:header-rows: 1
* - Superblock
- - descriptor\_block (data\_blocks or revocation\_block) [more data or
- revocations] commmit\_block
+ - descriptor_block (data_blocks or revocation_block) [more data or
+ revocations] commmit_block
- [more transactions...]
* -
- One transaction
* - 1024 bytes of padding
- ext4 Superblock
- Journal Superblock
- - descriptor\_block (data\_blocks or revocation\_block) [more data or
- revocations] commmit\_block
+ - descriptor_block (data_blocks or revocation_block) [more data or
+ revocations] commmit_block
- [more transactions...]
* -
-
- Name
- Description
* - 0x0
- - \_\_be32
- - h\_magic
+ - __be32
+ - h_magic
- jbd2 magic number, 0xC03B3998.
* - 0x4
- - \_\_be32
- - h\_blocktype
+ - __be32
+ - h_blocktype
- Description of what this block contains. See the jbd2_blocktype_ table
below.
* - 0x8
- - \_\_be32
- - h\_sequence
+ - __be32
+ - h_sequence
- The transaction ID that goes with this block.
.. _jbd2_blocktype:
-
- Static information describing the journal.
* - 0x0
- - journal\_header\_t (12 bytes)
- - s\_header
+ - journal_header_t (12 bytes)
+ - s_header
- Common header identifying this as a superblock.
* - 0xC
- - \_\_be32
- - s\_blocksize
+ - __be32
+ - s_blocksize
- Journal device block size.
* - 0x10
- - \_\_be32
- - s\_maxlen
+ - __be32
+ - s_maxlen
- Total number of blocks in this journal.
* - 0x14
- - \_\_be32
- - s\_first
+ - __be32
+ - s_first
- First block of log information.
* -
-
-
- Dynamic information describing the current state of the log.
* - 0x18
- - \_\_be32
- - s\_sequence
+ - __be32
+ - s_sequence
- First commit ID expected in log.
* - 0x1C
- - \_\_be32
- - s\_start
+ - __be32
+ - s_start
- Block number of the start of log. Contrary to the comments, this field
being zero does not imply that the journal is clean!
* - 0x20
- - \_\_be32
- - s\_errno
- - Error value, as set by jbd2\_journal\_abort().
+ - __be32
+ - s_errno
+ - Error value, as set by jbd2_journal_abort().
* -
-
-
- The remaining fields are only valid in a v2 superblock.
* - 0x24
- - \_\_be32
- - s\_feature\_compat;
+ - __be32
+ - s_feature_compat;
- Compatible feature set. See the table jbd2_compat_ below.
* - 0x28
- - \_\_be32
- - s\_feature\_incompat
+ - __be32
+ - s_feature_incompat
- Incompatible feature set. See the table jbd2_incompat_ below.
* - 0x2C
- - \_\_be32
- - s\_feature\_ro\_compat
+ - __be32
+ - s_feature_ro_compat
- Read-only compatible feature set. There aren't any of these currently.
* - 0x30
- - \_\_u8
- - s\_uuid[16]
+ - __u8
+ - s_uuid[16]
- 128-bit uuid for journal. This is compared against the copy in the ext4
super block at mount time.
* - 0x40
- - \_\_be32
- - s\_nr\_users
+ - __be32
+ - s_nr_users
- Number of file systems sharing this journal.
* - 0x44
- - \_\_be32
- - s\_dynsuper
+ - __be32
+ - s_dynsuper
- Location of dynamic super block copy. (Not used?)
* - 0x48
- - \_\_be32
- - s\_max\_transaction
+ - __be32
+ - s_max_transaction
- Limit of journal blocks per transaction. (Not used?)
* - 0x4C
- - \_\_be32
- - s\_max\_trans\_data
+ - __be32
+ - s_max_trans_data
- Limit of data blocks per transaction. (Not used?)
* - 0x50
- - \_\_u8
- - s\_checksum\_type
+ - __u8
+ - s_checksum_type
- Checksum algorithm used for the journal. See jbd2_checksum_type_ for
more info.
* - 0x51
- - \_\_u8[3]
- - s\_padding2
+ - __u8[3]
+ - s_padding2
-
* - 0x54
- - \_\_be32
- - s\_num\_fc\_blocks
+ - __be32
+ - s_num_fc_blocks
- Number of fast commit blocks in the journal.
* - 0x58
- - \_\_u32
- - s\_padding[42]
+ - __u32
+ - s_padding[42]
-
* - 0xFC
- - \_\_be32
- - s\_checksum
+ - __be32
+ - s_checksum
- Checksum of the entire superblock, with this field set to zero.
