NFS: Introduce NFS_ATTR_FATTR_V4_LOCATIONS

The Linux NFS client must distinguish between referral events (which
it currently supports) and migration events (which it does not yet
support).

In both types of events, an fs_locations array is returned.  But upper
layers, not the XDR layer, should make the distinction between a
referral and a migration.  There really isn't a way for an XDR decoder
function to distinguish the two, in general.

Slightly adjust the FATTR flags returned by decode_fs_locations()
to set NFS_ATTR_FATTR_V4_LOCATIONS only if a non-empty locations
array was returned from the server.  Then have logic in nfs4proc.c
distinguish whether the locations array is for a referral or
something else.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 54767dd66cf..281c2def2b1 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -79,6 +79,7 @@ static int _nfs4_proc_open(struct nfs4_opendata *data);
 static int _nfs4_recover_proc_open(struct nfs4_opendata *data);
 static int nfs4_do_fsinfo(struct nfs_server *, struct nfs_fh *, struct nfs_fsinfo *);
 static int nfs4_async_handle_error(struct rpc_task *, const struct nfs_server *, struct nfs4_state *);
+static void nfs_fixup_referral_attributes(struct nfs_fattr *fattr);
 static int _nfs4_proc_getattr(struct nfs_server *server, struct nfs_fh *fhandle, struct nfs_fattr *fattr);
 static int nfs4_do_setattr(struct inode *inode, struct rpc_cred *cred,
                             struct nfs_fattr *fattr, struct iattr *sattr,
@@ -2340,7 +2341,6 @@ static int nfs4_proc_get_root(struct nfs_server *server, struct nfs_fh *fhandle,
         return nfs4_map_errors(status);
 }
 
-static void nfs_fixup_referral_attributes(struct nfs_fattr *fattr);
 /*
  * Get locations and (maybe) other attributes of a referral.
  * Note that we'll actually follow the referral later when
@@ -4797,11 +4797,11 @@ static void nfs_fixup_referral_attributes(struct nfs_fattr *fattr)
         if (!(((fattr->valid & NFS_ATTR_FATTR_MOUNTED_ON_FILEID) ||
                (fattr->valid & NFS_ATTR_FATTR_FILEID)) &&
               (fattr->valid & NFS_ATTR_FATTR_FSID) &&
-              (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)))
+              (fattr->valid & NFS_ATTR_FATTR_V4_LOCATIONS)))
                 return;
 
         fattr->valid |= NFS_ATTR_FATTR_TYPE | NFS_ATTR_FATTR_MODE |
-                NFS_ATTR_FATTR_NLINK;
+                NFS_ATTR_FATTR_NLINK | NFS_ATTR_FATTR_V4_REFERRAL;
         fattr->mode = S_IFDIR | S_IRUGO | S_IXUGO;
         fattr->nlink = 2;
 }