ext4: remove redundant checks of s_encoding

Now that ext4 does not allow inodes with the casefold flag to be
instantiated when unsupported, it's unnecessary to repeatedly check for
support later on during random filesystem operations.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20230814182903.37267-3-ebiggers@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/hash.c

@@ -300,7 +300,7 @@ int ext4fs_dirhash(const struct inode *dir, const char *name, int len,
 	unsigned char *buff;
 	struct qstr qstr = {.name = name, .len = len };
 
-	if (len && IS_CASEFOLDED(dir) && um &&
+	if (len && IS_CASEFOLDED(dir) &&
 	   (!IS_ENCRYPTED(dir) || fscrypt_has_encryption_key(dir))) {
 		buff = kzalloc(sizeof(char) * PATH_MAX, GFP_KERNEL);
 		if (!buff)

fs/ext4/namei.c

@@ -1445,7 +1445,7 @@ int ext4_fname_setup_ci_filename(struct inode *dir, const struct qstr *iname,
 	struct dx_hash_info *hinfo = &name->hinfo;
 	int len;
 
-	if (!IS_CASEFOLDED(dir) || !dir->i_sb->s_encoding ||
+	if (!IS_CASEFOLDED(dir) ||
 	    (IS_ENCRYPTED(dir) && !fscrypt_has_encryption_key(dir))) {
 		cf_name->name = NULL;
 		return 0;
@@ -1496,7 +1496,7 @@ static bool ext4_match(struct inode *parent,
 #endif
 
 #if IS_ENABLED(CONFIG_UNICODE)
-	if (parent->i_sb->s_encoding && IS_CASEFOLDED(parent) &&
+	if (IS_CASEFOLDED(parent) &&
 	    (!IS_ENCRYPTED(parent) || fscrypt_has_encryption_key(parent))) {
 		if (fname->cf_name.name) {
 			struct qstr cf = {.name = fname->cf_name.name,
@@ -2393,7 +2393,7 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
 
 #if IS_ENABLED(CONFIG_UNICODE)
 	if (sb_has_strict_encoding(sb) && IS_CASEFOLDED(dir) &&
-	    sb->s_encoding && utf8_validate(sb->s_encoding, &dentry->d_name))
+	    utf8_validate(sb->s_encoding, &dentry->d_name))
 		return -EINVAL;
 #endif