should ext2fs_get_device_size() be returning EFBIG for >8T (or 16T?)

I have a bug saying hey, I can't grow my filesystem on a 16T device, and it's because really we can only go to (2^32)-1 blocks, not (2^32)...

I was going to just silently round down by a block, because for example LVM makes it *very* easy to make exactly 16T devices; dropping a block at mkfs/growfs time seems reasonable to me.

So that led me to ext2fs_get_device_size, and I see it actually has the maximum allowable filesystem size encoded in it, and you get EFBIG if it's bigger.

I think this disallows you from being able to specify a smaller size on the resize cmdline too; the device size check bails out before that.

I'm not sure what the plan is for size checks in the ext4 world, but it seems to me that the device size check and the acceptable fs size checks should be separate things.

Comments?

Thanks,
-Eric

Actually I guess it's looking at the largest number a blk_t can hold, but I think the same principle applies. Maybe it's not a big deal today...

-Eric