writeback: remove bdi->congested_fn

Except for pktdvd, the only places setting congested bits are file
systems that allocate their own backing_dev_info structures.  And
pktdvd is a deprecated driver that isn't useful in stack setup
either.  So remove the dead congested_fn stacking infrastructure.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Song Liu <song@kernel.org>
Acked-by: David Sterba <dsterba@suse.com>
[axboe: fixup unused variables in bcache/request.c]
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/drbd/drbd_main.c

@@ -2415,62 +2415,6 @@ static void drbd_cleanup(void)
 	pr_info("module cleanup done.\n");
 }
 
-/**
- * drbd_congested() - Callback for the flusher thread
- * @congested_data:	User data
- * @bdi_bits:		Bits the BDI flusher thread is currently interested in
- *
- * Returns 1<<WB_async_congested and/or 1<<WB_sync_congested if we are congested.
- */
-static int drbd_congested(void *congested_data, int bdi_bits)
-{
-	struct drbd_device *device = congested_data;
-	struct request_queue *q;
-	char reason = '-';
-	int r = 0;
-
-	if (!may_inc_ap_bio(device)) {
-		/* DRBD has frozen IO */
-		r = bdi_bits;
-		reason = 'd';
-		goto out;
-	}
-
-	if (test_bit(CALLBACK_PENDING, &first_peer_device(device)->connection->flags)) {
-		r |= (1 << WB_async_congested);
-		/* Without good local data, we would need to read from remote,
-		 * and that would need the worker thread as well, which is
-		 * currently blocked waiting for that usermode helper to
-		 * finish.
-		 */
-		if (!get_ldev_if_state(device, D_UP_TO_DATE))
-			r |= (1 << WB_sync_congested);
-		else
-			put_ldev(device);
-		r &= bdi_bits;
-		reason = 'c';
-		goto out;
-	}
-
-	if (get_ldev(device)) {
-		q = bdev_get_queue(device->ldev->backing_bdev);
-		r = bdi_congested(q->backing_dev_info, bdi_bits);
-		put_ldev(device);
-		if (r)
-			reason = 'b';
-	}
-
-	if (bdi_bits & (1 << WB_async_congested) &&
-	    test_bit(NET_CONGESTED, &first_peer_device(device)->connection->flags)) {
-		r |= (1 << WB_async_congested);
-		reason = reason == 'b' ? 'a' : 'n';
-	}
-
-out:
-	device->congestion_reason = reason;
-	return r;
-}
-
 static void drbd_init_workqueue(struct drbd_work_queue* wq)
 {
 	spin_lock_init(&wq->q_lock);
@@ -2825,9 +2769,6 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig
 	/* we have no partitions. we contain only ourselves. */
 	device->this_bdev->bd_contains = device->this_bdev;
 
-	q->backing_dev_info->congested_fn = drbd_congested;
-	q->backing_dev_info->congested_data = device;
-
 	blk_queue_write_cache(q, true, true);
 	/* Setting the max_hw_sectors to an odd value of 8kibyte here
 	   This triggers a max_bio_size message upon first attach or connect */

drivers/md/bcache/request.c

@@ -1228,36 +1228,8 @@ static int cached_dev_ioctl(struct bcache_device *d, fmode_t mode,
 	return __blkdev_driver_ioctl(dc->bdev, mode, cmd, arg);
 }
 
-static int cached_dev_congested(void *data, int bits)
-{
-	struct bcache_device *d = data;
-	struct cached_dev *dc = container_of(d, struct cached_dev, disk);
-	struct request_queue *q = bdev_get_queue(dc->bdev);
-	int ret = 0;
-
-	if (bdi_congested(q->backing_dev_info, bits))
-		return 1;
-
-	if (cached_dev_get(dc)) {
-		unsigned int i;
-		struct cache *ca;
-
-		for_each_cache(ca, d->c, i) {
-			q = bdev_get_queue(ca->bdev);
-			ret |= bdi_congested(q->backing_dev_info, bits);
-		}
-
-		cached_dev_put(dc);
-	}
-
-	return ret;
-}
-
 void bch_cached_dev_request_init(struct cached_dev *dc)
 {
-	struct gendisk *g = dc->disk.disk;
-
-	g->queue->backing_dev_info->congested_fn = cached_dev_congested;
 	dc->disk.cache_miss			= cached_dev_cache_miss;
 	dc->disk.ioctl				= cached_dev_ioctl;
 }
@@ -1341,27 +1313,8 @@ static int flash_dev_ioctl(struct bcache_device *d, fmode_t mode,
 	return -ENOTTY;
 }
 
