libceph: tolerate addrvecs with multiple entries of the same type

libceph: tolerate addrvecs with multiple entries of the same type

ceph_decode_entity_addrvec() rejects any addrvec containing more than
one entry that matches the requested msgr type (LEGACY or MSGR2),
logging "another match of type N in addrvec" and returning -EINVAL.

Some admin tooling (e.g. pveceph mon create from Proxmox VE) generates
addrvecs with multiple same-type entries when public_network lists more
than one CIDR: it picks one local IP per subnet and emits both a v2 and
a v1 entry for each IP.  Monmaps shaped this way cause:

  libceph: mon0 (1)10.10.10.15:6789 session established
  libceph: another match of type 1 in addrvec
  libceph: problem decoding monmap, -22

No Ceph code uses the extra entries: since Nautilus, the userspace
messenger (AsyncMessenger) unconditionally picks the first address of
the requested type and ignores any subsequent matches.

Match that behavior: use the first matching entry and silently skip any
subsequent ones.  This is a compatibility fix for existing deployments
and does not enable dual-stack or multi-subnet address selection.

[ idryomov: tweak ceph_decode_entity_addrvec() comment ]

Cc: stable@vger.kernel.org
Fixes: a5cbd5fc22d5 ("libceph, ceph: get and handle cluster maps with addrvecs")
Link: https://bugzilla.proxmox.com/show_bug.cgi?id=7518
Signed-off-by: Kefu Chai <k.chai@proxmox.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>