fs/bcachefs/str_hash.h - linux/torvalds/linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _BCACHEFS_STR_HASH_H
 #define _BCACHEFS_STR_HASH_H

 #include "btree_iter.h"
 #include "btree_update.h"
 #include "checksum.h"
 #include "error.h"
 #include "inode.h"
 #include "siphash.h"
 #include "subvolume.h"
 #include "super.h"

 #include <linux/crc32c.h>
 #include <crypto/hash.h>
 #include <crypto/sha2.h>

 typedef unsigned __bitwise bch_str_hash_flags_t;

 enum bch_str_hash_flags {
 	__BCH_HASH_SET_MUST_CREATE,
 	__BCH_HASH_SET_MUST_REPLACE,
 };

 #define BCH_HASH_SET_MUST_CREATE	(__force bch_str_hash_flags_t) BIT(__BCH_HASH_SET_MUST_CREATE)
 #define BCH_HASH_SET_MUST_REPLACE	(__force bch_str_hash_flags_t) BIT(__BCH_HASH_SET_MUST_REPLACE)

 static inline enum bch_str_hash_type
 bch2_str_hash_opt_to_type(struct bch_fs *c, enum bch_str_hash_opts opt)
 {
 	switch (opt) {
 	case BCH_STR_HASH_OPT_crc32c:
 		return BCH_STR_HASH_crc32c;
 	case BCH_STR_HASH_OPT_crc64:
 		return BCH_STR_HASH_crc64;
 	case BCH_STR_HASH_OPT_siphash:
 		return c->sb.features & (1ULL << BCH_FEATURE_new_siphash)
 			? BCH_STR_HASH_siphash
 			: BCH_STR_HASH_siphash_old;
 	default:
 	     BUG();
 	}
 }

 struct bch_hash_info {
 	u8			type;
 	/*
 	 * For crc32 or crc64 string hashes the first key value of
 	 * the siphash_key (k0) is used as the key.
 	 */
 	SIPHASH_KEY	siphash_key;
 };

 static inline struct bch_hash_info
 bch2_hash_info_init(struct bch_fs *c, const struct bch_inode_unpacked *bi)
 {
 	/* XXX ick */
 	struct bch_hash_info info = {
 		.type = (bi->bi_flags >> INODE_STR_HASH_OFFSET) &
 			~(~0U << INODE_STR_HASH_BITS),
 		.siphash_key = { .k0 = bi->bi_hash_seed }
 	};

 	if (unlikely(info.type == BCH_STR_HASH_siphash_old)) {
 		SHASH_DESC_ON_STACK(desc, c->sha256);
 		u8 digest[SHA256_DIGEST_SIZE];

 		desc->tfm = c->sha256;

 		crypto_shash_digest(desc, (void *) &bi->bi_hash_seed,
 				    sizeof(bi->bi_hash_seed), digest);
 		memcpy(&info.siphash_key, digest, sizeof(info.siphash_key));
 	}

 	return info;
 }

 struct bch_str_hash_ctx {
 	union {
 		u32		crc32c;
 		u64		crc64;
 		SIPHASH_CTX	siphash;
 	};
 };

 static inline void bch2_str_hash_init(struct bch_str_hash_ctx *ctx,
 				     const struct bch_hash_info *info)
 {
 	switch (info->type) {
 	case BCH_STR_HASH_crc32c:
 		ctx->crc32c = crc32c(~0, &info->siphash_key.k0,
 				     sizeof(info->siphash_key.k0));
 		break;
 	case BCH_STR_HASH_crc64:
 		ctx->crc64 = crc64_be(~0, &info->siphash_key.k0,
 				      sizeof(info->siphash_key.k0));
 		break;
 	case BCH_STR_HASH_siphash_old:
 	case BCH_STR_HASH_siphash:
 		SipHash24_Init(&ctx->siphash, &info->siphash_key);
 		break;
 	default:
 		BUG();
 	}
 }

 static inline void bch2_str_hash_update(struct bch_str_hash_ctx *ctx,
 				       const struct bch_hash_info *info,
 				       const void *data, size_t len)
 {
 	switch (info->type) {
 	case BCH_STR_HASH_crc32c:
 		ctx->crc32c = crc32c(ctx->crc32c, data, len);
 		break;
 	case BCH_STR_HASH_crc64:
 		ctx->crc64 = crc64_be(ctx->crc64, data, len);
 		break;
 	case BCH_STR_HASH_siphash_old:
 	case BCH_STR_HASH_siphash:
 		SipHash24_Update(&ctx->siphash, data, len);
 		break;
 	default:
 		BUG();
 	}
 }

