ceph: fix possible integer overflow in ceph_zero_objects()

In 'ceph_zero_objects', promote 'object_size' to 'u64' to avoid possible
integer overflow.

Compile tested only.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Dmitry Kandybka <d.kandybka@gmail.com>
Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

Author: dmikand

fs/ceph/file.c

@@ -2616,7 +2616,7 @@ static int ceph_zero_objects(struct inode *inode, loff_t offset, loff_t length)
 	s32 stripe_unit = ci->i_layout.stripe_unit;
 	s32 stripe_count = ci->i_layout.stripe_count;
 	s32 object_size = ci->i_layout.object_size;
-	u64 object_set_size = object_size * stripe_count;
+	u64 object_set_size = (u64) object_size * stripe_count;
 	u64 nearly, t;
 
 	/* round offset up to next period boundary */