dm: disable interrupt when taking map_lock

This patch disables interrupt when taking map_lock to avoid
lockdep warnings in request-based dm.

request-based dm takes map_lock after taking queue_lock with
disabling interrupt:
  spin_lock_irqsave(queue_lock)
  q->request_fn() == dm_request_fn()
    => dm_get_table()
         => read_lock(map_lock)
while queue_lock could be (but isn't) taken in interrupt context.

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Acked-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 9 insertions, 6 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 00c768860818..3c6d4ee8921d 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -512,12 +512,13 @@ static void queue_io(struct mapped_device *md, struct bio *bio)
 struct dm_table *dm_get_table(struct mapped_device *md)
 {
         struct dm_table *t;
+        unsigned long flags;
 
-        read_lock(&md->map_lock);
+        read_lock_irqsave(&md->map_lock, flags);
         t = md->map;
         if (t)
                 dm_table_get(t);
-        read_unlock(&md->map_lock);
+        read_unlock_irqrestore(&md->map_lock, flags);
 
         return t;
 }
@@ -1910,6 +1911,7 @@ static int __bind(struct mapped_device *md, struct dm_table *t,
 {
         struct request_queue *q = md->queue;
         sector_t size;
+        unsigned long flags;
 
         size = dm_table_get_size(t);
 
@@ -1940,10 +1942,10 @@ static int __bind(struct mapped_device *md, struct dm_table *t,
 
         __bind_mempools(md, t);
 
-        write_lock(&md->map_lock);
+        write_lock_irqsave(&md->map_lock, flags);
         md->map = t;
         dm_table_set_restrictions(t, q, limits);
-        write_unlock(&md->map_lock);
+        write_unlock_irqrestore(&md->map_lock, flags);
 
         return 0;
 }
@@ -1951,14 +1953,15 @@ static int __bind(struct mapped_device *md, struct dm_table *t,
 static void __unbind(struct mapped_device *md)
 {
         struct dm_table *map = md->map;
+        unsigned long flags;
 
         if (!map)
                 return;
 
         dm_table_event_callback(map, NULL, NULL);
-        write_lock(&md->map_lock);
+        write_lock_irqsave(&md->map_lock, flags);
         md->map = NULL;
-        write_unlock(&md->map_lock);
+        write_unlock_irqrestore(&md->map_lock, flags);
         dm_table_destroy(map);
 }