[PATCH] device-mapper: Export map_info

Export map_info (part of bio->bi_private) for targets like multipath to use
for storing context.
Signed-Off-By: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/dm.c

@@ -43,6 +43,13 @@ struct target_io {
 	union map_info info;
 };
 
+union map_info *dm_get_mapinfo(struct bio *bio)
+{
+        if (bio && bio->bi_private)
+                return &((struct target_io *)bio->bi_private)->info;
+        return NULL;
+}
+
 /*
  * Bits for the md->flags field.
  */
@@ -1172,6 +1179,8 @@ static struct block_device_operations dm_blk_dops = {
 	.owner = THIS_MODULE
 };
 
+EXPORT_SYMBOL(dm_get_mapinfo);
+
 /*
  * module hooks
  */

drivers/md/dm.h

@@ -190,5 +190,6 @@ int dm_stripe_init(void);
 void dm_stripe_exit(void);
 
 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
+union map_info *dm_get_mapinfo(struct bio *bio);
 
 #endif