// 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 "alloc/buckets.h"
#include "alloc/disk_groups.h"

#include "btree/bkey_methods.h"
#include "btree/cache.h"
#include "btree/iter.h"
#include "btree/read.h"
#include "btree/update.h"

#include "data/checksum.h"
#include "data/compress.h"
#include "data/extents.h"
#include "data/reconcile/trigger.h"

#include "fs/inode.h"

#include "init/error.h"

#include "util/util.h"

#ifdef CONFIG_BCACHEFS_DEBUG
#include <linux/module.h>

static int bch2_force_read_device = -1;

module_param_named(force_read_device, bch2_force_read_device, int, 0644);
MODULE_PARM_DESC(force_read_device, "");
#endif

static const char * const bch2_extent_flags_strs[] = {
#define x(n, v)	[BCH_EXTENT_FLAG_##n] = #n,
	BCH_EXTENT_FLAGS()
#undef x
	NULL,
};

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);

__cold void bch2_io_failures_to_text(struct printbuf *out,
			      struct bch_fs *c,
			      struct bch_io_failures *failed)
{
	scoped_guard(printbuf_indent, out)
		darray_for_each(*failed, f) {
			bch2_printbuf_make_room(out, 1024);
			scoped_guard(rcu) {
				guard(printbuf_atomic)(out);
				struct bch_dev *ca = bch2_dev_rcu_noerror(c, f->dev);
				if (ca)
					prt_str(out, ca->name);
				else
					prt_printf(out, "(invalid device %u)", f->dev);
			}

			if (!f->csum_nr && !f->ec_errcode && !f->errcode)
				prt_str(out, " no error - confused");

			if (f->csum_nr)
				prt_printf(out, " checksum (%u)", f->csum_nr);
			if (f->errcode)
				prt_printf(out, " io: %s", bch2_err_str(f->errcode));
			if (f->ec_errcode)
				prt_printf(out, " ec reconstruct: %s", bch2_err_str(f->ec_errcode));
			prt_newline(out);
		}

	if (failed->ec_msg.pos) {
		prt_printf(out, "ec reconstruct:\n");
		guard(printbuf_indent)(out);
		prt_str(out, failed->ec_msg.buf);
	}
}

struct bch_dev_io_failures *bch2_dev_io_failures(struct bch_io_failures *f,
						 unsigned dev)
{
	return darray_find_p(*f, i, i->dev == dev);
}

struct bch_dev_io_failures *bch2_dev_io_failures_mut(struct bch_io_failures *failed,
						     unsigned dev)
{
	struct bch_dev_io_failures *f = bch2_dev_io_failures(failed, dev);
	if (!f) {
		BUG_ON(failed->nr >= ARRAY_SIZE(failed->data));

		f = &failed->data[failed->nr++];
		memset(f, 0, sizeof(*f));
		f->dev = dev;
	}

	return f;
}

void bch2_mark_io_failure(struct bch_io_failures *failed,
			  struct extent_ptr_decoded *p, int err)
{
	BUG_ON(!err);
	BUG_ON(bch2_err_matches(err, BCH_ERR_transaction_restart));

	struct bch_dev_io_failures *f = bch2_dev_io_failures_mut(failed, p->ptr.dev);

	if (p->do_ec_reconstruct)
		f->ec_errcode = err;
	else if (err == -BCH_ERR_data_read_retry_csum_err)
		f->csum_nr++;
	else
		f->errcode = err;
}

static inline u64 dev_latency(struct bch_dev *ca)
{
	return ca ? atomic64_read(&ca->cur_latency[READ]) : S64_MAX;
}

static inline int dev_failed(struct bch_dev *ca)
{
	return !ca || ca->mi.state == BCH_MEMBER_STATE_evacuating;
}

/*
 * returns true if p1 is better than p2:
 */
static inline bool ptr_better(struct bch_fs *c,
			      const struct extent_ptr_decoded p1,
			      u64 p1_latency,
			      const struct extent_ptr_decoded p2,
			      u64 p2_latency,
			      unsigned preferred_dev,
			      enum bch_read_flags flags)
{
	if (static_branch_unlikely(&bch2_force_reconstruct_read))
		return p1.do_ec_reconstruct > p2.do_ec_reconstruct;

	if (unlikely(p1.do_ec_reconstruct || p2.do_ec_reconstruct))
		return p1.do_ec_reconstruct < p2.do_ec_reconstruct;

	int delta = (int) p2.crc_retry_nr - (int) p1.crc_retry_nr;
	if (unlikely(delta))
		return delta > 0;

#ifdef CONFIG_BCACHEFS_DEBUG
	if (bch2_force_read_device >= 0) {
		delta = (p1.ptr.dev == bch2_force_read_device) -
			(p2.ptr.dev == bch2_force_read_device);
		if (delta)
			return delta > 0;
	}
#endif

	/* Prefer extents with checksums */
	delta = (int) !!(p1.crc.csum_type) -
		(int) !!(p2.crc.csum_type);
	if (unlikely(delta))
		return delta > 0;

	if (unlikely(flags & BCH_READ_soft_require_read_device)) {
		if (p1.ptr.dev == preferred_dev) {
			if (bch2_dev_rotational(c, p2.ptr.dev))
				return true;
			p1_latency /= 256;
		}
		if (p2.ptr.dev == preferred_dev) {
			if (bch2_dev_rotational(c, p1.ptr.dev))
				return false;
			p2_latency /= 256;
		}
	}

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

	return bch2_get_random_u64_below(p1_latency + p2_latency) > p1_latency;
}

/*
 * 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,
			       unsigned preferred_dev,
			       enum bch_read_flags flags)
{
	bool have_csum_errors = false, have_io_errors = false, have_missing_devs = false;
	bool have_dirty_ptrs = false, have_pick = false;

	if (k.k->type == KEY_TYPE_error)
		return bch_err_throw(c, key_type_error);

	rcu_read_lock();
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	const union bch_extent_entry *entry;
	struct extent_ptr_decoded p;
	u64 pick_latency;

	bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
		have_dirty_ptrs |= !p.ptr.cached;

		/*
		 * Unwritten extent: no need to actually read, treat it as a
		 * hole and return 0s:
		 */
		if (p.ptr.unwritten) {
			rcu_read_unlock();
			return 0;
		}

		/* Are we being asked to read from a specific device? */
		if ((flags & BCH_READ_hard_require_read_device) &&
		    p.ptr.dev != preferred_dev)
			continue;

		struct bch_dev *ca = bch2_dev_rcu_noerror(c, p.ptr.dev);

		if (unlikely(!ca && p.ptr.dev != BCH_SB_MEMBER_INVALID)) {
			rcu_read_unlock();
			try(bch2_dev_missing_bkey(c, k, p.ptr.dev));
			rcu_read_lock();
		}

		if (p.ptr.cached && (!ca || dev_ptr_stale_rcu(ca, &p.ptr)))
			continue;

		struct bch_dev_io_failures *f =
			unlikely(failed) ? bch2_dev_io_failures(failed, p.ptr.dev) : NULL;
		if (unlikely(f)) {
			p.crc_retry_nr	   = f->csum_nr;
			p.has_ec	  &= !f->ec_errcode;

			if (ca) {
				have_io_errors	|= f->errcode != 0;
				have_io_errors	|= f->ec_errcode;
			}
			have_csum_errors	|= f->csum_nr != 0;

			if (p.has_ec && (f->errcode || f->csum_nr))
				p.do_ec_reconstruct = true;
			else if (f->errcode ||
				 f->csum_nr > c->opts.checksum_err_retry_nr)
				continue;
		}

		have_missing_devs |= ca && !bch2_dev_is_online(ca);

		if (!ca || !bch2_dev_is_online(ca)) {
			if (!p.has_ec)
				continue;
			p.do_ec_reconstruct = true;
		}

		if (static_branch_unlikely(&bch2_force_reconstruct_read) && p.has_ec)
			p.do_ec_reconstruct = true;

		u64 p_latency = dev_latency(ca);
		/*
		 * Square the latencies, to bias more in favor of the faster
		 * device - we never want to stop issuing reads to the slower
		 * device altogether, so that we can update our latency numbers:
		 */
		p_latency *= p_latency;

		if (!have_pick ||
		    ptr_better(c,
			       p, p_latency,
			       *pick, pick_latency,
			       preferred_dev, flags)) {
			*pick = p;
			pick_latency = p_latency;
			have_pick = true;
		}
	}
	rcu_read_unlock();

	if (have_pick)
		return 1;
	if (!have_dirty_ptrs && !bkey_is_btree_ptr(k.k))
		return 0;
	if (have_missing_devs || !have_dirty_ptrs)
		return bch_err_throw(c, no_device_to_read_from);
	if (have_csum_errors)
		return bch_err_throw(c, data_read_csum_err);
	if (have_io_errors)
		return bch_err_throw(c, data_read_io_err);

