// SPDX-License-Identifier: GPL-2.0
/*
 * Code for manipulating bucket marks for garbage collection.
 *
 * Copyright 2014 Datera, Inc.
 */

#include "bcachefs.h"

#include "alloc/accounting.h"
#include "alloc/background.h"
#include "alloc/backpointers.h"
#include "alloc/buckets.h"
#include "alloc/replicas.h"

#include "btree/bset.h"
#include "btree/check.h"
#include "btree/interior.h"
#include "btree/update.h"

#include "data/copygc.h"
#include "data/ec/trigger.h"
#include "data/extents.h"
#include "data/reconcile/trigger.h"
#include "data/reflink.h"

#include "fs/inode.h"

#include "init/dev.h"
#include "init/error.h"
#include "init/recovery.h"
#include "init/passes.h"

#include <linux/preempt.h>

void bch2_dev_usage_read_fast(struct bch_dev *ca, struct bch_dev_usage *usage)
{
	memset(usage, 0, sizeof(*usage));

	/*
	 * One sweep over the cpus instead of BCH_DATA_NR of them: each cpu's
	 * usage is read once while its cache lines are hot. (We don't use the
	 * full-struct reader here to avoid a bch_dev_usage_full sized temporary
	 * on the allocation hot path.)
	 */
	int cpu;
	for_each_possible_cpu(cpu) {
		struct bch_dev_usage_full *u = per_cpu_ptr(ca->usage, cpu);

		for (unsigned i = 0; i < BCH_DATA_NR; i++)
			usage->buckets[i] += u->d[i].buckets;
	}
}

void bch2_dev_usage_full_read_fast(struct bch_dev *ca, struct bch_dev_usage_full *usage)
{
	memset(usage, 0, sizeof(*usage));
	acc_u64s_percpu((u64 *) usage, (u64 __percpu *) ca->usage,
			sizeof(struct bch_dev_usage_full) / sizeof(u64));
}

static u64 reserve_factor(u64 r)
{
	return r + (round_up(r, (1 << RESERVE_FACTOR)) >> RESERVE_FACTOR);
}

static struct bch_fs_usage_short
__bch2_fs_usage_read_short(struct bch_fs *c)
{
	/*
	 * Sum the whole per-cpu struct in a single sweep (one cache line per
	 * cpu); sectors_available is summed into the throwaway and ignored.
	 */
	struct bch_fs_capacity_pcpu b = {};
	acc_u64s_percpu((u64 *) &b, (u64 __percpu *) c->capacity.pcpu,
			sizeof(b) / sizeof(u64));

	struct bch_fs_usage_short ret;
	ret.capacity	= c->capacity.capacity - b.usage.hidden;

	u64 data	= b.usage.data + b.usage.btree;
	u64 reserved	= b.usage.reserved + b.online_reserved;

	ret.used	= min(ret.capacity, data + reserve_factor(reserved));
	ret.free	= ret.capacity - ret.used;

	return ret;
}

struct bch_fs_usage_short
bch2_fs_usage_read_short(struct bch_fs *c)
{
	guard(percpu_read_noio)(&c->capacity.mark_lock);
	return __bch2_fs_usage_read_short(c);
}

__cold void bch2_dev_usage_to_text(struct printbuf *out,
			    struct bch_dev *ca,
			    struct bch_dev_usage_full *usage)
{
	if (out->nr_tabstops < 5) {
		printbuf_tabstops_reset(out);
		printbuf_tabstop_push(out, 12);
		printbuf_tabstop_push(out, 16);
		printbuf_tabstop_push(out, 16);
		printbuf_tabstop_push(out, 16);
		printbuf_tabstop_push(out, 16);
	}

	prt_printf(out, "\tbuckets\rsectors\rfragmented\r\n");

	for (unsigned i = 0; i < BCH_DATA_NR; i++) {
		bch2_prt_data_type(out, i);
		prt_printf(out, "\t%llu\r%llu\r%llu\r\n",
			   usage->d[i].buckets,
			   usage->d[i].sectors,
			   usage->d[i].fragmented);
	}

	prt_printf(out, "capacity\t%llu\r\n", ca->mi.nbuckets);
}

static int bucket_ref_update_err(struct btree_trans *trans, struct printbuf *buf,
				 struct bkey_s_c k, bool fatal, enum bch_sb_error_id id)
{
	struct bch_fs *c = trans->c;

	prt_printf(buf, "\nwhile marking ");
	bch2_bkey_val_to_text(buf, c, k);
	prt_newline(buf);

	bool print = __bch2_count_fsck_err(c, id, buf);

	int ret = bch2_run_explicit_recovery_pass(c, buf,
					BCH_RECOVERY_PASS_check_allocations, 0);

	if (fatal) {
		bch2_trans_updates_to_text(buf, trans);
		__bch2_inconsistent_error(c, buf);
		/*
		 * If we're in recovery, run_explicit_recovery_pass might give
		 * us an error code for rewinding recovery
		 */
		if (!ret)
			ret = bch_err_throw(c, bucket_ref_update);
	} else {
		/* Always ignore overwrite errors, so that deletion works */
		ret = 0;
	}

	if (print || fatal)
		bch2_print_str(c, KERN_ERR, buf->buf);
	return ret;
}

noinline __cold
int __bch2_bucket_ref_update(struct btree_trans *trans, struct bch_dev *ca,
			     struct bkey_s_c k,
			     const struct bch_extent_ptr *ptr,
			     s64 sectors, enum bch_data_type ptr_data_type,
			     u8 b_gen, u8 *bucket_data_type,
			     u32 *bucket_sectors)
{
	struct bch_fs *c = trans->c;
	size_t bucket_nr = PTR_BUCKET_NR(ca, ptr);
	CLASS(printbuf, buf)();
	bool inserting = sectors > 0;

