dm raid1: switch rh_in_sync to blocking in do_reads

The call to rh_in_sync() in do_reads() should be allowed to block.  It is in
the mirror worker thread which already permits blocking operations.  This will
be needed to support clustered mirroring which will perform network
operations.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/md/dm-raid1.c

@@ -741,7 +741,7 @@ static void do_reads(struct mirror_set *ms, struct bio_list *reads)
 		/*
 		 * We can only read balance if the region is in sync.
 		 */
-		if (rh_in_sync(&ms->rh, region, 0))
+		if (rh_in_sync(&ms->rh, region, 1))
 			m = choose_mirror(ms, bio->bi_sector);
 		else
 			m = ms->default_mirror;