libfs: remove redundant checks of s_encoding

Now that neither ext4 nor f2fs allows 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/20230814182903.37267-4-ebiggers@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/libfs.c

@@ -1381,16 +1381,6 @@ bool is_empty_dir_inode(struct inode *inode)
 }
 
 #if IS_ENABLED(CONFIG_UNICODE)
-/*
- * Determine if the name of a dentry should be casefolded.
- *
- * Return: if names will need casefolding
- */
-static bool needs_casefold(const struct inode *dir)
-{
-	return IS_CASEFOLDED(dir) && dir->i_sb->s_encoding;
-}
-
 /**
  * generic_ci_d_compare - generic d_compare implementation for casefolding filesystems
  * @dentry:	dentry whose name we are checking against
@@ -1411,7 +1401,7 @@ static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
 	char strbuf[DNAME_INLINE_LEN];
 	int ret;
 
-	if (!dir || !needs_casefold(dir))
+	if (!dir || !IS_CASEFOLDED(dir))
 		goto fallback;
 	/*
 	 * If the dentry name is stored in-line, then it may be concurrently
@@ -1453,7 +1443,7 @@ static int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
 	const struct unicode_map *um = sb->s_encoding;
 	int ret = 0;
 
-	if (!dir || !needs_casefold(dir))
+	if (!dir || !IS_CASEFOLDED(dir))
 		return 0;
 
 	ret = utf8_casefold_hash(um, dentry, str);