	BUG_ON(!sectors);

	if (unlikely(gen_after(ptr->generation, b_gen))) {
		bch2_log_msg_start(c, &buf);
		prt_printf(&buf,
			"bucket %u:%zu gen %u data type %s: ptr gen %u newer than bucket gen",
			ptr->dev, bucket_nr, b_gen,
			bch2_data_type_str(*bucket_data_type ?: ptr_data_type),
			ptr->generation);

		return bucket_ref_update_err(trans, &buf, k, inserting,
					     BCH_FSCK_ERR_ptr_gen_newer_than_bucket_gen);
	}

	if (unlikely(gen_cmp(b_gen, ptr->generation) > BUCKET_GC_GEN_MAX)) {
		bch2_log_msg_start(c, &buf);
		prt_printf(&buf,
			"bucket %u:%zu gen %u data type %s: ptr gen %u too stale",
			ptr->dev, bucket_nr, b_gen,
			bch2_data_type_str(*bucket_data_type ?: ptr_data_type),
			ptr->generation);

		return bucket_ref_update_err(trans, &buf, k, inserting,
					     BCH_FSCK_ERR_ptr_too_stale);
	}

	if (b_gen != ptr->generation && ptr->cached) {
		if (ret_fsck_err_on(c->sb.compat & BIT_ULL(BCH_COMPAT_no_stale_ptrs),
				trans, stale_ptr_with_no_stale_ptrs_feature,
				"stale cached ptr, but have no_stale_ptrs feature\n%s",
				(bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
			guard(mutex_noio)(&c->sb_lock);
			c->disk_sb.sb->compat[0] &= ~cpu_to_le64(BIT_ULL(BCH_COMPAT_no_stale_ptrs));
			bch2_write_super(c);
		}
		return 1;
	}

	if (unlikely(b_gen != ptr->generation)) {
		bch2_log_msg_start(c, &buf);
		prt_printf(&buf,
			"bucket %u:%zu gen %u (mem gen %u) data type %s: stale dirty ptr (gen %u)",
			ptr->dev, bucket_nr, b_gen,
			bucket_gen_get(ca, bucket_nr),
			bch2_data_type_str(*bucket_data_type ?: ptr_data_type),
			ptr->generation);

		return bucket_ref_update_err(trans, &buf, k, inserting,
					     BCH_FSCK_ERR_stale_dirty_ptr);
	}

	if (unlikely(bucket_data_type_mismatch(*bucket_data_type, ptr_data_type))) {
		bch2_log_msg_start(c, &buf);
		prt_printf(&buf, "bucket %u:%zu gen %u different types of data in same bucket: %s, %s",
			   ptr->dev, bucket_nr, b_gen,
			   bch2_data_type_str(*bucket_data_type),
			   bch2_data_type_str(ptr_data_type));

		try(bucket_ref_update_err(trans, &buf, k, false,
					  BCH_FSCK_ERR_ptr_bucket_data_type_mismatch));
		*bucket_data_type = BCH_DATA_multiple;
	}

	if (unlikely((u64) *bucket_sectors + sectors > U32_MAX)) {
		bch2_log_msg_start(c, &buf);
		prt_printf(&buf,
			"bucket %u:%zu gen %u data type %s sector count overflow: %u + %lli > U32_MAX",
			ptr->dev, bucket_nr, b_gen,
			bch2_data_type_str(*bucket_data_type ?: ptr_data_type),
			*bucket_sectors, sectors);

		sectors = -*bucket_sectors;
		return bucket_ref_update_err(trans, &buf, k, inserting,
					    BCH_FSCK_ERR_bucket_sector_count_overflow);
	}

	*bucket_sectors += sectors;
	return 0;
}

void bch2_trans_account_disk_usage_change(struct btree_trans *trans)
{
	struct bch_fs *c = trans->c;

	lockdep_assert_held(&c->capacity.mark_lock.lock);

	u64 disk_res_sectors = trans->disk_res ? trans->disk_res->sectors : 0;
	static int warned_disk_usage = 0;
	bool warn = false;

	struct bch_fs_usage_base *src = &trans->fs_usage_delta;

	s64 added = src->btree + src->data + src->reserved;

	/*
	 * Not allowed to reduce sectors_available except by getting a
	 * reservation:
	 */
	s64 should_not_have_added = added - (s64) disk_res_sectors;
	if (unlikely(should_not_have_added > 0)) {
		u64 old, new;

		old = atomic64_read(&c->capacity.sectors_available);
		do {
			new = max_t(s64, 0, old - should_not_have_added);
		} while (!atomic64_try_cmpxchg(&c->capacity.sectors_available,
					       &old, new));

		added -= should_not_have_added;
		warn = true;
	}

	if (added > 0) {
		trans->disk_res->sectors -= added;
		this_cpu_sub(c->capacity.pcpu->online_reserved, added);
	}

	scoped_guard(preempt) {
		struct bch_fs_usage_base *dst = &this_cpu_ptr(c->capacity.pcpu)->usage;
		acc_u64s((u64 *) dst, (u64 *) src, sizeof(*src) / sizeof(u64));
	}

	if (unlikely(warn) && !xchg(&warned_disk_usage, 1))
		bch2_trans_inconsistent(trans,
					"disk usage increased %lli more than %llu sectors reserved)",
					should_not_have_added, disk_res_sectors);
}

