From 5efe5137f05bbb4688890620934538c005e7d1d6 Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Thu, 13 Jun 2019 16:35:41 +0800 Subject: staging: erofs: add requirements field in superblock There are some backward incompatible features pending for months, mainly due to on-disk format expensions. However, we should ensure that it cannot be mounted with old kernels. Otherwise, it will causes unexpected behaviors. Fixes: ba2b77a82022 ("staging: erofs: add super block operations") Cc: # 4.19+ Reviewed-by: Chao Yu Signed-off-by: Gao Xiang Signed-off-by: Greg Kroah-Hartman --- drivers/staging/erofs/super.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'drivers/staging/erofs/super.c') diff --git a/drivers/staging/erofs/super.c b/drivers/staging/erofs/super.c index f580d4ef77a1..cadbcc11702a 100644 --- a/drivers/staging/erofs/super.c +++ b/drivers/staging/erofs/super.c @@ -71,6 +71,22 @@ static void free_inode(struct inode *inode) kmem_cache_free(erofs_inode_cachep, vi); } +static bool check_layout_compatibility(struct super_block *sb, + struct erofs_super_block *layout) +{ + const unsigned int requirements = le32_to_cpu(layout->requirements); + + EROFS_SB(sb)->requirements = requirements; + + /* check if current kernel meets all mandatory requirements */ + if (requirements & (~EROFS_ALL_REQUIREMENTS)) { + errln("unidentified requirements %x, please upgrade kernel version", + requirements & ~EROFS_ALL_REQUIREMENTS); + return false; + } + return true; +} + static int superblock_read(struct super_block *sb) { struct erofs_sb_info *sbi; @@ -104,6 +120,9 @@ static int superblock_read(struct super_block *sb) goto out; } + if (!check_layout_compatibility(sb, layout)) + goto out; + sbi->blocks = le32_to_cpu(layout->blocks); sbi->meta_blkaddr = le32_to_cpu(layout->meta_blkaddr); #ifdef CONFIG_EROFS_FS_XATTR -- cgit v1.2.3