On 4/5/07, Srivatsa Vaddagiri <[EMAIL PROTECTED]> wrote: > > If the container directory were to have no refcount on the nsproxy, so > > the initial refcount was 0, > > No it should be 1. > > mkdir H1/foo > rcfs_create() > ns = dup_namespaces(parent); > > .... > dentry->d_fsdata = ns; > > ns should have a refcount of 1 to begin with.
Right - that's my point, you're effectively passing the initial refcount of the nsproxy to the container directory's d_fsdata reference. > > - refcount of a nsproxy attached to a directory dentry can never > fall to zero because of tasks coming in and out. The only > way for the refcount of such nsproxies to fall to zero and > hence trigger their destruction is thr' the rmdir i/f. > > - New nsproxies derived from the base directory nsproxy > can have their's refcount go to zero as tasks exit or move > around and hence they will be destroyed. > > Does that sound like correct behavior? Sounds good. > > > Possibly - there are two choices: > > > > 1) expose a refcount to them directly, and just interrogate the > > refcount from the generic code to see if it's safe to delete the > > directory > > > > 2) have a can_destroy() callback with well defined semantics about > > when it's safe to take refcounts again - it's quite possible that one > > subsystem can return true from can_destroy() but others don't, in > > which case the subsystem can become active again. > > Lets go back to the f_bc example here for a moment. Lets say T1 was in C1 and > opened file f1. f1->f_bc points to C1->beancounter. > > T1 moves from C1 -> C2, but f1 is not migrated. > C1->beancounter.count stays at 1 (to account for f1->f_bc). > > File f1 is closed. C1->beancounter.count becomes zero. > > Now user issues rmdir C1. If rmdir finds (after taking manage_mutex that > is) > > - zero tasks in C1 > - zero refcount in C1->beancounter > > why is it not safe to assume that C1->beancounter.count will continue to > stay zero? > > Basically I am struggling to answer "How can a zero refcount (beancounter) > object go non-zero when zero tasks are attached to it" .. In that case, I think you're fine. Your last posted patches didn't provide a way to check for that, though, as far as I could see. Paul ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ ckrm-tech mailing list https://lists.sourceforge.net/lists/listinfo/ckrm-tech
