Commit:     435b71be20f2ad3688acd94c05e968e029464d60
Parent:     11fe250d89cdce3d6bb43bd674f3dcdcaa78dbc8
Author:     NeilBrown <[EMAIL PROTECTED]>
AuthorDate: Thu May 10 22:23:31 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Fri May 11 08:29:37 2007 -0700

    md: improve the is_mddev_idle test
    During a 'resync' or similar activity, md checks if the devices in the
    array are otherwise active and winds back resync activity when they are.
    This test in done in is_mddev_idle, and it is somewhat fragile - it
    sometimes thinks there is non-sync io when there isn't.
    The test compares the total sectors of io (disk_stat_read) with the sectors
    of resync io (disk->sync_io).  This has problems because total sectors gets
    updated when a request completes, while resync io gets updated when the
    request is submitted.  The time difference can cause large differenced
    between the two which do not actually imply non-resync activity.  The test
    currently allows for some fuzz (+/- 4096) but there are some cases when it
    is not enough.
    The test currently looks for any (non-fuzz) difference, either positive or
    negative.  This clearly is not needed.  Any non-sync activity will cause
    the total sectors to grow faster than the sync_io count (never slower) so
    we only need to look for a positive differences.
    If we do this then the amount of in-flight sync io will never cause the
    appearance of non-sync IO.  Once enough non-sync IO to worry about starts
    happening, resync will be slowed down and the measurements will thus be
    more precise (as there is less in-flight) and control of resync will still
    be suitably responsive.
    Signed-off-by: Neil Brown <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
 drivers/md/md.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 65814b0..c10ce91 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5103,7 +5103,7 @@ static int is_mddev_idle(mddev_t *mddev)
                 * Note: the following is an unsigned comparison.
-               if ((curr_events - rdev->last_events + 4096) > 8192) {
+               if ((long)curr_events - (long)rdev->last_events > 4096) {
                        rdev->last_events = curr_events;
                        idle = 0;
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