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 https://opensource.org/licenses/CDDL-1.0.
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) 2008-2010 Lawrence Livermore National Security, LLC.
23 * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
24 * Rewritten for Linux by Brian Behlendorf <behlendorf1@llnl.gov>.
25 * LLNL-CODE-403049.
26 *
27 * ZFS volume emulation driver.
28 *
29 * Makes a DMU object look like a volume of arbitrary size, up to 2^64 bytes.
30 * Volumes are accessed through the symbolic links named:
31 *
32 * /dev/<pool_name>/<dataset_name>
33 *
34 * Volumes are persistent through reboot and module load. No user command
35 * needs to be run before opening and using a device.
36 *
37 * Copyright 2014 Nexenta Systems, Inc. All rights reserved.
38 * Copyright (c) 2016 Actifio, Inc. All rights reserved.
39 * Copyright (c) 2012, 2019 by Delphix. All rights reserved.
40 * Copyright (c) 2024, Klara, Inc.
41 */
42
43 /*
44 * Note on locking of zvol state structures.
45 *
46 * These structures are used to maintain internal state used to emulate block
47 * devices on top of zvols. In particular, management of device minor number
48 * operations - create, remove, rename, and set_snapdev - involves access to
49 * these structures. The zvol_state_lock is primarily used to protect the
50 * zvol_state_list. The zv->zv_state_lock is used to protect the contents
51 * of the zvol_state_t structures, as well as to make sure that when the
52 * time comes to remove the structure from the list, it is not in use, and
53 * therefore, it can be taken off zvol_state_list and freed.
54 *
55 * The zv_suspend_lock was introduced to allow for suspending I/O to a zvol,
56 * e.g. for the duration of receive and rollback operations. This lock can be
57 * held for significant periods of time. Given that it is undesirable to hold
58 * mutexes for long periods of time, the following lock ordering applies:
59 * - take zvol_state_lock if necessary, to protect zvol_state_list
60 * - take zv_suspend_lock if necessary, by the code path in question
61 * - take zv_state_lock to protect zvol_state_t
62 *
63 * The minor operations are issued to spa->spa_zvol_taskq queues, that are
64 * single-threaded (to preserve order of minor operations), and are executed
65 * through the zvol_task_cb that dispatches the specific operations. Therefore,
66 * these operations are serialized per pool. Consequently, we can be certain
67 * that for a given zvol, there is only one operation at a time in progress.
68 * That is why one can be sure that first, zvol_state_t for a given zvol is
69 * allocated and placed on zvol_state_list, and then other minor operations
70 * for this zvol are going to proceed in the order of issue.
71 *
72 */
73
74 #include <sys/dataset_kstats.h>
75 #include <sys/dbuf.h>
76 #include <sys/dmu_traverse.h>
77 #include <sys/dsl_dataset.h>
78 #include <sys/dsl_prop.h>
79 #include <sys/dsl_dir.h>
80 #include <sys/zap.h>
81 #include <sys/zfeature.h>
82 #include <sys/zil_impl.h>
83 #include <sys/dmu_tx.h>
84 #include <sys/zio.h>
85 #include <sys/zfs_rlock.h>
86 #include <sys/spa_impl.h>
87 #include <sys/zvol.h>
88 #include <sys/zvol_impl.h>
89
90 unsigned int zvol_inhibit_dev = 0;
91 unsigned int zvol_volmode = ZFS_VOLMODE_GEOM;
92
93 struct hlist_head *zvol_htable;
94 static list_t zvol_state_list;
95 krwlock_t zvol_state_lock;
96
97 typedef enum {
98 ZVOL_ASYNC_REMOVE_MINORS,
99 ZVOL_ASYNC_RENAME_MINORS,
100 ZVOL_ASYNC_SET_SNAPDEV,
101 ZVOL_ASYNC_SET_VOLMODE,
102 ZVOL_ASYNC_MAX
103 } zvol_async_op_t;
104
105 typedef struct {
106 zvol_async_op_t op;
107 char name1[MAXNAMELEN];
108 char name2[MAXNAMELEN];
109 uint64_t value;
110 } zvol_task_t;
111
112 uint64_t
zvol_name_hash(const char * name)113 zvol_name_hash(const char *name)
114 {
115 uint64_t crc = -1ULL;
116 ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY);
117 for (const uint8_t *p = (const uint8_t *)name; *p != 0; p++)
118 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (*p)) & 0xFF];
119 return (crc);
120 }
121
122 /*
123 * Find a zvol_state_t given the name and hash generated by zvol_name_hash.
124 * If found, return with zv_suspend_lock and zv_state_lock taken, otherwise,
125 * return (NULL) without the taking locks. The zv_suspend_lock is always taken
126 * before zv_state_lock. The mode argument indicates the mode (including none)
127 * for zv_suspend_lock to be taken.
128 */
129 zvol_state_t *
zvol_find_by_name_hash(const char * name,uint64_t hash,int mode)130 zvol_find_by_name_hash(const char *name, uint64_t hash, int mode)
131 {
132 zvol_state_t *zv;
133 struct hlist_node *p = NULL;
134
135 rw_enter(&zvol_state_lock, RW_READER);
136 hlist_for_each(p, ZVOL_HT_HEAD(hash)) {
137 zv = hlist_entry(p, zvol_state_t, zv_hlink);
138 mutex_enter(&zv->zv_state_lock);
139 if (zv->zv_hash == hash && strcmp(zv->zv_name, name) == 0) {
140 /*
141 * this is the right zvol, take the locks in the
142 * right order
143 */
144 if (mode != RW_NONE &&
145 !rw_tryenter(&zv->zv_suspend_lock, mode)) {
146 mutex_exit(&zv->zv_state_lock);
147 rw_enter(&zv->zv_suspend_lock, mode);
148 mutex_enter(&zv->zv_state_lock);
149 /*
150 * zvol cannot be renamed as we continue
151 * to hold zvol_state_lock
152 */
153 ASSERT(zv->zv_hash == hash &&
154 strcmp(zv->zv_name, name) == 0);
155 }
156 rw_exit(&zvol_state_lock);
157 return (zv);
158 }
159 mutex_exit(&zv->zv_state_lock);
160 }
161 rw_exit(&zvol_state_lock);
162
163 return (NULL);
164 }
165
166 /*
167 * Find a zvol_state_t given the name.
168 * If found, return with zv_suspend_lock and zv_state_lock taken, otherwise,
169 * return (NULL) without the taking locks. The zv_suspend_lock is always taken
170 * before zv_state_lock. The mode argument indicates the mode (including none)
171 * for zv_suspend_lock to be taken.
172 */
173 static zvol_state_t *
zvol_find_by_name(const char * name,int mode)174 zvol_find_by_name(const char *name, int mode)
175 {
176 return (zvol_find_by_name_hash(name, zvol_name_hash(name), mode));
177 }
178
179 /*
180 * ZFS_IOC_CREATE callback handles dmu zvol and zap object creation.
181 */
182 void
zvol_create_cb(objset_t * os,void * arg,cred_t * cr,dmu_tx_t * tx)183 zvol_create_cb(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx)
184 {
185 zfs_creat_t *zct = arg;
186 nvlist_t *nvprops = zct->zct_props;
187 int error;
188 uint64_t volblocksize, volsize;
189
190 VERIFY(nvlist_lookup_uint64(nvprops,
191 zfs_prop_to_name(ZFS_PROP_VOLSIZE), &volsize) == 0);
192 if (nvlist_lookup_uint64(nvprops,
193 zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE), &volblocksize) != 0)
194 volblocksize = zfs_prop_default_numeric(ZFS_PROP_VOLBLOCKSIZE);
195
196 /*
197 * These properties must be removed from the list so the generic
198 * property setting step won't apply to them.
199 */
200 VERIFY(nvlist_remove_all(nvprops,
201 zfs_prop_to_name(ZFS_PROP_VOLSIZE)) == 0);
202 (void) nvlist_remove_all(nvprops,
203 zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE));
204
205 error = dmu_object_claim(os, ZVOL_OBJ, DMU_OT_ZVOL, volblocksize,
206 DMU_OT_NONE, 0, tx);
207 ASSERT(error == 0);
208
209 error = zap_create_claim(os, ZVOL_ZAP_OBJ, DMU_OT_ZVOL_PROP,
210 DMU_OT_NONE, 0, tx);
211 ASSERT(error == 0);
212
213 error = zap_update(os, ZVOL_ZAP_OBJ, "size", 8, 1, &volsize, tx);
214 ASSERT(error == 0);
215 }
216
217 /*
218 * ZFS_IOC_OBJSET_STATS entry point.
