Help! - fuse and loopback - not working together

[Greg Freemyer]

All,

I don't know if this is a kernel issue or not.  I just don't know
where else to look for help.

I seem to be having a conflict between fuse and loopback devices.  I
can get each to work fine independently, but I can get them to work
together.  This has worked with older kernels, but I can't get it to
work with a 3.16.6 kernel.

I'm just guessing the issue is a kernel issue.  I really don't want to
have to compile kernels to track this down, but it may come to that.

All userspace tools I'm using are opensource, so I dod have the
userspace source to work with, although I'm not the author.

=====
I'm trying to use a tool (ewfmount) that leverages the fuse kernel
sub-system to merge several files together and also uncompress them.

Thus I might originally have:

image.E01
image.E02
image.E03

where each of those files is a segment of full dd image that has been
compressed.

If I run "ewfmount image.E01 /mnt" then a virtual file /mnt/ewf1 is
created.  That is working fine.

In the past I have been able to now loopback mount partitions from
that virtual file via:

mount -t hfsplus -r -o loop,offset=209735680 /mnt/ewf1 /mnt

Currently that is failing with:
mount: /mnt/ewf1: failed to setup loop device: Permission denied

Thus loop back seems broken.  To test that I copied the virtual file
to a real file via dd.  After that mount properly accesses the true
file.

===
Thus:

 fuse is working right to merge my files together and uncompress them.

loopback is working right when the object being mounted is a standard file.

loopback is failing when pointed at the virtual file created by fuse.
===

I am suspicious of the kernel because this has worked for me in the
pastk but with older kernels.  I can't say when it last worked, but at
least a year ago.

Any suggestions / help appreciated.

Thanks
Greg
--
Greg Freemyer