1 /*
2 * include/linux/journal-head.h
3 *
4 * buffer_head fields for JBD
5 *
6 * 27 May 2001 Andrew Morton
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 */
15
16
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
43 /*
44 * Copy of the buffer data frozen for writing to the log.
45 * [jbd_lock_bh_state()]
46 */
47 char *b_frozen_data;
48
49 /*
50 * Pointer to a saved copy of the buffer containing no uncommitted
51 * deallocation references, so that allocations can avoid overwriting
52 * uncommitted deletes. [jbd_lock_bh_state()]
53 */
54 char *b_committed_data;
55
56 /*
57 * Pointer to the compound transaction which owns this buffer's
58 * metadata: either the running transaction or the committing
59 * transaction (if there is one). Only applies to buffers on a
60 * transaction's data or metadata journaling list.
61 * [j_list_lock] [jbd_lock_bh_state()]
62 */
63 transaction_t *b_transaction;
64
65 /*
66 * Pointer to the running compound transaction which is currently
67 * modifying the buffer's metadata, if there was already a transaction
68 * committing it when the new transaction touched it.
69 * [t_list_lock] [jbd_lock_bh_state()]
70 */
71 transaction_t *b_next_transaction;
72
73 /*
74 * Doubly-linked list of buffers on a transaction's data, metadata or
75 * forget queue. [t_list_lock] [jbd_lock_bh_state()]
76 */
77 struct journal_head *b_tnext, *b_tprev;
78
79 /*
80 * Pointer to the compound transaction against which this buffer
81 * is checkpointed. Only dirty buffers can be checkpointed.
82 * [j_list_lock]
83 */
84 transaction_t *b_cp_transaction;
85
86 /*
87 * Doubly-linked list of buffers still remaining to be flushed
88 * before an old transaction can be checkpointed.
89 * [j_list_lock]
90 */
91 struct journal_head *b_cpnext, *b_cpprev;
92
93 /* Trigger type */
94 struct jbd2_buffer_trigger_type *b_triggers;
95
96 /* Trigger type for the committing transaction's frozen data */
97 struct jbd2_buffer_trigger_type *b_frozen_triggers;
98 };
99
100 #endif /* JOURNAL_HEAD_H_INCLUDED */
101
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