[PATCH net-next v3 0/2] net: rds: convert rds to getsockopt_iter

[Breno Leitao <leitao@debian.org>]

This series continues the conversion of the remaining proto_ops getsockopt
callbacks to the new getsockopt_iter callback introduced in commit
67fab22a7adc ("net: add getsockopt_iter callback to proto_ops"), this time
for RDS.

RDS is a little more involved than the protocols converted so far, because
the RDS_INFO_* options snapshot kernel state directly into the destination
buffer: the info producers memcpy into the pages under a spinlock via
kmap_atomic() and so must not fault.

The conversion preserves that model — it obtains the same page array and
starting offset from opt->iter_out with iov_iter_extract_pages(),
preallocating the array so the iterator fills it in place, and leaves
the rds_info_iterator / rds_info_copy machinery and all producer
callbacks unchanged; kernel (ITER_KVEC) buffers remain unsupported on
the RDS_INFO path, as before.

I've vibe-coded a kselftest exercising both the simple options and the
RDS_INFO_* snapshot path, feel free to drop it in case this is not
useful.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
Changes in v3:
- Resolved the conflict with net-next
- Added additional tags (assisted-by and reviewes)
- Link to v2: https://lore.kernel.org/r/20260605-getsock_more-v2-0-80f38cdb8706@debian.org

Changes in v2:
- rds: reject non-user-backed buffers with !user_backed_iter() instead of
  iov_iter_is_kvec() on the RDS_INFO path (Allison Henderson)
- rds: gate the page unpin on iov_iter_extract_will_pin() and comment the
  implicit pin (Allison Henderson)
- selftest: size the snapshot mmap from the probed length instead of a fixed
  two pages (Allison Henderson)
- Add a new patch to fix a concern raised by Sashiko.
- Link to v1:
https://lore.kernel.org/r/20260603-getsock_more-v1-0-43b8d40c8849@debian.org

---
Breno Leitao (2):
      selftests: net: rds: add getsockopt() conversion test
      rds: convert to getsockopt_iter

 net/rds/af_rds.c                             |  36 ++---
 net/rds/info.c                               |  76 +++++-----
 net/rds/info.h                               |   3 +-
 tools/testing/selftests/net/rds/.gitignore   |   1 +
 tools/testing/selftests/net/rds/Makefile     |   4 +
 tools/testing/selftests/net/rds/getsockopt.c | 208 +++++++++++++++++++++++++++
 6 files changed, 278 insertions(+), 50 deletions(-)
---
base-commit: 903db046d5579bef0ea699eae4b279dd6455fc9f
change-id: 20260603-getsock_more-46be8d1c56fd

Best regards,
-- 
Breno Leitao <leitao@debian.org>