219 */
220 int
zvol_get_stats(objset_t * os,nvlist_t * nv)221 zvol_get_stats(objset_t *os, nvlist_t *nv)
222 {
223 int error;
224 dmu_object_info_t *doi;
225 uint64_t val;
226
227 error = zap_lookup(os, ZVOL_ZAP_OBJ, "size", 8, 1, &val);
228 if (error)
229 return (SET_ERROR(error));
230
231 dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_VOLSIZE, val);
232 doi = kmem_alloc(sizeof (dmu_object_info_t), KM_SLEEP);
233 error = dmu_object_info(os, ZVOL_OBJ, doi);
234
235 if (error == 0) {
236 dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_VOLBLOCKSIZE,
237 doi->doi_data_block_size);
238 }
239
240 kmem_free(doi, sizeof (dmu_object_info_t));
241
242 return (SET_ERROR(error));
243 }
244
245 /*
246 * Sanity check volume size.
247 */
248 int
zvol_check_volsize(uint64_t volsize,uint64_t blocksize)249 zvol_check_volsize(uint64_t volsize, uint64_t blocksize)
250 {
251 if (volsize == 0)
252 return (SET_ERROR(EINVAL));
253
254 if (volsize % blocksize != 0)
255 return (SET_ERROR(EINVAL));
256
257 #ifdef _ILP32
258 if (volsize - 1 > SPEC_MAXOFFSET_T)
259 return (SET_ERROR(EOVERFLOW));
260 #endif
261 return (0);
262 }
263
264 /*
265 * Ensure the zap is flushed then inform the VFS of the capacity change.
266 */
267 static int
zvol_update_volsize(uint64_t volsize,objset_t * os)268 zvol_update_volsize(uint64_t volsize, objset_t *os)
269 {
270 dmu_tx_t *tx;
271 int error;
272 uint64_t txg;
273
274 tx = dmu_tx_create(os);
275 dmu_tx_hold_zap(tx, ZVOL_ZAP_OBJ, TRUE, NULL);
276 dmu_tx_mark_netfree(tx);
277 error = dmu_tx_assign(tx, TXG_WAIT);
278 if (error) {
279 dmu_tx_abort(tx);
280 return (SET_ERROR(error));
281 }
282 txg = dmu_tx_get_txg(tx);
283
284 error = zap_update(os, ZVOL_ZAP_OBJ, "size", 8, 1,
285 &volsize, tx);
286 dmu_tx_commit(tx);
287
288 txg_wait_synced(dmu_objset_pool(os), txg);
289
290 if (error == 0)
291 error = dmu_free_long_range(os,
292 ZVOL_OBJ, volsize, DMU_OBJECT_END);
293
294 return (error);
295 }
296
297 /*
298 * Set ZFS_PROP_VOLSIZE set entry point. Note that modifying the volume
299 * size will result in a udev "change" event being generated.
300 */
301 int
zvol_set_volsize(const char * name,uint64_t volsize)302 zvol_set_volsize(const char *name, uint64_t volsize)
303 {
304 objset_t *os = NULL;
305 uint64_t readonly;
306 int error;
307 boolean_t owned = B_FALSE;
308
309 error = dsl_prop_get_integer(name,
310 zfs_prop_to_name(ZFS_PROP_READONLY), &readonly, NULL);
311 if (error != 0)
312 return (SET_ERROR(error));
313 if (readonly)
314 return (SET_ERROR(EROFS));
315
316 zvol_state_t *zv = zvol_find_by_name(name, RW_READER);
317
318 ASSERT(zv == NULL || (MUTEX_HELD(&zv->zv_state_lock) &&
319 RW_READ_HELD(&zv->zv_suspend_lock)));
320
321 if (zv == NULL || zv->zv_objset == NULL) {
322 if (zv != NULL)
323 rw_exit(&zv->zv_suspend_lock);
324 if ((error = dmu_objset_own(name, DMU_OST_ZVOL, B_FALSE, B_TRUE,
325 FTAG, &os)) != 0) {
326 if (zv != NULL)
327 mutex_exit(&zv->zv_state_lock);
328 return (SET_ERROR(error));
329 }
330 owned = B_TRUE;
331 if (zv != NULL)
332 zv->zv_objset = os;
333 } else {
334 os = zv->zv_objset;
335 }
336
337 dmu_object_info_t *doi = kmem_alloc(sizeof (*doi), KM_SLEEP);
338
339 if ((error = dmu_object_info(os, ZVOL_OBJ, doi)) ||
340 (error = zvol_check_volsize(volsize, doi->doi_data_block_size)))
341 goto out;
342
343 error = zvol_update_volsize(volsize, os);
344 if (error == 0 && zv != NULL) {
345 zv->zv_volsize = volsize;
346 zv->zv_changed = 1;
347 }
348 out:
349 kmem_free(doi, sizeof (dmu_object_info_t));
350
351 if (owned) {
352 dmu_objset_disown(os, B_TRUE, FTAG);
353 if (zv != NULL)
354 zv->zv_objset = NULL;
355 } else {
356 rw_exit(&zv->zv_suspend_lock);
357 }
358
359 if (zv != NULL)
360 mutex_exit(&zv->zv_state_lock);
361
362 if (error == 0 && zv != NULL)
363 zvol_os_update_volsize(zv, volsize);
364
365 return (SET_ERROR(error));
366 }
367
368 /*
369 * Update volthreading.
370 */
371 int
zvol_set_volthreading(const char * name,boolean_t value)372 zvol_set_volthreading(const char *name, boolean_t value)
373 {
374 zvol_state_t *zv = zvol_find_by_name(name, RW_NONE);
375 if (zv == NULL)
376 return (ENOENT);
377 zv->zv_threading = value;
378 mutex_exit(&zv->zv_state_lock);
379 return (0);
380 }
381
382 /*
383 * Update zvol ro property.
384 */
385 int
zvol_set_ro(const char * name,boolean_t value)386 zvol_set_ro(const char *name, boolean_t value)
387 {
388 zvol_state_t *zv = zvol_find_by_name(name, RW_NONE);
389 if (zv == NULL)
390 return (-1);
391 if (value) {
392 zvol_os_set_disk_ro(zv, 1);
393 zv->zv_flags |= ZVOL_RDONLY;
394 } else {
395 zvol_os_set_disk_ro(zv, 0);
396 zv->zv_flags &= ~ZVOL_RDONLY;
397 }
398 mutex_exit(&zv->zv_state_lock);
399 return (0);
400 }
401
402 /*
403 * Sanity check volume block size.
404 */
405 int
zvol_check_volblocksize(const char * name,uint64_t volblocksize)406 zvol_check_volblocksize(const char *name, uint64_t volblocksize)
407 {
408 /* Record sizes above 128k need the feature to be enabled */
409 if (volblocksize > SPA_OLD_MAXBLOCKSIZE) {
410 spa_t *spa;
411 int error;
412
413 if ((error = spa_open(name, &spa, FTAG)) != 0)
414 return (error);
415
416 if (!spa_feature_is_enabled(spa, SPA_FEATURE_LARGE_BLOCKS)) {
417 spa_close(spa, FTAG);
418 return (SET_ERROR(ENOTSUP));
419 }
420
421 /*
422 * We don't allow setting the property above 1MB,
423 * unless the tunable has been changed.
424 */
425 if (volblocksize > zfs_max_recordsize)
426 return (SET_ERROR(EDOM));
427
428 spa_close(spa, FTAG);
429 }
430
431 if (volblocksize < SPA_MINBLOCKSIZE ||
432 volblocksize > SPA_MAXBLOCKSIZE ||
433 !ISP2(volblocksize))
434 return (SET_ERROR(EDOM));
435
436 return (0);
437 }
438
439 /*
440 * Replay a TX_TRUNCATE ZIL transaction if asked. TX_TRUNCATE is how we
441 * implement DKIOCFREE/free-long-range.