 static inline u64 bch2_str_hash_end(struct bch_str_hash_ctx *ctx,
 				   const struct bch_hash_info *info)
 {
 	switch (info->type) {
 	case BCH_STR_HASH_crc32c:
 		return ctx->crc32c;
 	case BCH_STR_HASH_crc64:
 		return ctx->crc64 >> 1;
 	case BCH_STR_HASH_siphash_old:
 	case BCH_STR_HASH_siphash:
 		return SipHash24_End(&ctx->siphash) >> 1;
 	default:
 		BUG();
 	}
 }

 struct bch_hash_desc {
 	enum btree_id	btree_id;
 	u8		key_type;

 	u64		(*hash_key)(const struct bch_hash_info *, const void *);
 	u64		(*hash_bkey)(const struct bch_hash_info *, struct bkey_s_c);
 	bool		(*cmp_key)(struct bkey_s_c, const void *);
 	bool		(*cmp_bkey)(struct bkey_s_c, struct bkey_s_c);
 	bool		(*is_visible)(subvol_inum inum, struct bkey_s_c);
 };

 static inline bool is_visible_key(struct bch_hash_desc desc, subvol_inum inum, struct bkey_s_c k)
 {
 	return k.k->type == desc.key_type &&
 		(!desc.is_visible ||
 		 !inum.inum ||
 		 desc.is_visible(inum, k));
 }

 static __always_inline int
 bch2_hash_lookup_in_snapshot(struct btree_trans *trans,
 		 struct btree_iter *iter,
 		 const struct bch_hash_desc desc,
 		 const struct bch_hash_info *info,
 		 subvol_inum inum, const void *key,
 		 unsigned flags, u32 snapshot)
 {
 	struct bkey_s_c k;
 	int ret;

 	for_each_btree_key_upto_norestart(trans, *iter, desc.btree_id,
 			   SPOS(inum.inum, desc.hash_key(info, key), snapshot),
 			   POS(inum.inum, U64_MAX),
 			   BTREE_ITER_SLOTS|flags, k, ret) {
 		if (is_visible_key(desc, inum, k)) {
 			if (!desc.cmp_key(k, key))
 				return 0;
 		} else if (k.k->type == KEY_TYPE_hash_whiteout) {
 			;
 		} else {
 			/* hole, not found */
 			break;
 		}
 	}
 	bch2_trans_iter_exit(trans, iter);

 	return ret ?: -BCH_ERR_ENOENT_str_hash_lookup;
 }

 static __always_inline int
 bch2_hash_lookup(struct btree_trans *trans,
 		 struct btree_iter *iter,
 		 const struct bch_hash_desc desc,
 		 const struct bch_hash_info *info,
 		 subvol_inum inum, const void *key,
 		 unsigned flags)
 {
 	u32 snapshot;
 	return  bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot) ?:
 		bch2_hash_lookup_in_snapshot(trans, iter, desc, info, inum, key, flags, snapshot);
 }

 static __always_inline int
 bch2_hash_hole(struct btree_trans *trans,
 	       struct btree_iter *iter,
 	       const struct bch_hash_desc desc,
 	       const struct bch_hash_info *info,
 	       subvol_inum inum, const void *key)
 {
 	struct bkey_s_c k;
 	u32 snapshot;
 	int ret;

 	ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
 	if (ret)
 		return ret;

 	for_each_btree_key_upto_norestart(trans, *iter, desc.btree_id,
 			   SPOS(inum.inum, desc.hash_key(info, key), snapshot),
 			   POS(inum.inum, U64_MAX),
 			   BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret)
 		if (!is_visible_key(desc, inum, k))
 			return 0;
 	bch2_trans_iter_exit(trans, iter);

 	return ret ?: -BCH_ERR_ENOSPC_str_hash_create;
 }

 static __always_inline
 int bch2_hash_needs_whiteout(struct btree_trans *trans,
 			     const struct bch_hash_desc desc,
 			     const struct bch_hash_info *info,
 			     struct btree_iter *start)
 {
 	struct btree_iter iter;
 	struct bkey_s_c k;
 	int ret;

 	bch2_trans_copy_iter(&iter, start);

 	bch2_btree_iter_advance(&iter);

