net: Kernel side filtering for route dumps

From: David Ahern <[email protected]>

Implement kernel side filtering of route dumps by protocol (e.g., which routing daemon installed the route), route type (e.g., unicast), table id and nexthop device.

iproute2 has been doing this filtering in userspace for years; pushing the filters to the kernel side reduces the amount of data the kernel sends and reduces wasted cycles on both sides processing unwanted data. These initial options provide a huge improvement for efficiently examining routes on large scale systems.

v2
- better handling of requests for a specific table. Rather than walking the hash of all tables, lookup the specific table and dump it
- refactor mr_rtm_dumproute moving the loop over the table into a helper that can be invoked directly
- add hook to return NLM_F_DUMP_FILTERED in DONE message to ensure it is returned even when the dump returns nothing

David Ahern (11):
netlink: Add answer_flags to netlink_callback
net: Add struct for fib dump filter
net/ipv4: Plumb support for filtering route dumps net/ipv6: Plumb support for filtering route dumps net/mpls: Plumb support for filtering route dumps
ipmr: Refactor mr_rtm_dumproute
net: Plumb support for filtering ipv4 and ipv6 multicast route dumps
net: Enable kernel side filtering of route dumps net/mpls: Handle kernel side filtering of route dumps net/ipv6: Bail early if user only wants cloned entries net/ipv4: Bail early if user only wants prefix entries

 include/linux/mroute_base.h |  11 +++-
 include/linux/netlink.h     |   1 +
 include/net/ip6_route.h     |   1 +
 include/net/ip_fib.h        |  17 ++++--
 net/ipv4/fib_frontend.c     |  76 ++++++++++++++++++++++----
 net/ipv4/fib_trie.c         |  37 +++++++++----
 net/ipv4/ipmr.c             |  22 ++++++--
 net/ipv4/ipmr_base.c        | 126 ++++++++++++++++++++++++++++++++------------
 net/ipv6/ip6_fib.c          |  34 +++++++++---
 net/ipv6/ip6mr.c            |  21 ++++++--
 net/ipv6/route.c            |  40 +++++++++++---
 net/mpls/af_mpls.c          |  92 +++++++++++++++++++++++++++-----
 net/netlink/af_netlink.c    |   3 +-
 13 files changed, 386 insertions(+), 95 deletions(-)

2.11.0