From: Peter Staubach <staubach@redhat.com>
Subject: Re: [PATCH] 64 bit ino support for NFS server
Date: Mon, 06 Aug 2007 11:40:58 -0400
Message-ID: <46B7410A.3050202@redhat.com>
References: <46B37DE6.80706@redhat.com> <46B38206.6050504@redhat.com>
	<20070804223256.GA1155@fieldses.org>
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Cc: Neil Brown <neilb@suse.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	NFS List <nfs@lists.sourceforge.net>
To: "J. Bruce Fields" <bfields@fieldses.org>
In-Reply-To: <20070804223256.GA1155@fieldses.org>
Sender: nfs-bounces@lists.sourceforge.net
Errors-To: nfs-bounces@lists.sourceforge.net

J. Bruce Fields wrote:
> On Fri, Aug 03, 2007 at 03:29:10PM -0400, Peter Staubach wrote:
>   
>> Hi.
>>
>> Attached is a patch to modify the NFS server code to support
>> 64 bit ino's, as appropriate for the system and the NFS
>> protocol version.
>>
>> The gist of the changes is to query the underlying file system
>> for attributes and not just to use the cached attributes in the
>> inode.  For this specific purpose, the inode only contains an
>> ino field which unsigned long, which is large enough on 64 bit
>> platforms, but is not large enough on 32 bit platforms.
>>     
>
> Thanks!
>
>   
>> @@ -203,31 +203,15 @@ encode_fattr3(struct svc_rqst *rqstp, __
>>  static __be32 *
>>  encode_saved_post_attr(struct svc_rqst *rqstp, __be32 *p, struct svc_fh *fhp)
>>  {
>> -	struct inode	*inode = fhp->fh_dentry->d_inode;
>> +	if (!fhp->fh_post_saved) {
>> +		*p++ = xdr_zero;
>> +		return p;
>> +	}
>>     
>
> The caller, encode_wcc_data(), already did this check.
>
>   

True.  What a twisty maze of small passages, all alike.

The current algorithms don't look quite right to me.  I don't
think that it is valid to return a post_op_attr, which is not
atomic w.r.t. the operation, even when not returning a pre_op_attr.
Perhaps a little more cleanup might be good.  I will look into
this.

>>  	/* Attributes to follow */
>>  	*p++ = xdr_one;
>>  
>> -	*p++ = htonl(nfs3_ftypes[(fhp->fh_post_mode & S_IFMT) >> 12]);
>> -	*p++ = htonl((u32) fhp->fh_post_mode);
>> -	*p++ = htonl((u32) fhp->fh_post_nlink);
>> -	*p++ = htonl((u32) nfsd_ruid(rqstp, fhp->fh_post_uid));
>> -	*p++ = htonl((u32) nfsd_rgid(rqstp, fhp->fh_post_gid));
>> -	if (S_ISLNK(fhp->fh_post_mode) && fhp->fh_post_size > NFS3_MAXPATHLEN) {
>> -		p = xdr_encode_hyper(p, (u64) NFS3_MAXPATHLEN);
>> -	} else {
>> -		p = xdr_encode_hyper(p, (u64) fhp->fh_post_size);
>> -	}
>> -	p = xdr_encode_hyper(p, ((u64)fhp->fh_post_blocks) << 9);
>> -	*p++ = fhp->fh_post_rdev[0];
>> -	*p++ = fhp->fh_post_rdev[1];
>> -	p = encode_fsid(p, fhp);
>> -	p = xdr_encode_hyper(p, (u64) inode->i_ino);
>> -	p = encode_time3(p, &fhp->fh_post_atime);
>> -	p = encode_time3(p, &fhp->fh_post_mtime);
>> -	p = encode_time3(p, &fhp->fh_post_ctime);
>> -
>> -	return p;
>> +	return encode_fattr3(rqstp, p, fhp, &fhp->fh_post_attr);
>>     
>
> Is there a problem with the lease_get_mtime() call in encode_fattr3()?
> It looks like that could return the current time rather than the time
> that was supposedly atomic with respect to the operation.
>
>   

Sorry, I glossed over that one.  Let me address that.  Good catch.

> Dumb question: I assume it's always legal to call ->getattr while
> holding the i_mutex?
>   

Not so dumb, and I couldn't find an answer to that, either way.
I couldn't find any reason why it would be illegal, but neither
did I find explicit reasons for why it would be legal.

Does anyone else know?  This gets into the lack of complete
definition for the virtual file system layer...

Thanx for the review, Bruce.

    Thanx...

       ps


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