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    SubjectRe: [PATCH 6/7] md/raid10, LLVM: get rid of variable length array
    On Thu, Mar 16, 2017 at 05:15:19PM -0700, Michael Davidson wrote:
    > Replace a variable length array in a struct by allocating
    > the memory for the entire struct in a char array on the stack.
    >
    > Signed-off-by: Michael Davidson <md@google.com>
    > ---
    > drivers/md/raid10.c | 9 ++++-----
    > 1 file changed, 4 insertions(+), 5 deletions(-)
    >
    > diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
    > index 063c43d83b72..158ebdff782c 100644
    > --- a/drivers/md/raid10.c
    > +++ b/drivers/md/raid10.c
    > @@ -4654,11 +4654,10 @@ static int handle_reshape_read_error(struct mddev *mddev,
    > /* Use sync reads to get the blocks from somewhere else */
    > int sectors = r10_bio->sectors;
    > struct r10conf *conf = mddev->private;
    > - struct {
    > - struct r10bio r10_bio;
    > - struct r10dev devs[conf->copies];
    > - } on_stack;
    > - struct r10bio *r10b = &on_stack.r10_bio;
    > + char on_stack_r10_bio[sizeof(struct r10bio) +
    > + conf->copies * sizeof(struct r10dev)]
    > + __aligned(__alignof__(struct r10bio));
    > + struct r10bio *r10b = (struct r10bio *)on_stack_r10_bio;
    > int slot = 0;
    > int idx = 0;
    > struct bio_vec *bvec = r10_bio->master_bio->bi_io_vec;


    That's disgusting. Why not fix LLVM to support this?

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