 	for_each_btree_key_continue_norestart(iter, BTREE_ITER_SLOTS, k, ret) {
 		if (k.k->type != desc.key_type &&
 		    k.k->type != KEY_TYPE_hash_whiteout)
 			break;

 		if (k.k->type == desc.key_type &&
 		    desc.hash_bkey(info, k) <= start->pos.offset) {
 			ret = 1;
 			break;
 		}
 	}

 	bch2_trans_iter_exit(trans, &iter);
 	return ret;
 }

 static __always_inline
 int bch2_hash_set_in_snapshot(struct btree_trans *trans,
 			   const struct bch_hash_desc desc,
 			   const struct bch_hash_info *info,
 			   subvol_inum inum, u32 snapshot,
 			   struct bkey_i *insert,
 			   bch_str_hash_flags_t str_hash_flags,
 			   int update_flags)
 {
 	struct btree_iter iter, slot = { NULL };
 	struct bkey_s_c k;
 	bool found = false;
 	int ret;

 	for_each_btree_key_upto_norestart(trans, iter, desc.btree_id,
 			   SPOS(insert->k.p.inode,
 				desc.hash_bkey(info, bkey_i_to_s_c(insert)),
 				snapshot),
 			   POS(insert->k.p.inode, U64_MAX),
 			   BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
 		if (is_visible_key(desc, inum, k)) {
 			if (!desc.cmp_bkey(k, bkey_i_to_s_c(insert)))
 				goto found;

 			/* hash collision: */
 			continue;
 		}

 		if (!slot.path &&
 		    !(str_hash_flags & BCH_HASH_SET_MUST_REPLACE))
 			bch2_trans_copy_iter(&slot, &iter);

 		if (k.k->type != KEY_TYPE_hash_whiteout)
 			goto not_found;
 	}

 	if (!ret)
 		ret = -BCH_ERR_ENOSPC_str_hash_create;
 out:
 	bch2_trans_iter_exit(trans, &slot);
 	bch2_trans_iter_exit(trans, &iter);

 	return ret;
 found:
 	found = true;
 not_found:

 	if (!found && (str_hash_flags & BCH_HASH_SET_MUST_REPLACE)) {
 		ret = -BCH_ERR_ENOENT_str_hash_set_must_replace;
 	} else if (found && (str_hash_flags & BCH_HASH_SET_MUST_CREATE)) {
 		ret = -EEXIST;
 	} else {
 		if (!found && slot.path)
 			swap(iter, slot);

 		insert->k.p = iter.pos;
 		ret = bch2_trans_update(trans, &iter, insert, update_flags);
 	}

 	goto out;
 }

 static __always_inline
 int bch2_hash_set(struct btree_trans *trans,
 		  const struct bch_hash_desc desc,
 		  const struct bch_hash_info *info,
 		  subvol_inum inum,
 		  struct bkey_i *insert,
 		  bch_str_hash_flags_t str_hash_flags)
 {
 	insert->k.p.inode = inum.inum;

 	u32 snapshot;
 	return  bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot) ?:
 		bch2_hash_set_in_snapshot(trans, desc, info, inum,
 					  snapshot, insert, str_hash_flags, 0);
 }

 static __always_inline
 int bch2_hash_delete_at(struct btree_trans *trans,
 			const struct bch_hash_desc desc,
 			const struct bch_hash_info *info,
 			struct btree_iter *iter,
 			unsigned update_flags)
 {
 	struct bkey_i *delete;
 	int ret;

 	delete = bch2_trans_kmalloc(trans, sizeof(*delete));
 	ret = PTR_ERR_OR_ZERO(delete);
 	if (ret)
 		return ret;

 	ret = bch2_hash_needs_whiteout(trans, desc, info, iter);
 	if (ret < 0)
 		return ret;

 	bkey_init(&delete->k);
 	delete->k.p = iter->pos;
 	delete->k.type = ret ? KEY_TYPE_hash_whiteout : KEY_TYPE_deleted;

 	return bch2_trans_update(trans, iter, delete, update_flags);
 }

 static __always_inline
 int bch2_hash_delete(struct btree_trans *trans,
 		     const struct bch_hash_desc desc,
 		     const struct bch_hash_info *info,
 		     subvol_inum inum, const void *key)
 {
 	struct btree_iter iter;
 	int ret;

 	ret = bch2_hash_lookup(trans, &iter, desc, info, inum, key,
 				BTREE_ITER_INTENT);
 	if (ret)
 		return ret;

 	ret = bch2_hash_delete_at(trans, desc, info, &iter, 0);
 	bch2_trans_iter_exit(trans, &iter);
 	return ret;
 }

