[libmultipath] blacklist exceptions issues
the current situation is fishy. Ben pointed a true braino in the
code I introduced when restructuring the blacklist lib :
in _filter_path(), I test each _filter_*() for r!=0 , where I intented
to check for r>0.
r==0 implements : "exit on first blacklist or exception match".
r>0 implements : "exit on first blacklist match".
With this later behaviour I can set things like that for max safety and
efficiency :
blacklist {
devnode .*
device {
vendor .*
product .*
}
wwid .*
}
blacklist_exceptions {
devnode sd.*
device {
vendor IET.*
product .*
}
wwid "
1646561646265.*"
}
or pragmatically :
blacklist {
devnode .*
wwid .*
}
blacklist_exceptions {
devnode sd.*
wwid "
1646561646265.*"
}
Working that out, I also realized there may be another small
misbehaviour :
First, a little background on path discovery operations :
1) /sys/block parsing shows devnode names
2) devnode names examination shows device identification strings
3) these strings help us choose a getuid helper, which finally shows
wwids
Meaning we want the devnode blacklisting to prevail over device and
wwid, in case we know we don't have device strings available (loop, dm-,
raw, ...)
Similarily, we want the device blacklist to prevail over wwid, in case
we know we don't have getuid callout available. I have no example for
this case though, so it shouldn't be as important as the previous one.
Problem is we challenge _filter_device() after _filter_wwid().
This can be easily shufled around.