On Mon, Aug 6, 2018 at 10:46 AM, Chuck Lever <chuck.lever@xxxxxxxxxx> wrote: > > >> On Aug 2, 2018, at 12:42 PM, Olga Kornievskaia <aglo@xxxxxxxxx> wrote: >> >> On Thu, Aug 2, 2018 at 11:14 AM, Olga Kornievskaia <aglo@xxxxxxxxx> wrote: >>> Hi folks, >>> >>> There is no documentation of this behavior but when "noresvport" is >>> specified, the client will not try to re-use the port upon connection >>> re-establishement. Is this an oversight or a desired behavior (ie., >>> client doesn't need to be conservative and re-use ports)? >>> >>> Thank you. >> >> I'm going to speculate on the reason myself and would like to hear >> some folks thoughts. >> >> When we specify "noresvport" we use port=0 value that tells the kernel >> - use any port. When connection is re-established port=0 so NFS has no >> control over which port the kernel will choose. >> >> When client re-establishes the connection with a different port, that >> has an effect on the server's replay cache. Any thoughts on that? >> >> Should the client remember which non-privileged port it used and then >> the next time request a specific port? > > The basic constraint is that: > > If the client actively disconnects, or if the client is using an NFSv4 > session, then for a fresh connection the client is free to use any > available source port in the range selected by the "resvport" mount > option. > > If there is no NFSv4 session and the server or the network transport > actively disconnects (say, due to a keep-alive timeout), the client > should attempt to use the same source port as the previous connection > in order to preserve DRC content on the server. Hi Chuck, Thanks for the reply. I'm considering your 2nd case where the server reset the connection and client is re-establishing it and this is a v3 mount (this DRC is important). When "noresvport" is specified, then the kernel makes no attempts at re-use the same non-reserved port. However, I'm not sure it is possible to re-use a non-reserved port. Given this behavior, shouldn't we be discouraging folks to mount with v3 and "noresvport" option? > > >> Is that possible? > > > -- > Chuck Lever > > > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
