user namespace: add the framework
[linux-2.6.git] / include / linux / journal-head.h
1 /*
2  * include/linux/journal-head.h
3  *
4  * buffer_head fields for JBD
5  *
6  * 27 May 2001 Andrew Morton <akpm@digeo.com>
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 struct buffer_head;
16
17 struct journal_head {
18         /*
19          * Points back to our buffer_head. [jbd_lock_bh_journal_head()]
20          */
21         struct buffer_head *b_bh;
22
23         /*
24          * Reference count - see description in journal.c
25          * [jbd_lock_bh_journal_head()]
26          */
27         int b_jcount;
28
29         /*
30          * Journalling list for this buffer [jbd_lock_bh_state()]
31          */
32         unsigned b_jlist;
33
34         /*
35          * This flag signals the buffer has been modified by
36          * the currently running transaction
37          * [jbd_lock_bh_state()]
38          */
39         unsigned b_modified;
40
41         /*
42          * Copy of the buffer data frozen for writing to the log.
43          * [jbd_lock_bh_state()]
44          */
45         char *b_frozen_data;
46
47         /*
48          * Pointer to a saved copy of the buffer containing no uncommitted
49          * deallocation references, so that allocations can avoid overwriting
50          * uncommitted deletes. [jbd_lock_bh_state()]
51          */
52         char *b_committed_data;
53
54         /*
55          * Pointer to the compound transaction which owns this buffer's
56          * metadata: either the running transaction or the committing
57          * transaction (if there is one).  Only applies to buffers on a
58          * transaction's data or metadata journaling list.
59          * [j_list_lock] [jbd_lock_bh_state()]
60          */
61         transaction_t *b_transaction;
62
63         /*
64          * Pointer to the running compound transaction which is currently
65          * modifying the buffer's metadata, if there was already a transaction
66          * committing it when the new transaction touched it.
67          * [t_list_lock] [jbd_lock_bh_state()]
68          */
69         transaction_t *b_next_transaction;
70
71         /*
72          * Doubly-linked list of buffers on a transaction's data, metadata or
73          * forget queue. [t_list_lock] [jbd_lock_bh_state()]
74          */
75         struct journal_head *b_tnext, *b_tprev;
76
77         /*
78          * Pointer to the compound transaction against which this buffer
79          * is checkpointed.  Only dirty buffers can be checkpointed.
80          * [j_list_lock]
81          */
82         transaction_t *b_cp_transaction;
83
84         /*
85          * Doubly-linked list of buffers still remaining to be flushed
86          * before an old transaction can be checkpointed.
87          * [j_list_lock]
88          */
89         struct journal_head *b_cpnext, *b_cpprev;
90 };
91
92 #endif          /* JOURNAL_HEAD_H_INCLUDED */