jbd.h

可以在不启动LINUX的情况下直接访问EXT2和EXT3格式的磁盘

	int			j_blocksize;
	unsigned long		j_blk_offset;

	/*
	 * Device which holds the client fs.  For internal journal this will be
	 * equal to j_dev.
	 */
	struct block_device	*j_fs_dev;

	/* Total maximum capacity of the journal region on disk. */
	unsigned int		j_maxlen;

	/*
	 * Protects the buffer lists and internal buffer state.
	 */
	spinlock_t		j_list_lock;

	/* Optional inode where we store the journal.  If present, all */
	/* journal block numbers are mapped into this inode via */
	/* bmap(). */
	struct inode		*j_inode;

	/*
	 * Sequence number of the oldest transaction in the log [j_state_lock]
	 */
	tid_t			j_tail_sequence;

	/*
	 * Sequence number of the next transaction to grant [j_state_lock]
	 */
	tid_t			j_transaction_sequence;

	/*
	 * Sequence number of the most recently committed transaction
	 * [j_state_lock].
	 */
	tid_t			j_commit_sequence;

	/*
	 * Sequence number of the most recent transaction wanting commit
	 * [j_state_lock]
	 */
	tid_t			j_commit_request;

	/*
	 * Journal uuid: identifies the object (filesystem, LVM volume etc)
	 * backed by this journal.  This will eventually be replaced by an array
	 * of uuids, allowing us to index multiple devices within a single
	 * journal and to perform atomic updates across them.
	 */
	__u8			j_uuid[16];

	/* Pointer to the current commit thread for this journal */
	struct task_struct	*j_task;

	/*
	 * Maximum number of metadata buffers to allow in a single compound
	 * commit transaction
	 */
	int			j_max_transaction_buffers;

	/*
	 * What is the maximum transaction lifetime before we begin a commit?
	 */
	unsigned long		j_commit_interval;

	/* The timer used to wakeup the commit thread: */
	struct timer_list	j_commit_timer;

	/*
	 * The revoke table: maintains the list of revoked blocks in the
	 * current transaction.  [j_revoke_lock]
	 */
	spinlock_t		j_revoke_lock;
	struct jbd_revoke_table_s *j_revoke;
	struct jbd_revoke_table_s *j_revoke_table[2];

	/*
	 * array of bhs for journal_commit_transaction
	 */
	struct buffer_head	**j_wbuf;
	int			j_wbufsize;

	pid_t			j_last_sync_writer;

	/*
	 * An opaque pointer to fs-private information.  ext3 puts its
	 * superblock pointer here
	 */
	void *j_private;
};

/*
 * Journal flag definitions
 */
#define JFS_UNMOUNT	0x001	/* Journal thread is being destroyed */
#define JFS_ABORT	0x002	/* Journaling has been aborted for errors. */
#define JFS_ACK_ERR	0x004	/* The errno in the sb has been acked */
#define JFS_FLUSHED	0x008	/* The journal superblock has been flushed */
#define JFS_LOADED	0x010	/* The journal superblock has been loaded */
#define JFS_BARRIER	0x020	/* Use IDE barriers */

/*
 * Function declarations for the journaling transaction and buffer
 * management
 */

/* Filing buffers */
extern void journal_unfile_buffer(journal_t *, struct journal_head *);
extern void __journal_unfile_buffer(struct journal_head *);
extern void __journal_refile_buffer(struct journal_head *);
extern void journal_refile_buffer(journal_t *, struct journal_head *);
extern void __journal_file_buffer(struct journal_head *, transaction_t *, int);
extern void __journal_free_buffer(struct journal_head *bh);
extern void journal_file_buffer(struct journal_head *, transaction_t *, int);
extern void __journal_clean_data_list(transaction_t *transaction);

/* Log buffer allocation */
extern struct journal_head * journal_get_descriptor_buffer(journal_t *);
int journal_next_log_block(journal_t *, unsigned long *);

/* Commit management */
extern void journal_commit_transaction(journal_t *);

/* Checkpoint list management */
int __journal_clean_checkpoint_list(journal_t *journal);
int __journal_remove_checkpoint(struct journal_head *);
void __journal_insert_checkpoint(struct journal_head *, transaction_t *);

/* Buffer IO */
extern int
journal_write_metadata_buffer(transaction_t	  *transaction,
			      struct journal_head  *jh_in,
			      struct journal_head **jh_out,
			      unsigned long	   blocknr);

