[PATCH v2 1/2] staging: erofs: add requirements field in superblock

[PATCH v2 1/2] staging: erofs: add requirements field in superblock

[Gao Xiang]

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+
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
change log v2:
 - update printed message

 drivers/staging/erofs/erofs_fs.h | 13 ++++++++++---
 drivers/staging/erofs/super.c    | 17 +++++++++++++++++
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/erofs/erofs_fs.h b/drivers/staging/erofs/erofs_fs.h
index fa52898df006..8ddb2b3e7d39 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 */
 
 /*
  * erofs inode data mapping:
diff --git a/drivers/staging/erofs/super.c b/drivers/staging/erofs/super.c
index f580d4ef77a1..fdcf65b3e52d 100644
--- a/drivers/staging/erofs/super.c
+++ b/drivers/staging/erofs/super.c
@@ -71,6 +71,20 @@ 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);
+
+	/* 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 +118,9 @@ 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
-- 
2.17.1

Re: [PATCH v2 1/2] staging: erofs: add requirements field in superblock

[Chao Yu]

On 2019/6/11 10:42, Gao Xiang wrote:
> 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+
> Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>

Reviewed-by: Chao Yu <yuchao0@huawei.com>

Thanks,

[PATCH v3 1/2] staging: erofs: add requirements field in superblock

[Gao Xiang]

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>
---
change log v3:
 - record requirements in erofs_sb_info for runtime use as well;

change log v2:
 - update printed message

 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(-)

diff --git a/drivers/staging/erofs/erofs_fs.h b/drivers/staging/erofs/erofs_fs.h
index fa52898df006..8ddb2b3e7d39 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 */
 
 /*
  * erofs inode data mapping:
diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
index 911333cdeef4..fc732c86ecd8 100644
--- a/drivers/staging/erofs/internal.h
+++ b/drivers/staging/erofs/internal.h
@@ -115,6 +115,8 @@ 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 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
-- 
2.17.1

Re: [PATCH v3 1/2] staging: erofs: add requirements field in superblock

[Gao Xiang]

Hi Sasha,

On 2019/6/16 6:16, Sasha Levin wrote:
> Hi,
> 
> [This is an automated email]
> 
> This commit has been processed because it contains a "Fixes:" tag,
> fixing commit: ba2b77a82022 staging: erofs: add super block operations.
> 
> The bot has tested the following trees: v5.1.9, v4.19.50.
> 
> v5.1.9: Failed to apply! Possible dependencies:
>     Unable to calculate
> 
> v4.19.50: Failed to apply! Possible dependencies:
>     Unable to calculate
> 
> 
> How should we proceed with this patch?

I will manually make patches for v5.1.9 and v4.19.50
after it gets merged.

Thanks,
Gao Xiang

> 
> --
> Thanks,
> Sasha
> 

Re: [PATCH v3 1/2] staging: erofs: add requirements field in superblock

[Gao Xiang]

Hi Greg,

Sorry for annoying... Could you help merge these two fixes? Thanks in advance...
decompression inplace optimization needs these two patches and I will integrate
erofs decompression inplace optimization later for linux-next 5.3, and try to start 
making effort on moving to fs/ directory on kernel 5.4...

Thanks,
Gao Xiang

On 2019/6/13 16:35, Gao Xiang wrote:
> 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>
> ---
> change log v3:
>  - record requirements in erofs_sb_info for runtime use as well;
> 
> change log v2:
>  - update printed message
> 
>  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(-)
> 
> diff --git a/drivers/staging/erofs/erofs_fs.h b/drivers/staging/erofs/erofs_fs.h
> index fa52898df006..8ddb2b3e7d39 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 */
>  
>  /*
>   * erofs inode data mapping:
> diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
> index 911333cdeef4..fc732c86ecd8 100644
> --- a/drivers/staging/erofs/internal.h
> +++ b/drivers/staging/erofs/internal.h
> @@ -115,6 +115,8 @@ 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 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
> 

Re: [PATCH v3 1/2] staging: erofs: add requirements field in superblock

[Greg Kroah-Hartman]

On Sun, Jun 16, 2019 at 03:00:38PM +0800, Gao Xiang wrote:
> Hi Greg,
> 
> Sorry for annoying... Could you help merge these two fixes? Thanks in advance...

It was only 3 days, please give me at the very least, a week or so for
staging patches.

> decompression inplace optimization needs these two patches and I will integrate
> erofs decompression inplace optimization later for linux-next 5.3, and try to start 
> making effort on moving to fs/ directory on kernel 5.4...

You can always send follow-on patches, I apply them in the correct
order.  I will get to these next week, thanks.

greg k-h

Re: [PATCH v3 1/2] staging: erofs: add requirements field in superblock

[Gao Xiang]

On 2019/6/16 15:14, Greg Kroah-Hartman wrote:
> On Sun, Jun 16, 2019 at 03:00:38PM +0800, Gao Xiang wrote:
>> Hi Greg,
>>
>> Sorry for annoying... Could you help merge these two fixes? Thanks in advance...
> 
> It was only 3 days, please give me at the very least, a week or so for
> staging patches.
> 
>> decompression inplace optimization needs these two patches and I will integrate
>> erofs decompression inplace optimization later for linux-next 5.3, and try to start 
>> making effort on moving to fs/ directory on kernel 5.4...
> 
> You can always send follow-on patches, I apply them in the correct
> order.  I will get to these next week, thanks.

OK, I was actually just afraid of the appling order. I was thinking of merging
these two patches in advance since the new series has the dependency on these patches.

Thanks,
Gao Xiang

> 
> greg k-h
>