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Commit e6153918 authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Theodore Ts'o
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ext4: change on-disk layout to support extended metadata checksumming 



Define flags and change structure definitions to allow checksumming of
ext4 metadata.

Signed-off-by: default avatarDarrick J. Wong <djwong@us.ibm.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent f8489128

fs/ext4/ext4.h

+39 −8
Original line number Diff line number Diff line
@@ -298,7 +298,9 @@ struct ext4_group_desc 
	__le16	bg_free_inodes_count_lo;/* Free inodes count */

	__le16	bg_used_dirs_count_lo;	/* Directories count */

	__le16	bg_flags;		/* EXT4_BG_flags (INODE_UNINIT, etc) */

	__u32	bg_reserved[2];		/* Likely block/inode bitmap checksum */

	__le32  bg_exclude_bitmap_lo;   /* Exclude bitmap for snapshots */

	__le16  bg_block_bitmap_csum_lo;/* crc32c(s_uuid+grp_num+bbitmap) LE */

	__le16  bg_inode_bitmap_csum_lo;/* crc32c(s_uuid+grp_num+ibitmap) LE */

	__le16  bg_itable_unused_lo;	/* Unused inodes count */

	__le16  bg_checksum;		/* crc16(sb_uuid+group+desc) */

	__le32	bg_block_bitmap_hi;	/* Blocks bitmap block MSB */
@@ -308,7 +310,10 @@ struct ext4_group_desc 
	__le16	bg_free_inodes_count_hi;/* Free inodes count MSB */

	__le16	bg_used_dirs_count_hi;	/* Directories count MSB */

	__le16  bg_itable_unused_hi;    /* Unused inodes count MSB */

	__u32	bg_reserved2[3];

	__le32  bg_exclude_bitmap_hi;   /* Exclude bitmap block MSB */

	__le16  bg_block_bitmap_csum_hi;/* crc32c(s_uuid+grp_num+bbitmap) BE */

	__le16  bg_inode_bitmap_csum_hi;/* crc32c(s_uuid+grp_num+ibitmap) BE */

	__u32   bg_reserved;

};



/*
@@ -650,7 +655,8 @@ struct ext4_inode { 
			__le16	l_i_file_acl_high;

			__le16	l_i_uid_high;	/* these 2 fields */

			__le16	l_i_gid_high;	/* were reserved2[0] */

			__u32	l_i_reserved2;

			__le16	l_i_checksum_lo;/* crc32c(uuid+inum+inode) LE */

			__le16	l_i_reserved;

		} linux2;

		struct {

			__le16	h_i_reserved1;	/* Obsoleted fragment number/size which are removed in ext4 */
@@ -666,7 +672,7 @@ struct ext4_inode { 
		} masix2;

	} osd2;				/* OS dependent 2 */

	__le16	i_extra_isize;

	__le16	i_pad1;

	__le16	i_checksum_hi;	/* crc32c(uuid+inum+inode) BE */

	__le32  i_ctime_extra;  /* extra Change time      (nsec << 2 | epoch) */

	__le32  i_mtime_extra;  /* extra Modification time(nsec << 2 | epoch) */

	__le32  i_atime_extra;  /* extra Access time      (nsec << 2 | epoch) */
@@ -768,7 +774,7 @@ do { \ 
#define i_gid_low	i_gid

#define i_uid_high	osd2.linux2.l_i_uid_high

#define i_gid_high	osd2.linux2.l_i_gid_high

#define i_reserved2	osd2.linux2.l_i_reserved2

#define i_checksum_lo	osd2.linux2.l_i_checksum_lo



#elif defined(__GNU__)
@@ -1001,6 +1007,9 @@ extern void ext4_set_bits(void *bm, int cur, int len); 
#define EXT4_ERRORS_PANIC		3	/* Panic */

#define EXT4_ERRORS_DEFAULT		EXT4_ERRORS_CONTINUE



/* Metadata checksum algorithm codes */

#define EXT4_CRC32C_CHKSUM		1



/*

 * Structure of the super block

 */
@@ -1087,7 +1096,7 @@ struct ext4_super_block { 
	__le64  s_mmp_block;            /* Block for multi-mount protection */

	__le32  s_raid_stripe_width;    /* blocks on all data disks (N*stride)*/

	__u8	s_log_groups_per_flex;  /* FLEX_BG group size */

	__u8	s_reserved_char_pad;

	__u8	s_checksum_type;	/* metadata checksum algorithm used */

	__le16  s_reserved_pad;

	__le64	s_kbytes_written;	/* nr of lifetime kilobytes written */

	__le32	s_snapshot_inum;	/* Inode number of active snapshot */
@@ -1113,7 +1122,8 @@ struct ext4_super_block { 
	__le32	s_usr_quota_inum;	/* inode for tracking user quota */

