Patch "f2fs: compress: fix to avoid redundant compress extension" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    f2fs: compress: fix to avoid redundant compress extension

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     f2fs-compress-fix-to-avoid-redundant-compress-extens.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 5c3751456274b97529ba7ac9604c690797d021ae
Author: Chao Yu <chao@xxxxxxxxxx>
Date:   Mon Aug 28 22:04:17 2023 +0800

    f2fs: compress: fix to avoid redundant compress extension
    
    [ 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>

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index daae61df66ffa..e40bc0aeb7fb5 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -509,6 +509,29 @@ static int f2fs_set_test_dummy_encryption(struct super_block *sb,
 }
 
 #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.
@@ -1112,6 +1135,11 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
 				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);
@@ -1136,6 +1164,11 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
 				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);