1 files changed, 114 insertions, 0 deletions
diff --git a/include/linux/journal-head.h b/include/linux/journal-head.h
new file mode 100644
index 000000000..75bc56109
--- /dev/null
+++ b/include/linux/journal-head.h
@@ -0,0 +1,114 @@
+/* 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 */