I encountered this problem recently, and was able to solve it. Since there doesn’t seem to be a clear answer here, I thought I would attempt to fix that.
First off, it is important to understand that you can have put a filesystem directly on a block device. In that case, you would mount/fsck/etc the device, like:
/dev/sda
NOT /dev/sda1
To be clear, this means you can have a filesystem without a partition table. This is called a partionless filesystem, and has been around for a long time. Here is a thread on stackexchange debating the merits:
https://unix.stackexchange.com/questions/14010/the-merits-of-a-partitionless-filesystem
Next, this seems to be a somewhat common problem, mostly because Ubuntu decided to include the option of installing directly to a device.
The problem arises because in some cases a partitionless install breaks the formula EXT4 uses to compute disk size. You can tell if you have this problem if the difference between the expected and actual size is 265 bytes. (and no that’s not supposed to be 256) Google just told me that 265 is the size of an EXT4 inode structure. Since putting filesystems on bare devices is supported, and in some cases even encouraged, I would assume this is a bug. I was using kernel version 2.6.39 when it happened to me.
Finally, the solution. It’s quite easy really.
First, you need to force an fsck of the filesystem:
fsck.ext4 -f /dev/(your device)
Again, for a partionless device you would use for instance /dev/sda, not /dev/sda1 or anything like that.
Next you need to resize the device to match what ext4 wants:
resize2fs /dev/(your device) ####
Where <####> is the value from the error message:
EXT4-fs (sda): bad geometry: block count exceeds size of device (#### blocks)
PLEASE NOTE: the usual disclaimers apply. Messing with filesystems is dangerous etc. Be careful! This is meant is a last-ditch attempt to fix a filesystem, when the only other alternative is to reformat. I am not a filesystem expert, and have no idea if the above fix will work on your system, or introduce problems later on down the road. YMMV.
Once you’ve rescued your data, the safest approach is probably to reformat and create a standard partition table, if you can.
Best Answer
Assuming that the problem isn't actually related to accessing large files in general (which you are suggesting in a comment above) you might want to try ImDisk. ImDisk is a small and lightweight utility for mounting disk images, including CD/DVD as well as HDD images. It might have better luck mounting the image than Windows' own mounting tool.