On Thu, 08/01 14:28, Stefan Hajnoczi wrote: > On Wed, Jul 31, 2013 at 06:13:53PM +0800, Fam Zheng wrote: > > BlockDriverState lifecycle management is needed by future features such as > > image fleecing and blockdev-add. This series adds reference count to > > BlockDriverState. > > > > The first two patches clean up two odd BlockDriverState use cases, so all > > code > > uses bdrv_new() to create BlockDriverState instance. > > > > Then implemented bdrv_ref() and bdrv_unref() to operate on refcnt: > > Initially, > > refcnt is 1, which means bdrv_unref is effectively a bdrv_delete() here. So > > patch 04 has a search and replace to convert bdrv_delete to bdrv_unref, > > before > > bdrv_ref is used anywhere. 05~08 patches calls bdrv_ref for device attach, > > block-migration and nbd. > > > > The rule is: Either bdrv_ref() or bdrv_new() must have a matching > > bdrv_unref() call, and the last matching bdrv_unref deletes the bs. > > > > v3: > > 03: Removed unnecessary bdrv_close() call. > > > > v2: > > 05: Removed: "block: use BlockDriverState refcnt for device > > attach/detach" > > 07: Fix xen_disk blk_disconnect() as it depended on device attach > > refcnt. > > > > Fam Zheng (7): > > vvfat: use bdrv_new() to allocate BlockDriverState > > iscsi: use bdrv_new() instead of stack structure > > block: implement reference count for BlockDriverState > > block: make bdrv_delete() static > > migration: omit drive ref as we have bdrv_ref now > > xen_disk: simplify blk_disconnect with refcnt > > nbd: use BlockDriverState refcnt > > Follow-up question: > > Did you look at using bdrv_ref() for the BDS <- BlockJob relationship > too? > > blockdev.c block job code still uses the DriveInfo refcount after your > series. The BDS reference would be sufficient since the DriveInfo > fields are not used by block jobs. > For now they coexist, which works but with redundancy. I will send follow-up patch(es) to clean up block job to only use BDS refcount.
-- Fam
