tree 2e4c01da3f7cda8e5903dcc9e786e0bbc284261f
parent f45958756fef552436e4a63029a168495920026e
author Shaohua Li <shli@fb.com> 1490394047 -0700
committer Shaohua Li <shli@fb.com> 1490459886 -0700

md/raid1: skip data copy for behind io for discard request

discard request doesn't have data attached, so it's meaningless to
allocate memory and copy from original bio for behind IO. And the copy
is bogus because bio_copy_data_partial can't handle discard request.

We don't support writesame/writezeros request so far.

Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>