Adding upstream version 6.7.7.upstream/6.7.7

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2030 insertions, 0 deletions

diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
new file mode 100644
index 0000000000..818ec467a0
--- /dev/null
+++ b/fs/bcachefs/super.c
@@ -0,0 +1,2030 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * bcachefs setup/teardown code, and some metadata io - read a superblock and
+ * figure out what to do with it.
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcachefs.h"
+#include "alloc_background.h"
+#include "alloc_foreground.h"
+#include "bkey_sort.h"
+#include "btree_cache.h"
+#include "btree_gc.h"
+#include "btree_journal_iter.h"
+#include "btree_key_cache.h"
+#include "btree_update_interior.h"
+#include "btree_io.h"
+#include "btree_write_buffer.h"
+#include "buckets_waiting_for_journal.h"
+#include "chardev.h"
+#include "checksum.h"
+#include "clock.h"
+#include "compress.h"
+#include "counters.h"
+#include "debug.h"
+#include "disk_groups.h"
+#include "ec.h"
+#include "errcode.h"
+#include "error.h"
+#include "fs.h"
+#include "fs-io.h"
+#include "fs-io-buffered.h"
+#include "fs-io-direct.h"
+#include "fsck.h"
+#include "inode.h"
+#include "io_read.h"
+#include "io_write.h"
+#include "journal.h"
+#include "journal_reclaim.h"
+#include "journal_seq_blacklist.h"
+#include "move.h"
+#include "migrate.h"
+#include "movinggc.h"
+#include "nocow_locking.h"
+#include "quota.h"
+#include "rebalance.h"
+#include "recovery.h"
+#include "replicas.h"
+#include "sb-clean.h"
+#include "sb-errors.h"
+#include "sb-members.h"
+#include "snapshot.h"
+#include "subvolume.h"
+#include "super.h"
+#include "super-io.h"
+#include "sysfs.h"
+#include "trace.h"
+
+#include <linux/backing-dev.h>
+#include <linux/blkdev.h>
+#include <linux/debugfs.h>
+#include <linux/device.h>
+#include <linux/idr.h>
+#include <linux/module.h>
+#include <linux/percpu.h>
+#include <linux/random.h>
+#include <linux/sysfs.h>
+#include <crypto/hash.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Kent Overstreet <kent.overstreet@gmail.com>");
+MODULE_DESCRIPTION("bcachefs filesystem");
+MODULE_SOFTDEP("pre: crc32c");
+MODULE_SOFTDEP("pre: crc64");
+MODULE_SOFTDEP("pre: sha256");
+MODULE_SOFTDEP("pre: chacha20");
+MODULE_SOFTDEP("pre: poly1305");
+MODULE_SOFTDEP("pre: xxhash");
+
+#define KTYPE(type)							\
+static const struct attribute_group type ## _group = {			\
+	.attrs = type ## _files						\
+};									\
+									\
+static const struct attribute_group *type ## _groups[] = {		\
+	&type ## _group,						\
+	NULL								\
+};									\
+									\
+static const struct kobj_type type ## _ktype = {			\
+	.release	= type ## _release,				\
+	.sysfs_ops	= &type ## _sysfs_ops,				\
+	.default_groups = type ## _groups				\
+}
+
+static void bch2_fs_release(struct kobject *);
+static void bch2_dev_release(struct kobject *);
+static void bch2_fs_counters_release(struct kobject *k)
+{
+}
+
+static void bch2_fs_internal_release(struct kobject *k)
+{
+}
+
+static void bch2_fs_opts_dir_release(struct kobject *k)
+{
+}
+
+static void bch2_fs_time_stats_release(struct kobject *k)
+{
+}
+
+KTYPE(bch2_fs);
+KTYPE(bch2_fs_counters);
+KTYPE(bch2_fs_internal);
+KTYPE(bch2_fs_opts_dir);
+KTYPE(bch2_fs_time_stats);
+KTYPE(bch2_dev);
+
+static struct kset *bcachefs_kset;
+static LIST_HEAD(bch_fs_list);
+static DEFINE_MUTEX(bch_fs_list_lock);
+
+DECLARE_WAIT_QUEUE_HEAD(bch2_read_only_wait);
+
+static void bch2_dev_free(struct bch_dev *);
+static int bch2_dev_alloc(struct bch_fs *, unsigned);
+static int bch2_dev_sysfs_online(struct bch_fs *, struct bch_dev *);
+static void __bch2_dev_read_only(struct bch_fs *, struct bch_dev *);
+
+struct bch_fs *bch2_dev_to_fs(dev_t dev)
+{
+	struct bch_fs *c;
+	struct bch_dev *ca;
+	unsigned i;
+
+	mutex_lock(&bch_fs_list_lock);
+	rcu_read_lock();
+
+	list_for_each_entry(c, &bch_fs_list, list)
+		for_each_member_device_rcu(ca, c, i, NULL)
+			if (ca->disk_sb.bdev && ca->disk_sb.bdev->bd_dev == dev) {
+				closure_get(&c->cl);
+				goto found;
+			}
+	c = NULL;
+found:
+	rcu_read_unlock();
+	mutex_unlock(&bch_fs_list_lock);
+
+	return c;
+}
+
+static struct bch_fs *__bch2_uuid_to_fs(__uuid_t uuid)
+{
+	struct bch_fs *c;
+
+	lockdep_assert_held(&bch_fs_list_lock);
+
+	list_for_each_entry(c, &bch_fs_list, list)
+		if (!memcmp(&c->disk_sb.sb->uuid, &uuid, sizeof(uuid)))
+			return c;
+
+	return NULL;
+}
+
+struct bch_fs *bch2_uuid_to_fs(__uuid_t uuid)
+{
+	struct bch_fs *c;
+
+	mutex_lock(&bch_fs_list_lock);
+	c = __bch2_uuid_to_fs(uuid);
+	if (c)
+		closure_get(&c->cl);
+	mutex_unlock(&bch_fs_list_lock);
+
+	return c;
+}
+
+static void bch2_dev_usage_journal_reserve(struct bch_fs *c)
+{
+	struct bch_dev *ca;
+	unsigned i, nr = 0, u64s =
+		((sizeof(struct jset_entry_dev_usage) +
+		  sizeof(struct jset_entry_dev_usage_type) * BCH_DATA_NR)) /
+		sizeof(u64);
+
+	rcu_read_lock();
+	for_each_member_device_rcu(ca, c, i, NULL)
+		nr++;
+	rcu_read_unlock();
+
+	bch2_journal_entry_res_resize(&c->journal,
+			&c->dev_usage_journal_res, u64s * nr);
+}
+
+/* Filesystem RO/RW: */
+
+/*
+ * For startup/shutdown of RW stuff, the dependencies are:
+ *
+ * - foreground writes depend on copygc and rebalance (to free up space)
+ *
+ * - copygc and rebalance depend on mark and sweep gc (they actually probably
+ *   don't because they either reserve ahead of time or don't block if
+ *   allocations fail, but allocations can require mark and sweep gc to run
+ *   because of generation number wraparound)
+ *
+ * - all of the above depends on the allocator threads
+ *
+ * - allocator depends on the journal (when it rewrites prios and gens)
+ */
+
+static void __bch2_fs_read_only(struct bch_fs *c)
+{
+	struct bch_dev *ca;
+	unsigned i, clean_passes = 0;
+	u64 seq = 0;
+
+	bch2_fs_ec_stop(c);
+	bch2_open_buckets_stop(c, NULL, true);
+	bch2_rebalance_stop(c);
+	bch2_copygc_stop(c);
+	bch2_gc_thread_stop(c);
+	bch2_fs_ec_flush(c);
+
+	bch_verbose(c, "flushing journal and stopping allocators, journal seq %llu",
+		    journal_cur_seq(&c->journal));
+
+	do {
+		clean_passes++;
+
+		if (bch2_btree_interior_updates_flush(c) ||
+		    bch2_journal_flush_all_pins(&c->journal) ||
+		    bch2_btree_flush_all_writes(c) ||
+		    seq != atomic64_read(&c->journal.seq)) {
+			seq = atomic64_read(&c->journal.seq);
+			clean_passes = 0;
+		}
+	} while (clean_passes < 2);
+
+	bch_verbose(c, "flushing journal and stopping allocators complete, journal seq %llu",
+		    journal_cur_seq(&c->journal));
+
+	if (test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags) &&
+	    !test_bit(BCH_FS_EMERGENCY_RO, &c->flags))
+		set_bit(BCH_FS_CLEAN_SHUTDOWN, &c->flags);
