md/raid1: skip data copy for behind io for discard request
authorShaohua Li <shli@fb.com>
Fri, 24 Mar 2017 22:20:47 +0000 (15:20 -0700)
committerShaohua Li <shli@fb.com>
Sat, 25 Mar 2017 16:38:06 +0000 (09:38 -0700)
commit41743c1f046a14c6749fd1808bb3793c08e47a3e
tree2e4c01da3f7cda8e5903dcc9e786e0bbc284261f
parentf45958756fef552436e4a63029a168495920026e
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>
drivers/md/raid1.c