	/*
	 * If we get here, we have pointers (bkey_ptrs_validate() ensures that),
	 * but they don't point to valid devices:
	 */
	return bch_err_throw(c, no_devices_valid);
}

/* KEY_TYPE_btree_ptr: */

int bch2_btree_ptr_validate(struct bch_fs *c, struct bkey_s_c k,
			    const struct bkey_validate_context *from)
{
	int ret = 0;

	bkey_fsck_err_on(bkey_val_u64s(k.k) > BCH_REPLICAS_MAX,
			 c, btree_ptr_val_too_big,
			 "value too big (%zu > %u)", bkey_val_u64s(k.k), BCH_REPLICAS_MAX);

	ret = bch2_bkey_ptrs_validate(c, k, from);
fsck_err:
	return ret;
}

__cold 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);
}

int bch2_btree_ptr_v2_validate(struct bch_fs *c, struct bkey_s_c k,
			       const struct bkey_validate_context *from)
{
	struct bkey_s_c_btree_ptr_v2 bp = bkey_s_c_to_btree_ptr_v2(k);
	int ret = 0;

	bkey_fsck_err_on(bkey_val_u64s(k.k) > BKEY_BTREE_PTR_VAL_U64s_MAX,
			 c, btree_ptr_v2_val_too_big,
			 "value too big (%zu > %zu)",
			 bkey_val_u64s(k.k), BKEY_BTREE_PTR_VAL_U64s_MAX);

	bkey_fsck_err_on(bpos_ge(bp.v->min_key, bp.k->p),
			 c, btree_ptr_v2_min_key_bad,
			 "min_key > key");

	if ((from->flags & BCH_VALIDATE_write) &&
	    c->sb.version_min >= bcachefs_metadata_version_btree_ptr_sectors_written)
		bkey_fsck_err_on(!bp.v->sectors_written,
				 c, btree_ptr_v2_written_0,
				 "sectors_written == 0");

	ret = bch2_bkey_ptrs_validate(c, k, from);
fsck_err:
	return ret;
}

__cold void bch2_btree_ptr_v2_to_text(struct printbuf *out, struct bch_fs *c,
			       struct bkey_s_c k)
{
	struct bkey_s_c_btree_ptr_v2 bp = bkey_s_c_to_btree_ptr_v2(k);

	prt_printf(out, "\nseq %llx written %u min_key %s",
	       le64_to_cpu(bp.v->seq),
	       le16_to_cpu(bp.v->sectors_written),
	       BTREE_PTR_RANGE_UPDATED(bp.v) ? "R " : "");

	bch2_bpos_to_text(out, bp.v->min_key);
	prt_printf(out, " ");
	bch2_bkey_ptrs_to_text(out, c, k);
}

void bch2_btree_ptr_v2_compat(enum btree_id btree_id, unsigned version,
			      unsigned big_endian, int write,
			      struct bkey_s k)
{
	struct bkey_s_btree_ptr_v2 bp = bkey_s_to_btree_ptr_v2(k);

	compat_bpos(0, btree_id, version, big_endian, write, &bp.v->min_key);

	if (version < bcachefs_metadata_version_inode_btree_change &&
	    btree_id_is_extents(btree_id) &&
	    !bkey_eq(bp.v->min_key, POS_MIN))
		bp.v->min_key = write
			? bpos_nosnap_predecessor(bp.v->min_key)
			: bpos_nosnap_successor(bp.v->min_key);
}

/* KEY_TYPE_extent: */

bool bch2_extent_merge(struct bch_fs *c, struct bkey_s l, struct bkey_s_c r)
{
	struct bkey_ptrs   l_ptrs = bch2_bkey_ptrs(l);
	struct bkey_ptrs_c r_ptrs = bch2_bkey_ptrs_c(r);
	union bch_extent_entry *en_l;
	const union bch_extent_entry *en_r;
	struct extent_ptr_decoded lp, rp;
	bool use_right_ptr;

	en_l = l_ptrs.start;
	en_r = r_ptrs.start;
	while (en_l < l_ptrs.end && en_r < r_ptrs.end) {
		if (extent_entry_type(en_l) != extent_entry_type(en_r))
			return false;

		en_l = extent_entry_next(c, en_l);
		en_r = extent_entry_next(c, en_r);
	}

	if (en_l < l_ptrs.end || en_r < r_ptrs.end)
		return false;

	en_l = l_ptrs.start;
	en_r = r_ptrs.start;
	lp.crc = bch2_extent_crc_unpack(l.k, NULL);
	rp.crc = bch2_extent_crc_unpack(r.k, NULL);

	guard(rcu)();

	while (__bkey_ptr_next_decode(l.k, l_ptrs.end, lp, en_l) &&
	       __bkey_ptr_next_decode(r.k, r_ptrs.end, rp, en_r)) {
		if (lp.ptr.offset + lp.crc.offset + lp.crc.live_size !=
		    rp.ptr.offset + rp.crc.offset ||
		    lp.ptr.dev			!= rp.ptr.dev ||
		    lp.ptr.gen			!= rp.ptr.gen ||
		    lp.ptr.unwritten		!= rp.ptr.unwritten ||
		    lp.has_ec			!= rp.has_ec)
			return false;

		/* Extents may not straddle buckets: */
		struct bch_dev *ca = bch2_dev_rcu_noerror(c, lp.ptr.dev);
		bool same_bucket = ca && PTR_BUCKET_NR(ca, &lp.ptr) == PTR_BUCKET_NR(ca, &rp.ptr);

		if (!same_bucket)
			return false;

		if (lp.has_ec			!= rp.has_ec ||
		    (lp.has_ec &&
		     (lp.ec.block		!= rp.ec.block ||
		      lp.ec.redundancy		!= rp.ec.redundancy ||
		      lp.ec.idx			!= rp.ec.idx)))
			return false;

		if (lp.crc.compression_type	!= rp.crc.compression_type ||
		    lp.crc.nonce		!= rp.crc.nonce)
			return false;

		if (lp.crc.offset + lp.crc.live_size + rp.crc.live_size <=
		    lp.crc.uncompressed_size) {
			/* can use left extent's crc entry */
		} else if (lp.crc.live_size <= rp.crc.offset) {
			/* can use right extent's crc entry */
		} else {
			/* check if checksums can be merged: */
			if (lp.crc.csum_type		!= rp.crc.csum_type ||
			    lp.crc.nonce		!= rp.crc.nonce ||
			    crc_is_compressed(lp.crc) ||
			    !bch2_checksum_mergeable(lp.crc.csum_type))
				return false;

			if (lp.crc.offset + lp.crc.live_size != lp.crc.compressed_size ||
			    rp.crc.offset)
				return false;

			if (lp.crc.csum_type &&
			    lp.crc.uncompressed_size +
			    rp.crc.uncompressed_size > (c->opts.encoded_extent_max >> 9))
				return false;
		}

