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jbd2: change disk layout for metadata checksumming

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Define flags and allocate space in on-disk journal structures to support
checksumming of journal metadata.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Darrick J. Wong 2012-05-22 22:43:41 -04:00 • committed by Theodore Ts'o
parent f32aaf2d2b
commit 8f888ef846
3 changed files with 33 additions and 7 deletions
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30
include/linux/jbd2.h
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@ -147,12 +147,24 @@ typedef struct journal_header_s
#define JBD2_CRC32_CHKSUM 1
#define JBD2_MD5_CHKSUM 2
#define JBD2_SHA1_CHKSUM 3
#define JBD2_CRC32C_CHKSUM 4
#define JBD2_CRC32_CHKSUM_SIZE 4
#define JBD2_CHECKSUM_BYTES (32 / sizeof(u32))
/*
* Commit block header for storing transactional checksums:
*
* NOTE: If FEATURE_COMPAT_CHECKSUM (checksum v1) is set, the h_chksum*
* fields are used to store a checksum of the descriptor and data blocks.
*
* If FEATURE_INCOMPAT_CSUM_V2 (checksum v2) is set, then the h_chksum
* field is used to store crc32c(uuid+commit_block). Each journal metadata
* block gets its own checksum, and data block checksums are stored in
* journal_block_tag (in the descriptor). The other h_chksum* fields are
* not used.
*
* Checksum v1 and v2 are mutually exclusive features.
*/
struct commit_header {
__be32 h_magic;
@ -175,13 +187,19 @@ struct commit_header {
typedef struct journal_block_tag_s
{
__be32 t_blocknr; /* The on-disk block number */
__be32 t_flags; /* See below */
__be16 t_checksum; /* truncated crc32c(uuid+seq+block) */
__be16 t_flags; /* See below */
__be32 t_blocknr_high; /* most-significant high 32bits. */
} journal_block_tag_t;
#define JBD2_TAG_SIZE32 (offsetof(journal_block_tag_t, t_blocknr_high))
#define JBD2_TAG_SIZE64 (sizeof(journal_block_tag_t))
/* Tail of descriptor block, for checksumming */
struct jbd2_journal_block_tail {
__be32 t_checksum; /* crc32c(uuid+descr_block) */
};
/*
* The revoke descriptor: used on disk to describe a series of blocks to
* be revoked from the log
@ -192,6 +210,10 @@ typedef struct jbd2_journal_revoke_header_s
__be32 r_count; /* Count of bytes used in the block */
} jbd2_journal_revoke_header_t;
/* Tail of revoke block, for checksumming */
struct jbd2_journal_revoke_tail {
__be32 r_checksum; /* crc32c(uuid+revoke_block) */
};
/* Definitions for the journal tag flags word: */
#define JBD2_FLAG_ESCAPE 1 /* on-disk block is escaped */
@ -241,7 +263,10 @@ typedef struct journal_superblock_s
__be32 s_max_trans_data; /* Limit of data blocks per trans. */
/* 0x0050 */
__u32 s_padding[44];
__u8 s_checksum_type; /* checksum type */
__u8 s_padding2[3];
__u32 s_padding[42];
__be32 s_checksum; /* crc32c(superblock) */
/* 0x0100 */
__u8 s_users[16*48]; /* ids of all fs'es sharing the log */
@ -263,6 +288,7 @@ typedef struct journal_superblock_s
#define JBD2_FEATURE_INCOMPAT_REVOKE 0x00000001
#define JBD2_FEATURE_INCOMPAT_64BIT 0x00000002
#define JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT 0x00000004
#define JBD2_FEATURE_INCOMPAT_CSUM_V2 0x00000008
/* Features known to this kernel version: */
#define JBD2_KNOWN_COMPAT_FEATURES JBD2_FEATURE_COMPAT_CHECKSUM