NFSD: Add POSIX draft ACL support to the NFSv4 SETATTR operation

NFSD: Add POSIX draft ACL support to the NFSv4 SETATTR operation

The POSIX ACL extension to NFSv4 enables clients to set access
and default ACLs via FATTR4_POSIX_ACCESS_ACL and
FATTR4_POSIX_DEFAULT_ACL attributes. Integration of these
attributes into SETATTR processing requires wiring them through
the nfsd_attrs structure and ensuring proper cleanup on all
code paths.

This patch connects the na_pacl and na_dpacl fields in
nfsd_attrs to the decoded ACL pointers from the NFSv4 SETATTR
decoder. Ownership of these ACL references transfers to attrs
immediately after initialization, with the decoder's pointers
cleared to NULL. This transfer ensures nfsd_attrs_free()
releases the ACLs on normal completion, while new error paths
call posix_acl_release() directly when cleanup occurs before
nfsd_attrs_free() runs.

Early returns in the nfsd4_setattr() function gain conversions
to goto statements that branch to proper cleanup handlers.
Error paths before fh_want_write() branch to out_err for ACL
release only; paths after fh_want_write() use the existing out
label for full cleanup via nfsd_attrs_free().

The patch adds mutual exclusion between NFSv4 ACLs (sa_acl) and
POSIX ACLs. Setting both types simultaneously returns
nfserr_inval because these ACL models cannot coexist on the
same file object.

Signed-off-by: Rick Macklem <rmacklem@uoguelph.ca>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>