fs/ubifs/key.h - kernel/msm-4.19 - Gitiles

 /*
  * This file is part of UBIFS.
  *
  * Copyright (C) 2006-2008 Nokia Corporation.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 as published by
  * the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  * more details.
  *
  * You should have received a copy of the GNU General Public License along with
  * this program; if not, write to the Free Software Foundation, Inc., 51
  * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  *
  * Authors: Artem Bityutskiy (Битюцкий Артём)
  *          Adrian Hunter
  */

 /*
  * This header contains various key-related definitions and helper function.
  * UBIFS allows several key schemes, so we access key fields only via these
  * helpers. At the moment only one key scheme is supported.
  *
  * Simple key scheme
  * ~~~~~~~~~~~~~~~~~
  *
  * Keys are 64-bits long. First 32-bits are inode number (parent inode number
  * in case of direntry key). Next 3 bits are node type. The last 29 bits are
  * 4KiB offset in case of inode node, and direntry hash in case of a direntry
  * node. We use "r5" hash borrowed from reiserfs.
  */

 /*
  * Lot's of the key helpers require a struct ubifs_info *c as the first parameter.
  * But we are not using it at all currently. That's designed for future extensions of
  * different c->key_format. But right now, there is only one key type, UBIFS_SIMPLE_KEY_FMT.
  */

 #ifndef __UBIFS_KEY_H__
 #define __UBIFS_KEY_H__

 /**
  * key_mask_hash - mask a valid hash value.
  * @val: value to be masked
  *
  * We use hash values as offset in directories, so values %0 and %1 are
  * reserved for "." and "..". %2 is reserved for "end of readdir" marker. This
  * function makes sure the reserved values are not used.
  */
 static inline uint32_t key_mask_hash(uint32_t hash)
 {
 	hash &= UBIFS_S_KEY_HASH_MASK;
 	if (unlikely(hash <= 2))
 		hash += 3;
 	return hash;
 }

 /**
  * key_r5_hash - R5 hash function (borrowed from reiserfs).
  * @s: direntry name
  * @len: name length
  */
 static inline uint32_t key_r5_hash(const char *s, int len)
 {
 	uint32_t a = 0;
 	const signed char *str = (const signed char *)s;

 	while (len--) {
 		a += *str << 4;
 		a += *str >> 4;
 		a *= 11;
 		str++;
 	}

 	return key_mask_hash(a);
 }

 /**
  * key_test_hash - testing hash function.
  * @str: direntry name
  * @len: name length
  */
 static inline uint32_t key_test_hash(const char *str, int len)
 {
 	uint32_t a = 0;

 	len = min_t(uint32_t, len, 4);
 	memcpy(&a, str, len);
 	return key_mask_hash(a);
 }

 /**
  * ino_key_init - initialize inode key.
  * @c: UBIFS file-system description object
  * @key: key to initialize
  * @inum: inode number
  */
 static inline void ino_key_init(const struct ubifs_info *c,
 				union ubifs_key *key, ino_t inum)
 {
 	key->u32[0] = inum;
 	key->u32[1] = UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS;
 }

 /**
  * ino_key_init_flash - initialize on-flash inode key.
  * @c: UBIFS file-system description object
  * @k: key to initialize
  * @inum: inode number
  */
 static inline void ino_key_init_flash(const struct ubifs_info *c, void *k,
 				      ino_t inum)
 {
 	union ubifs_key *key = k;

 	key->j32[0] = cpu_to_le32(inum);
 	key->j32[1] = cpu_to_le32(UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS);
 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 }

 /**
  * lowest_ino_key - get the lowest possible inode key.
  * @c: UBIFS file-system description object
  * @key: key to initialize
  * @inum: inode number
  */
 static inline void lowest_ino_key(const struct ubifs_info *c,
 				union ubifs_key *key, ino_t inum)
 {
 	key->u32[0] = inum;
 	key->u32[1] = 0;
 }

 /**
  * highest_ino_key - get the highest possible inode key.
  * @c: UBIFS file-system description object
  * @key: key to initialize
  * @inum: inode number
  */
 static inline void highest_ino_key(const struct ubifs_info *c,
 				union ubifs_key *key, ino_t inum)
 {
 	key->u32[0] = inum;
 	key->u32[1] = 0xffffffff;
 }

 /**
  * dent_key_init - initialize directory entry key.
  * @c: UBIFS file-system description object
  * @key: key to initialize
