1*4882a593Smuzhiyun /* SPDX-License-Identifier: GPL-2.0 */ 2*4882a593Smuzhiyun /* 3*4882a593Smuzhiyun * include/linux/journal-head.h 4*4882a593Smuzhiyun * 5*4882a593Smuzhiyun * buffer_head fields for JBD 6*4882a593Smuzhiyun * 7*4882a593Smuzhiyun * 27 May 2001 Andrew Morton 8*4882a593Smuzhiyun * Created - pulled out of fs.h 9*4882a593Smuzhiyun */ 10*4882a593Smuzhiyun 11*4882a593Smuzhiyun #ifndef JOURNAL_HEAD_H_INCLUDED 12*4882a593Smuzhiyun #define JOURNAL_HEAD_H_INCLUDED 13*4882a593Smuzhiyun 14*4882a593Smuzhiyun #include <linux/spinlock.h> 15*4882a593Smuzhiyun 16*4882a593Smuzhiyun typedef unsigned int tid_t; /* Unique transaction ID */ 17*4882a593Smuzhiyun typedef struct transaction_s transaction_t; /* Compound transaction type */ 18*4882a593Smuzhiyun 19*4882a593Smuzhiyun 20*4882a593Smuzhiyun struct buffer_head; 21*4882a593Smuzhiyun 22*4882a593Smuzhiyun struct journal_head { 23*4882a593Smuzhiyun /* 24*4882a593Smuzhiyun * Points back to our buffer_head. [jbd_lock_bh_journal_head()] 25*4882a593Smuzhiyun */ 26*4882a593Smuzhiyun struct buffer_head *b_bh; 27*4882a593Smuzhiyun 28*4882a593Smuzhiyun /* 29*4882a593Smuzhiyun * Protect the buffer head state 30*4882a593Smuzhiyun */ 31*4882a593Smuzhiyun spinlock_t b_state_lock; 32*4882a593Smuzhiyun 33*4882a593Smuzhiyun /* 34*4882a593Smuzhiyun * Reference count - see description in journal.c 35*4882a593Smuzhiyun * [jbd_lock_bh_journal_head()] 36*4882a593Smuzhiyun */ 37*4882a593Smuzhiyun int b_jcount; 38*4882a593Smuzhiyun 39*4882a593Smuzhiyun /* 40*4882a593Smuzhiyun * Journalling list for this buffer [b_state_lock] 41*4882a593Smuzhiyun * NOTE: We *cannot* combine this with b_modified into a bitfield 42*4882a593Smuzhiyun * as gcc would then (which the C standard allows but which is 43*4882a593Smuzhiyun * very unuseful) make 64-bit accesses to the bitfield and clobber 44*4882a593Smuzhiyun * b_jcount if its update races with bitfield modification. 45*4882a593Smuzhiyun */ 46*4882a593Smuzhiyun unsigned b_jlist; 47*4882a593Smuzhiyun 48*4882a593Smuzhiyun /* 49*4882a593Smuzhiyun * This flag signals the buffer has been modified by 50*4882a593Smuzhiyun * the currently running transaction 51*4882a593Smuzhiyun * [b_state_lock] 52*4882a593Smuzhiyun */ 53*4882a593Smuzhiyun unsigned b_modified; 54*4882a593Smuzhiyun 55*4882a593Smuzhiyun /* 56*4882a593Smuzhiyun * Copy of the buffer data frozen for writing to the log. 57*4882a593Smuzhiyun * [b_state_lock] 58*4882a593Smuzhiyun */ 59*4882a593Smuzhiyun char *b_frozen_data; 60*4882a593Smuzhiyun 61*4882a593Smuzhiyun /* 62*4882a593Smuzhiyun * Pointer to a saved copy of the buffer containing no uncommitted 63*4882a593Smuzhiyun * deallocation references, so that allocations can avoid overwriting 64*4882a593Smuzhiyun * uncommitted deletes. [b_state_lock] 65*4882a593Smuzhiyun */ 66*4882a593Smuzhiyun char *b_committed_data; 67*4882a593Smuzhiyun 68*4882a593Smuzhiyun /* 69*4882a593Smuzhiyun * Pointer to the compound transaction which owns this buffer's 70*4882a593Smuzhiyun * metadata: either the running transaction or the committing 71*4882a593Smuzhiyun * transaction (if there is one). Only applies to buffers on a 72*4882a593Smuzhiyun * transaction's data or metadata journaling list. 73*4882a593Smuzhiyun * [j_list_lock] [b_state_lock] 74*4882a593Smuzhiyun * Either of these locks is enough for reading, both are needed for 75*4882a593Smuzhiyun * changes. 76*4882a593Smuzhiyun */ 77*4882a593Smuzhiyun transaction_t *b_transaction; 78*4882a593Smuzhiyun 79*4882a593Smuzhiyun /* 80*4882a593Smuzhiyun * Pointer to the running compound transaction which is currently 81*4882a593Smuzhiyun * modifying the buffer's metadata, if there was already a transaction 82*4882a593Smuzhiyun * committing it when the new transaction touched it. 83*4882a593Smuzhiyun * [t_list_lock] [b_state_lock] 84*4882a593Smuzhiyun */ 85*4882a593Smuzhiyun transaction_t *b_next_transaction; 86*4882a593Smuzhiyun 87*4882a593Smuzhiyun /* 88*4882a593Smuzhiyun * Doubly-linked list of buffers on a transaction's data, metadata or 89*4882a593Smuzhiyun * forget queue. [t_list_lock] [b_state_lock] 90*4882a593Smuzhiyun */ 91*4882a593Smuzhiyun struct journal_head *b_tnext, *b_tprev; 92*4882a593Smuzhiyun 93*4882a593Smuzhiyun /* 94*4882a593Smuzhiyun * Pointer to the compound transaction against which this buffer 95*4882a593Smuzhiyun * is checkpointed. Only dirty buffers can be checkpointed. 96*4882a593Smuzhiyun * [j_list_lock] 97*4882a593Smuzhiyun */ 98*4882a593Smuzhiyun transaction_t *b_cp_transaction; 99*4882a593Smuzhiyun 100*4882a593Smuzhiyun /* 101*4882a593Smuzhiyun * Doubly-linked list of buffers still remaining to be flushed 102*4882a593Smuzhiyun * before an old transaction can be checkpointed. 103*4882a593Smuzhiyun * [j_list_lock] 104*4882a593Smuzhiyun */ 105*4882a593Smuzhiyun struct journal_head *b_cpnext, *b_cpprev; 106*4882a593Smuzhiyun 107*4882a593Smuzhiyun /* Trigger type */ 108*4882a593Smuzhiyun struct jbd2_buffer_trigger_type *b_triggers; 109*4882a593Smuzhiyun 110*4882a593Smuzhiyun /* Trigger type for the committing transaction's frozen data */ 111*4882a593Smuzhiyun struct jbd2_buffer_trigger_type *b_frozen_triggers; 112*4882a593Smuzhiyun }; 113*4882a593Smuzhiyun 114*4882a593Smuzhiyun #endif /* JOURNAL_HEAD_H_INCLUDED */ 115