Hi Trond,
Trond Myklebust:
> On Fri, 2011-01-14 at 13:16 -0500, J. Bruce Fields wrote:
>> On Fri, Jan 14, 2011 at 02:45:56PM +0800, Fu Liankun wrote:
>>> The RFC3530 describes that the client's all lock operations, including those
>>> requesting non-exclusive locks, should be sent to the server for resolution,
>>> even if it holds a read open delegation. But the kernel implements like that
>>> lock operations can be performed locally when a client holds an open
>>> delegation.
>>>
>>> The following are the RFC3530 provisions for Open Delegation and File Locks:
>>>
>>> 9.4.2. Open Delegation and File Locks
>>>
>>> When a client holds a write open delegation, lock operations may be
>>> performed locally. This includes those required for mandatory file
>>> locking. This can be done since the delegation implies that there
>>> can be no conflicting locks. Similarly, all of the revalidations
>>> that would normally be associated with obtaining locks and the
>>> flushing of data associated with the releasing of locks need not be
>>> done.
>>>
>>> When a client holds a read open delegation, lock operations are not
>>> performed locally. All lock operations, including those requesting
>>> non-exclusive locks, are sent to the server for resolution.
>> Weird. Can the rfc really be right about that?
>>
>> I guess it does permit servers to allow write-locks on read-open files,
>> but it seems bizarre not to require them to break delegations in that
>> case.
>
> The ability to cache locks is one of the main reasons for holding
> delegations in the first place. Sure, the spec allows for non-posix
> locking, but the Linux client doesn't.
Would you mind tell me some about why we not support non-posix locking at NFS ?
thanks,
Mi Jinlong
>
> IOW: This patch will not be applied.
>
> Trond
>
>> --b.
>>
>>> Signed-off-by: Fu Liankun <fuliankun@xxxxxxxxxxxxxx>
>>> ---
>>> fs/nfs/nfs4proc.c | 7 -------
>>> 1 files changed, 0 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
>>> index 0f24cdf..3bba85b 100644
>>> --- a/fs/nfs/nfs4proc.c
>>> +++ b/fs/nfs/nfs4proc.c
>>> @@ -4215,13 +4215,6 @@ static int _nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock
>>> if (status < 0)
>>> goto out;
>>> down_read(&nfsi->rwsem);
>>> - if (test_bit(NFS_DELEGATED_STATE, &state->flags)) {
>>> - /* Yes: cache locks! */
>>> - /* ...but avoid races with delegation recall... */
>>> - request->fl_flags = fl_flags & ~FL_SLEEP;
>>> - status = do_vfs_lock(request->fl_file, request);
>>> - goto out_unlock;
>>> - }
>>> status = _nfs4_do_setlk(state, cmd, request, NFS_LOCK_NEW);
>>> if (status != 0)
>>> goto out_unlock;
>>> --
>>> 1.7.3.1
>>>
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