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>

diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
index 2902d285bf20412af3a57b0e96a6768e49d6c5ac..de43534aa2997aa87994a9447f95578de9931258 100644 (file)
--- a/fs/exfat/dir.c
+++ b/fs/exfat/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 @@ rewind:
                        }
 
                        if (entry_type == TYPE_STREAM) {
-                               unsigned short name_hash;
+                               u16 name_hash;
 
                                if (step != DIRENT_STEP_STRM) {
                                        step = DIRENT_STEP_FILE;

diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index 8c2a70bfaa10d4743c46aad74254e363d4079c74..595f3117f4924893a07eba48b55ef3d7d6edbee6 100644 (file)
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/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/fs/exfat/misc.c b/fs/exfat/misc.c
index b82d2dd5bd7cb291ffe5ed5091c9214593c32a69..17d41f3d3709287f6654dd52bd540e3f60fee285 100644 (file)
--- a/fs/exfat/misc.c
+++ b/fs/exfat/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/fs/exfat/nls.c b/fs/exfat/nls.c
index 1ebda90cbdd7c81c507f662332a53eb52bf92606..19321773dd078a42f8c9659e15032502b33bddcd 100644 (file)
--- a/fs/exfat/nls.c
+++ b/fs/exfat/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);