442 */
443 static int
zvol_replay_truncate(void * arg1,void * arg2,boolean_t byteswap)444 zvol_replay_truncate(void *arg1, void *arg2, boolean_t byteswap)
445 {
446 zvol_state_t *zv = arg1;
447 lr_truncate_t *lr = arg2;
448 uint64_t offset, length;
449
450 ASSERT3U(lr->lr_common.lrc_reclen, >=, sizeof (*lr));
451
452 if (byteswap)
453 byteswap_uint64_array(lr, sizeof (*lr));
454
455 offset = lr->lr_offset;
456 length = lr->lr_length;
457
458 dmu_tx_t *tx = dmu_tx_create(zv->zv_objset);
459 dmu_tx_mark_netfree(tx);
460 int error = dmu_tx_assign(tx, TXG_WAIT);
461 if (error != 0) {
462 dmu_tx_abort(tx);
463 } else {
464 (void) zil_replaying(zv->zv_zilog, tx);
465 dmu_tx_commit(tx);
466 error = dmu_free_long_range(zv->zv_objset, ZVOL_OBJ, offset,
467 length);
468 }
469
470 return (error);
471 }
472
473 /*
474 * Replay a TX_WRITE ZIL transaction that didn't get committed
475 * after a system failure
476 */
477 static int
zvol_replay_write(void * arg1,void * arg2,boolean_t byteswap)478 zvol_replay_write(void *arg1, void *arg2, boolean_t byteswap)
479 {
480 zvol_state_t *zv = arg1;
481 lr_write_t *lr = arg2;
482 objset_t *os = zv->zv_objset;
483 char *data = (char *)(lr + 1); /* data follows lr_write_t */
484 uint64_t offset, length;
485 dmu_tx_t *tx;
486 int error;
487
488 ASSERT3U(lr->lr_common.lrc_reclen, >=, sizeof (*lr));
489
490 if (byteswap)
491 byteswap_uint64_array(lr, sizeof (*lr));
492
493 offset = lr->lr_offset;
494 length = lr->lr_length;
495
496 /* If it's a dmu_sync() block, write the whole block */
497 if (lr->lr_common.lrc_reclen == sizeof (lr_write_t)) {
498 uint64_t blocksize = BP_GET_LSIZE(&lr->lr_blkptr);
499 if (length < blocksize) {
500 offset -= offset % blocksize;
501 length = blocksize;
502 }
503 }
504
505 tx = dmu_tx_create(os);
506 dmu_tx_hold_write(tx, ZVOL_OBJ, offset, length);
507 error = dmu_tx_assign(tx, TXG_WAIT);
508 if (error) {
509 dmu_tx_abort(tx);
510 } else {
511 dmu_write(os, ZVOL_OBJ, offset, length, data, tx);
512 (void) zil_replaying(zv->zv_zilog, tx);
513 dmu_tx_commit(tx);
514 }
515
516 return (error);
517 }
518
519 static int
zvol_replay_err(void * arg1,void * arg2,boolean_t byteswap)520 zvol_replay_err(void *arg1, void *arg2, boolean_t byteswap)
521 {
522 (void) arg1, (void) arg2, (void) byteswap;
523 return (SET_ERROR(ENOTSUP));
524 }
525
526 /*
527 * Callback vectors for replaying records.
528 * Only TX_WRITE and TX_TRUNCATE are needed for zvol.
529 */
530 zil_replay_func_t *const zvol_replay_vector[TX_MAX_TYPE] = {
531 zvol_replay_err, /* no such transaction type */
532 zvol_replay_err, /* TX_CREATE */
533 zvol_replay_err, /* TX_MKDIR */
534 zvol_replay_err, /* TX_MKXATTR */
535 zvol_replay_err, /* TX_SYMLINK */
536 zvol_replay_err, /* TX_REMOVE */
537 zvol_replay_err, /* TX_RMDIR */
538 zvol_replay_err, /* TX_LINK */
539 zvol_replay_err, /* TX_RENAME */
540 zvol_replay_write, /* TX_WRITE */
541 zvol_replay_truncate, /* TX_TRUNCATE */
542 zvol_replay_err, /* TX_SETATTR */
543 zvol_replay_err, /* TX_ACL */
544 zvol_replay_err, /* TX_CREATE_ATTR */
545 zvol_replay_err, /* TX_CREATE_ACL_ATTR */
546 zvol_replay_err, /* TX_MKDIR_ACL */
547 zvol_replay_err, /* TX_MKDIR_ATTR */
548 zvol_replay_err, /* TX_MKDIR_ACL_ATTR */
549 zvol_replay_err, /* TX_WRITE2 */
550 zvol_replay_err, /* TX_SETSAXATTR */
551 zvol_replay_err, /* TX_RENAME_EXCHANGE */
552 zvol_replay_err, /* TX_RENAME_WHITEOUT */
553 zvol_replay_err, /* TX_CLONE_RANGE */
554 };
555
556 /*
557 * zvol_log_write() handles synchronous writes using TX_WRITE ZIL transactions.
558 *
559 * We store data in the log buffers if it's small enough.
560 * Otherwise we will later flush the data out via dmu_sync().
561 */
562 static const ssize_t zvol_immediate_write_sz = 32768;
563
564 void
zvol_log_write(zvol_state_t * zv,dmu_tx_t * tx,uint64_t offset,uint64_t size,boolean_t commit)565 zvol_log_write(zvol_state_t *zv, dmu_tx_t *tx, uint64_t offset,
566 uint64_t size, boolean_t commit)
567 {
568 uint32_t blocksize = zv->zv_volblocksize;
569 zilog_t *zilog = zv->zv_zilog;
570 itx_wr_state_t write_state;
571 uint64_t sz = size;
572
573 if (zil_replaying(zilog, tx))
574 return;
575
576 if (zilog->zl_logbias == ZFS_LOGBIAS_THROUGHPUT)
577 write_state = WR_INDIRECT;
578 else if (!spa_has_slogs(zilog->zl_spa) &&
579 size >= blocksize && blocksize > zvol_immediate_write_sz)
580 write_state = WR_INDIRECT;
581 else if (commit)
582 write_state = WR_COPIED;
583 else
584 write_state = WR_NEED_COPY;
585
586 while (size) {
587 itx_t *itx;
588 lr_write_t *lr;
589 itx_wr_state_t wr_state = write_state;
590 ssize_t len = size;
591
592 if (wr_state == WR_COPIED && size > zil_max_copied_data(zilog))
593 wr_state = WR_NEED_COPY;
594 else if (wr_state == WR_INDIRECT)
595 len = MIN(blocksize - P2PHASE(offset, blocksize), size);
596
597 itx = zil_itx_create(TX_WRITE, sizeof (*lr) +
598 (wr_state == WR_COPIED ? len : 0));
599 lr = (lr_write_t *)&itx->itx_lr;
600 if (wr_state == WR_COPIED && dmu_read_by_dnode(zv->zv_dn,
601 offset, len, lr+1, DMU_READ_NO_PREFETCH) != 0) {
602 zil_itx_destroy(itx);
603 itx = zil_itx_create(TX_WRITE, sizeof (*lr));
604 lr = (lr_write_t *)&itx->itx_lr;
605 wr_state = WR_NEED_COPY;
606 }
607
608 itx->itx_wr_state = wr_state;
609 lr->lr_foid = ZVOL_OBJ;
610 lr->lr_offset = offset;
611 lr->lr_length = len;
612 lr->lr_blkoff = 0;
613 BP_ZERO(&lr->lr_blkptr);
614
615 itx->itx_private = zv;
616
617 (void) zil_itx_assign(zilog, itx, tx);
618
619 offset += len;
620 size -= len;
621 }
622
623 if (write_state == WR_COPIED || write_state == WR_NEED_COPY) {
624 dsl_pool_wrlog_count(zilog->zl_dmu_pool, sz, tx->tx_txg);
625 }
626 }
627
628 /*
629 * Log a DKIOCFREE/free-long-range to the ZIL with TX_TRUNCATE.
630 */
631 void
zvol_log_truncate(zvol_state_t * zv,dmu_tx_t * tx,uint64_t off,uint64_t len)632 zvol_log_truncate(zvol_state_t *zv, dmu_tx_t *tx, uint64_t off, uint64_t len)
633 {
634 itx_t *itx;
635 lr_truncate_t *lr;
636 zilog_t *zilog = zv->zv_zilog;
637
638 if (zil_replaying(zilog, tx))
639 return;
640
641 itx = zil_itx_create(TX_TRUNCATE, sizeof (*lr));
642 lr = (lr_truncate_t *)&itx->itx_lr;
643 lr->lr_foid = ZVOL_OBJ;
644 lr->lr_offset = off;
645 lr->lr_length = len;
646
647 zil_itx_assign(zilog, itx, tx);
648 }
649
650
651 static void
zvol_get_done(zgd_t * zgd,int error)652 zvol_get_done(zgd_t *zgd, int error)
653 {
654 (void) error;
655 if (zgd->zgd_db)
656 dmu_buf_rele(zgd->zgd_db, zgd);
657
658 zfs_rangelock_exit(zgd->zgd_lr);
659
660 kmem_free(zgd, sizeof (zgd_t));
661 }
662
663 /*
664 * Get data to generate a TX_WRITE intent log record.
