text: /*
   * include/linux/journal-head.h
   *
   * buffer_head fields for JBD
   *
   * 27 May 2001 ANdrew Morton <andrewm@uow.edu.au>
   *	Created - pulled out of fs.h
   */
  
  #ifndef JOURNAL_HEAD_H_INCLUDED
  #define JOURNAL_HEAD_H_INCLUDED
  
  typedef unsigned int		tid_t;		/* Unique transaction ID */
  typedef struct transaction_s	transaction_t;	/* Compound transaction type */
  struct buffer_head;
  
  struct journal_head {
  #ifndef CONFIG_JBD_UNIFIED_BUFFERS
  	/* Points back to our buffer_head. */
  	struct buffer_head *b_bh;
  #endif
  
  	/* Reference count - see description in journal.c */
  	int b_jcount;
  
  	/* Journaling list for this buffer */
  	unsigned b_jlist;
  
  	/* Copy of the buffer data frozen for writing to the log. */
  	char * b_frozen_data;
  
  	/* Pointer to a saved copy of the buffer containing no
             uncommitted deallocation references, so that allocations can
             avoid overwriting uncommitted deletes. */
  	char * b_committed_data;
  
  	/* Pointer to the compound transaction which owns this buffer's
             metadata: either the running transaction or the committing
             transaction (if there is one).  Only applies to buffers on a
             transaction's data or metadata journaling list. */
  	/* Protected by journal_datalist_lock */
  	transaction_t * b_transaction;
  	
  	/* Pointer to the running compound transaction which is
             currently modifying the buffer's metadata, if there was
             already a transaction committing it when the new transaction
             touched it. */
  	transaction_t * b_next_transaction;
  	
  	/* Doubly-linked list of buffers on a transaction's data,
             metadata or forget queue. */
  	/* Protected by journal_datalist_lock */
  	struct journal_head *b_tnext, *b_tprev;
  
  	/*
  	 * Pointer to the compound transaction against which this buffer
  	 * is checkpointed.  Only dirty buffers can be checkpointed.
  	 */
  	/* Protected by journal_datalist_lock */
  	transaction_t * b_cp_transaction;
  	
  	/*
  	 * Doubly-linked list of buffers still remaining to be flushed
  	 * before an old transaction can be checkpointed.
  	 */
  	/* Protected by journal_datalist_lock */
  	struct journal_head *b_cpnext, *b_cpprev;
  };
  
  #endif		/* JOURNAL_HEAD_H_INCLUDED */
  