+	bch2_fs_journal_stop(&c->journal);
+
+	/*
+	 * After stopping journal:
+	 */
+	for_each_member_device(ca, c, i)
+		bch2_dev_allocator_remove(c, ca);
+}
+
+#ifndef BCH_WRITE_REF_DEBUG
+static void bch2_writes_disabled(struct percpu_ref *writes)
+{
+	struct bch_fs *c = container_of(writes, struct bch_fs, writes);
+
+	set_bit(BCH_FS_WRITE_DISABLE_COMPLETE, &c->flags);
+	wake_up(&bch2_read_only_wait);
+}
+#endif
+
+void bch2_fs_read_only(struct bch_fs *c)
+{
+	if (!test_bit(BCH_FS_RW, &c->flags)) {
+		bch2_journal_reclaim_stop(&c->journal);
+		return;
+	}
+
+	BUG_ON(test_bit(BCH_FS_WRITE_DISABLE_COMPLETE, &c->flags));
+
+	/*
+	 * Block new foreground-end write operations from starting - any new
+	 * writes will return -EROFS:
+	 */
+	set_bit(BCH_FS_GOING_RO, &c->flags);
+#ifndef BCH_WRITE_REF_DEBUG
+	percpu_ref_kill(&c->writes);
+#else
+	for (unsigned i = 0; i < BCH_WRITE_REF_NR; i++)
+		bch2_write_ref_put(c, i);
+#endif
+
+	/*
+	 * If we're not doing an emergency shutdown, we want to wait on
+	 * outstanding writes to complete so they don't see spurious errors due
+	 * to shutting down the allocator:
+	 *
+	 * If we are doing an emergency shutdown outstanding writes may
+	 * hang until we shutdown the allocator so we don't want to wait
+	 * on outstanding writes before shutting everything down - but
+	 * we do need to wait on them before returning and signalling
+	 * that going RO is complete:
+	 */
+	wait_event(bch2_read_only_wait,
+		   test_bit(BCH_FS_WRITE_DISABLE_COMPLETE, &c->flags) ||
+		   test_bit(BCH_FS_EMERGENCY_RO, &c->flags));
+
+	__bch2_fs_read_only(c);
+
+	wait_event(bch2_read_only_wait,
+		   test_bit(BCH_FS_WRITE_DISABLE_COMPLETE, &c->flags));
+
+	clear_bit(BCH_FS_WRITE_DISABLE_COMPLETE, &c->flags);
+	clear_bit(BCH_FS_GOING_RO, &c->flags);
+
+	if (!bch2_journal_error(&c->journal) &&
+	    !test_bit(BCH_FS_ERROR, &c->flags) &&
+	    !test_bit(BCH_FS_EMERGENCY_RO, &c->flags) &&
+	    test_bit(BCH_FS_STARTED, &c->flags) &&
+	    test_bit(BCH_FS_CLEAN_SHUTDOWN, &c->flags) &&
+	    !c->opts.norecovery) {
+		BUG_ON(c->journal.last_empty_seq != journal_cur_seq(&c->journal));
+		BUG_ON(atomic_read(&c->btree_cache.dirty));
+		BUG_ON(atomic_long_read(&c->btree_key_cache.nr_dirty));
+		BUG_ON(c->btree_write_buffer.state.nr);
+
+		bch_verbose(c, "marking filesystem clean");
+		bch2_fs_mark_clean(c);
+	}
+
+	clear_bit(BCH_FS_RW, &c->flags);
+}
+
+static void bch2_fs_read_only_work(struct work_struct *work)
+{
+	struct bch_fs *c =
+		container_of(work, struct bch_fs, read_only_work);
+
+	down_write(&c->state_lock);
+	bch2_fs_read_only(c);
+	up_write(&c->state_lock);
+}
+
+static void bch2_fs_read_only_async(struct bch_fs *c)
+{
+	queue_work(system_long_wq, &c->read_only_work);
+}
+
+bool bch2_fs_emergency_read_only(struct bch_fs *c)
+{
+	bool ret = !test_and_set_bit(BCH_FS_EMERGENCY_RO, &c->flags);
+
+	bch2_journal_halt(&c->journal);
+	bch2_fs_read_only_async(c);
+
+	wake_up(&bch2_read_only_wait);
+	return ret;
+}
+
+static int bch2_fs_read_write_late(struct bch_fs *c)
+{
+	int ret;
+
+	/*
+	 * Data move operations can't run until after check_snapshots has
+	 * completed, and bch2_snapshot_is_ancestor() is available.
+	 *
+	 * Ideally we'd start copygc/rebalance earlier instead of waiting for
+	 * all of recovery/fsck to complete:
+	 */
+	ret = bch2_copygc_start(c);
+	if (ret) {
+		bch_err(c, "error starting copygc thread");
+		return ret;
+	}
+
+	ret = bch2_rebalance_start(c);
+	if (ret) {
+		bch_err(c, "error starting rebalance thread");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int __bch2_fs_read_write(struct bch_fs *c, bool early)
+{
+	struct bch_dev *ca;
+	unsigned i;
+	int ret;
+
+	if (test_bit(BCH_FS_INITIAL_GC_UNFIXED, &c->flags)) {
+		bch_err(c, "cannot go rw, unfixed btree errors");
+		return -BCH_ERR_erofs_unfixed_errors;
+	}
+
+	if (test_bit(BCH_FS_RW, &c->flags))
+		return 0;
+
+	if (c->opts.norecovery)
+		return -BCH_ERR_erofs_norecovery;
+
+	/*
+	 * nochanges is used for fsck -n mode - we have to allow going rw
+	 * during recovery for that to work:
+	 */
+	if (c->opts.nochanges && (!early || c->opts.read_only))
+		return -BCH_ERR_erofs_nochanges;
+
+	bch_info(c, "going read-write");
+
+	ret = bch2_sb_members_v2_init(c);
+	if (ret)
+		goto err;
+
+	ret = bch2_fs_mark_dirty(c);
+	if (ret)
+		goto err;
+
+	clear_bit(BCH_FS_CLEAN_SHUTDOWN, &c->flags);
+
+	/*
+	 * First journal write must be a flush write: after a clean shutdown we
+	 * don't read the journal, so the first journal write may end up
+	 * overwriting whatever was there previously, and there must always be
+	 * at least one non-flush write in the journal or recovery will fail:
+	 */
+	set_bit(JOURNAL_NEED_FLUSH_WRITE, &c->journal.flags);
+
+	for_each_rw_member(ca, c, i)
+		bch2_dev_allocator_add(c, ca);
+	bch2_recalc_capacity(c);
+
+	set_bit(BCH_FS_RW, &c->flags);
+	set_bit(BCH_FS_WAS_RW, &c->flags);
+
+#ifndef BCH_WRITE_REF_DEBUG
+	percpu_ref_reinit(&c->writes);
+#else
+	for (i = 0; i < BCH_WRITE_REF_NR; i++) {
+		BUG_ON(atomic_long_read(&c->writes[i]));
+		atomic_long_inc(&c->writes[i]);
+	}
+#endif
+
+	ret = bch2_gc_thread_start(c);
+	if (ret) {
+		bch_err(c, "error starting gc thread");
+		return ret;
+	}
+
+	ret = bch2_journal_reclaim_start(&c->journal);
+	if (ret)
+		goto err;
+
+	if (!early) {
+		ret = bch2_fs_read_write_late(c);
+		if (ret)
+			goto err;
+	}
+
+	bch2_do_discards(c);
+	bch2_do_invalidates(c);
+	bch2_do_stripe_deletes(c);
+	bch2_do_pending_node_rewrites(c);
+	return 0;
+err:
+	if (test_bit(BCH_FS_RW, &c->flags))
+		bch2_fs_read_only(c);
+	else
+		__bch2_fs_read_only(c);
+	return ret;
+}
+
+int bch2_fs_read_write(struct bch_fs *c)
+{
+	return __bch2_fs_read_write(c, false);
+}
+
+int bch2_fs_read_write_early(struct bch_fs *c)
+{
+	lockdep_assert_held(&c->state_lock);
+
+	return __bch2_fs_read_write(c, true);
+}
+
+/* Filesystem startup/shutdown: */
+
+static void __bch2_fs_free(struct bch_fs *c)
+{
+	unsigned i;
+
+	for (i = 0; i < BCH_TIME_STAT_NR; i++)
+		bch2_time_stats_exit(&c->times[i]);
+
+	bch2_free_pending_node_rewrites(c);
+	bch2_fs_sb_errors_exit(c);
+	bch2_fs_counters_exit(c);
+	bch2_fs_snapshots_exit(c);
+	bch2_fs_quota_exit(c);
+	bch2_fs_fs_io_direct_exit(c);
+	bch2_fs_fs_io_buffered_exit(c);
+	bch2_fs_fsio_exit(c);
+	bch2_fs_ec_exit(c);
+	bch2_fs_encryption_exit(c);
+	bch2_fs_nocow_locking_exit(c);
+	bch2_fs_io_write_exit(c);
+	bch2_fs_io_read_exit(c);
+	bch2_fs_buckets_waiting_for_journal_exit(c);
+	bch2_fs_btree_interior_update_exit(c);
+	bch2_fs_btree_iter_exit(c);
+	bch2_fs_btree_key_cache_exit(&c->btree_key_cache);
+	bch2_fs_btree_cache_exit(c);
+	bch2_fs_replicas_exit(c);
+	bch2_fs_journal_exit(&c->journal);
+	bch2_io_clock_exit(&c->io_clock[WRITE]);
