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

[Benny Halevy <bhalevy@panasas.com>]

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));
>>> +		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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