 #endif /* _BCACHEFS_STR_HASH_H */
	/* SPDX-License-Identifier: GPL-2.0 */
	#ifndef _BCACHEFS_STR_HASH_H
	#define _BCACHEFS_STR_HASH_H

	#include "btree_iter.h"
	#include "btree_update.h"
	#include "checksum.h"
	#include "error.h"
	#include "inode.h"
	#include "siphash.h"
	#include "subvolume.h"
	#include "super.h"

	#include <linux/crc32c.h>
	#include <crypto/hash.h>
	#include <crypto/sha2.h>

	typedef unsigned __bitwise bch_str_hash_flags_t;

	enum bch_str_hash_flags {
	__BCH_HASH_SET_MUST_CREATE,
	__BCH_HASH_SET_MUST_REPLACE,
	};

	#define BCH_HASH_SET_MUST_CREATE (__force bch_str_hash_flags_t) BIT(__BCH_HASH_SET_MUST_CREATE)
	#define BCH_HASH_SET_MUST_REPLACE (__force bch_str_hash_flags_t) BIT(__BCH_HASH_SET_MUST_REPLACE)

	static inline enum bch_str_hash_type
	bch2_str_hash_opt_to_type(struct bch_fs *c, enum bch_str_hash_opts opt)
	{
	switch (opt) {
	case BCH_STR_HASH_OPT_crc32c:
	return BCH_STR_HASH_crc32c;
	case BCH_STR_HASH_OPT_crc64:
	return BCH_STR_HASH_crc64;
	case BCH_STR_HASH_OPT_siphash:
	return c->sb.features & (1ULL << BCH_FEATURE_new_siphash)
	? BCH_STR_HASH_siphash
	: BCH_STR_HASH_siphash_old;
	default:
	BUG();
	}
	}

	struct bch_hash_info {
	u8 type;
	/*
	* For crc32 or crc64 string hashes the first key value of
	* the siphash_key (k0) is used as the key.
	*/
	SIPHASH_KEY siphash_key;
	};

	static inline struct bch_hash_info
	bch2_hash_info_init(struct bch_fs c, const struct bch_inode_unpacked bi)
	{
	/* XXX ick */
	struct bch_hash_info info = {
	.type = (bi->bi_flags >> INODE_STR_HASH_OFFSET) &
	~(~0U << INODE_STR_HASH_BITS),
	.siphash_key = { .k0 = bi->bi_hash_seed }
	};

	if (unlikely(info.type == BCH_STR_HASH_siphash_old)) {
	SHASH_DESC_ON_STACK(desc, c->sha256);
	u8 digest[SHA256_DIGEST_SIZE];

	desc->tfm = c->sha256;

	crypto_shash_digest(desc, (void *) &bi->bi_hash_seed,
	sizeof(bi->bi_hash_seed), digest);
	memcpy(&info.siphash_key, digest, sizeof(info.siphash_key));
	}

	return info;
	}

	struct bch_str_hash_ctx {
	union {
	u32 crc32c;
	u64 crc64;
	SIPHASH_CTX siphash;
	};
	};

	static inline void bch2_str_hash_init(struct bch_str_hash_ctx *ctx,
	const struct bch_hash_info *info)
	{
	switch (info->type) {
	case BCH_STR_HASH_crc32c:
	ctx->crc32c = crc32c(~0, &info->siphash_key.k0,
	sizeof(info->siphash_key.k0));
	break;
	case BCH_STR_HASH_crc64:
	ctx->crc64 = crc64_be(~0, &info->siphash_key.k0,
	sizeof(info->siphash_key.k0));
	break;
	case BCH_STR_HASH_siphash_old:
	case BCH_STR_HASH_siphash:
	SipHash24_Init(&ctx->siphash, &info->siphash_key);
	break;
	default:
	BUG();
	}
	}

	static inline void bch2_str_hash_update(struct bch_str_hash_ctx *ctx,
	const struct bch_hash_info *info,
	const void *data, size_t len)
	{
	switch (info->type) {
	case BCH_STR_HASH_crc32c:
	ctx->crc32c = crc32c(ctx->crc32c, data, len);
	break;
	case BCH_STR_HASH_crc64:
	ctx->crc64 = crc64_be(ctx->crc64, data, len);
	break;
	case BCH_STR_HASH_siphash_old:
	case BCH_STR_HASH_siphash:
	SipHash24_Update(&ctx->siphash, data, len);
	break;
	default:
	BUG();
	}
	}

