linux/fs/bcachefs/extents.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2010 Kent Overstreet <kent.overstreet@gmail.com>
 *
 * Code for managing the extent btree and dynamically updating the writeback
 * dirty sector count.
 */

#include "bcachefs.h"
#include "bkey_methods.h"
#include "btree_gc.h"
#include "btree_iter.h"
#include "buckets.h"
#include "checksum.h"
#include "debug.h"
#include "disk_groups.h"
#include "error.h"
#include "extents.h"
#include "inode.h"
#include "journal.h"
#include "replicas.h"
#include "super.h"
#include "super-io.h"
#include "trace.h"
#include "util.h"

static unsigned bch2_crc_field_size_max[] = {
	[BCH_EXTENT_ENTRY_crc32] = CRC32_SIZE_MAX,
	[BCH_EXTENT_ENTRY_crc64] = CRC64_SIZE_MAX,
	[BCH_EXTENT_ENTRY_crc128] = CRC128_SIZE_MAX,
};

static void bch2_extent_crc_pack(union bch_extent_crc *,
				 struct bch_extent_crc_unpacked,
				 enum bch_extent_entry_type);

static struct bch_dev_io_failures *dev_io_failures(struct bch_io_failures *f,
						   unsigned dev)
{
	struct bch_dev_io_failures *i;

	for (i = f->devs; i < f->devs + f->nr; i++)
		if (i->dev == dev)
			return i;

	return NULL;
}

void bch2_mark_io_failure(struct bch_io_failures *failed,
			  struct extent_ptr_decoded *p)
{
	struct bch_dev_io_failures *f = dev_io_failures(failed, p->ptr.dev);

	if (!f) {
		BUG_ON(failed->nr >= ARRAY_SIZE(failed->devs));

		f = &failed->devs[failed->nr++];
		f->dev		= p->ptr.dev;
		f->idx		= p->idx;
		f->nr_failed	= 1;
		f->nr_retries	= 0;
	} else if (p->idx != f->idx) {
		f->idx		= p->idx;
		f->nr_failed	= 1;
		f->nr_retries	= 0;
	} else {
		f->nr_failed++;
	}
}

/*
 * returns true if p1 is better than p2:
 */
static inline bool ptr_better(struct bch_fs *c,
			      const struct extent_ptr_decoded p1,
			      const struct extent_ptr_decoded p2)
{
	if (likely(!p1.idx && !p2.idx)) {
		struct bch_dev *dev1 = bch_dev_bkey_exists(c, p1.ptr.dev);
		struct bch_dev *dev2 = bch_dev_bkey_exists(c, p2.ptr.dev);

		u64 l1 = atomic64_read(&dev1->cur_latency[READ]);
		u64 l2 = atomic64_read(&dev2->cur_latency[READ]);

		/* Pick at random, biased in favor of the faster device: */

		return bch2_rand_range(l1 + l2) > l1;
	}

	if (force_reconstruct_read(c))
		return p1.idx > p2.idx;

	return p1.idx < p2.idx;
}

/*
 * This picks a non-stale pointer, preferably from a device other than @avoid.
 * Avoid can be NULL, meaning pick any. If there are no non-stale pointers to
 * other devices, it will still pick a pointer from avoid.
 */
int bch2_bkey_pick_read_device(struct bch_fs *c, struct bkey_s_c k,
			       struct bch_io_failures *failed,
			       struct extent_ptr_decoded *pick)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	const union bch_extent_entry *entry;
	struct extent_ptr_decoded p;
	struct bch_dev_io_failures *f;
	struct bch_dev *ca;
	int ret = 0;

	if (k.k->type == KEY_TYPE_error)
		return -EIO;

	bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
		ca = bch_dev_bkey_exists(c, p.ptr.dev);

		/*
		 * If there are any dirty pointers it's an error if we can't
		 * read:
		 */
		if (!ret && !p.ptr.cached)
			ret = -EIO;

		if (p.ptr.cached && ptr_stale(ca, &p.ptr))
			continue;

		f = failed ? dev_io_failures(failed, p.ptr.dev) : NULL;
		if (f)
			p.idx = f->nr_failed < f->nr_retries
				? f->idx
				: f->idx + 1;

		if (!p.idx &&
		    !bch2_dev_is_readable(ca))
			p.idx++;

		if (force_reconstruct_read(c) &&
		    !p.idx && p.has_ec)
			p.idx++;

		if (p.idx >= (unsigned) p.has_ec + 1)
			continue;

		if (ret > 0 && !ptr_better(c, p, *pick))
			continue;