		en_l = extent_entry_next(c, en_l);
		en_r = extent_entry_next(c, en_r);
	}

	en_l = l_ptrs.start;
	en_r = r_ptrs.start;
	while (en_l < l_ptrs.end && en_r < r_ptrs.end) {
		if (extent_entry_is_crc(en_l)) {
			struct bch_extent_crc_unpacked crc_l = bch2_extent_crc_unpack(l.k, entry_to_crc(en_l));
			struct bch_extent_crc_unpacked crc_r = bch2_extent_crc_unpack(r.k, entry_to_crc(en_r));

			if (crc_l.uncompressed_size + crc_r.uncompressed_size >
			    bch2_crc_field_size_max[extent_entry_type(en_l)])
				return false;
		}

		en_l = extent_entry_next(c, en_l);
		en_r = extent_entry_next(c, en_r);
	}

	use_right_ptr = false;
	en_l = l_ptrs.start;
	en_r = r_ptrs.start;
	while (en_l < l_ptrs.end) {
		if (extent_entry_type(en_l) == BCH_EXTENT_ENTRY_ptr &&
		    use_right_ptr)
			en_l->ptr = en_r->ptr;

		if (extent_entry_is_crc(en_l)) {
			struct bch_extent_crc_unpacked crc_l =
				bch2_extent_crc_unpack(l.k, entry_to_crc(en_l));
			struct bch_extent_crc_unpacked crc_r =
				bch2_extent_crc_unpack(r.k, entry_to_crc(en_r));

			use_right_ptr = false;

			if (crc_l.offset + crc_l.live_size + crc_r.live_size <=
			    crc_l.uncompressed_size) {
				/* can use left extent's crc entry */
			} else if (crc_l.live_size <= crc_r.offset) {
				/* can use right extent's crc entry */
				crc_r.offset -= crc_l.live_size;
				bch2_extent_crc_pack(entry_to_crc(en_l), crc_r,
						     extent_entry_type(en_l));
				use_right_ptr = true;
			} else {
				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));
			}
		}

		en_l = extent_entry_next(c, en_l);
		en_r = extent_entry_next(c, en_r);
	}

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

/* KEY_TYPE_reservation: */

int bch2_reservation_validate(struct bch_fs *c, struct bkey_s_c k,
			      const struct bkey_validate_context *from)
{
	struct bkey_s_c_reservation r = bkey_s_c_to_reservation(k);
	int ret = 0;

	bkey_fsck_err_on(!r.v->nr_replicas || r.v->nr_replicas > BCH_REPLICAS_MAX,
			 c, reservation_key_nr_replicas_invalid,
			 "invalid nr_replicas (%u)", r.v->nr_replicas);
fsck_err:
	return ret;
}

__cold 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);

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

bool bch2_reservation_merge(struct bch_fs *c, struct bkey_s _l, struct bkey_s_c _r)
{
	struct bkey_s_reservation l = bkey_s_to_reservation(_l);
	struct bkey_s_c_reservation r = bkey_s_c_to_reservation(_r);

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

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

/* 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 union bch_extent_entry *bkey_crc_find(const struct bch_fs *c, struct bkey_i *k,
					     struct bch_extent_crc_unpacked crc)
{
	struct bkey_ptrs ptrs = bch2_bkey_ptrs(bkey_i_to_s(k));
	struct bch_extent_crc_unpacked i;
	union bch_extent_entry *entry;

	bkey_for_each_crc(&k->k, ptrs, i, entry)
		if (!bch2_crc_unpacked_cmp(i, crc))
			return entry;
	return NULL;
}

/*
 * 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_crc(const struct bch_fs *c,
			  struct bkey_i *k,
			  struct bch_extent_crc_unpacked old,
			  struct bch_extent_crc_unpacked new)
{
	BUG_ON(crc_is_compressed(new));
	BUG_ON(new.offset);
	BUG_ON(new.uncompressed_size != new.live_size);

	union bch_extent_entry *old_e = bkey_crc_find(c, k, old);
	if (!old_e)
		return false;

	struct bkey_ptrs ptrs = bch2_bkey_ptrs(bkey_i_to_s(k));
	union bch_extent_entry *i;

	bkey_extent_entry_for_each_from(ptrs, i, extent_entry_next(c, old_e)) {
		if (extent_entry_is_crc(i))
			break;
		if (extent_entry_is_ptr(i))
			i->ptr.offset += old.offset;
	}

	bch2_extent_crc_pack(entry_to_crc(old_e), new, extent_entry_type(old_e));
	return true;
}

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

	switch (type) {
	case BCH_EXTENT_ENTRY_crc32:
		dst->crc32		= (struct bch_extent_crc32) {
			common_fields(src),
			.csum		= (u32 __force) *((__le32 *) &src.csum.lo),
		};
		break;
	case BCH_EXTENT_ENTRY_crc64:
		dst->crc64		= (struct bch_extent_crc64) {
			common_fields(src),
			.nonce		= src.nonce,
			.csum_lo	= (u64 __force) src.csum.lo,
			.csum_hi	= (u64 __force) *((__le16 *) &src.csum.hi),
		};
		break;
	case BCH_EXTENT_ENTRY_crc128:
		dst->crc128		= (struct bch_extent_crc128) {
			common_fields(src),
			.nonce		= src.nonce,
			.csum		= src.csum,
		};
		break;
	default:
		BUG();
	}
#undef set_common_fields
}

void bch2_extent_crc_append(const struct bch_fs *c,
			    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		<= 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	<= 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	<= 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(c, ptrs.end);

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

/* Generic code for keys with pointers: */

unsigned bch2_bkey_nr_dirty_ptrs(const struct bch_fs *c, struct bkey_s_c k)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	unsigned ret = 0;

	bkey_for_each_ptr(ptrs, ptr)
		ret += !ptr->cached && ptr->dev != BCH_SB_MEMBER_INVALID;
	return ret;
}

unsigned bch2_bkey_nr_ptrs_allocated(const struct bch_fs *c, struct bkey_s_c k)
{
	if (k.k->type == KEY_TYPE_reservation) {
		return bkey_s_c_to_reservation(k).v->nr_replicas;
	} else {
		unsigned ret = 0;
		struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);

		bkey_for_each_ptr(ptrs, ptr)
			ret += !ptr->cached;
		return ret;
	}
}

unsigned bch2_bkey_nr_ptrs_fully_allocated(const struct bch_fs *c, struct bkey_s_c k)
{
	if (k.k->type == KEY_TYPE_reservation) {
		return 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;
		unsigned ret = 0;

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

unsigned bch2_bkey_sectors_compressed(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 extent_ptr_decoded p;
	unsigned ret = 0;

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

	return ret;
}

bool bch2_bkey_is_incompressible(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;

	bkey_for_each_crc(k.k, ptrs, crc, entry)
		if (crc.compression_type == BCH_COMPRESSION_TYPE_incompressible)
			return true;
	return false;
}

void bch2_bkey_propagate_incompressible(const struct bch_fs *c, struct bkey_i *dst, struct bkey_s_c src)
{
	if (!bch2_bkey_is_incompressible(c, src))
		return;

	struct bkey_ptrs ptrs = bch2_bkey_ptrs(bkey_i_to_s(dst));
	union bch_extent_entry *entry;