	static inline u64 bch2_str_hash_end(struct bch_str_hash_ctx *ctx,
	const struct bch_hash_info *info)
	{
	switch (info->type) {
	case BCH_STR_HASH_crc32c:
	return ctx->crc32c;
	case BCH_STR_HASH_crc64:
	return ctx->crc64 >> 1;
	case BCH_STR_HASH_siphash_old:
	case BCH_STR_HASH_siphash:
	return SipHash24_End(&ctx->siphash) >> 1;
	default:
	BUG();
	}
	}

	struct bch_hash_desc {
	enum btree_id btree_id;
	u8 key_type;

	u64 (hash_key)(const struct bch_hash_info , const void *);
	u64 (hash_bkey)(const struct bch_hash_info , struct bkey_s_c);
	bool (cmp_key)(struct bkey_s_c, const void );
	bool (*cmp_bkey)(struct bkey_s_c, struct bkey_s_c);
	bool (*is_visible)(subvol_inum inum, struct bkey_s_c);
	};

	static inline bool is_visible_key(struct bch_hash_desc desc, subvol_inum inum, struct bkey_s_c k)
	{
	return k.k->type == desc.key_type &&
	(!desc.is_visible \|\|
	!inum.inum \|\|
	desc.is_visible(inum, k));
	}

	static __always_inline int
	bch2_hash_lookup_in_snapshot(struct btree_trans *trans,
	struct btree_iter *iter,
	const struct bch_hash_desc desc,
	const struct bch_hash_info *info,
	subvol_inum inum, const void *key,
	unsigned flags, u32 snapshot)
	{
	struct bkey_s_c k;
	int ret;

	for_each_btree_key_upto_norestart(trans, *iter, desc.btree_id,
	SPOS(inum.inum, desc.hash_key(info, key), snapshot),
	POS(inum.inum, U64_MAX),
	BTREE_ITER_SLOTS\|flags, k, ret) {
	if (is_visible_key(desc, inum, k)) {
	if (!desc.cmp_key(k, key))
	return 0;
	} else if (k.k->type == KEY_TYPE_hash_whiteout) {
	;
	} else {
	/* hole, not found */
	break;
	}
	}
	bch2_trans_iter_exit(trans, iter);

	return ret ?: -BCH_ERR_ENOENT_str_hash_lookup;
	}

	static __always_inline int
	bch2_hash_lookup(struct btree_trans *trans,
	struct btree_iter *iter,
	const struct bch_hash_desc desc,
	const struct bch_hash_info *info,
	subvol_inum inum, const void *key,
	unsigned flags)
	{
	u32 snapshot;
	return bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot) ?:
	bch2_hash_lookup_in_snapshot(trans, iter, desc, info, inum, key, flags, snapshot);
	}

	static __always_inline int
	bch2_hash_hole(struct btree_trans *trans,
	struct btree_iter *iter,
	const struct bch_hash_desc desc,
	const struct bch_hash_info *info,
	subvol_inum inum, const void *key)
	{
	struct bkey_s_c k;
	u32 snapshot;
	int ret;

	ret = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
	if (ret)
	return ret;

	for_each_btree_key_upto_norestart(trans, *iter, desc.btree_id,
	SPOS(inum.inum, desc.hash_key(info, key), snapshot),
	POS(inum.inum, U64_MAX),
	BTREE_ITER_SLOTS\|BTREE_ITER_INTENT, k, ret)
	if (!is_visible_key(desc, inum, k))
	return 0;
	bch2_trans_iter_exit(trans, iter);

	return ret ?: -BCH_ERR_ENOSPC_str_hash_create;
	}

	static __always_inline
	int bch2_hash_needs_whiteout(struct btree_trans *trans,
	const struct bch_hash_desc desc,
	const struct bch_hash_info *info,
	struct btree_iter *start)
	{
	struct btree_iter iter;
	struct bkey_s_c k;
	int ret;

	bch2_trans_copy_iter(&iter, start);

	bch2_btree_iter_advance(&iter);