		*pick = p;
		ret = 1;
	}

	return ret;
}

/* KEY_TYPE_btree_ptr: */

const char *bch2_btree_ptr_invalid(const struct bch_fs *c, struct bkey_s_c k)
{
	if (bkey_val_u64s(k.k) > BKEY_BTREE_PTR_VAL_U64s_MAX)
		return "value too big";

	return bch2_bkey_ptrs_invalid(c, k);
}

void bch2_btree_ptr_debugcheck(struct bch_fs *c, struct bkey_s_c k)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	const struct bch_extent_ptr *ptr;
	const char *err;
	char buf[160];
	struct bucket_mark mark;
	struct bch_dev *ca;

	if (!test_bit(BCH_FS_INITIAL_GC_DONE, &c->flags))
		return;

	if (!percpu_down_read_trylock(&c->mark_lock))
		return;

	bch2_fs_inconsistent_on(!test_bit(BCH_FS_REBUILD_REPLICAS, &c->flags) &&
		!bch2_bkey_replicas_marked(c, k, false), c,
		"btree key bad (replicas not marked in superblock):\n%s",
		(bch2_bkey_val_to_text(&PBUF(buf), c, k), buf));

	bkey_for_each_ptr(ptrs, ptr) {
		ca = bch_dev_bkey_exists(c, ptr->dev);

		mark = ptr_bucket_mark(ca, ptr);

		err = "stale";
		if (gen_after(mark.gen, ptr->gen))
			goto err;

		err = "inconsistent";
		if (mark.data_type != BCH_DATA_BTREE ||
		    mark.dirty_sectors < c->opts.btree_node_size)
			goto err;
	}
out:
	percpu_up_read(&c->mark_lock);
	return;
err:
	bch2_fs_inconsistent(c, "%s btree pointer %s: bucket %zi gen %i mark %08x",
		err, (bch2_bkey_val_to_text(&PBUF(buf), c, k), buf),
		PTR_BUCKET_NR(ca, ptr),
		mark.gen, (unsigned) mark.v.counter);
	goto out;
}

void bch2_btree_ptr_to_text(struct printbuf *out, struct bch_fs *c,
			    struct bkey_s_c k)
{
	bch2_bkey_ptrs_to_text(out, c, k);
}

/* KEY_TYPE_extent: */

const char *bch2_extent_invalid(const struct bch_fs *c, struct bkey_s_c k)
{
	return bch2_bkey_ptrs_invalid(c, k);
}

void bch2_extent_debugcheck(struct bch_fs *c, struct bkey_s_c k)
{
	struct bkey_s_c_extent e = bkey_s_c_to_extent(k);
	const union bch_extent_entry *entry;
	struct extent_ptr_decoded p;
	char buf[160];

	if (!test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags) ||
	    !test_bit(BCH_FS_INITIAL_GC_DONE, &c->flags))
		return;

	if (!percpu_down_read_trylock(&c->mark_lock))
		return;

	bch2_fs_inconsistent_on(!test_bit(BCH_FS_REBUILD_REPLICAS, &c->flags) &&
		!bch2_bkey_replicas_marked_locked(c, e.s_c, false), c,
		"extent key bad (replicas not marked in superblock):\n%s",
		(bch2_bkey_val_to_text(&PBUF(buf), c, e.s_c), buf));

	extent_for_each_ptr_decode(e, p, entry) {
		struct bch_dev *ca	= bch_dev_bkey_exists(c, p.ptr.dev);
		struct bucket_mark mark = ptr_bucket_mark(ca, &p.ptr);
		unsigned stale		= gen_after(mark.gen, p.ptr.gen);
		unsigned disk_sectors	= ptr_disk_sectors(p);
		unsigned mark_sectors	= p.ptr.cached
			? mark.cached_sectors
			: mark.dirty_sectors;

		bch2_fs_inconsistent_on(stale && !p.ptr.cached, c,
			"stale dirty pointer (ptr gen %u bucket %u",
			p.ptr.gen, mark.gen);

		bch2_fs_inconsistent_on(stale > 96, c,
			"key too stale: %i", stale);

		bch2_fs_inconsistent_on(!stale &&
			(mark.data_type != BCH_DATA_USER ||
			 mark_sectors < disk_sectors), c,
			"extent pointer not marked: %s:\n"
			"type %u sectors %u < %u",
			(bch2_bkey_val_to_text(&PBUF(buf), c, e.s_c), buf),
			mark.data_type,
			mark_sectors, disk_sectors);
	}

	percpu_up_read(&c->mark_lock);
}

void bch2_extent_to_text(struct printbuf *out, struct bch_fs *c,
			 struct bkey_s_c k)
{
	bch2_bkey_ptrs_to_text(out, c, k);
}

enum merge_result bch2_extent_merge(struct bch_fs *c,
				    struct bkey_s _l, struct bkey_s _r)
{
	struct bkey_s_extent l = bkey_s_to_extent(_l);
	struct bkey_s_extent r = bkey_s_to_extent(_r);
	union bch_extent_entry *en_l = l.v->start;
	union bch_extent_entry *en_r = r.v->start;
	struct bch_extent_crc_unpacked crc_l, crc_r;

	if (bkey_val_u64s(l.k) != bkey_val_u64s(r.k))
		return BCH_MERGE_NOMERGE;

	crc_l = bch2_extent_crc_unpack(l.k, NULL);

	extent_for_each_entry(l, en_l) {
		en_r = vstruct_idx(r.v, (u64 *) en_l - l.v->_data);

		if (extent_entry_type(en_l) != extent_entry_type(en_r))
			return BCH_MERGE_NOMERGE;

		switch (extent_entry_type(en_l)) {
		case BCH_EXTENT_ENTRY_ptr: {
			const struct bch_extent_ptr *lp = &en_l->ptr;
			const struct bch_extent_ptr *rp = &en_r->ptr;
			struct bch_dev *ca;

			if (lp->offset + crc_l.compressed_size != rp->offset ||
			    lp->dev			!= rp->dev ||
			    lp->gen			!= rp->gen)
				return BCH_MERGE_NOMERGE;

