Add idmap mount support

libfuse/include/fuse_common.h

@@ -133,6 +133,7 @@ struct fuse_file_info_t
 #define FUSE_CAP_PASSTHROUGH          (1ULL << 25)
 #define FUSE_CAP_HANDLE_KILLPRIV      (1ULL << 26)
 #define FUSE_CAP_HANDLE_KILLPRIV_V2   (1ULL << 27)
+#define FUSE_CAP_ALLOW_IDMAP          (1ULL << 28)
 
 /**
  * Ioctl flags

libfuse/lib/fuse_lowlevel.cpp

@@ -1203,6 +1203,8 @@ do_init(fuse_req_t             req,
         f->conn.capable |= FUSE_CAP_HANDLE_KILLPRIV;
       if(inargflags & FUSE_HANDLE_KILLPRIV_V2)
         f->conn.capable |= FUSE_CAP_HANDLE_KILLPRIV_V2;
+      if(inargflags & FUSE_ALLOW_IDMAP)
+        f->conn.capable |= FUSE_CAP_ALLOW_IDMAP;
     }
   else
     {
@@ -1280,6 +1282,9 @@ do_init(fuse_req_t             req,
     outargflags |= FUSE_HANDLE_KILLPRIV;
   if(f->conn.want & FUSE_CAP_HANDLE_KILLPRIV_V2)
     outargflags |= FUSE_HANDLE_KILLPRIV_V2;
+  if(f->conn.want & FUSE_CAP_ALLOW_IDMAP)
+    outargflags |= FUSE_ALLOW_IDMAP;
+
   if(f->conn.want & FUSE_CAP_PASSTHROUGH)
     {
       outargflags |= FUSE_PASSTHROUGH;

src/fuse_init.cpp

@@ -206,6 +206,7 @@ FUSE::init(fuse_conn_info *conn_)
   ::_want_if_capable(conn_,FUSE_CAP_POSIX_ACL,&cfg.posix_acl);
   ::_want_if_capable(conn_,FUSE_CAP_READDIR_PLUS,&cfg.readdirplus);
   ::_want_if_capable(conn_,FUSE_CAP_WRITEBACK_CACHE,&cfg.writeback_cache);
+  ::_want_if_capable(conn_,FUSE_CAP_ALLOW_IDMAP);
   //    ::_want_if_capable(conn_,FUSE_CAP_READDIR_PLUS_AUTO);
   ::_want_if_capable_max_pages(conn_,cfg);
   conn_->want &= ~FUSE_CAP_POSIX_LOCKS;