[PATCH v6 15/20] nfsd: allow encoding a filehandle into fattr4 without a svc_fh

[Jeff Layton <jlayton@kernel.org>]

The current fattr4 encoder requires a svc_fh in order to encode the
filehandle. This is not available in a CB_NOTIFY callback. Add a a new
"fhandle" field to struct nfsd4_fattr_args and copy the filehandle into
there from the svc_fh. CB_NOTIFY will populate it via other means.

A filehandle composed this way may still need a MAC appended on signed
exports, so generalize fh_append_mac() to operate on a bare knfsd_fh
(plus its maximum size and net) rather than a svc_fh.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 fs/nfsd/nfs4xdr.c | 36 +++++++++++++++++++++---------------
 fs/nfsd/nfsfh.c   | 10 +++++-----
 fs/nfsd/nfsfh.h   |  1 +
 3 files changed, 27 insertions(+), 20 deletions(-)

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 4fb61d05a4a7..7b19248b1503 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2715,7 +2715,7 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
 }
 
 static __be32 nfsd4_encode_nfs_fh4(struct xdr_stream *xdr,
-				   struct knfsd_fh *fh_handle)
+				   const struct knfsd_fh *fh_handle)
 {
 	return nfsd4_encode_opaque(xdr, fh_handle->fh_raw, fh_handle->fh_size);
 }
@@ -3158,6 +3158,7 @@ struct nfsd4_fattr_args {
 	struct svc_fh		*fhp;
 	struct svc_export	*exp;
 	struct dentry		*dentry;
+	struct knfsd_fh		fhandle;
 	struct kstat		stat;
 	struct kstatfs		statfs;
 	struct nfs4_acl		*acl;
@@ -3402,7 +3403,7 @@ static __be32 nfsd4_encode_fattr4_homogeneous(struct xdr_stream *xdr,
 static __be32 nfsd4_encode_fattr4_filehandle(struct xdr_stream *xdr,
 					     const struct nfsd4_fattr_args *args)
 {
-	return nfsd4_encode_nfs_fh4(xdr, &args->fhp->fh_handle);
+	return nfsd4_encode_nfs_fh4(xdr, &args->fhandle);
 }
 
 static __be32 nfsd4_encode_fattr4_fileid(struct xdr_stream *xdr,
@@ -4015,19 +4016,24 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct xdr_stream *xdr,
 		if (err)
 			goto out_nfserr;
 	}
-	if ((attrmask[0] & (FATTR4_WORD0_FILEHANDLE | FATTR4_WORD0_FSID)) &&
-	    !fhp) {
-		tempfh = kmalloc_obj(struct svc_fh);
-		status = nfserr_jukebox;
-		if (!tempfh)
-			goto out;
-		fh_init(tempfh, NFS4_FHSIZE);
-		status = fh_compose(tempfh, exp, dentry, NULL);
-		if (status)
-			goto out;
-		args.fhp = tempfh;
-	} else
-		args.fhp = fhp;
+
+	args.fhp = fhp;
+	if ((attrmask[0] & (FATTR4_WORD0_FILEHANDLE | FATTR4_WORD0_FSID))) {
+		if (!args.fhp) {
+			tempfh = kmalloc_obj(struct svc_fh);
+			status = nfserr_jukebox;
+			if (!tempfh)
+				goto out;
+			fh_init(tempfh, NFS4_FHSIZE);
+			status = fh_compose(tempfh, exp, dentry, NULL);
+			if (status)
+				goto out;
+			args.fhp = tempfh;
+		}
+		if (args.fhp)
+			fh_copy_shallow(&args.fhandle, &args.fhp->fh_handle);
+	}
+
 	if (attrmask[0] & (FATTR4_WORD0_CASE_INSENSITIVE |
 			   FATTR4_WORD0_CASE_PRESERVING)) {
 		/*
diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index b36915401758..3b29cd70d4a1 100644
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -144,16 +144,15 @@ static inline __be32 check_pseudo_root(struct dentry *dentry,
 /* Size of a file handle MAC, in 4-octet words */
 #define FH_MAC_WORDS (sizeof(__le64) / 4)
 
-static bool fh_append_mac(struct svc_fh *fhp, struct net *net)
+bool fh_append_mac(struct knfsd_fh *fh, int fh_maxsize, struct net *net)
 {
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
-	struct knfsd_fh *fh = &fhp->fh_handle;
 	siphash_key_t *fh_key = nn->fh_key;
 	__le64 hash;
 
 	if (!fh_key)
 		goto out_no_key;
-	if (fh->fh_size + sizeof(hash) > fhp->fh_maxsize)
+	if (fh->fh_size + sizeof(hash) > fh_maxsize)
 		goto out_no_space;
 
 	hash = cpu_to_le64(siphash(&fh->fh_raw, fh->fh_size, fh_key));
@@ -167,7 +166,7 @@ static bool fh_append_mac(struct svc_fh *fhp, struct net *net)
 
 out_no_space:
 	pr_warn_ratelimited("NFSD: unable to sign filehandles, fh_size %zu would be greater than fh_maxsize %d.\n",
-			    fh->fh_size + sizeof(hash), fhp->fh_maxsize);
+			    fh->fh_size + sizeof(hash), fh_maxsize);
 	return false;
 }
 
@@ -566,7 +565,8 @@ static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
 		fhp->fh_handle.fh_size += maxsize * 4;
 
 		if (exp->ex_flags & NFSEXP_SIGN_FH)
-			if (!fh_append_mac(fhp, exp->cd->net))
+			if (!fh_append_mac(&fhp->fh_handle, fhp->fh_maxsize,
+					   exp->cd->net))
 				fhp->fh_handle.fh_fileid_type = FILEID_INVALID;
 	} else {
 		fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
diff --git a/fs/nfsd/nfsfh.h b/fs/nfsd/nfsfh.h
index 5ef7191f8ad8..5dc10b442d6c 100644
--- a/fs/nfsd/nfsfh.h
+++ b/fs/nfsd/nfsfh.h
@@ -226,6 +226,7 @@ __be32	fh_getattr(const struct svc_fh *fhp, struct kstat *stat);
 __be32	fh_compose(struct svc_fh *, struct svc_export *, struct dentry *, struct svc_fh *);
 __be32	fh_update(struct svc_fh *);
 void	fh_put(struct svc_fh *);
+bool	fh_append_mac(struct knfsd_fh *fh, int fh_maxsize, struct net *net);
 
 static __inline__ struct svc_fh *
 fh_copy(struct svc_fh *dst, const struct svc_fh *src)

-- 
2.54.0