Merge remote-tracking branch 'spi/topic/ep93xx' into spi-next
[pandora-kernel.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
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          * NOTE: We *cannot* combine this with b_modified into a bitfield
34          * as gcc would then (which the C standard allows but which is
35          * very unuseful) make 64-bit accesses to the bitfield and clobber
36          * b_jcount if its update races with bitfield modification.
37          */
38         unsigned b_jlist;
39
40         /*
41          * This flag signals the buffer has been modified by
42          * the currently running transaction
43          * [jbd_lock_bh_state()]
44          */
45         unsigned b_modified;
46
47         /*
48          * Copy of the buffer data frozen for writing to the log.
49          * [jbd_lock_bh_state()]
50          */
51         char *b_frozen_data;
52
53         /*
54          * Pointer to a saved copy of the buffer containing no uncommitted
55          * deallocation references, so that allocations can avoid overwriting
56          * uncommitted deletes. [jbd_lock_bh_state()]
57          */
58         char *b_committed_data;
59
60         /*
61          * Pointer to the compound transaction which owns this buffer's
62          * metadata: either the running transaction or the committing
63          * transaction (if there is one).  Only applies to buffers on a
64          * transaction's data or metadata journaling list.
65          * [j_list_lock] [jbd_lock_bh_state()]
66          * Either of these locks is enough for reading, both are needed for
67          * changes.
68          */
69         transaction_t *b_transaction;
70
71         /*
72          * Pointer to the running compound transaction which is currently
73          * modifying the buffer's metadata, if there was already a transaction
74          * committing it when the new transaction touched it.
75          * [t_list_lock] [jbd_lock_bh_state()]
76          */
77         transaction_t *b_next_transaction;
78
79         /*
80          * Doubly-linked list of buffers on a transaction's data, metadata or
81          * forget queue. [t_list_lock] [jbd_lock_bh_state()]
82          */
83         struct journal_head *b_tnext, *b_tprev;
84
85         /*
86          * Pointer to the compound transaction against which this buffer
87          * is checkpointed.  Only dirty buffers can be checkpointed.
88          * [j_list_lock]
89          */
90         transaction_t *b_cp_transaction;
91
92         /*
93          * Doubly-linked list of buffers still remaining to be flushed
94          * before an old transaction can be checkpointed.
95          * [j_list_lock]
96          */
97         struct journal_head *b_cpnext, *b_cpprev;
98
99         /* Trigger type */
100         struct jbd2_buffer_trigger_type *b_triggers;
101
102         /* Trigger type for the committing transaction's frozen data */
103         struct jbd2_buffer_trigger_type *b_frozen_triggers;
104 };
105
106 #endif          /* JOURNAL_HEAD_H_INCLUDED */