[PATCH 5.15 168/244] f2fs: compress: fix to avoid redundant compress extension

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

5.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chao Yu <chao@xxxxxxxxxx>

[ Upstream commit 7e1b150fece033703a824df1bbc03df091ea53cc ]

With below script, redundant compress extension will be parsed and added
by parse_options(), because parse_options() doesn't check whether the
extension is existed or not, fix it.

1. mount -t f2fs -o compress_extension=so /dev/vdb /mnt/f2fs
2. mount -t f2fs -o remount,compress_extension=so /mnt/f2fs
3. mount|grep f2fs

/dev/vdb on /mnt/f2fs type f2fs (...,compress_extension=so,compress_extension=so,...)

Fixes: 4c8ff7095bef ("f2fs: support data compression")
Fixes: 151b1982be5d ("f2fs: compress: add nocompress extensions support")
Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/f2fs/super.c |   33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -540,6 +540,29 @@ static int f2fs_set_test_dummy_encryptio
 }
 
 #ifdef CONFIG_F2FS_FS_COMPRESSION
+static bool is_compress_extension_exist(struct f2fs_sb_info *sbi,
+					const char *new_ext, bool is_ext)
+{
+	unsigned char (*ext)[F2FS_EXTENSION_LEN];
+	int ext_cnt;
+	int i;
+
+	if (is_ext) {
+		ext = F2FS_OPTION(sbi).extensions;
+		ext_cnt = F2FS_OPTION(sbi).compress_ext_cnt;
+	} else {
+		ext = F2FS_OPTION(sbi).noextensions;
+		ext_cnt = F2FS_OPTION(sbi).nocompress_ext_cnt;
+	}
+
+	for (i = 0; i < ext_cnt; i++) {
+		if (!strcasecmp(new_ext, ext[i]))
+			return true;
+	}
+
+	return false;
+}
+
 /*
  * 1. The same extension name cannot not appear in both compress and non-compress extension
  * at the same time.
@@ -1154,6 +1177,11 @@ static int parse_options(struct super_bl
 				return -EINVAL;
 			}
 
+			if (is_compress_extension_exist(sbi, name, true)) {
+				kfree(name);
+				break;
+			}
+
 			strcpy(ext[ext_cnt], name);
 			F2FS_OPTION(sbi).compress_ext_cnt++;
 			kfree(name);
@@ -1178,6 +1206,11 @@ static int parse_options(struct super_bl
 				return -EINVAL;
 			}
 
+			if (is_compress_extension_exist(sbi, name, false)) {
+				kfree(name);
+				break;
+			}
+
 			strcpy(noext[noext_cnt], name);
 			F2FS_OPTION(sbi).nocompress_ext_cnt++;
 			kfree(name);