xref: /linux/fs/bcachefs/super.c (revision 9c2f5b6eb8b7da05e13cde60c32e0a8b1f5873b0)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * bcachefs setup/teardown code, and some metadata io - read a superblock and
4  * figure out what to do with it.
5  *
6  * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
7  * Copyright 2012 Google, Inc.
8  */
9 
10 #include "bcachefs.h"
11 #include "alloc_background.h"
12 #include "alloc_foreground.h"
13 #include "bkey_sort.h"
14 #include "btree_cache.h"
15 #include "btree_gc.h"
16 #include "btree_journal_iter.h"
17 #include "btree_key_cache.h"
18 #include "btree_node_scan.h"
19 #include "btree_update_interior.h"
20 #include "btree_io.h"
21 #include "btree_write_buffer.h"
22 #include "buckets_waiting_for_journal.h"
23 #include "chardev.h"
24 #include "checksum.h"
25 #include "clock.h"
26 #include "compress.h"
27 #include "debug.h"
28 #include "disk_groups.h"
29 #include "ec.h"
30 #include "errcode.h"
31 #include "error.h"
32 #include "fs.h"
33 #include "fs-io.h"
34 #include "fs-io-buffered.h"
35 #include "fs-io-direct.h"
36 #include "fsck.h"
37 #include "inode.h"
38 #include "io_read.h"
39 #include "io_write.h"
40 #include "journal.h"
41 #include "journal_reclaim.h"
42 #include "journal_seq_blacklist.h"
43 #include "move.h"
44 #include "migrate.h"
45 #include "movinggc.h"
46 #include "nocow_locking.h"
47 #include "quota.h"
48 #include "rebalance.h"
49 #include "recovery.h"
50 #include "replicas.h"
51 #include "sb-clean.h"
52 #include "sb-counters.h"
53 #include "sb-errors.h"
54 #include "sb-members.h"
55 #include "snapshot.h"
56 #include "subvolume.h"
57 #include "super.h"
58 #include "super-io.h"
59 #include "sysfs.h"
60 #include "thread_with_file.h"
61 #include "trace.h"
62 
63 #include <linux/backing-dev.h>
64 #include <linux/blkdev.h>
65 #include <linux/debugfs.h>
66 #include <linux/device.h>
67 #include <linux/idr.h>
68 #include <linux/module.h>
69 #include <linux/percpu.h>
70 #include <linux/random.h>
71 #include <linux/sysfs.h>
72 #include <crypto/hash.h>
73 
74 MODULE_LICENSE("GPL");
75 MODULE_AUTHOR("Kent Overstreet <kent.overstreet@gmail.com>");
76 MODULE_DESCRIPTION("bcachefs filesystem");
77 MODULE_SOFTDEP("pre: crc32c");
78 MODULE_SOFTDEP("pre: crc64");
79 MODULE_SOFTDEP("pre: sha256");
80 MODULE_SOFTDEP("pre: chacha20");
81 MODULE_SOFTDEP("pre: poly1305");
82 MODULE_SOFTDEP("pre: xxhash");
83 
84 const char * const bch2_fs_flag_strs[] = {
85 #define x(n)		#n,
86 	BCH_FS_FLAGS()
87 #undef x
88 	NULL
89 };
90 
91 __printf(2, 0)
92 static void bch2_print_maybe_redirect(struct stdio_redirect *stdio, const char *fmt, va_list args)
93 {
94 #ifdef __KERNEL__
95 	if (unlikely(stdio)) {
96 		if (fmt[0] == KERN_SOH[0])
97 			fmt += 2;
98 
99 		bch2_stdio_redirect_vprintf(stdio, true, fmt, args);
100 		return;
101 	}
102 #endif
103 	vprintk(fmt, args);
104 }
105 
106 void bch2_print_opts(struct bch_opts *opts, const char *fmt, ...)
107 {
108 	struct stdio_redirect *stdio = (void *)(unsigned long)opts->stdio;
109 
110 	va_list args;
111 	va_start(args, fmt);
112 	bch2_print_maybe_redirect(stdio, fmt, args);
113 	va_end(args);
114 }
115 
116 void __bch2_print(struct bch_fs *c, const char *fmt, ...)
117 {
118 	struct stdio_redirect *stdio = bch2_fs_stdio_redirect(c);
119 
120 	va_list args;
121 	va_start(args, fmt);
122 	bch2_print_maybe_redirect(stdio, fmt, args);
123 	va_end(args);
124 }
125 
126 #define KTYPE(type)							\
127 static const struct attribute_group type ## _group = {			\
128 	.attrs = type ## _files						\
129 };									\
130 									\
131 static const struct attribute_group *type ## _groups[] = {		\
132 	&type ## _group,						\
133 	NULL								\
134 };									\
135 									\
136 static const struct kobj_type type ## _ktype = {			\
137 	.release	= type ## _release,				\
138 	.sysfs_ops	= &type ## _sysfs_ops,				\
139 	.default_groups = type ## _groups				\
140 }
141 
142 static void bch2_fs_release(struct kobject *);
143 static void bch2_dev_release(struct kobject *);
144 static void bch2_fs_counters_release(struct kobject *k)
145 {
146 }
147 
148 static void bch2_fs_internal_release(struct kobject *k)
149 {
150 }
151 
152 static void bch2_fs_opts_dir_release(struct kobject *k)
153 {
154 }
155 
156 static void bch2_fs_time_stats_release(struct kobject *k)
157 {
158 }
159 
160 KTYPE(bch2_fs);
161 KTYPE(bch2_fs_counters);
162 KTYPE(bch2_fs_internal);
163 KTYPE(bch2_fs_opts_dir);
164 KTYPE(bch2_fs_time_stats);
165 KTYPE(bch2_dev);
166 
167 static struct kset *bcachefs_kset;
168 static LIST_HEAD(bch_fs_list);
169 static DEFINE_MUTEX(bch_fs_list_lock);
170 
171 DECLARE_WAIT_QUEUE_HEAD(bch2_read_only_wait);
172 
173 static void bch2_dev_free(struct bch_dev *);
174 static int bch2_dev_alloc(struct bch_fs *, unsigned);
175 static int bch2_dev_sysfs_online(struct bch_fs *, struct bch_dev *);
176 static void __bch2_dev_read_only(struct bch_fs *, struct bch_dev *);
177 
178 struct bch_fs *bch2_dev_to_fs(dev_t dev)
179 {
180 	struct bch_fs *c;
181 
182 	mutex_lock(&bch_fs_list_lock);
183 	rcu_read_lock();
184 
185 	list_for_each_entry(c, &bch_fs_list, list)
186 		for_each_member_device_rcu(c, ca, NULL)
187 			if (ca->disk_sb.bdev && ca->disk_sb.bdev->bd_dev == dev) {
188 				closure_get(&c->cl);
189 				goto found;
190 			}
191 	c = NULL;
192 found:
193 	rcu_read_unlock();
194 	mutex_unlock(&bch_fs_list_lock);
195 
196 	return c;
197 }
198 
199 static struct bch_fs *__bch2_uuid_to_fs(__uuid_t uuid)
200 {
201 	struct bch_fs *c;
202 
203 	lockdep_assert_held(&bch_fs_list_lock);
204 
205 	list_for_each_entry(c, &bch_fs_list, list)
206 		if (!memcmp(&c->disk_sb.sb->uuid, &uuid, sizeof(uuid)))
207 			return c;
208 
209 	return NULL;
210 }
211 
212 struct bch_fs *bch2_uuid_to_fs(__uuid_t uuid)
213 {
214 	struct bch_fs *c;
215 
216 	mutex_lock(&bch_fs_list_lock);
217 	c = __bch2_uuid_to_fs(uuid);
218 	if (c)
219 		closure_get(&c->cl);
220 	mutex_unlock(&bch_fs_list_lock);
221 
222 	return c;
223 }
224 
225 static void bch2_dev_usage_journal_reserve(struct bch_fs *c)
226 {
227 	unsigned nr = 0, u64s =
228 		((sizeof(struct jset_entry_dev_usage) +
229 		  sizeof(struct jset_entry_dev_usage_type) * BCH_DATA_NR)) /
230 		sizeof(u64);
231 
232 	rcu_read_lock();
233 	for_each_member_device_rcu(c, ca, NULL)
234 		nr++;
235 	rcu_read_unlock();
236 
237 	bch2_journal_entry_res_resize(&c->journal,
238 			&c->dev_usage_journal_res, u64s * nr);
239 }
240 
241 /* Filesystem RO/RW: */
242 
243 /*
244  * For startup/shutdown of RW stuff, the dependencies are:
245  *
246  * - foreground writes depend on copygc and rebalance (to free up space)
247  *
248  * - copygc and rebalance depend on mark and sweep gc (they actually probably
249  *   don't because they either reserve ahead of time or don't block if
250  *   allocations fail, but allocations can require mark and sweep gc to run
251  *   because of generation number wraparound)
252  *
253  * - all of the above depends on the allocator threads
254  *
255  * - allocator depends on the journal (when it rewrites prios and gens)
256  */
257 
258 static void __bch2_fs_read_only(struct bch_fs *c)
259 {
260 	unsigned clean_passes = 0;
261 	u64 seq = 0;
262 
263 	bch2_fs_ec_stop(c);
264 	bch2_open_buckets_stop(c, NULL, true);
265 	bch2_rebalance_stop(c);
266 	bch2_copygc_stop(c);
267 	bch2_gc_thread_stop(c);
268 	bch2_fs_ec_flush(c);
269 
270 	bch_verbose(c, "flushing journal and stopping allocators, journal seq %llu",
271 		    journal_cur_seq(&c->journal));
272 
273 	do {
274 		clean_passes++;
275 
276 		if (bch2_btree_interior_updates_flush(c) ||
277 		    bch2_journal_flush_all_pins(&c->journal) ||
278 		    bch2_btree_flush_all_writes(c) ||
279 		    seq != atomic64_read(&c->journal.seq)) {
280 			seq = atomic64_read(&c->journal.seq);
281 			clean_passes = 0;