665 */
666 int
zvol_get_data(void * arg,uint64_t arg2,lr_write_t * lr,char * buf,struct lwb * lwb,zio_t * zio)667 zvol_get_data(void *arg, uint64_t arg2, lr_write_t *lr, char *buf,
668 struct lwb *lwb, zio_t *zio)
669 {
670 zvol_state_t *zv = arg;
671 uint64_t offset = lr->lr_offset;
672 uint64_t size = lr->lr_length;
673 dmu_buf_t *db;
674 zgd_t *zgd;
675 int error;
676
677 ASSERT3P(lwb, !=, NULL);
678 ASSERT3U(size, !=, 0);
679
680 zgd = kmem_zalloc(sizeof (zgd_t), KM_SLEEP);
681 zgd->zgd_lwb = lwb;
682
683 /*
684 * Write records come in two flavors: immediate and indirect.
685 * For small writes it's cheaper to store the data with the
686 * log record (immediate); for large writes it's cheaper to
687 * sync the data and get a pointer to it (indirect) so that
688 * we don't have to write the data twice.
689 */
690 if (buf != NULL) { /* immediate write */
691 zgd->zgd_lr = zfs_rangelock_enter(&zv->zv_rangelock, offset,
692 size, RL_READER);
693 error = dmu_read_by_dnode(zv->zv_dn, offset, size, buf,
694 DMU_READ_NO_PREFETCH);
695 } else { /* indirect write */
696 ASSERT3P(zio, !=, NULL);
697 /*
698 * Have to lock the whole block to ensure when it's written out
699 * and its checksum is being calculated that no one can change
700 * the data. Contrarily to zfs_get_data we need not re-check
701 * blocksize after we get the lock because it cannot be changed.
702 */
703 size = zv->zv_volblocksize;
704 offset = P2ALIGN_TYPED(offset, size, uint64_t);
705 zgd->zgd_lr = zfs_rangelock_enter(&zv->zv_rangelock, offset,
706 size, RL_READER);
707 error = dmu_buf_hold_noread_by_dnode(zv->zv_dn, offset, zgd,
708 &db);
709 if (error == 0) {
710 blkptr_t *bp = &lr->lr_blkptr;
711
712 zgd->zgd_db = db;
713 zgd->zgd_bp = bp;
714
715 ASSERT(db != NULL);
716 ASSERT(db->db_offset == offset);
717 ASSERT(db->db_size == size);
718
719 error = dmu_sync(zio, lr->lr_common.lrc_txg,
720 zvol_get_done, zgd);
721
722 if (error == 0)
723 return (0);
724 }
725 }
726
727 zvol_get_done(zgd, error);
728
729 return (SET_ERROR(error));
730 }
731
732 /*
733 * The zvol_state_t's are inserted into zvol_state_list and zvol_htable.
734 */
735
736 void
zvol_insert(zvol_state_t * zv)737 zvol_insert(zvol_state_t *zv)
738 {
739 ASSERT(RW_WRITE_HELD(&zvol_state_lock));
740 list_insert_head(&zvol_state_list, zv);
741 hlist_add_head(&zv->zv_hlink, ZVOL_HT_HEAD(zv->zv_hash));
742 }
743
744 /*
745 * Simply remove the zvol from to list of zvols.
746 */
747 static void
zvol_remove(zvol_state_t * zv)748 zvol_remove(zvol_state_t *zv)
749 {
750 ASSERT(RW_WRITE_HELD(&zvol_state_lock));
751 list_remove(&zvol_state_list, zv);
752 hlist_del(&zv->zv_hlink);
753 }
754
755 /*
756 * Setup zv after we just own the zv->objset
757 */
758 static int
zvol_setup_zv(zvol_state_t * zv)759 zvol_setup_zv(zvol_state_t *zv)
760 {
761 uint64_t volsize;
762 int error;
763 uint64_t ro;
764 objset_t *os = zv->zv_objset;
765
766 ASSERT(MUTEX_HELD(&zv->zv_state_lock));
767 ASSERT(RW_LOCK_HELD(&zv->zv_suspend_lock));
768
769 zv->zv_zilog = NULL;
770 zv->zv_flags &= ~ZVOL_WRITTEN_TO;
771
772 error = dsl_prop_get_integer(zv->zv_name, "readonly", &ro, NULL);
773 if (error)
774 return (SET_ERROR(error));
775
776 error = zap_lookup(os, ZVOL_ZAP_OBJ, "size", 8, 1, &volsize);
777 if (error)
778 return (SET_ERROR(error));
779
780 error = dnode_hold(os, ZVOL_OBJ, zv, &zv->zv_dn);
781 if (error)
782 return (SET_ERROR(error));
783
784 zvol_os_set_capacity(zv, volsize >> 9);
785 zv->zv_volsize = volsize;
786
787 if (ro || dmu_objset_is_snapshot(os) ||
788 !spa_writeable(dmu_objset_spa(os))) {
789 zvol_os_set_disk_ro(zv, 1);
790 zv->zv_flags |= ZVOL_RDONLY;
791 } else {
792 zvol_os_set_disk_ro(zv, 0);
793 zv->zv_flags &= ~ZVOL_RDONLY;
794 }
795 return (0);
796 }
797
798 /*
799 * Shutdown every zv_objset related stuff except zv_objset itself.
800 * The is the reverse of zvol_setup_zv.
801 */
802 static void
zvol_shutdown_zv(zvol_state_t * zv)803 zvol_shutdown_zv(zvol_state_t *zv)
804 {
805 ASSERT(MUTEX_HELD(&zv->zv_state_lock) &&
806 RW_LOCK_HELD(&zv->zv_suspend_lock));
807
808 if (zv->zv_flags & ZVOL_WRITTEN_TO) {
809 ASSERT(zv->zv_zilog != NULL);
810 zil_close(zv->zv_zilog);
811 }
812
813 zv->zv_zilog = NULL;
814
815 dnode_rele(zv->zv_dn, zv);
816 zv->zv_dn = NULL;
817
818 /*
819 * Evict cached data. We must write out any dirty data before
820 * disowning the dataset.
821 */
822 if (zv->zv_flags & ZVOL_WRITTEN_TO)
823 txg_wait_synced(dmu_objset_pool(zv->zv_objset), 0);
824 (void) dmu_objset_evict_dbufs(zv->zv_objset);
825 }
826
827 /*
828 * return the proper tag for rollback and recv
829 */
830 void *
zvol_tag(zvol_state_t * zv)831 zvol_tag(zvol_state_t *zv)
832 {
833 ASSERT(RW_WRITE_HELD(&zv->zv_suspend_lock));
834 return (zv->zv_open_count > 0 ? zv : NULL);
835 }
836
837 /*
838 * Suspend the zvol for recv and rollback.
839 */
840 zvol_state_t *
zvol_suspend(const char * name)841 zvol_suspend(const char *name)
842 {
843 zvol_state_t *zv;
844
845 zv = zvol_find_by_name(name, RW_WRITER);
846
847 if (zv == NULL)
848 return (NULL);
849
850 /* block all I/O, release in zvol_resume. */
851 ASSERT(MUTEX_HELD(&zv->zv_state_lock));
852 ASSERT(RW_WRITE_HELD(&zv->zv_suspend_lock));
853
854 atomic_inc(&zv->zv_suspend_ref);
855
856 if (zv->zv_open_count > 0)
857 zvol_shutdown_zv(zv);
858
859 /*
860 * do not hold zv_state_lock across suspend/resume to
861 * avoid locking up zvol lookups
862 */
863 mutex_exit(&zv->zv_state_lock);
864
865 /* zv_suspend_lock is released in zvol_resume() */
866 return (zv);
867 }
868
869 int
zvol_resume(zvol_state_t * zv)870 zvol_resume(zvol_state_t *zv)
871 {
872 int error = 0;
873
874 ASSERT(RW_WRITE_HELD(&zv->zv_suspend_lock));
875
876 mutex_enter(&zv->zv_state_lock);
877
878 if (zv->zv_open_count > 0) {
879 VERIFY0(dmu_objset_hold(zv->zv_name, zv, &zv->zv_objset));
880 VERIFY3P(zv->zv_objset->os_dsl_dataset->ds_owner, ==, zv);
881 VERIFY(dsl_dataset_long_held(zv->zv_objset->os_dsl_dataset));
882 dmu_objset_rele(zv->zv_objset, zv);
883
884 error = zvol_setup_zv(zv);
885 }
886
887 mutex_exit(&zv->zv_state_lock);
888
889 rw_exit(&zv->zv_suspend_lock);
890 /*
891 * We need this because we don't hold zvol_state_lock while releasing
892 * zv_suspend_lock. zvol_remove_minors_impl thus cannot check
893 * zv_suspend_lock to determine it is safe to free because rwlock is
894 * not inherent atomic.