			/* We don't allow extents to straddle buckets: */
			ca = bch_dev_bkey_exists(c, lp->dev);

			if (PTR_BUCKET_NR(ca, lp) != PTR_BUCKET_NR(ca, rp))
				return BCH_MERGE_NOMERGE;

			break;
		}
		case BCH_EXTENT_ENTRY_stripe_ptr:
			if (en_l->stripe_ptr.block	!= en_r->stripe_ptr.block ||
			    en_l->stripe_ptr.idx	!= en_r->stripe_ptr.idx)
				return BCH_MERGE_NOMERGE;
			break;
		case BCH_EXTENT_ENTRY_crc32:
		case BCH_EXTENT_ENTRY_crc64:
		case BCH_EXTENT_ENTRY_crc128:
			crc_l = bch2_extent_crc_unpack(l.k, entry_to_crc(en_l));
			crc_r = bch2_extent_crc_unpack(r.k, entry_to_crc(en_r));

			if (crc_l.csum_type		!= crc_r.csum_type ||
			    crc_l.compression_type	!= crc_r.compression_type ||
			    crc_l.nonce			!= crc_r.nonce)
				return BCH_MERGE_NOMERGE;

			if (crc_l.offset + crc_l.live_size != crc_l.compressed_size ||
			    crc_r.offset)
				return BCH_MERGE_NOMERGE;

			if (!bch2_checksum_mergeable(crc_l.csum_type))
				return BCH_MERGE_NOMERGE;

			if (crc_l.compression_type)
				return BCH_MERGE_NOMERGE;

			if (crc_l.csum_type &&
			    crc_l.uncompressed_size +
			    crc_r.uncompressed_size > c->sb.encoded_extent_max)
				return BCH_MERGE_NOMERGE;

			if (crc_l.uncompressed_size + crc_r.uncompressed_size - 1 >
			    bch2_crc_field_size_max[extent_entry_type(en_l)])
				return BCH_MERGE_NOMERGE;

			break;
		default:
			return BCH_MERGE_NOMERGE;
		}
	}

	extent_for_each_entry(l, en_l) {
		struct bch_extent_crc_unpacked crc_l, crc_r;

		en_r = vstruct_idx(r.v, (u64 *) en_l - l.v->_data);

		if (!extent_entry_is_crc(en_l))
			continue;

		crc_l = bch2_extent_crc_unpack(l.k, entry_to_crc(en_l));
		crc_r = bch2_extent_crc_unpack(r.k, entry_to_crc(en_r));

		crc_l.csum = bch2_checksum_merge(crc_l.csum_type,
						 crc_l.csum,
						 crc_r.csum,
						 crc_r.uncompressed_size << 9);

		crc_l.uncompressed_size	+= crc_r.uncompressed_size;
		crc_l.compressed_size	+= crc_r.compressed_size;

		bch2_extent_crc_pack(entry_to_crc(en_l), crc_l,
				     extent_entry_type(en_l));
	}

	bch2_key_resize(l.k, l.k->size + r.k->size);

	return BCH_MERGE_MERGE;
}

/* KEY_TYPE_reservation: */

const char *bch2_reservation_invalid(const struct bch_fs *c, struct bkey_s_c k)
{
	struct bkey_s_c_reservation r = bkey_s_c_to_reservation(k);

	if (bkey_val_bytes(k.k) != sizeof(struct bch_reservation))
		return "incorrect value size";

	if (!r.v->nr_replicas || r.v->nr_replicas > BCH_REPLICAS_MAX)
		return "invalid nr_replicas";

	return NULL;
}

void bch2_reservation_to_text(struct printbuf *out, struct bch_fs *c,
			      struct bkey_s_c k)
{
	struct bkey_s_c_reservation r = bkey_s_c_to_reservation(k);

	pr_buf(out, "generation %u replicas %u",
	       le32_to_cpu(r.v->generation),
	       r.v->nr_replicas);
}

enum merge_result bch2_reservation_merge(struct bch_fs *c,
					 struct bkey_s _l, struct bkey_s _r)
{
	struct bkey_s_reservation l = bkey_s_to_reservation(_l);
	struct bkey_s_reservation r = bkey_s_to_reservation(_r);

	if (l.v->generation != r.v->generation ||
	    l.v->nr_replicas != r.v->nr_replicas)
		return BCH_MERGE_NOMERGE;

	if ((u64) l.k->size + r.k->size > KEY_SIZE_MAX) {
		bch2_key_resize(l.k, KEY_SIZE_MAX);
		bch2_cut_front_s(l.k->p, r.s);
		return BCH_MERGE_PARTIAL;
	}

	bch2_key_resize(l.k, l.k->size + r.k->size);

	return BCH_MERGE_MERGE;
}

/* Extent checksum entries: */

/* returns true if not equal */
static inline bool bch2_crc_unpacked_cmp(struct bch_extent_crc_unpacked l,
					 struct bch_extent_crc_unpacked r)
{
	return (l.csum_type		!= r.csum_type ||
		l.compression_type	!= r.compression_type ||
		l.compressed_size	!= r.compressed_size ||
		l.uncompressed_size	!= r.uncompressed_size ||
		l.offset		!= r.offset ||
		l.live_size		!= r.live_size ||
		l.nonce			!= r.nonce ||
		bch2_crc_cmp(l.csum, r.csum));
}

