src/patches/suse-2.6.27.25/patches.fixes/0005-md-Fix-is_mddev_idle-test-again.patch

   1 From eea1bf384e05b5ab747f8530c4fba9e9e6907fff Mon Sep 17 00:00:00 2001
   2 From: NeilBrown <neilb@suse.de>
   3 Date: Tue, 31 Mar 2009 14:27:02 +1100
   4 Subject: [PATCH] md: Fix is_mddev_idle test (again).
   5
   6 There are two problems with is_mddev_idle.
   7
   8 1/ sync_io is 'atomic_t' and hence 'int'.  curr_events and all the
   9    rest are 'long'.
  10    So if sync_io were to wrap on a 64bit host, the value of
  11    curr_events would go very negative suddenly, and take a very
  12    long time to return to positive.
  13
  14    So do all calculations as 'int'.  That gives us plenty of precision
  15    for what we need.
  16
  17 2/ To initialise rdev->last_events we simply call is_mddev_idle, on
  18    the assumption that it will make sure that last_events is in a
  19    suitable range.  It used to do this, but now it does not.
  20    So now we need to be more explicit about initialisation.
  21
  22 NOTE: to avoid kabi issues in SLES11, we leave 'last_events' as
  23 long and cast it to (int) where used.
  24
  25 Signed-off-by: NeilBrown <neilb@suse.de>
  26 ---
  27  drivers/md/md.c |   10 +++++-----
  28  1 file changed, 5 insertions(+), 5 deletions(-)
  29
  30 --- a/drivers/md/md.c
  31 +++ b/drivers/md/md.c
  32 @@ -5580,11 +5580,11 @@ int unregister_md_personality(struct mdk
  33         return 0;
  34  }
  35
  36 -static int is_mddev_idle(mddev_t *mddev)
  37 +static int is_mddev_idle(mddev_t *mddev, int init)
  38  {
  39         mdk_rdev_t * rdev;
  40         int idle;
  41 -       long curr_events;
  42 +       int curr_events;
  43
  44         idle = 1;
  45         rcu_read_lock();
  46 @@ -5615,7 +5615,7 @@ static int is_mddev_idle(mddev_t *mddev)
  47                  * always make curr_events less than last_events.
  48                  *
  49                  */
  50 -               if (curr_events - rdev->last_events > 4096) {
  51 +               if (init || curr_events - (int)rdev->last_events > 64) {
  52                         rdev->last_events = curr_events;
  53                         idle = 0;
  54                 }
  55 @@ -5859,7 +5859,7 @@ void md_do_sync(mddev_t *mddev)
  56                "(but not more than %d KB/sec) for %s.\n",
  57                speed_max(mddev), desc);
  58
  59 -       is_mddev_idle(mddev); /* this also initializes IO event counters */
  60 +       is_mddev_idle(mddev, 1); /* this initializes IO event counters */
  61
  62         io_sectors = 0;
  63         for (m = 0; m < SYNC_MARKS; m++) {
  64 @@ -5961,7 +5961,7 @@ void md_do_sync(mddev_t *mddev)
  65
  66                 if (currspeed > speed_min(mddev)) {
  67                         if ((currspeed > speed_max(mddev)) ||
  68 -                                       !is_mddev_idle(mddev)) {
  69 +                                       !is_mddev_idle(mddev, 0)) {
  70                                 msleep(500);
  71                                 goto repeat;
  72                         }