Re: [RFC PATCH v1 21/57] sunrpc: Remove PAGE_SIZE compile-time constant assumption

Chuck Lever
2024-10-16T15:00:28Z

On Wed, Oct 16, 2024 at 03:42:12PM +0100, Ryan Roberts wrote:
> + Chuck Lever, Jeff Layton
>
> This was a rather tricky series to get the recipients correct for and my script
> did not realize that "supporter" was a pseudonym for "maintainer" so you were
> missed off the original post. Appologies!
>
> More context in cover letter:
> https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@arm.com/
>
>
> On 14/10/2024 11:58, Ryan Roberts wrote:
> > To prepare for supporting boot-time page size selection, refactor code
> > to remove assumptions about PAGE_SIZE being compile-time constant. Code
> > intended to be equivalent when compile-time page size is active.
> >
> > Updated array sizes in various structs to contain enough entries for the
> > smallest supported page size.
> >
> > Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
> > ---
> >
> > ***NOTE***
> > Any confused maintainers may want to read the cover note here for context:
> > https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@arm.com/
> >
> > include/linux/sunrpc/svc.h | 8 +++++---
> > include/linux/sunrpc/svc_rdma.h | 4 ++--
> > include/linux/sunrpc/svcsock.h | 2 +-
> > 3 files changed, 8 insertions(+), 6 deletions(-)
> >
> > diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
> > index a7d0406b9ef59..dda44018b8f36 100644
> > --- a/include/linux/sunrpc/svc.h
> > +++ b/include/linux/sunrpc/svc.h
> > @@ -160,6 +160,8 @@ extern u32 svc_max_payload(const struct svc_rqst *rqstp);
> > */
> > #define RPCSVC_MAXPAGES ((RPCSVC_MAXPAYLOAD+PAGE_SIZE-1)/PAGE_SIZE \
> > + 2 + 1)
> > +#define RPCSVC_MAXPAGES_MAX ((RPCSVC_MAXPAYLOAD+PAGE_SIZE_MIN-1)/PAGE_SIZE_MIN \
> > + + 2 + 1)

There is already a "MAX" in the name, so adding this new macro seems
superfluous to me. Can we get away with simply updating the
"RPCSVC_MAXPAGES" macro, instead of adding this new one?

> > /*
> > * The context of a single thread, including the request currently being
> > @@ -190,14 +192,14 @@ struct svc_rqst {
> > struct xdr_stream rq_res_stream;
> > struct page *rq_scratch_page;
> > struct xdr_buf rq_res;
> > - struct page *rq_pages[RPCSVC_MAXPAGES + 1];
> > + struct page *rq_pages[RPCSVC_MAXPAGES_MAX + 1];
> > struct page * *rq_respages; /* points into rq_pages */
> > struct page * *rq_next_page; /* next reply page to use */
> > struct page * *rq_page_end; /* one past the last page */
> >
> > struct folio_batch rq_fbatch;
> > - struct kvec rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */
> > - struct bio_vec rq_bvec[RPCSVC_MAXPAGES];
> > + struct kvec rq_vec[RPCSVC_MAXPAGES_MAX]; /* generally useful.. */
> > + struct bio_vec rq_bvec[RPCSVC_MAXPAGES_MAX];
> >
> > __be32 rq_xid; /* transmission id */
> > u32 rq_prog; /* program number */
> > diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
> > index d33bab33099ab..7c6441e8d6f7a 100644
> > --- a/include/linux/sunrpc/svc_rdma.h
> > +++ b/include/linux/sunrpc/svc_rdma.h
> > @@ -200,7 +200,7 @@ struct svc_rdma_recv_ctxt {
> > struct svc_rdma_pcl rc_reply_pcl;
> >
> > unsigned int rc_page_count;
> > - struct page *rc_pages[RPCSVC_MAXPAGES];
> > + struct page *rc_pages[RPCSVC_MAXPAGES_MAX];
> > };
> >
> > /*
> > @@ -242,7 +242,7 @@ struct svc_rdma_send_ctxt {
> > void *sc_xprt_buf;
> > int sc_page_count;
> > int sc_cur_sge_no;
> > - struct page *sc_pages[RPCSVC_MAXPAGES];
> > + struct page *sc_pages[RPCSVC_MAXPAGES_MAX];
> > struct ib_sge sc_sges[];
> > };
> >
> > diff --git a/include/linux/sunrpc/svcsock.h b/include/linux/sunrpc/svcsock.h
> > index 7c78ec6356b92..6c6bcc82685a3 100644
> > --- a/include/linux/sunrpc/svcsock.h
> > +++ b/include/linux/sunrpc/svcsock.h
> > @@ -40,7 +40,7 @@ struct svc_sock {
> >
> > struct completion sk_handshake_done;
> >
> > - struct page * sk_pages[RPCSVC_MAXPAGES]; /* received data */
> > + struct page * sk_pages[RPCSVC_MAXPAGES_MAX]; /* received data */
> > };
> >
> > static inline u32 svc_sock_reclen(struct svc_sock *svsk)
>

--
Chuck Lever