  * @inum: parent inode number
  * @nm: direntry name and length
  */
 static inline void dent_key_init(const struct ubifs_info *c,
 				 union ubifs_key *key, ino_t inum,
 				 const struct qstr *nm)
 {
 	uint32_t hash = c->key_hash(nm->name, nm->len);

 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 	key->u32[0] = inum;
 	key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
 }

 /**
  * dent_key_init_hash - initialize directory entry key without re-calculating
  *                      hash function.
  * @c: UBIFS file-system description object
  * @key: key to initialize
  * @inum: parent inode number
  * @hash: direntry name hash
  */
 static inline void dent_key_init_hash(const struct ubifs_info *c,
 				      union ubifs_key *key, ino_t inum,
 				      uint32_t hash)
 {
 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 	key->u32[0] = inum;
 	key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
 }

 /**
  * dent_key_init_flash - initialize on-flash directory entry key.
  * @c: UBIFS file-system description object
  * @k: key to initialize
  * @inum: parent inode number
  * @nm: direntry name and length
  */
 static inline void dent_key_init_flash(const struct ubifs_info *c, void *k,
 				       ino_t inum, const struct qstr *nm)
 {
 	union ubifs_key *key = k;
 	uint32_t hash = c->key_hash(nm->name, nm->len);

 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 	key->j32[0] = cpu_to_le32(inum);
 	key->j32[1] = cpu_to_le32(hash |
 				  (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS));
 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 }

 /**
  * lowest_dent_key - get the lowest possible directory entry key.
  * @c: UBIFS file-system description object
  * @key: where to store the lowest key
  * @inum: parent inode number
  */
 static inline void lowest_dent_key(const struct ubifs_info *c,
 				   union ubifs_key *key, ino_t inum)
 {
 	key->u32[0] = inum;
 	key->u32[1] = UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS;
 }

 /**
  * xent_key_init - initialize extended attribute entry key.
  * @c: UBIFS file-system description object
  * @key: key to initialize
  * @inum: host inode number
  * @nm: extended attribute entry name and length
  */
 static inline void xent_key_init(const struct ubifs_info *c,
 				 union ubifs_key *key, ino_t inum,
 				 const struct qstr *nm)
 {
 	uint32_t hash = c->key_hash(nm->name, nm->len);

 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 	key->u32[0] = inum;
 	key->u32[1] = hash | (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
 }

 /**
  * xent_key_init_flash - initialize on-flash extended attribute entry key.
  * @c: UBIFS file-system description object
  * @k: key to initialize
  * @inum: host inode number
  * @nm: extended attribute entry name and length
  */
 static inline void xent_key_init_flash(const struct ubifs_info *c, void *k,
 				       ino_t inum, const struct qstr *nm)
 {
 	union ubifs_key *key = k;
 	uint32_t hash = c->key_hash(nm->name, nm->len);

 	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 	key->j32[0] = cpu_to_le32(inum);
 	key->j32[1] = cpu_to_le32(hash |
 				  (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS));
 	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 }

 /**
  * lowest_xent_key - get the lowest possible extended attribute entry key.
  * @c: UBIFS file-system description object
  * @key: where to store the lowest key
  * @inum: host inode number
  */
 static inline void lowest_xent_key(const struct ubifs_info *c,
 				   union ubifs_key *key, ino_t inum)
 {
 	key->u32[0] = inum;
 	key->u32[1] = UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS;
 }

 /**
  * data_key_init - initialize data key.
  * @c: UBIFS file-system description object
  * @key: key to initialize
  * @inum: inode number
  * @block: block number
  */
 static inline void data_key_init(const struct ubifs_info *c,
 				 union ubifs_key *key, ino_t inum,
 				 unsigned int block)
 {
 	ubifs_assert(!(block & ~UBIFS_S_KEY_BLOCK_MASK));
 	key->u32[0] = inum;
 	key->u32[1] = block | (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS);
 }

 /**