static inline bool can_narrow_crc(struct bch_extent_crc_unpacked u,
				  struct bch_extent_crc_unpacked n)
{
	return !u.compression_type &&
		u.csum_type &&
		u.uncompressed_size > u.live_size &&
		bch2_csum_type_is_encryption(u.csum_type) ==
		bch2_csum_type_is_encryption(n.csum_type);
}

bool bch2_can_narrow_extent_crcs(struct bkey_s_c k,
				 struct bch_extent_crc_unpacked n)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	struct bch_extent_crc_unpacked crc;
	const union bch_extent_entry *i;

	if (!n.csum_type)
		return false;

	bkey_for_each_crc(k.k, ptrs, crc, i)
		if (can_narrow_crc(crc, n))
			return true;

	return false;
}

/*
 * We're writing another replica for this extent, so while we've got the data in
 * memory we'll be computing a new checksum for the currently live data.
 *
 * If there are other replicas we aren't moving, and they are checksummed but
 * not compressed, we can modify them to point to only the data that is
 * currently live (so that readers won't have to bounce) while we've got the
 * checksum we need:
 */
bool bch2_bkey_narrow_crcs(struct bkey_i *k, struct bch_extent_crc_unpacked n)
{
	struct bkey_ptrs ptrs = bch2_bkey_ptrs(bkey_i_to_s(k));
	struct bch_extent_crc_unpacked u;
	struct extent_ptr_decoded p;
	union bch_extent_entry *i;
	bool ret = false;

	/* Find a checksum entry that covers only live data: */
	if (!n.csum_type) {
		bkey_for_each_crc(&k->k, ptrs, u, i)
			if (!u.compression_type &&
			    u.csum_type &&
			    u.live_size == u.uncompressed_size) {
				n = u;
				goto found;
			}
		return false;
	}
found:
	BUG_ON(n.compression_type);
	BUG_ON(n.offset);
	BUG_ON(n.live_size != k->k.size);

restart_narrow_pointers:
	ptrs = bch2_bkey_ptrs(bkey_i_to_s(k));

	bkey_for_each_ptr_decode(&k->k, ptrs, p, i)
		if (can_narrow_crc(p.crc, n)) {
			bch2_bkey_drop_ptr(bkey_i_to_s(k), &i->ptr);
			p.ptr.offset += p.crc.offset;
			p.crc = n;
			bch2_extent_ptr_decoded_append(k, &p);
			ret = true;
			goto restart_narrow_pointers;
		}

	return ret;
}

static void bch2_extent_crc_pack(union bch_extent_crc *dst,
				 struct bch_extent_crc_unpacked src,
				 enum bch_extent_entry_type type)
{
#define set_common_fields(_dst, _src)					\
		_dst.type		= 1 << type;			\
		_dst.csum_type		= _src.csum_type,		\
		_dst.compression_type	= _src.compression_type,	\
		_dst._compressed_size	= _src.compressed_size - 1,	\
		_dst._uncompressed_size	= _src.uncompressed_size - 1,	\
		_dst.offset		= _src.offset

	switch (type) {
	case BCH_EXTENT_ENTRY_crc32:
		set_common_fields(dst->crc32, src);
		dst->crc32.csum	 = *((__le32 *) &src.csum.lo);
		break;
	case BCH_EXTENT_ENTRY_crc64:
		set_common_fields(dst->crc64, src);
		dst->crc64.nonce	= src.nonce;
		dst->crc64.csum_lo	= src.csum.lo;
		dst->crc64.csum_hi	= *((__le16 *) &src.csum.hi);
		break;
	case BCH_EXTENT_ENTRY_crc128:
		set_common_fields(dst->crc128, src);
		dst->crc128.nonce	= src.nonce;
		dst->crc128.csum	= src.csum;
		break;
	default:
		BUG();
	}
#undef set_common_fields
}

void bch2_extent_crc_append(struct bkey_i *k,
			    struct bch_extent_crc_unpacked new)
{
	struct bkey_ptrs ptrs = bch2_bkey_ptrs(bkey_i_to_s(k));
	union bch_extent_crc *crc = (void *) ptrs.end;
	enum bch_extent_entry_type type;

	if (bch_crc_bytes[new.csum_type]	<= 4 &&
	    new.uncompressed_size - 1		<= CRC32_SIZE_MAX &&
	    new.nonce				<= CRC32_NONCE_MAX)
		type = BCH_EXTENT_ENTRY_crc32;
	else if (bch_crc_bytes[new.csum_type]	<= 10 &&
		   new.uncompressed_size - 1	<= CRC64_SIZE_MAX &&
		   new.nonce			<= CRC64_NONCE_MAX)
		type = BCH_EXTENT_ENTRY_crc64;
	else if (bch_crc_bytes[new.csum_type]	<= 16 &&
		   new.uncompressed_size - 1	<= CRC128_SIZE_MAX &&
		   new.nonce			<= CRC128_NONCE_MAX)
		type = BCH_EXTENT_ENTRY_crc128;
	else
		BUG();

	bch2_extent_crc_pack(crc, new, type);

	k->k.u64s += extent_entry_u64s(ptrs.end);

