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Commit f99b2589 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: Add support for non-native signed/unsigned htree hash algorithms 



The original ext3 hash algorithms assumed that variables of type char
were signed, as God and K&R intended.  Unfortunately, this assumption
is not true on some architectures.  Userspace support for marking
filesystems with non-native signed/unsigned chars was added two years
ago, but the kernel-side support was never added (until now).

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 5e1f8c9e

fs/ext4/ext4.h

+3 −0
Original line number Diff line number Diff line
@@ -891,6 +891,9 @@ static inline __le16 ext4_rec_len_to_disk(unsigned len) 
#define DX_HASH_LEGACY		0

#define DX_HASH_HALF_MD4	1

#define DX_HASH_TEA		2

#define DX_HASH_LEGACY_UNSIGNED	3

#define DX_HASH_HALF_MD4_UNSIGNED	4

#define DX_HASH_TEA_UNSIGNED		5



#ifdef __KERNEL__

fs/ext4/ext4_sb.h

+1 −0
Original line number Diff line number Diff line
@@ -57,6 +57,7 @@ struct ext4_sb_info { 
	u32 s_next_generation;

	u32 s_hash_seed[4];

	int s_def_hash_version;

	int s_hash_unsigned;	/* 3 if hash should be signed, 0 if not */

	struct percpu_counter s_freeblocks_counter;

	struct percpu_counter s_freeinodes_counter;

	struct percpu_counter s_dirs_counter;

fs/ext4/hash.c

+67 −10
Original line number Diff line number Diff line
@@ -35,23 +35,71 @@ static void TEA_transform(__u32 buf[4], __u32 const in[]) 




/* The old legacy hash */

static __u32 dx_hack_hash(const char *name, int len)

static __u32 dx_hack_hash_unsigned(const char *name, int len)

{

	__u32 hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;

	__u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;

	const unsigned char *ucp = (const unsigned char *) name;



	while (len--) {

		hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));



		if (hash & 0x80000000)

			hash -= 0x7fffffff;

		hash1 = hash0;

		hash0 = hash;

	}

	return hash0 << 1;

}



static __u32 dx_hack_hash_signed(const char *name, int len)

{

	__u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;

	const signed char *scp = (const signed char *) name;



	while (len--) {

		__u32 hash = hash1 + (hash0 ^ (*name++ * 7152373));

		hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));



		if (hash & 0x80000000) hash -= 0x7fffffff;

		if (hash & 0x80000000)

			hash -= 0x7fffffff;

		hash1 = hash0;

		hash0 = hash;

	}

	return (hash0 << 1);

	return hash0 << 1;

}



static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num)

{

	__u32	pad, val;

	int	i;

	const signed char *scp = (const signed char *) msg;



	pad = (__u32)len | ((__u32)len << 8);

	pad |= pad << 16;



	val = pad;

	if (len > num*4)

		len = num * 4;

	for (i = 0; i < len; i++) {

		if ((i % 4) == 0)

			val = pad;

		val = ((int) scp[i]) + (val << 8);

		if ((i % 4) == 3) {

			*buf++ = val;

			val = pad;

			num--;

		}

	}

	if (--num >= 0)

		*buf++ = val;

	while (--num >= 0)

		*buf++ = pad;

}



static void str2hashbuf(const char *msg, int len, __u32 *buf, int num)

static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num)

{

	__u32	pad, val;

	int	i;

	const unsigned char *ucp = (const unsigned char *) msg;



	pad = (__u32)len | ((__u32)len << 8);

	pad |= pad << 16;
@@ -62,7 +110,7 @@ static void str2hashbuf(const char *msg, int len, __u32 *buf, int num) 
	for (i = 0; i < len; i++) {

		if ((i % 4) == 0)

			val = pad;

		val = msg[i] + (val << 8);

		val = ((int) ucp[i]) + (val << 8);

		if ((i % 4) == 3) {

			*buf++ = val;

			val = pad;
@@ -95,6 +143,8 @@ int ext4fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo) 
	const char	*p;

	int		i;

	__u32		in[8], buf[4];

	void		(*str2hashbuf)(const char *, int, __u32 *, int) =

				str2hashbuf_signed;



