12870: Don't send invalidation for inodes still referenced by kernel

When trying to flush cached inode contents, invalidating dentries
which are still referenced can race with lookups, causing the kernel to return
spurious "not found" errors.

Arvados-DCO-1.1-Signed-off-by: Peter Amstutz <pamstutz@veritasgenetics.com>

diff --git a/services/fuse/arvados_fuse/__init__.py b/services/fuse/arvados_fuse/__init__.py
index 418f748fe1a25fe65232abd904312bf44267992d..788d475e33c0d094d719503e6b9fc4dba386e1ec 100644 (file)
--- a/services/fuse/arvados_fuse/__init__.py
+++ b/services/fuse/arvados_fuse/__init__.py
@@ -159,10 +159,11 @@ class InodeCache(object):
             if obj.in_use():
                 _logger.debug("InodeCache cannot clear inode %i, in use", obj.inode)
                 return
-            obj.kernel_invalidate()
             if obj.has_ref(True):
-                _logger.debug("InodeCache sent kernel invalidate inode %i", obj.inode)
+                _logger.debug("InodeCache cannot clear inode %i, still referenced", obj.inode)
                 return
+            obj.kernel_invalidate()
+            _logger.debug("InodeCache sent kernel invalidate inode %i", obj.inode)
             obj.clear()
 
         # The llfuse lock is released in del_entry(), which is called by