From: Peter Staubach Subject: Re: [PATCH 038/100] nfsd: Allow AIX client to read dir containing mountpoints Date: Fri, 08 Feb 2008 15:07:57 -0500 Message-ID: <47ACB69D.60704@redhat.com> References: <20080125231521.GG25141@fieldses.org> <1201303040-7779-23-git-send-email-bfields@citi.umich.edu> <1201303040-7779-24-git-send-email-bfields@citi.umich.edu> <1201303040-7779-25-git-send-email-bfields@citi.umich.edu> <1201303040-7779-26-git-send-email-bfields@citi.umich.edu> <1201303040-7779-27-git-send-email-bfields@citi.umich.edu> <1201303040-7779-28-git-send-email-bfields@citi.umich.edu> <1201303040-7779-29-git-send-email-bfields@citi.umich.edu> <1201303040-7779-30-git-send-email-bfields@citi.umich.edu> <1201303040-7779-31-git-send-email-bfields@citi.umich.edu> <1201303040-7779-32-git-send-email-bfields@citi.umich.edu> <1201303040-7779-33-git-send-email-bfields@citi.umich.edu> <1201303040-7779-34-git-send-email-bfields@citi.umich.edu> <1201303040-7779-35-git-send-email-bfields @citi.umich.edu> <1201303040-7779-36-git-send-email-bfields@citi.umich.edu> <1201303040-7779-37-git-send-email-bfields@citi.umich.edu> <1201303040-7779-38-git-send-email-bfields@citi.umich.! edu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: linux-nfs@vger.kernel.org, Frank Filz To: "J. Bruce Fields" Return-path: Received: from mx1.redhat.com ([66.187.233.31]:50130 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760408AbYBHUJX (ORCPT ); Fri, 8 Feb 2008 15:09:23 -0500 In-Reply-To: <1201303040-7779-38-git-send-email-bfields@citi.umich.edu> Sender: linux-nfs-owner@vger.kernel.org List-ID: J. Bruce Fields wrote: > From: Frank Filz > > This patch addresses a compatibility issue with a Linux NFS server and > AIX NFS client. > > I have exported /export as fsid=0 with sec=krb5:krb5i > I have mount --bind /home onto /export/home > I have exported /export/home with sec=krb5i > > The AIX client mounts / -o sec=krb5:krb5i onto /mnt > > If I do an ls /mnt, the AIX client gets a permission error. Looking at > the network traceIwe see a READDIR looking for attributes > FATTR4_RDATTR_ERROR and FATTR4_MOUNTED_ON_FILEID. The response gives a > NFS4ERR_WRONGSEC which the AIX client is not expecting. > > Since the AIX client is only asking for an attribute that is an > attribute of the parent file system (pseudo root in my example), it > seems reasonable that there should not be an error. > > Can we go through this explanation one more time, a little more slowly, please? I am not following it. It is my understanding that FATTR4_RDATTR_ERROR simply says to return a magic value to indicate that the requested attributes could not be retrieved during a READDIR operation. It is also my understanding that the FATTR4_MOUNTED_ON_FILEID returns either the fileid of the entry in the directory or the fileid of the directory which is the root of the mount point which is mounted on top of the entry in the directory. So, given all of this, why is the right thing to do to return the fileid of the entry in the directory, even though it is mounted on top of? Why isn't the right thing to do to return NFS4ERR_WRONGSEC per page 206 in rfc3530? Perhaps I am not following the bind mount properly? A little more below -- > In discussing this issue with Bruce Fields, I initially proposed > ignoring the error in nfsd4_encode_dirent_fattr() if all that was being > asked for was FATTR4_RDATTR_ERROR and FATTR4_MOUNTED_ON_FILEID, however, > Bruce suggested that we avoid calling cross_mnt() if only these > attributes are requested. > > The following patch implements bypassing cross_mnt() if only > FATTR4_RDATTR_ERROR and FATTR4_MOUNTED_ON_FILEID are called. Since there > is some complexity in the code in nfsd4_encode_fattr(), I didn't want to > duplicate code (and introduce a maintenance nightmare), so I added a > parameter to nfsd4_encode_fattr() that indicates whether it should > ignore cross mounts and simply fill in the attribute using the passed in > dentry as opposed to it's parent. > > Signed-off-by: Frank Filz > Signed-off-by: J. Bruce Fields > --- > fs/nfsd/nfs4proc.c | 2 +- > fs/nfsd/nfs4xdr.c | 27 ++++++++++++++++++++++----- > include/linux/nfsd/xdr4.h | 2 +- > 3 files changed, 24 insertions(+), 7 deletions(-) > > diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c > index 18ead17..c593db0 100644 > --- a/fs/nfsd/nfs4proc.c > +++ b/fs/nfsd/nfs4proc.c > @@ -750,7 +750,7 @@ _nfsd4_verify(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, > cstate->current_fh.fh_export, > cstate->current_fh.fh_dentry, buf, > &count, verify->ve_bmval, > - rqstp); > + rqstp, 0); > > /* this means that nfsd4_encode_fattr() ran out of space */ > if (status == nfserr_resource && count == 0) > diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c > index 25c7ae2..2d94b9b 100644 > --- a/fs/nfsd/nfs4xdr.c > +++ b/fs/nfsd/nfs4xdr.c > @@ -1453,7 +1453,7 @@ static __be32 fattr_handle_absent_fs(u32 *bmval0, u32 *bmval1, u32 *rdattr_err) > __be32 > nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp, > struct dentry *dentry, __be32 *buffer, int *countp, u32 *bmval, > - struct svc_rqst *rqstp) > + struct svc_rqst *rqstp, int ignore_crossmnt) > { > u32 bmval0 = bmval[0]; > u32 bmval1 = bmval[1]; > @@ -1833,7 +1833,12 @@ out_acl: > if (bmval1 & FATTR4_WORD1_MOUNTED_ON_FILEID) { > if ((buflen -= 8) < 0) > goto out_resource; > - if (exp->ex_mnt->mnt_root->d_inode == dentry->d_inode) { > + /* > + * Get parent's attributes if not ignoring crossmount > + * and this is the root of a cross-mounted filesystem. > + */ > + if (ignore_crossmnt == 0 && > + exp->ex_mnt->mnt_root->d_inode == dentry->d_inode) { > err = vfs_getattr(exp->ex_mnt->mnt_parent, > exp->ex_mnt->mnt_mountpoint, &stat); > if (err) > @@ -1869,13 +1874,25 @@ nfsd4_encode_dirent_fattr(struct nfsd4_readdir *cd, > struct svc_export *exp = cd->rd_fhp->fh_export; > struct dentry *dentry; > __be32 nfserr; > + int ignore_crossmnt = 0; > > dentry = lookup_one_len(name, cd->rd_fhp->fh_dentry, namlen); > if (IS_ERR(dentry)) > return nfserrno(PTR_ERR(dentry)); > > exp_get(exp); > - if (d_mountpoint(dentry)) { > + /* > + * In the case of a mountpoint, the client may be asking for > + * attributes that are only properties of the underlying filesystem > + * as opposed to the cross-mounted file system. In such a case, > + * we will not follow the cross mount and will fill the attribtutes > + * directly from the mountpoint dentry. > + */ > + if (d_mountpoint(dentry) && > + (cd->rd_bmval[0] & ~FATTR4_WORD0_RDATTR_ERROR) == 0 && > + (cd->rd_bmval[1] & ~FATTR4_WORD1_MOUNTED_ON_FILEID) == 0) > These are some odd looking tests. What is the real intention for these tests? They don't test just for requests with just RDATTR_ERROR and MOUNTED_ON_FILEID set. They will trigger whether or not either or neither is set as well. Thanx... ps > + ignore_crossmnt = 1; > + else if (d_mountpoint(dentry)) { > int err; > > /* > @@ -1894,7 +1911,7 @@ nfsd4_encode_dirent_fattr(struct nfsd4_readdir *cd, > > } > nfserr = nfsd4_encode_fattr(NULL, exp, dentry, p, buflen, cd->rd_bmval, > - cd->rd_rqstp); > + cd->rd_rqstp, ignore_crossmnt); > out_put: > dput(dentry); > exp_put(exp); > @@ -2048,7 +2065,7 @@ nfsd4_encode_getattr(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4 > buflen = resp->end - resp->p - (COMPOUND_ERR_SLACK_SPACE >> 2); > nfserr = nfsd4_encode_fattr(fhp, fhp->fh_export, fhp->fh_dentry, > resp->p, &buflen, getattr->ga_bmval, > - resp->rqstp); > + resp->rqstp, 0); > if (!nfserr) > resp->p += buflen; > return nfserr; > diff --git a/include/linux/nfsd/xdr4.h b/include/linux/nfsd/xdr4.h > index b0ddfb4..27bd3e3 100644 > --- a/include/linux/nfsd/xdr4.h > +++ b/include/linux/nfsd/xdr4.h > @@ -441,7 +441,7 @@ void nfsd4_encode_operation(struct nfsd4_compoundres *, struct nfsd4_op *); > void nfsd4_encode_replay(struct nfsd4_compoundres *resp, struct nfsd4_op *op); > __be32 nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp, > struct dentry *dentry, __be32 *buffer, int *countp, > - u32 *bmval, struct svc_rqst *); > + u32 *bmval, struct svc_rqst *, int ignore_crossmnt); > extern __be32 nfsd4_setclientid(struct svc_rqst *rqstp, > struct nfsd4_compound_state *, > struct nfsd4_setclientid *setclid); >