+	bch2_io_clock_exit(&c->io_clock[READ]);
+	bch2_fs_compress_exit(c);
+	bch2_journal_keys_put_initial(c);
+	BUG_ON(atomic_read(&c->journal_keys.ref));
+	bch2_fs_btree_write_buffer_exit(c);
+	percpu_free_rwsem(&c->mark_lock);
+	free_percpu(c->online_reserved);
+
+	darray_exit(&c->btree_roots_extra);
+	free_percpu(c->pcpu);
+	mempool_exit(&c->large_bkey_pool);
+	mempool_exit(&c->btree_bounce_pool);
+	bioset_exit(&c->btree_bio);
+	mempool_exit(&c->fill_iter);
+#ifndef BCH_WRITE_REF_DEBUG
+	percpu_ref_exit(&c->writes);
+#endif
+	kfree(rcu_dereference_protected(c->disk_groups, 1));
+	kfree(c->journal_seq_blacklist_table);
+	kfree(c->unused_inode_hints);
+
+	if (c->write_ref_wq)
+		destroy_workqueue(c->write_ref_wq);
+	if (c->io_complete_wq)
+		destroy_workqueue(c->io_complete_wq);
+	if (c->copygc_wq)
+		destroy_workqueue(c->copygc_wq);
+	if (c->btree_io_complete_wq)
+		destroy_workqueue(c->btree_io_complete_wq);
+	if (c->btree_update_wq)
+		destroy_workqueue(c->btree_update_wq);
+
+	bch2_free_super(&c->disk_sb);
+	kvpfree(c, sizeof(*c));
+	module_put(THIS_MODULE);
+}
+
+static void bch2_fs_release(struct kobject *kobj)
+{
+	struct bch_fs *c = container_of(kobj, struct bch_fs, kobj);
+
+	__bch2_fs_free(c);
+}
+
+void __bch2_fs_stop(struct bch_fs *c)
+{
+	struct bch_dev *ca;
+	unsigned i;
+
+	bch_verbose(c, "shutting down");
+
+	set_bit(BCH_FS_STOPPING, &c->flags);
+
+	cancel_work_sync(&c->journal_seq_blacklist_gc_work);
+
+	down_write(&c->state_lock);
+	bch2_fs_read_only(c);
+	up_write(&c->state_lock);
+
+	for_each_member_device(ca, c, i)
+		if (ca->kobj.state_in_sysfs &&
+		    ca->disk_sb.bdev)
+			sysfs_remove_link(bdev_kobj(ca->disk_sb.bdev), "bcachefs");
+
+	if (c->kobj.state_in_sysfs)
+		kobject_del(&c->kobj);
+
+	bch2_fs_debug_exit(c);
+	bch2_fs_chardev_exit(c);
+
+	kobject_put(&c->counters_kobj);
+	kobject_put(&c->time_stats);
+	kobject_put(&c->opts_dir);
+	kobject_put(&c->internal);
+
+	/* btree prefetch might have kicked off reads in the background: */
+	bch2_btree_flush_all_reads(c);
+
+	for_each_member_device(ca, c, i)
+		cancel_work_sync(&ca->io_error_work);
+
+	cancel_work_sync(&c->read_only_work);
+}
+
+void bch2_fs_free(struct bch_fs *c)
+{
+	unsigned i;
+
+	mutex_lock(&bch_fs_list_lock);
+	list_del(&c->list);
+	mutex_unlock(&bch_fs_list_lock);
+
+	closure_sync(&c->cl);
+	closure_debug_destroy(&c->cl);
+
+	for (i = 0; i < c->sb.nr_devices; i++) {
+		struct bch_dev *ca = rcu_dereference_protected(c->devs[i], true);
+
+		if (ca) {
+			bch2_free_super(&ca->disk_sb);
+			bch2_dev_free(ca);
+		}
+	}
+
+	bch_verbose(c, "shutdown complete");
+
+	kobject_put(&c->kobj);
+}
+
+void bch2_fs_stop(struct bch_fs *c)
+{
+	__bch2_fs_stop(c);
+	bch2_fs_free(c);
+}
+
+static int bch2_fs_online(struct bch_fs *c)
+{
+	struct bch_dev *ca;
+	unsigned i;
+	int ret = 0;
+
+	lockdep_assert_held(&bch_fs_list_lock);
+
+	if (__bch2_uuid_to_fs(c->sb.uuid)) {
+		bch_err(c, "filesystem UUID already open");
+		return -EINVAL;
+	}
+
+	ret = bch2_fs_chardev_init(c);
+	if (ret) {
+		bch_err(c, "error creating character device");
+		return ret;
+	}
+
+	bch2_fs_debug_init(c);
+
+	ret = kobject_add(&c->kobj, NULL, "%pU", c->sb.user_uuid.b) ?:
+	    kobject_add(&c->internal, &c->kobj, "internal") ?:
+	    kobject_add(&c->opts_dir, &c->kobj, "options") ?:
+	    kobject_add(&c->time_stats, &c->kobj, "time_stats") ?:
+	    kobject_add(&c->counters_kobj, &c->kobj, "counters") ?:
+	    bch2_opts_create_sysfs_files(&c->opts_dir);
+	if (ret) {
+		bch_err(c, "error creating sysfs objects");
+		return ret;
+	}
+
+	down_write(&c->state_lock);
+
+	for_each_member_device(ca, c, i) {
+		ret = bch2_dev_sysfs_online(c, ca);
+		if (ret) {
+			bch_err(c, "error creating sysfs objects");
+			percpu_ref_put(&ca->ref);
+			goto err;
+		}
+	}
+
+	BUG_ON(!list_empty(&c->list));
+	list_add(&c->list, &bch_fs_list);
+err:
+	up_write(&c->state_lock);
+	return ret;
+}
+
+static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
+{
+	struct bch_fs *c;
+	struct printbuf name = PRINTBUF;
+	unsigned i, iter_size;
+	int ret = 0;
+
+	c = kvpmalloc(sizeof(struct bch_fs), GFP_KERNEL|__GFP_ZERO);
+	if (!c) {
+		c = ERR_PTR(-BCH_ERR_ENOMEM_fs_alloc);
+		goto out;
+	}
+
+	__module_get(THIS_MODULE);
+
+	closure_init(&c->cl, NULL);
+
+	c->kobj.kset = bcachefs_kset;
+	kobject_init(&c->kobj, &bch2_fs_ktype);
+	kobject_init(&c->internal, &bch2_fs_internal_ktype);
+	kobject_init(&c->opts_dir, &bch2_fs_opts_dir_ktype);
+	kobject_init(&c->time_stats, &bch2_fs_time_stats_ktype);
+	kobject_init(&c->counters_kobj, &bch2_fs_counters_ktype);
+
+	c->minor		= -1;
+	c->disk_sb.fs_sb	= true;
+
+	init_rwsem(&c->state_lock);
+	mutex_init(&c->sb_lock);
+	mutex_init(&c->replicas_gc_lock);
+	mutex_init(&c->btree_root_lock);
+	INIT_WORK(&c->read_only_work, bch2_fs_read_only_work);
+
+	init_rwsem(&c->gc_lock);
+	mutex_init(&c->gc_gens_lock);
+	atomic_set(&c->journal_keys.ref, 1);
+	c->journal_keys.initial_ref_held = true;
+
+	for (i = 0; i < BCH_TIME_STAT_NR; i++)
+		bch2_time_stats_init(&c->times[i]);
+
+	bch2_fs_copygc_init(c);
+	bch2_fs_btree_key_cache_init_early(&c->btree_key_cache);
+	bch2_fs_btree_iter_init_early(c);
+	bch2_fs_btree_interior_update_init_early(c);
+	bch2_fs_allocator_background_init(c);
+	bch2_fs_allocator_foreground_init(c);
+	bch2_fs_rebalance_init(c);
+	bch2_fs_quota_init(c);
+	bch2_fs_ec_init_early(c);
+	bch2_fs_move_init(c);
+	bch2_fs_sb_errors_init_early(c);
+
+	INIT_LIST_HEAD(&c->list);
+
+	mutex_init(&c->usage_scratch_lock);
+
+	mutex_init(&c->bio_bounce_pages_lock);
+	mutex_init(&c->snapshot_table_lock);
+	init_rwsem(&c->snapshot_create_lock);
+
+	spin_lock_init(&c->btree_write_error_lock);
+
+	INIT_WORK(&c->journal_seq_blacklist_gc_work,
+		  bch2_blacklist_entries_gc);
+
+	INIT_LIST_HEAD(&c->journal_iters);
+
+	INIT_LIST_HEAD(&c->fsck_error_msgs);
+	mutex_init(&c->fsck_error_msgs_lock);
+
+	seqcount_init(&c->gc_pos_lock);
+
+	seqcount_init(&c->usage_lock);
+
+	sema_init(&c->io_in_flight, 128);
+
+	INIT_LIST_HEAD(&c->vfs_inodes_list);
+	mutex_init(&c->vfs_inodes_lock);
+
+	c->copy_gc_enabled		= 1;
+	c->rebalance.enabled		= 1;
+	c->promote_whole_extents	= true;
+
+	c->journal.flush_write_time	= &c->times[BCH_TIME_journal_flush_write];
+	c->journal.noflush_write_time	= &c->times[BCH_TIME_journal_noflush_write];
+	c->journal.blocked_time		= &c->times[BCH_TIME_blocked_journal];
+	c->journal.flush_seq_time	= &c->times[BCH_TIME_journal_flush_seq];
+
+	bch2_fs_btree_cache_init_early(&c->btree_cache);
+
+	mutex_init(&c->sectors_available_lock);
+
+	ret = percpu_init_rwsem(&c->mark_lock);
+	if (ret)
+		goto err;
+
+	mutex_lock(&c->sb_lock);
+	ret = bch2_sb_to_fs(c, sb);
+	mutex_unlock(&c->sb_lock);
+
