dm: table use list_for_each

This patch is some minor janitorish cleanup, using some macros
from linux/list.h (already #included via dm.h) to improve
readability.
Signed-off-by: NPaul Jimenez <pj@place.org>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

drivers/md/dm-table.c

@@ -287,9 +287,8 @@ static void free_devices(struct list_head *devices)
 {
 	struct list_head *tmp, *next;
 
-	for (tmp = devices->next; tmp != devices; tmp = next) {
+	list_for_each_safe(tmp, next, devices) {
 		struct dm_dev *dd = list_entry(tmp, struct dm_dev, list);
-		next = tmp->next;
 		kfree(dd);
 	}
 }
@@ -993,12 +992,11 @@ int dm_table_resume_targets(struct dm_table *t)
 
 int dm_table_any_congested(struct dm_table *t, int bdi_bits)
 {
-	struct list_head *d, *devices;
+	struct dm_dev *dd;
+	struct list_head *devices = dm_table_get_devices(t);
 	int r = 0;
 
-	devices = dm_table_get_devices(t);
-	for (d = devices->next; d != devices; d = d->next) {
-		struct dm_dev *dd = list_entry(d, struct dm_dev, list);
+	list_for_each_entry(dd, devices, list) {
 		struct request_queue *q = bdev_get_queue(dd->bdev);
 		r |= bdi_congested(&q->backing_dev_info, bdi_bits);
 	}
@@ -1008,10 +1006,10 @@ int dm_table_any_congested(struct dm_table *t, int bdi_bits)
 
 void dm_table_unplug_all(struct dm_table *t)
 {
-	struct list_head *d, *devices = dm_table_get_devices(t);
+	struct dm_dev *dd;
+	struct list_head *devices = dm_table_get_devices(t);
 
-	for (d = devices->next; d != devices; d = d->next) {
-		struct dm_dev *dd = list_entry(d, struct dm_dev, list);
+	list_for_each_entry(dd, devices, list) {
 		struct request_queue *q = bdev_get_queue(dd->bdev);
 
 		blk_unplug(q);