282 		}
283 	} while (clean_passes < 2);
284 
285 	bch_verbose(c, "flushing journal and stopping allocators complete, journal seq %llu",
286 		    journal_cur_seq(&c->journal));
287 
288 	if (test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags) &&
289 	    !test_bit(BCH_FS_emergency_ro, &c->flags))
290 		set_bit(BCH_FS_clean_shutdown, &c->flags);
291 
292 	bch2_fs_journal_stop(&c->journal);
293 
294 	bch_info(c, "%sshutdown complete, journal seq %llu",
295 		 test_bit(BCH_FS_clean_shutdown, &c->flags) ? "" : "un",
296 		 c->journal.seq_ondisk);
297 
298 	/*
299 	 * After stopping journal:
300 	 */
301 	for_each_member_device(c, ca)
302 		bch2_dev_allocator_remove(c, ca);
303 }
304 
305 #ifndef BCH_WRITE_REF_DEBUG
306 static void bch2_writes_disabled(struct percpu_ref *writes)
307 {
308 	struct bch_fs *c = container_of(writes, struct bch_fs, writes);
309 
310 	set_bit(BCH_FS_write_disable_complete, &c->flags);
311 	wake_up(&bch2_read_only_wait);
312 }
313 #endif
314 
315 void bch2_fs_read_only(struct bch_fs *c)
316 {
317 	if (!test_bit(BCH_FS_rw, &c->flags)) {
318 		bch2_journal_reclaim_stop(&c->journal);
319 		return;
320 	}
321 
322 	BUG_ON(test_bit(BCH_FS_write_disable_complete, &c->flags));
323 
324 	bch_verbose(c, "going read-only");
325 
326 	/*
327 	 * Block new foreground-end write operations from starting - any new
328 	 * writes will return -EROFS:
329 	 */
330 	set_bit(BCH_FS_going_ro, &c->flags);
331 #ifndef BCH_WRITE_REF_DEBUG
332 	percpu_ref_kill(&c->writes);
333 #else
334 	for (unsigned i = 0; i < BCH_WRITE_REF_NR; i++)
335 		bch2_write_ref_put(c, i);
336 #endif
337 
338 	/*
339 	 * If we're not doing an emergency shutdown, we want to wait on
340 	 * outstanding writes to complete so they don't see spurious errors due
341 	 * to shutting down the allocator:
342 	 *
343 	 * If we are doing an emergency shutdown outstanding writes may
344 	 * hang until we shutdown the allocator so we don't want to wait
345 	 * on outstanding writes before shutting everything down - but
346 	 * we do need to wait on them before returning and signalling
347 	 * that going RO is complete:
348 	 */
349 	wait_event(bch2_read_only_wait,
350 		   test_bit(BCH_FS_write_disable_complete, &c->flags) ||
351 		   test_bit(BCH_FS_emergency_ro, &c->flags));
352 
353 	bool writes_disabled = test_bit(BCH_FS_write_disable_complete, &c->flags);
354 	if (writes_disabled)
355 		bch_verbose(c, "finished waiting for writes to stop");
356 
357 	__bch2_fs_read_only(c);
358 
359 	wait_event(bch2_read_only_wait,
360 		   test_bit(BCH_FS_write_disable_complete, &c->flags));
361 
362 	if (!writes_disabled)
363 		bch_verbose(c, "finished waiting for writes to stop");
364 
365 	clear_bit(BCH_FS_write_disable_complete, &c->flags);
366 	clear_bit(BCH_FS_going_ro, &c->flags);
367 	clear_bit(BCH_FS_rw, &c->flags);
368 
369 	if (!bch2_journal_error(&c->journal) &&
370 	    !test_bit(BCH_FS_error, &c->flags) &&
371 	    !test_bit(BCH_FS_emergency_ro, &c->flags) &&
372 	    test_bit(BCH_FS_started, &c->flags) &&
373 	    test_bit(BCH_FS_clean_shutdown, &c->flags) &&
374 	    c->recovery_pass_done >= BCH_RECOVERY_PASS_journal_replay) {
375 		BUG_ON(c->journal.last_empty_seq != journal_cur_seq(&c->journal));
376 		BUG_ON(atomic_read(&c->btree_cache.dirty));
377 		BUG_ON(atomic_long_read(&c->btree_key_cache.nr_dirty));
378 		BUG_ON(c->btree_write_buffer.inc.keys.nr);
379 		BUG_ON(c->btree_write_buffer.flushing.keys.nr);
380 
381 		bch_verbose(c, "marking filesystem clean");
382 		bch2_fs_mark_clean(c);
383 	} else {
384 		bch_verbose(c, "done going read-only, filesystem not clean");
385 	}
386 }
387 
388 static void bch2_fs_read_only_work(struct work_struct *work)
389 {
390 	struct bch_fs *c =
391 		container_of(work, struct bch_fs, read_only_work);
392 
393 	down_write(&c->state_lock);
394 	bch2_fs_read_only(c);
395 	up_write(&c->state_lock);
396 }
397 
398 static void bch2_fs_read_only_async(struct bch_fs *c)
399 {
400 	queue_work(system_long_wq, &c->read_only_work);
401 }
402 
403 bool bch2_fs_emergency_read_only(struct bch_fs *c)
404 {
405 	bool ret = !test_and_set_bit(BCH_FS_emergency_ro, &c->flags);
406 
407 	bch2_journal_halt(&c->journal);
408 	bch2_fs_read_only_async(c);
409 
410 	wake_up(&bch2_read_only_wait);
411 	return ret;
412 }
413 
414 static int bch2_fs_read_write_late(struct bch_fs *c)
415 {
416 	int ret;
417 
418 	/*
419 	 * Data move operations can't run until after check_snapshots has
420 	 * completed, and bch2_snapshot_is_ancestor() is available.
421 	 *
422 	 * Ideally we'd start copygc/rebalance earlier instead of waiting for
423 	 * all of recovery/fsck to complete:
424 	 */
425 	ret = bch2_copygc_start(c);
426 	if (ret) {
427 		bch_err(c, "error starting copygc thread");
428 		return ret;
429 	}
430 
431 	ret = bch2_rebalance_start(c);
432 	if (ret) {
433 		bch_err(c, "error starting rebalance thread");
434 		return ret;
435 	}
436 
437 	return 0;
438 }
439 
440 static int __bch2_fs_read_write(struct bch_fs *c, bool early)
441 {
442 	int ret;
443 
444 	if (test_bit(BCH_FS_initial_gc_unfixed, &c->flags)) {
445 		bch_err(c, "cannot go rw, unfixed btree errors");
446 		return -BCH_ERR_erofs_unfixed_errors;
447 	}
448 
449 	if (test_bit(BCH_FS_rw, &c->flags))
450 		return 0;
451 
452 	bch_info(c, "going read-write");
453 
454 	ret = bch2_sb_members_v2_init(c);
455 	if (ret)
456 		goto err;
457 
458 	ret = bch2_fs_mark_dirty(c);
459 	if (ret)
460 		goto err;
461 
462 	clear_bit(BCH_FS_clean_shutdown, &c->flags);
463 
464 	/*
465 	 * First journal write must be a flush write: after a clean shutdown we
466 	 * don't read the journal, so the first journal write may end up
467 	 * overwriting whatever was there previously, and there must always be
468 	 * at least one non-flush write in the journal or recovery will fail:
469 	 */
470 	set_bit(JOURNAL_NEED_FLUSH_WRITE, &c->journal.flags);
471 
472 	for_each_rw_member(c, ca)
473 		bch2_dev_allocator_add(c, ca);
474 	bch2_recalc_capacity(c);
475 
476 	set_bit(BCH_FS_rw, &c->flags);
477 	set_bit(BCH_FS_was_rw, &c->flags);
478 
479 #ifndef BCH_WRITE_REF_DEBUG
480 	percpu_ref_reinit(&c->writes);
481 #else
482 	for (unsigned i = 0; i < BCH_WRITE_REF_NR; i++) {
483 		BUG_ON(atomic_long_read(&c->writes[i]));
484 		atomic_long_inc(&c->writes[i]);
485 	}
486 #endif
487 
488 	ret = bch2_gc_thread_start(c);
489 	if (ret) {
490 		bch_err(c, "error starting gc thread");
491 		return ret;
492 	}
493 
494 	ret = bch2_journal_reclaim_start(&c->journal);
495 	if (ret)
496 		goto err;
497 
498 	if (!early) {
499 		ret = bch2_fs_read_write_late(c);
500 		if (ret)
501 			goto err;
502 	}
503 
504 	bch2_do_discards(c);
505 	bch2_do_invalidates(c);
506 	bch2_do_stripe_deletes(c);
507 	bch2_do_pending_node_rewrites(c);
508 	return 0;
509 err:
510 	if (test_bit(BCH_FS_rw, &c->flags))
511 		bch2_fs_read_only(c);
512 	else
513 		__bch2_fs_read_only(c);
514 	return ret;
515 }
516 
517 int bch2_fs_read_write(struct bch_fs *c)
518 {
519 	if (c->opts.recovery_pass_last &&
520 	    c->opts.recovery_pass_last < BCH_RECOVERY_PASS_journal_replay)
521 		return -BCH_ERR_erofs_norecovery;
522 
523 	if (c->opts.nochanges)
524 		return -BCH_ERR_erofs_nochanges;
525 
526 	return __bch2_fs_read_write(c, false);
527 }
528 
529 int bch2_fs_read_write_early(struct bch_fs *c)
530 {
531 	lockdep_assert_held(&c->state_lock);
532 
533 	return __bch2_fs_read_write(c, true);
534 }
535 
536 /* Filesystem startup/shutdown: */
537 
538 static void __bch2_fs_free(struct bch_fs *c)
539 {
540 	unsigned i;
541 
542 	for (i = 0; i < BCH_TIME_STAT_NR; i++)
543 		bch2_time_stats_exit(&c->times[i]);
544 
545 	bch2_find_btree_nodes_exit(&c->found_btree_nodes);
546 	bch2_free_pending_node_rewrites(c);
547 	bch2_fs_allocator_background_exit(c);
548 	bch2_fs_sb_errors_exit(c);