/* KEY_TYPE_extent: */

static int __mark_pointer(struct btree_trans *trans, struct bch_dev *ca,
			  struct bkey_s_c k,
			  const struct extent_ptr_decoded *p,
			  s64 sectors, enum bch_data_type ptr_data_type,
			  struct bch_alloc_v4 *a,
			  bool insert)
{
	u32 *dst_sectors = p->has_ec	? &a->stripe_sectors :
		!p->ptr.cached		? &a->dirty_sectors :
					  &a->cached_sectors;
	try(bch2_bucket_ref_update(trans, ca, k, &p->ptr, sectors, ptr_data_type,
				   a->generation, &a->data_type, dst_sectors));

	if (insert)
		alloc_data_type_set(a, ptr_data_type);
	return 0;
}

static noinline int
trigger_pointer_dev_missing(struct btree_trans *trans,
			    struct bkey_s_c k, unsigned dev,
			    bool insert)
{
	struct bch_fs *c = trans->c;
	int ret = insert
		? bch_err_throw(c, trigger_pointer)
		: 0;

	CLASS(bch_log_msg_ratelimited, msg)(c);
	prt_printf(&msg.m, "Error while %s key:\n", insert ? "inserting" : "deleting");
	ret = bch2_dev_missing_bkey_msg(c, k, dev, &msg.m);
	return ret;
}

static int bch2_trigger_pointer(struct btree_trans *trans,
			enum btree_id btree_id, unsigned level,
			struct bkey_s_c k, struct extent_ptr_decoded p,
			const union bch_extent_entry *entry,
			s64 *sectors,
			enum btree_iter_update_trigger_flags flags)
{
	struct bch_fs *c = trans->c;
	bool insert = !(flags & BTREE_TRIGGER_overwrite);

	struct bkey_i_backpointer bp;
	bch2_extent_ptr_to_bp(c, btree_id, level, k, p, entry, &bp);

	*sectors = insert ? bp.v.bucket_len : -(s64) bp.v.bucket_len;

	if (unlikely(p.ptr.dev == BCH_SB_MEMBER_INVALID)) {
		if ((flags & BTREE_TRIGGER_transactional) && p.has_ec) {
			if (!insert) {
				bp.k.type = KEY_TYPE_deleted;
				set_bkey_val_u64s(&bp.k, 0);
			}
			try(bch2_trans_update_buffered(trans, BTREE_ID_stripe_backpointers, &bp.k_i));
		}

		return 0;
	}

	CLASS(bch2_dev_tryget_noerror, ca)(c, p.ptr.dev);
	if (unlikely(!ca))
		return trigger_pointer_dev_missing(trans, k, p.ptr.dev, insert);

	struct bpos bucket = PTR_BUCKET_POS(ca, &p.ptr);
	if (!bucket_valid(ca, bucket.offset)) {
		if (insert) {
			bch2_dev_bucket_missing(ca, bucket.offset);
			return bch_err_throw(c, trigger_pointer);
		}
		return 0;
	}

	if (flags & BTREE_TRIGGER_transactional) {
		struct bkey_i_alloc_v4 *a = errptr_try(bch2_trans_start_alloc_update(trans, bucket, 0));
		try(__mark_pointer(trans, ca, k, &p, *sectors, bp.v.data_type, &a->v, insert));
		try(bch2_bucket_backpointer_mod(trans, k, &bp, insert));
	}

	if (flags & BTREE_TRIGGER_gc) {
		struct bucket *g = gc_bucket(ca, bucket.offset);
		struct bch_alloc_v4 old, new;

		scoped_guard(bucket_lock, g) {
			old = new = bucket_m_to_alloc(*g);
			try(__mark_pointer(trans, ca, k, &p, *sectors, bp.v.data_type, &new, insert));
			alloc_to_bucket(g, new);
		}

		try(bch2_alloc_key_to_dev_counters(trans, ca, &old, &new, flags));
	}

	return 0;
}

/*
 * An extent's erasure-coded pointer references a stripe it's not part of: the
 * stripe is gone, or it exists but its block pointers don't match. Either way,
 * log it, count it as a repairable fsck error, and ask check_allocations to
 * recompute the stripe's block accounting from scratch. The caller then skips
 * this pointer's block accounting instead of going emergency read-only.
 */
static int mark_stripe_ptr_no_match(struct btree_trans *trans,
				    struct bkey_s_c k, u64 idx)
{
	struct bch_fs *c = trans->c;
	CLASS(bch_log_msg_ratelimited, msg)(c);

	prt_printf(&msg.m, "extent doesn't match stripe %llu, not updating stripe block accounting\n  while marking ",
		   idx);
	bch2_bkey_val_to_text(&msg.m, c, k);
	prt_newline(&msg.m);

	bch2_count_fsck_err(c, stripe_update_stale_stripe_ptr, &msg.m);

	return bch2_run_explicit_recovery_pass(c, &msg.m,
			BCH_RECOVERY_PASS_check_allocations, 0);
}

static int bch2_trigger_stripe_ptr(struct btree_trans *trans,
				struct bkey_s_c k,
				struct extent_ptr_decoded p,
				enum bch_data_type data_type,
				s64 sectors,
				enum btree_iter_update_trigger_flags flags)
{
	struct bch_fs *c = trans->c;

	if (flags & BTREE_TRIGGER_transactional) {
		struct bkey_i_stripe *s = bch2_bkey_get_mut_typed(trans,
							BTREE_ID_stripes, POS(0, p.ec.idx),
							BTREE_ITER_cached, stripe);
		int ret = PTR_ERR_OR_ZERO(s);
		if (ret && !bch2_err_matches(ret, ENOENT))
			return ret;

