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authorGao Xiang <gaoxiang25@huawei.com>2019-06-13 16:35:41 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-06-25 11:36:01 +0800
commit64e370233a0781aa0954ed4079e90d0bdb748b0e (patch)
tree13b178bc4945406edaa0a27e9277860ce5f590da
parente6803ce36d496bc8173e3a32f5d396ead5afac02 (diff)
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staging: erofs: add requirements field in superblock
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>
-rw-r--r--drivers/staging/erofs/erofs_fs.h13
-rw-r--r--drivers/staging/erofs/internal.h2
-rw-r--r--drivers/staging/erofs/super.c19
3 files changed, 31 insertions, 3 deletions
diff --git a/drivers/staging/erofs/erofs_fs.h b/drivers/staging/erofs/erofs_fs.h
index 2f8e2bf70941..7677da889f12 100644
--- 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 */
#define __EROFS_BIT(_prefix, _cur, _pre) enum { \
_prefix ## _cur ## _BIT = _prefix ## _pre ## _BIT + \
diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
index 58d8cbc3f921..8ce37091db20 100644
--- a/drivers/staging/erofs/internal.h
+++ b/drivers/staging/erofs/internal.h
@@ -111,6 +111,8 @@ 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;
diff --git a/drivers/staging/erofs/super.c b/drivers/staging/erofs/super.c
index b0583cdb079a..b49ebdf6ebda 100644
--- a/drivers/staging/erofs/super.c
+++ b/drivers/staging/erofs/super.c
@@ -75,6 +75,22 @@ static void destroy_inode(struct inode *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;
@@ -108,6 +124,9 @@ 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