xref: /linux/fs/bcachefs/super.c (revision dbcedec3a31119d7594baacc743300d127c99c56)
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_update_interior.h"
19 #include "btree_io.h"
20 #include "btree_write_buffer.h"
21 #include "buckets_waiting_for_journal.h"
22 #include "chardev.h"
23 #include "checksum.h"
24 #include "clock.h"
25 #include "compress.h"
26 #include "debug.h"
27 #include "disk_groups.h"
28 #include "ec.h"
29 #include "errcode.h"
30 #include "error.h"
31 #include "fs.h"
32 #include "fs-io.h"
33 #include "fs-io-buffered.h"
34 #include "fs-io-direct.h"
35 #include "fsck.h"
36 #include "inode.h"
37 #include "io_read.h"
38 #include "io_write.h"
39 #include "journal.h"
40 #include "journal_reclaim.h"
41 #include "journal_seq_blacklist.h"
42 #include "move.h"
43 #include "migrate.h"
44 #include "movinggc.h"
45 #include "nocow_locking.h"
46 #include "quota.h"
47 #include "rebalance.h"
48 #include "recovery.h"
49 #include "replicas.h"
50 #include "sb-clean.h"
51 #include "sb-counters.h"
52 #include "sb-errors.h"
53 #include "sb-members.h"
54 #include "snapshot.h"
55 #include "subvolume.h"
56 #include "super.h"
57 #include "super-io.h"
58 #include "sysfs.h"
59 #include "thread_with_file.h"
60 #include "trace.h"
61 
62 #include <linux/backing-dev.h>
63 #include <linux/blkdev.h>
64 #include <linux/debugfs.h>
65 #include <linux/device.h>
66 #include <linux/idr.h>
67 #include <linux/module.h>
68 #include <linux/percpu.h>
69 #include <linux/random.h>
70 #include <linux/sysfs.h>
71 #include <crypto/hash.h>
72 
73 MODULE_LICENSE("GPL");
74 MODULE_AUTHOR("Kent Overstreet <kent.overstreet@gmail.com>");
75 MODULE_DESCRIPTION("bcachefs filesystem");
76 MODULE_SOFTDEP("pre: crc32c");
77 MODULE_SOFTDEP("pre: crc64");
78 MODULE_SOFTDEP("pre: sha256");
79 MODULE_SOFTDEP("pre: chacha20");
80 MODULE_SOFTDEP("pre: poly1305");
81 MODULE_SOFTDEP("pre: xxhash");
82 
83 const char * const bch2_fs_flag_strs[] = {
84 #define x(n)		#n,
85 	BCH_FS_FLAGS()
86 #undef x
87 	NULL
88 };
89 
90 __printf(2, 0)
91 static void bch2_print_maybe_redirect(struct stdio_redirect *stdio, const char *fmt, va_list args)
92 {
93 #ifdef __KERNEL__
94 	if (unlikely(stdio)) {
95 		if (fmt[0] == KERN_SOH[0])
96 			fmt += 2;
97 
98 		bch2_stdio_redirect_vprintf(stdio, true, fmt, args);
99 		return;
100 	}
101 #endif
102 	vprintk(fmt, args);
103 }
104 
105 void bch2_print_opts(struct bch_opts *opts, const char *fmt, ...)
106 {
107 	struct stdio_redirect *stdio = (void *)(unsigned long)opts->stdio;
108 
109 	va_list args;
110 	va_start(args, fmt);
111 	bch2_print_maybe_redirect(stdio, fmt, args);
112 	va_end(args);
113 }
114 
115 void __bch2_print(struct bch_fs *c, const char *fmt, ...)
116 {
117 	struct stdio_redirect *stdio = bch2_fs_stdio_redirect(c);
118 
119 	va_list args;
120 	va_start(args, fmt);
121 	bch2_print_maybe_redirect(stdio, fmt, args);
122 	va_end(args);
123 }
124 
125 #define KTYPE(type)							\
126 static const struct attribute_group type ## _group = {			\
127 	.attrs = type ## _files						\
128 };									\
129 									\
130 static const struct attribute_group *type ## _groups[] = {		\
131 	&type ## _group,						\
132 	NULL								\
133 };									\
134 									\
135 static const struct kobj_type type ## _ktype = {			\
136 	.release	= type ## _release,				\
137 	.sysfs_ops	= &type ## _sysfs_ops,				\
138 	.default_groups = type ## _groups				\
139 }
140 
141 static void bch2_fs_release(struct kobject *);
142 static void bch2_dev_release(struct kobject *);
143 static void bch2_fs_counters_release(struct kobject *k)
144 {
145 }
146 
147 static void bch2_fs_internal_release(struct kobject *k)
148 {
149 }
150 
151 static void bch2_fs_opts_dir_release(struct kobject *k)
152 {
153 }
154 
155 static void bch2_fs_time_stats_release(struct kobject *k)
156 {
157 }
158 
159 KTYPE(bch2_fs);
160 KTYPE(bch2_fs_counters);
161 KTYPE(bch2_fs_internal);
162 KTYPE(bch2_fs_opts_dir);
163 KTYPE(bch2_fs_time_stats);
164 KTYPE(bch2_dev);
165 
166 static struct kset *bcachefs_kset;
167 static LIST_HEAD(bch_fs_list);
168 static DEFINE_MUTEX(bch_fs_list_lock);
169 
170 DECLARE_WAIT_QUEUE_HEAD(bch2_read_only_wait);
171 
172 static void bch2_dev_free(struct bch_dev *);
173 static int bch2_dev_alloc(struct bch_fs *, unsigned);
174 static int bch2_dev_sysfs_online(struct bch_fs *, struct bch_dev *);
175 static void __bch2_dev_read_only(struct bch_fs *, struct bch_dev *);
176 
177 struct bch_fs *bch2_dev_to_fs(dev_t dev)
178 {
179 	struct bch_fs *c;
180 
181 	mutex_lock(&bch_fs_list_lock);
182 	rcu_read_lock();
183 
184 	list_for_each_entry(c, &bch_fs_list, list)
185 		for_each_member_device_rcu(c, ca, NULL)
186 			if (ca->disk_sb.bdev && ca->disk_sb.bdev->bd_dev == dev) {
187 				closure_get(&c->cl);
188 				goto found;
189 			}
190 	c = NULL;
191 found:
192 	rcu_read_unlock();
193 	mutex_unlock(&bch_fs_list_lock);
194 
195 	return c;
196 }
197 
198 static struct bch_fs *__bch2_uuid_to_fs(__uuid_t uuid)
199 {
200 	struct bch_fs *c;
201 
202 	lockdep_assert_held(&bch_fs_list_lock);
203 
204 	list_for_each_entry(c, &bch_fs_list, list)
205 		if (!memcmp(&c->disk_sb.sb->uuid, &uuid, sizeof(uuid)))
206 			return c;
207 
208 	return NULL;
209 }
210 
211 struct bch_fs *bch2_uuid_to_fs(__uuid_t uuid)
212 {
213 	struct bch_fs *c;
214 
215 	mutex_lock(&bch_fs_list_lock);
216 	c = __bch2_uuid_to_fs(uuid);
217 	if (c)
218 		closure_get(&c->cl);
219 	mutex_unlock(&bch_fs_list_lock);
220 
221 	return c;
222 }
223 
224 static void bch2_dev_usage_journal_reserve(struct bch_fs *c)
225 {
226 	unsigned nr = 0, u64s =
227 		((sizeof(struct jset_entry_dev_usage) +
228 		  sizeof(struct jset_entry_dev_usage_type) * BCH_DATA_NR)) /
229 		sizeof(u64);
230 
231 	rcu_read_lock();
232 	for_each_member_device_rcu(c, ca, NULL)
233 		nr++;
234 	rcu_read_unlock();
235 
236 	bch2_journal_entry_res_resize(&c->journal,
237 			&c->dev_usage_journal_res, u64s * nr);
238 }
239 
240 /* Filesystem RO/RW: */
241 
242 /*
243  * For startup/shutdown of RW stuff, the dependencies are:
244  *
245  * - foreground writes depend on copygc and rebalance (to free up space)
246  *
247  * - copygc and rebalance depend on mark and sweep gc (they actually probably
248  *   don't because they either reserve ahead of time or don't block if
249  *   allocations fail, but allocations can require mark and sweep gc to run
250  *   because of generation number wraparound)
251  *
252  * - all of the above depends on the allocator threads
253  *
254  * - allocator depends on the journal (when it rewrites prios and gens)
255  */
256 
257 static void __bch2_fs_read_only(struct bch_fs *c)
258 {
259 	unsigned clean_passes = 0;
260 	u64 seq = 0;
261 
262 	bch2_fs_ec_stop(c);
263 	bch2_open_buckets_stop(c, NULL, true);
264 	bch2_rebalance_stop(c);
265 	bch2_copygc_stop(c);
266 	bch2_gc_thread_stop(c);
267 	bch2_fs_ec_flush(c);
268 
269 	bch_verbose(c, "flushing journal and stopping allocators, journal seq %llu",
270 		    journal_cur_seq(&c->journal));
271 
272 	do {
273 		clean_passes++;
274 
275 		if (bch2_btree_interior_updates_flush(c) ||
276 		    bch2_journal_flush_all_pins(&c->journal) ||
277 		    bch2_btree_flush_all_writes(c) ||
278 		    seq != atomic64_read(&c->journal.seq)) {
279 			seq = atomic64_read(&c->journal.seq);
280 			clean_passes = 0;
281 		}
282 	} while (clean_passes < 2);
283 
284 	bch_verbose(c, "flushing journal and stopping allocators complete, journal seq %llu",
285 		    journal_cur_seq(&c->journal));
286 
287 	if (test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags) &&
288 	    !test_bit(BCH_FS_emergency_ro, &c->flags))
289 		set_bit(BCH_FS_clean_shutdown, &c->flags);
