Re: [PATCH 13/15] NFSv41: Clean up exclusive create

[Benny Halevy <bhalevy@panasas.com>]

On Jun. 15, 2010, 12:19 -0400, Trond Myklebust <Trond.Myklebust@netapp.com> wrote:
> On Tue, 2010-06-15 at 12:08 -0400, Benny Halevy wrote:
>> On Jun. 15, 2010, 11:50 -0400, Trond Myklebust <Trond.Myklebust@netapp.com> wrote:
>>> On Mon, 2010-06-14 at 19:13 -0400, Benny Halevy wrote:
>>>> On Jun. 14, 2010, 17:51 -0400, Trond Myklebust <Trond.Myklebust@netapp.com> wrote:
>>>>> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
>>>>> ---
>>>>>  fs/nfs/nfs4proc.c       |   17 ++++++-----------
>>>>>  include/linux/nfs_xdr.h |    6 ++++--
>>>>>  2 files changed, 10 insertions(+), 13 deletions(-)
>>>>>
>>>>> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
>>>>> index ef613ea..e9913de 100644
>>>>> --- a/fs/nfs/nfs4proc.c
>>>>> +++ b/fs/nfs/nfs4proc.c
>>>>> @@ -744,19 +744,14 @@ static struct nfs4_opendata *nfs4_opendata_alloc(struct path *path,
>>>>>  	p->o_arg.server = server;
>>>>>  	p->o_arg.bitmask = server->attr_bitmask;
>>>>>  	p->o_arg.claim = NFS4_OPEN_CLAIM_NULL;
>>>>> -	if (flags & O_EXCL) {
>>>>> -		if (nfs4_has_persistent_session(server->nfs_client)) {
>>>>> -			/* GUARDED */
>>>>> -			p->o_arg.u.attrs = &p->attrs;
>>>>> -			memcpy(&p->attrs, attrs, sizeof(p->attrs));
>>>>
>>>> What about this case?
>>>> Aren't we losing the attrs?
>>>
>>> I'm not sure what you mean. Are you asking what will happen if someone
>>> sets O_EXCL without setting O_CREAT? We don't call encode_createmode at
>>> all in that case. Otherwise, see below.
>>>
>>
>> It looks like in the O_CREAT|O_EXCL case with persistent session
>> the attrs passed in to nfs4_opendata_alloc are not copied to p->attrs
>> and p->o_arg.u.attrs is not set.
>> Then later on, in encode_createmode, in the respective path, we still use it:
>> 			if (nfs4_has_persistent_session(clp)) {
>> 				*p = cpu_to_be32(NFS4_CREATE_GUARDED);
>> 				encode_attrs(xdr, arg->u.attrs, arg->server);
>> 			} else {
>>
>> Benny
>>
>>> Cheers
>>>   Trond
>>>
>>>>
>>>>> -		} else { /* EXCLUSIVE4_1 */
>>>>> -			u32 *s = (u32 *) p->o_arg.u.verifier.data;
>>>>> -			s[0] = jiffies;
>>>>> -			s[1] = current->pid;
>>>>> -		}
>>>>> -	} else if (flags & O_CREAT) {
>>>>> +	if (flags & O_CREAT) {
>>>>> +		u32 *s;
>>>>> +
>>>>>  		p->o_arg.u.attrs = &p->attrs;
>>>>>  		memcpy(&p->attrs, attrs, sizeof(p->attrs));
>                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 
> Why isn't this sufficient?
> 

Duh. Sorry, I missed that.

Benny

>>>>> +		s = (u32 *) p->o_arg.u.verifier.data;
>>>>> +		s[0] = jiffies;
>>>>> +		s[1] = current->pid;
>>>>>  	}
>>>>>  	p->c_arg.fh = &p->o_res.fh;
>>>>>  	p->c_arg.stateid = &p->o_res.stateid;
>>>>> diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
>>>>> index 51914d7..a319cb9 100644
>>>>> --- a/include/linux/nfs_xdr.h
>>>>> +++ b/include/linux/nfs_xdr.h
>>>>> @@ -196,8 +196,10 @@ struct nfs_openargs {
>>>>>  	__u64                   clientid;
>>>>>  	__u64                   id;
>>>>>  	union {
>>>>> -		struct iattr *  attrs;    /* UNCHECKED, GUARDED */
>>>>> -		nfs4_verifier   verifier; /* EXCLUSIVE */
>>>>> +		struct {
>>>>> +			struct iattr *  attrs;    /* UNCHECKED, GUARDED */
>>>>> +			nfs4_verifier   verifier; /* EXCLUSIVE */
>>>>> +		};
>>>>>  		nfs4_stateid	delegation;		/* CLAIM_DELEGATE_CUR */
>>>>>  		fmode_t		delegation_type;	/* CLAIM_PREVIOUS */
>>>>>  	} u;
>>>>
>>>
>>>
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> 
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