	EBUG_ON(bkey_val_u64s(&k->k) > BKEY_EXTENT_VAL_U64s_MAX);
}

/* Generic code for keys with pointers: */

unsigned bch2_bkey_nr_ptrs(struct bkey_s_c k)
{
	return bch2_bkey_devs(k).nr;
}

unsigned bch2_bkey_nr_ptrs_allocated(struct bkey_s_c k)
{
	return k.k->type == KEY_TYPE_reservation
		? bkey_s_c_to_reservation(k).v->nr_replicas
		: bch2_bkey_dirty_devs(k).nr;
}

unsigned bch2_bkey_nr_ptrs_fully_allocated(struct bkey_s_c k)
{
	unsigned ret = 0;

	if (k.k->type == KEY_TYPE_reservation) {
		ret = bkey_s_c_to_reservation(k).v->nr_replicas;
	} else {
		struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
		const union bch_extent_entry *entry;
		struct extent_ptr_decoded p;

		bkey_for_each_ptr_decode(k.k, ptrs, p, entry)
			ret += !p.ptr.cached &&
				p.crc.compression_type == BCH_COMPRESSION_TYPE_none;
	}

	return ret;
}

unsigned bch2_bkey_sectors_compressed(struct bkey_s_c k)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	const union bch_extent_entry *entry;
	struct extent_ptr_decoded p;
	unsigned ret = 0;

	bkey_for_each_ptr_decode(k.k, ptrs, p, entry)
		if (!p.ptr.cached &&
		    p.crc.compression_type != BCH_COMPRESSION_TYPE_none)
			ret += p.crc.compressed_size;

	return ret;
}

bool bch2_check_range_allocated(struct bch_fs *c, struct bpos pos, u64 size,
				unsigned nr_replicas)
{
	struct btree_trans trans;
	struct btree_iter *iter;
	struct bpos end = pos;
	struct bkey_s_c k;
	bool ret = true;
	int err;

	end.offset += size;

	bch2_trans_init(&trans, c, 0, 0);

	for_each_btree_key(&trans, iter, BTREE_ID_EXTENTS, pos,
			   BTREE_ITER_SLOTS, k, err) {
		if (bkey_cmp(bkey_start_pos(k.k), end) >= 0)
			break;

		if (nr_replicas > bch2_bkey_nr_ptrs_fully_allocated(k)) {
			ret = false;
			break;
		}
	}
	bch2_trans_exit(&trans);

	return ret;
}

static unsigned bch2_extent_ptr_durability(struct bch_fs *c,
					   struct extent_ptr_decoded p)
{
	unsigned durability = 0;
	struct bch_dev *ca;

	if (p.ptr.cached)
		return 0;

	ca = bch_dev_bkey_exists(c, p.ptr.dev);

	if (ca->mi.state != BCH_MEMBER_STATE_FAILED)
		durability = max_t(unsigned, durability, ca->mi.durability);

	if (p.has_ec) {
		struct stripe *s =
			genradix_ptr(&c->stripes[0], p.ec.idx);

		if (WARN_ON(!s))
			goto out;

		durability = max_t(unsigned, durability, s->nr_redundant);
	}
out:
	return durability;
}

unsigned bch2_bkey_durability(struct bch_fs *c, struct bkey_s_c k)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	const union bch_extent_entry *entry;
	struct extent_ptr_decoded p;
	unsigned durability = 0;

	bkey_for_each_ptr_decode(k.k, ptrs, p, entry)
		durability += bch2_extent_ptr_durability(c, p);

	return durability;
}

void bch2_bkey_mark_replicas_cached(struct bch_fs *c, struct bkey_s k,
				    unsigned target,
				    unsigned nr_desired_replicas)
{
	struct bkey_ptrs ptrs = bch2_bkey_ptrs(k);
	union bch_extent_entry *entry;
	struct extent_ptr_decoded p;
	int extra = bch2_bkey_durability(c, k.s_c) - nr_desired_replicas;

	if (target && extra > 0)
		bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
			int n = bch2_extent_ptr_durability(c, p);

			if (n && n <= extra &&
			    !bch2_dev_in_target(c, p.ptr.dev, target)) {
				entry->ptr.cached = true;
				extra -= n;
			}
		}

	if (extra > 0)
		bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
			int n = bch2_extent_ptr_durability(c, p);

			if (n && n <= extra) {
				entry->ptr.cached = true;
				extra -= n;
			}
		}
}

void bch2_bkey_append_ptr(struct bkey_i *k,
			  struct bch_extent_ptr ptr)
{
	EBUG_ON(bch2_bkey_has_device(bkey_i_to_s_c(k), ptr.dev));

	switch (k->k.type) {
	case KEY_TYPE_btree_ptr:
	case KEY_TYPE_extent:
		EBUG_ON(bkey_val_u64s(&k->k) >= BKEY_EXTENT_VAL_U64s_MAX);

		ptr.type = 1 << BCH_EXTENT_ENTRY_ptr;

		memcpy((void *) &k->v + bkey_val_bytes(&k->k),
		       &ptr,
		       sizeof(ptr));
		k->u64s++;
		break;
	default:
		BUG();
	}
}

