| /* SPDX-License-Identifier: GPL-2.0 */ |
| /* |
| * include/linux/journal-head.h |
| * |
| * buffer_head fields for JBD |
| * |
| * 27 May 2001 Andrew Morton |
| * Created - pulled out of fs.h |
| */ |
| |
| #ifndef JOURNAL_HEAD_H_INCLUDED |
| #define JOURNAL_HEAD_H_INCLUDED |
| |
| #include <linux/spinlock.h> |
| |
| typedef unsigned int tid_t; /* Unique transaction ID */ |
| typedef struct transaction_s transaction_t; /* Compound transaction type */ |
| |
| |
| struct buffer_head; |
| |
| struct journal_head { |
| /* |
| * Points back to our buffer_head. [jbd_lock_bh_journal_head()] |
| */ |
| struct buffer_head *b_bh; |
| |
| /* |
| * Protect the buffer head state |
| */ |
| spinlock_t b_state_lock; |
| |
| /* |
| * Reference count - see description in journal.c |
| * [jbd_lock_bh_journal_head()] |
| */ |
| int b_jcount; |
| |
| /* |
| * Journalling list for this buffer [b_state_lock] |
| * NOTE: We *cannot* combine this with b_modified into a bitfield |
| * as gcc would then (which the C standard allows but which is |
| * very unuseful) make 64-bit accesses to the bitfield and clobber |
| * b_jcount if its update races with bitfield modification. |
| */ |
| unsigned b_jlist; |
| |
| /* |
| * This flag signals the buffer has been modified by |
| * the currently running transaction |
| * [b_state_lock] |
| */ |
| unsigned b_modified; |
| |
| /* |
| * Copy of the buffer data frozen for writing to the log. |
| * [b_state_lock] |
| */ |
| char *b_frozen_data; |
| |
| /* |
| * Pointer to a saved copy of the buffer containing no uncommitted |
| * deallocation references, so that allocations can avoid overwriting |
| * uncommitted deletes. [b_state_lock] |
| */ |
| char *b_committed_data; |
| |
| /* |
| * Pointer to the compound transaction which owns this buffer's |
| * metadata: either the running transaction or the committing |
| * transaction (if there is one). Only applies to buffers on a |
| * transaction's data or metadata journaling list. |
| * [j_list_lock] [b_state_lock] |
| * Either of these locks is enough for reading, both are needed for |
| * changes. |
| */ |
| transaction_t *b_transaction; |
| |
| /* |
| * Pointer to the running compound transaction which is currently |
| * modifying the buffer's metadata, if there was already a transaction |
| * committing it when the new transaction touched it. |
| * [t_list_lock] [b_state_lock] |
| */ |
| transaction_t *b_next_transaction; |
| |
| /* |
| * Doubly-linked list of buffers on a transaction's data, metadata or |
| * forget queue. [t_list_lock] [b_state_lock] |
| */ |
| struct journal_head *b_tnext, *b_tprev; |
| |
| /* |
| * Pointer to the compound transaction against which this buffer |
| * is checkpointed. Only dirty buffers can be checkpointed. |
| * [j_list_lock] |
| */ |
| transaction_t *b_cp_transaction; |
| |
| /* |
| * Doubly-linked list of buffers still remaining to be flushed |
| * before an old transaction can be checkpointed. |
| * [j_list_lock] |
| */ |
| struct journal_head *b_cpnext, *b_cpprev; |
| |
| /* Trigger type */ |
| struct jbd2_buffer_trigger_type *b_triggers; |
| |
| /* Trigger type for the committing transaction's frozen data */ |
| struct jbd2_buffer_trigger_type *b_frozen_triggers; |
| }; |
| |
| #endif /* JOURNAL_HEAD_H_INCLUDED */ |