Kent Overstreet <kmo@xxxxxxxxxxxxx> writes: > On Thu, Nov 13, 2014 at 02:52:02PM +0100, Mathijs Kwik wrote: >> The kernel documentation on suspend is VERY clear you should NOT touch >> anything on disk between suspend and resume. So activating luks and LVM >> is probably risky already, but it apppears both luks and LVM do not make >> any on-disk changes when activated and any in-memory state (within the >> resumed image) is still valid. The benefit of activating luks and LVM >> before resume seems to be that it allows resuming from encrypted/lvm >> volumes. > > Yeah, this is handled for in kernel stuff with the freezing mechanism, which > bcache uses. > >> > > So, userspace shouldn't have to do anything to tell bcache about > hibernation. I understand bcache knows when the system hibernates so it can do some bookkeeping/flushing. What I don't get, is how this will protect the system in the short phase before resume, when my initrd activates bcache and lvm, _before_ it checks for a resume image. I guess bcache will just start running as usual. Maybe flushing some dirty buckets, cache some new stuff (when lvm searches for volumes and udev reads labels & more). Then finally the resume mechanism loads the old hibernated system, while the cache has changed in the mean time! Won't this cause issues? > > The dev branch is getting a true read only mode (still in progress), but this > isn't relevant to hibernation. > > bcache kernel threads (allocator thread, gc thread) should be correct w.r.t. > hibernation, but - maybe the workqueue usage isn't. > > I'm probably not going to be able to get to this in the next couple days, but > this is a pretty serious issue. Can you ping me again every couple days until I > get a fix out for this, and myabe file a bug somewhere? (i think > bugzilla.kernel.org has been used for bcache bugs before...) I will file a report once I'm sure what the exact cause for my data-loss was. If I understand you correctly, all should be safe and well, no matter what (initramfs) userspace does in between and the only thing that might not be safe is the workqueue? -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