static inline void __extent_entry_insert(struct bkey_i *k,
					 union bch_extent_entry *dst,
					 union bch_extent_entry *new)
{
	union bch_extent_entry *end = bkey_val_end(bkey_i_to_s(k));

	memmove_u64s_up_small((u64 *) dst + extent_entry_u64s(new),
			      dst, (u64 *) end - (u64 *) dst);
	k->k.u64s += extent_entry_u64s(new);
	memcpy_u64s_small(dst, new, extent_entry_u64s(new));
}

void bch2_extent_ptr_decoded_append(struct bkey_i *k,
				    struct extent_ptr_decoded *p)
{
	struct bkey_ptrs ptrs = bch2_bkey_ptrs(bkey_i_to_s(k));
	struct bch_extent_crc_unpacked crc =
		bch2_extent_crc_unpack(&k->k, NULL);
	union bch_extent_entry *pos;

	if (!bch2_crc_unpacked_cmp(crc, p->crc)) {
		pos = ptrs.start;
		goto found;
	}

	bkey_for_each_crc(&k->k, ptrs, crc, pos)
		if (!bch2_crc_unpacked_cmp(crc, p->crc)) {
			pos = extent_entry_next(pos);
			goto found;
		}

	bch2_extent_crc_append(k, p->crc);
	pos = bkey_val_end(bkey_i_to_s(k));
found:
	p->ptr.type = 1 << BCH_EXTENT_ENTRY_ptr;
	__extent_entry_insert(k, pos, to_entry(&p->ptr));

	if (p->has_ec) {
		p->ec.type = 1 << BCH_EXTENT_ENTRY_stripe_ptr;
		__extent_entry_insert(k, pos, to_entry(&p->ec));
	}
}

static union bch_extent_entry *extent_entry_prev(struct bkey_ptrs ptrs,
					  union bch_extent_entry *entry)
{
	union bch_extent_entry *i = ptrs.start;

	if (i == entry)
		return NULL;

	while (extent_entry_next(i) != entry)
		i = extent_entry_next(i);
	return i;
}

union bch_extent_entry *bch2_bkey_drop_ptr(struct bkey_s k,
					   struct bch_extent_ptr *ptr)
{
	struct bkey_ptrs ptrs = bch2_bkey_ptrs(k);
	union bch_extent_entry *dst, *src, *prev;
	bool drop_crc = true;

	EBUG_ON(ptr < &ptrs.start->ptr ||
		ptr >= &ptrs.end->ptr);
	EBUG_ON(ptr->type != 1 << BCH_EXTENT_ENTRY_ptr);

	src = extent_entry_next(to_entry(ptr));
	if (src != ptrs.end &&
	    !extent_entry_is_crc(src))
		drop_crc = false;

	dst = to_entry(ptr);
	while ((prev = extent_entry_prev(ptrs, dst))) {
		if (extent_entry_is_ptr(prev))
			break;

		if (extent_entry_is_crc(prev)) {
			if (drop_crc)
				dst = prev;
			break;
		}

		dst = prev;
	}

	memmove_u64s_down(dst, src,
			  (u64 *) ptrs.end - (u64 *) src);
	k.k->u64s -= (u64 *) src - (u64 *) dst;

	return dst;
}

void bch2_bkey_drop_device(struct bkey_s k, unsigned dev)
{
	struct bch_extent_ptr *ptr;

	bch2_bkey_drop_ptrs(k, ptr, ptr->dev == dev);
}

const struct bch_extent_ptr *
bch2_bkey_has_device(struct bkey_s_c k, unsigned dev)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	const struct bch_extent_ptr *ptr;

	bkey_for_each_ptr(ptrs, ptr)
		if (ptr->dev == dev)
			return ptr;

	return NULL;
}

bool bch2_bkey_has_target(struct bch_fs *c, struct bkey_s_c k, unsigned target)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	const struct bch_extent_ptr *ptr;

	bkey_for_each_ptr(ptrs, ptr)
		if (bch2_dev_in_target(c, ptr->dev, target) &&
		    (!ptr->cached ||
		     !ptr_stale(bch_dev_bkey_exists(c, ptr->dev), ptr)))
			return true;

	return false;
}

bool bch2_bkey_matches_ptr(struct bch_fs *c, struct bkey_s_c k,
			   struct bch_extent_ptr m, u64 offset)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	const union bch_extent_entry *entry;
	struct extent_ptr_decoded p;

	bkey_for_each_ptr_decode(k.k, ptrs, p, entry)
		if (p.ptr.dev	== m.dev &&
		    p.ptr.gen	== m.gen &&
		    (s64) p.ptr.offset + p.crc.offset - bkey_start_offset(k.k) ==
		    (s64) m.offset  - offset)
			return true;

	return false;
}

/*
 * bch_extent_normalize - clean up an extent, dropping stale pointers etc.
 *
 * Returns true if @k should be dropped entirely
 *
 * For existing keys, only called when btree nodes are being rewritten, not when
 * they're merely being compacted/resorted in memory.
 */
bool bch2_extent_normalize(struct bch_fs *c, struct bkey_s k)
{
	struct bch_extent_ptr *ptr;

	bch2_bkey_drop_ptrs(k, ptr,
		ptr->cached &&
		ptr_stale(bch_dev_bkey_exists(c, ptr->dev), ptr));