895 */
896 atomic_dec(&zv->zv_suspend_ref);
897
898 if (zv->zv_flags & ZVOL_REMOVING)
899 cv_broadcast(&zv->zv_removing_cv);
900
901 return (SET_ERROR(error));
902 }
903
904 int
zvol_first_open(zvol_state_t * zv,boolean_t readonly)905 zvol_first_open(zvol_state_t *zv, boolean_t readonly)
906 {
907 objset_t *os;
908 int error;
909
910 ASSERT(RW_READ_HELD(&zv->zv_suspend_lock));
911 ASSERT(MUTEX_HELD(&zv->zv_state_lock));
912 ASSERT(mutex_owned(&spa_namespace_lock));
913
914 boolean_t ro = (readonly || (strchr(zv->zv_name, '@') != NULL));
915 error = dmu_objset_own(zv->zv_name, DMU_OST_ZVOL, ro, B_TRUE, zv, &os);
916 if (error)
917 return (SET_ERROR(error));
918
919 zv->zv_objset = os;
920
921 error = zvol_setup_zv(zv);
922 if (error) {
923 dmu_objset_disown(os, 1, zv);
924 zv->zv_objset = NULL;
925 }
926
927 return (error);
928 }
929
930 void
zvol_last_close(zvol_state_t * zv)931 zvol_last_close(zvol_state_t *zv)
932 {
933 ASSERT(RW_READ_HELD(&zv->zv_suspend_lock));
934 ASSERT(MUTEX_HELD(&zv->zv_state_lock));
935
936 if (zv->zv_flags & ZVOL_REMOVING)
937 cv_broadcast(&zv->zv_removing_cv);
938
939 zvol_shutdown_zv(zv);
940
941 dmu_objset_disown(zv->zv_objset, 1, zv);
942 zv->zv_objset = NULL;
943 }
944
945 typedef struct minors_job {
946 list_t *list;
947 list_node_t link;
948 /* input */
949 char *name;
950 /* output */
951 int error;
952 } minors_job_t;
953
954 /*
955 * Prefetch zvol dnodes for the minors_job
956 */
957 static void
zvol_prefetch_minors_impl(void * arg)958 zvol_prefetch_minors_impl(void *arg)
959 {
960 minors_job_t *job = arg;
961 char *dsname = job->name;
962 objset_t *os = NULL;
963
964 job->error = dmu_objset_own(dsname, DMU_OST_ZVOL, B_TRUE, B_TRUE,
965 FTAG, &os);
966 if (job->error == 0) {
967 dmu_prefetch_dnode(os, ZVOL_OBJ, ZIO_PRIORITY_SYNC_READ);
968 dmu_objset_disown(os, B_TRUE, FTAG);
969 }
970 }
971
972 /*
973 * Mask errors to continue dmu_objset_find() traversal
974 */
975 static int
zvol_create_snap_minor_cb(const char * dsname,void * arg)976 zvol_create_snap_minor_cb(const char *dsname, void *arg)
977 {
978 minors_job_t *j = arg;
979 list_t *minors_list = j->list;
980 const char *name = j->name;
981
982 ASSERT0(MUTEX_HELD(&spa_namespace_lock));
983
984 /* skip the designated dataset */
985 if (name && strcmp(dsname, name) == 0)
986 return (0);
987
988 /* at this point, the dsname should name a snapshot */
989 if (strchr(dsname, '@') == 0) {
990 dprintf("zvol_create_snap_minor_cb(): "
991 "%s is not a snapshot name\n", dsname);
992 } else {
993 minors_job_t *job;
994 char *n = kmem_strdup(dsname);
995 if (n == NULL)
996 return (0);
997
998 job = kmem_alloc(sizeof (minors_job_t), KM_SLEEP);
999 job->name = n;
1000 job->list = minors_list;
1001 job->error = 0;
1002 list_insert_tail(minors_list, job);
1003 /* don't care if dispatch fails, because job->error is 0 */
1004 taskq_dispatch(system_taskq, zvol_prefetch_minors_impl, job,
1005 TQ_SLEEP);
1006 }
1007
1008 return (0);
1009 }
1010
1011 /*
1012 * If spa_keystore_load_wkey() is called for an encrypted zvol,
1013 * we need to look for any clones also using the key. This function
1014 * is "best effort" - so we just skip over it if there are failures.
1015 */
1016 static void
zvol_add_clones(const char * dsname,list_t * minors_list)1017 zvol_add_clones(const char *dsname, list_t *minors_list)
1018 {
1019 /* Also check if it has clones */
1020 dsl_dir_t *dd = NULL;
1021 dsl_pool_t *dp = NULL;
1022
1023 if (dsl_pool_hold(dsname, FTAG, &dp) != 0)
1024 return;
1025
1026 if (!spa_feature_is_enabled(dp->dp_spa,
1027 SPA_FEATURE_ENCRYPTION))
1028 goto out;
1029
1030 if (dsl_dir_hold(dp, dsname, FTAG, &dd, NULL) != 0)
1031 goto out;
1032
1033 if (dsl_dir_phys(dd)->dd_clones == 0)
1034 goto out;
1035
1036 zap_cursor_t *zc = kmem_alloc(sizeof (zap_cursor_t), KM_SLEEP);
1037 zap_attribute_t *za = zap_attribute_alloc();
1038 objset_t *mos = dd->dd_pool->dp_meta_objset;
1039
1040 for (zap_cursor_init(zc, mos, dsl_dir_phys(dd)->dd_clones);
1041 zap_cursor_retrieve(zc, za) == 0;
1042 zap_cursor_advance(zc)) {
1043 dsl_dataset_t *clone;
1044 minors_job_t *job;
1045
1046 if (dsl_dataset_hold_obj(dd->dd_pool,
1047 za->za_first_integer, FTAG, &clone) == 0) {
1048
1049 char name[ZFS_MAX_DATASET_NAME_LEN];
1050 dsl_dataset_name(clone, name);
1051
1052 char *n = kmem_strdup(name);
1053 job = kmem_alloc(sizeof (minors_job_t), KM_SLEEP);
1054 job->name = n;
1055 job->list = minors_list;
1056 job->error = 0;
1057 list_insert_tail(minors_list, job);
1058
1059 dsl_dataset_rele(clone, FTAG);
1060 }
1061 }
1062 zap_cursor_fini(zc);
1063 zap_attribute_free(za);
1064 kmem_free(zc, sizeof (zap_cursor_t));
1065
1066 out:
1067 if (dd != NULL)
1068 dsl_dir_rele(dd, FTAG);
1069 dsl_pool_rele(dp, FTAG);
1070 }
1071
1072 /*
1073 * Mask errors to continue dmu_objset_find() traversal
1074 */
1075 static int
zvol_create_minors_cb(const char * dsname,void * arg)1076 zvol_create_minors_cb(const char *dsname, void *arg)
1077 {
1078 uint64_t snapdev;
1079 int error;
1080 list_t *minors_list = arg;
1081
1082 ASSERT0(MUTEX_HELD(&spa_namespace_lock));
1083
1084 error = dsl_prop_get_integer(dsname, "snapdev", &snapdev, NULL);
1085 if (error)
1086 return (0);
1087
1088 /*
1089 * Given the name and the 'snapdev' property, create device minor nodes
1090 * with the linkages to zvols/snapshots as needed.
1091 * If the name represents a zvol, create a minor node for the zvol, then
1092 * check if its snapshots are 'visible', and if so, iterate over the
1093 * snapshots and create device minor nodes for those.
1094 */
1095 if (strchr(dsname, '@') == 0) {
1096 minors_job_t *job;
1097 char *n = kmem_strdup(dsname);
1098 if (n == NULL)
1099 return (0);
1100
1101 job = kmem_alloc(sizeof (minors_job_t), KM_SLEEP);
1102 job->name = n;
1103 job->list = minors_list;
1104 job->error = 0;
1105 list_insert_tail(minors_list, job);
1106 /* don't care if dispatch fails, because job->error is 0 */
1107 taskq_dispatch(system_taskq, zvol_prefetch_minors_impl, job,
1108 TQ_SLEEP);
1109
1110 zvol_add_clones(dsname, minors_list);
1111
1112 if (snapdev == ZFS_SNAPDEV_VISIBLE) {
1113 /*
1114 * traverse snapshots only, do not traverse children,
1115 * and skip the 'dsname'
1116 */
1117 (void) dmu_objset_find(dsname,
1118 zvol_create_snap_minor_cb, (void *)job,
1119 DS_FIND_SNAPSHOTS);
1120 }
1121 } else {
1122 dprintf("zvol_create_minors_cb(): %s is not a zvol name\n",
1123 dsname);
1124 }
1125
1126 return (0);
1127 }
1128
1129 /*
1130 * Create minors for the specified dataset, including children and snapshots.