* - 0x100
- - \_\_u8
- - s\_users[16\*48]
+ - __u8
+ - s_users[16*48]
- ids of all file systems sharing the log. e2fsprogs/Linux don't allow
shared external journals, but I imagine Lustre (or ocfs2?), which use
the jbd2 code, might.
- Description
* - 0x1
- Journal maintains checksums on the data blocks.
- (JBD2\_FEATURE\_COMPAT\_CHECKSUM)
+ (JBD2_FEATURE_COMPAT_CHECKSUM)
.. _jbd2_incompat:
* - Value
- Description
* - 0x1
- - Journal has block revocation records. (JBD2\_FEATURE\_INCOMPAT\_REVOKE)
+ - Journal has block revocation records. (JBD2_FEATURE_INCOMPAT_REVOKE)
* - 0x2
- Journal can deal with 64-bit block numbers.
- (JBD2\_FEATURE\_INCOMPAT\_64BIT)
+ (JBD2_FEATURE_INCOMPAT_64BIT)
* - 0x4
- - Journal commits asynchronously. (JBD2\_FEATURE\_INCOMPAT\_ASYNC\_COMMIT)
+ - Journal commits asynchronously. (JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)
* - 0x8
- This journal uses v2 of the checksum on-disk format. Each journal
metadata block gets its own checksum, and the block tags in the
descriptor table contain checksums for each of the data blocks in the
- journal. (JBD2\_FEATURE\_INCOMPAT\_CSUM\_V2)
+ journal. (JBD2_FEATURE_INCOMPAT_CSUM_V2)
* - 0x10
- This journal uses v3 of the checksum on-disk format. This is the same as
v2, but the journal block tag size is fixed regardless of the size of
- block numbers. (JBD2\_FEATURE\_INCOMPAT\_CSUM\_V3)
+ block numbers. (JBD2_FEATURE_INCOMPAT_CSUM_V3)
* - 0x20
- - Journal has fast commit blocks. (JBD2\_FEATURE\_INCOMPAT\_FAST\_COMMIT)
+ - Journal has fast commit blocks. (JBD2_FEATURE_INCOMPAT_FAST_COMMIT)
.. _jbd2_checksum_type:
- Name
- Descriptor
* - 0x0
- - journal\_header\_t
+ - journal_header_t
- (open coded)
- Common block header.
* - 0xC
- - struct journal\_block\_tag\_s
+ - struct journal_block_tag_s
- open coded array[]
- Enough tags either to fill up the block or to describe all the data
blocks that follow this descriptor block.
Journal block tags have any of the following formats, depending on which
journal feature and block tag flags are set.
-If JBD2\_FEATURE\_INCOMPAT\_CSUM\_V3 is set, the journal block tag is
+If JBD2_FEATURE_INCOMPAT_CSUM_V3 is set, the journal block tag is
defined as ``struct journal_block_tag3_s``, which looks like the
following. The size is 16 or 32 bytes.
- Name
- Descriptor
* - 0x0
- - \_\_be32
- - t\_blocknr
+ - __be32
+ - t_blocknr
- Lower 32-bits of the location of where the corresponding data block
should end up on disk.
* - 0x4
- - \_\_be32
- - t\_flags
+ - __be32
+ - t_flags
- Flags that go with the descriptor. See the table jbd2_tag_flags_ for
more info.
* - 0x8
- - \_\_be32
- - t\_blocknr\_high
+ - __be32
+ - t_blocknr_high
- Upper 32-bits of the location of where the corresponding data block
- should end up on disk. This is zero if JBD2\_FEATURE\_INCOMPAT\_64BIT is
+ should end up on disk. This is zero if JBD2_FEATURE_INCOMPAT_64BIT is
not enabled.
* - 0xC
- - \_\_be32
- - t\_checksum
+ - __be32
+ - t_checksum
- Checksum of the journal UUID, the sequence number, and the data block.
* -
-
* - 0x8
- This is the last tag in this descriptor block.
-If JBD2\_FEATURE\_INCOMPAT\_CSUM\_V3 is NOT set, the journal block tag
+If JBD2_FEATURE_INCOMPAT_CSUM_V3 is NOT set, the journal block tag
is defined as ``struct journal_block_tag_s``, which looks like the
following. The size is 8, 12, 24, or 28 bytes:
- Name
- Descriptor
* - 0x0
- - \_\_be32
- - t\_blocknr
+ - __be32
+ - t_blocknr
- Lower 32-bits of the location of where the corresponding data block
should end up on disk.
