(fwd) [OpenAFS-devel] RE: afs and byte-range locking ideas

[Jeff Riegel]

----- Forwarded message from Shyh-Wei Luan <luan@almaden.ibm.com> -----

From: "Shyh-Wei Luan" <luan@almaden.ibm.com>
Subject: [OpenAFS-devel] RE: afs and byte-range locking ideas
To: riegel@almaden.ibm.com
Importance: Normal
X-Mailer: Lotus Notes Release 5.0.7  March 21, 2001
Date: Thu, 13 Dec 2001 18:22:24 -0800
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 12/13/2001 06:40:54 PM

Jeff,

Can you provide me the code point (file name and line number) which found
in the Windows client where the locking request is handled?  Or better yet,
can you send a response to the following question with the info and
hopefully a proposal/hint how to support byte-range locking among the
processes on the same client machine (if you have one)?

Shyh-Wei
---------------------- Forwarded by Shyh-Wei Luan/Almaden/IBM on 12/13/2001
06:16 PM ---------------------------

"Cameron, Frank" <Cameron@ctc.com>@openafs.org on 12/13/2001 06:03:48 PM

Sent by:  openafs-devel-admin@openafs.org


To:   "'openafs-devel@openafs.org'" <openafs-devel@openafs.org>
cc:
Subject:  [OpenAFS-devel] RE: afs and byte-range locking ideas



>Stage 1: Upgradable byte range locks at the client side
>(Client change only, assumes existing servers only)
>
>When a process on client requests a byte range lock, first attempt to
>get a full file lock on the server (if one has not already been obtained
>by this local client). If successful, locally attempt to grant the byte
>range lock.
>
>Gain: This allows multiple processes on a single host to use byte range
>locks locally, which will help multi-process apps work properly when
>components of the same app need to lock for synchronization within
>itself.

I've been looking at src/afs/VNOPS/afs_vnop_flock.c for a while.  Am I
correct in thinking that this is the only section of code that implements
the present byte-range handling scheme?  Is this the same code executed by
the Windows clients?

openafs-1.2.2:
552          /* next line makes byte range locks always succeed,
553             even when they should block */
554          if (af->l_whence != 0 || af->l_start != 0 || af->l_len != 0) {
555              DoLockWarning();
556              return 0;
557          }

-frank
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