[PATCH] md: define backing_dev_info.congested_fn for raid0 and linear

Each backing_dev needs to be able to report whether it is congested, either by
modulating BDI_*_congested in ->state, or by defining a ->congested_fn.
md/raid did neither of these.  This patch add a congested_fn which simply
checks all component devices to see if they are congested.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index b99c19c7eb22..c625ddb8833d 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -111,6 +111,19 @@ static int linear_issue_flush(request_queue_t *q, struct gendisk *disk,
         return ret;
 }
 
+static int linear_congested(void *data, int bits)
+{
+        mddev_t *mddev = data;
+        linear_conf_t *conf = mddev_to_conf(mddev);
+        int i, ret = 0;
+
+        for (i = 0; i < mddev->raid_disks && !ret ; i++) {
+                request_queue_t *q = bdev_get_queue(conf->disks[i].rdev->bdev);
+                ret |= bdi_congested(&q->backing_dev_info, bits);
+        }
+        return ret;
+}
+
 static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
 {
         linear_conf_t *conf;
@@ -269,6 +282,8 @@ static int linear_run (mddev_t *mddev)
         blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
         mddev->queue->unplug_fn = linear_unplug;
         mddev->queue->issue_flush_fn = linear_issue_flush;
+        mddev->queue->backing_dev_info.congested_fn = linear_congested;
+        mddev->queue->backing_dev_info.congested_data = mddev;
         return 0;
 }