290 	bch2_fs_journal_stop(&c->journal);
291 
292 	/*
293 	 * After stopping journal:
294 	 */
295 	for_each_member_device(c, ca)
296 		bch2_dev_allocator_remove(c, ca);
297 }
298 
299 #ifndef BCH_WRITE_REF_DEBUG
300 static void bch2_writes_disabled(struct percpu_ref *writes)
301 {
302 	struct bch_fs *c = container_of(writes, struct bch_fs, writes);
303 
304 	set_bit(BCH_FS_write_disable_complete, &c->flags);
305 	wake_up(&bch2_read_only_wait);
306 }
307 #endif
308 
309 void bch2_fs_read_only(struct bch_fs *c)
310 {
311 	if (!test_bit(BCH_FS_rw, &c->flags)) {
312 		bch2_journal_reclaim_stop(&c->journal);
313 		return;
314 	}
315 
316 	BUG_ON(test_bit(BCH_FS_write_disable_complete, &c->flags));
317 
318 	bch_verbose(c, "going read-only");
319 
320 	/*
321 	 * Block new foreground-end write operations from starting - any new
322 	 * writes will return -EROFS:
323 	 */
324 	set_bit(BCH_FS_going_ro, &c->flags);
325 #ifndef BCH_WRITE_REF_DEBUG
326 	percpu_ref_kill(&c->writes);
327 #else
328 	for (unsigned i = 0; i < BCH_WRITE_REF_NR; i++)
329 		bch2_write_ref_put(c, i);
330 #endif
331 
332 	/*
333 	 * If we're not doing an emergency shutdown, we want to wait on
334 	 * outstanding writes to complete so they don't see spurious errors due
335 	 * to shutting down the allocator:
336 	 *
337 	 * If we are doing an emergency shutdown outstanding writes may
338 	 * hang until we shutdown the allocator so we don't want to wait
339 	 * on outstanding writes before shutting everything down - but
340 	 * we do need to wait on them before returning and signalling
341 	 * that going RO is complete:
342 	 */
343 	wait_event(bch2_read_only_wait,
344 		   test_bit(BCH_FS_write_disable_complete, &c->flags) ||
345 		   test_bit(BCH_FS_emergency_ro, &c->flags));
346 
347 	bool writes_disabled = test_bit(BCH_FS_write_disable_complete, &c->flags);
348 	if (writes_disabled)
349 		bch_verbose(c, "finished waiting for writes to stop");
350 
351 	__bch2_fs_read_only(c);
352 
353 	wait_event(bch2_read_only_wait,
354 		   test_bit(BCH_FS_write_disable_complete, &c->flags));
355 
356 	if (!writes_disabled)
357 		bch_verbose(c, "finished waiting for writes to stop");
358 
359 	clear_bit(BCH_FS_write_disable_complete, &c->flags);
360 	clear_bit(BCH_FS_going_ro, &c->flags);
361 	clear_bit(BCH_FS_rw, &c->flags);
362 
363 	if (!bch2_journal_error(&c->journal) &&
364 	    !test_bit(BCH_FS_error, &c->flags) &&
365 	    !test_bit(BCH_FS_emergency_ro, &c->flags) &&
366 	    test_bit(BCH_FS_started, &c->flags) &&
367 	    test_bit(BCH_FS_clean_shutdown, &c->flags) &&
368 	    !c->opts.norecovery) {
369 		BUG_ON(c->journal.last_empty_seq != journal_cur_seq(&c->journal));
370 		BUG_ON(atomic_read(&c->btree_cache.dirty));
371 		BUG_ON(atomic_long_read(&c->btree_key_cache.nr_dirty));
372 		BUG_ON(c->btree_write_buffer.inc.keys.nr);
373 		BUG_ON(c->btree_write_buffer.flushing.keys.nr);
374 
375 		bch_verbose(c, "marking filesystem clean");
376 		bch2_fs_mark_clean(c);
377 	} else {
378 		bch_verbose(c, "done going read-only, filesystem not clean");
379 	}
380 }
381 
382 static void bch2_fs_read_only_work(struct work_struct *work)
383 {
384 	struct bch_fs *c =
385 		container_of(work, struct bch_fs, read_only_work);
386 
387 	down_write(&c->state_lock);
388 	bch2_fs_read_only(c);
389 	up_write(&c->state_lock);
390 }
391 
392 static void bch2_fs_read_only_async(struct bch_fs *c)
393 {
394 	queue_work(system_long_wq, &c->read_only_work);
395 }
396 
397 bool bch2_fs_emergency_read_only(struct bch_fs *c)
398 {
399 	bool ret = !test_and_set_bit(BCH_FS_emergency_ro, &c->flags);
400 
401 	bch2_journal_halt(&c->journal);
402 	bch2_fs_read_only_async(c);
403 
404 	wake_up(&bch2_read_only_wait);
405 	return ret;
406 }
407 
408 static int bch2_fs_read_write_late(struct bch_fs *c)
409 {
410 	int ret;
411 
412 	/*
413 	 * Data move operations can't run until after check_snapshots has
414 	 * completed, and bch2_snapshot_is_ancestor() is available.
415 	 *
416 	 * Ideally we'd start copygc/rebalance earlier instead of waiting for
417 	 * all of recovery/fsck to complete:
418 	 */
419 	ret = bch2_copygc_start(c);
420 	if (ret) {
421 		bch_err(c, "error starting copygc thread");
422 		return ret;
423 	}
424 
425 	ret = bch2_rebalance_start(c);
426 	if (ret) {
427 		bch_err(c, "error starting rebalance thread");
428 		return ret;
429 	}
430 
431 	return 0;
432 }
433 
434 static int __bch2_fs_read_write(struct bch_fs *c, bool early)
435 {
436 	int ret;
437 
438 	if (test_bit(BCH_FS_initial_gc_unfixed, &c->flags)) {
439 		bch_err(c, "cannot go rw, unfixed btree errors");
440 		return -BCH_ERR_erofs_unfixed_errors;
441 	}
442 
443 	if (test_bit(BCH_FS_rw, &c->flags))
444 		return 0;
445 
446 	bch_info(c, "going read-write");
447 
448 	ret = bch2_sb_members_v2_init(c);
449 	if (ret)
450 		goto err;
451 
452 	ret = bch2_fs_mark_dirty(c);
453 	if (ret)
454 		goto err;
455 
456 	clear_bit(BCH_FS_clean_shutdown, &c->flags);
457 
458 	/*
459 	 * First journal write must be a flush write: after a clean shutdown we
460 	 * don't read the journal, so the first journal write may end up
461 	 * overwriting whatever was there previously, and there must always be
462 	 * at least one non-flush write in the journal or recovery will fail:
463 	 */
464 	set_bit(JOURNAL_NEED_FLUSH_WRITE, &c->journal.flags);
465 
466 	for_each_rw_member(c, ca)
467 		bch2_dev_allocator_add(c, ca);
468 	bch2_recalc_capacity(c);
469 
470 	set_bit(BCH_FS_rw, &c->flags);
471 	set_bit(BCH_FS_was_rw, &c->flags);
472 
473 #ifndef BCH_WRITE_REF_DEBUG
474 	percpu_ref_reinit(&c->writes);
475 #else
476 	for (unsigned i = 0; i < BCH_WRITE_REF_NR; i++) {
477 		BUG_ON(atomic_long_read(&c->writes[i]));
478 		atomic_long_inc(&c->writes[i]);
479 	}
480 #endif
481 
482 	ret = bch2_gc_thread_start(c);
483 	if (ret) {
484 		bch_err(c, "error starting gc thread");
485 		return ret;
486 	}
487 
488 	ret = bch2_journal_reclaim_start(&c->journal);
489 	if (ret)
490 		goto err;
491 
492 	if (!early) {
493 		ret = bch2_fs_read_write_late(c);
494 		if (ret)
495 			goto err;
496 	}
497 
498 	bch2_do_discards(c);
499 	bch2_do_invalidates(c);
500 	bch2_do_stripe_deletes(c);
501 	bch2_do_pending_node_rewrites(c);
502 	return 0;
503 err:
504 	if (test_bit(BCH_FS_rw, &c->flags))
505 		bch2_fs_read_only(c);
506 	else
507 		__bch2_fs_read_only(c);
508 	return ret;
509 }
510 
511 int bch2_fs_read_write(struct bch_fs *c)
512 {
513 	if (c->opts.norecovery)
514 		return -BCH_ERR_erofs_norecovery;
515 
516 	if (c->opts.nochanges)
517 		return -BCH_ERR_erofs_nochanges;
518 
519 	return __bch2_fs_read_write(c, false);
520 }
521 
522 int bch2_fs_read_write_early(struct bch_fs *c)
523 {
524 	lockdep_assert_held(&c->state_lock);
525 
526 	return __bch2_fs_read_write(c, true);
527 }
528 
529 /* Filesystem startup/shutdown: */
530 
531 static void __bch2_fs_free(struct bch_fs *c)
532 {
533 	unsigned i;
534 
535 	for (i = 0; i < BCH_TIME_STAT_NR; i++)
536 		bch2_time_stats_exit(&c->times[i]);
537 
538 	bch2_free_pending_node_rewrites(c);
539 	bch2_fs_sb_errors_exit(c);
540 	bch2_fs_counters_exit(c);
541 	bch2_fs_snapshots_exit(c);
542 	bch2_fs_quota_exit(c);
543 	bch2_fs_fs_io_direct_exit(c);
544 	bch2_fs_fs_io_buffered_exit(c);
545 	bch2_fs_fsio_exit(c);
546 	bch2_fs_ec_exit(c);
547 	bch2_fs_encryption_exit(c);
548 	bch2_fs_nocow_locking_exit(c);
549 	bch2_fs_io_write_exit(c);
550 	bch2_fs_io_read_exit(c);
551 	bch2_fs_buckets_waiting_for_journal_exit(c);
552 	bch2_fs_btree_interior_update_exit(c);
553 	bch2_fs_btree_iter_exit(c);
554 	bch2_fs_btree_key_cache_exit(&c->btree_key_cache);
555 	bch2_fs_btree_cache_exit(c);