1131 * Pay attention to the 'snapdev' property and iterate over the snapshots
1132 * only if they are 'visible'. This approach allows one to assure that the
1133 * snapshot metadata is read from disk only if it is needed.
1134 *
1135 * The name can represent a dataset to be recursively scanned for zvols and
1136 * their snapshots, or a single zvol snapshot. If the name represents a
1137 * dataset, the scan is performed in two nested stages:
1138 * - scan the dataset for zvols, and
1139 * - for each zvol, create a minor node, then check if the zvol's snapshots
1140 * are 'visible', and only then iterate over the snapshots if needed
1141 *
1142 * If the name represents a snapshot, a check is performed if the snapshot is
1143 * 'visible' (which also verifies that the parent is a zvol), and if so,
1144 * a minor node for that snapshot is created.
1145 */
1146 void
zvol_create_minors_recursive(const char * name)1147 zvol_create_minors_recursive(const char *name)
1148 {
1149 list_t minors_list;
1150 minors_job_t *job;
1151
1152 if (zvol_inhibit_dev)
1153 return;
1154
1155 /*
1156 * This is the list for prefetch jobs. Whenever we found a match
1157 * during dmu_objset_find, we insert a minors_job to the list and do
1158 * taskq_dispatch to parallel prefetch zvol dnodes. Note we don't need
1159 * any lock because all list operation is done on the current thread.
1160 *
1161 * We will use this list to do zvol_os_create_minor after prefetch
1162 * so we don't have to traverse using dmu_objset_find again.
1163 */
1164 list_create(&minors_list, sizeof (minors_job_t),
1165 offsetof(minors_job_t, link));
1166
1167
1168 if (strchr(name, '@') != NULL) {
1169 uint64_t snapdev;
1170
1171 int error = dsl_prop_get_integer(name, "snapdev",
1172 &snapdev, NULL);
1173
1174 if (error == 0 && snapdev == ZFS_SNAPDEV_VISIBLE)
1175 (void) zvol_os_create_minor(name);
1176 } else {
1177 fstrans_cookie_t cookie = spl_fstrans_mark();
1178 (void) dmu_objset_find(name, zvol_create_minors_cb,
1179 &minors_list, DS_FIND_CHILDREN);
1180 spl_fstrans_unmark(cookie);
1181 }
1182
1183 taskq_wait_outstanding(system_taskq, 0);
1184
1185 /*
1186 * Prefetch is completed, we can do zvol_os_create_minor
1187 * sequentially.
1188 */
1189 while ((job = list_remove_head(&minors_list)) != NULL) {
1190 if (!job->error)
1191 (void) zvol_os_create_minor(job->name);
1192 kmem_strfree(job->name);
1193 kmem_free(job, sizeof (minors_job_t));
1194 }
1195
1196 list_destroy(&minors_list);
1197 }
1198
1199 void
zvol_create_minor(const char * name)1200 zvol_create_minor(const char *name)
1201 {
1202 /*
1203 * Note: the dsl_pool_config_lock must not be held.
1204 * Minor node creation needs to obtain the zvol_state_lock.
1205 * zvol_open() obtains the zvol_state_lock and then the dsl pool
1206 * config lock. Therefore, we can't have the config lock now if
1207 * we are going to wait for the zvol_state_lock, because it
1208 * would be a lock order inversion which could lead to deadlock.
1209 */
1210
1211 if (zvol_inhibit_dev)
1212 return;
1213
1214 if (strchr(name, '@') != NULL) {
1215 uint64_t snapdev;
1216
1217 int error = dsl_prop_get_integer(name,
1218 "snapdev", &snapdev, NULL);
1219
1220 if (error == 0 && snapdev == ZFS_SNAPDEV_VISIBLE)
1221 (void) zvol_os_create_minor(name);
1222 } else {
1223 (void) zvol_os_create_minor(name);
1224 }
1225 }
1226
1227 /*
1228 * Remove minors for specified dataset including children and snapshots.
1229 */
1230
1231 /*
1232 * Remove the minor for a given zvol. This will do it all:
1233 * - flag the zvol for removal, so new requests are rejected
1234 * - wait until outstanding requests are completed
1235 * - remove it from lists
1236 * - free it
1237 * It's also usable as a taskq task, and smells nice too.
1238 */
1239 static void
zvol_remove_minor_task(void * arg)1240 zvol_remove_minor_task(void *arg)
1241 {
1242 zvol_state_t *zv = (zvol_state_t *)arg;
1243
1244 ASSERT(!RW_LOCK_HELD(&zvol_state_lock));
1245 ASSERT(!MUTEX_HELD(&zv->zv_state_lock));
1246
1247 mutex_enter(&zv->zv_state_lock);
1248 while (zv->zv_open_count > 0 || atomic_read(&zv->zv_suspend_ref)) {
1249 zv->zv_flags |= ZVOL_REMOVING;
1250 cv_wait(&zv->zv_removing_cv, &zv->zv_state_lock);
1251 }
1252 mutex_exit(&zv->zv_state_lock);
1253
1254 rw_enter(&zvol_state_lock, RW_WRITER);
1255 mutex_enter(&zv->zv_state_lock);
1256
1257 zvol_remove(zv);
1258 zvol_os_clear_private(zv);
1259
1260 mutex_exit(&zv->zv_state_lock);
1261 rw_exit(&zvol_state_lock);
1262
1263 zvol_os_free(zv);
1264 }
1265
1266 static void
zvol_free_task(void * arg)1267 zvol_free_task(void *arg)
1268 {
1269 zvol_os_free(arg);
1270 }
1271
1272 void
zvol_remove_minors_impl(const char * name)1273 zvol_remove_minors_impl(const char *name)
1274 {
1275 zvol_state_t *zv, *zv_next;
1276 int namelen = ((name) ? strlen(name) : 0);
1277 taskqid_t t;
1278 list_t delay_list, free_list;
1279
1280 if (zvol_inhibit_dev)
1281 return;
1282
1283 list_create(&delay_list, sizeof (zvol_state_t),
1284 offsetof(zvol_state_t, zv_next));
1285 list_create(&free_list, sizeof (zvol_state_t),
1286 offsetof(zvol_state_t, zv_next));
1287
1288 rw_enter(&zvol_state_lock, RW_WRITER);
1289
1290 for (zv = list_head(&zvol_state_list); zv != NULL; zv = zv_next) {
1291 zv_next = list_next(&zvol_state_list, zv);
1292
1293 mutex_enter(&zv->zv_state_lock);
1294 if (name == NULL || strcmp(zv->zv_name, name) == 0 ||
1295 (strncmp(zv->zv_name, name, namelen) == 0 &&
1296 (zv->zv_name[namelen] == '/' ||
1297 zv->zv_name[namelen] == '@'))) {
1298 /*
1299 * By holding zv_state_lock here, we guarantee that no
1300 * one is currently using this zv
1301 */
1302
1303 /*
1304 * If in use, try to throw everyone off and try again
1305 * later.
1306 */
1307 if (zv->zv_open_count > 0 ||
1308 atomic_read(&zv->zv_suspend_ref)) {
1309 zv->zv_flags |= ZVOL_REMOVING;
1310 t = taskq_dispatch(
1311 zv->zv_objset->os_spa->spa_zvol_taskq,
1312 zvol_remove_minor_task, zv, TQ_SLEEP);
1313 if (t == TASKQID_INVALID) {
1314 /*
1315 * Couldn't create the task, so we'll
1316 * do it in place once the loop is
1317 * finished.
1318 */
1319 list_insert_head(&delay_list, zv);
1320 }
1321 mutex_exit(&zv->zv_state_lock);
1322 continue;
1323 }
1324
1325 zvol_remove(zv);
1326
1327 /*
1328 * Cleared while holding zvol_state_lock as a writer
1329 * which will prevent zvol_open() from opening it.