  * highest_data_key - get the highest possible data key for an inode.
  * @c: UBIFS file-system description object
  * @key: key to initialize
  * @inum: inode number
  */
 static inline void highest_data_key(const struct ubifs_info *c,
 				   union ubifs_key *key, ino_t inum)
 {
 	data_key_init(c, key, inum, UBIFS_S_KEY_BLOCK_MASK);
 }

 /**
  * trun_key_init - initialize truncation node key.
  * @c: UBIFS file-system description object
  * @key: key to initialize
  * @inum: inode number
  *
  * Note, UBIFS does not have truncation keys on the media and this function is
  * only used for purposes of replay.
  */
 static inline void trun_key_init(const struct ubifs_info *c,
 				 union ubifs_key *key, ino_t inum)
 {
 	key->u32[0] = inum;
 	key->u32[1] = UBIFS_TRUN_KEY << UBIFS_S_KEY_BLOCK_BITS;
 }

 /**
  * invalid_key_init - initialize invalid node key.
  * @c: UBIFS file-system description object
  * @key: key to initialize
  *
  * This is a helper function which marks a @key object as invalid.
  */
 static inline void invalid_key_init(const struct ubifs_info *c,
 				    union ubifs_key *key)
 {
 	key->u32[0] = 0xDEADBEAF;
 	key->u32[1] = UBIFS_INVALID_KEY;
 }

 /**
  * key_type - get key type.
  * @c: UBIFS file-system description object
  * @key: key to get type of
  */
 static inline int key_type(const struct ubifs_info *c,
 			   const union ubifs_key *key)
 {
 	return key->u32[1] >> UBIFS_S_KEY_BLOCK_BITS;
 }

 /**
  * key_type_flash - get type of a on-flash formatted key.
  * @c: UBIFS file-system description object
  * @k: key to get type of
  */
 static inline int key_type_flash(const struct ubifs_info *c, const void *k)
 {
 	const union ubifs_key *key = k;

 	return le32_to_cpu(key->j32[1]) >> UBIFS_S_KEY_BLOCK_BITS;
 }

 /**
  * key_inum - fetch inode number from key.
  * @c: UBIFS file-system description object
  * @k: key to fetch inode number from
  */
 static inline ino_t key_inum(const struct ubifs_info *c, const void *k)
 {
 	const union ubifs_key *key = k;

 	return key->u32[0];
 }

 /**
  * key_inum_flash - fetch inode number from an on-flash formatted key.
  * @c: UBIFS file-system description object
  * @k: key to fetch inode number from
  */
 static inline ino_t key_inum_flash(const struct ubifs_info *c, const void *k)
 {
 	const union ubifs_key *key = k;

 	return le32_to_cpu(key->j32[0]);
 }

 /**
  * key_hash - get directory entry hash.
  * @c: UBIFS file-system description object
  * @key: the key to get hash from
  */
 static inline uint32_t key_hash(const struct ubifs_info *c,
 				const union ubifs_key *key)
 {
 	return key->u32[1] & UBIFS_S_KEY_HASH_MASK;
 }

 /**
  * key_hash_flash - get directory entry hash from an on-flash formatted key.
  * @c: UBIFS file-system description object
  * @k: the key to get hash from
  */
 static inline uint32_t key_hash_flash(const struct ubifs_info *c, const void *k)
 {
 	const union ubifs_key *key = k;

 	return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_HASH_MASK;
 }

 /**
  * key_block - get data block number.
  * @c: UBIFS file-system description object
  * @key: the key to get the block number from
  */
 static inline unsigned int key_block(const struct ubifs_info *c,
 				     const union ubifs_key *key)
 {
 	return key->u32[1] & UBIFS_S_KEY_BLOCK_MASK;
 }

 /**
  * key_block_flash - get data block number from an on-flash formatted key.
  * @c: UBIFS file-system description object
  * @k: the key to get the block number from
  */
 static inline unsigned int key_block_flash(const struct ubifs_info *c,
 					   const void *k)
 {
 	const union ubifs_key *key = k;

 	return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_BLOCK_MASK;
 }

 /**
  * key_read - transform a key to in-memory format.
  * @c: UBIFS file-system description object
  * @from: the key to transform
  * @to: the key to store the result
  */
 static inline void key_read(const struct ubifs_info *c, const void *from,
 			    union ubifs_key *to)
 {
 	const union ubifs_key *f = from;

 	to->u32[0] = le32_to_cpu(f->j32[0]);
 	to->u32[1] = le32_to_cpu(f->j32[1]);
 }

 /**
  * key_write - transform a key from in-memory format.
