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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 | ||
46417064 TG |
14 | #include <linux/spinlock.h> |
15 | ||
1da177e4 LT |
16 | typedef unsigned int tid_t; /* Unique transaction ID */ |
17 | typedef struct transaction_s transaction_t; /* Compound transaction type */ | |
e06c8227 JB |
18 | |
19 | ||
1da177e4 LT |
20 | struct buffer_head; |
21 | ||
22 | struct journal_head { | |
23 | /* | |
24 | * Points back to our buffer_head. [jbd_lock_bh_journal_head()] | |
25 | */ | |
26 | struct buffer_head *b_bh; | |
27 | ||
46417064 TG |
28 | /* |
29 | * Protect the buffer head state | |
30 | */ | |
31 | spinlock_t b_state_lock; | |
32 | ||
1da177e4 LT |
33 | /* |
34 | * Reference count - see description in journal.c | |
35 | * [jbd_lock_bh_journal_head()] | |
36 | */ | |
37 | int b_jcount; | |
38 | ||
39 | /* | |
46417064 | 40 | * Journalling list for this buffer [b_state_lock] |
e2555fde JK |
41 | * NOTE: We *cannot* combine this with b_modified into a bitfield |
42 | * as gcc would then (which the C standard allows but which is | |
43 | * very unuseful) make 64-bit accesses to the bitfield and clobber | |
44 | * b_jcount if its update races with bitfield modification. | |
1da177e4 | 45 | */ |
e2555fde | 46 | unsigned b_jlist; |
1da177e4 LT |
47 | |
48 | /* | |
49 | * This flag signals the buffer has been modified by | |
50 | * the currently running transaction | |
46417064 | 51 | * [b_state_lock] |
1da177e4 | 52 | */ |
e2555fde | 53 | unsigned b_modified; |
c2cc7028 | 54 | |
1da177e4 LT |
55 | /* |
56 | * Copy of the buffer data frozen for writing to the log. | |
46417064 | 57 | * [b_state_lock] |
1da177e4 LT |
58 | */ |
59 | char *b_frozen_data; | |
60 | ||
61 | /* | |
62 | * Pointer to a saved copy of the buffer containing no uncommitted | |
63 | * deallocation references, so that allocations can avoid overwriting | |
46417064 | 64 | * uncommitted deletes. [b_state_lock] |
1da177e4 LT |
65 | */ |
66 | char *b_committed_data; | |
67 | ||
68 | /* | |
69 | * Pointer to the compound transaction which owns this buffer's | |
70 | * metadata: either the running transaction or the committing | |
71 | * transaction (if there is one). Only applies to buffers on a | |
72 | * transaction's data or metadata journaling list. | |
46417064 | 73 | * [j_list_lock] [b_state_lock] |
932bb305 JK |
74 | * Either of these locks is enough for reading, both are needed for |
75 | * changes. | |
1da177e4 LT |
76 | */ |
77 | transaction_t *b_transaction; | |
78 | ||
79 | /* | |
80 | * Pointer to the running compound transaction which is currently | |
81 | * modifying the buffer's metadata, if there was already a transaction | |
82 | * committing it when the new transaction touched it. | |
46417064 | 83 | * [t_list_lock] [b_state_lock] |
1da177e4 LT |
84 | */ |
85 | transaction_t *b_next_transaction; | |
86 | ||
87 | /* | |
88 | * Doubly-linked list of buffers on a transaction's data, metadata or | |
46417064 | 89 | * forget queue. [t_list_lock] [b_state_lock] |
1da177e4 LT |
90 | */ |
91 | struct journal_head *b_tnext, *b_tprev; | |
92 | ||
93 | /* | |
94 | * Pointer to the compound transaction against which this buffer | |
95 | * is checkpointed. Only dirty buffers can be checkpointed. | |
96 | * [j_list_lock] | |
97 | */ | |
98 | transaction_t *b_cp_transaction; | |
99 | ||
100 | /* | |
101 | * Doubly-linked list of buffers still remaining to be flushed | |
102 | * before an old transaction can be checkpointed. | |
103 | * [j_list_lock] | |
104 | */ | |
105 | struct journal_head *b_cpnext, *b_cpprev; | |
e06c8227 JB |
106 | |
107 | /* Trigger type */ | |
108 | struct jbd2_buffer_trigger_type *b_triggers; | |
109 | ||
110 | /* Trigger type for the committing transaction's frozen data */ | |
111 | struct jbd2_buffer_trigger_type *b_frozen_triggers; | |
1da177e4 LT |
112 | }; |
113 | ||
114 | #endif /* JOURNAL_HEAD_H_INCLUDED */ |