> On Tue, Nov 01, 2022 at 11:11:37PM +0800, Jinlong Chen wrote:
> > Add a helper blk_mq_alloc_request_nocache() to alloc request without
> > cache. This makes blk_mq_alloc_request() more readable.
> >
> > Signed-off-by: Jinlong Chen <nickyc975@xxxxxxxxxx>
> > ---
> > block/blk-mq.c | 47 +++++++++++++++++++++++++++++------------------
> > 1 file changed, 29 insertions(+), 18 deletions(-)
> >
> > diff --git a/block/blk-mq.c b/block/blk-mq.c
> > index 87a6348a0d0a..2fae111a42c8 100644
> > --- a/block/blk-mq.c
> > +++ b/block/blk-mq.c
> > @@ -572,36 +572,47 @@ static struct request *blk_mq_alloc_cached_request(struct request_queue *q,
> > return rq;
> > }
> >
> > +static struct request *blk_mq_alloc_request_nocache(struct request_queue *q,
> > + blk_opf_t opf, blk_mq_req_flags_t flags)
>
> The name is a bit odd, but I can't think off a better one.
>
> > + struct blk_mq_alloc_data data = {
> > .q = q,
> > .flags = flags,
> > .cmd_flags = opf,
> > .nr_tags = 1,
> > };
>
> And this now has superflous indenation. Overall, while the separate
> helper looks marginally nicer, I'm not really sure it is worth the
> churn.
I'll drop the patch if you think it is not worth the churn. But I
started doing this because of the following goto statement:
rq = blk_mq_alloc_cached_request(q, opf, flags);
if (!rq) {
[...]
ret = blk_queue_enter(q, flags);
[...]
rq = __blk_mq_alloc_requests(&data);
if (!rq)
goto out_queue_exit;
}
[...]
out_queue_exit:
blk_queue_exit(q);
return ERR_PTR(-EWOULDBLOCK);
Queue entering has been moved into the fallback path, left queue exiting
outside. Should I just eliminate the goto statement and move the error
handling into the fallback path too? Like:
rq = blk_mq_alloc_cached_request(q, opf, flags);
if (!rq) {
[...]
ret = blk_queue_enter(q, flags);
[...]
rq = __blk_mq_alloc_requests(&data);
if (!rq) {
blk_queue_exit(q);
return ERR_PTR(-EWOULDBLOCK);
}
}
Thanks!
Jinlong Chen
