find_level_by_delta(): fix

Use resolved path (delta_r) when comparing file names.

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
ploop_replace_image(): fix message about bad level

The thing is, di->nimages can be higher than top_level due to snapshots,
so even if level is less than it, it can still be invalid. Therefore,
here we do only a basic sanity check, the proper check (against
top_level) is to be done later. Because of that we shouldn't tell
anything about upper level limit in the error message.

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
ploop_check(): add CHECK_IGNORE_INUSE flag

This is needed for ploop_replace_image() which checks the new delta
file. It's usually an exact copy of the delta file being used, so
DiskInUse flag is set for it. We need to check everything else
except for this flag.

Signed-off-by: Kir Kolyshkin <kir@openvz.org>