556 	bch2_fs_replicas_exit(c);
557 	bch2_fs_journal_exit(&c->journal);
558 	bch2_io_clock_exit(&c->io_clock[WRITE]);
559 	bch2_io_clock_exit(&c->io_clock[READ]);
560 	bch2_fs_compress_exit(c);
561 	bch2_journal_keys_put_initial(c);
562 	BUG_ON(atomic_read(&c->journal_keys.ref));
563 	bch2_fs_btree_write_buffer_exit(c);
564 	percpu_free_rwsem(&c->mark_lock);
565 	free_percpu(c->online_reserved);
566 
567 	darray_exit(&c->btree_roots_extra);
568 	free_percpu(c->pcpu);
569 	mempool_exit(&c->large_bkey_pool);
570 	mempool_exit(&c->btree_bounce_pool);
571 	bioset_exit(&c->btree_bio);
572 	mempool_exit(&c->fill_iter);
573 #ifndef BCH_WRITE_REF_DEBUG
574 	percpu_ref_exit(&c->writes);
575 #endif
576 	kfree(rcu_dereference_protected(c->disk_groups, 1));
577 	kfree(c->journal_seq_blacklist_table);
578 	kfree(c->unused_inode_hints);
579 
580 	if (c->write_ref_wq)
581 		destroy_workqueue(c->write_ref_wq);
582 	if (c->io_complete_wq)
583 		destroy_workqueue(c->io_complete_wq);
584 	if (c->copygc_wq)
585 		destroy_workqueue(c->copygc_wq);
586 	if (c->btree_io_complete_wq)
587 		destroy_workqueue(c->btree_io_complete_wq);
588 	if (c->btree_update_wq)
589 		destroy_workqueue(c->btree_update_wq);
590 
591 	bch2_free_super(&c->disk_sb);
592 	kvfree(c);
593 	module_put(THIS_MODULE);
594 }
595 
596 static void bch2_fs_release(struct kobject *kobj)
597 {
598 	struct bch_fs *c = container_of(kobj, struct bch_fs, kobj);
599 
600 	__bch2_fs_free(c);
601 }
602 
603 void __bch2_fs_stop(struct bch_fs *c)
604 {
605 	bch_verbose(c, "shutting down");
606 
607 	set_bit(BCH_FS_stopping, &c->flags);
608 
609 	cancel_work_sync(&c->journal_seq_blacklist_gc_work);
610 
611 	down_write(&c->state_lock);
612 	bch2_fs_read_only(c);
613 	up_write(&c->state_lock);
614 
615 	for_each_member_device(c, ca)
616 		if (ca->kobj.state_in_sysfs &&
617 		    ca->disk_sb.bdev)
618 			sysfs_remove_link(bdev_kobj(ca->disk_sb.bdev), "bcachefs");
619 
620 	if (c->kobj.state_in_sysfs)
621 		kobject_del(&c->kobj);
622 
623 	bch2_fs_debug_exit(c);
624 	bch2_fs_chardev_exit(c);
625 
626 	bch2_ro_ref_put(c);
627 	wait_event(c->ro_ref_wait, !refcount_read(&c->ro_ref));
628 
629 	kobject_put(&c->counters_kobj);
630 	kobject_put(&c->time_stats);
631 	kobject_put(&c->opts_dir);
632 	kobject_put(&c->internal);
633 
634 	/* btree prefetch might have kicked off reads in the background: */
635 	bch2_btree_flush_all_reads(c);
636 
637 	for_each_member_device(c, ca)
638 		cancel_work_sync(&ca->io_error_work);
639 
640 	cancel_work_sync(&c->read_only_work);
641 }
642 
643 void bch2_fs_free(struct bch_fs *c)
644 {
645 	unsigned i;
646 
647 	mutex_lock(&bch_fs_list_lock);
648 	list_del(&c->list);
649 	mutex_unlock(&bch_fs_list_lock);
650 
651 	closure_sync(&c->cl);
652 	closure_debug_destroy(&c->cl);
653 
654 	for (i = 0; i < c->sb.nr_devices; i++) {
655 		struct bch_dev *ca = rcu_dereference_protected(c->devs[i], true);
656 
657 		if (ca) {
658 			bch2_free_super(&ca->disk_sb);
659 			bch2_dev_free(ca);
660 		}
661 	}
662 
663 	bch_verbose(c, "shutdown complete");
664 
665 	kobject_put(&c->kobj);
666 }
667 
668 void bch2_fs_stop(struct bch_fs *c)
669 {
670 	__bch2_fs_stop(c);
671 	bch2_fs_free(c);
672 }
673 
674 static int bch2_fs_online(struct bch_fs *c)
675 {
676 	int ret = 0;
677 
678 	lockdep_assert_held(&bch_fs_list_lock);
679 
680 	if (__bch2_uuid_to_fs(c->sb.uuid)) {
681 		bch_err(c, "filesystem UUID already open");
682 		return -EINVAL;
683 	}
684 
685 	ret = bch2_fs_chardev_init(c);
686 	if (ret) {
687 		bch_err(c, "error creating character device");
688 		return ret;
689 	}
690 
691 	bch2_fs_debug_init(c);
692 
693 	ret = kobject_add(&c->kobj, NULL, "%pU", c->sb.user_uuid.b) ?:
694 	    kobject_add(&c->internal, &c->kobj, "internal") ?:
695 	    kobject_add(&c->opts_dir, &c->kobj, "options") ?:
696 #ifndef CONFIG_BCACHEFS_NO_LATENCY_ACCT
697 	    kobject_add(&c->time_stats, &c->kobj, "time_stats") ?:
698 #endif
699 	    kobject_add(&c->counters_kobj, &c->kobj, "counters") ?:
700 	    bch2_opts_create_sysfs_files(&c->opts_dir);
701 	if (ret) {
702 		bch_err(c, "error creating sysfs objects");
703 		return ret;
704 	}
705 
706 	down_write(&c->state_lock);
707 
708 	for_each_member_device(c, ca) {
709 		ret = bch2_dev_sysfs_online(c, ca);
710 		if (ret) {
711 			bch_err(c, "error creating sysfs objects");
712 			percpu_ref_put(&ca->ref);
713 			goto err;
714 		}
715 	}
716 
717 	BUG_ON(!list_empty(&c->list));
718 	list_add(&c->list, &bch_fs_list);
719 err:
720 	up_write(&c->state_lock);
721 	return ret;
722 }
723 
724 static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
725 {
726 	struct bch_fs *c;
727 	struct printbuf name = PRINTBUF;
728 	unsigned i, iter_size;
729 	int ret = 0;
730 
731 	c = kvmalloc(sizeof(struct bch_fs), GFP_KERNEL|__GFP_ZERO);
732 	if (!c) {
733 		c = ERR_PTR(-BCH_ERR_ENOMEM_fs_alloc);
734 		goto out;
735 	}
736 
737 	c->stdio = (void *)(unsigned long) opts.stdio;
738 
739 	__module_get(THIS_MODULE);
740 
741 	closure_init(&c->cl, NULL);
742 
743 	c->kobj.kset = bcachefs_kset;
744 	kobject_init(&c->kobj, &bch2_fs_ktype);
745 	kobject_init(&c->internal, &bch2_fs_internal_ktype);
746 	kobject_init(&c->opts_dir, &bch2_fs_opts_dir_ktype);
747 	kobject_init(&c->time_stats, &bch2_fs_time_stats_ktype);
748 	kobject_init(&c->counters_kobj, &bch2_fs_counters_ktype);
749 
750 	c->minor		= -1;
751 	c->disk_sb.fs_sb	= true;
752 
753 	init_rwsem(&c->state_lock);
754 	mutex_init(&c->sb_lock);
755 	mutex_init(&c->replicas_gc_lock);
756 	mutex_init(&c->btree_root_lock);
757 	INIT_WORK(&c->read_only_work, bch2_fs_read_only_work);
758 
759 	refcount_set(&c->ro_ref, 1);
760 	init_waitqueue_head(&c->ro_ref_wait);
761 	sema_init(&c->online_fsck_mutex, 1);
762 
763 	init_rwsem(&c->gc_lock);
764 	mutex_init(&c->gc_gens_lock);
765 	atomic_set(&c->journal_keys.ref, 1);
766 	c->journal_keys.initial_ref_held = true;
767 
768 	for (i = 0; i < BCH_TIME_STAT_NR; i++)
769 		bch2_time_stats_init(&c->times[i]);
770 
771 	bch2_fs_copygc_init(c);
772 	bch2_fs_btree_key_cache_init_early(&c->btree_key_cache);
773 	bch2_fs_btree_iter_init_early(c);
774 	bch2_fs_btree_interior_update_init_early(c);
775 	bch2_fs_allocator_background_init(c);
776 	bch2_fs_allocator_foreground_init(c);
777 	bch2_fs_rebalance_init(c);
778 	bch2_fs_quota_init(c);
779 	bch2_fs_ec_init_early(c);
780 	bch2_fs_move_init(c);
781 	bch2_fs_sb_errors_init_early(c);
782 
783 	INIT_LIST_HEAD(&c->list);
784 
785 	mutex_init(&c->usage_scratch_lock);
786 
787 	mutex_init(&c->bio_bounce_pages_lock);
788 	mutex_init(&c->snapshot_table_lock);
789 	init_rwsem(&c->snapshot_create_lock);
790 
791 	spin_lock_init(&c->btree_write_error_lock);
792 
793 	INIT_WORK(&c->journal_seq_blacklist_gc_work,
794 		  bch2_blacklist_entries_gc);
795 
796 	INIT_LIST_HEAD(&c->journal_iters);
797 
798 	INIT_LIST_HEAD(&c->fsck_error_msgs);
799 	mutex_init(&c->fsck_error_msgs_lock);
800 
801 	seqcount_init(&c->gc_pos_lock);
802 
803 	seqcount_init(&c->usage_lock);
804 
805 	sema_init(&c->io_in_flight, 128);
806 
807 	INIT_LIST_HEAD(&c->vfs_inodes_list);
808 	mutex_init(&c->vfs_inodes_lock);
809 
810 	c->copy_gc_enabled		= 1;
811 	c->rebalance.enabled		= 1;
812 	c->promote_whole_extents	= true;
813 
814 	c->journal.flush_write_time	= &c->times[BCH_TIME_journal_flush_write];
815 	c->journal.noflush_write_time	= &c->times[BCH_TIME_journal_noflush_write];
816 	c->journal.flush_seq_time	= &c->times[BCH_TIME_journal_flush_seq];
817 
818 	bch2_fs_btree_cache_init_early(&c->btree_cache);
819 
820 	mutex_init(&c->sectors_available_lock);
821 
822 	ret = percpu_init_rwsem(&c->mark_lock);
823 	if (ret)
824 		goto err;
825 
826 	mutex_lock(&c->sb_lock);
