[PATCH] JBD: split checkpoint lists

Split the checkpoint list of the transaction into two lists.  In the first
list we keep the buffers that need to be submitted for IO.  In the second
list are kept buffers that were already submitted and we just have to wait
for the IO to complete.  This should simplify a handling of checkpoint
lists a bit and can eventually be also a performance gain.
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Mark Fasheh <mark.fasheh@oracle.com>
Cc: "Stephen C. Tweedie" <sct@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/jbd.h

@@ -500,6 +500,12 @@ struct transaction_s
 	 */
 	struct journal_head	*t_checkpoint_list;
 
+	/*
+	 * Doubly-linked circular list of all buffers submitted for IO while
+	 * checkpointing. [j_list_lock]
+	 */
+	struct journal_head	*t_checkpoint_io_list;
+
 	/*
 	 * Doubly-linked circular list of temporary buffers currently undergoing
 	 * IO in the log [j_list_lock]
@@ -849,7 +855,7 @@ extern void journal_commit_transaction(journal_t *);
 
 /* Checkpoint list management */
 int __journal_clean_checkpoint_list(journal_t *journal);
-void __journal_remove_checkpoint(struct journal_head *);
+int __journal_remove_checkpoint(struct journal_head *);
 void __journal_insert_checkpoint(struct journal_head *, transaction_t *);
 
 /* Buffer IO */