  * @c: UBIFS file-system description object
  * @from: the key to transform
  * @to: the key to store the result
  */
 static inline void key_write(const struct ubifs_info *c,
 			     const union ubifs_key *from, void *to)
 {
 	union ubifs_key *t = to;

 	t->j32[0] = cpu_to_le32(from->u32[0]);
 	t->j32[1] = cpu_to_le32(from->u32[1]);
 	memset(to + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 }

 /**
  * key_write_idx - transform a key from in-memory format for the index.
  * @c: UBIFS file-system description object
  * @from: the key to transform
  * @to: the key to store the result
  */
 static inline void key_write_idx(const struct ubifs_info *c,
 				 const union ubifs_key *from, void *to)
 {
 	union ubifs_key *t = to;

 	t->j32[0] = cpu_to_le32(from->u32[0]);
 	t->j32[1] = cpu_to_le32(from->u32[1]);
 }

 /**
  * key_copy - copy a key.
  * @c: UBIFS file-system description object
  * @from: the key to copy from
  * @to: the key to copy to
  */
 static inline void key_copy(const struct ubifs_info *c,
 			    const union ubifs_key *from, union ubifs_key *to)
 {
 	to->u64[0] = from->u64[0];
 }

 /**
  * keys_cmp - compare keys.
  * @c: UBIFS file-system description object
  * @key1: the first key to compare
  * @key2: the second key to compare
  *
  * This function compares 2 keys and returns %-1 if @key1 is less than
  * @key2, %0 if the keys are equivalent and %1 if @key1 is greater than @key2.
  */
 static inline int keys_cmp(const struct ubifs_info *c,
 			   const union ubifs_key *key1,
 			   const union ubifs_key *key2)
 {
 	if (key1->u32[0] < key2->u32[0])
 		return -1;
 	if (key1->u32[0] > key2->u32[0])
 		return 1;
 	if (key1->u32[1] < key2->u32[1])
 		return -1;
 	if (key1->u32[1] > key2->u32[1])
 		return 1;

 	return 0;
 }

 /**
  * keys_eq - determine if keys are equivalent.
  * @c: UBIFS file-system description object
  * @key1: the first key to compare
  * @key2: the second key to compare
  *
  * This function compares 2 keys and returns %1 if @key1 is equal to @key2 and
  * %0 if not.
  */
 static inline int keys_eq(const struct ubifs_info *c,
 			  const union ubifs_key *key1,
 			  const union ubifs_key *key2)
 {
 	if (key1->u32[0] != key2->u32[0])
 		return 0;
 	if (key1->u32[1] != key2->u32[1])
 		return 0;
 	return 1;
 }

 /**
  * is_hash_key - is a key vulnerable to hash collisions.
  * @c: UBIFS file-system description object
  * @key: key
  *
  * This function returns %1 if @key is a hashed key or %0 otherwise.
  */
 static inline int is_hash_key(const struct ubifs_info *c,
 			      const union ubifs_key *key)
 {
 	int type = key_type(c, key);

 	return type == UBIFS_DENT_KEY || type == UBIFS_XENT_KEY;
 }

 /**
  * key_max_inode_size - get maximum file size allowed by current key format.
  * @c: UBIFS file-system description object
  */
 static inline unsigned long long key_max_inode_size(const struct ubifs_info *c)
 {
 	switch (c->key_fmt) {
 	case UBIFS_SIMPLE_KEY_FMT:
 		return (1ULL << UBIFS_S_KEY_BLOCK_BITS) * UBIFS_BLOCK_SIZE;
 	default:
 		return 0;
 	}
 }

 #endif /* !__UBIFS_KEY_H__ */
	/*
	* This file is part of UBIFS.
	*
	* Copyright (C) 2006-2008 Nokia Corporation.
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 as published by
	* the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	* more details.
	*
	* You should have received a copy of the GNU General Public License along with
	* this program; if not, write to the Free Software Foundation, Inc., 51
	* Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	*
	* Authors: Artem Bityutskiy (Битюцкий Артём)
	* Adrian Hunter
	*/

	/*
	* This header contains various key-related definitions and helper function.
	* UBIFS allows several key schemes, so we access key fields only via these
	* helpers. At the moment only one key scheme is supported.
	*
	* Simple key scheme
	* ~~~~~~~~~~~~~~~~~
	*
	* Keys are 64-bits long. First 32-bits are inode number (parent inode number
	* in case of direntry key). Next 3 bits are node type. The last 29 bits are
	* 4KiB offset in case of inode node, and direntry hash in case of a direntry
	* node. We use "r5" hash borrowed from reiserfs.
	*/

