Re: [NFS] Re: Non-blocking lock requests during the grace period

From: Juan Gomez (juang@us.ibm.com)
Date: Tue Nov 19 2002 - 13:06:11 EST


Mike,

I agree with the F_GETLK part, as I pointed out to Trond earlier. However,
I feel it is odd to block a client for about one minutre when it issues
"non-blocking" lock requests. I have seen that Solaris code does so but
still feels odd and it may conflict with what most programmers expect,
though I see your point, perhaps if this was well documented in man pages
there would not be a problem. In Linux this is not the case.

Juan

|---------+---------------------------->
| | mike.kupfer@sun.c|
| | om |
| | Sent by: |
| | kupfer@athyra.eng|
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| | 11/18/02 05:04 PM|
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>-------------------------------------------------------------------------------------------------------------------------|
  | |
  | To: trond.myklebust@fys.uio.no |
  | cc: Juan Gomez/Almaden/IBM@IBMUS, linux-kernel@vger.kernel.org, nfs@lists.sourceforge.net |
  | Subject: Re: [NFS] Re: Non-blocking lock requests during the grace period |
  | |
  | |
>-------------------------------------------------------------------------------------------------------------------------|

>>>>> "Trond" == Trond Myklebust <trond.myklebust@fys.uio.no> writes:

>>>>> " " == Juan Gomez <juang@us.ibm.com> writes:

>> (note that F_GETLK man page does not provide EAGAIN as a
>> possible error code).

F_GETLK indicates a conflict by changing the arg struct to show the
conflicting lock.

As for the original topic, I would hesitate before changing the client
locking code to return EAGAIN just because the server is in its grace
period. The "blocking" or "non-blocking" behavior is tied to what
happens when there is already a lock that conflicts with the requested
one. When the server is in the grace period, it's unknown as to
whether there is already a lock that conflicts with the requested
one.

Mike Kupfer mike.kupfer@sun.com
Solaris File Sharing Speaking for myself,
not for Sun.

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