NFSD: Refactor NFSv2 directory cookie encoding

The current synopsis of nfssvc_encode_nfscookie() takes a
"struct nfsd_readdirres" argument, which is used by the NFSv2
READDIR procedure.

xdrgen defines a distinct argument structure for this procedure.
With a "struct READDIRargs," the nfscookie encoder will need
generic parameter types in order to be usable.

Note that NFSD can't use the xdrgen-generated nfscookie encoder.
This is because directory cookies need to point to the previous
directory entry. Space for each cookie in the send buffer is
reserved when each directory entry is encoded; when the /next/
entry is encoded, the encoder writes its offset into that
reserved space.

As a clean-up, remove "resp->cookie_offset = 0;" :

- In nfssvc_encode_entry(), immediately after calling
  nfssvc_encode_nfscookie(), the code calls
  svcxdr_encode_entry_common() which sets a new value for
  resp->cookie_offset. The cookie_offset value was immediately
  overwritten.
- In nfsd_proc_readdir(), nfssvc_encode_nfscookie() is called as
  the last cookie encoding, and no further use of cookie_offset
  follows.
- The out_toosmall error path in nfssvc_encode_entry() continues
  to set resp->cookie_offset = 0

Acked-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260916162859.2051-29-cel@kernel.org
Signed-off-by: Chuck Lever <cel@kernel.org>

0 files changed, 0 insertions, 0 deletions