From 5875bf287d95314c58add01184f361cc5aa38429 Mon Sep 17 00:00:00 2001
From: Tetsuhiro Kohada <kohada.t2@gmail.com>
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 <kohada.t2@gmail.com>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
---
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