Am Freitag, 27. April 2007 08:18 schrieb Pekka J Enberg: > > No. The snapshot is just that. A snapshot in time. From kernel point of > > view, it doesn't matter one bit what when you did it or if the state has > > changed before you resume. It's up to userspace to make sure the user > > doesn't do real work while the snapshot is being written to disk and > > machine is shut down.
On Fri, 27 Apr 2007, Oliver Neukum wrote: > And where is the benefit in that? How is such user space freezing logic > simpler than having the kernel do the write? > > What can you do in user space if all filesystems are r/o that is worth the > hassle? I am talking about snapshot_system() here. It's not given that the filesystems need to be read-only (you can snapshot them too). The benefit here is that you can do whatever you want with the snapshot (encrypt, compress, send over the network) and have a clean well-defined interface in the kernel. In addition, aborting the snapshot is simpler, simply munmap() the snapshot. The problem with writing in the kernel is obvious: we need to add new code to the kernel for compression, encryption, and userspace interaction (graphical progress bar) that are important for user experience. Pekka - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/