		/*
		 * The stripe is gone (ENOENT), or it exists but doesn't match
		 * this extent's pointer: either way the extent isn't part of
		 * the stripe, so skip its block accounting.
		 */
		if (ret || !bch2_ptr_matches_stripe(&s->v, p))
			return mark_stripe_ptr_no_match(trans, k, p.ec.idx);

		try(stripe_csum_type_check(c, &s->v));

		stripe_blockcount_set(&s->v, p.ec.block,
			stripe_blockcount_get(&s->v, p.ec.block) +
			sectors);

		struct disk_accounting_pos acc;
		memset(&acc, 0, sizeof(acc));
		acc.type = BCH_DISK_ACCOUNTING_replicas;
		bch2_bkey_to_replicas(c, &acc.replicas, bkey_i_to_s_c(&s->k_i));
		acc.replicas.data_type = data_type;
		return bch2_disk_accounting_mod(trans, &acc, &sectors, 1, false);
	}

	if (flags & BTREE_TRIGGER_gc) {
		struct gc_stripe *m = genradix_ptr_alloc(&c->ec.gc_stripes, p.ec.idx, GFP_KERNEL);
		if (!m) {
			bch_err(c, "error allocating memory for gc_stripes, idx %llu",
				(u64) p.ec.idx);
			return bch_err_throw(c, ENOMEM_mark_stripe_ptr);
		}

		gc_stripe_lock(m);

		if (!m->alive || !bch2_ptr_matches_stripe_m(m, p)) {
			gc_stripe_unlock(m);
			return mark_stripe_ptr_no_match(trans, k, p.ec.idx);
		}

		m->block_sectors[p.ec.block] += sectors;

		struct disk_accounting_pos acc;
		memset(&acc, 0, sizeof(acc));
		acc.type = BCH_DISK_ACCOUNTING_replicas;
		unsafe_memcpy(&acc.replicas, &m->r.e, replicas_entry_bytes(&m->r.e), "VLA");
		gc_stripe_unlock(m);

		acc.replicas.data_type = data_type;
		try(bch2_disk_accounting_mod(trans, &acc, &sectors, 1, true));
	}

	return 0;
}

static int __trigger_extent(struct btree_trans *trans,
			    enum btree_id btree_id, unsigned level,
			    struct bkey_s_c k,
			    enum btree_iter_update_trigger_flags flags)
{
	bool gc = flags & BTREE_TRIGGER_gc;
	bool insert = !(flags & BTREE_TRIGGER_overwrite);
	struct bch_fs *c = trans->c;
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	const union bch_extent_entry *entry;
	struct extent_ptr_decoded p;
	enum bch_data_type data_type = bkey_is_btree_ptr(k.k)
		? BCH_DATA_btree
		: BCH_DATA_user;

	s64 replicas_sectors[1] = { 0 };

	struct disk_accounting_pos acc_replicas_key;
	memset(&acc_replicas_key, 0, sizeof(acc_replicas_key));
	acc_replicas_key.type = BCH_DISK_ACCOUNTING_replicas;
	acc_replicas_key.replicas.data_type	= data_type;
	acc_replicas_key.replicas.nr_devs	= 0;
	acc_replicas_key.replicas.nr_required	= 1;

	unsigned cur_compression_type = 0;
	u64 compression_acct[3] = { 1, 0, 0 };

	bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
		s64 disk_sectors = 0;
		int ret = bch2_trigger_pointer(trans, btree_id, level, k, p, entry, &disk_sectors, flags);
		if (ret < 0)
			return ret;

		bool stale = ret > 0;

		if (p.ptr.cached && stale)
			continue;

		if (p.ptr.cached) {
			try(bch2_mod_dev_cached_sectors(trans, p.ptr.dev, disk_sectors, gc));
		} else if (!p.has_ec) {
			replicas_sectors[0] += disk_sectors;
			replicas_entry_add_dev(&acc_replicas_key.replicas, p.ptr.dev);
		} else {
			try(bch2_trigger_stripe_ptr(trans, k, p, data_type, disk_sectors, flags));

			/*
			 * There may be other dirty pointers in this extent, but
			 * if so they're not required for mounting if we have an
			 * erasure coded pointer in this extent:
			 */
			acc_replicas_key.replicas.nr_required = 0;
		}

		if (cur_compression_type &&
		    cur_compression_type != p.crc.compression_type) {
			if (!insert)
				bch2_u64s_neg(compression_acct, ARRAY_SIZE(compression_acct));

			try(bch2_disk_accounting_mod2(trans, gc, compression_acct,
						      compression, cur_compression_type));

			compression_acct[0] = 1;
			compression_acct[1] = 0;
			compression_acct[2] = 0;
		}

		cur_compression_type = p.crc.compression_type;
		if (p.crc.compression_type) {
			compression_acct[1] += p.crc.uncompressed_size;
			compression_acct[2] += p.crc.compressed_size;
		}
	}

	if (acc_replicas_key.replicas.nr_devs)
		try(bch2_disk_accounting_mod(trans, &acc_replicas_key, replicas_sectors, 1, gc));

