) {
2072 		/*
2073 		 * If MULTI_VDEV_CRASH_DUMP is active, use the NOPARITY checksum
2074 		 * function.  Otherwise, use the old default -- OFF.
2075 		 */
2076 		checksum = spa_feature_is_active(spa,
2077 		    SPA_FEATURE_MULTI_VDEV_CRASH_DUMP) ? ZIO_CHECKSUM_NOPARITY :
2078 		    ZIO_CHECKSUM_OFF;
2079 
2080 		VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, KM_SLEEP) == 0);
2081 		VERIFY(nvlist_add_uint64(nv,
2082 		    zfs_prop_to_name(ZFS_PROP_REFRESERVATION), 0) == 0);
2083 		VERIFY(nvlist_add_uint64(nv,
2084 		    zfs_prop_to_name(ZFS_PROP_COMPRESSION),
2085 		    ZIO_COMPRESS_OFF) == 0);
2086 		VERIFY(nvlist_add_uint64(nv,
2087 		    zfs_prop_to_name(ZFS_PROP_CHECKSUM),
2088 		    checksum) == 0);
2089 		if (version >= SPA_VERSION_DEDUP) {
2090 			VERIFY(nvlist_add_uint64(nv,
2091 			    zfs_prop_to_name(ZFS_PROP_DEDUP),
2092 			    ZIO_CHECKSUM_OFF) == 0);
2093 		}
2094 
2095 		error = zfs_set_prop_nvlist(zv->zv_name, ZPROP_SRC_LOCAL,
2096 		    nv, NULL);
2097 		nvlist_free(nv);
2098 	}
2099 
2100 	/* Allocate the space for the dump */
2101 	if (error == 0)
2102 		error = zvol_prealloc(zv);
2103 	return (error);
2104 }
2105 
2106 static int
2107 zvol_dumpify(zvol_state_t *zv)
2108 {
2109 	int error = 0;
2110 	uint64_t dumpsize = 0;
2111 	dmu_tx_t *tx;
2112 	objset_t *os = zv->zv_objset;
2113 
2114 	if (zv->zv_flags & ZVOL_RDONLY)
2115 		return (SET_ERROR(EROFS));
2116 
2117 	if (os->os_encrypted)
2118 		return (SET_ERROR(ENOTSUP));
2119 
2120 	if (zap_lookup(zv->zv_objset, ZVOL_ZAP_OBJ, ZVOL_DUMPSIZE,
2121 	    8, 1, &dumpsize) != 0 || dumpsize != zv->zv_volsize) {
2122 		boolean_t resize = (dumpsize > 0);
2123 
2124 		if ((error = zvol_dump_init(zv, resize)) != 0) {
2125 			(void) zvol_dump_fini(zv);
2126 			return (error);
2127 		}
2128 	}
2129 
2130 	/*
2131 	 * Build up our lba mapping.
2132 	 */
2133 	error = zvol_get_lbas(zv);
2134 	if (error) {
2135 		(void) zvol_dump_fini(zv);
2136 		return (error);
2137 	}
2138 
2139 	tx = dmu_tx_create(os);
2140 	dmu_tx_hold_zap(tx, ZVOL_ZAP_OBJ, TRUE, NULL);
2141 	error = dmu_tx_assign(tx, TXG_WAIT);
2142 	if (error) {
2143 		dmu_tx_abort(tx);
2144 		(void) zvol_dump_fini(zv);
2145 		return (error);
2146 	}
2147 
2148 	zv->zv_flags |= ZVOL_DUMPIFIED;
2149 	error = zap_update(os, ZVOL_ZAP_OBJ, ZVOL_DUMPSIZE, 8, 1,
2150 	    &zv->zv_volsize, tx);
2151 	dmu_tx_commit(tx);
2152 
2153 	if (error) {
2154 		(void) zvol_dump_fini(zv);
2155 		return (error);
2156 	}
2157 
2158 	txg_wait_synced(dmu_objset_pool(os), 0);
2159 	return (0);
2160 }
2161 
2162 static int
2163 zvol_dump_fini(zvol_state_t *zv)
2164 {
2165 	dmu_tx_t *tx;
2166 	objset_t *os = zv->zv_objset;
2167 	nvlist_t *nv;
2168 	int error = 0;
2169 	uint64_t checksum, compress, refresrv, vbs, dedup;
2170 	uint64_t version = spa_version(dmu_objset_spa(zv->zv_objset));
2171 
2172 	/*
2173 	 * Attempt to restore the zvol back to its pre-dumpified state.
