[net-next,0/8] crypto, splice, net: Make AF_ALG handle sendmsg(MSG_SPLICE_PAGES)

Message

David Howells May 26, 2023, 2:30 p.m. UTC

Here's the fourth tranche of patches towards providing a MSG_SPLICE_PAGES
internal sendmsg flag that is intended to replace the ->sendpage() op with
calls to sendmsg().  MSG_SPLICE_PAGES is a hint that tells the protocol
that it should splice the pages supplied if it can.

This set consists of the following parts:

 (1) Move netfs_extract_iter_to_sg() to somewhere more general and rename
     it to drop the "netfs" prefix.  We use this to extract directly from
     an iterator into a scatterlist.

 (2) Make AF_ALG use iov_iter_extract_pages().  This has the additional
     effect of pinning pages obtained from userspace rather than taking
     refs on them.  Pages from kernel-backed iterators would not be pinned,
     but AF_ALG isn't really meant for use by kernel services.

 (3) Change AF_ALG still further to use extract_iter_to_sg().

 (4) Make af_alg_sendmsg() support MSG_SPLICE_PAGES support and make
     af_alg_sendpage() just a wrapper around sendmsg().  This has to take
     refs on the pages pinned for the moment.

 (5) Make hash_sendmsg() support MSG_SPLICE_PAGES by simply ignoring it.
     hash_sendpage() is left untouched to be removed later, after the
     splice core has been changed to call sendmsg().

I've pushed the patches here also:

	https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=sendpage-4

David

Link: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=51c78a4d532efe9543a4df019ff405f05c6157f6 # part 1

David Howells (8):
  Move netfs_extract_iter_to_sg() to lib/scatterlist.c
  Drop the netfs_ prefix from netfs_extract_iter_to_sg()
  crypto: af_alg: Pin pages rather than ref'ing if appropriate
  crypto: af_alg: Use extract_iter_to_sg() to create scatterlists
  crypto: af_alg: Indent the loop in af_alg_sendmsg()
  crypto: af_alg: Support MSG_SPLICE_PAGES
  crypto: af_alg: Convert af_alg_sendpage() to use MSG_SPLICE_PAGES
  crypto: af_alg/hash: Support MSG_SPLICE_PAGES

 crypto/af_alg.c             | 183 +++++++++++-------------
 crypto/algif_aead.c         |  34 ++---
 crypto/algif_hash.c         | 110 +++++++++------
 crypto/algif_skcipher.c     |  10 +-
 fs/cifs/smb2ops.c           |   4 +-
 fs/cifs/smbdirect.c         |   2 +-
 fs/netfs/iterator.c         | 266 -----------------------------------
 include/crypto/if_alg.h     |   7 +-
 include/linux/netfs.h       |   4 -
 include/linux/scatterlist.h |   1 +
 include/linux/uio.h         |   5 +
 lib/scatterlist.c           | 267 ++++++++++++++++++++++++++++++++++++
 12 files changed, 449 insertions(+), 444 deletions(-)