[PATCH 0/4] Fixes for exfat driver

[Pali Rohár]

This patch series contains small fixes for exfat driver. It removes
conversion from UTF-16 to UTF-16 at two places where it is not needed
and fixes discard support.

Patches are also in my exfat branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pali/linux.git/log/?h=exfat

Pali Rohár (4):
exfat: Simplify exfat_utf8_d_hash() for code points above U+FFFF
exfat: Simplify exfat_utf8_d_cmp() for code points above U+FFFF
exfat: Remove unused functions exfat_high_surrogate() and
exfat_low_surrogate()
exfat: Fix discard support

fs/exfat/exfat_fs.h | 2 --
fs/exfat/namei.c | 19 ++++---------------
fs/exfat/nls.c | 13 -------------
fs/exfat/super.c | 5 +++--
4 files changed, 7 insertions(+), 32 deletions(-)

[Pali Rohár]

Function partial_name_hash() takes long type value into which can be stored
one Unicode code point. Therefore conversion from UTF-32 to UTF-16 is not
needed.

Signed-off-by: Pali Rohár <***@kernel.org>
---
fs/exfat/namei.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c
index a8681d91f569..e0ec4ff366f5 100644
--- a/fs/exfat/namei.c
+++ b/fs/exfat/namei.c
@@ -147,16 +147,10 @@ static int exfat_utf8_d_hash(const struct dentry *dentry, struct qstr *qstr)
return charlen;

/*
- * Convert to UTF-16: code points above U+FFFF are encoded as
- * surrogate pairs.
* exfat_toupper() works only for code points up to the U+FFFF.
*/
- if (u > 0xFFFF) {
- hash = partial_name_hash(exfat_high_surrogate(u), hash);
- hash = partial_name_hash(exfat_low_surrogate(u), hash);
- } else {
- hash = partial_name_hash(exfat_toupper(sb, u), hash);
- }
+ hash = partial_name_hash(u <= 0xFFFF ? exfat_toupper(sb, u) : u,
+ hash);
}

qstr->hash = end_name_hash(hash);

[Al Viro]

Post by Pali Rohár
Function partial_name_hash() takes long type value into which can be stored
one Unicode code point. Therefore conversion from UTF-32 to UTF-16 is not
needed.

Hmm... You might want to update the comment in stringhash.h...

[Pali Rohár]

If two Unicode code points represented in UTF-16 are different then also
their UTF-32 representation must be different. Therefore conversion from
UTF-32 to UTF-16 is not needed.

Signed-off-by: Pali Rohár <***@kernel.org>
---
fs/exfat/namei.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c
index e0ec4ff366f5..f07cab5fcd28 100644
--- a/fs/exfat/namei.c
+++ b/fs/exfat/namei.c
@@ -179,14 +179,9 @@ static int exfat_utf8_d_cmp(const struct dentry *dentry, unsigned int len,
if (u_a <= 0xFFFF && u_b <= 0xFFFF) {
if (exfat_toupper(sb, u_a) != exfat_toupper(sb, u_b))
return 1;
- } else if (u_a > 0xFFFF && u_b > 0xFFFF) {
- if (exfat_low_surrogate(u_a) !=
- exfat_low_surrogate(u_b) ||
- exfat_high_surrogate(u_a) !=
- exfat_high_surrogate(u_b))
- return 1;
} else {
- return 1;
+ if (u_a != u_b)
+ return 1;
}
}

[Pali Rohár]

After applying previous two patches, these functions are not used anymore.

Signed-off-by: Pali Rohár <***@kernel.org>
---
fs/exfat/exfat_fs.h | 2 --
fs/exfat/nls.c | 13 -------------
2 files changed, 15 deletions(-)

diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index 67d4e46fb810..8a176a803206 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -492,8 +492,6 @@ int exfat_nls_to_utf16(struct super_block *sb,
struct exfat_uni_name *uniname, int *p_lossy);
int exfat_create_upcase_table(struct super_block *sb);
void exfat_free_upcase_table(struct exfat_sb_info *sbi);
-unsigned short exfat_high_surrogate(unicode_t u);
-unsigned short exfat_low_surrogate(unicode_t u);

/* exfat/misc.c */
void __exfat_fs_error(struct super_block *sb, int report, const char *fmt, ...)
diff --git a/fs/exfat/nls.c b/fs/exfat/nls.c
index 6d1c3ae130ff..e3a9f5e08f68 100644
--- a/fs/exfat/nls.c
+++ b/fs/exfat/nls.c
@@ -537,22 +537,9 @@ static int exfat_utf8_to_utf16(struct super_block *sb,
return unilen;
}

-#define PLANE_SIZE 0x00010000
#define SURROGATE_MASK 0xfffff800
#define SURROGATE_PAIR 0x0000d800
#define SURROGATE_LOW 0x00000400
-#define SURROGATE_BITS 0x000003ff
-
-unsigned short exfat_high_surrogate(unicode_t u)
-{
- return ((u - PLANE_SIZE) >> 10) + SURROGATE_PAIR;
-}
-
-unsigned short exfat_low_surrogate(unicode_t u)
-{
- return ((u - PLANE_SIZE) & SURROGATE_BITS) | SURROGATE_PAIR |
- SURROGATE_LOW;
-}

static int __exfat_utf16_to_nls(struct super_block *sb,
struct exfat_uni_name *p_uniname, unsigned char *p_cstring,

[Pali Rohár]

Discard support was always unconditionally disabled. Now it is disabled
only in the case when blk_queue_discard() returns false.

Signed-off-by: Pali Rohár <***@kernel.org>
---
fs/exfat/super.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/exfat/super.c b/fs/exfat/super.c
index 16ed202ef527..30e914ad17b5 100644
--- a/fs/exfat/super.c
+++ b/fs/exfat/super.c
@@ -531,10 +531,11 @@ static int exfat_fill_super(struct super_block *sb, struct fs_context *fc)
if (opts->discard) {
struct request_queue *q = bdev_get_queue(sb->s_bdev);

- if (!blk_queue_discard(q))
+ if (!blk_queue_discard(q)) {
exfat_msg(sb, KERN_WARNING,
"mounting with \"discard\" option, but the device does not support discard");
- opts->discard = 0;
+ opts->discard = 0;
+ }
}

sb->s_flags |= SB_NODIRATIME;

[Namjae Jeon]

Post by Pali Rohár
This patch series contains small fixes for exfat driver. It removes
conversion from UTF-16 to UTF-16 at two places where it is not needed and
fixes discard support.

Looks good to me.
Acked-by: Namjae Jeon <***@samsung.com>

Hi Al,

Could you please push these patches into your #for-next ?
Thanks!

Post by Pali Rohár
https://git.kernel.org/pub/scm/linux/kernel/git/pali/linux.git/log/?h=exfa
t
exfat: Simplify exfat_utf8_d_hash() for code points above U+FFFF
exfat: Simplify exfat_utf8_d_cmp() for code points above U+FFFF
exfat: Remove unused functions exfat_high_surrogate() and
exfat_low_surrogate()
exfat: Fix discard support
fs/exfat/exfat_fs.h | 2 --
fs/exfat/namei.c | 19 ++++---------------
fs/exfat/nls.c | 13 -------------
fs/exfat/super.c | 5 +++--
4 files changed, 7 insertions(+), 32 deletions(-)
--
2.20.1