Commit 8f888ef8 authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Theodore Ts'o
Browse files

jbd2: change disk layout for metadata checksumming 



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

Signed-off-by: default avatarDarrick J. Wong <djwong@us.ibm.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent f32aaf2d

fs/jbd2/commit.c

+2 −2
Original line number Diff line number Diff line
@@ -627,7 +627,7 @@ void jbd2_journal_commit_transaction(journal_t *journal) 


		tag = (journal_block_tag_t *) tagp;

		write_tag_block(tag_bytes, tag, jh2bh(jh)->b_blocknr);

		tag->t_flags = cpu_to_be32(tag_flag);

		tag->t_flags = cpu_to_be16(tag_flag);

		tagp += tag_bytes;

		space_left -= tag_bytes;
@@ -651,7 +651,7 @@ void jbd2_journal_commit_transaction(journal_t *journal) 
                           submitting the IOs.  "tag" still points to

                           the last tag we set up. */



			tag->t_flags |= cpu_to_be32(JBD2_FLAG_LAST_TAG);

			tag->t_flags |= cpu_to_be16(JBD2_FLAG_LAST_TAG);



start_journal_io:

			for (i = 0; i < bufs; i++) {

fs/jbd2/recovery.c

+3 −3
Original line number Diff line number Diff line
@@ -193,10 +193,10 @@ static int count_tags(journal_t *journal, struct buffer_head *bh) 


		nr++;

		tagp += tag_bytes;

		if (!(tag->t_flags & cpu_to_be32(JBD2_FLAG_SAME_UUID)))

		if (!(tag->t_flags & cpu_to_be16(JBD2_FLAG_SAME_UUID)))

			tagp += 16;



		if (tag->t_flags & cpu_to_be32(JBD2_FLAG_LAST_TAG))

		if (tag->t_flags & cpu_to_be16(JBD2_FLAG_LAST_TAG))

			break;

	}
@@ -485,7 +485,7 @@ static int do_one_pass(journal_t *journal, 
				unsigned long io_block;



				tag = (journal_block_tag_t *) tagp;

				flags = be32_to_cpu(tag->t_flags);

				flags = be16_to_cpu(tag->t_flags);



				io_block = next_log_block++;

				wrap(journal, next_log_block);

include/linux/jbd2.h

+28 −2
Original line number Diff line number Diff line
@@ -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