	/*
	 * XXX: if some data actually is compressed, we want
	 * bch_extent_reconcile.wont_recompress_smaller
	 */

	bkey_extent_entry_for_each(ptrs, entry) {
		switch (extent_entry_type(entry)) {
		case BCH_EXTENT_ENTRY_crc32:
			if (entry->crc32.compression_type == BCH_COMPRESSION_TYPE_none)
				entry->crc32.compression_type = BCH_COMPRESSION_TYPE_incompressible;
			break;
		case BCH_EXTENT_ENTRY_crc64:
			if (entry->crc64.compression_type == BCH_COMPRESSION_TYPE_none)
				entry->crc64.compression_type = BCH_COMPRESSION_TYPE_incompressible;
			break;
		case BCH_EXTENT_ENTRY_crc128:
			if (entry->crc128.compression_type == BCH_COMPRESSION_TYPE_none)
				entry->crc128.compression_type = BCH_COMPRESSION_TYPE_incompressible;
			break;
		default:
			break;
		}
	}
}

unsigned bch2_bkey_replicas(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 = { 0 };
	unsigned replicas = 0;

	bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
		if (p.ptr.cached)
			continue;

		if (p.has_ec)
			replicas += p.ec.redundancy;

		replicas++;

	}

	return replicas;
}

unsigned bch2_dev_durability(struct bch_fs *c, unsigned dev)
{
	guard(rcu)();
	struct bch_dev *ca = bch2_dev_rcu_noerror(c, dev);

	return ca && ca->mi.state != BCH_MEMBER_STATE_evacuating
		? ca->mi.durability
		: 0;
}

static inline unsigned __extent_ptr_durability(struct bch_dev *ca, struct extent_ptr_decoded *p)
{
	if (p->ptr.cached)
		return 0;

	return p->has_ec
		? p->ec.redundancy + 1
		: ca->mi.durability;
}

int bch2_extent_ptr_desired_durability(struct btree_trans *trans, struct extent_ptr_decoded *p)
{
	guard(rcu)();
	struct bch_dev *ca = bch2_dev_rcu_noerror(trans->c, p->ptr.dev);

	return ca ? __extent_ptr_durability(ca, p) : 0;
}

static unsigned bch2_extent_ptr_durability_rcu(struct bch_fs *c, struct extent_ptr_decoded *p)
{
	struct bch_dev *ca = bch2_dev_rcu_noerror(c, p->ptr.dev);

	if (!ca || ca->mi.state == BCH_MEMBER_STATE_evacuating)
		return 0;

	return __extent_ptr_durability(ca, p);
}

int bch2_extent_ptr_durability(struct btree_trans *trans, struct extent_ptr_decoded *p)
{
	guard(rcu)();
	return bch2_extent_ptr_durability_rcu(trans->c, p);
}

int bch2_bkey_durability(struct btree_trans *trans, struct bkey_s_c k, struct bkey_durability *ret)
{
	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;

	*ret = (struct bkey_durability) {};

	bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
		if (p.ptr.dev == BCH_SB_MEMBER_INVALID)
			continue;

		int d = bch2_extent_ptr_durability(trans, &p);
		if (d < 0)
			return d;

		if (bch2_dev_idx_is_online(c, p.ptr.dev))
			ret->online += d;
		ret->total += d;
	}
	return 0;
}

struct bkey_durability bch2_btree_ptr_durability(struct bch_fs *c, struct bkey_s_c k)
{
	BUG_ON(!bkey_is_btree_ptr(k.k));

	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	const union bch_extent_entry *entry;
	struct extent_ptr_decoded p;
	struct bkey_durability ret = {};

	guard(rcu)();
	bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
		if (p.ptr.dev == BCH_SB_MEMBER_INVALID)
			continue;

		unsigned d = bch2_extent_ptr_durability_rcu(c, &p);

		if (test_bit(p.ptr.dev, c->devs_online.d))
			ret.online += d;
		ret.total += d;
	}
	return ret;
}

bool bch2_bkey_can_read(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 extent_ptr_decoded p;

	bkey_for_each_ptr_decode(k.k, ptrs, p, entry)
		if (!p.ptr.cached &&
		    (p.ptr.dev != BCH_SB_MEMBER_INVALID ||
		     p.has_ec))
			return true;

	return false;
}

static unsigned bch2_bkey_durability_safe(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;

	guard(rcu)();
	bkey_for_each_ptr_decode(k.k, ptrs, p, entry)
		if (p.ptr.dev < c->sb.nr_devices && c->devs[p.ptr.dev])
			durability += bch2_extent_ptr_durability_rcu(c, &p);
	return durability;
}

void bch2_bkey_extent_entry_drop_s(const struct bch_fs *c, struct bkey_s k, union bch_extent_entry *entry)
{
	union bch_extent_entry *end = bkey_val_end(k);
	union bch_extent_entry *next = extent_entry_next(c, entry);

	memmove_u64s(entry, next, (u64 *) end - (u64 *) next);
	k.k->u64s -= extent_entry_u64s(c, entry);
}

void bch2_bkey_extent_entry_drop(const struct bch_fs *c, struct bkey_i *k, union bch_extent_entry *entry)
{
	union bch_extent_entry *end = bkey_val_end(bkey_i_to_s(k));
	union bch_extent_entry *next = extent_entry_next(c, entry);

	memmove_u64s(entry, next, (u64 *) end - (u64 *) next);
	k->k.u64s -= extent_entry_u64s(c, entry);
}

static union bch_extent_entry *bkey_find_crc(const struct bch_fs *c, struct bkey_s k,
					     struct bch_extent_crc_unpacked crc)
{
	struct bkey_ptrs ptrs = bch2_bkey_ptrs(k);
	struct bch_extent_crc_unpacked i;
	union bch_extent_entry *entry;

	bkey_for_each_crc(k.k, ptrs, i, entry)
		if (!bch2_crc_unpacked_cmp(i, crc))
			return entry;

	return NULL;
}

void bch2_extent_ptr_decoded_append(const struct bch_fs *c, struct bkey_i *k,
				    struct extent_ptr_decoded *p)
{
	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 = bch2_bkey_ptrs(bkey_i_to_s(k)).start;
	} else if ((pos = bkey_find_crc(c, bkey_i_to_s(k), p->crc))) {
		pos = extent_entry_next(c, pos);
	} else {
		bch2_extent_crc_append(c, k, p->crc);
		pos = bkey_val_end(bkey_i_to_s(k));
	}

	p->ptr.type = 1 << BCH_EXTENT_ENTRY_ptr;
	__extent_entry_insert(c, k, pos, to_entry(&p->ptr));

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

static union bch_extent_entry *extent_entry_prev(const struct bch_fs *c, 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(c, i) != entry)
		i = extent_entry_next(c, i);
	return i;
}

/*
 * Returns pointer to the next entry after the one being dropped:
 */
void bch2_bkey_drop_ptr_noerror(const struct bch_fs *c, struct bkey_s k, struct bch_extent_ptr *ptr)
{
	struct bkey_ptrs ptrs = bch2_bkey_ptrs(k);
	union bch_extent_entry *entry = to_entry(ptr), *next;
	bool drop_crc = true;

	if (k.k->type == KEY_TYPE_stripe) {
		ptr->dev = BCH_SB_MEMBER_INVALID;
		return;
	}