/* Transaction locking */
extern void		__wait_on_journal (journal_t *);

/*
 * Journal locking.
 *
 * We need to lock the journal during transaction state changes so that nobody
 * ever tries to take a handle on the running transaction while we are in the
 * middle of moving it to the commit phase.  j_state_lock does this.
 *
 * Note that the locking is completely interrupt unsafe.  We never touch
 * journal structures from interrupts.
 */

static inline handle_t *journal_current_handle(void)
{
    return NULL;
	/* return current->journal_info; */
#pragma message("WARNINGS: journal_current_handle NOT implemented")
}

/* The journaling code user interface:
 *
 * Create and destroy handles
 * Register buffer modifications against the current transaction.
 */

extern handle_t *journal_start(journal_t *, int nblocks);
extern int	 journal_restart (handle_t *, int nblocks);
extern int	 journal_extend (handle_t *, int nblocks);
extern int	 journal_get_write_access(handle_t *, struct buffer_head *);
extern int	 journal_get_create_access (handle_t *, struct buffer_head *);
extern int	 journal_get_undo_access(handle_t *, struct buffer_head *);
extern int	 journal_dirty_data (handle_t *, struct buffer_head *);
extern int	 journal_dirty_metadata (handle_t *, struct buffer_head *);
extern void	 journal_release_buffer (handle_t *, struct buffer_head *);
extern int	 journal_forget (handle_t *, struct buffer_head *);
extern void	 journal_sync_buffer (struct buffer_head *);
extern void	 journal_invalidatepage(journal_t *,
				struct page *, unsigned long);
extern int	 journal_try_to_free_buffers(journal_t *, struct page *, gfp_t);
extern int	 journal_stop(handle_t *);
extern int	 journal_flush (journal_t *);
extern void	 journal_lock_updates (journal_t *);
extern void	 journal_unlock_updates (journal_t *);

extern journal_t * journal_init_dev(struct block_device *bdev,
				struct block_device *fs_dev,
				int start, int len, int bsize);
extern journal_t * journal_init_inode (struct inode *);
extern int	   journal_update_format (journal_t *);
extern int	   journal_check_used_features
		   (journal_t *, unsigned long, unsigned long, unsigned long);
extern int	   journal_check_available_features
		   (journal_t *, unsigned long, unsigned long, unsigned long);
extern int	   journal_set_features
		   (journal_t *, unsigned long, unsigned long, unsigned long);
extern int	   journal_create     (journal_t *);
extern int	   journal_load       (journal_t *journal);
extern void	   journal_destroy    (journal_t *);
extern int	   journal_recover    (journal_t *journal);
extern int	   journal_wipe       (journal_t *, int);
extern int	   journal_skip_recovery	(journal_t *);
extern void	   journal_update_superblock	(journal_t *, int);
       void	   journal_abort      (journal_t *, int);
extern int	   journal_errno      (journal_t *);
extern void	   journal_ack_err    (journal_t *);
extern int	   journal_clear_err  (journal_t *);
extern int	   journal_bmap(journal_t *, unsigned long, unsigned long *);
extern int	   journal_force_commit(journal_t *);

/* added by matt */
void journal_wipe_recovery(journal_t *journal);

/*
 * journal_head management
 */
struct journal_head *journal_add_journal_head(struct buffer_head *bh);
struct journal_head *journal_grab_journal_head(struct buffer_head *bh);
void journal_remove_journal_head(struct buffer_head *bh);
void journal_put_journal_head(struct journal_head *jh);

/*
 * handle management
 */
extern struct kmem_cache *jbd_handle_cache;

static inline handle_t *jbd_alloc_handle(gfp_t gfp_flags)
{
	return (handle_t *)kmem_cache_alloc(jbd_handle_cache, gfp_flags);
}

static inline void jbd_free_handle(handle_t *handle)
{
	kmem_cache_free(jbd_handle_cache, handle);
}

/* Primary revoke support */
#define JOURNAL_REVOKE_DEFAULT_HASH 256
extern int	   journal_init_revoke(journal_t *, int);
extern void	   journal_destroy_revoke_caches(void);
extern int	   journal_init_revoke_caches(void);

extern void	   journal_destroy_revoke(journal_t *);
extern int	   journal_revoke (handle_t *,
				unsigned long, struct buffer_head *);
extern int	   journal_cancel_revoke(handle_t *, struct journal_head *);
extern void	   journal_write_revoke_records(journal_t *, transaction_t *);

