UBIFS: start using hrtimers

UBIFS uses timers for write-buffer write-back. It is not
crucial for us to write-back exactly on time. We are fine
to write-back a little earlier or later. And this means
we may optimize UBIFS timer so that it could be groped
with a close timer event, so that the CPU would not be
waken up just to do the write back. This is optimization
to lessen power consumption, which is important in
embedded devices UBIFS is used for.

hrtimers have a nice feature: they are effectively range
timers, and we may defind the soft and hard limits for
it. Standard timers do not have these feature. They may
only be made deferrable, but this means there is effectively
no hard limit. So, we will better use hrtimers.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index b9b051a..91c91cb 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -799,7 +799,7 @@ static int alloc_wbufs(struct ubifs_info *c)
 	 * does not need to be synchronized by timer.
 	 */
 	c->jheads[GCHD].wbuf.dtype = UBI_LONGTERM;
-	c->jheads[GCHD].wbuf.timeout = 0;
+	c->jheads[GCHD].wbuf.softlimit = ktime_set(0, 0);
 
 	return 0;
 }
@@ -1695,7 +1695,7 @@ static void ubifs_remount_ro(struct ubifs_info *c)
 
 	for (i = 0; i < c->jhead_cnt; i++) {
 		ubifs_wbuf_sync(&c->jheads[i].wbuf);
-		del_timer_sync(&c->jheads[i].wbuf.timer);
+		hrtimer_cancel(&c->jheads[i].wbuf.timer);
 	}
 
 	c->mst_node->flags &= ~cpu_to_le32(UBIFS_MST_DIRTY);
@@ -1755,7 +1755,7 @@ static void ubifs_put_super(struct super_block *sb)
 		if (c->jheads)
 			for (i = 0; i < c->jhead_cnt; i++) {
 				ubifs_wbuf_sync(&c->jheads[i].wbuf);
-				del_timer_sync(&c->jheads[i].wbuf.timer);
+				hrtimer_cancel(&c->jheads[i].wbuf.timer);
 			}
 
 		/*