	__le32	s_grp_quota_inum;	/* inode for tracking group quota */

	__le32	s_overhead_clusters;	/* overhead blocks/clusters in fs */

	__le32  s_reserved[109];        /* Padding to the end of the block */

	__le32	s_reserved[108];	/* Padding to the end of the block */

	__le32	s_checksum;		/* crc32c(superblock) */

};



#define EXT4_S_ERR_LEN (EXT4_S_ERR_END - EXT4_S_ERR_START)
@@ -1414,6 +1424,12 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei) 
#define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE	0x0040

#define EXT4_FEATURE_RO_COMPAT_QUOTA		0x0100

#define EXT4_FEATURE_RO_COMPAT_BIGALLOC		0x0200

/*

 * METADATA_CSUM also enables group descriptor checksums (GDT_CSUM).  When

 * METADATA_CSUM is set, group descriptor checksums use the same algorithm as

 * all other data structures' checksums.  However, the METADATA_CSUM and

 * GDT_CSUM bits are mutually exclusive.

 */

#define EXT4_FEATURE_RO_COMPAT_METADATA_CSUM	0x0400



#define EXT4_FEATURE_INCOMPAT_COMPRESSION	0x0001
@@ -1526,6 +1542,18 @@ struct ext4_dir_entry_2 { 
	char	name[EXT4_NAME_LEN];	/* File name */

};



/*

 * This is a bogus directory entry at the end of each leaf block that

 * records checksums.

 */

struct ext4_dir_entry_tail {

	__le32	det_reserved_zero1;	/* Pretend to be unused */

	__le16	det_rec_len;		/* 12 */

	__u8	det_reserved_zero2;	/* Zero name length */

	__u8	det_reserved_ft;	/* 0xDE, fake file type */

	__le32	det_checksum;		/* crc32c(uuid+inum+dirblock) */

};



/*

 * Ext4 directory file types.  Only the low 3 bits are used.  The

 * other bits are reserved for now.
@@ -1541,6 +1569,8 @@ struct ext4_dir_entry_2 { 


#define EXT4_FT_MAX		8



#define EXT4_FT_DIR_CSUM	0xDE



/*

 * EXT4_DIR_PAD defines the directory entries boundaries

 *
@@ -1741,7 +1771,8 @@ struct mmp_struct { 
	__le16	mmp_check_interval;



	__le16	mmp_pad1;

	__le32	mmp_pad2[227];

	__le32	mmp_pad2[226];

	__le32	mmp_checksum;		/* crc32c(uuid+mmp_block) */

};



/* arguments passed to the mmp thread */

fs/ext4/ext4_extents.h

+13 −0
Original line number Diff line number Diff line
@@ -63,8 +63,21 @@ 
 * ext4_inode has i_block array (60 bytes total).

 * The first 12 bytes store ext4_extent_header;

 * the remainder stores an array of ext4_extent.

 * For non-inode extent blocks, ext4_extent_tail

 * follows the array.

 */



/*

 * This is the extent tail on-disk structure.

 * All other extent structures are 12 bytes long.  It turns out that

 * block_size % 12 >= 4 for at least all powers of 2 greater than 512, which

 * covers all valid ext4 block sizes.  Therefore, this tail structure can be

 * crammed into the end of the block without having to rebalance the tree.

 */

struct ext4_extent_tail {

	__le32	et_checksum;	/* crc32c(uuid+inum+extent_block) */

};



/*

 * This is the extent on-disk structure.

 * It's used at the bottom of the tree.

fs/ext4/namei.c

+8 −0
Original line number Diff line number Diff line
@@ -145,6 +145,14 @@ struct dx_map_entry 
	u16 size;

};



/*

 * This goes at the end of each htree block.

 */

struct dx_tail {

	u32 dt_reserved;

	__le32 dt_checksum;	/* crc32c(uuid+inum+dirblock) */

};



static inline ext4_lblk_t dx_get_block(struct dx_entry *entry);

static void dx_set_block(struct dx_entry *entry, ext4_lblk_t value);

static inline unsigned dx_get_hash(struct dx_entry *entry);

fs/ext4/xattr.h

+3 −1
Original line number Diff line number Diff line
@@ -27,7 +27,9 @@ struct ext4_xattr_header { 
	__le32	h_refcount;	/* reference count */

	__le32	h_blocks;	/* number of disk blocks used */

	__le32	h_hash;		/* hash value of all attributes */

	__u32	h_reserved[4];	/* zero right now */

	__le32	h_checksum;	/* crc32c(uuid+id+xattrblock) */

				/* id = inum if refcount=1, blknum otherwise */

	__u32	h_reserved[3];	/* zero right now */

};



struct ext4_xattr_ibody_header {