	/*
	* Lot's of the key helpers require a struct ubifs_info *c as the first parameter.
	* But we are not using it at all currently. That's designed for future extensions of
	* different c->key_format. But right now, there is only one key type, UBIFS_SIMPLE_KEY_FMT.
	*/

	#ifndef __UBIFS_KEY_H__
	#define __UBIFS_KEY_H__

	/**
	* key_mask_hash - mask a valid hash value.
	* @val: value to be masked
	*
	* We use hash values as offset in directories, so values %0 and %1 are
	* reserved for "." and "..". %2 is reserved for "end of readdir" marker. This
	* function makes sure the reserved values are not used.
	*/
	static inline uint32_t key_mask_hash(uint32_t hash)
	{
	hash &= UBIFS_S_KEY_HASH_MASK;
	if (unlikely(hash <= 2))
	hash += 3;
	return hash;
	}

	/**
	* key_r5_hash - R5 hash function (borrowed from reiserfs).
	* @s: direntry name
	* @len: name length
	*/
	static inline uint32_t key_r5_hash(const char *s, int len)
	{
	uint32_t a = 0;
	const signed char str = (const signed char )s;

	while (len--) {
	a += *str << 4;
	a += *str >> 4;
	a *= 11;
	str++;
	}

	return key_mask_hash(a);
	}

	/**
	* key_test_hash - testing hash function.
	* @str: direntry name
	* @len: name length
	*/
	static inline uint32_t key_test_hash(const char *str, int len)
	{
	uint32_t a = 0;

	len = min_t(uint32_t, len, 4);
	memcpy(&a, str, len);
	return key_mask_hash(a);
	}

	/**
	* ino_key_init - initialize inode key.
	* @c: UBIFS file-system description object
	* @key: key to initialize
	* @inum: inode number
	*/
	static inline void ino_key_init(const struct ubifs_info *c,
	union ubifs_key *key, ino_t inum)
	{
	key->u32[0] = inum;
	key->u32[1] = UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS;
	}

	/**
	* ino_key_init_flash - initialize on-flash inode key.
	* @c: UBIFS file-system description object
	* @k: key to initialize
	* @inum: inode number
	*/
	static inline void ino_key_init_flash(const struct ubifs_info c, void k,
	ino_t inum)
	{
	union ubifs_key *key = k;

	key->j32[0] = cpu_to_le32(inum);
	key->j32[1] = cpu_to_le32(UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS);
	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
	}

	/**
	* lowest_ino_key - get the lowest possible inode key.
	* @c: UBIFS file-system description object
	* @key: key to initialize
	* @inum: inode number
	*/
	static inline void lowest_ino_key(const struct ubifs_info *c,
	union ubifs_key *key, ino_t inum)
	{
	key->u32[0] = inum;
	key->u32[1] = 0;
	}

