jbd2: don't create journal_head for temporary journal buffers

When writing metadata to the journal, we create temporary buffer heads
for that task.  We also attach journal heads to these buffer heads but
the only purpose of the journal heads is to keep buffers linked in
transaction's BJ_IO list.  We remove the need for journal heads by
reusing buffer_head's b_assoc_buffers list for that purpose.  Also
since BJ_IO list is just a temporary list for transaction commit, we
use a private list in jbd2_journal_commit_transaction() for that thus
removing BJ_IO list from transaction completely.

Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 16 insertions, 16 deletions

diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 682a63c..5721084 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -524,12 +524,6 @@ struct transaction_s
 	struct journal_head	*t_checkpoint_io_list;
 
 	/*
-	 * Doubly-linked circular list of temporary buffers currently undergoing
-	 * IO in the log [j_list_lock]
-	 */
-	struct journal_head	*t_iobuf_list;
-
-	/*
 	 * Doubly-linked circular list of metadata buffers being shadowed by log
 	 * IO.  The IO buffers on the iobuf list and the shadow buffers on this
 	 * list match each other one for one at all times. [j_list_lock]
@@ -991,6 +985,14 @@ extern void __jbd2_journal_file_buffer(struct journal_head *, transaction_t *, i
 extern void __journal_free_buffer(struct journal_head *bh);
 extern void jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int);
 extern void __journal_clean_data_list(transaction_t *transaction);
+static inline void jbd2_file_log_bh(struct list_head *head, struct buffer_head *bh)
+{
+	list_add_tail(&bh->b_assoc_buffers, head);
+}
+static inline void jbd2_unfile_log_bh(struct buffer_head *bh)
+{
+	list_del_init(&bh->b_assoc_buffers);
+}
 
 /* Log buffer allocation */
 extern struct journal_head * jbd2_journal_get_descriptor_buffer(journal_t *);
@@ -1039,11 +1041,10 @@ extern void jbd2_buffer_abort_trigger(struct journal_head *jh,
 				      struct jbd2_buffer_trigger_type *triggers);
 
 /* Buffer IO */
-extern int
-jbd2_journal_write_metadata_buffer(transaction_t	  *transaction,
-			      struct journal_head  *jh_in,
-			      struct journal_head **jh_out,
-			      unsigned long long   blocknr);
+extern int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
+					      struct journal_head *jh_in,
+					      struct buffer_head **bh_out,
+					      sector_t blocknr);
 
 /* Transaction locking */
 extern void		__wait_on_journal (journal_t *);
@@ -1286,11 +1287,10 @@ static inline int jbd_space_needed(journal_t *journal)
 #define BJ_None		0	/* Not journaled */
 #define BJ_Metadata	1	/* Normal journaled metadata */
 #define BJ_Forget	2	/* Buffer superseded by this transaction */
-#define BJ_IO		3	/* Buffer is for temporary IO use */
-#define BJ_Shadow	4	/* Buffer contents being shadowed to the log */
-#define BJ_LogCtl	5	/* Buffer contains log descriptors */
-#define BJ_Reserved	6	/* Buffer is reserved for access by journal */
-#define BJ_Types	7
+#define BJ_Shadow	3	/* Buffer contents being shadowed to the log */
+#define BJ_LogCtl	4	/* Buffer contains log descriptors */
+#define BJ_Reserved	5	/* Buffer is reserved for access by journal */
+#define BJ_Types	6
 
 extern int jbd_blocks_per_page(struct inode *inode);