pnfs: layoutret_on_setattr

With the objects layout security model, we have object capabilities
that are associated with the layout and we anticipate that the server
will issue a cb_layoutrecall for any setattr that changes security
related attributes (user/group/mode/acl) or truncates the file.

Therefore, the layout is returned before issuing the setattr to avoid
the anticipated cb_layoutrecall.

Signed-off-by: Benny Halevy <bhalevy@panasas.com>

fs/nfs/nfs4proc.c

@@ -2361,6 +2361,9 @@ nfs4_proc_setattr(struct dentry *dentry, struct nfs_fattr *fattr,
 	struct nfs4_state *state = NULL;
 	int status;
 
+	if (pnfs_ld_layoutret_on_setattr(inode))
+		pnfs_return_layout(inode);
+
 	nfs_fattr_init(fattr);
 	
 	/* Search for an existing open(O_WRITE) file */