[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 f785cf26cbad..cfe60cfc8f3d 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;
 };