1330 */
1331 zvol_os_clear_private(zv);
1332
1333 /* Drop zv_state_lock before zvol_free() */
1334 mutex_exit(&zv->zv_state_lock);
1335
1336 /* Try parallel zv_free, if failed do it in place */
1337 t = taskq_dispatch(system_taskq, zvol_free_task, zv,
1338 TQ_SLEEP);
1339 if (t == TASKQID_INVALID)
1340 list_insert_head(&free_list, zv);
1341 } else {
1342 mutex_exit(&zv->zv_state_lock);
1343 }
1344 }
1345 rw_exit(&zvol_state_lock);
1346
1347 /* Wait for zvols that we couldn't create a remove task for */
1348 while ((zv = list_remove_head(&delay_list)) != NULL)
1349 zvol_remove_minor_task(zv);
1350
1351 /* Free any that we couldn't free in parallel earlier */
1352 while ((zv = list_remove_head(&free_list)) != NULL)
1353 zvol_os_free(zv);
1354 }
1355
1356 /* Remove minor for this specific volume only */
1357 static void
zvol_remove_minor_impl(const char * name)1358 zvol_remove_minor_impl(const char *name)
1359 {
1360 zvol_state_t *zv = NULL, *zv_next;
1361
1362 if (zvol_inhibit_dev)
1363 return;
1364
1365 rw_enter(&zvol_state_lock, RW_WRITER);
1366
1367 for (zv = list_head(&zvol_state_list); zv != NULL; zv = zv_next) {
1368 zv_next = list_next(&zvol_state_list, zv);
1369
1370 mutex_enter(&zv->zv_state_lock);
1371 if (strcmp(zv->zv_name, name) == 0)
1372 /* Found, leave the the loop with zv_lock held */
1373 break;
1374 mutex_exit(&zv->zv_state_lock);
1375 }
1376
1377 if (zv == NULL) {
1378 rw_exit(&zvol_state_lock);
1379 return;
1380 }
1381
1382 ASSERT(MUTEX_HELD(&zv->zv_state_lock));
1383
1384 if (zv->zv_open_count > 0 || atomic_read(&zv->zv_suspend_ref)) {
1385 /*
1386 * In use, so try to throw everyone off, then wait
1387 * until finished.
1388 */
1389 zv->zv_flags |= ZVOL_REMOVING;
1390 mutex_exit(&zv->zv_state_lock);
1391 rw_exit(&zvol_state_lock);
1392 zvol_remove_minor_task(zv);
1393 return;
1394 }
1395
1396 zvol_remove(zv);
1397 zvol_os_clear_private(zv);
1398
1399 mutex_exit(&zv->zv_state_lock);
1400 rw_exit(&zvol_state_lock);
1401
1402 zvol_os_free(zv);
1403 }
1404
1405 /*
1406 * Rename minors for specified dataset including children and snapshots.
1407 */
1408 static void
zvol_rename_minors_impl(const char * oldname,const char * newname)1409 zvol_rename_minors_impl(const char *oldname, const char *newname)
1410 {
1411 zvol_state_t *zv, *zv_next;
1412 int oldnamelen;
1413
1414 if (zvol_inhibit_dev)
1415 return;
1416
1417 oldnamelen = strlen(oldname);
1418
1419 rw_enter(&zvol_state_lock, RW_READER);
1420
1421 for (zv = list_head(&zvol_state_list); zv != NULL; zv = zv_next) {
1422 zv_next = list_next(&zvol_state_list, zv);
1423
1424 mutex_enter(&zv->zv_state_lock);
1425
1426 if (strcmp(zv->zv_name, oldname) == 0) {
1427 zvol_os_rename_minor(zv, newname);
1428 } else if (strncmp(zv->zv_name, oldname, oldnamelen) == 0 &&
1429 (zv->zv_name[oldnamelen] == '/' ||
1430 zv->zv_name[oldnamelen] == '@')) {
1431 char *name = kmem_asprintf("%s%c%s", newname,
1432 zv->zv_name[oldnamelen],
1433 zv->zv_name + oldnamelen + 1);
1434 zvol_os_rename_minor(zv, name);
1435 kmem_strfree(name);
1436 }
1437
1438 mutex_exit(&zv->zv_state_lock);
1439 }
1440
1441 rw_exit(&zvol_state_lock);
1442 }
1443
1444 typedef struct zvol_snapdev_cb_arg {
1445 uint64_t snapdev;
1446 } zvol_snapdev_cb_arg_t;
1447
1448 static int
zvol_set_snapdev_cb(const char * dsname,void * param)1449 zvol_set_snapdev_cb(const char *dsname, void *param)
1450 {
1451 zvol_snapdev_cb_arg_t *arg = param;
1452
1453 if (strchr(dsname, '@') == NULL)
1454 return (0);
1455
1456 switch (arg->snapdev) {
1457 case ZFS_SNAPDEV_VISIBLE:
1458 (void) zvol_os_create_minor(dsname);
1459 break;
1460 case ZFS_SNAPDEV_HIDDEN:
1461 (void) zvol_remove_minor_impl(dsname);
1462 break;
1463 }
1464
1465 return (0);
1466 }
1467
1468 static void
zvol_set_snapdev_impl(char * name,uint64_t snapdev)1469 zvol_set_snapdev_impl(char *name, uint64_t snapdev)
1470 {
1471 zvol_snapdev_cb_arg_t arg = {snapdev};
1472 fstrans_cookie_t cookie = spl_fstrans_mark();
1473 /*
1474 * The zvol_set_snapdev_sync() sets snapdev appropriately
1475 * in the dataset hierarchy. Here, we only scan snapshots.
1476 */
1477 dmu_objset_find(name, zvol_set_snapdev_cb, &arg, DS_FIND_SNAPSHOTS);
1478 spl_fstrans_unmark(cookie);
1479 }
1480
1481 static void
zvol_set_volmode_impl(char * name,uint64_t volmode)1482 zvol_set_volmode_impl(char *name, uint64_t volmode)
1483 {
1484 fstrans_cookie_t cookie;
1485 uint64_t old_volmode;
1486 zvol_state_t *zv;
1487
1488 if (strchr(name, '@') != NULL)
1489 return;
1490
1491 /*
1492 * It's unfortunate we need to remove minors before we create new ones:
1493 * this is necessary because our backing gendisk (zvol_state->zv_disk)
1494 * could be different when we set, for instance, volmode from "geom"
1495 * to "dev" (or vice versa).
1496 */
1497 zv = zvol_find_by_name(name, RW_NONE);
1498 if (zv == NULL && volmode == ZFS_VOLMODE_NONE)
1499 return;
1500 if (zv != NULL) {
1501 old_volmode = zv->zv_volmode;
1502 mutex_exit(&zv->zv_state_lock);
1503 if (old_volmode == volmode)
1504 return;
1505 zvol_wait_close(zv);
1506 }
1507 cookie = spl_fstrans_mark();
1508 switch (volmode) {
1509 case ZFS_VOLMODE_NONE:
1510 (void) zvol_remove_minor_impl(name);
1511 break;
1512 case ZFS_VOLMODE_GEOM:
1513 case ZFS_VOLMODE_DEV:
1514 (void) zvol_remove_minor_impl(name);
1515 (void) zvol_os_create_minor(name);
1516 break;
1517 case ZFS_VOLMODE_DEFAULT:
1518 (void) zvol_remove_minor_impl(name);
1519 if (zvol_volmode == ZFS_VOLMODE_NONE)
1520 break;
1521 else /* if zvol_volmode is invalid defaults to "geom" */
1522 (void) zvol_os_create_minor(name);
1523 break;
1524 }
1525 spl_fstrans_unmark(cookie);
1526 }
1527
1528 static zvol_task_t *
zvol_task_alloc(zvol_async_op_t op,const char * name1,const char * name2,uint64_t value)1529 zvol_task_alloc(zvol_async_op_t op, const char *name1, const char *name2,
1530 uint64_t value)
1531 {
1532 zvol_task_t *task;
1533
1534 /* Never allow tasks on hidden names. */
1535 if (name1[0] == '$')
1536 return (NULL);
1537
1538 task = kmem_zalloc(sizeof (zvol_task_t), KM_SLEEP);
1539 task->op = op;
1540 task->value = value;
1541
1542 strlcpy(task->name1, name1, sizeof (task->name1));
1543 if (name2 != NULL)
1544 strlcpy(task->name2, name2, sizeof (task->name2));
1545
1546 return (task);
1547 }
1548
1549 static void
zvol_task_free(zvol_task_t * task)1550 zvol_task_free(zvol_task_t *task)
1551 {
1552 kmem_free(task, sizeof (zvol_task_t));
1553 }
1554
1555 /*
1556 * The worker thread function performed asynchronously.