+	if (ret)
+		goto err;
+
+	pr_uuid(&name, c->sb.user_uuid.b);
+	strscpy(c->name, name.buf, sizeof(c->name));
+	printbuf_exit(&name);
+
+	ret = name.allocation_failure ? -BCH_ERR_ENOMEM_fs_name_alloc : 0;
+	if (ret)
+		goto err;
+
+	/* Compat: */
+	if (le16_to_cpu(sb->version) <= bcachefs_metadata_version_inode_v2 &&
+	    !BCH_SB_JOURNAL_FLUSH_DELAY(sb))
+		SET_BCH_SB_JOURNAL_FLUSH_DELAY(sb, 1000);
+
+	if (le16_to_cpu(sb->version) <= bcachefs_metadata_version_inode_v2 &&
+	    !BCH_SB_JOURNAL_RECLAIM_DELAY(sb))
+		SET_BCH_SB_JOURNAL_RECLAIM_DELAY(sb, 100);
+
+	c->opts = bch2_opts_default;
+	ret = bch2_opts_from_sb(&c->opts, sb);
+	if (ret)
+		goto err;
+
+	bch2_opts_apply(&c->opts, opts);
+
+	c->btree_key_cache_btrees |= 1U << BTREE_ID_alloc;
+	if (c->opts.inodes_use_key_cache)
+		c->btree_key_cache_btrees |= 1U << BTREE_ID_inodes;
+	c->btree_key_cache_btrees |= 1U << BTREE_ID_logged_ops;
+
+	c->block_bits		= ilog2(block_sectors(c));
+	c->btree_foreground_merge_threshold = BTREE_FOREGROUND_MERGE_THRESHOLD(c);
+
+	if (bch2_fs_init_fault("fs_alloc")) {
+		bch_err(c, "fs_alloc fault injected");
+		ret = -EFAULT;
+		goto err;
+	}
+
+	iter_size = sizeof(struct sort_iter) +
+		(btree_blocks(c) + 1) * 2 *
+		sizeof(struct sort_iter_set);
+
+	c->inode_shard_bits = ilog2(roundup_pow_of_two(num_possible_cpus()));
+
+	if (!(c->btree_update_wq = alloc_workqueue("bcachefs",
+				WQ_FREEZABLE|WQ_UNBOUND|WQ_MEM_RECLAIM, 512)) ||
+	    !(c->btree_io_complete_wq = alloc_workqueue("bcachefs_btree_io",
+				WQ_FREEZABLE|WQ_MEM_RECLAIM, 1)) ||
+	    !(c->copygc_wq = alloc_workqueue("bcachefs_copygc",
+				WQ_FREEZABLE|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE, 1)) ||
+	    !(c->io_complete_wq = alloc_workqueue("bcachefs_io",
+				WQ_FREEZABLE|WQ_HIGHPRI|WQ_MEM_RECLAIM, 1)) ||
+	    !(c->write_ref_wq = alloc_workqueue("bcachefs_write_ref",
+				WQ_FREEZABLE, 0)) ||
+#ifndef BCH_WRITE_REF_DEBUG
+	    percpu_ref_init(&c->writes, bch2_writes_disabled,
+			    PERCPU_REF_INIT_DEAD, GFP_KERNEL) ||
+#endif
+	    mempool_init_kmalloc_pool(&c->fill_iter, 1, iter_size) ||
+	    bioset_init(&c->btree_bio, 1,
+			max(offsetof(struct btree_read_bio, bio),
+			    offsetof(struct btree_write_bio, wbio.bio)),
+			BIOSET_NEED_BVECS) ||
+	    !(c->pcpu = alloc_percpu(struct bch_fs_pcpu)) ||
+	    !(c->online_reserved = alloc_percpu(u64)) ||
+	    mempool_init_kvpmalloc_pool(&c->btree_bounce_pool, 1,
+					btree_bytes(c)) ||
+	    mempool_init_kmalloc_pool(&c->large_bkey_pool, 1, 2048) ||
+	    !(c->unused_inode_hints = kcalloc(1U << c->inode_shard_bits,
+					      sizeof(u64), GFP_KERNEL))) {
+		ret = -BCH_ERR_ENOMEM_fs_other_alloc;
+		goto err;
+	}
+
+	ret = bch2_fs_counters_init(c) ?:
+	    bch2_fs_sb_errors_init(c) ?:
+	    bch2_io_clock_init(&c->io_clock[READ]) ?:
+	    bch2_io_clock_init(&c->io_clock[WRITE]) ?:
+	    bch2_fs_journal_init(&c->journal) ?:
+	    bch2_fs_replicas_init(c) ?:
+	    bch2_fs_btree_cache_init(c) ?:
+	    bch2_fs_btree_key_cache_init(&c->btree_key_cache) ?:
+	    bch2_fs_btree_iter_init(c) ?:
+	    bch2_fs_btree_interior_update_init(c) ?:
+	    bch2_fs_buckets_waiting_for_journal_init(c) ?:
+	    bch2_fs_btree_write_buffer_init(c) ?:
+	    bch2_fs_subvolumes_init(c) ?:
+	    bch2_fs_io_read_init(c) ?:
+	    bch2_fs_io_write_init(c) ?:
+	    bch2_fs_nocow_locking_init(c) ?:
+	    bch2_fs_encryption_init(c) ?:
+	    bch2_fs_compress_init(c) ?:
+	    bch2_fs_ec_init(c) ?:
+	    bch2_fs_fsio_init(c) ?:
+	    bch2_fs_fs_io_buffered_init(c) ?:
+	    bch2_fs_fs_io_direct_init(c);
+	if (ret)
+		goto err;
+
+	for (i = 0; i < c->sb.nr_devices; i++)
+		if (bch2_dev_exists(c->disk_sb.sb, i) &&
+		    bch2_dev_alloc(c, i)) {
+			ret = -EEXIST;
+			goto err;
+		}
+
+	bch2_journal_entry_res_resize(&c->journal,
+			&c->btree_root_journal_res,
+			BTREE_ID_NR * (JSET_KEYS_U64s + BKEY_BTREE_PTR_U64s_MAX));
+	bch2_dev_usage_journal_reserve(c);
+	bch2_journal_entry_res_resize(&c->journal,
+			&c->clock_journal_res,
+			(sizeof(struct jset_entry_clock) / sizeof(u64)) * 2);
+
+	mutex_lock(&bch_fs_list_lock);
+	ret = bch2_fs_online(c);
+	mutex_unlock(&bch_fs_list_lock);
+
+	if (ret)
+		goto err;
+out:
+	return c;
+err:
+	bch2_fs_free(c);
+	c = ERR_PTR(ret);
+	goto out;
+}
+
+noinline_for_stack
+static void print_mount_opts(struct bch_fs *c)
+{
+	enum bch_opt_id i;
+	struct printbuf p = PRINTBUF;
+	bool first = true;
+
+	prt_str(&p, "mounting version ");
+	bch2_version_to_text(&p, c->sb.version);
+
+	if (c->opts.read_only) {
+		prt_str(&p, " opts=");
+		first = false;
+		prt_printf(&p, "ro");
+	}
+
+	for (i = 0; i < bch2_opts_nr; i++) {
+		const struct bch_option *opt = &bch2_opt_table[i];
+		u64 v = bch2_opt_get_by_id(&c->opts, i);
+
+		if (!(opt->flags & OPT_MOUNT))
+			continue;
+
+		if (v == bch2_opt_get_by_id(&bch2_opts_default, i))
+			continue;
+
+		prt_str(&p, first ? " opts=" : ",");
+		first = false;
+		bch2_opt_to_text(&p, c, c->disk_sb.sb, opt, v, OPT_SHOW_MOUNT_STYLE);
+	}
+
+	bch_info(c, "%s", p.buf);
+	printbuf_exit(&p);
+}
+
+int bch2_fs_start(struct bch_fs *c)
+{
+	struct bch_dev *ca;
+	time64_t now = ktime_get_real_seconds();
+	unsigned i;
+	int ret;
+
+	print_mount_opts(c);
+
+	down_write(&c->state_lock);
+
+	BUG_ON(test_bit(BCH_FS_STARTED, &c->flags));
+
+	mutex_lock(&c->sb_lock);
+
+	ret = bch2_sb_members_v2_init(c);
+	if (ret) {
+		mutex_unlock(&c->sb_lock);
+		goto err;
+	}
+
+	for_each_online_member(ca, c, i)
+		bch2_members_v2_get_mut(c->disk_sb.sb, i)->last_mount = cpu_to_le64(now);
+
+	mutex_unlock(&c->sb_lock);
+
+	for_each_rw_member(ca, c, i)
+		bch2_dev_allocator_add(c, ca);
+	bch2_recalc_capacity(c);
+
+	ret = BCH_SB_INITIALIZED(c->disk_sb.sb)
+		? bch2_fs_recovery(c)
+		: bch2_fs_initialize(c);
+	if (ret)
+		goto err;
+
+	ret = bch2_opts_check_may_set(c);
+	if (ret)
+		goto err;
+
+	if (bch2_fs_init_fault("fs_start")) {
+		bch_err(c, "fs_start fault injected");
+		ret = -EINVAL;
+		goto err;
+	}
+
+	set_bit(BCH_FS_STARTED, &c->flags);
+
+	if (c->opts.read_only || c->opts.nochanges) {
+		bch2_fs_read_only(c);
+	} else {
+		ret = !test_bit(BCH_FS_RW, &c->flags)
+			? bch2_fs_read_write(c)
+			: bch2_fs_read_write_late(c);
+		if (ret)
+			goto err;
+	}
+
+	ret = 0;
+out:
+	up_write(&c->state_lock);
+	return ret;
+err:
+	bch_err_msg(c, ret, "starting filesystem");
+	goto out;
+}
+
+static int bch2_dev_may_add(struct bch_sb *sb, struct bch_fs *c)
+{
+	struct bch_member m = bch2_sb_member_get(sb, sb->dev_idx);
+
+	if (le16_to_cpu(sb->block_size) != block_sectors(c))
+		return -BCH_ERR_mismatched_block_size;
+
+	if (le16_to_cpu(m.bucket_size) <
+	    BCH_SB_BTREE_NODE_SIZE(c->disk_sb.sb))
+		return -BCH_ERR_bucket_size_too_small;
+
+	return 0;
