From eea1bf384e05b5ab747f8530c4fba9e9e6907fff Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 31 Mar 2009 14:27:02 +1100 Subject: md: Fix is_mddev_idle test (again). There are two problems with is_mddev_idle. 1/ sync_io is 'atomic_t' and hence 'int'. curr_events and all the rest are 'long'. So if sync_io were to wrap on a 64bit host, the value of curr_events would go very negative suddenly, and take a very long time to return to positive. So do all calculations as 'int'. That gives us plenty of precision for what we need. 2/ To initialise rdev->last_events we simply call is_mddev_idle, on the assumption that it will make sure that last_events is in a suitable range. It used to do this, but now it does not. So now we need to be more explicit about initialisation. Signed-off-by: NeilBrown --- drivers/md/md.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) (limited to 'drivers/md') diff --git a/drivers/md/md.c b/drivers/md/md.c index 03b4cd0a634..a99c50e217c 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -5716,19 +5716,19 @@ int unregister_md_personality(struct mdk_personality *p) return 0; } -static int is_mddev_idle(mddev_t *mddev) +static int is_mddev_idle(mddev_t *mddev, int init) { mdk_rdev_t * rdev; int idle; - long curr_events; + int curr_events; idle = 1; rcu_read_lock(); rdev_for_each_rcu(rdev, mddev) { struct gendisk *disk = rdev->bdev->bd_contains->bd_disk; - curr_events = part_stat_read(&disk->part0, sectors[0]) + - part_stat_read(&disk->part0, sectors[1]) - - atomic_read(&disk->sync_io); + curr_events = (int)part_stat_read(&disk->part0, sectors[0]) + + (int)part_stat_read(&disk->part0, sectors[1]) - + atomic_read(&disk->sync_io); /* sync IO will cause sync_io to increase before the disk_stats * as sync_io is counted when a request starts, and * disk_stats is counted when it completes. @@ -5751,7 +5751,7 @@ static int is_mddev_idle(mddev_t *mddev) * always make curr_events less than last_events. * */ - if (curr_events - rdev->last_events > 4096) { + if (init || curr_events - rdev->last_events > 64) { rdev->last_events = curr_events; idle = 0; } @@ -5994,7 +5994,7 @@ void md_do_sync(mddev_t *mddev) "(but not more than %d KB/sec) for %s.\n", speed_max(mddev), desc); - is_mddev_idle(mddev); /* this also initializes IO event counters */ + is_mddev_idle(mddev, 1); /* this initializes IO event counters */ io_sectors = 0; for (m = 0; m < SYNC_MARKS; m++) { @@ -6096,7 +6096,7 @@ void md_do_sync(mddev_t *mddev) if (currspeed > speed_min(mddev)) { if ((currspeed > speed_max(mddev)) || - !is_mddev_idle(mddev)) { + !is_mddev_idle(mddev, 0)) { msleep(500); goto repeat; } -- cgit v1.2.3