	/* will only happen if all pointers were cached: */
	if (!bch2_bkey_nr_ptrs(k.s_c))
		k.k->type = KEY_TYPE_discard;

	return bkey_whiteout(k.k);
}

void bch2_bkey_ptrs_to_text(struct printbuf *out, struct bch_fs *c,
			    struct bkey_s_c k)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	const union bch_extent_entry *entry;
	struct bch_extent_crc_unpacked crc;
	const struct bch_extent_ptr *ptr;
	const struct bch_extent_stripe_ptr *ec;
	struct bch_dev *ca;
	bool first = true;

	bkey_extent_entry_for_each(ptrs, entry) {
		if (!first)
			pr_buf(out, " ");

		switch (__extent_entry_type(entry)) {
		case BCH_EXTENT_ENTRY_ptr:
			ptr = entry_to_ptr(entry);
			ca = ptr->dev < c->sb.nr_devices && c->devs[ptr->dev]
				? bch_dev_bkey_exists(c, ptr->dev)
				: NULL;

			pr_buf(out, "ptr: %u:%llu gen %u%s%s", ptr->dev,
			       (u64) ptr->offset, ptr->gen,
			       ptr->cached ? " cached" : "",
			       ca && ptr_stale(ca, ptr)
			       ? " stale" : "");
			break;
		case BCH_EXTENT_ENTRY_crc32:
		case BCH_EXTENT_ENTRY_crc64:
		case BCH_EXTENT_ENTRY_crc128:
			crc = bch2_extent_crc_unpack(k.k, entry_to_crc(entry));

			pr_buf(out, "crc: c_size %u size %u offset %u nonce %u csum %u compress %u",
			       crc.compressed_size,
			       crc.uncompressed_size,
			       crc.offset, crc.nonce,
			       crc.csum_type,
			       crc.compression_type);
			break;
		case BCH_EXTENT_ENTRY_stripe_ptr:
			ec = &entry->stripe_ptr;

			pr_buf(out, "ec: idx %llu block %u",
			       (u64) ec->idx, ec->block);
			break;
		default:
			pr_buf(out, "(invalid extent entry %.16llx)", *((u64 *) entry));
			return;
		}

		first = false;
	}
}

static const char *extent_ptr_invalid(const struct bch_fs *c,
				      struct bkey_s_c k,
				      const struct bch_extent_ptr *ptr,
				      unsigned size_ondisk,
				      bool metadata)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	const struct bch_extent_ptr *ptr2;
	struct bch_dev *ca;

	if (!bch2_dev_exists2(c, ptr->dev))
		return "pointer to invalid device";

	ca = bch_dev_bkey_exists(c, ptr->dev);
	if (!ca)
		return "pointer to invalid device";

	bkey_for_each_ptr(ptrs, ptr2)
		if (ptr != ptr2 && ptr->dev == ptr2->dev)
			return "multiple pointers to same device";

	if (ptr->offset + size_ondisk > bucket_to_sector(ca, ca->mi.nbuckets))
		return "offset past end of device";

	if (ptr->offset < bucket_to_sector(ca, ca->mi.first_bucket))
		return "offset before first bucket";

	if (bucket_remainder(ca, ptr->offset) +
	    size_ondisk > ca->mi.bucket_size)
		return "spans multiple buckets";

	return NULL;
}

const char *bch2_bkey_ptrs_invalid(const struct bch_fs *c, struct bkey_s_c k)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	const union bch_extent_entry *entry;
	struct bch_extent_crc_unpacked crc;
	unsigned size_ondisk = k.k->size;
	const char *reason;
	unsigned nonce = UINT_MAX;

	if (k.k->type == KEY_TYPE_btree_ptr)
		size_ondisk = c->opts.btree_node_size;

	bkey_extent_entry_for_each(ptrs, entry) {
		if (__extent_entry_type(entry) >= BCH_EXTENT_ENTRY_MAX)
			return "invalid extent entry type";

		if (k.k->type == KEY_TYPE_btree_ptr &&
		    !extent_entry_is_ptr(entry))
			return "has non ptr field";

		switch (extent_entry_type(entry)) {
		case BCH_EXTENT_ENTRY_ptr:
			reason = extent_ptr_invalid(c, k, &entry->ptr,
						    size_ondisk, false);
			if (reason)
				return reason;
			break;
		case BCH_EXTENT_ENTRY_crc32:
		case BCH_EXTENT_ENTRY_crc64:
		case BCH_EXTENT_ENTRY_crc128:
			crc = bch2_extent_crc_unpack(k.k, entry_to_crc(entry));

			if (crc.offset + crc.live_size >
			    crc.uncompressed_size)
				return "checksum offset + key size > uncompressed size";

			size_ondisk = crc.compressed_size;

			if (!bch2_checksum_type_valid(c, crc.csum_type))
				return "invalid checksum type";

			if (crc.compression_type >= BCH_COMPRESSION_TYPE_NR)
				return "invalid compression type";