	/**
	* highest_ino_key - get the highest possible inode key.
	* @c: UBIFS file-system description object
	* @key: key to initialize
	* @inum: inode number
	*/
	static inline void highest_ino_key(const struct ubifs_info *c,
	union ubifs_key *key, ino_t inum)
	{
	key->u32[0] = inum;
	key->u32[1] = 0xffffffff;
	}

	/**
	* dent_key_init - initialize directory entry key.
	* @c: UBIFS file-system description object
	* @key: key to initialize
	* @inum: parent inode number
	* @nm: direntry name and length
	*/
	static inline void dent_key_init(const struct ubifs_info *c,
	union ubifs_key *key, ino_t inum,
	const struct qstr *nm)
	{
	uint32_t hash = c->key_hash(nm->name, nm->len);

	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
	key->u32[0] = inum;
	key->u32[1] = hash \| (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
	}

	/**
	* dent_key_init_hash - initialize directory entry key without re-calculating
	* hash function.
	* @c: UBIFS file-system description object
	* @key: key to initialize
	* @inum: parent inode number
	* @hash: direntry name hash
	*/
	static inline void dent_key_init_hash(const struct ubifs_info *c,
	union ubifs_key *key, ino_t inum,
	uint32_t hash)
	{
	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
	key->u32[0] = inum;
	key->u32[1] = hash \| (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
	}

	/**
	* dent_key_init_flash - initialize on-flash directory entry key.
	* @c: UBIFS file-system description object
	* @k: key to initialize
	* @inum: parent inode number
	* @nm: direntry name and length
	*/
	static inline void dent_key_init_flash(const struct ubifs_info c, void k,
	ino_t inum, const struct qstr *nm)
	{
	union ubifs_key *key = k;
	uint32_t hash = c->key_hash(nm->name, nm->len);

	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
	key->j32[0] = cpu_to_le32(inum);
	key->j32[1] = cpu_to_le32(hash \|
	(UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS));
	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
	}

	/**
	* lowest_dent_key - get the lowest possible directory entry key.
	* @c: UBIFS file-system description object
	* @key: where to store the lowest key
	* @inum: parent inode number
	*/
	static inline void lowest_dent_key(const struct ubifs_info *c,
	union ubifs_key *key, ino_t inum)
	{
	key->u32[0] = inum;
	key->u32[1] = UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS;
	}

	/**
	* xent_key_init - initialize extended attribute entry key.
	* @c: UBIFS file-system description object
	* @key: key to initialize
	* @inum: host inode number
	* @nm: extended attribute entry name and length
	*/
	static inline void xent_key_init(const struct ubifs_info *c,
	union ubifs_key *key, ino_t inum,
	const struct qstr *nm)
	{
	uint32_t hash = c->key_hash(nm->name, nm->len);

	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
	key->u32[0] = inum;
	key->u32[1] = hash \| (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
	}

	/**
	* xent_key_init_flash - initialize on-flash extended attribute entry key.
	* @c: UBIFS file-system description object
	* @k: key to initialize
	* @inum: host inode number
	* @nm: extended attribute entry name and length
	*/
	static inline void xent_key_init_flash(const struct ubifs_info c, void k,
	ino_t inum, const struct qstr *nm)
	{
	union ubifs_key *key = k;
	uint32_t hash = c->key_hash(nm->name, nm->len);

	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
	key->j32[0] = cpu_to_le32(inum);
	key->j32[1] = cpu_to_le32(hash \|
	(UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS));
	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
	}

	/**
	* lowest_xent_key - get the lowest possible extended attribute entry key.
	* @c: UBIFS file-system description object
	* @key: where to store the lowest key
	* @inum: host inode number
	*/
	static inline void lowest_xent_key(const struct ubifs_info *c,
	union ubifs_key *key, ino_t inum)
	{
	key->u32[0] = inum;
	key->u32[1] = UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS;
	}

	/**
	* data_key_init - initialize data key.
	* @c: UBIFS file-system description object
	* @key: key to initialize
	* @inum: inode number
	* @block: block number
	*/
	static inline void data_key_init(const struct ubifs_info *c,
	union ubifs_key *key, ino_t inum,
	unsigned int block)
	{
	ubifs_assert(!(block & ~UBIFS_S_KEY_BLOCK_MASK));
	key->u32[0] = inum;
	key->u32[1] = block \| (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS);
	}

