linux-kernel - Re: [NFS] [PATCH 2/2] nfs4: on a O_EXCL OPEN make sure the SETATTR sets the fields holding the verifier

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Message-Id: <20070605153527.bdc6e4da.jlayton@redhat.com>
Date:	Tue, 5 Jun 2007 15:35:27 -0400
From:	Jeff Layton <jlayton@...hat.com>
To:	Trond Myklebust <trond.myklebust@....uio.no>
Cc:	nfsv4@...ux-nfs.org, nfs@...ts.sourceforge.net,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [NFS] [PATCH 2/2] nfs4: on a O_EXCL OPEN make sure the SETATTR
 sets the fields holding the verifier

On Tue, 05 Jun 2007 14:13:02 -0400
Trond Myklebust <trond.myklebust@....uio.no> wrote:

> On Tue, 2007-06-05 at 13:56 -0400, Jeff Layton wrote:
> > The Linux NFS4 client simply skips over the bitmask in an O_EXCL open
> > call and so it doesn't bother to reset any fields that may be holding
> > the verifier. This patch has us save the first two words of the bitmask
> > (which is all the current client has #defines for). The client then
> > later checks this bitmask and turns on the appropriate flags in the
> > sattr->ia_verify field for the following SETATTR call.
> > 
> > This patch only currently checks to see if the server used the atime
> > and mtime slots for the verifier (which is what the Linux server uses
> > for this). I'm not sure of what other fields the server could
> > reasonably use, but adding checks for others should be trivial.
> > 
> > Signed-off-by: Jeff Layton <jlayton@...hat.com>
> > 
> > diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> > index 8e46e3e..34ddd66 100644
> > --- a/fs/nfs/nfs4proc.c
> > +++ b/fs/nfs/nfs4proc.c
> > @@ -955,6 +955,22 @@ static struct nfs4_state *nfs4_open_delegated(struct inode *inode, int flags, st
> >  }
> >  
> >  /*
> > + * on an EXCLUSIVE create, the server should send back a bitmask with FATTR4-*
> > + * fields corresponding to attributes that were used to store the verifier.
> > + * Make sure we clobber those fields in the later setattr call
> > + */
> > +static inline void nfs4_exclusive_attrset (struct nfs4_opendata *opendata, struct iattr *sattr)
> > +{
> > +	if ((opendata->o_res.attrset[1] & FATTR4_WORD1_TIME_ACCESS) &&
> > +	    !(sattr->ia_valid & ATTR_ATIME_SET))
> > +		sattr->ia_valid |= ATTR_ATIME;
> > +
> > +	if ((opendata->o_res.attrset[1] & FATTR4_WORD1_TIME_MODIFY) &&
> > +	    !(sattr->ia_valid & ATTR_MTIME_SET))
> > +		sattr->ia_valid |= ATTR_MTIME;
> > +}
> > +
> > +/*
> >   * Returns a referenced nfs4_state
> >   */
> >  static int _nfs4_do_open(struct inode *dir, struct dentry *dentry, int flags, struct iattr *sattr, struct rpc_cred *cred, struct nfs4_state **res)
> > @@ -985,6 +1001,9 @@ static int _nfs4_do_open(struct inode *dir, struct dentry *dentry, int flags, st
> >  	if (status != 0)
> >  		goto err_opendata_free;
> >  
> > +	if (opendata->o_arg.open_flags & O_EXCL)
> > +		nfs4_exclusive_attrset(opendata, sattr);
> > +
> >  	status = -ENOMEM;
> >  	state = nfs4_opendata_to_nfs4_state(opendata);
> >  	if (state == NULL)
> > @@ -1787,6 +1806,7 @@ nfs4_proc_create(struct inode *dir, struct dentry *dentry, struct iattr *sattr,
> >  		status = nfs4_do_setattr(state->inode, &fattr, sattr, state);
> >  		if (status == 0)
> >  			nfs_setattr_update_inode(state->inode, sattr);
> > +		nfs_refresh_inode(state->inode, &fattr);
>                   ^^^^ should be nfs_post_op_update_inode() to ensure
> that the attribute cache gets invalidated if the server fails to return
> the post-op attributes.
> 

It looks like nfs3_proc_create() uses nfs_refresh_inode in this spot (which was
why I initially used one here). Should it also be changed to use
nfs_post_op_update_inode(), or is it correct as-is?


> >  	}
> >  	if (status == 0 && nd != NULL && (nd->flags & LOOKUP_OPEN))
> >  		status = nfs4_intent_set_file(nd, dentry, state);
> > diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
> > index 4eb8a59..b281c83 100644
> > --- a/fs/nfs/nfs4xdr.c
> > +++ b/fs/nfs/nfs4xdr.c
> > @@ -3313,7 +3313,7 @@ static int decode_delegation(struct xdr_stream *xdr, struct nfs_openres *res)
> >  static int decode_open(struct xdr_stream *xdr, struct nfs_openres *res)
> >  {
> >          __be32 *p;
> > -        uint32_t bmlen;
> > +        uint32_t savewords, bmlen, i;
> >          int status;
> >  
> >          status = decode_op_hdr(xdr, OP_OPEN);
> > @@ -3331,7 +3331,15 @@ static int decode_open(struct xdr_stream *xdr, struct nfs_openres *res)
> >                  goto xdr_error;
> >  
> >          READ_BUF(bmlen << 2);
> > -        p += bmlen;
> > +
> > +	savewords = bmlen > NFS_OPENRES_ATTRSET_WORDS ?
> > +			NFS_OPENRES_ATTRSET_WORDS : bmlen;
>                       ^^^^ min_t(bmlen, NFS_OPENRES_ATTRSET_WORDS, uint32_t);
> > +
> > +	for (i = 0; i < savewords; ++i) 
> > +		READ32(res->attrset[i]);
> > +
> > +	p += (bmlen - savewords);
> > +
> >  	return decode_delegation(xdr, res);
> >  xdr_error:
> >  	dprintk("%s: Bitmap too large! Length = %u\n", __FUNCTION__, bmlen);
> > diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
> > index f8c55e5..f050a27 100644
> > --- a/include/linux/nfs_xdr.h
> > +++ b/include/linux/nfs_xdr.h
> > @@ -133,6 +133,7 @@ struct nfs_openargs {
> >  	__u32			claim;
> >  };
> >  
> > +#define NFS_OPENRES_ATTRSET_WORDS	2
> 
>    Could you rename this to NFS4_BITMAP_SIZE and put it into
> include/linux/nfs4.h, please.
> 
> >  struct nfs_openres {
> >  	nfs4_stateid            stateid;
> >  	struct nfs_fh           fh;
> > @@ -145,6 +146,7 @@ struct nfs_openres {
> >  	nfs4_stateid		delegation;
> >  	__u32			do_recall;
> >  	__u64			maxsize;
> > +	__u32			attrset[NFS_OPENRES_ATTRSET_WORDS];
> >  };
> >  
> >  /*
> > 
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> 


-- 
Jeff Layton <jlayton@...hat.com>
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