* - 0x4
- - \_\_be16
- - t\_checksum
+ - __be16
+ - t_checksum
- Checksum of the journal UUID, the sequence number, and the data block.
Note that only the lower 16 bits are stored.
* - 0x6
- - \_\_be16
- - t\_flags
+ - __be16
+ - t_flags
- Flags that go with the descriptor. See the table jbd2_tag_flags_ for
more info.
* -
- This next field is only present if the super block indicates support for
64-bit block numbers.
* - 0x8
- - \_\_be32
- - t\_blocknr\_high
+ - __be32
+ - t_blocknr_high
- Upper 32-bits of the location of where the corresponding data block
should end up on disk.
* -
``j_uuid`` field in ``struct journal_s``, but only tune2fs touches that
field.
-If JBD2\_FEATURE\_INCOMPAT\_CSUM\_V2 or
-JBD2\_FEATURE\_INCOMPAT\_CSUM\_V3 are set, the end of the block is a
+If JBD2_FEATURE_INCOMPAT_CSUM_V2 or
+JBD2_FEATURE_INCOMPAT_CSUM_V3 are set, the end of the block is a
``struct jbd2_journal_block_tail``, which looks like this:
.. list-table::
- Name
- Descriptor
* - 0x0
- - \_\_be32
- - t\_checksum
+ - __be32
+ - t_checksum
- Checksum of the journal UUID + the descriptor block, with this field set
to zero.
- Name
- Description
* - 0x0
- - journal\_header\_t
- - r\_header
+ - journal_header_t
+ - r_header
- Common block header.
* - 0xC
- - \_\_be32
- - r\_count
+ - __be32
+ - r_count
- Number of bytes used in this block.
* - 0x10
- - \_\_be32 or \_\_be64
+ - __be32 or __be64
- blocks[0]
- Blocks to revoke.
-After r\_count is a linear array of block numbers that are effectively
+After r_count is a linear array of block numbers that are effectively
revoked by this transaction. The size of each block number is 8 bytes if
the superblock advertises 64-bit block number support, or 4 bytes
otherwise.
-If JBD2\_FEATURE\_INCOMPAT\_CSUM\_V2 or
-JBD2\_FEATURE\_INCOMPAT\_CSUM\_V3 are set, the end of the revocation
+If JBD2_FEATURE_INCOMPAT_CSUM_V2 or
+JBD2_FEATURE_INCOMPAT_CSUM_V3 are set, the end of the revocation
block is a ``struct jbd2_journal_revoke_tail``, which has this format:
.. list-table::
- Name
- Description
* - 0x0
- - \_\_be32
- - r\_checksum
+ - __be32
+ - r_checksum
- Checksum of the journal UUID + revocation block
Commit Block
- Name
- Descriptor
* - 0x0
- - journal\_header\_s
+ - journal_header_s
- (open coded)
- Common block header.
* - 0xC
- unsigned char
- - h\_chksum\_type
+ - h_chksum_type
- The type of checksum to use to verify the integrity of the data blocks
in the transaction. See jbd2_checksum_type_ for more info.
* - 0xD
- unsigned char
- - h\_chksum\_size
+ - h_chksum_size
- The number of bytes used by the checksum. Most likely 4.
* - 0xE
- unsigned char
- - h\_padding[2]
+ - h_padding[2]
-
* - 0x10
- - \_\_be32
- - h\_chksum[JBD2\_CHECKSUM\_BYTES]
+ - __be32
+ - h_chksum[JBD2_CHECKSUM_BYTES]
- 32 bytes of space to store checksums. If
- JBD2\_FEATURE\_INCOMPAT\_CSUM\_V2 or JBD2\_FEATURE\_INCOMPAT\_CSUM\_V3
+ JBD2_FEATURE_INCOMPAT_CSUM_V2 or JBD2_FEATURE_INCOMPAT_CSUM_V3
are set, the first ``__be32`` is the checksum of the journal UUID and
the entire commit block, with this field zeroed. If
- JBD2\_FEATURE\_COMPAT\_CHECKSUM is set, the first ``__be32`` is the
+ JBD2_FEATURE_COMPAT_CHECKSUM is set, the first ``__be32`` is the
crc32 of all the blocks already written to the transaction.
* - 0x30
- - \_\_be64
- - h\_commit\_sec
+ - __be64
+ - h_commit_sec
- The time that the transaction was committed, in seconds since the epoch.
* - 0x38
- - \_\_be32
- - h\_commit\_nsec
+ - __be32
+ - h_commit_nsec
- Nanoseconds component of the above timestamp.
Fast commits
projects / platform / kernel / linux-starfive.git / blobdiff