827 	ret = bch2_sb_to_fs(c, sb);
828 	mutex_unlock(&c->sb_lock);
829 
830 	if (ret)
831 		goto err;
832 
833 	pr_uuid(&name, c->sb.user_uuid.b);
834 	ret = name.allocation_failure ? -BCH_ERR_ENOMEM_fs_name_alloc : 0;
835 	if (ret)
836 		goto err;
837 
838 	strscpy(c->name, name.buf, sizeof(c->name));
839 	printbuf_exit(&name);
840 
841 	/* Compat: */
842 	if (le16_to_cpu(sb->version) <= bcachefs_metadata_version_inode_v2 &&
843 	    !BCH_SB_JOURNAL_FLUSH_DELAY(sb))
844 		SET_BCH_SB_JOURNAL_FLUSH_DELAY(sb, 1000);
845 
846 	if (le16_to_cpu(sb->version) <= bcachefs_metadata_version_inode_v2 &&
847 	    !BCH_SB_JOURNAL_RECLAIM_DELAY(sb))
848 		SET_BCH_SB_JOURNAL_RECLAIM_DELAY(sb, 100);
849 
850 	c->opts = bch2_opts_default;
851 	ret = bch2_opts_from_sb(&c->opts, sb);
852 	if (ret)
853 		goto err;
854 
855 	bch2_opts_apply(&c->opts, opts);
856 
857 	c->btree_key_cache_btrees |= 1U << BTREE_ID_alloc;
858 	if (c->opts.inodes_use_key_cache)
859 		c->btree_key_cache_btrees |= 1U << BTREE_ID_inodes;
860 	c->btree_key_cache_btrees |= 1U << BTREE_ID_logged_ops;
861 
862 	c->block_bits		= ilog2(block_sectors(c));
863 	c->btree_foreground_merge_threshold = BTREE_FOREGROUND_MERGE_THRESHOLD(c);
864 
865 	if (bch2_fs_init_fault("fs_alloc")) {
866 		bch_err(c, "fs_alloc fault injected");
867 		ret = -EFAULT;
868 		goto err;
869 	}
870 
871 	iter_size = sizeof(struct sort_iter) +
872 		(btree_blocks(c) + 1) * 2 *
873 		sizeof(struct sort_iter_set);
874 
875 	c->inode_shard_bits = ilog2(roundup_pow_of_two(num_possible_cpus()));
876 
877 	if (!(c->btree_update_wq = alloc_workqueue("bcachefs",
878 				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM|WQ_UNBOUND, 512)) ||
879 	    !(c->btree_io_complete_wq = alloc_workqueue("bcachefs_btree_io",
880 				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM, 1)) ||
881 	    !(c->copygc_wq = alloc_workqueue("bcachefs_copygc",
882 				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE, 1)) ||
883 	    !(c->io_complete_wq = alloc_workqueue("bcachefs_io",
884 				WQ_HIGHPRI|WQ_FREEZABLE|WQ_MEM_RECLAIM, 512)) ||
885 	    !(c->write_ref_wq = alloc_workqueue("bcachefs_write_ref",
886 				WQ_FREEZABLE, 0)) ||
887 #ifndef BCH_WRITE_REF_DEBUG
888 	    percpu_ref_init(&c->writes, bch2_writes_disabled,
889 			    PERCPU_REF_INIT_DEAD, GFP_KERNEL) ||
890 #endif
891 	    mempool_init_kmalloc_pool(&c->fill_iter, 1, iter_size) ||
892 	    bioset_init(&c->btree_bio, 1,
893 			max(offsetof(struct btree_read_bio, bio),
894 			    offsetof(struct btree_write_bio, wbio.bio)),
895 			BIOSET_NEED_BVECS) ||
896 	    !(c->pcpu = alloc_percpu(struct bch_fs_pcpu)) ||
897 	    !(c->online_reserved = alloc_percpu(u64)) ||
898 	    mempool_init_kvmalloc_pool(&c->btree_bounce_pool, 1,
899 				       c->opts.btree_node_size) ||
900 	    mempool_init_kmalloc_pool(&c->large_bkey_pool, 1, 2048) ||
901 	    !(c->unused_inode_hints = kcalloc(1U << c->inode_shard_bits,
902 					      sizeof(u64), GFP_KERNEL))) {
903 		ret = -BCH_ERR_ENOMEM_fs_other_alloc;
904 		goto err;
905 	}
906 
907 	ret = bch2_fs_counters_init(c) ?:
908 	    bch2_fs_sb_errors_init(c) ?:
909 	    bch2_io_clock_init(&c->io_clock[READ]) ?:
910 	    bch2_io_clock_init(&c->io_clock[WRITE]) ?:
911 	    bch2_fs_journal_init(&c->journal) ?:
912 	    bch2_fs_replicas_init(c) ?:
913 	    bch2_fs_btree_cache_init(c) ?:
914 	    bch2_fs_btree_key_cache_init(&c->btree_key_cache) ?:
915 	    bch2_fs_btree_iter_init(c) ?:
916 	    bch2_fs_btree_interior_update_init(c) ?:
917 	    bch2_fs_buckets_waiting_for_journal_init(c) ?:
918 	    bch2_fs_btree_write_buffer_init(c) ?:
919 	    bch2_fs_subvolumes_init(c) ?:
920 	    bch2_fs_io_read_init(c) ?:
921 	    bch2_fs_io_write_init(c) ?:
922 	    bch2_fs_nocow_locking_init(c) ?:
923 	    bch2_fs_encryption_init(c) ?:
924 	    bch2_fs_compress_init(c) ?:
925 	    bch2_fs_ec_init(c) ?:
926 	    bch2_fs_fsio_init(c) ?:
927 	    bch2_fs_fs_io_buffered_init(c) ?:
928 	    bch2_fs_fs_io_direct_init(c);
929 	if (ret)
930 		goto err;
931 
932 	for (i = 0; i < c->sb.nr_devices; i++)
933 		if (bch2_dev_exists(c->disk_sb.sb, i) &&
934 		    bch2_dev_alloc(c, i)) {
935 			ret = -EEXIST;
936 			goto err;
937 		}
938 
939 	bch2_journal_entry_res_resize(&c->journal,
940 			&c->btree_root_journal_res,
941 			BTREE_ID_NR * (JSET_KEYS_U64s + BKEY_BTREE_PTR_U64s_MAX));
942 	bch2_dev_usage_journal_reserve(c);
943 	bch2_journal_entry_res_resize(&c->journal,
944 			&c->clock_journal_res,
945 			(sizeof(struct jset_entry_clock) / sizeof(u64)) * 2);
946 
947 	mutex_lock(&bch_fs_list_lock);
948 	ret = bch2_fs_online(c);
949 	mutex_unlock(&bch_fs_list_lock);
950 
951 	if (ret)
952 		goto err;
953 out:
954 	return c;
955 err:
956 	bch2_fs_free(c);
957 	c = ERR_PTR(ret);
958 	goto out;
959 }
960 
961 noinline_for_stack
962 static void print_mount_opts(struct bch_fs *c)
963 {
964 	enum bch_opt_id i;
965 	struct printbuf p = PRINTBUF;
966 	bool first = true;
967 
968 	prt_str(&p, "mounting version ");
969 	bch2_version_to_text(&p, c->sb.version);
970 
971 	if (c->opts.read_only) {
972 		prt_str(&p, " opts=");
973 		first = false;
974 		prt_printf(&p, "ro");
975 	}
976 
977 	for (i = 0; i < bch2_opts_nr; i++) {
978 		const struct bch_option *opt = &bch2_opt_table[i];
979 		u64 v = bch2_opt_get_by_id(&c->opts, i);
980 
981 		if (!(opt->flags & OPT_MOUNT))
982 			continue;
983 
984 		if (v == bch2_opt_get_by_id(&bch2_opts_default, i))
985 			continue;
986 
987 		prt_str(&p, first ? " opts=" : ",");
988 		first = false;
989 		bch2_opt_to_text(&p, c, c->disk_sb.sb, opt, v, OPT_SHOW_MOUNT_STYLE);
990 	}
991 
992 	bch_info(c, "%s", p.buf);
993 	printbuf_exit(&p);
994 }
995 
996 int bch2_fs_start(struct bch_fs *c)
997 {
998 	time64_t now = ktime_get_real_seconds();
999 	int ret;
1000 
1001 	print_mount_opts(c);
1002 
1003 	down_write(&c->state_lock);
1004 
1005 	BUG_ON(test_bit(BCH_FS_started, &c->flags));
1006 
1007 	mutex_lock(&c->sb_lock);
1008 
1009 	ret = bch2_sb_members_v2_init(c);
1010 	if (ret) {
1011 		mutex_unlock(&c->sb_lock);
1012 		goto err;
1013 	}
1014 
1015 	for_each_online_member(c, ca)
1016 		bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx)->last_mount = cpu_to_le64(now);
1017 
1018 	mutex_unlock(&c->sb_lock);
1019 
1020 	for_each_rw_member(c, ca)
1021 		bch2_dev_allocator_add(c, ca);
1022 	bch2_recalc_capacity(c);
1023 
1024 	ret = BCH_SB_INITIALIZED(c->disk_sb.sb)
1025 		? bch2_fs_recovery(c)
1026 		: bch2_fs_initialize(c);
1027 	if (ret)
1028 		goto err;
1029 
1030 	ret = bch2_opts_check_may_set(c);
1031 	if (ret)
1032 		goto err;
1033 
1034 	if (bch2_fs_init_fault("fs_start")) {
1035 		bch_err(c, "fs_start fault injected");
1036 		ret = -EINVAL;
1037 		goto err;
1038 	}
1039 
1040 	set_bit(BCH_FS_started, &c->flags);
1041 
1042 	if (c->opts.read_only) {
1043 		bch2_fs_read_only(c);
1044 	} else {
1045 		ret = !test_bit(BCH_FS_rw, &c->flags)
1046 			? bch2_fs_read_write(c)
1047 			: bch2_fs_read_write_late(c);
1048 		if (ret)
1049 			goto err;
1050 	}
1051 
1052 	ret = 0;
1053 err:
1054 	if (ret)
1055 		bch_err_msg(c, ret, "starting filesystem");
1056 	else
1057 		bch_verbose(c, "done starting filesystem");
1058 	up_write(&c->state_lock);
1059 	return ret;
1060 }
1061 
1062 static int bch2_dev_may_add(struct bch_sb *sb, struct bch_fs *c)
1063 {
1064 	struct bch_member m = bch2_sb_member_get(sb, sb->dev_idx);
1065 
1066 	if (le16_to_cpu(sb->block_size) != block_sectors(c))
1067 		return -BCH_ERR_mismatched_block_size;
1068 
1069 	if (le16_to_cpu(m.bucket_size) <
1070 	    BCH_SB_BTREE_NODE_SIZE(c->disk_sb.sb))
1071 		return -BCH_ERR_bucket_size_too_small;
1072 
1073 	return 0;
1074 }
