SYNOPSIS
struct journal_s {
unsigned long j_flags;
int j_errno;
struct buffer_head * j_sb_buffer;
journal_superblock_t * j_superblock;
int j_format_version;
spinlock_t j_state_lock;
int j_barrier_count;
transaction_t * j_running_transaction;
transaction_t * j_committing_transaction;
transaction_t * j_checkpoint_transactions;
wait_queue_head_t j_wait_transaction_locked;
wait_queue_head_t j_wait_logspace;
wait_queue_head_t j_wait_done_commit;
wait_queue_head_t j_wait_checkpoint;
wait_queue_head_t j_wait_commit;
wait_queue_head_t j_wait_updates;
struct mutex j_checkpoint_mutex;
unsigned int j_head;
unsigned int j_tail;
unsigned int j_free;
unsigned int j_first;
unsigned int j_last;
struct block_device * j_dev;
int j_blocksize;
unsigned int j_blk_offset;
struct block_device * j_fs_dev;
unsigned int j_maxlen;
spinlock_t j_list_lock;
struct inode * j_inode;
tid_t j_tail_sequence;
tid_t j_transaction_sequence;
tid_t j_commit_sequence;
tid_t j_commit_request;
tid_t j_commit_waited;
__u8 j_uuid[16];
struct task_struct * j_task;
int j_max_transaction_buffers;
unsigned long j_commit_interval;
struct timer_list j_commit_timer;
spinlock_t j_revoke_lock;
struct jbd_revoke_table_s * j_revoke;
struct jbd_revoke_table_s * j_revoke_table[2];
struct buffer_head ** j_wbuf;
int j_wbufsize;
pid_t j_last_sync_writer;
u64 j_average_commit_time;
void * j_private;
};
MEMBERS
j_flags
- General journaling state flags
j_errno
- Is there an outstanding uncleared error on the journal (from a prior abort)?
j_sb_buffer
- First part of superblock buffer
j_superblock
- Second part of superblock buffer
j_format_version
- Version of the superblock format
j_state_lock
- Protect the various scalars in the journal
j_barrier_count
- Number of processes waiting to create a barrier lock
j_running_transaction
- The current running transaction..
j_committing_transaction
- the transaction we are pushing to disk
j_checkpoint_transactions
- a linked circular list of all transactions waiting for checkpointing
j_wait_transaction_locked
- Wait queue for waiting for a locked transaction to start committing, or for a barrier lock to be released
j_wait_logspace
- Wait queue for waiting for checkpointing to complete
j_wait_done_commit
- Wait queue for waiting for commit to complete
j_wait_checkpoint
- Wait queue to trigger checkpointing
j_wait_commit
- Wait queue to trigger commit
j_wait_updates
- Wait queue to wait for updates to complete
j_checkpoint_mutex
- Mutex for locking against concurrent checkpoints
j_head
- Journal head - identifies the first unused block in the journal
j_tail
- Journal tail - identifies the oldest still-used block in the journal.
j_free
- Journal free - how many free blocks are there in the journal?
j_first
- The block number of the first usable block
j_last
- The block number one beyond the last usable block
j_dev
- Device where we store the journal
j_blocksize
- blocksize for the location where we store the journal.
j_blk_offset
- starting block offset for into the device where we store the journal
j_fs_dev
- Device which holds the client fs. For internal journal this will be equal to j_dev
j_maxlen
- Total maximum capacity of the journal region on disk.
j_list_lock
- Protects the buffer lists and internal buffer state.
j_inode
- Optional inode where we store the journal. If present, all journal block numbers are mapped into this inode via bmap.
j_tail_sequence
- Sequence number of the oldest transaction in the log
j_transaction_sequence
- Sequence number of the next transaction to grant
j_commit_sequence
- Sequence number of the most recently committed transaction
j_commit_request
- Sequence number of the most recent transaction wanting commit
j_commit_waited
- Sequence number of the most recent transaction someone is waiting for to commit.
j_uuid[16]
- Uuid of client object.
j_task
- Pointer to the current commit thread for this journal
j_max_transaction_buffers
- Maximum number of metadata buffers to allow in a single compound commit transaction
j_commit_interval
- What is the maximum transaction lifetime before we begin a commit?
j_commit_timer
- The timer used to wakeup the commit thread
j_revoke_lock
- Protect the revoke table
j_revoke
- The revoke table - maintains the list of revoked blocks in the current transaction.
j_revoke_table[2]
- alternate revoke tables for j_revoke
j_wbuf
- array of buffer_heads for journal_commit_transaction
j_wbufsize
- maximum number of buffer_heads allowed in j_wbuf, the number that will fit in j_blocksize
j_last_sync_writer
- most recent pid which did a synchronous write
j_average_commit_time
- the average amount of time in nanoseconds it takes to commit a transaction to the disk.
j_private
- An opaque pointer to fs-private information.
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