[PATCH] md: define ->congested_fn for raid1, raid10, and multipath
raid1, raid10 and multipath don't report their 'congested' status through
bdi_*_congested, but should.
This patch adds the appropriate functions which just check the 'congested'
status of all active members (with appropriate locking).
raid1 read_balance should be modified to prefer devices where
bdi_read_congested returns false. Then we could use the '&' branch rather
than the '|' branch. However that should would need some benchmarking first
to make sure it is actually a good idea.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 99c4e03..dc9d2de 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -601,6 +601,32 @@
return ret;
}
+static int raid1_congested(void *data, int bits)
+{
+ mddev_t *mddev = data;
+ conf_t *conf = mddev_to_conf(mddev);
+ int i, ret = 0;
+
+ rcu_read_lock();
+ for (i = 0; i < mddev->raid_disks; i++) {
+ mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
+ if (rdev && !test_bit(Faulty, &rdev->flags)) {
+ request_queue_t *q = bdev_get_queue(rdev->bdev);
+
+ /* Note the '|| 1' - when read_balance prefers
+ * non-congested targets, it can be removed
+ */
+ if ((bits & (1<<BDI_write_congested)) || 1)
+ ret |= bdi_congested(&q->backing_dev_info, bits);
+ else
+ ret &= bdi_congested(&q->backing_dev_info, bits);
+ }
+ }
+ rcu_read_unlock();
+ return ret;
+}
+
+
/* Barriers....
* Sometimes we need to suspend IO while we do something else,
* either some resync/recovery, or reconfigure the array.
@@ -1965,6 +1991,8 @@
mddev->queue->unplug_fn = raid1_unplug;
mddev->queue->issue_flush_fn = raid1_issue_flush;
+ mddev->queue->backing_dev_info.congested_fn = raid1_congested;
+ mddev->queue->backing_dev_info.congested_data = mddev;
return 0;
