From mboxrd@z Thu Jan 1 00:00:00 1970 From: crquan@gmail.com Subject: [PATCH 0/3] dm-target: target_type improvements Date: Fri, 19 Dec 2008 12:19:42 +0800 Message-ID: <1229660385-17153-1-git-send-email-crquan@gmail.com> Return-path: Sender: linux-kernel-owner@vger.kernel.org To: dm-devel@redhat.com Cc: Alasdair G Kergon , linux-kernel@vger.kernel.org List-Id: dm-devel.ids From: Cheng Renquan The series of patches: 1. use module's refcount instead of self-maintained use field; 2. use pointer reference instead of making a copy of target_type; 3. totally remove tt_internal; The 3rd patch may be controversial, On Wed, Dec 17, 2008 at 7:48 PM, Alasdair G Kergon wrote: > Target registrations should be rare one-off events. The existing trade-off > is > in favour of a cleaner interface (that does not expose private fields). The > struct target_type passed to dm_register_target is always static read-only > data > and perhaps that could be enforced and a pointer stored in tt_internal > instead > of making a copy. But I still think it's worth it: 1. current users of struct target_type hasn't been marked with const, just static; 2. other similar structures (file_system_type in filesystems, packet_type in net core, ) all have internally used list_head for manage purpose; this design can avoid memory frag from kmalloc/kfree. -- Cheng Renquan, Shenzhen, China