+}
+
+static int bch2_dev_in_fs(struct bch_sb *fs, struct bch_sb *sb)
+{
+	struct bch_sb *newest =
+		le64_to_cpu(fs->seq) > le64_to_cpu(sb->seq) ? fs : sb;
+
+	if (!uuid_equal(&fs->uuid, &sb->uuid))
+		return -BCH_ERR_device_not_a_member_of_filesystem;
+
+	if (!bch2_dev_exists(newest, sb->dev_idx))
+		return -BCH_ERR_device_has_been_removed;
+
+	if (fs->block_size != sb->block_size)
+		return -BCH_ERR_mismatched_block_size;
+
+	return 0;
+}
+
+/* Device startup/shutdown: */
+
+static void bch2_dev_release(struct kobject *kobj)
+{
+	struct bch_dev *ca = container_of(kobj, struct bch_dev, kobj);
+
+	kfree(ca);
+}
+
+static void bch2_dev_free(struct bch_dev *ca)
+{
+	cancel_work_sync(&ca->io_error_work);
+
+	if (ca->kobj.state_in_sysfs &&
+	    ca->disk_sb.bdev)
+		sysfs_remove_link(bdev_kobj(ca->disk_sb.bdev), "bcachefs");
+
+	if (ca->kobj.state_in_sysfs)
+		kobject_del(&ca->kobj);
+
+	bch2_free_super(&ca->disk_sb);
+	bch2_dev_journal_exit(ca);
+
+	free_percpu(ca->io_done);
+	bioset_exit(&ca->replica_set);
+	bch2_dev_buckets_free(ca);
+	free_page((unsigned long) ca->sb_read_scratch);
+
+	bch2_time_stats_exit(&ca->io_latency[WRITE]);
+	bch2_time_stats_exit(&ca->io_latency[READ]);
+
+	percpu_ref_exit(&ca->io_ref);
+	percpu_ref_exit(&ca->ref);
+	kobject_put(&ca->kobj);
+}
+
+static void __bch2_dev_offline(struct bch_fs *c, struct bch_dev *ca)
+{
+
+	lockdep_assert_held(&c->state_lock);
+
+	if (percpu_ref_is_zero(&ca->io_ref))
+		return;
+
+	__bch2_dev_read_only(c, ca);
+
+	reinit_completion(&ca->io_ref_completion);
+	percpu_ref_kill(&ca->io_ref);
+	wait_for_completion(&ca->io_ref_completion);
+
+	if (ca->kobj.state_in_sysfs) {
+		sysfs_remove_link(bdev_kobj(ca->disk_sb.bdev), "bcachefs");
+		sysfs_remove_link(&ca->kobj, "block");
+	}
+
+	bch2_free_super(&ca->disk_sb);
+	bch2_dev_journal_exit(ca);
+}
+
+static void bch2_dev_ref_complete(struct percpu_ref *ref)
+{
+	struct bch_dev *ca = container_of(ref, struct bch_dev, ref);
+
+	complete(&ca->ref_completion);
+}
+
+static void bch2_dev_io_ref_complete(struct percpu_ref *ref)
+{
+	struct bch_dev *ca = container_of(ref, struct bch_dev, io_ref);
+
+	complete(&ca->io_ref_completion);
+}
+
+static int bch2_dev_sysfs_online(struct bch_fs *c, struct bch_dev *ca)
+{
+	int ret;
+
+	if (!c->kobj.state_in_sysfs)
+		return 0;
+
+	if (!ca->kobj.state_in_sysfs) {
+		ret = kobject_add(&ca->kobj, &c->kobj,
+				  "dev-%u", ca->dev_idx);
+		if (ret)
+			return ret;
+	}
+
+	if (ca->disk_sb.bdev) {
+		struct kobject *block = bdev_kobj(ca->disk_sb.bdev);
+
+		ret = sysfs_create_link(block, &ca->kobj, "bcachefs");
+		if (ret)
+			return ret;
+
+		ret = sysfs_create_link(&ca->kobj, block, "block");
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static struct bch_dev *__bch2_dev_alloc(struct bch_fs *c,
+					struct bch_member *member)
+{
+	struct bch_dev *ca;
+	unsigned i;
+
+	ca = kzalloc(sizeof(*ca), GFP_KERNEL);
+	if (!ca)
+		return NULL;
+
+	kobject_init(&ca->kobj, &bch2_dev_ktype);
+	init_completion(&ca->ref_completion);
+	init_completion(&ca->io_ref_completion);
+
+	init_rwsem(&ca->bucket_lock);
+
+	INIT_WORK(&ca->io_error_work, bch2_io_error_work);
+
+	bch2_time_stats_init(&ca->io_latency[READ]);
+	bch2_time_stats_init(&ca->io_latency[WRITE]);
+
+	ca->mi = bch2_mi_to_cpu(member);
+
+	for (i = 0; i < ARRAY_SIZE(member->errors); i++)
+		atomic64_set(&ca->errors[i], le64_to_cpu(member->errors[i]));
+
+	ca->uuid = member->uuid;
+
+	ca->nr_btree_reserve = DIV_ROUND_UP(BTREE_NODE_RESERVE,
+			     ca->mi.bucket_size / btree_sectors(c));
+
+	if (percpu_ref_init(&ca->ref, bch2_dev_ref_complete,
+			    0, GFP_KERNEL) ||
+	    percpu_ref_init(&ca->io_ref, bch2_dev_io_ref_complete,
+			    PERCPU_REF_INIT_DEAD, GFP_KERNEL) ||
+	    !(ca->sb_read_scratch = (void *) __get_free_page(GFP_KERNEL)) ||
+	    bch2_dev_buckets_alloc(c, ca) ||
+	    bioset_init(&ca->replica_set, 4,
+			offsetof(struct bch_write_bio, bio), 0) ||
+	    !(ca->io_done	= alloc_percpu(*ca->io_done)))
+		goto err;
+
+	return ca;
+err:
+	bch2_dev_free(ca);
+	return NULL;
+}
+
+static void bch2_dev_attach(struct bch_fs *c, struct bch_dev *ca,
+			    unsigned dev_idx)
+{
+	ca->dev_idx = dev_idx;
+	__set_bit(ca->dev_idx, ca->self.d);
+	scnprintf(ca->name, sizeof(ca->name), "dev-%u", dev_idx);
+
+	ca->fs = c;
+	rcu_assign_pointer(c->devs[ca->dev_idx], ca);
+
+	if (bch2_dev_sysfs_online(c, ca))
+		pr_warn("error creating sysfs objects");
+}
+
+static int bch2_dev_alloc(struct bch_fs *c, unsigned dev_idx)
+{
+	struct bch_member member = bch2_sb_member_get(c->disk_sb.sb, dev_idx);
+	struct bch_dev *ca = NULL;
+	int ret = 0;
+
+	if (bch2_fs_init_fault("dev_alloc"))
+		goto err;
+
+	ca = __bch2_dev_alloc(c, &member);
+	if (!ca)
+		goto err;
+
+	ca->fs = c;
+
+	bch2_dev_attach(c, ca, dev_idx);
+	return ret;
+err:
+	if (ca)
+		bch2_dev_free(ca);
+	return -BCH_ERR_ENOMEM_dev_alloc;
+}
+
+static int __bch2_dev_attach_bdev(struct bch_dev *ca, struct bch_sb_handle *sb)
+{
+	unsigned ret;
+
+	if (bch2_dev_is_online(ca)) {
+		bch_err(ca, "already have device online in slot %u",
+			sb->sb->dev_idx);
+		return -BCH_ERR_device_already_online;
+	}
+
+	if (get_capacity(sb->bdev->bd_disk) <
+	    ca->mi.bucket_size * ca->mi.nbuckets) {
+		bch_err(ca, "cannot online: device too small");
+		return -BCH_ERR_device_size_too_small;
+	}
+
+	BUG_ON(!percpu_ref_is_zero(&ca->io_ref));
+
+	ret = bch2_dev_journal_init(ca, sb->sb);
+	if (ret)
+		return ret;
+
+	/* Commit: */
+	ca->disk_sb = *sb;
+	memset(sb, 0, sizeof(*sb));
+
+	ca->dev = ca->disk_sb.bdev->bd_dev;
+
+	percpu_ref_reinit(&ca->io_ref);
+
+	return 0;
+}
+
+static int bch2_dev_attach_bdev(struct bch_fs *c, struct bch_sb_handle *sb)
+{
+	struct bch_dev *ca;
+	int ret;
+
+	lockdep_assert_held(&c->state_lock);
+
+	if (le64_to_cpu(sb->sb->seq) >
+	    le64_to_cpu(c->disk_sb.sb->seq))
+		bch2_sb_to_fs(c, sb->sb);
+
+	BUG_ON(sb->sb->dev_idx >= c->sb.nr_devices ||
+	       !c->devs[sb->sb->dev_idx]);
+
+	ca = bch_dev_locked(c, sb->sb->dev_idx);
+
+	ret = __bch2_dev_attach_bdev(ca, sb);
+	if (ret)
+		return ret;
+
+	bch2_dev_sysfs_online(c, ca);
+
+	if (c->sb.nr_devices == 1)
+		snprintf(c->name, sizeof(c->name), "%pg", ca->disk_sb.bdev);
+	snprintf(ca->name, sizeof(ca->name), "%pg", ca->disk_sb.bdev);
+
+	rebalance_wakeup(c);
+	return 0;
+}
+
+/* Device management: */
+
+/*
+ * Note: this function is also used by the error paths - when a particular
+ * device sees an error, we call it to determine whether we can just set the
+ * device RO, or - if this function returns false - we'll set the whole
+ * filesystem RO:
+ *
+ * XXX: maybe we should be more explicit about whether we're changing state
+ * because we got an error or what have you?
