[PATCH] md: enable the bitmap write-back daemon and wait for it.

Currently we don't wait for updates to the bitmap to be flushed to disk
properly.  The infrastructure all there, but it isn't being used....

A separate kernel thread (bitmap_writeback_daemon) is needed to wait for each
page as we cannot get callbacks when a page write completes.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 11 deletions

diff --git a/include/linux/raid/bitmap.h b/include/linux/raid/bitmap.h
index f785cf26cba..cfe60cfc8f3 100644
--- a/include/linux/raid/bitmap.h
+++ b/include/linux/raid/bitmap.h
@@ -233,21 +233,12 @@ struct bitmap {
 	unsigned long daemon_sleep; /* how many seconds between updates? */
 
 	/*
-	 * bitmap write daemon - this daemon performs writes to the bitmap file
-	 * this thread is only needed because of a limitation in ext3 (jbd)
-	 * that does not allow a task to have two journal transactions ongoing
-	 * simultaneously (even if the transactions are for two different
-	 * filesystems) -- in the case of bitmap, that would be the filesystem
-	 * that the bitmap file resides on and the filesystem that is mounted
-	 * on the md device -- see current->journal_info in jbd/transaction.c
+	 * bitmap_writeback_daemon waits for file-pages that have been written,
+	 * as there is no way to get a call-back when a page write completes.
 	 */
 	mdk_thread_t *writeback_daemon;
 	spinlock_t write_lock;
-	struct semaphore write_ready;
-	struct semaphore write_done;
-	unsigned long writes_pending;
 	wait_queue_head_t write_wait;
-	struct list_head write_pages;
 	struct list_head complete_pages;
 	mempool_t *write_pool;
 };