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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
1da177e4 LT |
2 | /* |
3 | * include/linux/journal-head.h | |
4 | * | |
5 | * buffer_head fields for JBD | |
6 | * | |
e1f8e874 | 7 | * 27 May 2001 Andrew Morton |
1da177e4 LT |
8 | * Created - pulled out of fs.h |
9 | */ | |
10 | ||
11 | #ifndef JOURNAL_HEAD_H_INCLUDED | |
12 | #define JOURNAL_HEAD_H_INCLUDED | |
13 | ||
14 | typedef unsigned int tid_t; /* Unique transaction ID */ | |
15 | typedef struct transaction_s transaction_t; /* Compound transaction type */ | |
e06c8227 JB |
16 | |
17 | ||
1da177e4 LT |
18 | struct buffer_head; |
19 | ||
20 | struct journal_head { | |
21 | /* | |
22 | * Points back to our buffer_head. [jbd_lock_bh_journal_head()] | |
23 | */ | |
24 | struct buffer_head *b_bh; | |
25 | ||
26 | /* | |
27 | * Reference count - see description in journal.c | |
28 | * [jbd_lock_bh_journal_head()] | |
29 | */ | |
30 | int b_jcount; | |
31 | ||
32 | /* | |
33 | * Journalling list for this buffer [jbd_lock_bh_state()] | |
e2555fde JK |
34 | * NOTE: We *cannot* combine this with b_modified into a bitfield |
35 | * as gcc would then (which the C standard allows but which is | |
36 | * very unuseful) make 64-bit accesses to the bitfield and clobber | |
37 | * b_jcount if its update races with bitfield modification. | |
1da177e4 | 38 | */ |
e2555fde | 39 | unsigned b_jlist; |
1da177e4 LT |
40 | |
41 | /* | |
42 | * This flag signals the buffer has been modified by | |
43 | * the currently running transaction | |
44 | * [jbd_lock_bh_state()] | |
45 | */ | |
e2555fde | 46 | unsigned b_modified; |
c2cc7028 | 47 | |
1da177e4 LT |
48 | /* |
49 | * Copy of the buffer data frozen for writing to the log. | |
50 | * [jbd_lock_bh_state()] | |
51 | */ | |
52 | char *b_frozen_data; | |
53 | ||
54 | /* | |
55 | * Pointer to a saved copy of the buffer containing no uncommitted | |
56 | * deallocation references, so that allocations can avoid overwriting | |
57 | * uncommitted deletes. [jbd_lock_bh_state()] | |
58 | */ | |
59 | char *b_committed_data; | |
60 | ||
61 | /* | |
62 | * Pointer to the compound transaction which owns this buffer's | |
63 | * metadata: either the running transaction or the committing | |
64 | * transaction (if there is one). Only applies to buffers on a | |
65 | * transaction's data or metadata journaling list. | |
66 | * [j_list_lock] [jbd_lock_bh_state()] | |
932bb305 JK |
67 | * Either of these locks is enough for reading, both are needed for |
68 | * changes. | |
1da177e4 LT |
69 | */ |
70 | transaction_t *b_transaction; | |
71 | ||
72 | /* | |
73 | * Pointer to the running compound transaction which is currently | |
74 | * modifying the buffer's metadata, if there was already a transaction | |
75 | * committing it when the new transaction touched it. | |
76 | * [t_list_lock] [jbd_lock_bh_state()] | |
77 | */ | |
78 | transaction_t *b_next_transaction; | |
79 | ||
80 | /* | |
81 | * Doubly-linked list of buffers on a transaction's data, metadata or | |
82 | * forget queue. [t_list_lock] [jbd_lock_bh_state()] | |
83 | */ | |
84 | struct journal_head *b_tnext, *b_tprev; | |
85 | ||
86 | /* | |
87 | * Pointer to the compound transaction against which this buffer | |
88 | * is checkpointed. Only dirty buffers can be checkpointed. | |
89 | * [j_list_lock] | |
90 | */ | |
91 | transaction_t *b_cp_transaction; | |
92 | ||
93 | /* | |
94 | * Doubly-linked list of buffers still remaining to be flushed | |
95 | * before an old transaction can be checkpointed. | |
96 | * [j_list_lock] | |
97 | */ | |
98 | struct journal_head *b_cpnext, *b_cpprev; | |
e06c8227 JB |
99 | |
100 | /* Trigger type */ | |
101 | struct jbd2_buffer_trigger_type *b_triggers; | |
102 | ||
103 | /* Trigger type for the committing transaction's frozen data */ | |
104 | struct jbd2_buffer_trigger_type *b_frozen_triggers; | |
1da177e4 LT |
105 | }; |
106 | ||
107 | #endif /* JOURNAL_HEAD_H_INCLUDED */ |