1557 */
1558 static void
zvol_task_cb(void * arg)1559 zvol_task_cb(void *arg)
1560 {
1561 zvol_task_t *task = arg;
1562
1563 switch (task->op) {
1564 case ZVOL_ASYNC_REMOVE_MINORS:
1565 zvol_remove_minors_impl(task->name1);
1566 break;
1567 case ZVOL_ASYNC_RENAME_MINORS:
1568 zvol_rename_minors_impl(task->name1, task->name2);
1569 break;
1570 case ZVOL_ASYNC_SET_SNAPDEV:
1571 zvol_set_snapdev_impl(task->name1, task->value);
1572 break;
1573 case ZVOL_ASYNC_SET_VOLMODE:
1574 zvol_set_volmode_impl(task->name1, task->value);
1575 break;
1576 default:
1577 VERIFY(0);
1578 break;
1579 }
1580
1581 zvol_task_free(task);
1582 }
1583
1584 typedef struct zvol_set_prop_int_arg {
1585 const char *zsda_name;
1586 uint64_t zsda_value;
1587 zprop_source_t zsda_source;
1588 zfs_prop_t zsda_prop;
1589 } zvol_set_prop_int_arg_t;
1590
1591 /*
1592 * Sanity check the dataset for safe use by the sync task. No additional
1593 * conditions are imposed.
1594 */
1595 static int
zvol_set_common_check(void * arg,dmu_tx_t * tx)1596 zvol_set_common_check(void *arg, dmu_tx_t *tx)
1597 {
1598 zvol_set_prop_int_arg_t *zsda = arg;
1599 dsl_pool_t *dp = dmu_tx_pool(tx);
1600 dsl_dir_t *dd;
1601 int error;
1602
1603 error = dsl_dir_hold(dp, zsda->zsda_name, FTAG, &dd, NULL);
1604 if (error != 0)
1605 return (error);
1606
1607 dsl_dir_rele(dd, FTAG);
1608
1609 return (error);
1610 }
1611
1612 static int
zvol_set_common_sync_cb(dsl_pool_t * dp,dsl_dataset_t * ds,void * arg)1613 zvol_set_common_sync_cb(dsl_pool_t *dp, dsl_dataset_t *ds, void *arg)
1614 {
1615 zvol_set_prop_int_arg_t *zsda = arg;
1616 char dsname[ZFS_MAX_DATASET_NAME_LEN];
1617 zvol_task_t *task;
1618 uint64_t prop;
1619
1620 const char *prop_name = zfs_prop_to_name(zsda->zsda_prop);
1621 dsl_dataset_name(ds, dsname);
1622
1623 if (dsl_prop_get_int_ds(ds, prop_name, &prop) != 0)
1624 return (0);
1625
1626 switch (zsda->zsda_prop) {
1627 case ZFS_PROP_VOLMODE:
1628 task = zvol_task_alloc(ZVOL_ASYNC_SET_VOLMODE, dsname,
1629 NULL, prop);
1630 break;
1631 case ZFS_PROP_SNAPDEV:
1632 task = zvol_task_alloc(ZVOL_ASYNC_SET_SNAPDEV, dsname,
1633 NULL, prop);
1634 break;
1635 default:
1636 task = NULL;
1637 break;
1638 }
1639
1640 if (task == NULL)
1641 return (0);
1642
1643 (void) taskq_dispatch(dp->dp_spa->spa_zvol_taskq, zvol_task_cb,
1644 task, TQ_SLEEP);
1645 return (0);
1646 }
1647
1648 /*
1649 * Traverse all child datasets and apply the property appropriately.
1650 * We call dsl_prop_set_sync_impl() here to set the value only on the toplevel
1651 * dataset and read the effective "property" on every child in the callback
1652 * function: this is because the value is not guaranteed to be the same in the
1653 * whole dataset hierarchy.
1654 */
1655 static void
zvol_set_common_sync(void * arg,dmu_tx_t * tx)1656 zvol_set_common_sync(void *arg, dmu_tx_t *tx)
1657 {
1658 zvol_set_prop_int_arg_t *zsda = arg;
1659 dsl_pool_t *dp = dmu_tx_pool(tx);
1660 dsl_dir_t *dd;
1661 dsl_dataset_t *ds;
1662 int error;
1663
1664 VERIFY0(dsl_dir_hold(dp, zsda->zsda_name, FTAG, &dd, NULL));
1665
1666 error = dsl_dataset_hold(dp, zsda->zsda_name, FTAG, &ds);
1667 if (error == 0) {
1668 dsl_prop_set_sync_impl(ds, zfs_prop_to_name(zsda->zsda_prop),
1669 zsda->zsda_source, sizeof (zsda->zsda_value), 1,
1670 &zsda->zsda_value, tx);
1671 dsl_dataset_rele(ds, FTAG);
1672 }
1673
1674 dmu_objset_find_dp(dp, dd->dd_object, zvol_set_common_sync_cb,
1675 zsda, DS_FIND_CHILDREN);
1676
1677 dsl_dir_rele(dd, FTAG);
1678 }
1679
1680 int
zvol_set_common(const char * ddname,zfs_prop_t prop,zprop_source_t source,uint64_t val)1681 zvol_set_common(const char *ddname, zfs_prop_t prop, zprop_source_t source,
1682 uint64_t val)
1683 {
1684 zvol_set_prop_int_arg_t zsda;
1685
1686 zsda.zsda_name = ddname;
1687 zsda.zsda_source = source;
1688 zsda.zsda_value = val;
1689 zsda.zsda_prop = prop;
1690
1691 return (dsl_sync_task(ddname, zvol_set_common_check,
1692 zvol_set_common_sync, &zsda, 0, ZFS_SPACE_CHECK_NONE));
1693 }
1694
1695 void
zvol_remove_minors(spa_t * spa,const char * name,boolean_t async)1696 zvol_remove_minors(spa_t *spa, const char *name, boolean_t async)
1697 {
1698 zvol_task_t *task;
1699 taskqid_t id;
1700
1701 task = zvol_task_alloc(ZVOL_ASYNC_REMOVE_MINORS, name, NULL, ~0ULL);
1702 if (task == NULL)
1703 return;
1704
1705 id = taskq_dispatch(spa->spa_zvol_taskq, zvol_task_cb, task, TQ_SLEEP);
1706 if ((async == B_FALSE) && (id != TASKQID_INVALID))
1707 taskq_wait_id(spa->spa_zvol_taskq, id);
1708 }
1709
1710 void
zvol_rename_minors(spa_t * spa,const char * name1,const char * name2,boolean_t async)1711 zvol_rename_minors(spa_t *spa, const char *name1, const char *name2,
1712 boolean_t async)
1713 {
1714 zvol_task_t *task;
1715 taskqid_t id;
1716
1717 task = zvol_task_alloc(ZVOL_ASYNC_RENAME_MINORS, name1, name2, ~0ULL);
1718 if (task == NULL)
1719 return;
1720
1721 id = taskq_dispatch(spa->spa_zvol_taskq, zvol_task_cb, task, TQ_SLEEP);
1722 if ((async == B_FALSE) && (id != TASKQID_INVALID))
1723 taskq_wait_id(spa->spa_zvol_taskq, id);
1724 }
1725
1726 boolean_t
zvol_is_zvol(const char * name)1727 zvol_is_zvol(const char *name)
1728 {
1729
1730 return (zvol_os_is_zvol(name));
1731 }
1732
1733 int
zvol_init_impl(void)1734 zvol_init_impl(void)
1735 {
1736 int i;
1737
1738 list_create(&zvol_state_list, sizeof (zvol_state_t),
1739 offsetof(zvol_state_t, zv_next));
1740 rw_init(&zvol_state_lock, NULL, RW_DEFAULT, NULL);
1741
1742 zvol_htable = kmem_alloc(ZVOL_HT_SIZE * sizeof (struct hlist_head),
1743 KM_SLEEP);
1744 for (i = 0; i < ZVOL_HT_SIZE; i++)
1745 INIT_HLIST_HEAD(&zvol_htable[i]);
1746
1747 return (0);
1748 }
1749
1750 void
zvol_fini_impl(void)1751 zvol_fini_impl(void)
1752 {
1753 zvol_remove_minors_impl(NULL);
1754
1755 /*
1756 * The call to "zvol_remove_minors_impl" may dispatch entries to
1757 * the system_taskq, but it doesn't wait for those entries to
1758 * complete before it returns. Thus, we must wait for all of the
1759 * removals to finish, before we can continue.
1760 */
1761 taskq_wait_outstanding(system_taskq, 0);
1762
1763 kmem_free(zvol_htable, ZVOL_HT_SIZE * sizeof (struct hlist_head));
1764 list_destroy(&zvol_state_list);
1765 rw_destroy(&zvol_state_lock);
1766 }
1767