[mirror_ubuntu-bionic-kernel.git] / include / linux / journal-head.h

/*
 * include/linux/journal-head.h
 *
 * buffer_head fields for JBD
 *
 * 27 May 2001 Andrew Morton
 *	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 {
	/*
	 * Points back to our buffer_head. [jbd_lock_bh_journal_head()]
	 */
	struct buffer_head *b_bh;

	/*
	 * Reference count - see description in journal.c
	 * [jbd_lock_bh_journal_head()]
	 */
	int b_jcount;

	/*
	 * Journalling list for this buffer [jbd_lock_bh_state()]
	 */
	unsigned b_jlist;

	/*
	 * This flag signals the buffer has been modified by
	 * the currently running transaction
	 * [jbd_lock_bh_state()]
	 */
	unsigned b_modified;

	/*
	 * This feild tracks the last transaction id in which this buffer
	 * has been cowed
	 * [jbd_lock_bh_state()]
	 */
	tid_t b_cow_tid;

	/*
	 * Copy of the buffer data frozen for writing to the log.
	 * [jbd_lock_bh_state()]
	 */
	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. [jbd_lock_bh_state()]
	 */
	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.
	 * [j_list_lock] [jbd_lock_bh_state()]
	 * Either of these locks is enough for reading, both are needed for
	 * changes.
	 */
	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.
	 * [t_list_lock] [jbd_lock_bh_state()]
	 */
	transaction_t *b_next_transaction;

	/*
	 * Doubly-linked list of buffers on a transaction's data, metadata or
	 * forget queue. [t_list_lock] [jbd_lock_bh_state()]
	 */
	struct journal_head *b_tnext, *b_tprev;

	/*
	 * Pointer to the compound transaction against which this buffer
	 * is checkpointed.  Only dirty buffers can be checkpointed.
	 * [j_list_lock]
	 */
	transaction_t *b_cp_transaction;

	/*
	 * Doubly-linked list of buffers still remaining to be flushed
	 * before an old transaction can be checkpointed.
	 * [j_list_lock]
	 */
	struct journal_head *b_cpnext, *b_cpprev;

	/* Trigger type */
	struct jbd2_buffer_trigger_type *b_triggers;

	/* Trigger type for the committing transaction's frozen data */
	struct jbd2_buffer_trigger_type *b_frozen_triggers;
};

#endif		/* JOURNAL_HEAD_H_INCLUDED */
Commit	Line	Data
1da177e4 LT	1	/*
	2	* include/linux/journal-head.h
	3	*
	4	* buffer_head fields for JBD
	5	*
e1f8e874	6	* 27 May 2001 Andrew Morton
1da177e4 LT	7	* Created - pulled out of fs.h
	8	*/
	9
	10	#ifndef JOURNAL_HEAD_H_INCLUDED
	11	#define JOURNAL_HEAD_H_INCLUDED
	12
	13	typedef unsigned int tid_t; /* Unique transaction ID */
	14	typedef struct transaction_s transaction_t; /* Compound transaction type */
e06c8227 JB	15
e06c8227 JB	16
1da177e4 LT	17	struct buffer_head;
	18
	19	struct journal_head {
	20	/*
	21	* Points back to our buffer_head. [jbd_lock_bh_journal_head()]
	22	*/
	23	struct buffer_head *b_bh;
	24
	25	/*
	26	* Reference count - see description in journal.c
	27	* [jbd_lock_bh_journal_head()]
	28	*/
	29	int b_jcount;
	30
	31	/*
	32	* Journalling list for this buffer [jbd_lock_bh_state()]
	33	*/
	34	unsigned b_jlist;
	35
	36	/*
	37	* This flag signals the buffer has been modified by
	38	* the currently running transaction
	39	* [jbd_lock_bh_state()]
	40	*/
	41	unsigned b_modified;
	42
c2cc7028 AG	43	/*
	44	* This feild tracks the last transaction id in which this buffer
	45	* has been cowed
	46	* [jbd_lock_bh_state()]
	47	*/
5cf49d76	48	tid_t b_cow_tid;
c2cc7028	49
1da177e4 LT	50	/*
	51	* Copy of the buffer data frozen for writing to the log.
	52	* [jbd_lock_bh_state()]
	53	*/
	54	char *b_frozen_data;
	55
	56	/*
	57	* Pointer to a saved copy of the buffer containing no uncommitted
	58	* deallocation references, so that allocations can avoid overwriting
	59	* uncommitted deletes. [jbd_lock_bh_state()]
	60	*/
	61	char *b_committed_data;
	62
	63	/*
	64	* Pointer to the compound transaction which owns this buffer's
	65	* metadata: either the running transaction or the committing
	66	* transaction (if there is one). Only applies to buffers on a
	67	* transaction's data or metadata journaling list.
	68	* [j_list_lock] [jbd_lock_bh_state()]
932bb305 JK	69	* Either of these locks is enough for reading, both are needed for
932bb305 JK	70	* changes.
1da177e4 LT	71	*/
	72	transaction_t *b_transaction;
	73
	74	/*
	75	* Pointer to the running compound transaction which is currently
	76	* modifying the buffer's metadata, if there was already a transaction
	77	* committing it when the new transaction touched it.
	78	* [t_list_lock] [jbd_lock_bh_state()]
	79	*/
	80	transaction_t *b_next_transaction;
	81
	82	/*
	83	* Doubly-linked list of buffers on a transaction's data, metadata or
	84	* forget queue. [t_list_lock] [jbd_lock_bh_state()]
	85	*/
	86	struct journal_head b_tnext, b_tprev;
	87
	88	/*
	89	* Pointer to the compound transaction against which this buffer
	90	* is checkpointed. Only dirty buffers can be checkpointed.
	91	* [j_list_lock]
	92	*/
	93	transaction_t *b_cp_transaction;
	94
	95	/*
	96	* Doubly-linked list of buffers still remaining to be flushed
	97	* before an old transaction can be checkpointed.
	98	* [j_list_lock]
	99	*/
	100	struct journal_head b_cpnext, b_cpprev;
e06c8227 JB	101
	102	/* Trigger type */
	103	struct jbd2_buffer_trigger_type *b_triggers;
	104
	105	/* Trigger type for the committing transaction's frozen data */
	106	struct jbd2_buffer_trigger_type *b_frozen_triggers;
1da177e4 LT	107	};
	108
	109	#endif /* JOURNAL_HEAD_H_INCLUDED */