On 12/09/2014 11:27 AM, David Sterba wrote: >> > Today the lvm-snapshot and btrfs behave very poor: it is not >> > predictable which device is pick (the original or the snapshot). >> > These patch *avoid* most problems skipping the snapshots, which >> > to me seems a reasonable default. >> > For the other case the user is still able to mount any disks >> > [combination] passing them directly via command line ( >> > mount /dev/sdX -o device=/dev/sdY,device=/dev/sdz... );
> Beware that passing 'device' does not mean that btrfs will use that > device to assemble the filesystem. It only says to scan the device the > same way any preceding 'btrfs dev scan' would do. I thought a bit about your sentence, but I was unable to understand the difference. Could you describe a case where it is different ? I have quite clear that "btrfs scan <dev>" and "mount -o device=<dev>" do the same thing: these fill a table with the devices information grouped by fsid. Then the kernel uses this table as hint to pick the devices for a filesystem. So except some strange case (like device "hot" removed) this shouldn't make any difference... Or not ? The point is that when a btrfs scan is ran asynchronously, a snapshot "may" hide the origin volume. Where the word "may" means that it is not predictable. Passing the device solve only this point: it becomes predictable which device is used. -- gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it> Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