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

	for (next = extent_entry_next(c, entry);
	     next != ptrs.end;
	     next = extent_entry_next(c, next)) {
		if (extent_entry_is_crc(next)) {
			break;
		} else if (extent_entry_is_ptr(next)) {
			drop_crc = false;
			break;
		}
	}

	extent_entry_drop(c, k, entry);

	while ((entry = extent_entry_prev(c, ptrs, entry))) {
		if (extent_entry_is_ptr(entry))
			break;

		if ((extent_entry_is_crc(entry) && drop_crc) ||
		    extent_entry_is_stripe_ptr(entry))
			extent_entry_drop(c, k, entry);
	}
}

void bch2_bkey_drop_ptr(const struct bch_fs *c, struct bkey_s k, struct bch_extent_ptr *ptr)
{
	if (k.k->type != KEY_TYPE_stripe) {
		struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k.s_c);
		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 == ptr->dev && p.has_ec) {
				ptr->dev = BCH_SB_MEMBER_INVALID;
				return;
			}
	}

	bch2_bkey_drop_ptr_noerror(c, k, ptr);
}

void bch2_bkey_drop_ptrs_mask(const struct bch_fs *c, struct bkey_i *k, unsigned ptrs)
{
	while (ptrs) {
		unsigned i = 0, drop = __fls(ptrs);

		bch2_bkey_drop_ptrs_noerror(bkey_i_to_s(k), p, entry, i++ == drop);
		ptrs  ^= 1U << drop;
	}
}

void bch2_bkey_drop_device_noerror(const struct bch_fs *c, struct bkey_s k, unsigned dev)
{
	bch2_bkey_drop_ptrs_noerror(k, p, entry, p.ptr.dev == dev);
}

void bch2_bkey_drop_device(const struct bch_fs *c, struct bkey_s k, unsigned dev)
{
	bch2_bkey_drop_ptrs(k, p, entry, p.ptr.dev == dev);
}

static void bch2_bkey_drop_ec(const struct bch_fs *c, struct bkey_i *k, unsigned dev)
{
	struct bkey_ptrs ptrs = bch2_bkey_ptrs(bkey_i_to_s(k));
	union bch_extent_entry *entry, *ec = NULL;

	bkey_extent_entry_for_each(ptrs, entry) {
		if (extent_entry_type(entry) == BCH_EXTENT_ENTRY_stripe_ptr)
			ec = entry;
		else if (extent_entry_type(entry) == BCH_EXTENT_ENTRY_ptr &&
			 entry->ptr.dev == dev) {
			bch2_bkey_extent_entry_drop(c, k, ec);
			return;
		}
	}
}

void bch2_bkey_drop_ec_mask(const struct bch_fs *c, struct bkey_i *k, unsigned mask)
{
	while (mask) {
		struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(bkey_i_to_s_c(k));
		unsigned ptr_bit = 1;
		bkey_for_each_ptr(ptrs, ptr) {
			if (mask & ptr_bit) {
				bch2_bkey_drop_ec(c, k, ptr->dev);
				mask &= ~ptr_bit;
				break;
			}
			ptr_bit <<= 1;
		}
	}
}

const struct bch_extent_ptr *bch2_bkey_has_device_c(const struct bch_fs *c, struct bkey_s_c k, unsigned dev)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);

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

	return NULL;
}

bool bch2_bkey_has_device_decode(const struct bch_fs *c, struct bkey_s_c k, unsigned dev,
				 struct extent_ptr_decoded *ret)
{
	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 == dev) {
			*ret = p;
			return true;
		}

	return false;
}

bool bch2_bkey_devs_rw(struct bch_fs *c, struct bkey_s_c k)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);

	guard(rcu)();
	bkey_for_each_ptr(ptrs, ptr) {
		struct bch_dev *ca = bch2_dev_rcu_noerror(c, ptr->dev);
		if (!ca || ca->mi.state != BCH_MEMBER_STATE_rw)
			return false;
	}

	return true;
}

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);
	struct bch_dev *ca;

	guard(rcu)();
	bkey_for_each_ptr(ptrs, ptr)
		if (bch2_dev_in_target_rcu(c, ptr->dev, target) &&
		    (ca = bch2_dev_rcu_noerror(c, ptr->dev)) &&
		    (!ptr->cached ||
		     !dev_ptr_stale_rcu(ca, ptr)))
			return true;

	return false;
}

bool bch2_bkey_in_target(struct bch_fs *c, struct bkey_s_c k, unsigned target)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);

	guard(rcu)();
	bkey_for_each_ptr(ptrs, ptr)
		if (!bch2_dev_in_target_rcu(c, ptr->dev, target))
			return false;

	return true;
}

bool bch2_bkey_has_dev_bad_or_evacuating(struct bch_fs *c, struct bkey_s_c k)
{
	guard(rcu)();
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	bkey_for_each_ptr(ptrs, ptr)
		if (bch2_dev_bad_or_evacuating_rcu(c, ptr->dev))
			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;
}

bool bch2_bkey_ptrs_match(struct bkey_s_c k1, struct extent_ptr_decoded p1,
			  struct bkey_s_c k2, struct extent_ptr_decoded p2)
{
	return ((p1.ptr.dev		== p2.ptr.dev ||
		 (p1.has_ec && p2.has_ec &&
		  p1.ec.idx		== p2.ec.idx &&
		  p1.ec.block		== p2.ec.block)) &&

		p1.ptr.gen		== p2.ptr.gen &&

		/*
		 * This checks that the two pointers point
		 * to the same region on disk - adjusting
		 * for the difference in where the extents
		 * start, since one may have been trimmed:
		 */
		(s64) p1.ptr.offset + p1.crc.offset - bkey_start_offset(k1.k) ==
		(s64) p2.ptr.offset + p2.crc.offset - bkey_start_offset(k2.k) &&

		/*
		 * This additionally checks that the
		 * extents overlap on disk, since the
		 * previous check may trigger spuriously
		 * when one extent is immediately partially
		 * overwritten with another extent (so that
		 * on disk they are adjacent) and
		 * compression is in use:
		 */
		((p1.ptr.offset >= p2.ptr.offset &&
		  p1.ptr.offset  < p2.ptr.offset + p2.crc.compressed_size) ||
		 (p2.ptr.offset >= p1.ptr.offset &&
		  p2.ptr.offset  < p1.ptr.offset + p1.crc.compressed_size)));
}

/*
 * Returns true if two extents refer to the same data:
 */
bool bch2_extents_match(const struct bch_fs *c, struct bkey_s_c k1, struct bkey_s_c k2)
{
	if (k1.k->type != k2.k->type)
		return false;

	if (bkey_extent_is_direct_data(k1.k)) {
		struct bkey_ptrs_c ptrs1 = bch2_bkey_ptrs_c(k1);
		struct bkey_ptrs_c ptrs2 = bch2_bkey_ptrs_c(k2);
		const union bch_extent_entry *entry1, *entry2;
		struct extent_ptr_decoded p1, p2;

		if (bkey_extent_is_unwritten(c, k1) != bkey_extent_is_unwritten(c, k2))
			return false;

		bkey_for_each_ptr_decode(k1.k, ptrs1, p1, entry1)
			bkey_for_each_ptr_decode(k2.k, ptrs2, p2, entry2)
				if (bch2_bkey_ptrs_match(k1, p1, k2, p2))
					return true;

		return false;
	} else {
		/* KEY_TYPE_deleted, etc. */
		return true;
	}
}

struct bch_extent_ptr *
bch2_extent_has_ptr(const struct bch_fs *c, struct bkey_s_c k1,
		    struct extent_ptr_decoded p1, struct bkey_s k2)
{
	struct bkey_ptrs ptrs2 = bch2_bkey_ptrs(k2);
	union bch_extent_entry *entry2;
	struct extent_ptr_decoded p2;

	bkey_for_each_ptr_decode(k2.k, ptrs2, p2, entry2)
		if (p1.ptr.dev		== p2.ptr.dev &&
		    p1.ptr.gen		== p2.ptr.gen &&
		    (s64) p1.ptr.offset + p1.crc.offset - bkey_start_offset(k1.k) ==
		    (s64) p2.ptr.offset + p2.crc.offset - bkey_start_offset(k2.k))
			return &entry2->ptr;

	return NULL;
}

static bool drop_cached_pointer_trace(struct bch_fs *c, struct bkey_s k,
				      struct bch_extent_ptr *ptr, const char *msg)
{
	event_add_trace(c, cached_ptr_drop, k.k->size, buf, ({
		prt_str(&buf, msg);
		prt_str(&buf, "\ndropping pointer\n  ");
		bch2_extent_ptr_to_text(&buf, c, ptr);
		prt_str(&buf, "\nfrom:\n");
		bch2_bkey_val_to_text(&buf, c, k.s_c);
	}));

