!7 Fix issue of "open device vnode may cause deadlock

Merge pull request !7 from ysy4tc3/dev

fs/vfs/fs_open.c

@@ -192,8 +192,8 @@ int fp_open(char *fullpath, int oflags, mode_t mode)
         }
 #ifdef LOSCFG_FS_VFS_BLOCK_DEVICE
       if (vnode->type == VNODE_TYPE_BLK) {
-          fd = block_proxy(fullpath, oflags);
           VnodeDrop();
+          fd = block_proxy(fullpath, oflags);
           if (fd < 0)
             {
               ret = fd;