+ */
+bool bch2_dev_state_allowed(struct bch_fs *c, struct bch_dev *ca,
+			    enum bch_member_state new_state, int flags)
+{
+	struct bch_devs_mask new_online_devs;
+	struct bch_dev *ca2;
+	int i, nr_rw = 0, required;
+
+	lockdep_assert_held(&c->state_lock);
+
+	switch (new_state) {
+	case BCH_MEMBER_STATE_rw:
+		return true;
+	case BCH_MEMBER_STATE_ro:
+		if (ca->mi.state != BCH_MEMBER_STATE_rw)
+			return true;
+
+		/* do we have enough devices to write to?  */
+		for_each_member_device(ca2, c, i)
+			if (ca2 != ca)
+				nr_rw += ca2->mi.state == BCH_MEMBER_STATE_rw;
+
+		required = max(!(flags & BCH_FORCE_IF_METADATA_DEGRADED)
+			       ? c->opts.metadata_replicas
+			       : c->opts.metadata_replicas_required,
+			       !(flags & BCH_FORCE_IF_DATA_DEGRADED)
+			       ? c->opts.data_replicas
+			       : c->opts.data_replicas_required);
+
+		return nr_rw >= required;
+	case BCH_MEMBER_STATE_failed:
+	case BCH_MEMBER_STATE_spare:
+		if (ca->mi.state != BCH_MEMBER_STATE_rw &&
+		    ca->mi.state != BCH_MEMBER_STATE_ro)
+			return true;
+
+		/* do we have enough devices to read from?  */
+		new_online_devs = bch2_online_devs(c);
+		__clear_bit(ca->dev_idx, new_online_devs.d);
+
+		return bch2_have_enough_devs(c, new_online_devs, flags, false);
+	default:
+		BUG();
+	}
+}
+
+static bool bch2_fs_may_start(struct bch_fs *c)
+{
+	struct bch_dev *ca;
+	unsigned i, flags = 0;
+
+	if (c->opts.very_degraded)
+		flags |= BCH_FORCE_IF_DEGRADED|BCH_FORCE_IF_LOST;
+
+	if (c->opts.degraded)
+		flags |= BCH_FORCE_IF_DEGRADED;
+
+	if (!c->opts.degraded &&
+	    !c->opts.very_degraded) {
+		mutex_lock(&c->sb_lock);
+
+		for (i = 0; i < c->disk_sb.sb->nr_devices; i++) {
+			if (!bch2_dev_exists(c->disk_sb.sb, i))
+				continue;
+
+			ca = bch_dev_locked(c, i);
+
+			if (!bch2_dev_is_online(ca) &&
+			    (ca->mi.state == BCH_MEMBER_STATE_rw ||
+			     ca->mi.state == BCH_MEMBER_STATE_ro)) {
+				mutex_unlock(&c->sb_lock);
+				return false;
+			}
+		}
+		mutex_unlock(&c->sb_lock);
+	}
+
+	return bch2_have_enough_devs(c, bch2_online_devs(c), flags, true);
+}
+
+static void __bch2_dev_read_only(struct bch_fs *c, struct bch_dev *ca)
+{
+	/*
+	 * The allocator thread itself allocates btree nodes, so stop it first:
+	 */
+	bch2_dev_allocator_remove(c, ca);
+	bch2_dev_journal_stop(&c->journal, ca);
+}
+
+static void __bch2_dev_read_write(struct bch_fs *c, struct bch_dev *ca)
+{
+	lockdep_assert_held(&c->state_lock);
+
+	BUG_ON(ca->mi.state != BCH_MEMBER_STATE_rw);
+
+	bch2_dev_allocator_add(c, ca);
+	bch2_recalc_capacity(c);
+}
+
+int __bch2_dev_set_state(struct bch_fs *c, struct bch_dev *ca,
+			 enum bch_member_state new_state, int flags)
+{
+	struct bch_member *m;
+	int ret = 0;
+
+	if (ca->mi.state == new_state)
+		return 0;
+
+	if (!bch2_dev_state_allowed(c, ca, new_state, flags))
+		return -BCH_ERR_device_state_not_allowed;
+
+	if (new_state != BCH_MEMBER_STATE_rw)
+		__bch2_dev_read_only(c, ca);
+
+	bch_notice(ca, "%s", bch2_member_states[new_state]);
+
+	mutex_lock(&c->sb_lock);
+	m = bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx);
+	SET_BCH_MEMBER_STATE(m, new_state);
+	bch2_write_super(c);
+	mutex_unlock(&c->sb_lock);
+
+	if (new_state == BCH_MEMBER_STATE_rw)
+		__bch2_dev_read_write(c, ca);
+
+	rebalance_wakeup(c);
+
+	return ret;
+}
+
+int bch2_dev_set_state(struct bch_fs *c, struct bch_dev *ca,
+		       enum bch_member_state new_state, int flags)
+{
+	int ret;
+
+	down_write(&c->state_lock);
+	ret = __bch2_dev_set_state(c, ca, new_state, flags);
+	up_write(&c->state_lock);
+
+	return ret;
+}
+
+/* Device add/removal: */
+
+static int bch2_dev_remove_alloc(struct bch_fs *c, struct bch_dev *ca)
+{
+	struct bpos start	= POS(ca->dev_idx, 0);
+	struct bpos end		= POS(ca->dev_idx, U64_MAX);
+	int ret;
+
+	/*
+	 * We clear the LRU and need_discard btrees first so that we don't race
+	 * with bch2_do_invalidates() and bch2_do_discards()
+	 */
+	ret =   bch2_btree_delete_range(c, BTREE_ID_lru, start, end,
+					BTREE_TRIGGER_NORUN, NULL) ?:
+		bch2_btree_delete_range(c, BTREE_ID_need_discard, start, end,
+					BTREE_TRIGGER_NORUN, NULL) ?:
+		bch2_btree_delete_range(c, BTREE_ID_freespace, start, end,
+					BTREE_TRIGGER_NORUN, NULL) ?:
+		bch2_btree_delete_range(c, BTREE_ID_backpointers, start, end,
+					BTREE_TRIGGER_NORUN, NULL) ?:
+		bch2_btree_delete_range(c, BTREE_ID_alloc, start, end,
+					BTREE_TRIGGER_NORUN, NULL) ?:
+		bch2_btree_delete_range(c, BTREE_ID_bucket_gens, start, end,
+					BTREE_TRIGGER_NORUN, NULL);
+	if (ret)
+		bch_err_msg(c, ret, "removing dev alloc info");
+
+	return ret;
+}
+
+int bch2_dev_remove(struct bch_fs *c, struct bch_dev *ca, int flags)
+{
+	struct bch_member *m;
+	unsigned dev_idx = ca->dev_idx, data;
+	int ret;
+
+	down_write(&c->state_lock);
+
+	/*
+	 * We consume a reference to ca->ref, regardless of whether we succeed
+	 * or fail:
+	 */
+	percpu_ref_put(&ca->ref);
+
+	if (!bch2_dev_state_allowed(c, ca, BCH_MEMBER_STATE_failed, flags)) {
+		bch_err(ca, "Cannot remove without losing data");
+		ret = -BCH_ERR_device_state_not_allowed;
+		goto err;
+	}
+
+	__bch2_dev_read_only(c, ca);
+
+	ret = bch2_dev_data_drop(c, ca->dev_idx, flags);
+	if (ret) {
+		bch_err_msg(ca, ret, "dropping data");
+		goto err;
+	}
+
+	ret = bch2_dev_remove_alloc(c, ca);
+	if (ret) {
+		bch_err_msg(ca, ret, "deleting alloc info");
+		goto err;
+	}
+
+	ret = bch2_journal_flush_device_pins(&c->journal, ca->dev_idx);
+	if (ret) {
+		bch_err_msg(ca, ret, "flushing journal");
+		goto err;
+	}
+
+	ret = bch2_journal_flush(&c->journal);
+	if (ret) {
+		bch_err(ca, "journal error");
+		goto err;
+	}
+
+	ret = bch2_replicas_gc2(c);
+	if (ret) {
+		bch_err_msg(ca, ret, "in replicas_gc2()");
+		goto err;
+	}
+
+	data = bch2_dev_has_data(c, ca);
+	if (data) {
+		struct printbuf data_has = PRINTBUF;
+
+		prt_bitflags(&data_has, bch2_data_types, data);
+		bch_err(ca, "Remove failed, still has data (%s)", data_has.buf);
+		printbuf_exit(&data_has);
+		ret = -EBUSY;
+		goto err;
+	}
+
+	__bch2_dev_offline(c, ca);
+
+	mutex_lock(&c->sb_lock);
+	rcu_assign_pointer(c->devs[ca->dev_idx], NULL);
+	mutex_unlock(&c->sb_lock);
+
+	percpu_ref_kill(&ca->ref);
+	wait_for_completion(&ca->ref_completion);
+
+	bch2_dev_free(ca);
+
+	/*
+	 * At this point the device object has been removed in-core, but the
+	 * on-disk journal might still refer to the device index via sb device
+	 * usage entries. Recovery fails if it sees usage information for an
+	 * invalid device. Flush journal pins to push the back of the journal
+	 * past now invalid device index references before we update the
+	 * superblock, but after the device object has been removed so any
+	 * further journal writes elide usage info for the device.
+	 */
+	bch2_journal_flush_all_pins(&c->journal);
+
+	/*
+	 * Free this device's slot in the bch_member array - all pointers to
+	 * this device must be gone:
+	 */
+	mutex_lock(&c->sb_lock);
+	m = bch2_members_v2_get_mut(c->disk_sb.sb, dev_idx);
+	memset(&m->uuid, 0, sizeof(m->uuid));
+
+	bch2_write_super(c);
+
+	mutex_unlock(&c->sb_lock);
+	up_write(&c->state_lock);
+
+	bch2_dev_usage_journal_reserve(c);
+	return 0;
+err:
+	if (ca->mi.state == BCH_MEMBER_STATE_rw &&
+	    !percpu_ref_is_zero(&ca->io_ref))
+		__bch2_dev_read_write(c, ca);
+	up_write(&c->state_lock);
+	return ret;
+}
+
+/* Add new device to running filesystem: */
+int bch2_dev_add(struct bch_fs *c, const char *path)
+{
+	struct bch_opts opts = bch2_opts_empty();
+	struct bch_sb_handle sb;
+	struct bch_dev *ca = NULL;
+	struct bch_sb_field_members_v2 *mi;
+	struct bch_member dev_mi;
+	unsigned dev_idx, nr_devices, u64s;
+	struct printbuf errbuf = PRINTBUF;
+	struct printbuf label = PRINTBUF;
+	int ret;
+
+	ret = bch2_read_super(path, &opts, &sb);
+	if (ret) {
+		bch_err_msg(c, ret, "reading super");
+		goto err;
+	}
+
+	dev_mi = bch2_sb_member_get(sb.sb, sb.sb->dev_idx);
+
+	if (BCH_MEMBER_GROUP(&dev_mi)) {
+		bch2_disk_path_to_text_sb(&label, sb.sb, BCH_MEMBER_GROUP(&dev_mi) - 1);
+		if (label.allocation_failure) {
+			ret = -ENOMEM;
+			goto err;
+		}
+	}
+
+	ret = bch2_dev_may_add(sb.sb, c);
+	if (ret) {
+		bch_err_fn(c, ret);
+		goto err;
+	}
+
+	ca = __bch2_dev_alloc(c, &dev_mi);
+	if (!ca) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	bch2_dev_usage_init(ca);
+
+	ret = __bch2_dev_attach_bdev(ca, &sb);
+	if (ret)
+		goto err;
+
+	ret = bch2_dev_journal_alloc(ca);
+	if (ret) {
+		bch_err_msg(c, ret, "allocating journal");
+		goto err;
+	}
+
+	down_write(&c->state_lock);
+	mutex_lock(&c->sb_lock);
+
+	ret = bch2_sb_from_fs(c, ca);
+	if (ret) {
+		bch_err_msg(c, ret, "setting up new superblock");
+		goto err_unlock;
+	}
+
+	if (dynamic_fault("bcachefs:add:no_slot"))
+		goto no_slot;
+
+	for (dev_idx = 0; dev_idx < BCH_SB_MEMBERS_MAX; dev_idx++)
+		if (!bch2_dev_exists(c->disk_sb.sb, dev_idx))
+			goto have_slot;
+no_slot:
+	ret = -BCH_ERR_ENOSPC_sb_members;
+	bch_err_msg(c, ret, "setting up new superblock");
+	goto err_unlock;
+
+have_slot:
+	nr_devices = max_t(unsigned, dev_idx + 1, c->sb.nr_devices);
+
+	mi = bch2_sb_field_get(c->disk_sb.sb, members_v2);
+	u64s = DIV_ROUND_UP(sizeof(struct bch_sb_field_members_v2) +
+			    le16_to_cpu(mi->member_bytes) * nr_devices, sizeof(u64));
+
+	mi = bch2_sb_field_resize(&c->disk_sb, members_v2, u64s);
+	if (!mi) {
+		ret = -BCH_ERR_ENOSPC_sb_members;
+		bch_err_msg(c, ret, "setting up new superblock");
+		goto err_unlock;
+	}
+	struct bch_member *m = bch2_members_v2_get_mut(c->disk_sb.sb, dev_idx);
+
+	/* success: */
+
+	*m = dev_mi;
+	m->last_mount = cpu_to_le64(ktime_get_real_seconds());
+	c->disk_sb.sb->nr_devices	= nr_devices;
+
+	ca->disk_sb.sb->dev_idx	= dev_idx;
+	bch2_dev_attach(c, ca, dev_idx);
+
+	if (BCH_MEMBER_GROUP(&dev_mi)) {
+		ret = __bch2_dev_group_set(c, ca, label.buf);
+		if (ret) {
+			bch_err_msg(c, ret, "creating new label");
+			goto err_unlock;
+		}
+	}
+
+	bch2_write_super(c);
+	mutex_unlock(&c->sb_lock);
+
+	bch2_dev_usage_journal_reserve(c);
+
+	ret = bch2_trans_mark_dev_sb(c, ca);
+	if (ret) {
+		bch_err_msg(ca, ret, "marking new superblock");
+		goto err_late;
+	}
+
+	ret = bch2_fs_freespace_init(c);
+	if (ret) {
+		bch_err_msg(ca, ret, "initializing free space");
+		goto err_late;
+	}
+
+	ca->new_fs_bucket_idx = 0;
+
+	if (ca->mi.state == BCH_MEMBER_STATE_rw)
+		__bch2_dev_read_write(c, ca);
+
+	up_write(&c->state_lock);
+	return 0;
+
+err_unlock:
+	mutex_unlock(&c->sb_lock);
+	up_write(&c->state_lock);
+err:
+	if (ca)
+		bch2_dev_free(ca);
+	bch2_free_super(&sb);
+	printbuf_exit(&label);
+	printbuf_exit(&errbuf);
+	return ret;
+err_late:
+	up_write(&c->state_lock);
+	ca = NULL;
+	goto err;
+}
+
+/* Hot add existing device to running filesystem: */
+int bch2_dev_online(struct bch_fs *c, const char *path)
+{
+	struct bch_opts opts = bch2_opts_empty();
+	struct bch_sb_handle sb = { NULL };
+	struct bch_dev *ca;
+	unsigned dev_idx;
+	int ret;
+
+	down_write(&c->state_lock);
+
+	ret = bch2_read_super(path, &opts, &sb);
+	if (ret) {
+		up_write(&c->state_lock);
+		return ret;
+	}
+
+	dev_idx = sb.sb->dev_idx;
+
+	ret = bch2_dev_in_fs(c->disk_sb.sb, sb.sb);
+	if (ret) {
+		bch_err_msg(c, ret, "bringing %s online", path);
+		goto err;
+	}
+
+	ret = bch2_dev_attach_bdev(c, &sb);
+	if (ret)
+		goto err;
+
+	ca = bch_dev_locked(c, dev_idx);
+
+	ret = bch2_trans_mark_dev_sb(c, ca);
+	if (ret) {
+		bch_err_msg(c, ret, "bringing %s online: error from bch2_trans_mark_dev_sb", path);
+		goto err;
+	}
+
+	if (ca->mi.state == BCH_MEMBER_STATE_rw)
+		__bch2_dev_read_write(c, ca);
+
