> > 2. this logic kill multi thread application. > > > > this logic mean mmap_sem grabbing until unfreeze. > > it mean othrer thread in the same process can't page-fault although > > it don't touch frozen-sb. > > it seems strange. > > Hm, I hadn't thought about this ... On the one hand, ->page_mkwrite can > already sleep, though a userspace freeze/unfreeze could potentially take > much much longer. freeze/unfreeze *should* happen very quickly, but > nothing enforces that. > > Do you have any suggestions? One more comment. I read ioctl_fsfreeze() and freeze_bdev(), it call __fsync_super(). Oh, I don't think __fsync_suepr is very quick. So, page-fault have one unique characteristics. if page-fault return 0 without pte change, page-fault is occur again soon. then, if you need long time waiting, I think you can use following technique. unlock mmap_sem wait long-time lock mmap_sem goto out; it cause page-fault counter increment twice unintesionally. but no problem. fs-freeze is not freqently event. Am I missing anything? -- 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
