UBIFS: slightly optimize write-buffer timer usage

This patch adds the following minor optimization:

1. If write-buffer does not use the timer, indicate it with the
   wbuf->no_timer variable, instead of using the wbuf->softlimit
   variable. This is better because wbuf->softlimit is of ktime_t
   type, and the ktime_to_ns function contains 64-bit multiplication.

2. Do not call the 'hrtimer_cancel()' function for write-buffers
   which do not use timers.

3. Do not cancel the timer in 'ubifs_put_super()' because the
   synchronization function does this.

This patch also removes a confusing comment.

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

1 files changed, 3 insertions, 6 deletions

diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c
index 2ef689a9a363..9fcf6c38c1bc 100644
--- a/fs/ubifs/io.c
+++ b/fs/ubifs/io.c
@@ -312,7 +312,7 @@ static void new_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
 {
         ubifs_assert(!hrtimer_active(&wbuf->timer));
 
-        if (!ktime_to_ns(wbuf->softlimit))
+        if (wbuf->no_timer)
                 return;
         dbg_io("set timer for jhead %d, %llu-%llu millisecs", wbuf->jhead,
                ktime_to_ns(wbuf->softlimit)/USEC_PER_SEC,
@@ -327,11 +327,8 @@ static void new_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
  */
 static void cancel_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
 {
-        /*
-         * If the syncer is waiting for the lock (from the background thread's
-         * context) and another task is changing write-buffer then the syncing
-         * should be canceled.
-         */
+        if (wbuf->no_timer)
+                return;
         wbuf->need_sync = 0;
         hrtimer_cancel(&wbuf->timer);
 }