			if (bch2_csum_type_is_encryption(crc.csum_type)) {
				if (nonce == UINT_MAX)
					nonce = crc.offset + crc.nonce;
				else if (nonce != crc.offset + crc.nonce)
					return "incorrect nonce";
			}
			break;
		case BCH_EXTENT_ENTRY_stripe_ptr:
			break;
		}
	}

	return NULL;
}

void bch2_ptr_swab(const struct bkey_format *f, struct bkey_packed *k)
{
	union bch_extent_entry *entry;
	u64 *d = (u64 *) bkeyp_val(f, k);
	unsigned i;

	for (i = 0; i < bkeyp_val_u64s(f, k); i++)
		d[i] = swab64(d[i]);

	for (entry = (union bch_extent_entry *) d;
	     entry < (union bch_extent_entry *) (d + bkeyp_val_u64s(f, k));
	     entry = extent_entry_next(entry)) {
		switch (extent_entry_type(entry)) {
		case BCH_EXTENT_ENTRY_ptr:
			break;
		case BCH_EXTENT_ENTRY_crc32:
			entry->crc32.csum = swab32(entry->crc32.csum);
			break;
		case BCH_EXTENT_ENTRY_crc64:
			entry->crc64.csum_hi = swab16(entry->crc64.csum_hi);
			entry->crc64.csum_lo = swab64(entry->crc64.csum_lo);
			break;
		case BCH_EXTENT_ENTRY_crc128:
			entry->crc128.csum.hi = (__force __le64)
				swab64((__force u64) entry->crc128.csum.hi);
			entry->crc128.csum.lo = (__force __le64)
				swab64((__force u64) entry->crc128.csum.lo);
			break;
		case BCH_EXTENT_ENTRY_stripe_ptr:
			break;
		}
	}
}

/* Generic extent code: */

int bch2_cut_front_s(struct bpos where, struct bkey_s k)
{
	unsigned new_val_u64s = bkey_val_u64s(k.k);
	int val_u64s_delta;
	u64 sub;

	if (bkey_cmp(where, bkey_start_pos(k.k)) <= 0)
		return 0;

	EBUG_ON(bkey_cmp(where, k.k->p) > 0);

	sub = where.offset - bkey_start_offset(k.k);

	k.k->size -= sub;

	if (!k.k->size) {
		k.k->type = KEY_TYPE_deleted;
		new_val_u64s = 0;
	}

	switch (k.k->type) {
	case KEY_TYPE_extent:
	case KEY_TYPE_reflink_v: {
		struct bkey_ptrs ptrs = bch2_bkey_ptrs(k);
		union bch_extent_entry *entry;
		bool seen_crc = false;

		bkey_extent_entry_for_each(ptrs, entry) {
			switch (extent_entry_type(entry)) {
			case BCH_EXTENT_ENTRY_ptr:
				if (!seen_crc)
					entry->ptr.offset += sub;
				break;
			case BCH_EXTENT_ENTRY_crc32:
				entry->crc32.offset += sub;
				break;
			case BCH_EXTENT_ENTRY_crc64:
				entry->crc64.offset += sub;
				break;
			case BCH_EXTENT_ENTRY_crc128:
				entry->crc128.offset += sub;
				break;
			case BCH_EXTENT_ENTRY_stripe_ptr:
				break;
			}

			if (extent_entry_is_crc(entry))
				seen_crc = true;
		}

		break;
	}
	case KEY_TYPE_reflink_p: {
		struct bkey_s_reflink_p p = bkey_s_to_reflink_p(k);

		le64_add_cpu(&p.v->idx, sub);
		break;
	}
	case KEY_TYPE_inline_data: {
		struct bkey_s_inline_data d = bkey_s_to_inline_data(k);

		sub = min_t(u64, sub << 9, bkey_val_bytes(d.k));

		memmove(d.v->data,
			d.v->data + sub,
			bkey_val_bytes(d.k) - sub);

		new_val_u64s -= sub >> 3;
		break;
	}
	}

	val_u64s_delta = bkey_val_u64s(k.k) - new_val_u64s;
	BUG_ON(val_u64s_delta < 0);

	set_bkey_val_u64s(k.k, new_val_u64s);
	memset(bkey_val_end(k), 0, val_u64s_delta * sizeof(u64));
	return -val_u64s_delta;
}

int bch2_cut_back_s(struct bpos where, struct bkey_s k)
{
	unsigned new_val_u64s = bkey_val_u64s(k.k);
	int val_u64s_delta;
	u64 len = 0;

	if (bkey_cmp(where, k.k->p) >= 0)
		return 0;

	EBUG_ON(bkey_cmp(where, bkey_start_pos(k.k)) < 0);

	len = where.offset - bkey_start_offset(k.k);

	k.k->p = where;
	k.k->size = len;

	if (!len) {
		k.k->type = KEY_TYPE_deleted;
		new_val_u64s = 0;
	}

	switch (k.k->type) {
	case KEY_TYPE_inline_data:
		new_val_u64s = min(new_val_u64s, k.k->size << 6);
		break;
	}

	val_u64s_delta = bkey_val_u64s(k.k) - new_val_u64s;
	BUG_ON(val_u64s_delta < 0);

	set_bkey_val_u64s(k.k, new_val_u64s);
	memset(bkey_val_end(k), 0, val_u64s_delta * sizeof(u64));
	return -val_u64s_delta;
}