1075 
1076 static int bch2_dev_in_fs(struct bch_sb_handle *fs,
1077 			  struct bch_sb_handle *sb,
1078 			  struct bch_opts *opts)
1079 {
1080 	if (fs == sb)
1081 		return 0;
1082 
1083 	if (!uuid_equal(&fs->sb->uuid, &sb->sb->uuid))
1084 		return -BCH_ERR_device_not_a_member_of_filesystem;
1085 
1086 	if (!bch2_dev_exists(fs->sb, sb->sb->dev_idx))
1087 		return -BCH_ERR_device_has_been_removed;
1088 
1089 	if (fs->sb->block_size != sb->sb->block_size)
1090 		return -BCH_ERR_mismatched_block_size;
1091 
1092 	if (le16_to_cpu(fs->sb->version) < bcachefs_metadata_version_member_seq ||
1093 	    le16_to_cpu(sb->sb->version) < bcachefs_metadata_version_member_seq)
1094 		return 0;
1095 
1096 	if (fs->sb->seq == sb->sb->seq &&
1097 	    fs->sb->write_time != sb->sb->write_time) {
1098 		struct printbuf buf = PRINTBUF;
1099 
1100 		prt_str(&buf, "Split brain detected between ");
1101 		prt_bdevname(&buf, sb->bdev);
1102 		prt_str(&buf, " and ");
1103 		prt_bdevname(&buf, fs->bdev);
1104 		prt_char(&buf, ':');
1105 		prt_newline(&buf);
1106 		prt_printf(&buf, "seq=%llu but write_time different, got", le64_to_cpu(sb->sb->seq));
1107 		prt_newline(&buf);
1108 
1109 		prt_bdevname(&buf, fs->bdev);
1110 		prt_char(&buf, ' ');
1111 		bch2_prt_datetime(&buf, le64_to_cpu(fs->sb->write_time));;
1112 		prt_newline(&buf);
1113 
1114 		prt_bdevname(&buf, sb->bdev);
1115 		prt_char(&buf, ' ');
1116 		bch2_prt_datetime(&buf, le64_to_cpu(sb->sb->write_time));;
1117 		prt_newline(&buf);
1118 
1119 		if (!opts->no_splitbrain_check)
1120 			prt_printf(&buf, "Not using older sb");
1121 
1122 		pr_err("%s", buf.buf);
1123 		printbuf_exit(&buf);
1124 
1125 		if (!opts->no_splitbrain_check)
1126 			return -BCH_ERR_device_splitbrain;
1127 	}
1128 
1129 	struct bch_member m = bch2_sb_member_get(fs->sb, sb->sb->dev_idx);
1130 	u64 seq_from_fs		= le64_to_cpu(m.seq);
1131 	u64 seq_from_member	= le64_to_cpu(sb->sb->seq);
1132 
1133 	if (seq_from_fs && seq_from_fs < seq_from_member) {
1134 		struct printbuf buf = PRINTBUF;
1135 
1136 		prt_str(&buf, "Split brain detected between ");
1137 		prt_bdevname(&buf, sb->bdev);
1138 		prt_str(&buf, " and ");
1139 		prt_bdevname(&buf, fs->bdev);
1140 		prt_char(&buf, ':');
1141 		prt_newline(&buf);
1142 
1143 		prt_bdevname(&buf, fs->bdev);
1144 		prt_str(&buf, " believes seq of ");
1145 		prt_bdevname(&buf, sb->bdev);
1146 		prt_printf(&buf, " to be %llu, but ", seq_from_fs);
1147 		prt_bdevname(&buf, sb->bdev);
1148 		prt_printf(&buf, " has %llu\n", seq_from_member);
1149 
1150 		if (!opts->no_splitbrain_check) {
1151 			prt_str(&buf, "Not using ");
1152 			prt_bdevname(&buf, sb->bdev);
1153 		}
1154 
1155 		pr_err("%s", buf.buf);
1156 		printbuf_exit(&buf);
1157 
1158 		if (!opts->no_splitbrain_check)
1159 			return -BCH_ERR_device_splitbrain;
1160 	}
1161 
1162 	return 0;
1163 }
1164 
1165 /* Device startup/shutdown: */
1166 
1167 static void bch2_dev_release(struct kobject *kobj)
1168 {
1169 	struct bch_dev *ca = container_of(kobj, struct bch_dev, kobj);
1170 
1171 	kfree(ca);
1172 }
1173 
1174 static void bch2_dev_free(struct bch_dev *ca)
1175 {
1176 	cancel_work_sync(&ca->io_error_work);
1177 
1178 	if (ca->kobj.state_in_sysfs &&
1179 	    ca->disk_sb.bdev)
1180 		sysfs_remove_link(bdev_kobj(ca->disk_sb.bdev), "bcachefs");
1181 
1182 	if (ca->kobj.state_in_sysfs)
1183 		kobject_del(&ca->kobj);
1184 
1185 	bch2_free_super(&ca->disk_sb);
1186 	bch2_dev_journal_exit(ca);
1187 
1188 	free_percpu(ca->io_done);
1189 	bioset_exit(&ca->replica_set);
1190 	bch2_dev_buckets_free(ca);
1191 	free_page((unsigned long) ca->sb_read_scratch);
1192 
1193 	bch2_time_stats_quantiles_exit(&ca->io_latency[WRITE]);
1194 	bch2_time_stats_quantiles_exit(&ca->io_latency[READ]);
1195 
1196 	percpu_ref_exit(&ca->io_ref);
1197 	percpu_ref_exit(&ca->ref);
1198 	kobject_put(&ca->kobj);
1199 }
1200 
1201 static void __bch2_dev_offline(struct bch_fs *c, struct bch_dev *ca)
1202 {
1203 
1204 	lockdep_assert_held(&c->state_lock);
1205 
1206 	if (percpu_ref_is_zero(&ca->io_ref))
1207 		return;
1208 
1209 	__bch2_dev_read_only(c, ca);
1210 
1211 	reinit_completion(&ca->io_ref_completion);
1212 	percpu_ref_kill(&ca->io_ref);
1213 	wait_for_completion(&ca->io_ref_completion);
1214 
1215 	if (ca->kobj.state_in_sysfs) {
1216 		sysfs_remove_link(bdev_kobj(ca->disk_sb.bdev), "bcachefs");
1217 		sysfs_remove_link(&ca->kobj, "block");
1218 	}
1219 
1220 	bch2_free_super(&ca->disk_sb);
1221 	bch2_dev_journal_exit(ca);
1222 }
1223 
1224 static void bch2_dev_ref_complete(struct percpu_ref *ref)
1225 {
1226 	struct bch_dev *ca = container_of(ref, struct bch_dev, ref);
1227 
1228 	complete(&ca->ref_completion);
1229 }
1230 
1231 static void bch2_dev_io_ref_complete(struct percpu_ref *ref)
1232 {
1233 	struct bch_dev *ca = container_of(ref, struct bch_dev, io_ref);
1234 
1235 	complete(&ca->io_ref_completion);
1236 }
1237 
1238 static int bch2_dev_sysfs_online(struct bch_fs *c, struct bch_dev *ca)
1239 {
1240 	int ret;
1241 
1242 	if (!c->kobj.state_in_sysfs)
1243 		return 0;
1244 
1245 	if (!ca->kobj.state_in_sysfs) {
1246 		ret = kobject_add(&ca->kobj, &c->kobj,
1247 				  "dev-%u", ca->dev_idx);
1248 		if (ret)
1249 			return ret;
1250 	}
1251 
1252 	if (ca->disk_sb.bdev) {
1253 		struct kobject *block = bdev_kobj(ca->disk_sb.bdev);
1254 
1255 		ret = sysfs_create_link(block, &ca->kobj, "bcachefs");
1256 		if (ret)
1257 			return ret;
1258 
1259 		ret = sysfs_create_link(&ca->kobj, block, "block");
1260 		if (ret)
1261 			return ret;
1262 	}
1263 
1264 	return 0;
1265 }
1266 
1267 static struct bch_dev *__bch2_dev_alloc(struct bch_fs *c,
1268 					struct bch_member *member)
1269 {
1270 	struct bch_dev *ca;
1271 	unsigned i;
1272 
1273 	ca = kzalloc(sizeof(*ca), GFP_KERNEL);
1274 	if (!ca)
1275 		return NULL;
1276 
1277 	kobject_init(&ca->kobj, &bch2_dev_ktype);
1278 	init_completion(&ca->ref_completion);
1279 	init_completion(&ca->io_ref_completion);
1280 
1281 	init_rwsem(&ca->bucket_lock);
1282 
1283 	INIT_WORK(&ca->io_error_work, bch2_io_error_work);
1284 
1285 	bch2_time_stats_quantiles_init(&ca->io_latency[READ]);
1286 	bch2_time_stats_quantiles_init(&ca->io_latency[WRITE]);
1287 
1288 	ca->mi = bch2_mi_to_cpu(member);
1289 
1290 	for (i = 0; i < ARRAY_SIZE(member->errors); i++)
1291 		atomic64_set(&ca->errors[i], le64_to_cpu(member->errors[i]));
1292 
1293 	ca->uuid = member->uuid;
1294 
1295 	ca->nr_btree_reserve = DIV_ROUND_UP(BTREE_NODE_RESERVE,
1296 			     ca->mi.bucket_size / btree_sectors(c));
1297 
1298 	if (percpu_ref_init(&ca->ref, bch2_dev_ref_complete,
1299 			    0, GFP_KERNEL) ||
1300 	    percpu_ref_init(&ca->io_ref, bch2_dev_io_ref_complete,
1301 			    PERCPU_REF_INIT_DEAD, GFP_KERNEL) ||
1302 	    !(ca->sb_read_scratch = (void *) __get_free_page(GFP_KERNEL)) ||
1303 	    bch2_dev_buckets_alloc(c, ca) ||
1304 	    bioset_init(&ca->replica_set, 4,
1305 			offsetof(struct bch_write_bio, bio), 0) ||
1306 	    !(ca->io_done	= alloc_percpu(*ca->io_done)))
1307 		goto err;
1308 
1309 	return ca;
1310 err:
1311 	bch2_dev_free(ca);
1312 	return NULL;
1313 }
1314 
1315 static void bch2_dev_attach(struct bch_fs *c, struct bch_dev *ca,
1316 			    unsigned dev_idx)
1317 {
1318 	ca->dev_idx = dev_idx;
1319 	__set_bit(ca->dev_idx, ca->self.d);
1320 	scnprintf(ca->name, sizeof(ca->name), "dev-%u", dev_idx);
1321 
1322 	ca->fs = c;
1323 	rcu_assign_pointer(c->devs[ca->dev_idx], ca);
1324 
1325 	if (bch2_dev_sysfs_online(c, ca))
1326 		pr_warn("error creating sysfs objects");
1327 }
1328 
1329 static int bch2_dev_alloc(struct bch_fs *c, unsigned dev_idx)
1330 {
1331 	struct bch_member member = bch2_sb_member_get(c->disk_sb.sb, dev_idx);
