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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: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o 2008-10-28 13:21:44 -04:00
parent 5e1f8c9e20
commit f99b25897a
5 changed files with 92 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
fs/ext4/ext4.h
View File

@ -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__

1
fs/ext4/ext4_sb.h
View File

@ -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;

81
fs/ext4/hash.c
View File

@ -35,23 +35,43 @@ 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;
while (len--) {
__u32 hash = hash1 + (hash0 ^ (*name++ * 7152373));
__u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
const unsigned char *ucp = (const unsigned char *) name;
if (hash & 0x80000000) hash -= 0x7fffffff;
while (len--) {
hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));
if (hash & 0x80000000)
hash -= 0x7fffffff;
hash1 = hash0;
hash0 = hash;
}
return (hash0 << 1);
return hash0 << 1;
}
static void str2hashbuf(const char *msg, int len, __u32 *buf, int num)
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--) {
hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));
if (hash & 0x80000000)
hash -= 0x7fffffff;
hash1 = hash0;
hash0 = hash;
}
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;
@ -62,7 +82,35 @@ 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) 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_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;
val = pad;
if (len > num*4)
len = num * 4;
for (i = 0; i < len; i++) {
if ((i % 4) == 0)
val = pad;
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:
hash = dx_hack_hash(name, len);
case DX_HASH_LEGACY_UNSIGNED:
hash = dx_hack_hash_unsigned(name, len);
break;
case DX_HASH_LEGACY:
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;

7
fs/ext4/namei.c
View File

@ -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;

12
fs/ext4/super.c
View File

@ -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