	/**
	* highest_data_key - get the highest possible data key for an inode.
	* @c: UBIFS file-system description object
	* @key: key to initialize
	* @inum: inode number
	*/
	static inline void highest_data_key(const struct ubifs_info *c,
	union ubifs_key *key, ino_t inum)
	{
	data_key_init(c, key, inum, UBIFS_S_KEY_BLOCK_MASK);
	}

	/**
	* trun_key_init - initialize truncation node key.
	* @c: UBIFS file-system description object
	* @key: key to initialize
	* @inum: inode number
	*
	* Note, UBIFS does not have truncation keys on the media and this function is
	* only used for purposes of replay.
	*/
	static inline void trun_key_init(const struct ubifs_info *c,
	union ubifs_key *key, ino_t inum)
	{
	key->u32[0] = inum;
	key->u32[1] = UBIFS_TRUN_KEY << UBIFS_S_KEY_BLOCK_BITS;
	}

	/**
	* invalid_key_init - initialize invalid node key.
	* @c: UBIFS file-system description object
	* @key: key to initialize
	*
	* This is a helper function which marks a @key object as invalid.
	*/
	static inline void invalid_key_init(const struct ubifs_info *c,
	union ubifs_key *key)
	{
	key->u32[0] = 0xDEADBEAF;
	key->u32[1] = UBIFS_INVALID_KEY;
	}

	/**
	* key_type - get key type.
	* @c: UBIFS file-system description object
	* @key: key to get type of
	*/
	static inline int key_type(const struct ubifs_info *c,
	const union ubifs_key *key)
	{
	return key->u32[1] >> UBIFS_S_KEY_BLOCK_BITS;
	}

	/**
	* key_type_flash - get type of a on-flash formatted key.
	* @c: UBIFS file-system description object
	* @k: key to get type of
	*/
	static inline int key_type_flash(const struct ubifs_info c, const void k)
	{
	const union ubifs_key *key = k;

	return le32_to_cpu(key->j32[1]) >> UBIFS_S_KEY_BLOCK_BITS;
	}

	/**
	* key_inum - fetch inode number from key.
	* @c: UBIFS file-system description object
	* @k: key to fetch inode number from
	*/
	static inline ino_t key_inum(const struct ubifs_info c, const void k)
	{
	const union ubifs_key *key = k;

	return key->u32[0];
	}

	/**
	* key_inum_flash - fetch inode number from an on-flash formatted key.
	* @c: UBIFS file-system description object
	* @k: key to fetch inode number from
	*/
	static inline ino_t key_inum_flash(const struct ubifs_info c, const void k)
	{
	const union ubifs_key *key = k;

	return le32_to_cpu(key->j32[0]);
	}

	/**
	* key_hash - get directory entry hash.
	* @c: UBIFS file-system description object
	* @key: the key to get hash from
	*/
	static inline uint32_t key_hash(const struct ubifs_info *c,
	const union ubifs_key *key)
	{
	return key->u32[1] & UBIFS_S_KEY_HASH_MASK;
	}

	/**
	* key_hash_flash - get directory entry hash from an on-flash formatted key.
	* @c: UBIFS file-system description object
	* @k: the key to get hash from
	*/
	static inline uint32_t key_hash_flash(const struct ubifs_info c, const void k)
	{
	const union ubifs_key *key = k;

	return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_HASH_MASK;
	}

	/**
	* key_block - get data block number.
	* @c: UBIFS file-system description object
	* @key: the key to get the block number from
	*/
	static inline unsigned int key_block(const struct ubifs_info *c,
	const union ubifs_key *key)
	{
	return key->u32[1] & UBIFS_S_KEY_BLOCK_MASK;
	}

