[PATCH v5 00/19] 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 v4:
* Replace the use of rq_vec instead of allocating it dynamically

Changes since v3:
* Improved the rdma_rw context count estimate
* Dropped "NFSD: Remove NFSSVC_MAXBLKSIZE from .pc_xdrressize"
* Cleaned up the max size macros a bit
* Completed the implementation of adjustable max_block_size

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

Chuck Lever (19):
  svcrdma: Reduce the number of rdma_rw contexts per-QP
  sunrpc: Add a helper to derive maxpages from sv_max_mesg
  sunrpc: Remove backchannel check in svc_init_buffer()
  sunrpc: Replace the rq_pages array with dynamically-allocated memory
  sunrpc: Replace the rq_bvec array with dynamically-allocated memory
  NFSD: Use rqstp->rq_bvec in nfsd_iter_read()
  NFSD: De-duplicate the svc_fill_write_vector() call sites
  SUNRPC: Export xdr_buf_to_bvec()
  NFSD: Use rqstp->rq_bvec in nfsd_iter_write()
  SUNRPC: Remove svc_fill_write_vector()
  SUNRPC: Remove svc_rqst :: rq_vec
  sunrpc: Adjust size of socket's receive page array dynamically
  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 NFSD_BUFSIZE
  NFSD: Remove NFSSVC_MAXBLKSIZE_V2 macro
  NFSD: Add a "default" block size
  SUNRPC: Bump the maximum payload size for the server

 fs/nfsd/nfs3proc.c                       |  5 +-
 fs/nfsd/nfs4proc.c                       | 10 +--
 fs/nfsd/nfs4state.c                      |  2 +-
 fs/nfsd/nfs4xdr.c                        |  2 +-
 fs/nfsd/nfsd.h                           | 24 +++----
 fs/nfsd/nfsproc.c                        | 13 ++--
 fs/nfsd/nfssvc.c                         |  2 +-
 fs/nfsd/nfsxdr.c                         |  4 +-
 fs/nfsd/vfs.c                            | 67 ++++++++++++++------
 fs/nfsd/vfs.h                            | 10 +--
 include/linux/sunrpc/svc.h               | 46 ++++++++------
 include/linux/sunrpc/svc_rdma.h          |  6 +-
 include/linux/sunrpc/svcsock.h           |  4 +-
 net/sunrpc/svc.c                         | 80 +++++++-----------------
 net/sunrpc/svc_xprt.c                    | 10 +--
 net/sunrpc/svcsock.c                     | 15 +++--
 net/sunrpc/xdr.c                         |  1 +
 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 | 14 +++--
 21 files changed, 170 insertions(+), 171 deletions(-)

-- 
2.49.0