549 	bch2_fs_counters_exit(c);
550 	bch2_fs_snapshots_exit(c);
551 	bch2_fs_quota_exit(c);
552 	bch2_fs_fs_io_direct_exit(c);
553 	bch2_fs_fs_io_buffered_exit(c);
554 	bch2_fs_fsio_exit(c);
555 	bch2_fs_ec_exit(c);
556 	bch2_fs_encryption_exit(c);
557 	bch2_fs_nocow_locking_exit(c);
558 	bch2_fs_io_write_exit(c);
559 	bch2_fs_io_read_exit(c);
560 	bch2_fs_buckets_waiting_for_journal_exit(c);
561 	bch2_fs_btree_interior_update_exit(c);
562 	bch2_fs_btree_iter_exit(c);
563 	bch2_fs_btree_key_cache_exit(&c->btree_key_cache);
564 	bch2_fs_btree_cache_exit(c);
565 	bch2_fs_replicas_exit(c);
566 	bch2_fs_journal_exit(&c->journal);
567 	bch2_io_clock_exit(&c->io_clock[WRITE]);
568 	bch2_io_clock_exit(&c->io_clock[READ]);
569 	bch2_fs_compress_exit(c);
570 	bch2_journal_keys_put_initial(c);
571 	bch2_find_btree_nodes_exit(&c->found_btree_nodes);
572 	BUG_ON(atomic_read(&c->journal_keys.ref));
573 	bch2_fs_btree_write_buffer_exit(c);
574 	percpu_free_rwsem(&c->mark_lock);
575 	free_percpu(c->online_reserved);
576 
577 	darray_exit(&c->btree_roots_extra);
578 	free_percpu(c->pcpu);
579 	mempool_exit(&c->large_bkey_pool);
580 	mempool_exit(&c->btree_bounce_pool);
581 	bioset_exit(&c->btree_bio);
582 	mempool_exit(&c->fill_iter);
583 #ifndef BCH_WRITE_REF_DEBUG
584 	percpu_ref_exit(&c->writes);
585 #endif
586 	kfree(rcu_dereference_protected(c->disk_groups, 1));
587 	kfree(c->journal_seq_blacklist_table);
588 	kfree(c->unused_inode_hints);
589 
590 	if (c->write_ref_wq)
591 		destroy_workqueue(c->write_ref_wq);
592 	if (c->io_complete_wq)
593 		destroy_workqueue(c->io_complete_wq);
594 	if (c->copygc_wq)
595 		destroy_workqueue(c->copygc_wq);
596 	if (c->btree_io_complete_wq)
597 		destroy_workqueue(c->btree_io_complete_wq);
598 	if (c->btree_update_wq)
599 		destroy_workqueue(c->btree_update_wq);
600 
601 	bch2_free_super(&c->disk_sb);
602 	kvfree(c);
603 	module_put(THIS_MODULE);
604 }
605 
606 static void bch2_fs_release(struct kobject *kobj)
607 {
608 	struct bch_fs *c = container_of(kobj, struct bch_fs, kobj);
609 
610 	__bch2_fs_free(c);
611 }
612 
613 void __bch2_fs_stop(struct bch_fs *c)
614 {
615 	bch_verbose(c, "shutting down");
616 
617 	set_bit(BCH_FS_stopping, &c->flags);
618 
619 	cancel_work_sync(&c->journal_seq_blacklist_gc_work);
620 
621 	down_write(&c->state_lock);
622 	bch2_fs_read_only(c);
623 	up_write(&c->state_lock);
624 
625 	for_each_member_device(c, ca)
626 		if (ca->kobj.state_in_sysfs &&
627 		    ca->disk_sb.bdev)
628 			sysfs_remove_link(bdev_kobj(ca->disk_sb.bdev), "bcachefs");
629 
630 	if (c->kobj.state_in_sysfs)
631 		kobject_del(&c->kobj);
632 
633 	bch2_fs_debug_exit(c);
634 	bch2_fs_chardev_exit(c);
635 
636 	bch2_ro_ref_put(c);
637 	wait_event(c->ro_ref_wait, !refcount_read(&c->ro_ref));
638 
639 	kobject_put(&c->counters_kobj);
640 	kobject_put(&c->time_stats);
641 	kobject_put(&c->opts_dir);
642 	kobject_put(&c->internal);
643 
644 	/* btree prefetch might have kicked off reads in the background: */
645 	bch2_btree_flush_all_reads(c);
646 
647 	for_each_member_device(c, ca)
648 		cancel_work_sync(&ca->io_error_work);
649 
650 	cancel_work_sync(&c->read_only_work);
651 }
652 
653 void bch2_fs_free(struct bch_fs *c)
654 {
655 	unsigned i;
656 
657 	mutex_lock(&bch_fs_list_lock);
658 	list_del(&c->list);
659 	mutex_unlock(&bch_fs_list_lock);
660 
661 	closure_sync(&c->cl);
662 	closure_debug_destroy(&c->cl);
663 
664 	for (i = 0; i < c->sb.nr_devices; i++) {
665 		struct bch_dev *ca = rcu_dereference_protected(c->devs[i], true);
666 
667 		if (ca) {
668 			bch2_free_super(&ca->disk_sb);
669 			bch2_dev_free(ca);
670 		}
671 	}
672 
673 	bch_verbose(c, "shutdown complete");
674 
675 	kobject_put(&c->kobj);
676 }
677 
678 void bch2_fs_stop(struct bch_fs *c)
679 {
680 	__bch2_fs_stop(c);
681 	bch2_fs_free(c);
682 }
683 
684 static int bch2_fs_online(struct bch_fs *c)
685 {
686 	int ret = 0;
687 
688 	lockdep_assert_held(&bch_fs_list_lock);
689 
690 	if (__bch2_uuid_to_fs(c->sb.uuid)) {
691 		bch_err(c, "filesystem UUID already open");
692 		return -EINVAL;
693 	}
694 
695 	ret = bch2_fs_chardev_init(c);
696 	if (ret) {
697 		bch_err(c, "error creating character device");
698 		return ret;
699 	}
700 
701 	bch2_fs_debug_init(c);
702 
703 	ret = kobject_add(&c->kobj, NULL, "%pU", c->sb.user_uuid.b) ?:
704 	    kobject_add(&c->internal, &c->kobj, "internal") ?:
705 	    kobject_add(&c->opts_dir, &c->kobj, "options") ?:
706 #ifndef CONFIG_BCACHEFS_NO_LATENCY_ACCT
707 	    kobject_add(&c->time_stats, &c->kobj, "time_stats") ?:
708 #endif
709 	    kobject_add(&c->counters_kobj, &c->kobj, "counters") ?:
710 	    bch2_opts_create_sysfs_files(&c->opts_dir);
711 	if (ret) {
712 		bch_err(c, "error creating sysfs objects");
713 		return ret;
714 	}
715 
716 	down_write(&c->state_lock);
717 
718 	for_each_member_device(c, ca) {
719 		ret = bch2_dev_sysfs_online(c, ca);
720 		if (ret) {
721 			bch_err(c, "error creating sysfs objects");
722 			percpu_ref_put(&ca->ref);
723 			goto err;
724 		}
725 	}
726 
727 	BUG_ON(!list_empty(&c->list));
728 	list_add(&c->list, &bch_fs_list);
729 err:
730 	up_write(&c->state_lock);
731 	return ret;
732 }
733 
734 static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
735 {
736 	struct bch_fs *c;
737 	struct printbuf name = PRINTBUF;
738 	unsigned i, iter_size;
739 	int ret = 0;
740 
741 	c = kvmalloc(sizeof(struct bch_fs), GFP_KERNEL|__GFP_ZERO);
742 	if (!c) {
743 		c = ERR_PTR(-BCH_ERR_ENOMEM_fs_alloc);
744 		goto out;
745 	}
746 
747 	c->stdio = (void *)(unsigned long) opts.stdio;
748 
749 	__module_get(THIS_MODULE);
750 
751 	closure_init(&c->cl, NULL);
752 
753 	c->kobj.kset = bcachefs_kset;
754 	kobject_init(&c->kobj, &bch2_fs_ktype);
755 	kobject_init(&c->internal, &bch2_fs_internal_ktype);
756 	kobject_init(&c->opts_dir, &bch2_fs_opts_dir_ktype);
757 	kobject_init(&c->time_stats, &bch2_fs_time_stats_ktype);
758 	kobject_init(&c->counters_kobj, &bch2_fs_counters_ktype);
759 
760 	c->minor		= -1;
761 	c->disk_sb.fs_sb	= true;
762 
763 	init_rwsem(&c->state_lock);
764 	mutex_init(&c->sb_lock);
765 	mutex_init(&c->replicas_gc_lock);
766 	mutex_init(&c->btree_root_lock);
767 	INIT_WORK(&c->read_only_work, bch2_fs_read_only_work);
768 
769 	refcount_set(&c->ro_ref, 1);
770 	init_waitqueue_head(&c->ro_ref_wait);
771 	sema_init(&c->online_fsck_mutex, 1);
772 
773 	init_rwsem(&c->gc_lock);
774 	mutex_init(&c->gc_gens_lock);
775 	atomic_set(&c->journal_keys.ref, 1);
776 	c->journal_keys.initial_ref_held = true;
777 
778 	for (i = 0; i < BCH_TIME_STAT_NR; i++)
779 		bch2_time_stats_init(&c->times[i]);
780 
781 	bch2_fs_copygc_init(c);
782 	bch2_fs_btree_key_cache_init_early(&c->btree_key_cache);
783 	bch2_fs_btree_iter_init_early(c);
784 	bch2_fs_btree_interior_update_init_early(c);
785 	bch2_fs_allocator_background_init(c);
786 	bch2_fs_allocator_foreground_init(c);
787 	bch2_fs_rebalance_init(c);
788 	bch2_fs_quota_init(c);
789 	bch2_fs_ec_init_early(c);
790 	bch2_fs_move_init(c);
791 	bch2_fs_sb_errors_init_early(c);
792 
793 	INIT_LIST_HEAD(&c->list);
794 
795 	mutex_init(&c->usage_scratch_lock);
796 
797 	mutex_init(&c->bio_bounce_pages_lock);
798 	mutex_init(&c->snapshot_table_lock);
799 	init_rwsem(&c->snapshot_create_lock);
800 
801 	spin_lock_init(&c->btree_write_error_lock);
802 
803 	INIT_WORK(&c->journal_seq_blacklist_gc_work,
804 		  bch2_blacklist_entries_gc);
805 
806 	INIT_LIST_HEAD(&c->journal_iters);
807 
808 	INIT_LIST_HEAD(&c->fsck_error_msgs);
809 	mutex_init(&c->fsck_error_msgs_lock);
810 
811 	seqcount_init(&c->gc_pos_lock);
812 
813 	seqcount_init(&c->usage_lock);
814 
815 	sema_init(&c->io_in_flight, 128);
816 
817 	INIT_LIST_HEAD(&c->vfs_inodes_list);
818 	mutex_init(&c->vfs_inodes_lock);
819 
820 	c->copy_gc_enabled		= 1;
821 	c->rebalance.enabled		= 1;
