NFS4: Only set creation opendata if O_CREAT

[ Upstream commit 90910519 ]

We can end up in nfs4_opendata_alloc during task exit, in which case
current->fs has already been cleaned up.  This leads to a crash in
current_umask().

Fix this by only setting creation opendata if we are actually doing an open
with O_CREAT.  We can drop the check for NULL nfs4_open_createattrs, since
O_CREAT will never be set for the recovery path.
Suggested-by: Trond Myklebust <trondmy@hammerspace.com>
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

fs/nfs/nfs4proc.c

@@ -1234,10 +1234,20 @@ static struct nfs4_opendata *nfs4_opendata_alloc(struct dentry *dentry,
 	atomic_inc(&sp->so_count);
 	p->o_arg.open_flags = flags;
 	p->o_arg.fmode = fmode & (FMODE_READ|FMODE_WRITE);
-	p->o_arg.umask = current_umask();
 	p->o_arg.claim = nfs4_map_atomic_open_claim(server, claim);
 	p->o_arg.share_access = nfs4_map_atomic_open_share(server,
 			fmode, flags);
+	if (flags & O_CREAT) {
+		p->o_arg.umask = current_umask();
+		p->o_arg.label = nfs4_label_copy(p->a_label, label);
+		if (c->sattr != NULL && c->sattr->ia_valid != 0) {
+			p->o_arg.u.attrs = &p->attrs;
+			memcpy(&p->attrs, c->sattr, sizeof(p->attrs));
+
+			memcpy(p->o_arg.u.verifier.data, c->verf,
+					sizeof(p->o_arg.u.verifier.data));
+		}
+	}
 	/* don't put an ACCESS op in OPEN compound if O_EXCL, because ACCESS
 	 * will return permission denied for all bits until close */
 	if (!(flags & O_EXCL)) {
@@ -1261,7 +1271,6 @@ static struct nfs4_opendata *nfs4_opendata_alloc(struct dentry *dentry,
 	p->o_arg.server = server;
 	p->o_arg.bitmask = nfs4_bitmask(server, label);
 	p->o_arg.open_bitmap = &nfs4_fattr_bitmap[0];
-	p->o_arg.label = nfs4_label_copy(p->a_label, label);
 	switch (p->o_arg.claim) {
 	case NFS4_OPEN_CLAIM_NULL:
 	case NFS4_OPEN_CLAIM_DELEGATE_CUR:
@@ -1274,13 +1283,6 @@ static struct nfs4_opendata *nfs4_opendata_alloc(struct dentry *dentry,
 	case NFS4_OPEN_CLAIM_DELEG_PREV_FH:
 		p->o_arg.fh = NFS_FH(d_inode(dentry));
 	}
-	if (c != NULL && c->sattr != NULL && c->sattr->ia_valid != 0) {
-		p->o_arg.u.attrs = &p->attrs;
-		memcpy(&p->attrs, c->sattr, sizeof(p->attrs));
-
-		memcpy(p->o_arg.u.verifier.data, c->verf,
-				sizeof(p->o_arg.u.verifier.data));
-	}
 	p->c_arg.fh = &p->o_res.fh;
 	p->c_arg.stateid = &p->o_res.stateid;
 	p->c_arg.seqid = p->o_arg.seqid;