From 5875bf287d95314c58add01184f361cc5aa38429 Mon Sep 17 00:00:00 2001 From: Tetsuhiro Kohada Date: Fri, 29 May 2020 19:14:59 +0900 Subject: [Backport 5875bf287d95] exfat: standardize checksum calculation To clarify that it is a 16-bit checksum, the parts related to the 16-bit checksum are renamed and change type to u16. Furthermore, replace checksum calculation in exfat_load_upcase_table() with exfat_calc_checksum32(). Signed-off-by: Tetsuhiro Kohada Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon --- src/dir.c | 12 ++++++------ src/exfat_fs.h | 5 ++--- src/misc.c | 10 ++++------ src/nls.c | 19 +++++++------------ 4 files changed, 19 insertions(+), 27 deletions(-) diff --git a/src/dir.c b/src/dir.c index 2902d285bf20412af3a57b0e96a6768e49d6c5ac..de43534aa2997aa87994a9447f95578de9931258 100644 --- a/src/dir.c +++ b/src/dir.c @@ -491,7 +491,7 @@ int exfat_update_dir_chksum(struct inode *inode, struct exfat_chain *p_dir, int ret = 0; int i, num_entries; sector_t sector; - unsigned short chksum; + u16 chksum; struct exfat_dentry *ep, *fep; struct buffer_head *fbh, *bh; @@ -500,7 +500,7 @@ int exfat_update_dir_chksum(struct inode *inode, struct exfat_chain *p_dir, return -EIO; num_entries = fep->dentry.file.num_ext + 1; - chksum = exfat_calc_chksum_2byte(fep, DENTRY_SIZE, 0, CS_DIR_ENTRY); + chksum = exfat_calc_chksum16(fep, DENTRY_SIZE, 0, CS_DIR_ENTRY); for (i = 1; i < num_entries; i++) { ep = exfat_get_dentry(sb, p_dir, entry + i, &bh, NULL); @@ -508,7 +508,7 @@ int exfat_update_dir_chksum(struct inode *inode, struct exfat_chain *p_dir, ret = -EIO; goto release_fbh; } - chksum = exfat_calc_chksum_2byte(ep, DENTRY_SIZE, chksum, + chksum = exfat_calc_chksum16(ep, DENTRY_SIZE, chksum, CS_DEFAULT); brelse(bh); } @@ -593,8 +593,8 @@ void exfat_update_dir_chksum_with_entry_set(struct exfat_entry_set_cache *es) for (i = 0; i < es->num_entries; i++) { ep = exfat_get_dentry_cached(es, i); - chksum = exfat_calc_chksum_2byte(ep, DENTRY_SIZE, chksum, - chksum_type); + chksum = exfat_calc_chksum16(ep, DENTRY_SIZE, chksum, + chksum_type); chksum_type = CS_DEFAULT; } ep = exfat_get_dentry_cached(es, 0); @@ -1000,7 +1000,7 @@ int exfat_find_dir_entry(struct super_block *sb, struct exfat_inode_info *ei, } if (entry_type == TYPE_STREAM) { - unsigned short name_hash; + u16 name_hash; if (step != DIRENT_STEP_STRM) { step = DIRENT_STEP_FILE; diff --git a/src/exfat_fs.h b/src/exfat_fs.h index 8c2a70bfaa10d4743c46aad74254e363d4079c74..595f3117f4924893a07eba48b55ef3d7d6edbee6 100644 --- a/src/exfat_fs.h +++ b/src/exfat_fs.h @@ -137,7 +137,7 @@ struct exfat_dentry_namebuf { struct exfat_uni_name { /* +3 for null and for converting */ unsigned short name[MAX_NAME_LENGTH + 3]; - unsigned short name_hash; + u16 name_hash; unsigned char name_len; }; @@ -512,8 +512,7 @@ void exfat_get_entry_time(struct exfat_sb_info *sbi, struct timespec64 *ts, void exfat_truncate_atime(struct timespec64 *ts); void exfat_set_entry_time(struct exfat_sb_info *sbi, struct timespec64 *ts, u8 *tz, __le16 *time, __le16 *date, u8 *time_cs); -unsigned short exfat_calc_chksum_2byte(void *data, int len, - unsigned short chksum, int