	bch2_bkey_drop_ptr_noerror(c, k, ptr);
	return true;
}

static bool ptr_has_ec(struct bch_fs *c, struct bkey_s k, struct bch_extent_ptr *ptr)
{
	struct extent_ptr_decoded p;
	union bch_extent_entry *entry;

	bkey_for_each_ptr_decode(k.k, bch2_bkey_ptrs(k), p, entry)
		if (&entry->ptr == ptr)
			return p.has_ec;
	return false;
}

static bool maybe_drop_cached_ptr(struct bch_fs *c, struct bch_inode_opts *opts,
				  struct bkey_s k,
				  struct bch_extent_ptr *ptr, bool have_cached_ptr)
{
	if (ptr->cached) {
		if (have_cached_ptr)
			return drop_cached_pointer_trace(c, k, ptr, "extent already has another cached pointer");

		if (ptr_has_ec(c, k, ptr))
			return drop_cached_pointer_trace(c, k, ptr, "cached ptr incompatible with erasure coding");

		struct bch_dev *ca = bch2_dev_rcu_noerror(c, ptr->dev);
		if (ca && dev_ptr_stale_rcu(ca, ptr))
			return drop_cached_pointer_trace(c, k, ptr, "pointer is stale");
		if (!ca || ca->mi.state == BCH_MEMBER_STATE_evacuating)
			return drop_cached_pointer_trace(c, k, ptr, "device bad or evacuating");

		unsigned target = opts->promote_target ?: opts->foreground_target;
		if (target && !bch2_dev_in_target_rcu(c, ptr->dev, target))
			return drop_cached_pointer_trace(c, k, ptr, "incorrect target");
	}

	return false;
}

void bch2_extent_ptr_set_cached(struct bch_fs *c,
				struct bch_inode_opts *opts,
				struct bkey_s k,
				struct bch_extent_ptr *ptr)
{
	unsigned drop_dev = ptr->dev;

	guard(rcu)();
	bool have_cached_ptr, dropped;
	do {
		struct bkey_ptrs ptrs = bch2_bkey_ptrs(k);
		union bch_extent_entry *entry;
		struct extent_ptr_decoded p;
		have_cached_ptr = dropped = false;

		bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
			/*
			 * Check if it's erasure coded - stripes can't contain cached
			 * data. Possibly something we can fix in the future?
			 */
			if (&entry->ptr == ptr && p.has_ec) {
				drop_cached_pointer_trace(c, k, ptr, "ptr->cached && ec currently incompatible");
				return;
			}

			if (maybe_drop_cached_ptr(c, opts, k, &entry->ptr, have_cached_ptr)) {
				/* @ptr is being invalidated; we'll have to find it again */
				ptr = NULL;
				dropped = true;
				break;
			}

			have_cached_ptr |= p.ptr.cached;
		}
	} while (dropped);

	if (!ptr) {
		struct bkey_ptrs ptrs = bch2_bkey_ptrs(k);
		bkey_for_each_ptr(ptrs, ptr2)
			if (ptr2->dev == drop_dev)
				ptr = ptr2;
	}

	ptr->cached = true;
	maybe_drop_cached_ptr(c, opts, k, ptr, have_cached_ptr);
}

static void bch2_bkey_set_ptrs_cached_mask(struct bch_fs *c,
					   struct bch_inode_opts *opts,
					   struct bkey_i *k,
					   unsigned mask)
{
	while (mask) {
		unsigned drop = __fls(mask);
		mask &= ~BIT(drop);

		bkey_for_each_ptr(bch2_bkey_ptrs(bkey_i_to_s(k)), ptr)
			if (!drop--) {
				bch2_extent_ptr_set_cached(c, opts, bkey_i_to_s(k), ptr);
				break;
			}
	}
}

#if 0
void bch2_bkey_set_ptrs_cached_mask()
{
}
#endif

static bool bch2_bkey_has_stale_ptrs(struct bch_fs *c, struct bkey_s_c k)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	struct bch_dev *ca;

	guard(rcu)();
	bkey_for_each_ptr(ptrs, ptr)
		if (ptr->cached &&
		    (ca = bch2_dev_rcu_noerror(c, ptr->dev)) &&
		    dev_ptr_stale_rcu(ca, ptr) > 0)
			return true;

	return false;
}

/*
 * bch2_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.
 */
static void __bch2_bkey_drop_stale_ptrs(struct bch_fs *c, struct bkey_s k)
{
	struct bch_dev *ca;

	guard(rcu)();
	bch2_bkey_drop_ptrs_noerror(k, p, entry,
		p.ptr.cached &&
		(!(ca = bch2_dev_rcu_noerror(c, p.ptr.dev)) ||
		 dev_ptr_stale_rcu(ca, &p.ptr) > 0));
}

int bch2_bkey_drop_stale_ptrs(struct btree_trans *trans, struct btree_iter *iter, struct bkey_s_c k)
{
	if (bch2_bkey_has_stale_ptrs(trans->c, k)) {
		struct bkey_i *u = errptr_try(bch2_bkey_make_mut(trans, iter, &k,
						      BTREE_UPDATE_internal_snapshot_node));

		__bch2_bkey_drop_stale_ptrs(trans->c, bkey_i_to_s(u));
	}

	return 0;
}

void bch2_bkey_drop_extra_cached_ptrs(struct bch_fs *c,
				      struct bch_inode_opts *opts,
				      struct bkey_s k)
{
	guard(rcu)();
	bool dropped;

	do {
		struct bkey_ptrs ptrs = bch2_bkey_ptrs(k);
		bool have_cached_ptr = false;
		dropped = false;

		bkey_for_each_ptr(ptrs, ptr) {
			if (maybe_drop_cached_ptr(c, opts, k, ptr, have_cached_ptr)) {
				dropped = true;
				break;
			}

			have_cached_ptr |= ptr->cached;
		}
	} while (dropped);
}

int bch2_bkey_drop_extra_durability(struct btree_trans *trans,
				    struct bch_inode_opts *opts,
				    struct bkey_i *k,
				    unsigned mask,
				    bool kill)
{
	if (!mask)
		return 0;

	struct bch_fs *c = trans->c;
	u8 ptr_durability[BCH_BKEY_PTRS_MAX];
	unsigned durability = 0, nr_ptrs = 0;

	memset(ptr_durability, 0, sizeof(ptr_durability));

	union bch_extent_entry *entry;
	struct extent_ptr_decoded p;

	bkey_for_each_ptr_decode(&k->k, bch2_bkey_ptrs(bkey_i_to_s(k)), p, entry) {
		BUG_ON(nr_ptrs >= ARRAY_SIZE(ptr_durability));

		if (p.ptr.cached)
			mask &= ~BIT(nr_ptrs);

		int d = bch2_dev_idx_is_online(c, p.ptr.dev)
			? bch2_extent_ptr_durability(trans, &p)
			: 0;
		if (d < 0)
			return d;