2174 	 * This is a best-effort attempt as it's possible that not all
2175 	 * of these properties were initialized during the dumpify process
2176 	 * (i.e. error during zvol_dump_init).
2177 	 */
2178 
2179 	tx = dmu_tx_create(os);
2180 	dmu_tx_hold_zap(tx, ZVOL_ZAP_OBJ, TRUE, NULL);
2181 	error = dmu_tx_assign(tx, TXG_WAIT);
2182 	if (error) {
2183 		dmu_tx_abort(tx);
2184 		return (error);
2185 	}
2186 	(void) zap_remove(os, ZVOL_ZAP_OBJ, ZVOL_DUMPSIZE, tx);
2187 	dmu_tx_commit(tx);
2188 
2189 	(void) zap_lookup(zv->zv_objset, ZVOL_ZAP_OBJ,
2190 	    zfs_prop_to_name(ZFS_PROP_CHECKSUM), 8, 1, &checksum);
2191 	(void) zap_lookup(zv->zv_objset, ZVOL_ZAP_OBJ,
2192 	    zfs_prop_to_name(ZFS_PROP_COMPRESSION), 8, 1, &compress);
2193 	(void) zap_lookup(zv->zv_objset, ZVOL_ZAP_OBJ,
2194 	    zfs_prop_to_name(ZFS_PROP_REFRESERVATION), 8, 1, &refresrv);
2195 	(void) zap_lookup(zv->zv_objset, ZVOL_ZAP_OBJ,
2196 	    zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE), 8, 1, &vbs);
2197 
2198 	VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, KM_SLEEP) == 0);
2199 	(void) nvlist_add_uint64(nv,
2200 	    zfs_prop_to_name(ZFS_PROP_CHECKSUM), checksum);
2201 	(void) nvlist_add_uint64(nv,
2202 	    zfs_prop_to_name(ZFS_PROP_COMPRESSION), compress);
2203 	(void) nvlist_add_uint64(nv,
2204 	    zfs_prop_to_name(ZFS_PROP_REFRESERVATION), refresrv);
2205 	if (version >= SPA_VERSION_DEDUP &&
2206 	    zap_lookup(zv->zv_objset, ZVOL_ZAP_OBJ,
2207 	    zfs_prop_to_name(ZFS_PROP_DEDUP), 8, 1, &dedup) == 0) {
2208 		(void) nvlist_add_uint64(nv,
2209 		    zfs_prop_to_name(ZFS_PROP_DEDUP), dedup);
2210 	}
2211 	(void) zfs_set_prop_nvlist(zv->zv_name, ZPROP_SRC_LOCAL,
2212 	    nv, NULL);
2213 	nvlist_free(nv);
2214 
2215 	zvol_free_extents(zv);
2216 	zv->zv_flags &= ~ZVOL_DUMPIFIED;
2217 	(void) dmu_free_long_range(os, ZVOL_OBJ, 0, DMU_OBJECT_END);
2218 	/* wait for dmu_free_long_range to actually free the blocks */
2219 	txg_wait_synced(dmu_objset_pool(zv->zv_objset), 0);
2220 	tx = dmu_tx_create(os);
2221 	dmu_tx_hold_bonus(tx, ZVOL_OBJ);
2222 	error = dmu_tx_assign(tx, TXG_WAIT);
2223 	if (error) {
2224 		dmu_tx_abort(tx);
2225 		return (error);
2226 	}
2227 	if (dmu_object_set_blocksize(os, ZVOL_OBJ, vbs, 0, tx) == 0)
2228 		zv->zv_volblocksize = vbs;
2229 	dmu_tx_commit(tx);
2230 
2231 	return (0);
2232 }
2233