822 	c->promote_whole_extents	= true;
823 
824 	c->journal.flush_write_time	= &c->times[BCH_TIME_journal_flush_write];
825 	c->journal.noflush_write_time	= &c->times[BCH_TIME_journal_noflush_write];
826 	c->journal.flush_seq_time	= &c->times[BCH_TIME_journal_flush_seq];
827 
828 	bch2_fs_btree_cache_init_early(&c->btree_cache);
829 
830 	mutex_init(&c->sectors_available_lock);
831 
832 	ret = percpu_init_rwsem(&c->mark_lock);
833 	if (ret)
834 		goto err;
835 
836 	mutex_lock(&c->sb_lock);
837 	ret = bch2_sb_to_fs(c, sb);
838 	mutex_unlock(&c->sb_lock);
839 
840 	if (ret)
841 		goto err;
842 
843 	pr_uuid(&name, c->sb.user_uuid.b);
844 	ret = name.allocation_failure ? -BCH_ERR_ENOMEM_fs_name_alloc : 0;
845 	if (ret)
846 		goto err;
847 
848 	strscpy(c->name, name.buf, sizeof(c->name));
849 	printbuf_exit(&name);
850 
851 	/* Compat: */
852 	if (le16_to_cpu(sb->version) <= bcachefs_metadata_version_inode_v2 &&
853 	    !BCH_SB_JOURNAL_FLUSH_DELAY(sb))
854 		SET_BCH_SB_JOURNAL_FLUSH_DELAY(sb, 1000);
855 
856 	if (le16_to_cpu(sb->version) <= bcachefs_metadata_version_inode_v2 &&
857 	    !BCH_SB_JOURNAL_RECLAIM_DELAY(sb))
858 		SET_BCH_SB_JOURNAL_RECLAIM_DELAY(sb, 100);
859 
860 	c->opts = bch2_opts_default;
861 	ret = bch2_opts_from_sb(&c->opts, sb);
862 	if (ret)
863 		goto err;
864 
865 	bch2_opts_apply(&c->opts, opts);
866 
867 	c->btree_key_cache_btrees |= 1U << BTREE_ID_alloc;
868 	if (c->opts.inodes_use_key_cache)
869 		c->btree_key_cache_btrees |= 1U << BTREE_ID_inodes;
870 	c->btree_key_cache_btrees |= 1U << BTREE_ID_logged_ops;
871 
872 	c->block_bits		= ilog2(block_sectors(c));
873 	c->btree_foreground_merge_threshold = BTREE_FOREGROUND_MERGE_THRESHOLD(c);
874 
875 	if (bch2_fs_init_fault("fs_alloc")) {
876 		bch_err(c, "fs_alloc fault injected");
877 		ret = -EFAULT;
878 		goto err;
879 	}
880 
881 	iter_size = sizeof(struct sort_iter) +
882 		(btree_blocks(c) + 1) * 2 *
883 		sizeof(struct sort_iter_set);
884 
885 	c->inode_shard_bits = ilog2(roundup_pow_of_two(num_possible_cpus()));
886 
887 	if (!(c->btree_update_wq = alloc_workqueue("bcachefs",
888 				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM|WQ_UNBOUND, 512)) ||
889 	    !(c->btree_io_complete_wq = alloc_workqueue("bcachefs_btree_io",
890 				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM, 1)) ||
891 	    !(c->copygc_wq = alloc_workqueue("bcachefs_copygc",
892 				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE, 1)) ||
893 	    !(c->io_complete_wq = alloc_workqueue("bcachefs_io",
894 				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM, 512)) ||
895 	    !(c->write_ref_wq = alloc_workqueue("bcachefs_write_ref",
896 				WQ_FREEZABLE, 0)) ||
897 #ifndef BCH_WRITE_REF_DEBUG
898 	    percpu_ref_init(&c->writes, bch2_writes_disabled,
899 			    PERCPU_REF_INIT_DEAD, GFP_KERNEL) ||
900 #endif
901 	    mempool_init_kmalloc_pool(&c->fill_iter, 1, iter_size) ||
902 	    bioset_init(&c->btree_bio, 1,
903 			max(offsetof(struct btree_read_bio, bio),
904 			    offsetof(struct btree_write_bio, wbio.bio)),
905 			BIOSET_NEED_BVECS) ||
906 	    !(c->pcpu = alloc_percpu(struct bch_fs_pcpu)) ||
907 	    !(c->online_reserved = alloc_percpu(u64)) ||
908 	    mempool_init_kvmalloc_pool(&c->btree_bounce_pool, 1,
909 				       c->opts.btree_node_size) ||
910 	    mempool_init_kmalloc_pool(&c->large_bkey_pool, 1, 2048) ||
911 	    !(c->unused_inode_hints = kcalloc(1U << c->inode_shard_bits,
912 					      sizeof(u64), GFP_KERNEL))) {
913 		ret = -BCH_ERR_ENOMEM_fs_other_alloc;
914 		goto err;
915 	}
916 
917 	ret = bch2_fs_counters_init(c) ?:
918 	    bch2_fs_sb_errors_init(c) ?:
919 	    bch2_io_clock_init(&c->io_clock[READ]) ?:
920 	    bch2_io_clock_init(&c->io_clock[WRITE]) ?:
921 	    bch2_fs_journal_init(&c->journal) ?:
922 	    bch2_fs_replicas_init(c) ?:
923 	    bch2_fs_btree_cache_init(c) ?:
924 	    bch2_fs_btree_key_cache_init(&c->btree_key_cache) ?:
925 	    bch2_fs_btree_iter_init(c) ?:
926 	    bch2_fs_btree_interior_update_init(c) ?:
927 	    bch2_fs_buckets_waiting_for_journal_init(c) ?:
928 	    bch2_fs_btree_write_buffer_init(c) ?:
929 	    bch2_fs_subvolumes_init(c) ?:
930 	    bch2_fs_io_read_init(c) ?:
931 	    bch2_fs_io_write_init(c) ?:
932 	    bch2_fs_nocow_locking_init(c) ?:
933 	    bch2_fs_encryption_init(c) ?:
934 	    bch2_fs_compress_init(c) ?:
935 	    bch2_fs_ec_init(c) ?:
936 	    bch2_fs_fsio_init(c) ?:
937 	    bch2_fs_fs_io_buffered_init(c) ?:
938 	    bch2_fs_fs_io_direct_init(c);
939 	if (ret)
940 		goto err;
941 
942 	for (i = 0; i < c->sb.nr_devices; i++)
943 		if (bch2_dev_exists(c->disk_sb.sb, i) &&
944 		    bch2_dev_alloc(c, i)) {
945 			ret = -EEXIST;
946 			goto err;
947 		}
948 
949 	bch2_journal_entry_res_resize(&c->journal,
950 			&c->btree_root_journal_res,
951 			BTREE_ID_NR * (JSET_KEYS_U64s + BKEY_BTREE_PTR_U64s_MAX));
952 	bch2_dev_usage_journal_reserve(c);
953 	bch2_journal_entry_res_resize(&c->journal,
954 			&c->clock_journal_res,
955 			(sizeof(struct jset_entry_clock) / sizeof(u64)) * 2);
956 
957 	mutex_lock(&bch_fs_list_lock);
958 	ret = bch2_fs_online(c);
959 	mutex_unlock(&bch_fs_list_lock);
960 
961 	if (ret)
962 		goto err;
963 out:
964 	return c;
965 err:
966 	bch2_fs_free(c);
967 	c = ERR_PTR(ret);
968 	goto out;
969 }
970 
971 noinline_for_stack
972 static void print_mount_opts(struct bch_fs *c)
973 {
974 	enum bch_opt_id i;
975 	struct printbuf p = PRINTBUF;
976 	bool first = true;
977 
978 	prt_str(&p, "mounting version ");
979 	bch2_version_to_text(&p, c->sb.version);
980 
981 	if (c->opts.read_only) {
982 		prt_str(&p, " opts=");
983 		first = false;
984 		prt_printf(&p, "ro");
985 	}
986 
987 	for (i = 0; i < bch2_opts_nr; i++) {
988 		const struct bch_option *opt = &bch2_opt_table[i];
989 		u64 v = bch2_opt_get_by_id(&c->opts, i);
990 
991 		if (!(opt->flags & OPT_MOUNT))
992 			continue;
993 
994 		if (v == bch2_opt_get_by_id(&bch2_opts_default, i))
995 			continue;
996 
997 		prt_str(&p, first ? " opts=" : ",");
998 		first = false;
999 		bch2_opt_to_text(&p, c, c->disk_sb.sb, opt, v, OPT_SHOW_MOUNT_STYLE);
1000 	}
1001 
1002 	bch_info(c, "%s", p.buf);
1003 	printbuf_exit(&p);
1004 }
1005 
1006 int bch2_fs_start(struct bch_fs *c)
1007 {
1008 	time64_t now = ktime_get_real_seconds();
1009 	int ret;
1010 
1011 	print_mount_opts(c);
1012 
1013 	down_write(&c->state_lock);
1014 
1015 	BUG_ON(test_bit(BCH_FS_started, &c->flags));
1016 
1017 	mutex_lock(&c->sb_lock);
1018 
1019 	ret = bch2_sb_members_v2_init(c);
1020 	if (ret) {
1021 		mutex_unlock(&c->sb_lock);
1022 		goto err;
1023 	}
1024 
1025 	for_each_online_member(c, ca)
1026 		bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx)->last_mount = cpu_to_le64(now);
1027 
1028 	struct bch_sb_field_ext *ext =
1029 		bch2_sb_field_get_minsize(&c->disk_sb, ext, sizeof(*ext) / sizeof(u64));
1030 	mutex_unlock(&c->sb_lock);
1031 
1032 	if (!ext) {
1033 		bch_err(c, "insufficient space in superblock for sb_field_ext");
1034 		ret = -BCH_ERR_ENOSPC_sb;
1035 		goto err;
1036 	}
1037 
1038 	for_each_rw_member(c, ca)
1039 		bch2_dev_allocator_add(c, ca);
1040 	bch2_recalc_capacity(c);
1041 
1042 	ret = BCH_SB_INITIALIZED(c->disk_sb.sb)
1043 		? bch2_fs_recovery(c)
1044 		: bch2_fs_initialize(c);
1045 	if (ret)
1046 		goto err;
1047 
1048 	ret = bch2_opts_check_may_set(c);
1049 	if (ret)
1050 		goto err;
1051 
1052 	if (bch2_fs_init_fault("fs_start")) {
1053 		bch_err(c, "fs_start fault injected");
1054 		ret = -EINVAL;
1055 		goto err;
1056 	}
1057 
1058 	set_bit(BCH_FS_started, &c->flags);
1059 
1060 	if (c->opts.read_only) {
1061 		bch2_fs_read_only(c);
1062 	} else {
1063 		ret = !test_bit(BCH_FS_rw, &c->flags)
1064 			? bch2_fs_read_write(c)
1065 			: bch2_fs_read_write_late(c);
1066 		if (ret)
1067 			goto err;
1068 	}
1069 
1070 	ret = 0;
1071 err:
1072 	if (ret)
1073 		bch_err_msg(c, ret, "starting filesystem");
1074 	else
1075 		bch_verbose(c, "done starting filesystem");
1076 	up_write(&c->state_lock);
1077 	return ret;
1078 }
1079 
1080 static int bch2_dev_may_add(struct bch_sb *sb, struct bch_fs *c)
1081 {
1082 	struct bch_member m = bch2_sb_member_get(sb, sb->dev_idx);
1083 
1084 	if (le16_to_cpu(sb->block_size) != block_sectors(c))
1085 		return -BCH_ERR_mismatched_block_size;
1086 
1087 	if (le16_to_cpu(m.bucket_size) <
1088 	    BCH_SB_BTREE_NODE_SIZE(c->disk_sb.sb))
1089 		return -BCH_ERR_bucket_size_too_small;
1090 
1091 	return 0;
1092 }
1093 
1094 static int bch2_dev_in_fs(struct bch_sb_handle *fs,
1095 			  struct bch_sb_handle *sb,
1096 			  struct bch_opts *opts)
1097 {
1098 	if (fs == sb)
1099 		return 0;
1100 
1101 	if (!uuid_equal(&fs->sb->uuid, &sb->sb->uuid))
1102 		return -BCH_ERR_device_not_a_member_of_filesystem;
1103 
1104 	if (!bch2_dev_exists(fs->sb, sb->sb->dev_idx))
1105 		return -BCH_ERR_device_has_been_removed;
1106 
1107 	if (fs->sb->block_size != sb->sb->block_size)
1108 		return -BCH_ERR_mismatched_block_size;
1109 
1110 	if (le16_to_cpu(fs->sb->version) < bcachefs_metadata_version_member_seq ||
1111 	    le16_to_cpu(sb->sb->version) < bcachefs_metadata_version_member_seq)
1112 		return 0;
1113 
1114 	if (fs->sb->seq == sb->sb->seq &&
1115 	    fs->sb->write_time != sb->sb->write_time) {
1116 		struct printbuf buf = PRINTBUF;
1117 
1118 		prt_str(&buf, "Split brain detected between ");
1119 		prt_bdevname(&buf, sb->bdev);
1120 		prt_str(&buf, " and ");
1121 		prt_bdevname(&buf, fs->bdev);
1122 		prt_char(&buf, ':');
1123 		prt_newline(&buf);
1124 		prt_printf(&buf, "seq=%llu but write_time different, got", le64_to_cpu(sb->sb->seq));
1125 		prt_newline(&buf);
1126 
1127 		prt_bdevname(&buf, fs->bdev);
1128 		prt_char(&buf, ' ');
1129 		bch2_prt_datetime(&buf, le64_to_cpu(fs->sb->write_time));;
1130 		prt_newline(&buf);
1131 
1132 		prt_bdevname(&buf, sb->bdev);
1133 		prt_char(&buf, ' ');
1134 		bch2_prt_datetime(&buf, le64_to_cpu(sb->sb->write_time));;
1135 		prt_newline(&buf);
1136 
1137 		if (!opts->no_splitbrain_check)
1138 			prt_printf(&buf, "Not using older sb");
1139 
1140 		pr_err("%s", buf.buf);
1141 		printbuf_exit(&buf);
1142 
1143 		if (!opts->no_splitbrain_check)
1144 			return -BCH_ERR_device_splitbrain;
1145 	}
1146 
1147 	struct bch_member m = bch2_sb_member_get(fs->sb, sb->sb->dev_idx);
1148 	u64 seq_from_fs		= le64_to_cpu(m.seq);
1149 	u64 seq_from_member	= le64_to_cpu(sb->sb->seq);
1150 
1151 	if (seq_from_fs && seq_from_fs < seq_from_member) {
1152 		struct printbuf buf = PRINTBUF;
1153 
1154 		prt_str(&buf, "Split brain detected between ");
1155 		prt_bdevname(&buf, sb->bdev);
1156 		prt_str(&buf, " and ");
1157 		prt_bdevname(&buf, fs->bdev);
1158 		prt_char(&buf, ':');
1159 		prt_newline(&buf);
1160 
1161 		prt_bdevname(&buf, fs->bdev);
1162 		prt_str(&buf, " believes seq of ");
1163 		prt_bdevname(&buf, sb->bdev);
1164 		prt_printf(&buf, " to be %llu, but ", seq_from_fs);
1165 		prt_bdevname(&buf, sb->bdev);
1166 		prt_printf(&buf, " has %llu\n", seq_from_member);
1167 
1168 		if (!opts->no_splitbrain_check) {
1169 			prt_str(&buf, "Not using ");
1170 			prt_bdevname(&buf, sb->bdev);
1171 		}
1172 
1173 		pr_err("%s", buf.buf);
1174 		printbuf_exit(&buf);
1175 
1176 		if (!opts->no_splitbrain_check)
1177 			return -BCH_ERR_device_splitbrain;
1178 	}
1179 
1180 	return 0;
1181 }
1182 
1183 /* Device startup/shutdown: */
1184 
1185 static void bch2_dev_release(struct kobject *kobj)
1186 {
1187 	struct bch_dev *ca = container_of(kobj, struct bch_dev, kobj);
1188 
1189 	kfree(ca);
1190 }
1191 
1192 static void bch2_dev_free(struct bch_dev *ca)
1193 {
1194 	cancel_work_sync(&ca->io_error_work);
1195 
1196 	if (ca->kobj.state_in_sysfs &&
1197 	    ca->disk_sb.bdev)
1198 		sysfs_remove_link(bdev_kobj(ca->disk_sb.bdev), "bcachefs");
1199 
1200 	if (ca->kobj.state_in_sysfs)
1201 		kobject_del(&ca->kobj);
1202 
1203 	bch2_free_super(&ca->disk_sb);
1204 	bch2_dev_journal_exit(ca);
1205 
1206 	free_percpu(ca->io_done);
1207 	bioset_exit(&ca->replica_set);
1208 	bch2_dev_buckets_free(ca);
1209 	free_page((unsigned long) ca->sb_read_scratch);
1210 
1211 	bch2_time_stats_quantiles_exit(&ca->io_latency[WRITE]);
1212 	bch2_time_stats_quantiles_exit(&ca->io_latency[READ]);
1213 
1214 	percpu_ref_exit(&ca->io_ref);
1215 	percpu_ref_exit(&ca->ref);
1216 	kobject_put(&ca->kobj);
1217 }
1218 
1219 static void __bch2_dev_offline(struct bch_fs *c, struct bch_dev *ca)
1220 {
1221 
1222 	lockdep_assert_held(&c->state_lock);
1223 
1224 	if (percpu_ref_is_zero(&ca->io_ref))
1225 		return;
1226 
1227 	__bch2_dev_read_only(c, ca);
1228 
1229 	reinit_completion(&ca->io_ref_completion);
1230 	percpu_ref_kill(&ca->io_ref);
1231 	wait_for_completion(&ca->io_ref_completion);
1232 
1233 	if (ca->kobj.state_in_sysfs) {
1234 		sysfs_remove_link(bdev_kobj(ca->disk_sb.bdev), "bcachefs");
1235 		sysfs_remove_link(&ca->kobj, "block");
1236 	}
1237 
1238 	bch2_free_super(&ca->disk_sb);
1239 	bch2_dev_journal_exit(ca);
1240 }
1241 
1242 static void bch2_dev_ref_complete(struct percpu_ref *ref)
1243 {
1244 	struct bch_dev *ca = container_of(ref, struct bch_dev, ref);
1245 
1246 	complete(&ca->ref_completion);
1247 }
1248 
1249 static void bch2_dev_io_ref_complete(struct percpu_ref *ref)
1250 {
1251 	struct bch_dev *ca = container_of(ref, struct bch_dev, io_ref);
1252 
1253 	complete(&ca->io_ref_completion);
1254 }
1255 
1256 static int bch2_dev_sysfs_online(struct bch_fs *c, struct bch_dev *ca)
1257 {
1258 	int ret;
1259 
1260 	if (!c->kobj.state_in_sysfs)
1261 		return 0;
1262 
1263 	if (!ca->kobj.state_in_sysfs) {
1264 		ret = kobject_add(&ca->kobj, &c->kobj,
1265 				  "dev-%u", ca->dev_idx);
1266 		if (ret)
1267 			return ret;
1268 	}
1269 
1270 	if (ca->disk_sb.bdev) {
1271 		struct kobject *block = bdev_kobj(ca->disk_sb.bdev);
1272 
1273 		ret = sysfs_create_link(block, &ca->kobj, "bcachefs");
1274 		if (ret)
1275 			return ret;
1276 
1277 		ret = sysfs_create_link(&ca->kobj, block, "block");
1278 		if (ret)
1279 			return ret;
1280 	}
1281 
1282 	return 0;
1283 }
1284 
1285 static struct bch_dev *__bch2_dev_alloc(struct bch_fs *c,
1286 					struct bch_member *member)
1287 {
1288 	struct bch_dev *ca;
1289 	unsigned i;
1290 
1291 	ca = kzalloc(sizeof(*ca), GFP_KERNEL);
1292 	if (!ca)
1293 		return NULL;
1294 
1295 	kobject_init(&ca->kobj, &bch2_dev_ktype);
1296 	init_completion(&ca->ref_completion);
1297 	init_completion(&ca->io_ref_completion);
1298 
1299 	init_rwsem(&ca->bucket_lock);
1300 
1301 	INIT_WORK(&ca->io_error_work, bch2_io_error_work);
1302 
1303 	bch2_time_stats_quantiles_init(&ca->io_latency[READ]);
1304 	bch2_time_stats_quantiles_init(&ca->io_latency[WRITE]);
1305 
1306 	ca->mi = bch2_mi_to_cpu(member);
1307 
1308 	for (i = 0; i < ARRAY_SIZE(member->errors); i++)
1309 		atomic64_set(&ca->errors[i], le64_to_cpu(member->errors[i]));
1310 
1311 	ca->uuid = member->uuid;
1312 
1313 	ca->nr_btree_reserve = DIV_ROUND_UP(BTREE_NODE_RESERVE,
1314 			     ca->mi.bucket_size / btree_sectors(c));
1315 
1316 	if (percpu_ref_init(&ca->ref, bch2_dev_ref_complete,
1317 			    0, GFP_KERNEL) ||
1318 	    percpu_ref_init(&ca->io_ref, bch2_dev_io_ref_complete,
1319 			    PERCPU_REF_INIT_DEAD, GFP_KERNEL) ||
1320 	    !(ca->sb_read_scratch = (void *) __get_free_page(GFP_KERNEL)) ||
1321 	    bch2_dev_buckets_alloc(c, ca) ||
1322 	    bioset_init(&ca->replica_set, 4,
1323 			offsetof(struct bch_write_bio, bio), 0) ||
1324 	    !(ca->io_done	= alloc_percpu(*ca->io_done)))
1325 		goto err;
1326 
1327 	return ca;
1328 err:
1329 	bch2_dev_free(ca);
1330 	return NULL;
1331 }
1332 
1333 static void bch2_dev_attach(struct bch_fs *c, struct bch_dev *ca,
1334 			    unsigned dev_idx)