		BUG_ON(d > U8_MAX);

		ptr_durability[nr_ptrs++] = d;
		durability += d;
	}

	u8 ptrs_kill = 0;
	for (unsigned i = 0; i < nr_ptrs; i++)
		if ((mask & BIT(i)) &&
		    durability - ptr_durability[i] >= opts->data_replicas) {
			durability -= ptr_durability[i];
			ptr_durability[i] = 0;
			ptrs_kill |= BIT(i);
		}

	if (kill)
		bch2_bkey_drop_ptrs_mask(c, k, ptrs_kill);
	else
		bch2_bkey_set_ptrs_cached_mask(c, opts, k, ptrs_kill);
	return 0;
}

int bch2_bkey_drop_extra_ec_durability(struct btree_trans *trans,
				       struct bch_inode_opts *opts,
				       struct bkey_i *k, unsigned mask)
{
	if (!mask)
		return 0;

	struct bkey_durability durability;
	try(bch2_bkey_durability(trans, bkey_i_to_s_c(k), &durability));

	struct bch_fs *c = trans->c;
	union bch_extent_entry *entry;
	struct extent_ptr_decoded p;
	unsigned ptr_bit = 1;

	bkey_for_each_ptr_decode(&k->k, bch2_bkey_ptrs(bkey_i_to_s(k)), p, entry) {
		if (mask & ptr_bit) {
			int d;
			if (bch2_dev_idx_is_online(c, p.ptr.dev)) {
				d = bch2_extent_ptr_durability(trans, &p);
				if (d < 0)
					return d;

				d -= bch2_dev_durability(c, p.ptr.dev);
			} else {
				d = 0;
			}

			if (durability.online - d >= opts->data_replicas) {
				durability.online -= d;
				bch2_bkey_drop_ec(c, k, p.ptr.dev);
			}
		}
		ptr_bit <<= 1;
	}

	return 0;
}

__cold void bch2_extent_ptr_to_text(struct printbuf *out, struct bch_fs *c, const struct bch_extent_ptr *ptr)
{
	struct bch_dev *ca = c ? bch2_dev_rcu_noerror(c, ptr->dev) : NULL;
	if (!ca) {
		prt_printf(out, "%u:%llu gen %u", ptr->dev,
			   (u64) ptr->offset, ptr->gen);
	} else {
		u32 offset;
		u64 b = sector_to_bucket_and_offset(ca, ptr->offset, &offset);

		prt_printf(out, "%6s %u:%llu:%u gen %u",
			   ca->name, ptr->dev, b, offset, ptr->gen);
		if (ca->mi.durability != 1)
			prt_printf(out, " d=%u", ca->mi.durability);
		int stale = dev_ptr_stale_rcu(ca, ptr);
		if (stale)
			prt_printf(out, " stale=%i", stale);
	}

	if (ptr->cached)
		prt_str(out, " cached");
	if (ptr->unwritten)
		prt_str(out, " unwritten");
}

__cold void bch2_extent_crc_unpacked_to_text(struct printbuf *out, struct bch_extent_crc_unpacked *crc)
{
	prt_printf(out, "c_size %u size %u offset %u nonce %u csum ",
		   crc->compressed_size,
		   crc->uncompressed_size,
		   crc->offset, crc->nonce);
	bch2_prt_csum_type(out, crc->csum_type);
	prt_printf(out, " %0llx:%0llx ", crc->csum.hi, crc->csum.lo);
	prt_str(out, " compress ");
	bch2_prt_compression_type(out, crc->compression_type);
}

const char * const bch2_extent_entry_types[] = {
#define x(t, n, ...) [n] = #t,
	BCH_EXTENT_ENTRY_TYPES()
#undef x
	NULL
};

__cold 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;

	if (!c) {
		prt_printf(out, "no filesystem object available");
		return;
	}

	prt_printf(out, "durability: %u ", bch2_bkey_durability_safe(c, k));

	guard(printbuf_atomic)(out);
	guard(rcu)();

	bkey_extent_entry_for_each(ptrs, entry) {
		prt_newline(out);

		unsigned type = extent_entry_type(entry);
		if (type < BCH_EXTENT_ENTRY_MAX) {
			prt_str(out, bch2_extent_entry_types[extent_entry_type(entry)]);
			prt_str(out, ": ");
		}

		switch (type) {
		case BCH_EXTENT_ENTRY_ptr:
			bch2_extent_ptr_to_text(out, c, entry_to_ptr(entry));
			break;

		case BCH_EXTENT_ENTRY_crc32:
		case BCH_EXTENT_ENTRY_crc64:
		case BCH_EXTENT_ENTRY_crc128: {
			struct bch_extent_crc_unpacked crc =
				bch2_extent_crc_unpack(k.k, entry_to_crc(entry));

			bch2_extent_crc_unpacked_to_text(out, &crc);
			break;
		}
		case BCH_EXTENT_ENTRY_stripe_ptr: {
			const struct bch_extent_stripe_ptr *ec = &entry->stripe_ptr;

			prt_printf(out, "idx %llu block %u", (u64) ec->idx, ec->block);
			break;
		}
		case BCH_EXTENT_ENTRY_rebalance_v1:
			bch2_extent_rebalance_v1_to_text(out, c, &entry->rebalance_v1);
			break;

		case BCH_EXTENT_ENTRY_reconcile:
			bch2_extent_reconcile_to_text(out, c, &entry->reconcile);
			break;

		case BCH_EXTENT_ENTRY_flags:
			prt_bitflags(out, bch2_extent_flags_strs, entry->flags.flags);
			break;

		case BCH_EXTENT_ENTRY_reconcile_bp:
			prt_printf(out, "idx %llu", (u64) entry->reconcile_bp.idx);
			break;

		default:
			prt_printf(out, "(unknown extent entry %.16llx)", *((u64 *) entry));
			return;
		}
	}
}

static int extent_ptr_validate(struct bch_fs *c,
			       struct bkey_s_c k,
			       const struct bkey_validate_context *from,
			       const struct bch_extent_ptr *ptr,
			       unsigned size_ondisk,
			       bool metadata)
{
	int ret = 0;

	if (ptr->dev == BCH_SB_MEMBER_INVALID)
		return 0;

	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	bkey_for_each_ptr(ptrs, ptr2)
		bkey_fsck_err_on(ptr != ptr2 && ptr->dev == ptr2->dev,
				 c, ptr_to_duplicate_device,
				 "multiple pointers to same device (%u)", ptr->dev);

	/* bad pointers are repaired by check_fix_ptrs(): */
	rcu_read_lock();
	struct bch_dev *ca = bch2_dev_rcu_noerror(c, ptr->dev);
	if (!ca) {
		rcu_read_unlock();
		return 0;
	}
	u32 bucket_offset;
	u64 bucket = sector_to_bucket_and_offset(ca, ptr->offset, &bucket_offset);
	unsigned first_bucket	= ca->mi.first_bucket;
	u64 nbuckets		= ca->mi.nbuckets;
	unsigned bucket_size	= ca->mi.bucket_size;
	rcu_read_unlock();

	bkey_fsck_err_on(bucket >= nbuckets,
			 c, ptr_after_last_bucket,
			 "pointer past last bucket (%llu > %llu)", bucket, nbuckets);
	bkey_fsck_err_on(bucket < first_bucket,
			 c, ptr_before_first_bucket,
			 "pointer before first bucket (%llu < %u)", bucket, first_bucket);
	bkey_fsck_err_on(bucket_offset + size_ondisk > bucket_size,
			 c, ptr_spans_multiple_buckets,
			 "pointer spans multiple buckets (%u + %u > %u)",
		       bucket_offset, size_ondisk, bucket_size);
fsck_err:
	return ret;
}

static inline bool btree_ptr_entry_type_allowed(enum bch_extent_entry_type type)
{
	switch (type) {
	case BCH_EXTENT_ENTRY_ptr:
	case BCH_EXTENT_ENTRY_reconcile:
	case BCH_EXTENT_ENTRY_reconcile_bp:
		return true;
	default:
		return false;
	};
}

int bch2_bkey_ptrs_validate(struct bch_fs *c, struct bkey_s_c k,
			    const struct bkey_validate_context *from)
{
	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;
	unsigned nonce = UINT_MAX;
	unsigned nr_ptrs = 0;
	bool have_written = false, have_unwritten = false, have_ec = false, crc_since_last_ptr = false;
	bool have_non_inval_dev_ptrs = false;
	bool have_non_inval_dev_ptrs_dirty = false;
	int ret = 0;

	if (bkey_is_btree_ptr(k.k))
		size_ondisk = btree_sectors(c);

	bkey_extent_entry_for_each(ptrs, entry) {
		unsigned type = extent_entry_type(entry);