-static int flash_dev_congested(void *data, int bits)
-{
-	struct bcache_device *d = data;
-	struct request_queue *q;
-	struct cache *ca;
-	unsigned int i;
-	int ret = 0;
-
-	for_each_cache(ca, d->c, i) {
-		q = bdev_get_queue(ca->bdev);
-		ret |= bdi_congested(q->backing_dev_info, bits);
-	}
-
-	return ret;
-}
-
 void bch_flash_dev_request_init(struct bcache_device *d)
 {
-	struct gendisk *g = d->disk;
-
-	g->queue->backing_dev_info->congested_fn = flash_dev_congested;
 	d->cache_miss				= flash_dev_cache_miss;
 	d->ioctl				= flash_dev_ioctl;
 }

drivers/md/bcache/super.c

@@ -885,7 +885,6 @@ static int bcache_device_init(struct bcache_device *d, unsigned int block_size,
 		return -ENOMEM;
 
 	d->disk->queue			= q;
-	q->backing_dev_info->congested_data = d;
 	q->limits.max_hw_sectors	= UINT_MAX;
 	q->limits.max_sectors		= UINT_MAX;
 	q->limits.max_segment_size	= UINT_MAX;

drivers/md/dm-cache-target.c

@@ -421,8 +421,6 @@ struct cache {
 
 	struct rw_semaphore quiesce_lock;
 
-	struct dm_target_callbacks callbacks;
-
 	/*
 	 * origin_blocks entries, discarded if set.
 	 */
@@ -2423,20 +2421,6 @@ static void set_cache_size(struct cache *cache, dm_cblock_t size)
 	cache->cache_size = size;
 }
 
-static int is_congested(struct dm_dev *dev, int bdi_bits)
-{
-	struct request_queue *q = bdev_get_queue(dev->bdev);
-	return bdi_congested(q->backing_dev_info, bdi_bits);
-}
-
-static int cache_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
-{
-	struct cache *cache = container_of(cb, struct cache, callbacks);
-
-	return is_congested(cache->origin_dev, bdi_bits) ||
-		is_congested(cache->cache_dev, bdi_bits);
-}
-
 #define DEFAULT_MIGRATION_THRESHOLD 2048
 
 static int cache_create(struct cache_args *ca, struct cache **result)
@@ -2471,9 +2455,6 @@ static int cache_create(struct cache_args *ca, struct cache **result)
 			goto bad;
 	}
 
-	cache->callbacks.congested_fn = cache_is_congested;
-	dm_table_add_target_callbacks(ti->table, &cache->callbacks);
-
 	cache->metadata_dev = ca->metadata_dev;
 	cache->origin_dev = ca->origin_dev;
 	cache->cache_dev = ca->cache_dev;

drivers/md/dm-clone-target.c

@@ -68,7 +68,6 @@ struct hash_table_bucket;
 
 struct clone {
 	struct dm_target *ti;
-	struct dm_target_callbacks callbacks;
 
 	struct dm_dev *metadata_dev;
 	struct dm_dev *dest_dev;
@@ -1518,18 +1517,6 @@ static void clone_status(struct dm_target *ti, status_type_t type,
 	DMEMIT("Error");
 }
 
-static int clone_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
-{
-	struct request_queue *dest_q, *source_q;
-	struct clone *clone = container_of(cb, struct clone, callbacks);
-
-	source_q = bdev_get_queue(clone->source_dev->bdev);
-	dest_q = bdev_get_queue(clone->dest_dev->bdev);
-
-	return (bdi_congested(dest_q->backing_dev_info, bdi_bits) |
-		bdi_congested(source_q->backing_dev_info, bdi_bits));
-}
-
 static sector_t get_dev_size(struct dm_dev *dev)
 {
 	return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
@@ -1930,8 +1917,6 @@ static int clone_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		goto out_with_mempool;
 
 	mutex_init(&clone->commit_lock);
-	clone->callbacks.congested_fn = clone_is_congested;
-	dm_table_add_target_callbacks(ti->table, &clone->callbacks);
 
 	/* Enable flushes */
 	ti->num_flush_bios = 1;

drivers/md/dm-era-target.c

@@ -1137,7 +1137,6 @@ static int metadata_get_stats(struct era_metadata *md, void *ptr)
 
 struct era {
 	struct dm_target *ti;
-	struct dm_target_callbacks callbacks;
 
 	struct dm_dev *metadata_dev;
 	struct dm_dev *origin_dev;
@@ -1375,18 +1374,6 @@ static void stop_worker(struct era *era)
 /*----------------------------------------------------------------
  * Target methods
  *--------------------------------------------------------------*/
-static int dev_is_congested(struct dm_dev *dev, int bdi_bits)
-{
-	struct request_queue *q = bdev_get_queue(dev->bdev);
-	return bdi_congested(q->backing_dev_info, bdi_bits);
-}
-
-static int era_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
-{
-	struct era *era = container_of(cb, struct era, callbacks);
-	return dev_is_congested(era->origin_dev, bdi_bits);
-}
-
 static void era_destroy(struct era *era)
 {
 	if (era->md)
@@ -1514,8 +1501,6 @@ static int era_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	ti->flush_supported = true;
 
 	ti->num_discard_bios = 1;
-	era->callbacks.congested_fn = era_is_congested;
-	dm_table_add_target_callbacks(ti->table, &era->callbacks);
 
 	return 0;
 }

drivers/md/dm-raid.c

@@ -242,7 +242,6 @@ struct raid_set {
 
 	struct mddev md;
 	struct raid_type *raid_type;
-	struct dm_target_callbacks callbacks;
 
 	sector_t array_sectors;
 	sector_t dev_sectors;
@@ -1705,13 +1704,6 @@ static void do_table_event(struct work_struct *ws)
 	dm_table_event(rs->ti->table);
 }
 
