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-rw-r--r--kernel/include/linux/journal-head.h106
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diff --git a/kernel/include/linux/journal-head.h b/kernel/include/linux/journal-head.h
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+/*
+ * 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
+
+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;
+
+ /*
+ * Reference count - see description in journal.c
+ * [jbd_lock_bh_journal_head()]
+ */
+ int b_jcount;
+
+ /*
+ * Journalling list for this buffer [jbd_lock_bh_state()]
+ * 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
+ * [jbd_lock_bh_state()]
+ */
+ unsigned b_modified;
+
+ /*
+ * Copy of the buffer data frozen for writing to the log.
+ * [jbd_lock_bh_state()]
+ */
+ 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. [jbd_lock_bh_state()]
+ */
+ 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] [jbd_lock_bh_state()]
+ * 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] [jbd_lock_bh_state()]
+ */
+ transaction_t *b_next_transaction;
+
+ /*
+ * Doubly-linked list of buffers on a transaction's data, metadata or
+ * forget queue. [t_list_lock] [jbd_lock_bh_state()]
+ */
+ 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 */