		bkey_fsck_err_on(type >= c->sb.extent_types_known,
				 c, extent_ptrs_invalid_entry,
				 "invalid extent entry type (got %u, max %u)",
				 type, c->sb.extent_types_known);

		bkey_fsck_err_on(bkey_is_btree_ptr(k.k) &&
				 type < BCH_EXTENT_ENTRY_MAX &&
				 !btree_ptr_entry_type_allowed(type),
				 c, btree_ptr_has_non_ptr,
				 "has non allowed field");

		switch (type) {
		case BCH_EXTENT_ENTRY_ptr:
			try(extent_ptr_validate(c, k, from, &entry->ptr, size_ondisk, false));

			bkey_fsck_err_on(entry->ptr.cached && have_ec,
					 c, ptr_cached_and_erasure_coded,
					 "cached, erasure coded ptr");

			if (entry->ptr.dev != BCH_SB_MEMBER_INVALID) {
				if (!entry->ptr.unwritten)
					have_written = true;
				else
					have_unwritten = true;
			}

			if (entry->ptr.dev != BCH_SB_MEMBER_INVALID || have_ec) {
				if (!entry->ptr.cached)
					have_non_inval_dev_ptrs_dirty = true;
				have_non_inval_dev_ptrs = true;
			}

			have_ec = false;
			crc_since_last_ptr = false;
			nr_ptrs++;
			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));

			bkey_fsck_err_on(!bch2_checksum_type_valid(c, crc.csum_type),
					 c, ptr_crc_csum_type_unknown,
					 "invalid checksum type");
			bkey_fsck_err_on(crc.compression_type >= BCH_COMPRESSION_TYPE_NR,
					 c, ptr_crc_compression_type_unknown,
					 "invalid compression type");

			bkey_fsck_err_on(crc.offset + crc.live_size > crc.uncompressed_size,
					 c, ptr_crc_uncompressed_size_too_small,
					 "checksum offset + key size > uncompressed size");
			bkey_fsck_err_on(crc_is_encoded(crc) &&
					 (crc.uncompressed_size > c->opts.encoded_extent_max >> 9) &&
					 (from->flags & (BCH_VALIDATE_write|BCH_VALIDATE_commit)),
					 c, ptr_crc_uncompressed_size_too_big,
					 "too large encoded extent");
			bkey_fsck_err_on(!crc_is_compressed(crc) &&
					 crc.compressed_size != crc.uncompressed_size,
					 c, ptr_crc_uncompressed_size_mismatch,
					 "not compressed but compressed != uncompressed size");

			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)
					bkey_fsck_err(c, ptr_crc_nonce_mismatch,
						      "incorrect nonce");
			}

			bkey_fsck_err_on(crc_since_last_ptr,
					 c, ptr_crc_redundant,
					 "redundant crc entry");
			crc_since_last_ptr = true;

			size_ondisk = crc.compressed_size;
			break;
		case BCH_EXTENT_ENTRY_stripe_ptr:
			bkey_fsck_err_on(have_ec,
					 c, ptr_stripe_redundant,
					 "redundant stripe entry");
			have_ec = true;
			break;
		case BCH_EXTENT_ENTRY_reconcile:
			try(bch2_extent_reconcile_validate(c, k, from, &entry->reconcile));
			break;
		case BCH_EXTENT_ENTRY_flags:
			bkey_fsck_err_on(entry != ptrs.start,
					 c, extent_flags_not_at_start,
					 "extent flags entry not at start");
			break;
		case BCH_EXTENT_ENTRY_reconcile_bp:
			break;
		}
	}

	bkey_fsck_err_on(!nr_ptrs,
			 c, extent_ptrs_no_ptrs,
			 "no ptrs");
	bkey_fsck_err_on(nr_ptrs > BCH_BKEY_PTRS_MAX,
			 c, extent_ptrs_too_many_ptrs,
			 "too many ptrs: %u > %u", nr_ptrs, BCH_BKEY_PTRS_MAX);
	bkey_fsck_err_on(have_written && have_unwritten,
			 c, extent_ptrs_written_and_unwritten,
			 "extent with unwritten and written ptrs");
	bkey_fsck_err_on(k.k->type != KEY_TYPE_extent && have_unwritten,
			 c, extent_ptrs_unwritten,
			 "has unwritten ptrs");
	bkey_fsck_err_on(crc_since_last_ptr,
			 c, extent_ptrs_redundant_crc,
			 "redundant crc entry");
	bkey_fsck_err_on(have_ec,
			 c, extent_ptrs_redundant_stripe,
			 "redundant stripe entry");

	if (!bkey_is_btree_ptr(k.k)) {
		/*
		 * we don't use KEY_TYPE_error for dead btree nodes - we still want the
		 * other fields in bch_btree_ptr_v2
		 */
		bkey_fsck_err_on(!have_non_inval_dev_ptrs,
				 c, extent_ptrs_all_invalid,
				 "extent without valid pointers");

		bkey_fsck_err_on(from->from == BKEY_VALIDATE_commit &&
				 !have_non_inval_dev_ptrs_dirty,
				 c, extent_ptrs_all_invalid,
				 "extent without valid dirty pointers");
	}
fsck_err:
	return ret;
}

void bch2_ptr_swab(const struct bch_fs *c, struct bkey_s k)
{
	struct bkey_ptrs ptrs = bch2_bkey_ptrs(k);
	union bch_extent_entry *entry;
	u64 *d;

	for (d =  (u64 *) ptrs.start;
	     d != (u64 *) ptrs.end;
	     d++)
		*d = swab64(*d);

	for (entry = ptrs.start;
	     entry < ptrs.end;
	     entry = extent_entry_next(c, 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;
		case BCH_EXTENT_ENTRY_rebalance_v1:
		case BCH_EXTENT_ENTRY_reconcile:
			break;
		default:
			/* Bad entry type: will be caught by validate() */
			return;
		}
	}
}

int bch2_bkey_extent_flags_set(struct bch_fs *c, struct bkey_i *k, u64 flags)
{
	try(bch2_request_incompat_feature(c, bcachefs_metadata_version_extent_flags));

	struct bkey_ptrs ptrs = bch2_bkey_ptrs(bkey_i_to_s(k));

	if (ptrs.start != ptrs.end &&
	    extent_entry_type(ptrs.start) == BCH_EXTENT_ENTRY_flags) {
		ptrs.start->flags.flags = flags;
	} else {
		struct bch_extent_flags f = {
			.type	= BIT(BCH_EXTENT_ENTRY_flags),
			.flags	= flags,
		};
		__extent_entry_insert(c, k, ptrs.start, (union bch_extent_entry *) &f);
	}

	return 0;
}

/* Generic extent code: */

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

	if (bkey_le(where, bkey_start_pos(k.k)))
		return 0;

	EBUG_ON(bkey_gt(where, k.k->p));

	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:
			case BCH_EXTENT_ENTRY_rebalance_v1:
			case BCH_EXTENT_ENTRY_reconcile:
			case BCH_EXTENT_ENTRY_flags:
			case BCH_EXTENT_ENTRY_reconcile_bp:
				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);

		SET_REFLINK_P_IDX(p.v, REFLINK_P_IDX(p.v) + sub);
		break;
	}
	case KEY_TYPE_inline_data:
	case KEY_TYPE_indirect_inline_data: {
		void *p = bkey_inline_data_p(k);
		unsigned bytes = bkey_inline_data_bytes(k.k);

		sub = min_t(u64, sub << 9, bytes);

		memmove(p, p + sub, bytes - 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_ge(where, k.k->p))
		return 0;

	EBUG_ON(bkey_lt(where, bkey_start_pos(k.k)));

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

	k.k->p.offset = where.offset;
	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:
	case KEY_TYPE_indirect_inline_data:
		new_val_u64s = (bkey_inline_data_offset(k.k) +
				min(bkey_inline_data_bytes(k.k), (u64) k.k->size << 9)) >> 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;
}
