NFS: Add a lookupfh NFS RPC op

Add a lookup filehandle NFS RPC op so that a file handle can be looked up
without requiring dentries and inodes and other VFS stuff when doing an NFS4
pathwalk during mounting.

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index b46597fc81e1..de2006f754ef 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1583,6 +1583,52 @@ nfs4_proc_setattr(struct dentry *dentry, struct nfs_fattr *fattr,
         return status;
 }
 
+static int _nfs4_proc_lookupfh(struct nfs_server *server, struct nfs_fh *dirfh,
+                struct qstr *name, struct nfs_fh *fhandle,
+                struct nfs_fattr *fattr)
+{
+        int                    status;
+        struct nfs4_lookup_arg args = {
+                .bitmask = server->attr_bitmask,
+                .dir_fh = dirfh,
+                .name = name,
+        };
+        struct nfs4_lookup_res res = {
+                .server = server,
+                .fattr = fattr,
+                .fh = fhandle,
+        };
+        struct rpc_message msg = {
+                .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_LOOKUP],
+                .rpc_argp = &args,
+                .rpc_resp = &res,
+        };
+
+        nfs_fattr_init(fattr);
+
+        dprintk("NFS call  lookupfh %s\n", name->name);
+        status = rpc_call_sync(server->client, &msg, 0);
+        dprintk("NFS reply lookupfh: %d\n", status);
+        if (status == -NFS4ERR_MOVED)
+                status = -EREMOTE;
+        return status;
+}
+
+static int nfs4_proc_lookupfh(struct nfs_server *server, struct nfs_fh *dirfh,
+                              struct qstr *name, struct nfs_fh *fhandle,
+                              struct nfs_fattr *fattr)
+{
+        struct nfs4_exception exception = { };
+        int err;
+        do {
+                err = nfs4_handle_exception(server,
+                                _nfs4_proc_lookupfh(server, dirfh, name,
+                                                    fhandle, fattr),
+                                &exception);
+        } while (exception.retry);
+        return err;
+}
+
 static int _nfs4_proc_lookup(struct inode *dir, struct qstr *name,
                 struct nfs_fh *fhandle, struct nfs_fattr *fattr)
 {
@@ -3723,6 +3769,7 @@ struct nfs_rpc_ops	nfs_v4_clientops = {
         .getroot        = nfs4_proc_get_root,
         .getattr        = nfs4_proc_getattr,
         .setattr        = nfs4_proc_setattr,
+        .lookupfh       = nfs4_proc_lookupfh,
         .lookup         = nfs4_proc_lookup,
         .access         = nfs4_proc_access,
         .readlink       = nfs4_proc_readlink,