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Commit 64e37023 authored by Gao Xiang's avatar Gao Xiang Committed by Greg Kroah-Hartman
Browse files

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: ba2b77a8 ("staging: erofs: add super block operations")
Cc: <stable@vger.kernel.org> # 4.19+
Reviewed-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarGao Xiang <gaoxiang25@huawei.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e6803ce3

drivers/staging/erofs/erofs_fs.h

+10 −3
Original line number Diff line number Diff line
@@ -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 + \

drivers/staging/erofs/internal.h

+2 −0
Original line number Diff line number Diff line
@@ -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;

drivers/staging/erofs/super.c

+19 −0
Original line number Diff line number Diff line
@@ -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