CHROMIUM: verity: add BUG in check_block for consistency with verify_path

CHROMIUM: verity: add BUG in check_block for consistency with verify_path

We assume that the caller guarantees that all nodes along the path are
already populated. We already have a BUG_ON checking this in verify_path.
This change adds a similar BUG_ON in check_path and removes the code
which checks the entry state.

BUG=9752
TEST=Ran unit tests in dm-verity.git. Ran platform_DMVerityCorruption on H/W.

Change-Id: Id456d9e495978c93d0be28bd895e5ced28d9973b
Signed-off-by: Mandeep Singh Baines <msb@chromium.org>;

Committed: http://chrome-svn/viewvc/chromeos?view=rev&revision=90287c8

[Will Drewry, 2011-02-11 19:30:55]

LGTM

I'm not a fan of crashing the kernel on I/O error or other issue that is
detectable, but at least it's consistent.  Once the refactor is done, we need to
go back through and clean up all the error paths to ensure that we can provide
platform-specific handling to avoid nasty repeat BUG()s.

[Mandeep Singh Baines, 2011-02-11 21:20:41]

wad@chromium.org (wad@chromium.org) wrote:
> LGTM
> 
> I'm not a fan of crashing the kernel on I/O error or other issue that is
> detectable, but at least it's consistent.  Once the refactor is

We are making this part of the contract. So if this BUG is ever hit,
it is because of a real bug in the caller. The caller must guarantee
that all I/O is complete before calling dm_bht(); verity makes
this guarantee.

> done, we need to
> go back through and clean up all the error paths to ensure that we
> can provide
> platform-specific handling to avoid nasty repeat BUG()s.
> 
> http://codereview.chromium.org/6246094/