drbd: Implemented priority inheritance for resync requests
We only issue resync requests if there is no significant application IO
going on. = Application IO has higher priority than resnyc IO.
If application IO can not be started because the resync process locked
an resync_lru entry, start the IO operations necessary to release the
lock ASAP.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index ee9238e..0630a2e 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -1862,10 +1862,11 @@
* The current sync rate used here uses only the most recent two step marks,
* to have a short time average so we can react faster.
*/
-int drbd_rs_should_slow_down(struct drbd_conf *mdev)
+int drbd_rs_should_slow_down(struct drbd_conf *mdev, sector_t sector)
{
struct gendisk *disk = mdev->ldev->backing_bdev->bd_contains->bd_disk;
unsigned long db, dt, dbdt;
+ struct lc_element *tmp;
int curr_events;
int throttle = 0;
@@ -1873,9 +1874,22 @@
if (mdev->sync_conf.c_min_rate == 0)
return 0;
+ spin_lock_irq(&mdev->al_lock);
+ tmp = lc_find(mdev->resync, BM_SECT_TO_EXT(sector));
+ if (tmp) {
+ struct bm_extent *bm_ext = lc_entry(tmp, struct bm_extent, lce);
+ if (test_bit(BME_PRIORITY, &bm_ext->flags)) {
+ spin_unlock_irq(&mdev->al_lock);
+ return 0;
+ }
+ /* Do not slow down if app IO is already waiting for this extent */
+ }
+ spin_unlock_irq(&mdev->al_lock);
+
curr_events = (int)part_stat_read(&disk->part0, sectors[0]) +
(int)part_stat_read(&disk->part0, sectors[1]) -
atomic_read(&mdev->rs_sect_ev);
+
if (!mdev->rs_last_events || curr_events - mdev->rs_last_events > 64) {
unsigned long rs_left;
int i;
@@ -2060,9 +2074,9 @@
* we would also throttle its application reads.
* In that case, throttling is done on the SyncTarget only.
*/
- if (mdev->state.peer != R_PRIMARY && drbd_rs_should_slow_down(mdev))
- msleep(100);
- if (drbd_rs_begin_io(mdev, e->sector))
+ if (mdev->state.peer != R_PRIMARY && drbd_rs_should_slow_down(mdev, sector))
+ schedule_timeout_uninterruptible(HZ/10);
+ if (drbd_rs_begin_io(mdev, sector))
goto out_free_e;
submit_for_resync:
