f2fs: compress: fix to disallow temp extension

This patch restricts to configure compress extension as format of:

 [filename + '.' + extension]

rather than:

 [filename + '.' + extension + (optional: '.' + temp extension)]

in order to avoid to enable compression incorrectly:

1. compress_extension=so
2. touch file.soa
3. touch file.so.tmp

Fixes: 4c8ff7095b ("f2fs: support data compression")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/namei.c

@@ -153,7 +153,8 @@ fail_drop:
 	return ERR_PTR(err);
 }
 
-static inline int is_extension_exist(const unsigned char *s, const char *sub)
+static inline int is_extension_exist(const unsigned char *s, const char *sub,
+						bool tmp_ext)
 {
 	size_t slen = strlen(s);
 	size_t sublen = strlen(sub);
@@ -169,6 +170,13 @@ static inline int is_extension_exist(const unsigned char *s, const char *sub)
 	if (slen < sublen + 2)
 		return 0;
 
+	if (!tmp_ext) {
+		/* file has no temp extension */
+		if (s[slen - sublen - 1] != '.')
+			return 0;
+		return !strncasecmp(s + slen - sublen, sub, sublen);
+	}
+
 	for (i = 1; i < slen - sublen; i++) {
 		if (s[i] != '.')
 			continue;
@@ -194,7 +202,7 @@ static inline void set_file_temperature(struct f2fs_sb_info *sbi, struct inode *
 	hot_count = sbi->raw_super->hot_ext_count;
 
 	for (i = 0; i < cold_count + hot_count; i++) {
-		if (is_extension_exist(name, extlist[i]))
+		if (is_extension_exist(name, extlist[i], true))
 			break;
 	}
 
@@ -295,7 +303,7 @@ static void set_compress_inode(struct f2fs_sb_info *sbi, struct inode *inode,
 	hot_count = sbi->raw_super->hot_ext_count;
 
 	for (i = cold_count; i < cold_count + hot_count; i++) {
-		if (is_extension_exist(name, extlist[i])) {
+		if (is_extension_exist(name, extlist[i], false)) {
 			up_read(&sbi->sb_lock);
 			return;
 		}
@@ -306,7 +314,7 @@ static void set_compress_inode(struct f2fs_sb_info *sbi, struct inode *inode,
 	ext = F2FS_OPTION(sbi).extensions;
 
 	for (i = 0; i < ext_cnt; i++) {
-		if (!is_extension_exist(name, ext[i]))
+		if (!is_extension_exist(name, ext[i], false))
 			continue;
 
 		set_compress_context(inode);