linux-kernel - [PATCH 002 of 2] md: Reduce CPU wastage on idle md array with a write-intent bitmap. fix

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Message-Id:  <1080307050053.26127@suse.de>
Date:	Fri, 7 Mar 2008 16:00:53 +1100
From:	NeilBrown <neilb@...e.de>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 002 of 2] md: Reduce CPU wastage on idle md array with a write-intent bitmap. fix

Recent patch titled
  Reduce CPU wastage on idle md array with a write-intent bitmap.

would sometimes leave the array with dirty bitmap bits that stay
dirty.  A subsequent write would sort things out so it isn't a big
problem, but should be fixed nonetheless.

We need to make sure that when the bitmap becomes not "allclean", the
daemon_sleep really does get set to a sensible value.

Signed-off-by: Neil Brown <neilb@...e.de>

### Diffstat output
 ./drivers/md/bitmap.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff .prev/drivers/md/bitmap.c ./drivers/md/bitmap.c
--- .prev/drivers/md/bitmap.c	2008-03-07 15:51:23.000000000 +1100
+++ ./drivers/md/bitmap.c	2008-03-07 15:56:57.000000000 +1100
@@ -1045,7 +1045,8 @@ void bitmap_daemon_work(struct bitmap *b
 	if (bitmap == NULL)
 		return;
 	if (time_before(jiffies, bitmap->daemon_lastrun + bitmap->daemon_sleep*HZ))
-		return;
+		goto done;
+
 	bitmap->daemon_lastrun = jiffies;
 	if (bitmap->allclean) {
 		bitmap->mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
@@ -1142,6 +1143,7 @@ void bitmap_daemon_work(struct bitmap *b
 		}
 	}

+ done:
 	if (bitmap->allclean == 0)
 		bitmap->mddev->thread->timeout = bitmap->daemon_sleep * HZ;
 }
--
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