	for_each_btree_key_continue_norestart(iter, BTREE_ITER_SLOTS, k, ret) {
	if (k.k->type != desc.key_type &&
	k.k->type != KEY_TYPE_hash_whiteout)
	break;

	if (k.k->type == desc.key_type &&
	desc.hash_bkey(info, k) <= start->pos.offset) {
	ret = 1;
	break;
	}
	}

	bch2_trans_iter_exit(trans, &iter);
	return ret;
	}

	static __always_inline
	int bch2_hash_set_in_snapshot(struct btree_trans *trans,
	const struct bch_hash_desc desc,
	const struct bch_hash_info *info,
	subvol_inum inum, u32 snapshot,
	struct bkey_i *insert,
	bch_str_hash_flags_t str_hash_flags,
	int update_flags)
	{
	struct btree_iter iter, slot = { NULL };
	struct bkey_s_c k;
	bool found = false;
	int ret;

	for_each_btree_key_upto_norestart(trans, iter, desc.btree_id,
	SPOS(insert->k.p.inode,
	desc.hash_bkey(info, bkey_i_to_s_c(insert)),
	snapshot),
	POS(insert->k.p.inode, U64_MAX),
	BTREE_ITER_SLOTS\|BTREE_ITER_INTENT, k, ret) {
	if (is_visible_key(desc, inum, k)) {
	if (!desc.cmp_bkey(k, bkey_i_to_s_c(insert)))
	goto found;

	/* hash collision: */
	continue;
	}

	if (!slot.path &&
	!(str_hash_flags & BCH_HASH_SET_MUST_REPLACE))
	bch2_trans_copy_iter(&slot, &iter);

	if (k.k->type != KEY_TYPE_hash_whiteout)
	goto not_found;
	}

	if (!ret)
	ret = -BCH_ERR_ENOSPC_str_hash_create;
	out:
	bch2_trans_iter_exit(trans, &slot);
	bch2_trans_iter_exit(trans, &iter);

	return ret;
	found:
	found = true;
	not_found:

	if (!found && (str_hash_flags & BCH_HASH_SET_MUST_REPLACE)) {
	ret = -BCH_ERR_ENOENT_str_hash_set_must_replace;
	} else if (found && (str_hash_flags & BCH_HASH_SET_MUST_CREATE)) {
	ret = -EEXIST;
	} else {
	if (!found && slot.path)
	swap(iter, slot);

	insert->k.p = iter.pos;
	ret = bch2_trans_update(trans, &iter, insert, update_flags);
	}

	goto out;
	}

	static __always_inline
	int bch2_hash_set(struct btree_trans *trans,
	const struct bch_hash_desc desc,
	const struct bch_hash_info *info,
	subvol_inum inum,
	struct bkey_i *insert,
	bch_str_hash_flags_t str_hash_flags)
	{
	insert->k.p.inode = inum.inum;

	u32 snapshot;
	return bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot) ?:
	bch2_hash_set_in_snapshot(trans, desc, info, inum,
	snapshot, insert, str_hash_flags, 0);
	}

	static __always_inline
	int bch2_hash_delete_at(struct btree_trans *trans,
	const struct bch_hash_desc desc,
	const struct bch_hash_info *info,
	struct btree_iter *iter,
	unsigned update_flags)
	{
	struct bkey_i *delete;
	int ret;

	delete = bch2_trans_kmalloc(trans, sizeof(*delete));
	ret = PTR_ERR_OR_ZERO(delete);
	if (ret)
	return ret;

	ret = bch2_hash_needs_whiteout(trans, desc, info, iter);
	if (ret < 0)
	return ret;

	bkey_init(&delete->k);
	delete->k.p = iter->pos;
	delete->k.type = ret ? KEY_TYPE_hash_whiteout : KEY_TYPE_deleted;

	return bch2_trans_update(trans, iter, delete, update_flags);
	}

	static __always_inline
	int bch2_hash_delete(struct btree_trans *trans,
	const struct bch_hash_desc desc,
	const struct bch_hash_info *info,
	subvol_inum inum, const void *key)
	{
	struct btree_iter iter;
	int ret;

	ret = bch2_hash_lookup(trans, &iter, desc, info, inum, key,
	BTREE_ITER_INTENT);
	if (ret)
	return ret;

	ret = bch2_hash_delete_at(trans, desc, info, &iter, 0);
	bch2_trans_iter_exit(trans, &iter);
	return ret;
	}

	#endif /* _BCACHEFS_STR_HASH_H */