-static int raid_is_congested(struct dm_target_callbacks *cb, int bits)
-{
-	struct raid_set *rs = container_of(cb, struct raid_set, callbacks);
-
-	return mddev_congested(&rs->md, bits);
-}
-
 /*
  * Make sure a valid takover (level switch) is being requested on @rs
  *
@@ -3248,9 +3240,6 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		goto bad_md_start;
 	}
 
-	rs->callbacks.congested_fn = raid_is_congested;
-	dm_table_add_target_callbacks(ti->table, &rs->callbacks);
-
 	/* If raid4/5/6 journal mode explicitly requested (only possible with journal dev) -> set it */
 	if (test_bit(__CTR_FLAG_JOURNAL_MODE, &rs->ctr_flags)) {
 		r = r5c_journal_mode_set(&rs->md, rs->journal_dev.mode);
@@ -3310,7 +3299,6 @@ static void raid_dtr(struct dm_target *ti)
 {
 	struct raid_set *rs = ti->private;
 
-	list_del_init(&rs->callbacks.list);
 	md_stop(&rs->md);
 	raid_set_free(rs);
 }

drivers/md/dm-table.c

@@ -64,8 +64,6 @@ struct dm_table {
 	void *event_context;
 
 	struct dm_md_mempools *mempools;
-
-	struct list_head target_callbacks;
 };
 
 /*
@@ -190,7 +188,6 @@ int dm_table_create(struct dm_table **result, fmode_t mode,
 		return -ENOMEM;
 
 	INIT_LIST_HEAD(&t->devices);
-	INIT_LIST_HEAD(&t->target_callbacks);
 
 	if (!num_targets)
 		num_targets = KEYS_PER_NODE;
@@ -361,7 +358,7 @@ static int device_area_is_invalid(struct dm_target *ti, struct dm_dev *dev,
  * This upgrades the mode on an already open dm_dev, being
  * careful to leave things as they were if we fail to reopen the
  * device and not to touch the existing bdev field in case
- * it is accessed concurrently inside dm_table_any_congested().
+ * it is accessed concurrently.
  */
 static int upgrade_mode(struct dm_dev_internal *dd, fmode_t new_mode,
 			struct mapped_device *md)
@@ -2052,38 +2049,6 @@ int dm_table_resume_targets(struct dm_table *t)
 	return 0;
 }
 
-void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb)
-{
-	list_add(&cb->list, &t->target_callbacks);
-}
-EXPORT_SYMBOL_GPL(dm_table_add_target_callbacks);
-
-int dm_table_any_congested(struct dm_table *t, int bdi_bits)
-{
-	struct dm_dev_internal *dd;
-	struct list_head *devices = dm_table_get_devices(t);
-	struct dm_target_callbacks *cb;
-	int r = 0;
-
-	list_for_each_entry(dd, devices, list) {
-		struct request_queue *q = bdev_get_queue(dd->dm_dev->bdev);
-		char b[BDEVNAME_SIZE];
-
-		if (likely(q))
-			r |= bdi_congested(q->backing_dev_info, bdi_bits);
-		else
-			DMWARN_LIMIT("%s: any_congested: nonexistent device %s",
-				     dm_device_name(t->md),
-				     bdevname(dd->dm_dev->bdev, b));
-	}
-
-	list_for_each_entry(cb, &t->target_callbacks, list)
-		if (cb->congested_fn)
-			r |= cb->congested_fn(cb, bdi_bits);
-
-	return r;
-}
-
 struct mapped_device *dm_table_get_md(struct dm_table *t)
 {
 	return t->md;

drivers/md/dm-thin.c

@@ -326,7 +326,6 @@ struct pool_c {
 	struct pool *pool;
 	struct dm_dev *data_dev;
 	struct dm_dev *metadata_dev;
-	struct dm_target_callbacks callbacks;
 
 	dm_block_t low_water_blocks;
 	struct pool_features requested_pf; /* Features requested during table load */
@@ -2796,18 +2795,6 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
 	}
 }
 
-static int pool_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
-{
-	struct pool_c *pt = container_of(cb, struct pool_c, callbacks);
-	struct request_queue *q;
-
-	if (get_pool_mode(pt->pool) == PM_OUT_OF_DATA_SPACE)
-		return 1;
-
-	q = bdev_get_queue(pt->data_dev->bdev);
-	return bdi_congested(q->backing_dev_info, bdi_bits);
-}
-
 static void requeue_bios(struct pool *pool)
 {
 	struct thin_c *tc;
@@ -3420,9 +3407,6 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	dm_pool_register_pre_commit_callback(pool->pmd,
 					     metadata_pre_commit_callback, pool);
 
-	pt->callbacks.congested_fn = pool_is_congested;
-	dm_table_add_target_callbacks(ti->table, &pt->callbacks);
-
 	mutex_unlock(&dm_thin_pool_table.mutex);
 
 	return 0;