[RFC][PATCH 0/2] xfstests on ubifs

[Eric Biggers <ebiggers3@gmail.com>]

From: Eric Biggers <ebiggers@google.com>

Hello,

Since ubifs encryption has been merged into the 4.10 kernel, I wanted to run my
new encryption tests on ubifs to make sure it's compatible with ext4 and f2fs.
xfstests doesn't support ubifs yet but I was able to hack something together.
I'm sending my patches for anyone who may be interested.

The first patch adds ubifs support to xfstests itself.  This is a fairly small
patch that just deals with a couple quirks of ubifs, e.g. requiring a char
device rather than a block device.

The second patch updates xfstests-bld (a separate project maintained by Theodore
Ts'o) to support ubifs with kvm-xfstests and gce-xfstests.  It uses block2mtd to
emulate MTD devices using standard block devices, then layers UBI volumes on top
of these.  Of course, actually running the tests is dependent on the xfstests
patch.

Note: I'm *not* an ubifs developer, and so far I haven't done much else besides
run the encryption tests.  There seemed to be a lot of failures when I tried
running some of the other generic xfstests, and also a strange failure in the
encryption test generic/402 that I wasn't able to fix; so if I haven't obviously
screwed something up, I strongly suggest the ubifs developers look into this.

Note 2: since mkfs.ubifs doesn't support creating encryption-capable filesystems
yet (ubifs v5), to get the encryption tests to work I also had to hack
_scratch_mkfs_encrypted() to use ubirmvol/ubimkvol instead of mkfs.  I assume
that the ubifs developers are planning to update mkfs.ubifs.

Eric