/* Recovery revoke support */
extern int	journal_set_revoke(journal_t *, unsigned long, tid_t);
extern int	journal_test_revoke(journal_t *, unsigned long, tid_t);
extern void	journal_clear_revoke(journal_t *);
extern void	journal_switch_revoke_table(journal_t *journal);

/*
 * The log thread user interface:
 *
 * Request space in the current transaction, and force transaction commit
 * transitions on demand.
 */

int __log_space_left(journal_t *); /* Called with journal locked */
int log_start_commit(journal_t *journal, tid_t tid);
int __log_start_commit(journal_t *journal, tid_t tid);
int journal_start_commit(journal_t *journal, tid_t *tid);
int journal_force_commit_nested(journal_t *journal);
int log_wait_commit(journal_t *journal, tid_t tid);
int log_do_checkpoint(journal_t *journal);

void __log_wait_for_space(journal_t *journal);
extern void	__journal_drop_transaction(journal_t *, transaction_t *);
extern int	cleanup_journal_tail(journal_t *);

/* Debugging code only: */

#define jbd_ENOSYS() \
do {								           \
	printk (KERN_ERR "JBD unimplemented function %s\n", __FUNCTION__); \
	current->state = TASK_UNINTERRUPTIBLE;			           \
	schedule();						           \
} while (1)

/*
 * is_journal_abort
 *
 * Simple test wrapper function to test the JFS_ABORT state flag.  This
 * bit, when set, indicates that we have had a fatal error somewhere,
 * either inside the journaling layer or indicated to us by the client
 * (eg. ext3), and that we and should not commit any further
 * transactions.
 */

static inline int is_journal_aborted(journal_t *journal)
{
	return journal->j_flags & JFS_ABORT;
}

static inline int is_handle_aborted(handle_t *handle)
{
	if (handle->h_aborted)
		return 1;
	return is_journal_aborted(handle->h_transaction->t_journal);
}

static inline void journal_abort_handle(handle_t *handle)
{
	handle->h_aborted = 1;
}

#endif /* __KERNEL__   */

/* Comparison functions for transaction IDs: perform comparisons using
 * modulo arithmetic so that they work over sequence number wraps. */

static inline int tid_gt(tid_t x, tid_t y)
{
	int difference = (x - y);
	return (difference > 0);
}

static inline int tid_geq(tid_t x, tid_t y)
{
	int difference = (x - y);
	return (difference >= 0);
}

extern int journal_blocks_per_page(struct inode *inode);

/*
 * Return the minimum number of blocks which must be free in the journal
 * before a new transaction may be started.  Must be called under j_state_lock.
 */
static inline int jbd_space_needed(journal_t *journal)
{
	int nblocks = journal->j_max_transaction_buffers;
	if (journal->j_committing_transaction)
		nblocks += journal->j_committing_transaction->
					t_outstanding_credits;
	return nblocks;
}

/*
 * Definitions which augment the buffer_head layer
 */

/* journaling buffer types */
#define BJ_None		0	/* Not journaled */
#define BJ_SyncData	1	/* Normal data: flush before commit */
#define BJ_Metadata	2	/* Normal journaled metadata */
#define BJ_Forget	3	/* Buffer superseded by this transaction */
#define BJ_IO		4	/* Buffer is for temporary IO use */
#define BJ_Shadow	5	/* Buffer contents being shadowed to the log */
#define BJ_LogCtl	6	/* Buffer contains log descriptors */
#define BJ_Reserved	7	/* Buffer is reserved for access by journal */
#define BJ_Locked	8	/* Locked for I/O during commit */
#define BJ_Types	9

extern int jbd_blocks_per_page(struct inode *inode);

#ifdef __KERNEL__

#define buffer_trace_init(bh)	do {} while (0)
#define print_buffer_fields(bh)	do {} while (0)
#define print_buffer_trace(bh)	do {} while (0)
#define BUFFER_TRACE(bh, info)	do {} while (0)
#define BUFFER_TRACE2(bh, bh2, info)	do {} while (0)
#define JBUFFER_TRACE(jh, info)	do {} while (0)

#endif	/* __KERNEL__ */

#endif	/* _LINUX_JBD_H */