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 13typedef unsigned int tid_t; /* Unique transaction ID */ 14typedef struct transaction_s transaction_t; /* Compound transaction type */ 15 16 17struct buffer_head; 18 19struct 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