	/*
	 * Per-(snapshot, btree) accounting: [nr_keys, key_bytes, external
	 * sectors]. KEY_TYPE_extent self-accounts its key here rather than
	 * through the generic bch2_trigger_snapshot_nr_keys() hook, folding it
	 * into the sectors emission it already does - one accounting delta on
	 * the data hot path instead of two. The gate is looser than the sectors
	 * one (no nr_devs): a pointerless extent still counts as a key.
	 */
	if (!level && k.k->p.snapshot) {
		s64 nr = insert ? 1 : -1;
		s64 v[3] = { nr, nr * (s64) bkey_bytes(k.k), replicas_sectors[0] };

		try(bch2_disk_accounting_mod2(trans, gc, v, snapshot,
				k.k->p.snapshot, btree_id));
	}

	if (cur_compression_type) {
		if (!insert)
			bch2_u64s_neg(compression_acct, ARRAY_SIZE(compression_acct));

		try(bch2_disk_accounting_mod2(trans, gc, compression_acct,
					      compression, cur_compression_type));
	}

	if (level) {
		const bool leaf_node = level == 1;
		s64 v[3] = {
			replicas_sectors[0],
			insert ? 1 : -1,
			!leaf_node ? (insert ? 1 : -1) : 0,
		};

		try(bch2_disk_accounting_mod2(trans, gc, v, btree, btree_id));
	} else {
		s64 v[3] = {
			insert ? 1 : -1,
			insert ? k.k->size : -((s64) k.k->size),
			replicas_sectors[0],
		};
		try(bch2_disk_accounting_mod2(trans, gc, v, inum, k.k->p.inode));
	}

	return 0;
}

int bch2_trigger_extent(struct btree_trans *trans, struct btree_trigger_op op)
{
	struct bkey_ptrs_c new_ptrs = bch2_bkey_ptrs_c(op.new.s_c);
	struct bkey_ptrs_c old_ptrs = bch2_bkey_ptrs_c(op.old);
	unsigned new_ptrs_bytes = (void *) new_ptrs.end - (void *) new_ptrs.start;
	unsigned old_ptrs_bytes = (void *) old_ptrs.end - (void *) old_ptrs.start;

	/* if pointers aren't changing - nothing to do: */
	if (new_ptrs_bytes == old_ptrs_bytes &&
	    !memcmp(new_ptrs.start,
		    old_ptrs.start,
		    new_ptrs_bytes))
		return 0;

	if (op.flags & (BTREE_TRIGGER_transactional|BTREE_TRIGGER_gc)) {
		if ((op.flags & BTREE_TRIGGER_transactional) &&
		    (op.flags & BTREE_TRIGGER_insert) &&
		    !(op.flags & BTREE_TRIGGER_set_needs_reconcile_done) &&
		    !op.level &&
		    op.new.k->type)
			try(bch2_extent_trigger_set_needs_reconcile(trans, &op));

		if (op.old.k->type)
			try(__trigger_extent(trans, op.btree, op.level, op.old,
					     op.flags & ~BTREE_TRIGGER_insert));

		if (op.new.k->type)
			try(__trigger_extent(trans, op.btree, op.level, op.new.s_c,
					     op.flags & ~BTREE_TRIGGER_overwrite));

		try(bch2_trigger_extent_reconcile(trans, op));
	}

	return 0;
}

/* KEY_TYPE_reservation */

static int __trigger_reservation(struct btree_trans *trans,
			enum btree_id btree_id, unsigned level, struct bkey_s_c k,
			enum btree_iter_update_trigger_flags flags)
{
	if (flags & (BTREE_TRIGGER_transactional|BTREE_TRIGGER_gc)) {
		bool gc = flags & BTREE_TRIGGER_gc;
		unsigned nr_replicas = bkey_s_c_to_reservation(k).v->nr_replicas;
		s64 sectors[1] = { k.k->size };

		if (flags & BTREE_TRIGGER_overwrite)
			sectors[0] = -sectors[0];

		try(bch2_disk_accounting_mod2(trans, gc, sectors,
				persistent_reserved, nr_replicas));

		/*
		 * Per-snapshot accounting. Reservations reserve nr_replicas
		 * copies of the space but carry no pointers, so they never fed
		 * the per-snapshot sectors counter (summed from extent pointers);
		 * count the reserved physical sectors here. Like KEY_TYPE_extent,
		 * reservations self-account their key count rather than going
		 * through bch2_trigger_snapshot_nr_keys(), folding it into this
		 * one emission.
		 */
		if (!level && k.k->p.snapshot) {
			s64 nr = (flags & BTREE_TRIGGER_overwrite) ? -1 : 1;
			s64 v[3] = { nr, nr * (s64) bkey_bytes(k.k),
				     sectors[0] * (s64) nr_replicas };

			try(bch2_disk_accounting_mod2(trans, gc, v,
					snapshot, k.k->p.snapshot, btree_id));
		}
	}

	return 0;
}

int bch2_trigger_reservation(struct btree_trans *trans, struct btree_trigger_op op)
{
	return trigger_run_overwrite_then_insert(__trigger_reservation, trans,
						 op.btree, op.level, op.old, op.new, op.flags);
}

