Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=406a7ea97d9dc1a9348ba92c4cd0e7c678185c4c
Commit:     406a7ea97d9dc1a9348ba92c4cd0e7c678185c4c
Parent:     39325bd03fc16d903f1e0f51104436d939899c8c
Author:     Frank Filz <[EMAIL PROTECTED]>
AuthorDate: Tue Nov 27 11:34:05 2007 -0800
Committer:  J. Bruce Fields <[EMAIL PROTECTED]>
CommitDate: Fri Feb 1 16:42:06 2008 -0500

    nfsd: Allow AIX client to read dir containing mountpoints
    
    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.
    
    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 <[EMAIL PROTECTED]>
    Signed-off-by: J. Bruce Fields <[EMAIL PROTECTED]>
---
 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 bf1e792..b0592e7 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)
+               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);
-
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