1332 	struct bch_dev *ca = NULL;
1333 	int ret = 0;
1334 
1335 	if (bch2_fs_init_fault("dev_alloc"))
1336 		goto err;
1337 
1338 	ca = __bch2_dev_alloc(c, &member);
1339 	if (!ca)
1340 		goto err;
1341 
1342 	ca->fs = c;
1343 
1344 	bch2_dev_attach(c, ca, dev_idx);
1345 	return ret;
1346 err:
1347 	if (ca)
1348 		bch2_dev_free(ca);
1349 	return -BCH_ERR_ENOMEM_dev_alloc;
1350 }
1351 
1352 static int __bch2_dev_attach_bdev(struct bch_dev *ca, struct bch_sb_handle *sb)
1353 {
1354 	unsigned ret;
1355 
1356 	if (bch2_dev_is_online(ca)) {
1357 		bch_err(ca, "already have device online in slot %u",
1358 			sb->sb->dev_idx);
1359 		return -BCH_ERR_device_already_online;
1360 	}
1361 
1362 	if (get_capacity(sb->bdev->bd_disk) <
1363 	    ca->mi.bucket_size * ca->mi.nbuckets) {
1364 		bch_err(ca, "cannot online: device too small");
1365 		return -BCH_ERR_device_size_too_small;
1366 	}
1367 
1368 	BUG_ON(!percpu_ref_is_zero(&ca->io_ref));
1369 
1370 	ret = bch2_dev_journal_init(ca, sb->sb);
1371 	if (ret)
1372 		return ret;
1373 
1374 	/* Commit: */
1375 	ca->disk_sb = *sb;
1376 	memset(sb, 0, sizeof(*sb));
1377 
1378 	ca->dev = ca->disk_sb.bdev->bd_dev;
1379 
1380 	percpu_ref_reinit(&ca->io_ref);
1381 
1382 	return 0;
1383 }
1384 
1385 static int bch2_dev_attach_bdev(struct bch_fs *c, struct bch_sb_handle *sb)
1386 {
1387 	struct bch_dev *ca;
1388 	int ret;
1389 
1390 	lockdep_assert_held(&c->state_lock);
1391 
1392 	if (le64_to_cpu(sb->sb->seq) >
1393 	    le64_to_cpu(c->disk_sb.sb->seq))
1394 		bch2_sb_to_fs(c, sb->sb);
1395 
1396 	BUG_ON(sb->sb->dev_idx >= c->sb.nr_devices ||
1397 	       !c->devs[sb->sb->dev_idx]);
1398 
1399 	ca = bch_dev_locked(c, sb->sb->dev_idx);
1400 
1401 	ret = __bch2_dev_attach_bdev(ca, sb);
1402 	if (ret)
1403 		return ret;
1404 
1405 	bch2_dev_sysfs_online(c, ca);
1406 
1407 	struct printbuf name = PRINTBUF;
1408 	prt_bdevname(&name, ca->disk_sb.bdev);
1409 
1410 	if (c->sb.nr_devices == 1)
1411 		strscpy(c->name, name.buf, sizeof(c->name));
1412 	strscpy(ca->name, name.buf, sizeof(ca->name));
1413 
1414 	printbuf_exit(&name);
1415 
1416 	rebalance_wakeup(c);
1417 	return 0;
1418 }
1419 
1420 /* Device management: */
1421 
1422 /*
1423  * Note: this function is also used by the error paths - when a particular
1424  * device sees an error, we call it to determine whether we can just set the
1425  * device RO, or - if this function returns false - we'll set the whole
1426  * filesystem RO:
1427  *
1428  * XXX: maybe we should be more explicit about whether we're changing state
1429  * because we got an error or what have you?
1430  */
1431 bool bch2_dev_state_allowed(struct bch_fs *c, struct bch_dev *ca,
1432 			    enum bch_member_state new_state, int flags)
1433 {
1434 	struct bch_devs_mask new_online_devs;
1435 	int nr_rw = 0, required;
1436 
1437 	lockdep_assert_held(&c->state_lock);
1438 
1439 	switch (new_state) {
1440 	case BCH_MEMBER_STATE_rw:
1441 		return true;
1442 	case BCH_MEMBER_STATE_ro:
1443 		if (ca->mi.state != BCH_MEMBER_STATE_rw)
1444 			return true;
1445 
1446 		/* do we have enough devices to write to?  */
1447 		for_each_member_device(c, ca2)
1448 			if (ca2 != ca)
1449 				nr_rw += ca2->mi.state == BCH_MEMBER_STATE_rw;
1450 
1451 		required = max(!(flags & BCH_FORCE_IF_METADATA_DEGRADED)
1452 			       ? c->opts.metadata_replicas
1453 			       : metadata_replicas_required(c),
1454 			       !(flags & BCH_FORCE_IF_DATA_DEGRADED)
1455 			       ? c->opts.data_replicas
1456 			       : data_replicas_required(c));
1457 
1458 		return nr_rw >= required;
1459 	case BCH_MEMBER_STATE_failed:
1460 	case BCH_MEMBER_STATE_spare:
1461 		if (ca->mi.state != BCH_MEMBER_STATE_rw &&
1462 		    ca->mi.state != BCH_MEMBER_STATE_ro)
1463 			return true;
1464 
1465 		/* do we have enough devices to read from?  */
1466 		new_online_devs = bch2_online_devs(c);
1467 		__clear_bit(ca->dev_idx, new_online_devs.d);
1468 
1469 		return bch2_have_enough_devs(c, new_online_devs, flags, false);
1470 	default:
1471 		BUG();
1472 	}
1473 }
1474 
1475 static bool bch2_fs_may_start(struct bch_fs *c)
1476 {
1477 	struct bch_dev *ca;
1478 	unsigned i, flags = 0;
1479 
1480 	if (c->opts.very_degraded)
1481 		flags |= BCH_FORCE_IF_DEGRADED|BCH_FORCE_IF_LOST;
1482 
1483 	if (c->opts.degraded)
1484 		flags |= BCH_FORCE_IF_DEGRADED;
1485 
1486 	if (!c->opts.degraded &&
1487 	    !c->opts.very_degraded) {
1488 		mutex_lock(&c->sb_lock);
1489 
1490 		for (i = 0; i < c->disk_sb.sb->nr_devices; i++) {
1491 			if (!bch2_dev_exists(c->disk_sb.sb, i))
1492 				continue;
1493 
1494 			ca = bch_dev_locked(c, i);
1495 
1496 			if (!bch2_dev_is_online(ca) &&
1497 			    (ca->mi.state == BCH_MEMBER_STATE_rw ||
1498 			     ca->mi.state == BCH_MEMBER_STATE_ro)) {
1499 				mutex_unlock(&c->sb_lock);
1500 				return false;
1501 			}
1502 		}
1503 		mutex_unlock(&c->sb_lock);
1504 	}
1505 
1506 	return bch2_have_enough_devs(c, bch2_online_devs(c), flags, true);
1507 }
1508 
1509 static void __bch2_dev_read_only(struct bch_fs *c, struct bch_dev *ca)
1510 {
1511 	/*
1512 	 * The allocator thread itself allocates btree nodes, so stop it first:
1513 	 */
1514 	bch2_dev_allocator_remove(c, ca);
1515 	bch2_dev_journal_stop(&c->journal, ca);
1516 }
1517 
1518 static void __bch2_dev_read_write(struct bch_fs *c, struct bch_dev *ca)
1519 {
1520 	lockdep_assert_held(&c->state_lock);
1521 
1522 	BUG_ON(ca->mi.state != BCH_MEMBER_STATE_rw);
1523 
1524 	bch2_dev_allocator_add(c, ca);
1525 	bch2_recalc_capacity(c);
1526 }
1527 
1528 int __bch2_dev_set_state(struct bch_fs *c, struct bch_dev *ca,
1529 			 enum bch_member_state new_state, int flags)
1530 {
1531 	struct bch_member *m;
1532 	int ret = 0;
1533 
1534 	if (ca->mi.state == new_state)
1535 		return 0;
1536 
1537 	if (!bch2_dev_state_allowed(c, ca, new_state, flags))
1538 		return -BCH_ERR_device_state_not_allowed;
1539 
1540 	if (new_state != BCH_MEMBER_STATE_rw)
1541 		__bch2_dev_read_only(c, ca);
1542 
1543 	bch_notice(ca, "%s", bch2_member_states[new_state]);
1544 
1545 	mutex_lock(&c->sb_lock);
1546 	m = bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx);
1547 	SET_BCH_MEMBER_STATE(m, new_state);
1548 	bch2_write_super(c);
1549 	mutex_unlock(&c->sb_lock);
1550 
1551 	if (new_state == BCH_MEMBER_STATE_rw)
1552 		__bch2_dev_read_write(c, ca);
1553 
1554 	rebalance_wakeup(c);
1555 
1556 	return ret;
1557 }
1558 
1559 int bch2_dev_set_state(struct bch_fs *c, struct bch_dev *ca,
1560 		       enum bch_member_state new_state, int flags)
1561 {
1562 	int ret;
1563 
1564 	down_write(&c->state_lock);
1565 	ret = __bch2_dev_set_state(c, ca, new_state, flags);
1566 	up_write(&c->state_lock);
1567 
1568 	return ret;
1569 }
1570 
1571 /* Device add/removal: */
1572 
1573 static int bch2_dev_remove_alloc(struct bch_fs *c, struct bch_dev *ca)
1574 {
1575 	struct bpos start	= POS(ca->dev_idx, 0);
1576 	struct bpos end		= POS(ca->dev_idx, U64_MAX);
1577 	int ret;
1578 
1579 	/*
1580 	 * We clear the LRU and need_discard btrees first so that we don't race
1581 	 * with bch2_do_invalidates() and bch2_do_discards()
1582 	 */
1583 	ret =   bch2_btree_delete_range(c, BTREE_ID_lru, start, end,
1584 					BTREE_TRIGGER_NORUN, NULL) ?:
1585 		bch2_btree_delete_range(c, BTREE_ID_need_discard, start, end,
1586 					BTREE_TRIGGER_NORUN, NULL) ?:
1587 		bch2_btree_delete_range(c, BTREE_ID_freespace, start, end,
1588 					BTREE_TRIGGER_NORUN, NULL) ?:
1589 		bch2_btree_delete_range(c, BTREE_ID_backpointers, start, end,
1590 					BTREE_TRIGGER_NORUN, NULL) ?:
1591 		bch2_btree_delete_range(c, BTREE_ID_alloc, start, end,
1592 					BTREE_TRIGGER_NORUN, NULL) ?:
1593 		bch2_btree_delete_range(c, BTREE_ID_bucket_gens, start, end,
1594 					BTREE_TRIGGER_NORUN, NULL);
1595 	bch_err_msg(c, ret, "removing dev alloc info");
1596 	return ret;
1597 }
1598 
1599 int bch2_dev_remove(struct bch_fs *c, struct bch_dev *ca, int flags)
1600 {
1601 	struct bch_member *m;
1602 	unsigned dev_idx = ca->dev_idx, data;
1603 	int ret;
1604 
1605 	down_write(&c->state_lock);
1606 
1607 	/*
1608 	 * We consume a reference to ca->ref, regardless of whether we succeed
1609 	 * or fail:
1610 	 */
1611 	percpu_ref_put(&ca->ref);
1612 
1613 	if (!bch2_dev_state_allowed(c, ca, BCH_MEMBER_STATE_failed, flags)) {
1614 		bch_err(ca, "Cannot remove without losing data");
1615 		ret = -BCH_ERR_device_state_not_allowed;
1616 		goto err;
1617 	}
1618 
1619 	__bch2_dev_read_only(c, ca);
1620 
1621 	ret = bch2_dev_data_drop(c, ca->dev_idx, flags);
1622 	bch_err_msg(ca, ret, "bch2_dev_data_drop()");
1623 	if (ret)
1624 		goto err;
1625 
1626 	ret = bch2_dev_remove_alloc(c, ca);
1627 	bch_err_msg(ca, ret, "bch2_dev_remove_alloc()");
1628 	if (ret)
1629 		goto err;
1630 
1631 	ret = bch2_journal_flush_device_pins(&c->journal, ca->dev_idx);
1632 	bch_err_msg(ca, ret, "bch2_journal_flush_device_pins()");
1633 	if (ret)
1634 		goto err;
1635 
1636 	ret = bch2_journal_flush(&c->journal);
1637 	bch_err_msg(ca, ret, "bch2_journal_flush()");
1638 	if (ret)
1639 		goto err;
1640 
1641 	ret = bch2_replicas_gc2(c);
1642 	bch_err_msg(ca, ret, "bch2_replicas_gc2()");
1643 	if (ret)
1644 		goto err;
1645 
1646 	data = bch2_dev_has_data(c, ca);
1647 	if (data) {
1648 		struct printbuf data_has = PRINTBUF;
1649 
1650 		prt_bitflags(&data_has, __bch2_data_types, data);
1651 		bch_err(ca, "Remove failed, still has data (%s)", data_has.buf);
1652 		printbuf_exit(&data_has);
1653 		ret = -EBUSY;
1654 		goto err;
1655 	}
1656 
1657 	__bch2_dev_offline(c, ca);
1658 
1659 	mutex_lock(&c->sb_lock);
1660 	rcu_assign_pointer(c->devs[ca->dev_idx], NULL);
1661 	mutex_unlock(&c->sb_lock);
1662 
1663 	percpu_ref_kill(&ca->ref);
1664 	wait_for_completion(&ca->ref_completion);
1665 
1666 	bch2_dev_free(ca);
1667 
1668 	/*
1669 	 * At this point the device object has been removed in-core, but the
1670 	 * on-disk journal might still refer to the device index via sb device
1671 	 * usage entries. Recovery fails if it sees usage information for an
1672 	 * invalid device. Flush journal pins to push the back of the journal
1673 	 * past now invalid device index references before we update the
1674 	 * superblock, but after the device object has been removed so any
1675 	 * further journal writes elide usage info for the device.
1676 	 */
1677 	bch2_journal_flush_all_pins(&c->journal);
1678 
1679 	/*
1680 	 * Free this device's slot in the bch_member array - all pointers to
1681 	 * this device must be gone:
1682 	 */
1683 	mutex_lock(&c->sb_lock);
1684 	m = bch2_members_v2_get_mut(c->disk_sb.sb, dev_idx);
1685 	memset(&m->uuid, 0, sizeof(m->uuid));
1686 
1687 	bch2_write_super(c);
1688 
1689 	mutex_unlock(&c->sb_lock);
1690 	up_write(&c->state_lock);
1691 
1692 	bch2_dev_usage_journal_reserve(c);
1693 	return 0;
1694 err:
1695 	if (ca->mi.state == BCH_MEMBER_STATE_rw &&
1696 	    !percpu_ref_is_zero(&ca->io_ref))
1697 		__bch2_dev_read_write(c, ca);
1698 	up_write(&c->state_lock);
1699 	return ret;
1700 }
1701 
1702 /* Add new device to running filesystem: */
1703 int bch2_dev_add(struct bch_fs *c, const char *path)
1704 {
1705 	struct bch_opts opts = bch2_opts_empty();
1706 	struct bch_sb_handle sb;
1707 	struct bch_dev *ca = NULL;
1708 	struct bch_sb_field_members_v2 *mi;
1709 	struct bch_member dev_mi;
1710 	unsigned dev_idx, nr_devices, u64s;
1711 	struct printbuf errbuf = PRINTBUF;
1712 	struct printbuf label = PRINTBUF;
1713 	int ret;
1714 
1715 	ret = bch2_read_super(path, &opts, &sb);
1716 	bch_err_msg(c, ret, "reading super");
1717 	if (ret)
1718 		goto err;
1719 
1720 	dev_mi = bch2_sb_member_get(sb.sb, sb.sb->dev_idx);
1721 
1722 	if (BCH_MEMBER_GROUP(&dev_mi)) {
1723 		bch2_disk_path_to_text_sb(&label, sb.sb, BCH_MEMBER_GROUP(&dev_mi) - 1);
1724 		if (label.allocation_failure) {
1725 			ret = -ENOMEM;
1726 			goto err;
1727 		}
1728 	}
1729 
1730 	ret = bch2_dev_may_add(sb.sb, c);
1731 	if (ret)
1732 		goto err;
1733 
1734 	ca = __bch2_dev_alloc(c, &dev_mi);
1735 	if (!ca) {
1736 		ret = -ENOMEM;
1737 		goto err;
1738 	}
1739 
1740 	bch2_dev_usage_init(ca);
1741 
1742 	ret = __bch2_dev_attach_bdev(ca, &sb);
1743 	if (ret)
1744 		goto err;
1745 
1746 	ret = bch2_dev_journal_alloc(ca);
1747 	bch_err_msg(c, ret, "allocating journal");
1748 	if (ret)
1749 		goto err;
1750 
1751 	down_write(&c->state_lock);
1752 	mutex_lock(&c->sb_lock);
1753 
1754 	ret = bch2_sb_from_fs(c, ca);
1755 	bch_err_msg(c, ret, "setting up new superblock");
1756 	if (ret)
1757 		goto err_unlock;
1758 
1759 	if (dynamic_fault("bcachefs:add:no_slot"))
1760 		goto no_slot;
1761 
1762 	for (dev_idx = 0; dev_idx < BCH_SB_MEMBERS_MAX; dev_idx++)
1763 		if (!bch2_dev_exists(c->disk_sb.sb, dev_idx))
1764 			goto have_slot;
1765 no_slot:
1766 	ret = -BCH_ERR_ENOSPC_sb_members;
1767 	bch_err_msg(c, ret, "setting up new superblock");
1768 	goto err_unlock;
1769 
1770 have_slot:
1771 	nr_devices = max_t(unsigned, dev_idx + 1, c->sb.nr_devices);
1772 
1773 	mi = bch2_sb_field_get(c->disk_sb.sb, members_v2);
1774 	u64s = DIV_ROUND_UP(sizeof(struct bch_sb_field_members_v2) +
1775 			    le16_to_cpu(mi->member_bytes) * nr_devices, sizeof(u64));
1776 
1777 	mi = bch2_sb_field_resize(&c->disk_sb, members_v2, u64s);
1778 	if (!mi) {
1779 		ret = -BCH_ERR_ENOSPC_sb_members;
1780 		bch_err_msg(c, ret, "setting up new superblock");
1781 		goto err_unlock;
1782 	}
1783 	struct bch_member *m = bch2_members_v2_get_mut(c->disk_sb.sb, dev_idx);
1784 
1785 	/* success: */
1786 
1787 	*m = dev_mi;
1788 	m->last_mount = cpu_to_le64(ktime_get_real_seconds());
1789 	c->disk_sb.sb->nr_devices	= nr_devices;
1790 
1791 	ca->disk_sb.sb->dev_idx	= dev_idx;
1792 	bch2_dev_attach(c, ca, dev_idx);
1793 
1794 	if (BCH_MEMBER_GROUP(&dev_mi)) {
1795 		ret = __bch2_dev_group_set(c, ca, label.buf);
1796 		bch_err_msg(c, ret, "creating new label");
1797 		if (ret)
1798 			goto err_unlock;
1799 	}
1800 
1801 	bch2_write_super(c);
1802 	mutex_unlock(&c->sb_lock);
1803 
1804 	bch2_dev_usage_journal_reserve(c);
1805 
1806 	ret = bch2_trans_mark_dev_sb(c, ca);
1807 	bch_err_msg(ca, ret, "marking new superblock");
1808 	if (ret)
1809 		goto err_late;
1810 
1811 	ret = bch2_fs_freespace_init(c);
1812 	bch_err_msg(ca, ret, "initializing free space");
1813 	if (ret)
1814 		goto err_late;
1815 
1816 	ca->new_fs_bucket_idx = 0;
1817 
1818 	if (ca->mi.state == BCH_MEMBER_STATE_rw)
1819 		__bch2_dev_read_write(c, ca);
1820 
1821 	up_write(&c->state_lock);
1822 	return 0;
1823 
1824 err_unlock:
1825 	mutex_unlock(&c->sb_lock);
1826 	up_write(&c->state_lock);
1827 err:
1828 	if (ca)
1829 		bch2_dev_free(ca);
1830 	bch2_free_super(&sb);
1831 	printbuf_exit(&label);
1832 	printbuf_exit(&errbuf);
1833 	bch_err_fn(c, ret);
1834 	return ret;
1835 err_late:
1836 	up_write(&c->state_lock);
1837 	ca = NULL;
1838 	goto err;
1839 }
1840 
1841 /* Hot add existing device to running filesystem: */
1842 int bch2_dev_online(struct bch_fs *c, const char *path)
1843 {
1844 	struct bch_opts opts = bch2_opts_empty();
1845 	struct bch_sb_handle sb = { NULL };
1846 	struct bch_dev *ca;
1847 	unsigned dev_idx;
1848 	int ret;
1849 
1850 	down_write(&c->state_lock);
1851 
1852 	ret = bch2_read_super(path, &opts, &sb);
1853 	if (ret) {
1854 		up_write(&c->state_lock);
1855 		return ret;
1856 	}
1857 