/*
 * Generic per-snapshot key-count accounting.
 *
 * Runs from the trigger dispatch (run_one_trans_trigger, run_one_mem_trigger,
 * bch2_gc_mark_key) for every leaf key in a snapshot btree, counting keys and
 * their bkey_bytes() per (snapshot id, btree) so snapshot deletion can verify
 * a node is empty before splicing it out. Whiteouts (bkey_extent_whiteout)
 * don't count: they're exactly the set iteration treats as absent, so the
 * deletion scan never visits them. KEY_TYPE_extent and KEY_TYPE_reservation
 * self-account in their own triggers - folded into the sectors emission they
 * already do - so they are excluded here to avoid a redundant accounting delta
 * on the hot path.
 *
 * The delta is net: count(new) - count(old). The trans dispatch substitutes a
 * deleted key on whichever side isn't running, so net yields the correct
 * per-side delta there; the gc/mem dispatch runs it once with the real old and
 * new. Skipped in the atomic phase, which only applies already-staged deltas.
 */
static bool snapshot_key_counted(const struct bkey *k)
{
	return k->p.snapshot &&
		!bkey_extent_whiteout(k) &&
		k->type != KEY_TYPE_extent &&
		k->type != KEY_TYPE_reservation;
}

int bch2_trigger_snapshot_nr_keys(struct btree_trans *trans, struct btree_trigger_op op)
{
	if (op.level || (op.flags & BTREE_TRIGGER_atomic))
		return 0;

	bool new_counted = snapshot_key_counted(op.new.k);
	bool old_counted = snapshot_key_counted(op.old.k);

	s64 nr = (s64) new_counted - (s64) old_counted;
	s64 bytes = (new_counted ? (s64) bkey_bytes(op.new.k) : 0) -
		    (old_counted ? (s64) bkey_bytes(op.old.k) : 0);
	if (!nr && !bytes)
		return 0;

	/* [nr_keys, key_bytes, external_sectors]; extents/reservations emit sectors */
	s64 v[3] = { nr, bytes, 0 };
	return bch2_disk_accounting_mod2(trans, op.flags & BTREE_TRIGGER_gc, v,
					 snapshot, op.new.k->p.snapshot, op.btree);
}

/* Mark superblocks: */

static int __bch2_trans_mark_metadata_bucket(struct btree_trans *trans,
				    struct bch_dev *ca, u64 b,
				    enum bch_data_type type,
				    unsigned sectors)
{
	struct bch_fs *c = trans->c;
	CLASS(btree_iter_uninit, iter)(trans);
	int ret = 0;

	struct bkey_i_alloc_v4 *a =
		bch2_trans_start_alloc_update_noupdate(trans, &iter, POS(ca->dev_idx, b));
	if (IS_ERR(a))
		return PTR_ERR(a);

	if (a->v.data_type && type && a->v.data_type != type) {
		CLASS(bch_log_msg, msg)(c);
		prt_printf(&msg.m, "bucket %llu:%llu gen %u different types of data in same bucket: %s, %s\n"
			   "while marking %s\n",
			   iter.pos.inode, iter.pos.offset, a->v.generation,
			   bch2_data_type_str(a->v.data_type),
			   bch2_data_type_str(type),
			   bch2_data_type_str(type));

		bch2_count_fsck_err(c, bucket_metadata_type_mismatch, &msg.m);

		try(bch2_run_explicit_recovery_pass(c, &msg.m,
					BCH_RECOVERY_PASS_check_allocations, 0));

		return bch_err_throw(c, metadata_bucket_inconsistency);
	}

	if (a->v.data_type	!= type ||
	    a->v.dirty_sectors	!= sectors) {
		a->v.data_type		= type;
		a->v.dirty_sectors	= sectors;
		ret = bch2_trans_update(trans, &iter, &a->k_i, 0);
	}

	return ret;
}

static int bch2_mark_metadata_bucket(struct btree_trans *trans, struct bch_dev *ca,
			u64 b, enum bch_data_type data_type, unsigned sectors,
			enum btree_iter_update_trigger_flags flags)
{
	struct bch_fs *c = trans->c;

	struct bucket *g = gc_bucket(ca, b);
	if (bch2_fs_inconsistent_on(!g, c, "reference to invalid bucket on device %u when marking metadata type %s",
				    ca->dev_idx, bch2_data_type_str(data_type)))
		return bch_err_throw(c, metadata_bucket_inconsistency);

	struct bch_alloc_v4 old, new;

	scoped_guard(bucket_lock, g) {
		old = bucket_m_to_alloc(*g);

		if (bch2_fs_inconsistent_on(g->data_type &&
				g->data_type != data_type, c,
				"different types of data in same bucket: %s, %s",
				bch2_data_type_str(g->data_type),
				bch2_data_type_str(data_type)))
			return bch_err_throw(c, metadata_bucket_inconsistency);

		if (bch2_fs_inconsistent_on((u64) g->dirty_sectors + sectors > ca->mi.bucket_size, c,
				"bucket %u:%llu gen %u data type %s sector count overflow: %u + %u > bucket size",
				ca->dev_idx, b, g->generation,
				bch2_data_type_str(g->data_type ?: data_type),
				g->dirty_sectors, sectors))
			return bch_err_throw(c, metadata_bucket_inconsistency);

		g->data_type = data_type;
		g->dirty_sectors += sectors;
		new = bucket_m_to_alloc(*g);
	}

	return bch2_alloc_key_to_dev_counters(trans, ca, &old, &new, flags);
}

int bch2_trans_mark_metadata_bucket(struct btree_trans *trans,
			struct bch_dev *ca, u64 b,
			enum bch_data_type type, unsigned sectors,
			enum btree_iter_update_trigger_flags flags)
{
	BUG_ON(type != BCH_DATA_free &&
	       type != BCH_DATA_sb &&
	       type != BCH_DATA_journal);

