[dm-devel] bio's bi_size bug also be founded at dm-stripe.c and dm-snap.c

[Zhao Qian]

As i had written here before, sometimes bio which dispatched to the dm's target, it's bi_size could exceed
region size in dm-mirror.c, i also found similar problem in dm-stripe.c and dm-snap.c , in such situation,
bio's bi_size could exceed strip target's chunk size and snap target's chunk size, but in current code, we
never care about this. so in strip target we could read/write bad position after stripe_map() function,
and cause same effect in dm-snap.c.
I think such bugs are very dangerous then kernel panic or cracsh becasue it may destroy your data 
in silence. we'd better to annonuce our linux users don't use thus dm-targets before we correct it.

Sincerely,
                Zhao Qian <zhaoqian at aaastor.com>