f2fs: compress: fix to check zstd compress level correctly in mount option

f2fs only support to config zstd compress level w/ a positive number due
to layout design, but since commit e0c1b49f ("lib: zstd: Upgrade to
latest upstream zstd version 1.4.10"), zstd supports negative compress
level, so that zstd_min_clevel() may return a negative number, then w/
below mount option, .compress_level can be configed w/ a negative number,
which is not allowed to f2fs, let's add check condition to avoid it.

mount -o compress_algorithm=zstd:4294967295 /dev/sdx /mnt/f2fs

Fixes: 00e120b5 ("f2fs: assign default compression level")
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/super.c

@@ -627,7 +627,7 @@ static int f2fs_set_lz4hc_level(struct f2fs_sb_info *sbi, const char *str)
 #ifdef CONFIG_F2FS_FS_ZSTD
 static int f2fs_set_zstd_level(struct f2fs_sb_info *sbi, const char *str)
 {
-	unsigned int level;
+	int level;
 	int len = 4;
 
 	if (strlen(str) == len) {
@@ -641,9 +641,15 @@ static int f2fs_set_zstd_level(struct f2fs_sb_info *sbi, const char *str)
 		f2fs_info(sbi, "wrong format, e.g. <alg_name>:<compr_level>");
 		return -EINVAL;
 	}
-	if (kstrtouint(str + 1, 10, &level))
+	if (kstrtoint(str + 1, 10, &level))
 		return -EINVAL;
 
+	/* f2fs does not support negative compress level now */
+	if (level < 0) {
+		f2fs_info(sbi, "do not support negative compress level: %d", level);
+		return -ERANGE;
+	}
+
 	if (!f2fs_is_compress_level_valid(COMPRESS_ZSTD, level)) {
 		f2fs_info(sbi, "invalid zstd compress level: %d", level);
 		return -EINVAL;