04 сент. 2015 г. 12:57 пользователь "Hitoshi Mitake" < mitake.hito...@gmail.com> написал: > > On Fri, Sep 4, 2015 at 5:51 PM, Hitoshi Mitake <mitake.hito...@gmail.com> wrote: > > On Wed, Sep 2, 2015 at 9:36 PM, Vasiliy Tolstov <v.tols...@selfip.ru> wrote: > >> 2015-09-01 6:03 GMT+03:00 Hitoshi Mitake <mitake.hito...@lab.ntt.co.jp >: > >>> This patch refines discard support of the sheepdog driver. The > >>> existing discard mechanism was implemented on SD_OP_DISCARD_OBJ, which > >>> was introduced before fine grained reference counting on newer > >>> sheepdog. It doesn't care about relations of snapshots and clones and > >>> discards objects unconditionally. > >>> > >>> With this patch, the driver just updates an inode object for updating > >>> reference. Removing the object is done in sheep process side. > >>> > >>> Cc: Teruaki Ishizaki <ishizaki.teru...@lab.ntt.co.jp> > >>> Cc: Vasiliy Tolstov <v.tols...@selfip.ru> > >>> Cc: Jeff Cody <jc...@redhat.com> > >>> Signed-off-by: Hitoshi Mitake <mitake.hito...@lab.ntt.co.jp> > >> > >> > >> I'm test this patch and now discard working properly and no errors in > >> sheepdog log file. > >> > >> Tested-by: Vasiliy Tolstov <v.tols...@selfip.ru> > > > > On the second thought, this patch has a problem of handling snapshot. > > Please drop this one (1st patch is ok to apply). > > > > I'll solve the problem in sheepdog side. > > On the third thought, this patch can work well ;) Please pick this patch, Jeff. > > I considered about a case of interleaving of snapshotting and > discarding requests like below: > 1. user invokes dog vdi snapshot, a command for making current VDI > snapshot (updating inode objects) > 2. discard request from VM before the request of 1 completes > 3. discard completes > 4. request of 1 completes > > In this case, some data_vdi_id of original inode can be overwritten > before completion of snapshotting. However, this behavior is valid > because dog vdi snapshot doesn't return ack to the user. >
This is normal for snapshots, to get consistent data you need to cooperate with guest system to get freeze it fs before snapshot. Quemu-ga already have this via sending freeze to fs beforw and thaw after snapshot . > Thanks, > Hitoshi > > > > > Thanks, > > Hitoshi > > > >> > >> -- > >> Vasiliy Tolstov, > >> e-mail: v.tols...@selfip.ru > >> -- > >> sheepdog mailing list > >> sheep...@lists.wpkg.org > >> https://lists.wpkg.org/mailman/listinfo/sheepdog