problems writing to USB storage was Re: cannot upload to MTP phone

[David Lang]

slightly hijacking the thread here, because I think the problem is larger than 
just MTP.

I've run into similar problems in the last week trying to write a SD card for a 
raspberry pi.

I can mount cards and read them (both with a USB adapter as /dev/sdb and with 
the intenal adapter as /dev/mm*), but I can't write to them.

If I try to write to the internal adapter I get lots of async page write 
failures, if I write to external adapters/thumb drives it claims to work, and 
finishes very quickly, but the data does not get to disk (it claims to have 
written, but it only gets to the system buffers. doing a sync before ejecting 
doesn't help)

This is running as root, both trying to mount and then touch a file and also 
doing a dd to the raw device.

It's been several months since the last time I needed to do this, so I don't 
know when it broke.

David Lang