md/raid5: export is_congested test

the dm module will need this for dm-raid45.

Also only access ->queue->backing_dev_info->congested_fn
if ->queue actually exists.  It won't in a dm target.

Signed-off-by: NeilBrown <neilb@suse.de>

2 files changed, 17 insertions, 7 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 9c462f6659c3..ad6694f8a3a8 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3678,17 +3678,14 @@ static void raid5_unplug_device(struct request_queue *q)
         unplug_slaves(mddev);
 }
 
-static int raid5_congested(void *data, int bits)
+int md_raid5_congested(mddev_t *mddev, int bits)
 {
-        mddev_t *mddev = data;
         raid5_conf_t *conf = mddev->private;
 
         /* No difference between reads and writes.  Just check
          * how busy the stripe_cache is
          */
 
-        if (mddev_congested(mddev, bits))
-                return 1;
         if (conf->inactive_blocked)
                 return 1;
         if (conf->quiesce)
@@ -3698,6 +3695,15 @@ static int raid5_congested(void *data, int bits)
 
         return 0;
 }
+EXPORT_SYMBOL_GPL(md_raid5_congested);
+
+static int raid5_congested(void *data, int bits)
+{
+        mddev_t *mddev = data;
+
+        return mddev_congested(mddev, bits) ||
+                md_raid5_congested(mddev, bits);
+}
 
 /* We want read requests to align with chunks where possible,
  * but write requests don't need to.
@@ -5184,13 +5190,14 @@ static int run(mddev_t *mddev)
                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
 
                 blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
+
+                mddev->queue->backing_dev_info.congested_data = mddev;
+                mddev->queue->backing_dev_info.congested_fn = raid5_congested;
         }
 
         mddev->queue->queue_lock = &conf->device_lock;
 
         mddev->queue->unplug_fn = raid5_unplug_device;
-        mddev->queue->backing_dev_info.congested_data = mddev;
-        mddev->queue->backing_dev_info.congested_fn = raid5_congested;
 
         chunk_size = mddev->chunk_sectors << 9;
         blk_queue_io_min(mddev->queue, chunk_size);
@@ -5220,7 +5227,8 @@ static int stop(mddev_t *mddev)
 
         md_unregister_thread(mddev->thread);
         mddev->thread = NULL;
-        mddev->queue->backing_dev_info.congested_fn = NULL;
+        if (mddev->queue)
+                mddev->queue->backing_dev_info.congested_fn = NULL;
         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
         free_conf(conf);
         mddev->private = NULL;
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 61b6b25dc5e7..d6470dec667a 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -497,5 +497,7 @@ static inline int algorithm_is_DDF(int layout)
 {
         return layout >= 8 && layout <= 10;
 }
+
+extern int md_raid5_congested(mddev_t *mddev, int bits);
 extern int raid5_set_cache_size(mddev_t *mddev, int size);
 #endif