+	if (!ca->mi.freespace_initialized) {
+		ret = bch2_dev_freespace_init(c, ca, 0, ca->mi.nbuckets);
+		bch_err_msg(ca, ret, "initializing free space");
+		if (ret)
+			goto err;
+	}
+
+	if (!ca->journal.nr) {
+		ret = bch2_dev_journal_alloc(ca);
+		bch_err_msg(ca, ret, "allocating journal");
+		if (ret)
+			goto err;
+	}
+
+	mutex_lock(&c->sb_lock);
+	bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx)->last_mount =
+		cpu_to_le64(ktime_get_real_seconds());
+	bch2_write_super(c);
+	mutex_unlock(&c->sb_lock);
+
+	up_write(&c->state_lock);
+	return 0;
+err:
+	up_write(&c->state_lock);
+	bch2_free_super(&sb);
+	return ret;
+}
+
+int bch2_dev_offline(struct bch_fs *c, struct bch_dev *ca, int flags)
+{
+	down_write(&c->state_lock);
+
+	if (!bch2_dev_is_online(ca)) {
+		bch_err(ca, "Already offline");
+		up_write(&c->state_lock);
+		return 0;
+	}
+
+	if (!bch2_dev_state_allowed(c, ca, BCH_MEMBER_STATE_failed, flags)) {
+		bch_err(ca, "Cannot offline required disk");
+		up_write(&c->state_lock);
+		return -BCH_ERR_device_state_not_allowed;
+	}
+
+	__bch2_dev_offline(c, ca);
+
+	up_write(&c->state_lock);
+	return 0;
+}
+
+int bch2_dev_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
+{
+	struct bch_member *m;
+	u64 old_nbuckets;
+	int ret = 0;
+
+	down_write(&c->state_lock);
+	old_nbuckets = ca->mi.nbuckets;
+
+	if (nbuckets < ca->mi.nbuckets) {
+		bch_err(ca, "Cannot shrink yet");
+		ret = -EINVAL;
+		goto err;
+	}
+
+	if (bch2_dev_is_online(ca) &&
+	    get_capacity(ca->disk_sb.bdev->bd_disk) <
+	    ca->mi.bucket_size * nbuckets) {
+		bch_err(ca, "New size larger than device");
+		ret = -BCH_ERR_device_size_too_small;
+		goto err;
+	}
+
+	ret = bch2_dev_buckets_resize(c, ca, nbuckets);
+	if (ret) {
+		bch_err_msg(ca, ret, "resizing buckets");
+		goto err;
+	}
+
+	ret = bch2_trans_mark_dev_sb(c, ca);
+	if (ret)
+		goto err;
+
+	mutex_lock(&c->sb_lock);
+	m = bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx);
+	m->nbuckets = cpu_to_le64(nbuckets);
+
+	bch2_write_super(c);
+	mutex_unlock(&c->sb_lock);
+
+	if (ca->mi.freespace_initialized) {
+		ret = bch2_dev_freespace_init(c, ca, old_nbuckets, nbuckets);
+		if (ret)
+			goto err;
+
+		/*
+		 * XXX: this is all wrong transactionally - we'll be able to do
+		 * this correctly after the disk space accounting rewrite
+		 */
+		ca->usage_base->d[BCH_DATA_free].buckets += nbuckets - old_nbuckets;
+	}
+
+	bch2_recalc_capacity(c);
+err:
+	up_write(&c->state_lock);
+	return ret;
+}
+
+/* return with ref on ca->ref: */
+struct bch_dev *bch2_dev_lookup(struct bch_fs *c, const char *name)
+{
+	struct bch_dev *ca;
+	unsigned i;
+
+	rcu_read_lock();
+	for_each_member_device_rcu(ca, c, i, NULL)
+		if (!strcmp(name, ca->name))
+			goto found;
+	ca = ERR_PTR(-BCH_ERR_ENOENT_dev_not_found);
+found:
+	rcu_read_unlock();
+
+	return ca;
+}
+
+/* Filesystem open: */
+
+struct bch_fs *bch2_fs_open(char * const *devices, unsigned nr_devices,
+			    struct bch_opts opts)
+{
+	DARRAY(struct bch_sb_handle) sbs = { 0 };
+	struct bch_fs *c = NULL;
+	struct bch_sb_handle *sb, *best = NULL;
+	struct printbuf errbuf = PRINTBUF;
+	int ret = 0;
+
+	if (!try_module_get(THIS_MODULE))
+		return ERR_PTR(-ENODEV);
+
+	if (!nr_devices) {
+		ret = -EINVAL;
+		goto err;
+	}
+
+	ret = darray_make_room(&sbs, nr_devices);
+	if (ret)
+		goto err;
+
+	for (unsigned i = 0; i < nr_devices; i++) {
+		struct bch_sb_handle sb = { NULL };
+
+		ret = bch2_read_super(devices[i], &opts, &sb);
+		if (ret)
+			goto err;
+
+		BUG_ON(darray_push(&sbs, sb));
+	}
+
+	darray_for_each(sbs, sb)
+		if (!best || le64_to_cpu(sb->sb->seq) > le64_to_cpu(best->sb->seq))
+			best = sb;
+
+	darray_for_each_reverse(sbs, sb) {
+		if (sb != best && !bch2_dev_exists(best->sb, sb->sb->dev_idx)) {
+			pr_info("%pg has been removed, skipping", sb->bdev);
+			bch2_free_super(sb);
+			darray_remove_item(&sbs, sb);
+			best -= best > sb;
+			continue;
+		}
+
+		ret = bch2_dev_in_fs(best->sb, sb->sb);
+		if (ret)
+			goto err_print;
+	}
+
+	c = bch2_fs_alloc(best->sb, opts);
+	ret = PTR_ERR_OR_ZERO(c);
+	if (ret)
+		goto err;
+
+	down_write(&c->state_lock);
+	darray_for_each(sbs, sb) {
+		ret = bch2_dev_attach_bdev(c, sb);
+		if (ret) {
+			up_write(&c->state_lock);
+			goto err;
+		}
+	}
+	up_write(&c->state_lock);
+
+	if (!bch2_fs_may_start(c)) {
+		ret = -BCH_ERR_insufficient_devices_to_start;
+		goto err_print;
+	}
+
+	if (!c->opts.nostart) {
+		ret = bch2_fs_start(c);
+		if (ret)
+			goto err;
+	}
+out:
+	darray_for_each(sbs, sb)
+		bch2_free_super(sb);
+	darray_exit(&sbs);
+	printbuf_exit(&errbuf);
+	module_put(THIS_MODULE);
+	return c;
+err_print:
+	pr_err("bch_fs_open err opening %s: %s",
+	       devices[0], bch2_err_str(ret));
+err:
+	if (!IS_ERR_OR_NULL(c))
+		bch2_fs_stop(c);
+	c = ERR_PTR(ret);
+	goto out;
+}
+
+/* Global interfaces/init */
+
+static void bcachefs_exit(void)
+{
+	bch2_debug_exit();
+	bch2_vfs_exit();
+	bch2_chardev_exit();
+	bch2_btree_key_cache_exit();
+	if (bcachefs_kset)
+		kset_unregister(bcachefs_kset);
+}
+
+static int __init bcachefs_init(void)
+{
+	bch2_bkey_pack_test();
+
+	if (!(bcachefs_kset = kset_create_and_add("bcachefs", NULL, fs_kobj)) ||
+	    bch2_btree_key_cache_init() ||
+	    bch2_chardev_init() ||
+	    bch2_vfs_init() ||
+	    bch2_debug_init())
+		goto err;
+
+	return 0;
+err:
+	bcachefs_exit();
+	return -ENOMEM;
+}
+
+#define BCH_DEBUG_PARAM(name, description)			\
+	bool bch2_##name;					\
+	module_param_named(name, bch2_##name, bool, 0644);	\
+	MODULE_PARM_DESC(name, description);
+BCH_DEBUG_PARAMS()
+#undef BCH_DEBUG_PARAM
+
+__maybe_unused
+static unsigned bch2_metadata_version = bcachefs_metadata_version_current;
+module_param_named(version, bch2_metadata_version, uint, 0400);
+
+module_exit(bcachefs_exit);
+module_init(bcachefs_init);