1335 {
1336 	ca->dev_idx = dev_idx;
1337 	__set_bit(ca->dev_idx, ca->self.d);
1338 	scnprintf(ca->name, sizeof(ca->name), "dev-%u", dev_idx);
1339 
1340 	ca->fs = c;
1341 	rcu_assign_pointer(c->devs[ca->dev_idx], ca);
1342 
1343 	if (bch2_dev_sysfs_online(c, ca))
1344 		pr_warn("error creating sysfs objects");
1345 }
1346 
1347 static int bch2_dev_alloc(struct bch_fs *c, unsigned dev_idx)
1348 {
1349 	struct bch_member member = bch2_sb_member_get(c->disk_sb.sb, dev_idx);
1350 	struct bch_dev *ca = NULL;
1351 	int ret = 0;
1352 
1353 	if (bch2_fs_init_fault("dev_alloc"))
1354 		goto err;
1355 
1356 	ca = __bch2_dev_alloc(c, &member);
1357 	if (!ca)
1358 		goto err;
1359 
1360 	ca->fs = c;
1361 
1362 	bch2_dev_attach(c, ca, dev_idx);
1363 	return ret;
1364 err:
1365 	if (ca)
1366 		bch2_dev_free(ca);
1367 	return -BCH_ERR_ENOMEM_dev_alloc;
1368 }
1369 
1370 static int __bch2_dev_attach_bdev(struct bch_dev *ca, struct bch_sb_handle *sb)
1371 {
1372 	unsigned ret;
1373 
1374 	if (bch2_dev_is_online(ca)) {
1375 		bch_err(ca, "already have device online in slot %u",
1376 			sb->sb->dev_idx);
1377 		return -BCH_ERR_device_already_online;
1378 	}
1379 
1380 	if (get_capacity(sb->bdev->bd_disk) <
1381 	    ca->mi.bucket_size * ca->mi.nbuckets) {
1382 		bch_err(ca, "cannot online: device too small");
1383 		return -BCH_ERR_device_size_too_small;
1384 	}
1385 
1386 	BUG_ON(!percpu_ref_is_zero(&ca->io_ref));
1387 
1388 	ret = bch2_dev_journal_init(ca, sb->sb);
1389 	if (ret)
1390 		return ret;
1391 
1392 	/* Commit: */
1393 	ca->disk_sb = *sb;
1394 	memset(sb, 0, sizeof(*sb));
1395 
1396 	ca->dev = ca->disk_sb.bdev->bd_dev;
1397 
1398 	percpu_ref_reinit(&ca->io_ref);
1399 
1400 	return 0;
1401 }
1402 
1403 static int bch2_dev_attach_bdev(struct bch_fs *c, struct bch_sb_handle *sb)
1404 {
1405 	struct bch_dev *ca;
1406 	int ret;
1407 
1408 	lockdep_assert_held(&c->state_lock);
1409 
1410 	if (le64_to_cpu(sb->sb->seq) >
1411 	    le64_to_cpu(c->disk_sb.sb->seq))
1412 		bch2_sb_to_fs(c, sb->sb);
1413 
1414 	BUG_ON(sb->sb->dev_idx >= c->sb.nr_devices ||
1415 	       !c->devs[sb->sb->dev_idx]);
1416 
1417 	ca = bch_dev_locked(c, sb->sb->dev_idx);
1418 
1419 	ret = __bch2_dev_attach_bdev(ca, sb);
1420 	if (ret)
1421 		return ret;
1422 
1423 	bch2_dev_sysfs_online(c, ca);
1424 
1425 	struct printbuf name = PRINTBUF;
1426 	prt_bdevname(&name, ca->disk_sb.bdev);
1427 
1428 	if (c->sb.nr_devices == 1)
1429 		strscpy(c->name, name.buf, sizeof(c->name));
1430 	strscpy(ca->name, name.buf, sizeof(ca->name));
1431 
1432 	printbuf_exit(&name);
1433 
1434 	rebalance_wakeup(c);
1435 	return 0;
1436 }
1437 
1438 /* Device management: */
1439 
1440 /*
1441  * Note: this function is also used by the error paths - when a particular
1442  * device sees an error, we call it to determine whether we can just set the
1443  * device RO, or - if this function returns false - we'll set the whole
1444  * filesystem RO:
1445  *
1446  * XXX: maybe we should be more explicit about whether we're changing state
1447  * because we got an error or what have you?
1448  */
1449 bool bch2_dev_state_allowed(struct bch_fs *c, struct bch_dev *ca,
1450 			    enum bch_member_state new_state, int flags)
1451 {
1452 	struct bch_devs_mask new_online_devs;
1453 	int nr_rw = 0, required;
1454 
1455 	lockdep_assert_held(&c->state_lock);
1456 
1457 	switch (new_state) {
1458 	case BCH_MEMBER_STATE_rw:
1459 		return true;
1460 	case BCH_MEMBER_STATE_ro:
1461 		if (ca->mi.state != BCH_MEMBER_STATE_rw)
1462 			return true;
1463 
1464 		/* do we have enough devices to write to?  */
1465 		for_each_member_device(c, ca2)
1466 			if (ca2 != ca)
1467 				nr_rw += ca2->mi.state == BCH_MEMBER_STATE_rw;
1468 
1469 		required = max(!(flags & BCH_FORCE_IF_METADATA_DEGRADED)
1470 			       ? c->opts.metadata_replicas
1471 			       : metadata_replicas_required(c),
1472 			       !(flags & BCH_FORCE_IF_DATA_DEGRADED)
1473 			       ? c->opts.data_replicas
1474 			       : data_replicas_required(c));
1475 
1476 		return nr_rw >= required;
1477 	case BCH_MEMBER_STATE_failed:
1478 	case BCH_MEMBER_STATE_spare:
1479 		if (ca->mi.state != BCH_MEMBER_STATE_rw &&
1480 		    ca->mi.state != BCH_MEMBER_STATE_ro)
1481 			return true;
1482 
1483 		/* do we have enough devices to read from?  */
1484 		new_online_devs = bch2_online_devs(c);
1485 		__clear_bit(ca->dev_idx, new_online_devs.d);
1486 
1487 		return bch2_have_enough_devs(c, new_online_devs, flags, false);
1488 	default:
1489 		BUG();
1490 	}
1491 }
1492 
1493 static bool bch2_fs_may_start(struct bch_fs *c)
1494 {
1495 	struct bch_dev *ca;
1496 	unsigned i, flags = 0;
1497 
1498 	if (c->opts.very_degraded)
1499 		flags |= BCH_FORCE_IF_DEGRADED|BCH_FORCE_IF_LOST;
1500 
1501 	if (c->opts.degraded)
1502 		flags |= BCH_FORCE_IF_DEGRADED;
1503 
1504 	if (!c->opts.degraded &&
1505 	    !c->opts.very_degraded) {
1506 		mutex_lock(&c->sb_lock);
1507 
1508 		for (i = 0; i < c->disk_sb.sb->nr_devices; i++) {
1509 			if (!bch2_dev_exists(c->disk_sb.sb, i))
1510 				continue;
1511 
1512 			ca = bch_dev_locked(c, i);
1513 
1514 			if (!bch2_dev_is_online(ca) &&
1515 			    (ca->mi.state == BCH_MEMBER_STATE_rw ||
1516 			     ca->mi.state == BCH_MEMBER_STATE_ro)) {
1517 				mutex_unlock(&c->sb_lock);
1518 				return false;
1519 			}
1520 		}
1521 		mutex_unlock(&c->sb_lock);
1522 	}
1523 
1524 	return bch2_have_enough_devs(c, bch2_online_devs(c), flags, true);
1525 }
1526 
1527 static void __bch2_dev_read_only(struct bch_fs *c, struct bch_dev *ca)
1528 {
1529 	/*
1530 	 * The allocator thread itself allocates btree nodes, so stop it first:
1531 	 */
1532 	bch2_dev_allocator_remove(c, ca);
1533 	bch2_dev_journal_stop(&c->journal, ca);
1534 }
1535 
1536 static void __bch2_dev_read_write(struct bch_fs *c, struct bch_dev *ca)
1537 {
1538 	lockdep_assert_held(&c->state_lock);
1539 
1540 	BUG_ON(ca->mi.state != BCH_MEMBER_STATE_rw);
1541 
1542 	bch2_dev_allocator_add(c, ca);
1543 	bch2_recalc_capacity(c);
1544 }
1545 
1546 int __bch2_dev_set_state(struct bch_fs *c, struct bch_dev *ca,
1547 			 enum bch_member_state new_state, int flags)
1548 {
1549 	struct bch_member *m;
1550 	int ret = 0;
1551 
1552 	if (ca->mi.state == new_state)
1553 		return 0;
1554 
1555 	if (!bch2_dev_state_allowed(c, ca, new_state, flags))
1556 		return -BCH_ERR_device_state_not_allowed;
1557 
1558 	if (new_state != BCH_MEMBER_STATE_rw)
1559 		__bch2_dev_read_only(c, ca);
1560 
1561 	bch_notice(ca, "%s", bch2_member_states[new_state]);
1562 
1563 	mutex_lock(&c->sb_lock);
1564 	m = bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx);
1565 	SET_BCH_MEMBER_STATE(m, new_state);
1566 	bch2_write_super(c);
1567 	mutex_unlock(&c->sb_lock);
1568 
1569 	if (new_state == BCH_MEMBER_STATE_rw)
1570 		__bch2_dev_read_write(c, ca);
1571 
1572 	rebalance_wakeup(c);
1573 
1574 	return ret;
1575 }
1576 
1577 int bch2_dev_set_state(struct bch_fs *c, struct bch_dev *ca,
1578 		       enum bch_member_state new_state, int flags)
1579 {
1580 	int ret;
1581 
1582 	down_write(&c->state_lock);
1583 	ret = __bch2_dev_set_state(c, ca, new_state, flags);
1584 	up_write(&c->state_lock);
1585 
1586 	return ret;
1587 }
1588 
1589 /* Device add/removal: */
1590 
1591 static int bch2_dev_remove_alloc(struct bch_fs *c, struct bch_dev *ca)
1592 {
1593 	struct bpos start	= POS(ca->dev_idx, 0);
1594 	struct bpos end		= POS(ca->dev_idx, U64_MAX);
1595 	int ret;
1596 
1597 	/*
1598 	 * We clear the LRU and need_discard btrees first so that we don't race
1599 	 * with bch2_do_invalidates() and bch2_do_discards()
1600 	 */
1601 	ret =   bch2_btree_delete_range(c, BTREE_ID_lru, start, end,
1602 					BTREE_TRIGGER_NORUN, NULL) ?:
1603 		bch2_btree_delete_range(c, BTREE_ID_need_discard, start, end,
1604 					BTREE_TRIGGER_NORUN, NULL) ?:
1605 		bch2_btree_delete_range(c, BTREE_ID_freespace, start, end,
1606 					BTREE_TRIGGER_NORUN, NULL) ?:
1607 		bch2_btree_delete_range(c, BTREE_ID_backpointers, start, end,
1608 					BTREE_TRIGGER_NORUN, NULL) ?:
1609 		bch2_btree_delete_range(c, BTREE_ID_alloc, start, end,
1610 					BTREE_TRIGGER_NORUN, NULL) ?:
1611 		bch2_btree_delete_range(c, BTREE_ID_bucket_gens, start, end,
1612 					BTREE_TRIGGER_NORUN, NULL);
1613 	bch_err_msg(c, ret, "removing dev alloc info");
1614 	return ret;
1615 }
1616 
1617 int bch2_dev_remove(struct bch_fs *c, struct bch_dev *ca, int flags)
1618 {
1619 	struct bch_member *m;
1620 	unsigned dev_idx = ca->dev_idx, data;
1621 	int ret;
1622 
1623 	down_write(&c->state_lock);
1624 
1625 	/*
1626 	 * We consume a reference to ca->ref, regardless of whether we succeed
1627 	 * or fail:
1628 	 */
1629 	percpu_ref_put(&ca->ref);
1630 
1631 	if (!bch2_dev_state_allowed(c, ca, BCH_MEMBER_STATE_failed, flags)) {
1632 		bch_err(ca, "Cannot remove without losing data");
1633 		ret = -BCH_ERR_device_state_not_allowed;
1634 		goto err;
1635 	}
1636 
1637 	__bch2_dev_read_only(c, ca);
1638 
1639 	ret = bch2_dev_data_drop(c, ca->dev_idx, flags);
1640 	bch_err_msg(ca, ret, "bch2_dev_data_drop()");
1641 	if (ret)
1642 		goto err;
1643 
1644 	ret = bch2_dev_remove_alloc(c, ca);
1645 	bch_err_msg(ca, ret, "bch2_dev_remove_alloc()");
1646 	if (ret)
1647 		goto err;
1648 
1649 	ret = bch2_journal_flush_device_pins(&c->journal, ca->dev_idx);
1650 	bch_err_msg(ca, ret, "bch2_journal_flush_device_pins()");
1651 	if (ret)
1652 		goto err;
1653 
1654 	ret = bch2_journal_flush(&c->journal);
1655 	bch_err_msg(ca, ret, "bch2_journal_flush()");
1656 	if (ret)
1657 		goto err;
1658 
1659 	ret = bch2_replicas_gc2(c);
1660 	bch_err_msg(ca, ret, "bch2_replicas_gc2()");
1661 	if (ret)
1662 		goto err;
1663 
1664 	data = bch2_dev_has_data(c, ca);
1665 	if (data) {
1666 		struct printbuf data_has = PRINTBUF;
1667 
1668 		prt_bitflags(&data_has, __bch2_data_types, data);
1669 		bch_err(ca, "Remove failed, still has data (%s)", data_has.buf);
1670 		printbuf_exit(&data_has);
1671 		ret = -EBUSY;
1672 		goto err;
1673 	}
1674 
1675 	__bch2_dev_offline(c, ca);
1676 
1677 	mutex_lock(&c->sb_lock);
1678 	rcu_assign_pointer(c->devs[ca->dev_idx], NULL);
1679 	mutex_unlock(&c->sb_lock);
1680 
1681 	percpu_ref_kill(&ca->ref);
1682 	wait_for_completion(&ca->ref_completion);
1683 
1684 	bch2_dev_free(ca);
1685 
1686 	/*
1687 	 * At this point the device object has been removed in-core, but the
1688 	 * on-disk journal might still refer to the device index via sb device
1689 	 * usage entries. Recovery fails if it sees usage information for an
1690 	 * invalid device. Flush journal pins to push the back of the journal
1691 	 * past now invalid device index references before we update the
1692 	 * superblock, but after the device object has been removed so any
1693 	 * further journal writes elide usage info for the device.
1694 	 */
1695 	bch2_journal_flush_all_pins(&c->journal);
1696 
1697 	/*
1698 	 * Free this device's slot in the bch_member array - all pointers to
1699 	 * this device must be gone:
1700 	 */
1701 	mutex_lock(&c->sb_lock);
1702 	m = bch2_members_v2_get_mut(c->disk_sb.sb, dev_idx);
1703 	memset(&m->uuid, 0, sizeof(m->uuid));
1704 
1705 	bch2_write_super(c);
1706 
1707 	mutex_unlock(&c->sb_lock);
1708 	up_write(&c->state_lock);
1709 
1710 	bch2_dev_usage_journal_reserve(c);
1711 	return 0;
1712 err:
1713 	if (ca->mi.state == BCH_MEMBER_STATE_rw &&
1714 	    !percpu_ref_is_zero(&ca->io_ref))
1715 		__bch2_dev_read_write(c, ca);
1716 	up_write(&c->state_lock);
1717 	return ret;
1718 }
1719 
1720 /* Add new device to running filesystem: */
1721 int bch2_dev_add(struct bch_fs *c, const char *path)
1722 {
1723 	struct bch_opts opts = bch2_opts_empty();
1724 	struct bch_sb_handle sb;
1725 	struct bch_dev *ca = NULL;
1726 	struct bch_sb_field_members_v2 *mi;
1727 	struct bch_member dev_mi;
1728 	unsigned dev_idx, nr_devices, u64s;
1729 	struct printbuf errbuf = PRINTBUF;
1730 	struct printbuf label = PRINTBUF;
1731 	int ret;
1732 
1733 	ret = bch2_read_super(path, &opts, &sb);
1734 	bch_err_msg(c, ret, "reading super");
1735 	if (ret)
1736 		goto err;
1737 
1738 	dev_mi = bch2_sb_member_get(sb.sb, sb.sb->dev_idx);
1739 
1740 	if (BCH_MEMBER_GROUP(&dev_mi)) {
1741 		bch2_disk_path_to_text_sb(&label, sb.sb, BCH_MEMBER_GROUP(&dev_mi) - 1);
1742 		if (label.allocation_failure) {
1743 			ret = -ENOMEM;
1744 			goto err;
1745 		}
1746 	}
1747 
1748 	ret = bch2_dev_may_add(sb.sb, c);
1749 	if (ret)
1750 		goto err;
1751 
1752 	ca = __bch2_dev_alloc(c, &dev_mi);
1753 	if (!ca) {
1754 		ret = -ENOMEM;
1755 		goto err;
1756 	}
1757 
1758 	bch2_dev_usage_init(ca);
1759 
1760 	ret = __bch2_dev_attach_bdev(ca, &sb);
1761 	if (ret)
1762 		goto err;
1763 
1764 	ret = bch2_dev_journal_alloc(ca);
1765 	bch_err_msg(c, ret, "allocating journal");
1766 	if (ret)
1767 		goto err;
1768 
1769 	down_write(&c->state_lock);
1770 	mutex_lock(&c->sb_lock);
1771 
1772 	ret = bch2_sb_from_fs(c, ca);
1773 	bch_err_msg(c, ret, "setting up new superblock");
1774 	if (ret)
1775 		goto err_unlock;
1776 
1777 	if (dynamic_fault("bcachefs:add:no_slot"))
1778 		goto no_slot;
1779 
1780 	for (dev_idx = 0; dev_idx < BCH_SB_MEMBERS_MAX; dev_idx++)
1781 		if (!bch2_dev_exists(c->disk_sb.sb, dev_idx))
1782 			goto have_slot;
1783 no_slot:
1784 	ret = -BCH_ERR_ENOSPC_sb_members;
1785 	bch_err_msg(c, ret, "setting up new superblock");
1786 	goto err_unlock;
1787 
1788 have_slot:
1789 	nr_devices = max_t(unsigned, dev_idx + 1, c->sb.nr_devices);
1790 
1791 	mi = bch2_sb_field_get(c->disk_sb.sb, members_v2);
1792 	u64s = DIV_ROUND_UP(sizeof(struct bch_sb_field_members_v2) +
1793 			    le16_to_cpu(mi->member_bytes) * nr_devices, sizeof(u64));
1794 
1795 	mi = bch2_sb_field_resize(&c->disk_sb, members_v2, u64s);
1796 	if (!mi) {
1797 		ret = -BCH_ERR_ENOSPC_sb_members;
1798 		bch_err_msg(c, ret, "setting up new superblock");
1799 		goto err_unlock;
1800 	}
1801 	struct bch_member *m = bch2_members_v2_get_mut(c->disk_sb.sb, dev_idx);
1802 
1803 	/* success: */
1804 
1805 	*m = dev_mi;
1806 	m->last_mount = cpu_to_le64(ktime_get_real_seconds());
1807 	c->disk_sb.sb->nr_devices	= nr_devices;
1808 
1809 	ca->disk_sb.sb->dev_idx	= dev_idx;
1810 	bch2_dev_attach(c, ca, dev_idx);
1811 
1812 	if (BCH_MEMBER_GROUP(&dev_mi)) {
1813 		ret = __bch2_dev_group_set(c, ca, label.buf);
1814 		bch_err_msg(c, ret, "creating new label");
1815 		if (ret)
1816 			goto err_unlock;
1817 	}
1818 
1819 	bch2_write_super(c);
1820 	mutex_unlock(&c->sb_lock);
1821 
1822 	bch2_dev_usage_journal_reserve(c);
1823 
1824 	ret = bch2_trans_mark_dev_sb(c, ca);
1825 	bch_err_msg(ca, ret, "marking new superblock");
1826 	if (ret)
1827 		goto err_late;
1828 
1829 	ret = bch2_fs_freespace_init(c);
1830 	bch_err_msg(ca, ret, "initializing free space");
1831 	if (ret)
1832 		goto err_late;
1833 
1834 	ca->new_fs_bucket_idx = 0;
1835 
1836 	if (ca->mi.state == BCH_MEMBER_STATE_rw)
1837 		__bch2_dev_read_write(c, ca);
1838 
1839 	up_write(&c->state_lock);
1840 	return 0;
1841 
1842 err_unlock:
1843 	mutex_unlock(&c->sb_lock);
1844 	up_write(&c->state_lock);
1845 err:
1846 	if (ca)
1847 		bch2_dev_free(ca);
1848 	bch2_free_super(&sb);
1849 	printbuf_exit(&label);
1850 	printbuf_exit(&errbuf);
1851 	bch_err_fn(c, ret);
1852 	return ret;
1853 err_late:
1854 	up_write(&c->state_lock);
1855 	ca = NULL;
1856 	goto err;
1857 }
1858 
1859 /* Hot add existing device to running filesystem: */
1860 int bch2_dev_online(struct bch_fs *c, const char *path)
1861 {
1862 	struct bch_opts opts = bch2_opts_empty();
1863 	struct bch_sb_handle sb = { NULL };
1864 	struct bch_dev *ca;
1865 	unsigned dev_idx;
1866 	int ret;
1867 
1868 	down_write(&c->state_lock);
