From: Gao Xiang gaoxiang25@huawei.com
commit 5efe5137f05bbb4688890620934538c005e7d1d6 upstream.
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: stable@vger.kernel.org # 4.19+ Reviewed-by: Chao Yu yuchao0@huawei.com Signed-off-by: Gao Xiang gaoxiang25@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/staging/erofs/erofs_fs.h | 13 ++++++++++--- drivers/staging/erofs/internal.h | 2 ++ drivers/staging/erofs/super.c | 19 +++++++++++++++++++ 3 files changed, 31 insertions(+), 3 deletions(-)
--- a/drivers/staging/erofs/erofs_fs.h +++ b/drivers/staging/erofs/erofs_fs.h @@ -17,10 +17,16 @@ #define EROFS_SUPER_MAGIC_V1 0xE0F5E1E2 #define EROFS_SUPER_OFFSET 1024
+/* + * Any bits that aren't in EROFS_ALL_REQUIREMENTS should be + * incompatible with this kernel version. + */ +#define EROFS_ALL_REQUIREMENTS 0 + struct erofs_super_block { /* 0 */__le32 magic; /* in the little endian */ /* 4 */__le32 checksum; /* crc32c(super_block) */ -/* 8 */__le32 features; +/* 8 */__le32 features; /* (aka. feature_compat) */ /* 12 */__u8 blkszbits; /* support block_size == PAGE_SIZE only */ /* 13 */__u8 reserved;
@@ -34,9 +40,10 @@ struct erofs_super_block { /* 44 */__le32 xattr_blkaddr; /* 48 */__u8 uuid[16]; /* 128-bit uuid for volume */ /* 64 */__u8 volume_name[16]; /* volume name */ +/* 80 */__le32 requirements; /* (aka. feature_incompat) */
-/* 80 */__u8 reserved2[48]; /* 128 bytes */ -} __packed; +/* 84 */__u8 reserved2[44]; +} __packed; /* 128 bytes */
/* * erofs inode data mapping: --- a/drivers/staging/erofs/internal.h +++ b/drivers/staging/erofs/internal.h @@ -114,6 +114,8 @@ struct erofs_sb_info {
u8 uuid[16]; /* 128-bit uuid for volume */ u8 volume_name[16]; /* volume name */ + u32 requirements; + char *dev_name;
unsigned int mount_opt; --- a/drivers/staging/erofs/super.c +++ b/drivers/staging/erofs/super.c @@ -76,6 +76,22 @@ static void destroy_inode(struct inode * call_rcu(&inode->i_rcu, i_callback); }
+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; @@ -109,6 +125,9 @@ static int superblock_read(struct super_ 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