From: Theodore Ts'o Subject: [PATCH V2 1/2] ext3: Add support for non-native signed/unsigned htree hash algorithms Date: Tue, 28 Oct 2008 13:40:15 -0400 Message-ID: <1225215616-6069-1-git-send-email-tytso@mit.edu> Cc: Theodore Ts'o , akpm@linux-foundation.org, linux-kernel@vger.kernel.org To: Ext4 Developers List Return-path: Received: from www.church-of-our-saviour.ORG ([69.25.196.31]:46252 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751041AbYJ1Rkj (ORCPT ); Tue, 28 Oct 2008 13:40:39 -0400 Sender: linux-ext4-owner@vger.kernel.org List-ID: 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" Cc: akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org --- fs/ext3/hash.c | 77 ++++++++++++++++++++++++++++++++++++++------ fs/ext3/namei.c | 7 ++++ fs/ext3/super.c | 12 +++++++ include/linux/ext3_fs.h | 28 +++++++++++++++- include/linux/ext3_fs_sb.h | 1 + 5 files changed, 114 insertions(+), 11 deletions(-) diff --git a/fs/ext3/hash.c b/fs/ext3/hash.c index c30e149..7d215b4 100644 --- a/fs/ext3/hash.c +++ b/fs/ext3/hash.c @@ -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(const char *msg, int len, __u32 *buf, int num) +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_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 ext3fs_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 ext3fs_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 ext3fs_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; diff --git a/fs/ext3/namei.c b/fs/ext3/namei.c index 3e5edc9..4fb0493 100644 --- a/fs/ext3/namei.c +++ b/fs/ext3/namei.c @@ -368,6 +368,8 @@ dx_probe(struct qstr *entry, struct inode *dir, goto fail; } hinfo->hash_version = root->info.hash_version; + if (hinfo->hash_version <= DX_HASH_TEA) + hinfo->hash_version += EXT3_SB(dir->i_sb)->s_hash_unsigned; hinfo->seed = EXT3_SB(dir->i_sb)->s_hash_seed; if (entry) ext3fs_dirhash(entry->name, entry->len, hinfo); @@ -636,6 +638,9 @@ int ext3_htree_fill_tree(struct file *dir_file, __u32 start_hash, dir = dir_file->f_path.dentry->d_inode; if (!(EXT3_I(dir)->i_flags & EXT3_INDEX_FL)) { hinfo.hash_version = EXT3_SB(dir->i_sb)->s_def_hash_version; + if (hinfo.hash_version <= DX_HASH_TEA) + hinfo.hash_version += + EXT3_SB(dir->i_sb)->s_hash_unsigned; hinfo.seed = EXT3_SB(dir->i_sb)->s_hash_seed; count = htree_dirblock_to_tree(dir_file, dir, 0, &hinfo, start_hash, start_minor_hash); @@ -1398,6 +1403,8 @@ 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 += EXT3_SB(dir->i_sb)->s_hash_unsigned; hinfo.seed = EXT3_SB(dir->i_sb)->s_hash_seed; ext3fs_dirhash(name, namelen, &hinfo); frame = frames; diff --git a/fs/ext3/super.c b/fs/ext3/super.c index e5717a4..f175396 100644 --- a/fs/ext3/super.c +++ b/fs/ext3/super.c @@ -1744,6 +1744,18 @@ static int ext3_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 diff --git a/include/linux/ext3_fs.h b/include/linux/ext3_fs.h index d14f029..9004794 100644 --- a/include/linux/ext3_fs.h +++ b/include/linux/ext3_fs.h @@ -354,6 +354,13 @@ struct ext3_inode { #define EXT3_ORPHAN_FS 0x0004 /* Orphans being recovered */ /* + * Misc. filesystem flags + */ +#define EXT2_FLAGS_SIGNED_HASH 0x0001 /* Signed dirhash in use */ +#define EXT2_FLAGS_UNSIGNED_HASH 0x0002 /* Unsigned dirhash in use */ +#define EXT2_FLAGS_TEST_FILESYS 0x0004 /* to test development code */ + +/* * Mount flags */ #define EXT3_MOUNT_CHECK 0x00001 /* Do mount-time checks */ @@ -489,7 +496,23 @@ struct ext3_super_block { __u16 s_reserved_word_pad; __le32 s_default_mount_opts; __le32 s_first_meta_bg; /* First metablock block group */ - __u32 s_reserved[190]; /* Padding to the end of the block */ + __le32 s_mkfs_time; /* When the filesystem was created */ + __le32 s_jnl_blocks[17]; /* Backup of the journal inode */ + /* 64bit support valid if EXT4_FEATURE_COMPAT_64BIT */ +/*150*/ __le32 s_blocks_count_hi; /* Blocks count */ + __le32 s_r_blocks_count_hi; /* Reserved blocks count */ + __le32 s_free_blocks_count_hi; /* Free blocks count */ + __le16 s_min_extra_isize; /* All inodes have at least # bytes */ + __le16 s_want_extra_isize; /* New inodes should reserve # bytes */ + __le32 s_flags; /* Miscellaneous flags */ + __le16 s_raid_stride; /* RAID stride */ + __le16 s_mmp_interval; /* # seconds to wait in MMP checking */ + __le64 s_mmp_block; /* Block for multi-mount protection */ + __le32 s_raid_stripe_width; /* blocks on all data disks (N*stride)*/ + __u8 s_log_groups_per_flex; /* FLEX_BG group size */ + __u8 s_reserved_char_pad2; + __le16 s_reserved_pad; + __u32 s_reserved[162]; /* Padding to the end of the block */ }; #ifdef __KERNEL__ @@ -694,6 +717,9 @@ static inline __le16 ext3_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__ diff --git a/include/linux/ext3_fs_sb.h b/include/linux/ext3_fs_sb.h index b65f028..50dc80a 100644 --- a/include/linux/ext3_fs_sb.h +++ b/include/linux/ext3_fs_sb.h @@ -57,6 +57,7 @@ struct ext3_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; -- 1.5.6.1.205.ge2c7.dirty