	/*
	 * Backup superblock might be past the end of our normal usable space:
	 */
	if (b >= ca->mi.nbuckets)
		return 0;

	if (flags & BTREE_TRIGGER_gc)
		return bch2_mark_metadata_bucket(trans, ca, b, type, sectors, flags);
	else if (flags & BTREE_TRIGGER_transactional)
		return commit_do(trans, NULL, NULL, (unsigned) BCH_WATERMARK_btree,
				 __bch2_trans_mark_metadata_bucket(trans, ca, b, type, sectors));
	else
		BUG();
}

static int bch2_trans_mark_metadata_sectors(struct btree_trans *trans,
			struct bch_dev *ca, u64 start, u64 end,
			enum bch_data_type type, u64 *bucket, unsigned *bucket_sectors,
			enum btree_iter_update_trigger_flags flags)
{
	do {
		u64 b = sector_to_bucket(ca, start);
		unsigned sectors =
			min_t(u64, bucket_to_sector(ca, b + 1), end) - start;

		if (b != *bucket && *bucket_sectors) {
			try(bch2_trans_mark_metadata_bucket(trans, ca, *bucket,
							    type, *bucket_sectors, flags));

			*bucket_sectors = 0;
		}

		*bucket		= b;
		*bucket_sectors	+= sectors;
		start += sectors;
	} while (start < end);

	return 0;
}

static int __bch2_trans_mark_dev_sb(struct btree_trans *trans, struct bch_dev *ca,
			enum btree_iter_update_trigger_flags flags)
{
	struct bch_fs *c = trans->c;
	struct bch_sb_layout layout;

	scoped_guard(mutex_noio, &c->sb_lock)
		layout = ca->disk_sb.sb->layout;

	u64 bucket = 0;
	unsigned i, bucket_sectors = 0;

	for (i = 0; i < layout.nr_superblocks; i++) {
		u64 offset = le64_to_cpu(layout.sb_offset[i]);

		if (offset == BCH_SB_SECTOR)
			try(bch2_trans_mark_metadata_sectors(trans, ca,
						0, BCH_SB_SECTOR,
						BCH_DATA_sb, &bucket, &bucket_sectors, flags));

		try(bch2_trans_mark_metadata_sectors(trans, ca, offset,
				      offset + (1 << layout.sb_max_size_bits),
				      BCH_DATA_sb, &bucket, &bucket_sectors, flags));
	}

	if (bucket_sectors)
		try(bch2_trans_mark_metadata_bucket(trans, ca,
						    bucket, BCH_DATA_sb, bucket_sectors, flags));

	for (i = 0; i < ca->journal.nr; i++)
		try(bch2_trans_mark_metadata_bucket(trans, ca,
				ca->journal.buckets[i],
				BCH_DATA_journal, ca->mi.bucket_size, flags));

	return 0;
}

int bch2_trans_mark_dev_sb(struct bch_fs *c, struct bch_dev *ca,
			enum btree_iter_update_trigger_flags flags)
{
	CLASS(btree_trans, trans)(c);
	int ret = __bch2_trans_mark_dev_sb(trans, ca, flags);
	bch_err_fn(c, ret);
	return ret;
}

int bch2_trans_mark_dev_sbs_flags(struct bch_fs *c,
			enum btree_iter_update_trigger_flags flags)
{
	for_each_online_member(c, ca, BCH_DEV_READ_REF_trans_mark_dev_sbs) {
		/* We unconditionally call bch2_trans_mark_dev_sb() again for an
		 * extra bit of safety; it's harmless if it wasn't needed, and
		 * double allocating a superblock or journal bucket would be
		 * particularly painful
		 */

		int ret = bch2_dev_add_initialize(c, ca) ?:
			  bch2_trans_mark_dev_sb(c, ca, flags);
		if (ret) {
			enumerated_ref_put(&ca->io_ref[READ], BCH_DEV_READ_REF_trans_mark_dev_sbs);
			return ret;
		}
	}

	return 0;
}

int bch2_trans_mark_dev_sbs(struct bch_fs *c)
{
	return bch2_trans_mark_dev_sbs_flags(c, BTREE_TRIGGER_transactional);
}

bool bch2_is_superblock_bucket(struct bch_dev *ca, u64 b)
{
	struct bch_sb_layout *layout = &ca->disk_sb.sb->layout;
	u64 b_offset	= bucket_to_sector(ca, b);
	u64 b_end	= bucket_to_sector(ca, b + 1);
	unsigned i;

	if (!b)
		return true;

	for (i = 0; i < layout->nr_superblocks; i++) {
		u64 offset = le64_to_cpu(layout->sb_offset[i]);
		u64 end = offset + (1 << layout->sb_max_size_bits);

		if (!(offset >= b_end || end <= b_offset))
			return true;
	}

	for (i = 0; i < ca->journal.nr; i++)
		if (b == ca->journal.buckets[i])
			return true;

