Quoting Vitaliy Gusev (vgusev@xxxxxxxxxx): > On 12 December 2007 20:31:15 Serge E. Hallyn wrote: > > Quoting Vitaliy Gusev (vgusev@xxxxxxxxxx): > > > Hello > > > > > > On 6 December 2007 18:51:30 Serge E. Hallyn wrote: > > > > > fl_pid is used by nfs, fuse and gfs2. For instance nfs keeps in > > > > > fl_pid some unique id to identify locking process between hosts - it > > > > > is not a process pid. > > > > > > > > Ok, but so the struct user_flock->fl_pid is being set to the task's > > > > virtual pid, while the struct kernel_flock->fl_pid is being set to > > > > task->tgid for nfsd use. > > > > > > > > Why can't nfs just generate a uniqueid from the struct pid when it > > > > needs it? > > > > > > I think it is hard. lockd uses struct nlm_host to get process unique id > > > (see __nlm_alloc_pid() function). > > > > Looks pretty simple though... That whole set of code could even stay > > the same except for in __nlm_alloc_pid(): > > > > option 1: compare struct pid* instead of uint32_t pid > > option 2: use the "global pid" out of the stored struct pid, > > something like pid->numbers[0].nr. > > We can't use process pid. Process pid is circulated! NFS (lockd) needs > unique process id between hosts which can't repeat oneself. Ok sorry - by letting this thread sit a few days I lost track of where we were. I see now, so you're saying fl_pid for nfs is not in fact a task pid. It's a magically derived unique id. (And you say it is unique across all the nfs clients?) So does the p in fl_pid stand for something, or could we rename it to fl_id or fl_uniqueid? Maybe that's too much bother, but so long as we're bothering with a pid cleanup at all it seems worth it to me. On the other hand maybe J. Bruce Fields was right and we should accept the fact that the flock->fl_pid shouldn't be taken too seriously, and leave it be. -serge > > > > Fuse just seems to copy the pid to report it to userspace, so it would > > > > just copy pid_vnr(kernel_flock->pid) into user_flock->fl_pid. > > > > > > > > Anyway I haven't looked at all the uses of struct fl_pid, but you > > > > can always get the pidnr back from the struct pid if needed so there > > > > should be no problem. > > > > > > > > The split definately seems worthwhile to me, so that > > > > user_flock->fl_pidnr can always be said to be the pid in the acting > > > > process' namespace, and flock->fl_pid can always be a struct pid, > > > > rather than having fl_pid sometimes be current->tgid, or sometimes > > > > pid_vnr(flock->fl_nspid)... > > > > > > > > -serge > > > > - > > > > To unsubscribe from this list: send the line "unsubscribe > > > > linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx > > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > > -- > > > Thank, > > > Vitaliy Gusev > > > > - > > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > -- > Thank, > Vitaliy Gusev - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