type); +u16 exfat_calc_chksum16(void *data, int len, u16 chksum, int type); u32 exfat_calc_chksum32(void *data, int len, u32 chksum, int type); void exfat_update_bh(struct super_block *sb, struct buffer_head *bh, int sync); void exfat_chain_set(struct exfat_chain *ec, unsigned int dir, diff --git a/src/misc.c b/src/misc.c index b82d2dd5bd7cb291ffe5ed5091c9214593c32a69..17d41f3d3709287f6654dd52bd540e3f60fee285 100644 --- a/src/misc.c +++ b/src/misc.c @@ -136,17 +136,15 @@ void exfat_truncate_atime(struct timespec64 *ts) ts->tv_nsec = 0; } -unsigned short exfat_calc_chksum_2byte(void *data, int len, - unsigned short chksum, int type) +u16 exfat_calc_chksum16(void *data, int len, u16 chksum, int type) { int i; - unsigned char *c = (unsigned char *)data; + u8 *c = (u8 *)data; for (i = 0; i < len; i++, c++) { - if (((i == 2) || (i == 3)) && (type == CS_DIR_ENTRY)) + if (unlikely(type == CS_DIR_ENTRY && (i == 2 || i == 3))) continue; - chksum = (((chksum & 1) << 15) | ((chksum & 0xFFFE) >> 1)) + - (unsigned short)*c; + chksum = ((chksum << 15) | (chksum >> 1)) + *c; } return chksum; } diff --git a/src/nls.c b/src/nls.c index 1ebda90cbdd7c81c507f662332a53eb52bf92606..19321773dd078a42f8c9659e15032502b33bddcd 100644 --- a/src/nls.c +++ b/src/nls.c @@ -527,7 +527,7 @@ static int exfat_utf8_to_utf16(struct super_block *sb, *uniname = '\0'; p_uniname->name_len = unilen; - p_uniname->name_hash = exfat_calc_chksum_2byte(upname, unilen << 1, 0, + p_uniname->name_hash = exfat_calc_chksum16(upname, unilen << 1, 0, CS_DEFAULT); if (p_lossy) @@ -623,7 +623,7 @@ static int exfat_nls_to_ucs2(struct super_block *sb, *uniname = '\0'; p_uniname->name_len = unilen; - p_uniname->name_hash = exfat_calc_chksum_2byte(upname, unilen << 1, 0, + p_uniname->name_hash = exfat_calc_chksum16(upname, unilen << 1, 0, CS_DEFAULT); if (p_lossy) @@ -655,7 +655,8 @@ static int exfat_load_upcase_table(struct super_block *sb, { struct exfat_sb_info *sbi = EXFAT_SB(sb); unsigned int sect_size = sb->s_blocksize; - unsigned int i, index = 0, checksum = 0; + unsigned int i, index = 0; + u32 chksum = 0; int ret; unsigned char skip = false; unsigned short *upcase_table; @@ -681,13 +682,6 @@ static int exfat_load_upcase_table(struct super_block *sb, for (i = 0; i < sect_size && index <= 0xFFFF; i += 2) { unsigned short uni = get_unaligned_le16(bh->b_data + i); - checksum = ((checksum & 1) ? 0x80000000 : 0) + - (checksum >> 1) + - *(((unsigned char *)bh->b_data) + i); - checksum = ((checksum & 1) ? 0x80000000 : 0) + - (checksum >> 1) + - *(((unsigned char *)bh->b_data) + (i + 1)); - if (skip) { index += uni; skip = false; @@ -701,13 +695,14 @@ static int exfat_load_upcase_table(struct super_block *sb, } } brelse(bh); + chksum = exfat_calc_chksum32(bh->b_data, i, chksum, CS_DEFAULT); } - if (index >= 0xFFFF && utbl_checksum == checksum) + if (index >= 0xFFFF && utbl_checksum == chksum) return 0; exfat_err(sb, "failed to load upcase table (idx : 0x%08x, chksum : 0x%08x, utbl_chksum : 0x%08x)", - index, checksum, utbl_checksum); + index, chksum, utbl_checksum); ret = -EINVAL; free_table: exfat_free_upcase_table(sbi); -- 2.31.1