	return false;
}

/* Disk reservations: */

#define SECTORS_CACHE	1024

static int disk_reservation_recalc_sectors_available(struct bch_fs *c,
			struct disk_reservation *res,
			u64 sectors, enum bch_reservation_flags flags)
{
	guard(spinlock)(&c->capacity.sectors_available_lock);

	percpu_u64_set(&c->capacity.pcpu->sectors_available, 0);
	u64 sectors_available = avail_factor(__bch2_fs_usage_read_short(c).free);

	if (sectors_available && (flags & BCH_DISK_RESERVATION_PARTIAL))
		sectors = min(sectors, sectors_available);

	if (sectors <= sectors_available ||
	    (flags & BCH_DISK_RESERVATION_NOFAIL)) {
		atomic64_set(&c->capacity.sectors_available,
			     max_t(s64, 0, sectors_available - sectors));
		this_cpu_add(c->capacity.pcpu->online_reserved, sectors);
		res->sectors			+= sectors;
		return 0;
	} else {
		atomic64_set(&c->capacity.sectors_available, sectors_available);
		return bch_err_throw(c, ENOSPC_disk_reservation);
	}
}

int __bch2_disk_reservation_add(struct bch_fs *c, struct disk_reservation *res,
				u64 sectors, enum bch_reservation_flags flags)
{
	guard(preempt)();
	struct bch_fs_capacity_pcpu *pcpu = this_cpu_ptr(c->capacity.pcpu);

	if (unlikely(sectors > pcpu->sectors_available)) {
		u64 get, old = atomic64_read(&c->capacity.sectors_available);

		do {
			get = min((u64) sectors + SECTORS_CACHE, old);

			if (unlikely(get < sectors))
				return disk_reservation_recalc_sectors_available(c,
								res, sectors, flags);
		} while (!atomic64_try_cmpxchg(&c->capacity.sectors_available,
					       &old, old - get));

		pcpu->sectors_available		+= get;
	}

	pcpu->sectors_available		-= sectors;
	pcpu->online_reserved		+= sectors;
	res->sectors			+= sectors;
	return 0;
}

/* Startup/shutdown: */

void bch2_buckets_nouse_free(struct bch_fs *c)
{
	for_each_member_device(c, ca) {
		kvfree_rcu_mightsleep(ca->buckets_nouse);
		ca->buckets_nouse = NULL;
	}
}

int bch2_buckets_nouse_alloc(struct bch_fs *c)
{
	for_each_member_device(c, ca) {
		BUG_ON(ca->buckets_nouse);

		ca->buckets_nouse = bch2_kvmalloc(BITS_TO_LONGS(ca->mi.nbuckets) *
					    sizeof(unsigned long),
					    GFP_KERNEL|__GFP_ZERO);
		if (!ca->buckets_nouse)
			return bch_err_throw(c, ENOMEM_buckets_nouse);
	}

	return 0;
}

static void bucket_gens_free_rcu(struct rcu_head *rcu)
{
	struct bucket_gens *buckets =
		container_of(rcu, struct bucket_gens, rcu);

	kvfree(buckets);
}
DEFINE_FREE(bucket_gens_free, struct bucket_gens *, if (_T) call_rcu(&_T->rcu, bucket_gens_free_rcu));

int bch2_dev_buckets_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
{
	struct bucket_gens *bucket_gens __free(bucket_gens_free) = NULL, *old_bucket_gens = NULL;
	bool resize = ca->bucket_gens != NULL;

	if (resize)
		lockdep_assert_held(&c->state_lock);

	if (resize && ca->buckets_nouse)
		return bch_err_throw(c, no_resize_with_buckets_nouse);

	bucket_gens = bch2_kvmalloc(struct_size(bucket_gens, b, nbuckets),
				    GFP_KERNEL|__GFP_ZERO);
	if (!bucket_gens)
		return bch_err_throw(c, ENOMEM_bucket_gens);

	bucket_gens->first_bucket = ca->mi.first_bucket;
	bucket_gens->nbuckets	= nbuckets;
	bucket_gens->nbuckets_minus_first =
		bucket_gens->nbuckets - bucket_gens->first_bucket;

	old_bucket_gens = rcu_dereference_protected(ca->bucket_gens, 1);

	if (resize) {
		u64 copy = min(bucket_gens->nbuckets,
			       old_bucket_gens->nbuckets);
		memcpy(bucket_gens->b,
		       old_bucket_gens->b,
		       sizeof(bucket_gens->b[0]) * copy);
	}

	try(bch2_bucket_bitmap_resize(ca, &ca->bucket_backpointer_mismatch, ca->mi.nbuckets, nbuckets));
	try(bch2_bucket_bitmap_resize(ca, &ca->bucket_backpointer_empty, ca->mi.nbuckets, nbuckets));

	rcu_assign_pointer(ca->bucket_gens, bucket_gens);
	bucket_gens	= old_bucket_gens;
	nbuckets	= ca->mi.nbuckets;

	return 0;
}

void bch2_dev_buckets_free(struct bch_dev *ca)
{
	kvfree(ca->buckets_nouse);
	kvfree(rcu_dereference_protected(ca->bucket_gens, 1));
	free_percpu(ca->usage);
}

int bch2_dev_buckets_alloc(struct bch_fs *c, struct bch_dev *ca)
{
	ca->usage = alloc_percpu(struct bch_dev_usage_full);
	if (!ca->usage)
		return bch_err_throw(c, ENOMEM_usage_init);

	return bch2_dev_buckets_resize(c, ca, ca->mi.nbuckets);
}
