[PATCH v3 00/11] Allocate payload arrays dynamically

[cel@kernel.org]

From: Chuck Lever <chuck.lever@oracle.com>

In order to make RPCSVC_MAXPAYLOAD larger (or variable in size), we
need to do something clever with the payload arrays embedded in
struct svc_rqst and elsewhere.

My preference is to keep these arrays allocated all the time because
allocating them on demand increases the risk of a memory allocation
failure during a large I/O. This is a quick-and-dirty approach that
might be replaced once NFSD is converted to use large folios.

The downside of this design choice is that it pins a few pages per
NFSD thread (and that's the current situation already). But note
that because RPCSVC_MAXPAGES is 259, each array is just over a page
in size, making the allocation waste quite a bit of memory beyond
the end of the array due to power-of-2 allocator round up. This gets
worse as the MAXPAGES value is doubled or quadrupled.

This series also addresses similar issues in the socket and RDMA
transports.

Changes since v2:
* Address Jeff's review comments
* Address Neil's review comments
* Start removing a few uses of NFSSVC_MAXBLKSIZE

Chuck Lever (11):
  sunrpc: Remove backchannel check in svc_init_buffer()
  sunrpc: Add a helper to derive maxpages from sv_max_mesg
  sunrpc: Replace the rq_pages array with dynamically-allocated memory
  sunrpc: Replace the rq_vec array with dynamically-allocated memory
  sunrpc: Replace the rq_bvec array with dynamically-allocated memory
  sunrpc: Adjust size of socket's receive page array dynamically
  svcrdma: Adjust the number of RDMA contexts per transport
  svcrdma: Adjust the number of entries in svc_rdma_recv_ctxt::rc_pages
  svcrdma: Adjust the number of entries in svc_rdma_send_ctxt::sc_pages
  sunrpc: Remove the RPCSVC_MAXPAGES macro
  NFSD: Remove NFSSVC_MAXBLKSIZE from .pc_xdrressize

 fs/nfsd/nfs3proc.c                       |  4 +-
 fs/nfsd/nfsproc.c                        |  4 +-
 fs/nfsd/vfs.c                            |  2 +-
 include/linux/sunrpc/svc.h               | 31 +++++++++-----
 include/linux/sunrpc/svc_rdma.h          |  6 ++-
 include/linux/sunrpc/svcsock.h           |  4 +-
 net/sunrpc/svc.c                         | 51 +++++++++++++++---------
 net/sunrpc/svc_xprt.c                    | 10 +----
 net/sunrpc/svcsock.c                     | 15 ++++---
 net/sunrpc/xprtrdma/svc_rdma_recvfrom.c  |  8 +++-
 net/sunrpc/xprtrdma/svc_rdma_rw.c        |  2 +-
 net/sunrpc/xprtrdma/svc_rdma_sendto.c    | 16 ++++++--
 net/sunrpc/xprtrdma/svc_rdma_transport.c |  2 +-
 13 files changed, 97 insertions(+), 58 deletions(-)

-- 
2.49.0