1869 
1870 	ret = bch2_read_super(path, &opts, &sb);
1871 	if (ret) {
1872 		up_write(&c->state_lock);
1873 		return ret;
1874 	}
1875 
1876 	dev_idx = sb.sb->dev_idx;
1877 
1878 	ret = bch2_dev_in_fs(&c->disk_sb, &sb, &c->opts);
1879 	bch_err_msg(c, ret, "bringing %s online", path);
1880 	if (ret)
1881 		goto err;
1882 
1883 	ret = bch2_dev_attach_bdev(c, &sb);
1884 	if (ret)
1885 		goto err;
1886 
1887 	ca = bch_dev_locked(c, dev_idx);
1888 
1889 	ret = bch2_trans_mark_dev_sb(c, ca);
1890 	bch_err_msg(c, ret, "bringing %s online: error from bch2_trans_mark_dev_sb", path);
1891 	if (ret)
1892 		goto err;
1893 
1894 	if (ca->mi.state == BCH_MEMBER_STATE_rw)
1895 		__bch2_dev_read_write(c, ca);
1896 
1897 	if (!ca->mi.freespace_initialized) {
1898 		ret = bch2_dev_freespace_init(c, ca, 0, ca->mi.nbuckets);
1899 		bch_err_msg(ca, ret, "initializing free space");
1900 		if (ret)
1901 			goto err;
1902 	}
1903 
1904 	if (!ca->journal.nr) {
1905 		ret = bch2_dev_journal_alloc(ca);
1906 		bch_err_msg(ca, ret, "allocating journal");
1907 		if (ret)
1908 			goto err;
1909 	}
1910 
1911 	mutex_lock(&c->sb_lock);
1912 	bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx)->last_mount =
1913 		cpu_to_le64(ktime_get_real_seconds());
1914 	bch2_write_super(c);
1915 	mutex_unlock(&c->sb_lock);
1916 
1917 	up_write(&c->state_lock);
1918 	return 0;
1919 err:
1920 	up_write(&c->state_lock);
1921 	bch2_free_super(&sb);
1922 	return ret;
1923 }
1924 
1925 int bch2_dev_offline(struct bch_fs *c, struct bch_dev *ca, int flags)
1926 {
1927 	down_write(&c->state_lock);
1928 
1929 	if (!bch2_dev_is_online(ca)) {
1930 		bch_err(ca, "Already offline");
1931 		up_write(&c->state_lock);
1932 		return 0;
1933 	}
1934 
1935 	if (!bch2_dev_state_allowed(c, ca, BCH_MEMBER_STATE_failed, flags)) {
1936 		bch_err(ca, "Cannot offline required disk");
1937 		up_write(&c->state_lock);
1938 		return -BCH_ERR_device_state_not_allowed;
1939 	}
1940 
1941 	__bch2_dev_offline(c, ca);
1942 
1943 	up_write(&c->state_lock);
1944 	return 0;
1945 }
1946 
1947 int bch2_dev_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
1948 {
1949 	struct bch_member *m;
1950 	u64 old_nbuckets;
1951 	int ret = 0;
1952 
1953 	down_write(&c->state_lock);
1954 	old_nbuckets = ca->mi.nbuckets;
1955 
1956 	if (nbuckets < ca->mi.nbuckets) {
1957 		bch_err(ca, "Cannot shrink yet");
1958 		ret = -EINVAL;
1959 		goto err;
1960 	}
1961 
1962 	if (bch2_dev_is_online(ca) &&
1963 	    get_capacity(ca->disk_sb.bdev->bd_disk) <
1964 	    ca->mi.bucket_size * nbuckets) {
1965 		bch_err(ca, "New size larger than device");
1966 		ret = -BCH_ERR_device_size_too_small;
1967 		goto err;
1968 	}
1969 
1970 	ret = bch2_dev_buckets_resize(c, ca, nbuckets);
1971 	bch_err_msg(ca, ret, "resizing buckets");
1972 	if (ret)
1973 		goto err;
1974 
1975 	ret = bch2_trans_mark_dev_sb(c, ca);
1976 	if (ret)
1977 		goto err;
1978 
1979 	mutex_lock(&c->sb_lock);
1980 	m = bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx);
1981 	m->nbuckets = cpu_to_le64(nbuckets);
1982 
1983 	bch2_write_super(c);
1984 	mutex_unlock(&c->sb_lock);
1985 
1986 	if (ca->mi.freespace_initialized) {
1987 		ret = bch2_dev_freespace_init(c, ca, old_nbuckets, nbuckets);
1988 		if (ret)
1989 			goto err;
1990 
1991 		/*
1992 		 * XXX: this is all wrong transactionally - we'll be able to do
1993 		 * this correctly after the disk space accounting rewrite
1994 		 */
1995 		ca->usage_base->d[BCH_DATA_free].buckets += nbuckets - old_nbuckets;
1996 	}
1997 
1998 	bch2_recalc_capacity(c);
1999 err:
2000 	up_write(&c->state_lock);
2001 	return ret;
2002 }
2003 
2004 /* return with ref on ca->ref: */
2005 struct bch_dev *bch2_dev_lookup(struct bch_fs *c, const char *name)
2006 {
2007 	rcu_read_lock();
2008 	for_each_member_device_rcu(c, ca, NULL)
2009 		if (!strcmp(name, ca->name)) {
2010 			rcu_read_unlock();
2011 			return ca;
2012 		}
2013 	rcu_read_unlock();
2014 	return ERR_PTR(-BCH_ERR_ENOENT_dev_not_found);
2015 }
2016 
2017 /* Filesystem open: */
2018 
2019 static inline int sb_cmp(struct bch_sb *l, struct bch_sb *r)
2020 {
2021 	return  cmp_int(le64_to_cpu(l->seq), le64_to_cpu(r->seq)) ?:
2022 		cmp_int(le64_to_cpu(l->write_time), le64_to_cpu(r->write_time));
2023 }
2024 
2025 struct bch_fs *bch2_fs_open(char * const *devices, unsigned nr_devices,
2026 			    struct bch_opts opts)
2027 {
2028 	DARRAY(struct bch_sb_handle) sbs = { 0 };
2029 	struct bch_fs *c = NULL;
2030 	struct bch_sb_handle *best = NULL;
2031 	struct printbuf errbuf = PRINTBUF;
2032 	int ret = 0;
2033 
2034 	if (!try_module_get(THIS_MODULE))
2035 		return ERR_PTR(-ENODEV);
2036 
2037 	if (!nr_devices) {
2038 		ret = -EINVAL;
2039 		goto err;
2040 	}
2041 
2042 	ret = darray_make_room(&sbs, nr_devices);
2043 	if (ret)
2044 		goto err;
2045 
2046 	for (unsigned i = 0; i < nr_devices; i++) {
2047 		struct bch_sb_handle sb = { NULL };
2048 
2049 		ret = bch2_read_super(devices[i], &opts, &sb);
2050 		if (ret)
2051 			goto err;
2052 
2053 		BUG_ON(darray_push(&sbs, sb));
2054 	}
2055 
2056 	if (opts.nochanges && !opts.read_only) {
2057 		ret = -BCH_ERR_erofs_nochanges;
2058 		goto err_print;
2059 	}
2060 
2061 	darray_for_each(sbs, sb)
2062 		if (!best || sb_cmp(sb->sb, best->sb) > 0)
2063 			best = sb;
2064 
2065 	darray_for_each_reverse(sbs, sb) {
2066 		ret = bch2_dev_in_fs(best, sb, &opts);
2067 
2068 		if (ret == -BCH_ERR_device_has_been_removed ||
2069 		    ret == -BCH_ERR_device_splitbrain) {
2070 			bch2_free_super(sb);
2071 			darray_remove_item(&sbs, sb);
2072 			best -= best > sb;
2073 			ret = 0;
2074 			continue;
2075 		}
2076 
2077 		if (ret)
2078 			goto err_print;
2079 	}
2080 
2081 	c = bch2_fs_alloc(best->sb, opts);
2082 	ret = PTR_ERR_OR_ZERO(c);
2083 	if (ret)
2084 		goto err;
2085 
2086 	down_write(&c->state_lock);
2087 	darray_for_each(sbs, sb) {
2088 		ret = bch2_dev_attach_bdev(c, sb);
2089 		if (ret) {
2090 			up_write(&c->state_lock);
2091 			goto err;
2092 		}
2093 	}
2094 	up_write(&c->state_lock);
2095 
2096 	if (!bch2_fs_may_start(c)) {
2097 		ret = -BCH_ERR_insufficient_devices_to_start;
2098 		goto err_print;
2099 	}
2100 
2101 	if (!c->opts.nostart) {
2102 		ret = bch2_fs_start(c);
2103 		if (ret)
2104 			goto err;
2105 	}
2106 out:
2107 	darray_for_each(sbs, sb)
2108 		bch2_free_super(sb);
2109 	darray_exit(&sbs);
2110 	printbuf_exit(&errbuf);
2111 	module_put(THIS_MODULE);
2112 	return c;
2113 err_print:
2114 	pr_err("bch_fs_open err opening %s: %s",
2115 	       devices[0], bch2_err_str(ret));
2116 err:
2117 	if (!IS_ERR_OR_NULL(c))
2118 		bch2_fs_stop(c);
2119 	c = ERR_PTR(ret);
2120 	goto out;
2121 }
2122 
2123 /* Global interfaces/init */
2124 
2125 static void bcachefs_exit(void)
2126 {
2127 	bch2_debug_exit();
2128 	bch2_vfs_exit();
2129 	bch2_chardev_exit();
2130 	bch2_btree_key_cache_exit();
2131 	if (bcachefs_kset)
2132 		kset_unregister(bcachefs_kset);
2133 }
2134 
2135 static int __init bcachefs_init(void)
2136 {
2137 	bch2_bkey_pack_test();
2138 
2139 	if (!(bcachefs_kset = kset_create_and_add("bcachefs", NULL, fs_kobj)) ||
2140 	    bch2_btree_key_cache_init() ||
2141 	    bch2_chardev_init() ||
2142 	    bch2_vfs_init() ||
2143 	    bch2_debug_init())
2144 		goto err;
2145 
2146 	return 0;
2147 err:
2148 	bcachefs_exit();
2149 	return -ENOMEM;
2150 }
2151 
2152 #define BCH_DEBUG_PARAM(name, description)			\
2153 	bool bch2_##name;					\
2154 	module_param_named(name, bch2_##name, bool, 0644);	\
2155 	MODULE_PARM_DESC(name, description);
2156 BCH_DEBUG_PARAMS()
2157 #undef BCH_DEBUG_PARAM
2158 
2159 __maybe_unused
2160 static unsigned bch2_metadata_version = bcachefs_metadata_version_current;
2161 module_param_named(version, bch2_metadata_version, uint, 0400);
2162 
2163 module_exit(bcachefs_exit);
2164 module_init(bcachefs_init);
2165