md/raid1 - don't assume newly allocated bvecs are initialised.

Since commit d3f761104b
newly allocated bvecs aren't initialised to NULL, so we have
to be more careful about freeing a bio which only managed
to get a few pages allocated to it.  Otherwise the resync
process crashes.

This patch is appropriate for 2.6.29-stable.

Cc: stable@kernel.org
Cc: "Jens Axboe" <jens.axboe@oracle.com>
Reported-by: Gabriele Tozzi <gabriele@tozzi.eu>
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/raid1.c

@@ -123,6 +123,7 @@ static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
 				goto out_free_pages;
 
 			bio->bi_io_vec[i].bv_page = page;
+			bio->bi_vcnt = i+1;
 		}
 	}
 	/* If not user-requests, copy the page pointers to all bios */
@@ -138,9 +139,9 @@ static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
 	return r1_bio;
 
 out_free_pages:
-	for (i=0; i < RESYNC_PAGES ; i++)
 	for (j=0 ; j < pi->raid_disks; j++)
-			safe_put_page(r1_bio->bios[j]->bi_io_vec[i].bv_page);
+		for (i=0; i < r1_bio->bios[j]->bi_vcnt ; i++)
+			put_page(r1_bio->bios[j]->bi_io_vec[i].bv_page);
 	j = -1;
 out_free_bio:
 	while ( ++j < pi->raid_disks )