	/**
	* key_block_flash - get data block number from an on-flash formatted key.
	* @c: UBIFS file-system description object
	* @k: the key to get the block number from
	*/
	static inline unsigned int key_block_flash(const struct ubifs_info *c,
	const void *k)
	{
	const union ubifs_key *key = k;

	return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_BLOCK_MASK;
	}

	/**
	* key_read - transform a key to in-memory format.
	* @c: UBIFS file-system description object
	* @from: the key to transform
	* @to: the key to store the result
	*/
	static inline void key_read(const struct ubifs_info c, const void from,
	union ubifs_key *to)
	{
	const union ubifs_key *f = from;

	to->u32[0] = le32_to_cpu(f->j32[0]);
	to->u32[1] = le32_to_cpu(f->j32[1]);
	}

	/**
	* key_write - transform a key from in-memory format.
	* @c: UBIFS file-system description object
	* @from: the key to transform
	* @to: the key to store the result
	*/
	static inline void key_write(const struct ubifs_info *c,
	const union ubifs_key from, void to)
	{
	union ubifs_key *t = to;

	t->j32[0] = cpu_to_le32(from->u32[0]);
	t->j32[1] = cpu_to_le32(from->u32[1]);
	memset(to + 8, 0, UBIFS_MAX_KEY_LEN - 8);
	}

	/**
	* key_write_idx - transform a key from in-memory format for the index.
	* @c: UBIFS file-system description object
	* @from: the key to transform
	* @to: the key to store the result
	*/
	static inline void key_write_idx(const struct ubifs_info *c,
	const union ubifs_key from, void to)
	{
	union ubifs_key *t = to;

	t->j32[0] = cpu_to_le32(from->u32[0]);
	t->j32[1] = cpu_to_le32(from->u32[1]);
	}

	/**
	* key_copy - copy a key.
	* @c: UBIFS file-system description object
	* @from: the key to copy from
	* @to: the key to copy to
	*/
	static inline void key_copy(const struct ubifs_info *c,
	const union ubifs_key from, union ubifs_key to)
	{
	to->u64[0] = from->u64[0];
	}

	/**
	* keys_cmp - compare keys.
	* @c: UBIFS file-system description object
	* @key1: the first key to compare
	* @key2: the second key to compare
	*
	* This function compares 2 keys and returns %-1 if @key1 is less than
	* @key2, %0 if the keys are equivalent and %1 if @key1 is greater than @key2.
	*/
	static inline int keys_cmp(const struct ubifs_info *c,
	const union ubifs_key *key1,
	const union ubifs_key *key2)
	{
	if (key1->u32[0] < key2->u32[0])
	return -1;
	if (key1->u32[0] > key2->u32[0])
	return 1;
	if (key1->u32[1] < key2->u32[1])
	return -1;
	if (key1->u32[1] > key2->u32[1])
	return 1;

	return 0;
	}

	/**
	* keys_eq - determine if keys are equivalent.
	* @c: UBIFS file-system description object
	* @key1: the first key to compare
	* @key2: the second key to compare
	*
	* This function compares 2 keys and returns %1 if @key1 is equal to @key2 and
	* %0 if not.
	*/
	static inline int keys_eq(const struct ubifs_info *c,
	const union ubifs_key *key1,
	const union ubifs_key *key2)
	{
	if (key1->u32[0] != key2->u32[0])
	return 0;
	if (key1->u32[1] != key2->u32[1])
	return 0;
	return 1;
	}

	/**
	* is_hash_key - is a key vulnerable to hash collisions.
	* @c: UBIFS file-system description object
	* @key: key
	*
	* This function returns %1 if @key is a hashed key or %0 otherwise.
	*/
	static inline int is_hash_key(const struct ubifs_info *c,
	const union ubifs_key *key)
	{
	int type = key_type(c, key);

	return type == UBIFS_DENT_KEY \|\| type == UBIFS_XENT_KEY;
	}

	/**
	* key_max_inode_size - get maximum file size allowed by current key format.
	* @c: UBIFS file-system description object
	*/
	static inline unsigned long long key_max_inode_size(const struct ubifs_info *c)
	{
	switch (c->key_fmt) {
	case UBIFS_SIMPLE_KEY_FMT:
	return (1ULL << UBIFS_S_KEY_BLOCK_BITS) * UBIFS_BLOCK_SIZE;
	default:
	return 0;
	}
	}

	#endif /* !__UBIFS_KEY_H__ */