f2fs: optimize case-insensitive lookups

This patch ports below casefold enhancement patch from ext4 to f2fs

commit 3ae72562 ("ext4: optimize case-insensitive lookups")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/dir.c

@@ -112,13 +112,17 @@ static struct f2fs_dir_entry *find_in_block(struct inode *dir,
  * doesn't match or less than zero on error.
  */
 int f2fs_ci_compare(const struct inode *parent, const struct qstr *name,
-		    const struct qstr *entry)
+				const struct qstr *entry, bool quick)
 {
 	const struct f2fs_sb_info *sbi = F2FS_SB(parent->i_sb);
 	const struct unicode_map *um = sbi->s_encoding;
 	int ret;
 
-	ret = utf8_strncasecmp(um, name, entry);
+	if (quick)
+		ret = utf8_strncasecmp_folded(um, name, entry);
+	else
+		ret = utf8_strncasecmp(um, name, entry);
+
 	if (ret < 0) {
 		/* Handle invalid character sequence as either an error
 		 * or as an opaque byte sequence.
@@ -134,11 +138,36 @@ int f2fs_ci_compare(const struct inode *parent, const struct qstr *name,
 
 	return ret;
 }
+
+static void f2fs_fname_setup_ci_filename(struct inode *dir,
+					const struct qstr *iname,
+					struct fscrypt_str *cf_name)
+{
+	struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
+
+	if (!IS_CASEFOLDED(dir)) {
+		cf_name->name = NULL;
+		return;
+	}
+
+	cf_name->name = f2fs_kmalloc(sbi, F2FS_NAME_LEN, GFP_NOFS);
+	if (!cf_name->name)
+		return;
+
+	cf_name->len = utf8_casefold(sbi->s_encoding,
+					iname, cf_name->name,
+					F2FS_NAME_LEN);
+	if ((int)cf_name->len <= 0) {
+		kvfree(cf_name->name);
+		cf_name->name = NULL;
+	}
+}
 #endif
 
 static inline bool f2fs_match_name(struct f2fs_dentry_ptr *d,
 					struct f2fs_dir_entry *de,
 					struct fscrypt_name *fname,
+					struct fscrypt_str *cf_str,
 					unsigned long bit_pos,
 					f2fs_hash_t namehash)
 {
@@ -155,8 +184,15 @@ static inline bool f2fs_match_name(struct f2fs_dentry_ptr *d,
 	entry.name = d->filename[bit_pos];
 	entry.len = de->name_len;
 
-	if (sbi->s_encoding && IS_CASEFOLDED(parent))
-		return !f2fs_ci_compare(parent, fname->usr_fname, &entry);
+	if (sbi->s_encoding && IS_CASEFOLDED(parent)) {
+		if (cf_str->name) {
+			struct qstr cf = {.name = cf_str->name,
+					  .len = cf_str->len};
+			return !f2fs_ci_compare(parent, &cf, &entry, true);
+		}
+		return !f2fs_ci_compare(parent, fname->usr_fname, &entry,
+					false);
+	}
 #endif
 	if (fscrypt_match_name(fname, d->filename[bit_pos],
 				le16_to_cpu(de->name_len)))
@@ -169,9 +205,14 @@ struct f2fs_dir_entry *f2fs_find_target_dentry(struct fscrypt_name *fname,
 			struct f2fs_dentry_ptr *d)
 {
 	struct f2fs_dir_entry *de;
+	struct fscrypt_str cf_str = { .name = NULL, .len = 0 };
 	unsigned long bit_pos = 0;
 	int max_len = 0;
 
+#ifdef CONFIG_UNICODE
+	f2fs_fname_setup_ci_filename(d->inode, fname->usr_fname, &cf_str);
+#endif
+
 	if (max_slots)
 		*max_slots = 0;
 	while (bit_pos < d->max) {
@@ -188,7 +229,7 @@ struct f2fs_dir_entry *f2fs_find_target_dentry(struct fscrypt_name *fname,
 			continue;
 		}
 
-		if (f2fs_match_name(d, de, fname, bit_pos, namehash))
+		if (f2fs_match_name(d, de, fname, &cf_str, bit_pos, namehash))
 			goto found;
 
 		if (max_slots && max_len > *max_slots)
@@ -202,6 +243,10 @@ struct f2fs_dir_entry *f2fs_find_target_dentry(struct fscrypt_name *fname,
 found:
 	if (max_slots && max_len > *max_slots)
 		*max_slots = max_len;
+
+#ifdef CONFIG_UNICODE
+	kvfree(cf_str.name);
+#endif
 	return de;
 }
 
@@ -1025,7 +1070,7 @@ static int f2fs_d_compare(const struct dentry *dentry, unsigned int len,
 		return memcmp(str, name, len);
 	}
 
-	return f2fs_ci_compare(dentry->d_parent->d_inode, name, &qstr);
+	return f2fs_ci_compare(dentry->d_parent->d_inode, name, &qstr, false);
 }
 
 static int f2fs_d_hash(const struct dentry *dentry, struct qstr *str)

fs/f2fs/f2fs.h

@@ -2941,7 +2941,8 @@ struct dentry *f2fs_get_parent(struct dentry *child);
 
 extern int f2fs_ci_compare(const struct inode *parent,
 			   const struct qstr *name,
-			   const struct qstr *entry);
+			   const struct qstr *entry,
+			   bool quick);
 
 /*
  * dir.c