1858 	dev_idx = sb.sb->dev_idx;
1859 
1860 	ret = bch2_dev_in_fs(&c->disk_sb, &sb, &c->opts);
1861 	bch_err_msg(c, ret, "bringing %s online", path);
1862 	if (ret)
1863 		goto err;
1864 
1865 	ret = bch2_dev_attach_bdev(c, &sb);
1866 	if (ret)
1867 		goto err;
1868 
1869 	ca = bch_dev_locked(c, dev_idx);
1870 
1871 	ret = bch2_trans_mark_dev_sb(c, ca);
1872 	bch_err_msg(c, ret, "bringing %s online: error from bch2_trans_mark_dev_sb", path);
1873 	if (ret)
1874 		goto err;
1875 
1876 	if (ca->mi.state == BCH_MEMBER_STATE_rw)
1877 		__bch2_dev_read_write(c, ca);
1878 
1879 	if (!ca->mi.freespace_initialized) {
1880 		ret = bch2_dev_freespace_init(c, ca, 0, ca->mi.nbuckets);
1881 		bch_err_msg(ca, ret, "initializing free space");
1882 		if (ret)
1883 			goto err;
1884 	}
1885 
1886 	if (!ca->journal.nr) {
1887 		ret = bch2_dev_journal_alloc(ca);
1888 		bch_err_msg(ca, ret, "allocating journal");
1889 		if (ret)
1890 			goto err;
1891 	}
1892 
1893 	mutex_lock(&c->sb_lock);
1894 	bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx)->last_mount =
1895 		cpu_to_le64(ktime_get_real_seconds());
1896 	bch2_write_super(c);
1897 	mutex_unlock(&c->sb_lock);
1898 
1899 	up_write(&c->state_lock);
1900 	return 0;
1901 err:
1902 	up_write(&c->state_lock);
1903 	bch2_free_super(&sb);
1904 	return ret;
1905 }
1906 
1907 int bch2_dev_offline(struct bch_fs *c, struct bch_dev *ca, int flags)
1908 {
1909 	down_write(&c->state_lock);
1910 
1911 	if (!bch2_dev_is_online(ca)) {
1912 		bch_err(ca, "Already offline");
1913 		up_write(&c->state_lock);
1914 		return 0;
1915 	}
1916 
1917 	if (!bch2_dev_state_allowed(c, ca, BCH_MEMBER_STATE_failed, flags)) {
1918 		bch_err(ca, "Cannot offline required disk");
1919 		up_write(&c->state_lock);
1920 		return -BCH_ERR_device_state_not_allowed;
1921 	}
1922 
1923 	__bch2_dev_offline(c, ca);
1924 
1925 	up_write(&c->state_lock);
1926 	return 0;
1927 }
1928 
1929 int bch2_dev_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
1930 {
1931 	struct bch_member *m;
1932 	u64 old_nbuckets;
1933 	int ret = 0;
1934 
1935 	down_write(&c->state_lock);
1936 	old_nbuckets = ca->mi.nbuckets;
1937 
1938 	if (nbuckets < ca->mi.nbuckets) {
1939 		bch_err(ca, "Cannot shrink yet");
1940 		ret = -EINVAL;
1941 		goto err;
1942 	}
1943 
1944 	if (bch2_dev_is_online(ca) &&
1945 	    get_capacity(ca->disk_sb.bdev->bd_disk) <
1946 	    ca->mi.bucket_size * nbuckets) {
1947 		bch_err(ca, "New size larger than device");
1948 		ret = -BCH_ERR_device_size_too_small;
1949 		goto err;
1950 	}
1951 
1952 	ret = bch2_dev_buckets_resize(c, ca, nbuckets);
1953 	bch_err_msg(ca, ret, "resizing buckets");
1954 	if (ret)
1955 		goto err;
1956 
1957 	ret = bch2_trans_mark_dev_sb(c, ca);
1958 	if (ret)
1959 		goto err;
1960 
1961 	mutex_lock(&c->sb_lock);
1962 	m = bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx);
1963 	m->nbuckets = cpu_to_le64(nbuckets);
1964 
1965 	bch2_write_super(c);
1966 	mutex_unlock(&c->sb_lock);
1967 
1968 	if (ca->mi.freespace_initialized) {
1969 		ret = bch2_dev_freespace_init(c, ca, old_nbuckets, nbuckets);
1970 		if (ret)
1971 			goto err;
1972 
1973 		/*
1974 		 * XXX: this is all wrong transactionally - we'll be able to do
1975 		 * this correctly after the disk space accounting rewrite
1976 		 */
1977 		ca->usage_base->d[BCH_DATA_free].buckets += nbuckets - old_nbuckets;
1978 	}
1979 
1980 	bch2_recalc_capacity(c);
1981 err:
1982 	up_write(&c->state_lock);
1983 	return ret;
1984 }
1985 
1986 /* return with ref on ca->ref: */
1987 struct bch_dev *bch2_dev_lookup(struct bch_fs *c, const char *name)
1988 {
1989 	rcu_read_lock();
1990 	for_each_member_device_rcu(c, ca, NULL)
1991 		if (!strcmp(name, ca->name)) {
1992 			rcu_read_unlock();
1993 			return ca;
1994 		}
1995 	rcu_read_unlock();
1996 	return ERR_PTR(-BCH_ERR_ENOENT_dev_not_found);
1997 }
1998 
1999 /* Filesystem open: */
2000 
2001 static inline int sb_cmp(struct bch_sb *l, struct bch_sb *r)
2002 {
2003 	return  cmp_int(le64_to_cpu(l->seq), le64_to_cpu(r->seq)) ?:
2004 		cmp_int(le64_to_cpu(l->write_time), le64_to_cpu(r->write_time));
2005 }
2006 
2007 struct bch_fs *bch2_fs_open(char * const *devices, unsigned nr_devices,
2008 			    struct bch_opts opts)
2009 {
2010 	DARRAY(struct bch_sb_handle) sbs = { 0 };
2011 	struct bch_fs *c = NULL;
2012 	struct bch_sb_handle *best = NULL;
2013 	struct printbuf errbuf = PRINTBUF;
2014 	int ret = 0;
2015 
2016 	if (!try_module_get(THIS_MODULE))
2017 		return ERR_PTR(-ENODEV);
2018 
2019 	if (!nr_devices) {
2020 		ret = -EINVAL;
2021 		goto err;
2022 	}
2023 
2024 	ret = darray_make_room(&sbs, nr_devices);
2025 	if (ret)
2026 		goto err;
2027 
2028 	for (unsigned i = 0; i < nr_devices; i++) {
2029 		struct bch_sb_handle sb = { NULL };
2030 
2031 		ret = bch2_read_super(devices[i], &opts, &sb);
2032 		if (ret)
2033 			goto err;
2034 
2035 		BUG_ON(darray_push(&sbs, sb));
2036 	}
2037 
2038 	if (opts.nochanges && !opts.read_only) {
2039 		ret = -BCH_ERR_erofs_nochanges;
2040 		goto err_print;
2041 	}
2042 
2043 	darray_for_each(sbs, sb)
2044 		if (!best || sb_cmp(sb->sb, best->sb) > 0)
2045 			best = sb;
2046 
2047 	darray_for_each_reverse(sbs, sb) {
2048 		ret = bch2_dev_in_fs(best, sb, &opts);
2049 
2050 		if (ret == -BCH_ERR_device_has_been_removed ||
2051 		    ret == -BCH_ERR_device_splitbrain) {
2052 			bch2_free_super(sb);
2053 			darray_remove_item(&sbs, sb);
2054 			best -= best > sb;
2055 			ret = 0;
2056 			continue;
2057 		}
2058 
2059 		if (ret)
2060 			goto err_print;
2061 	}
2062 
2063 	c = bch2_fs_alloc(best->sb, opts);
2064 	ret = PTR_ERR_OR_ZERO(c);
2065 	if (ret)
2066 		goto err;
2067 
2068 	down_write(&c->state_lock);
2069 	darray_for_each(sbs, sb) {
2070 		ret = bch2_dev_attach_bdev(c, sb);
2071 		if (ret) {
2072 			up_write(&c->state_lock);
2073 			goto err;
2074 		}
2075 	}
2076 	up_write(&c->state_lock);
2077 
2078 	if (!bch2_fs_may_start(c)) {
2079 		ret = -BCH_ERR_insufficient_devices_to_start;
2080 		goto err_print;
2081 	}
2082 
2083 	if (!c->opts.nostart) {
2084 		ret = bch2_fs_start(c);
2085 		if (ret)
2086 			goto err;
2087 	}
2088 out:
2089 	darray_for_each(sbs, sb)
2090 		bch2_free_super(sb);
2091 	darray_exit(&sbs);
2092 	printbuf_exit(&errbuf);
2093 	module_put(THIS_MODULE);
2094 	return c;
2095 err_print:
2096 	pr_err("bch_fs_open err opening %s: %s",
2097 	       devices[0], bch2_err_str(ret));
2098 err:
2099 	if (!IS_ERR_OR_NULL(c))
2100 		bch2_fs_stop(c);
2101 	c = ERR_PTR(ret);
2102 	goto out;
2103 }
2104 
2105 /* Global interfaces/init */
2106 
2107 static void bcachefs_exit(void)
2108 {
2109 	bch2_debug_exit();
2110 	bch2_vfs_exit();
2111 	bch2_chardev_exit();
2112 	bch2_btree_key_cache_exit();
2113 	if (bcachefs_kset)
2114 		kset_unregister(bcachefs_kset);
2115 }
2116 
2117 static int __init bcachefs_init(void)
2118 {
2119 	bch2_bkey_pack_test();
2120 
2121 	if (!(bcachefs_kset = kset_create_and_add("bcachefs", NULL, fs_kobj)) ||
2122 	    bch2_btree_key_cache_init() ||
2123 	    bch2_chardev_init() ||
2124 	    bch2_vfs_init() ||
2125 	    bch2_debug_init())
2126 		goto err;
2127 
2128 	return 0;
2129 err:
2130 	bcachefs_exit();
2131 	return -ENOMEM;
2132 }
2133 
2134 #define BCH_DEBUG_PARAM(name, description)			\
2135 	bool bch2_##name;					\
2136 	module_param_named(name, bch2_##name, bool, 0644);	\
2137 	MODULE_PARM_DESC(name, description);
2138 BCH_DEBUG_PARAMS()
2139 #undef BCH_DEBUG_PARAM
2140 
2141 __maybe_unused
2142 static unsigned bch2_metadata_version = bcachefs_metadata_version_current;
2143 module_param_named(version, bch2_metadata_version, uint, 0400);
2144 
2145 module_exit(bcachefs_exit);
2146 module_init(bcachefs_init);
2147