	/* Initialize the default seed for the hash checksum functions */

	buf[0] = 0x67452301;
@@ -113,13 +163,18 @@ int ext4fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo) 
	}



	switch (hinfo->hash_version) {

	case DX_HASH_LEGACY_UNSIGNED:

		hash = dx_hack_hash_unsigned(name, len);

		break;

	case DX_HASH_LEGACY:

		hash = dx_hack_hash(name, len);

		hash = dx_hack_hash_signed(name, len);

		break;

	case DX_HASH_HALF_MD4_UNSIGNED:

		str2hashbuf = str2hashbuf_unsigned;

	case DX_HASH_HALF_MD4:

		p = name;

		while (len > 0) {

			str2hashbuf(p, len, in, 8);

			(*str2hashbuf)(p, len, in, 8);

			half_md4_transform(buf, in);

			len -= 32;

			p += 32;
@@ -127,10 +182,12 @@ int ext4fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo) 
		minor_hash = buf[2];

		hash = buf[1];

		break;

	case DX_HASH_TEA_UNSIGNED:

		str2hashbuf = str2hashbuf_unsigned;

	case DX_HASH_TEA:

		p = name;

		while (len > 0) {

			str2hashbuf(p, len, in, 4);

			(*str2hashbuf)(p, len, in, 4);

			TEA_transform(buf, in);

			len -= 16;

			p += 16;

fs/ext4/namei.c

+7 −0
Original line number Diff line number Diff line
@@ -372,6 +372,8 @@ dx_probe(const struct qstr *d_name, struct inode *dir, 
		goto fail;

	}

	hinfo->hash_version = root->info.hash_version;

	if (hinfo->hash_version <= DX_HASH_TEA)

		hinfo->hash_version += EXT4_SB(dir->i_sb)->s_hash_unsigned;

	hinfo->seed = EXT4_SB(dir->i_sb)->s_hash_seed;

	if (d_name)

		ext4fs_dirhash(d_name->name, d_name->len, hinfo);
@@ -641,6 +643,9 @@ int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash, 
	dir = dir_file->f_path.dentry->d_inode;

	if (!(EXT4_I(dir)->i_flags & EXT4_INDEX_FL)) {

		hinfo.hash_version = EXT4_SB(dir->i_sb)->s_def_hash_version;

		if (hinfo.hash_version <= DX_HASH_TEA)

			hinfo.hash_version +=

				EXT4_SB(dir->i_sb)->s_hash_unsigned;

		hinfo.seed = EXT4_SB(dir->i_sb)->s_hash_seed;

		count = htree_dirblock_to_tree(dir_file, dir, 0, &hinfo,

					       start_hash, start_minor_hash);
@@ -1408,6 +1413,8 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry, 


	/* Initialize as for dx_probe */

	hinfo.hash_version = root->info.hash_version;

	if (hinfo.hash_version <= DX_HASH_TEA)

		hinfo.hash_version += EXT4_SB(dir->i_sb)->s_hash_unsigned;

	hinfo.seed = EXT4_SB(dir->i_sb)->s_hash_seed;

	ext4fs_dirhash(name, namelen, &hinfo);

	frame = frames;

fs/ext4/super.c

+12 −0
Original line number Diff line number Diff line
@@ -2118,6 +2118,18 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) 
	for (i = 0; i < 4; i++)

		sbi->s_hash_seed[i] = le32_to_cpu(es->s_hash_seed[i]);

	sbi->s_def_hash_version = es->s_def_hash_version;

	i = le32_to_cpu(es->s_flags);

	if (i & EXT2_FLAGS_UNSIGNED_HASH)

		sbi->s_hash_unsigned = 3;

	else if ((i & EXT2_FLAGS_SIGNED_HASH) == 0) {

#ifdef __CHAR_UNSIGNED__

		es->s_flags |= cpu_to_le32(EXT2_FLAGS_UNSIGNED_HASH);

		sbi->s_hash_unsigned = 3;

#else

		es->s_flags |= cpu_to_le32(EXT2_FLAGS_SIGNED_HASH);

#endif

		sb->s_dirt = 1;

	}



	if (sbi->s_blocks_per_group > blocksize * 8) {

		printk(KERN_ERR