From 6d86e355c251a68dd870e22ea1cdd43eea10c390 Mon Sep 17 00:00:00 2001
From: Tom Clegg <tom@curoverse.com>
Date: Tue, 24 Nov 2015 13:45:02 -0500
Subject: [PATCH] 7751: Fix race by telling fuse not to cache the
 .arvados#collection dirent.

---
 services/fuse/arvados_fuse/__init__.py     |  4 ++--
 services/fuse/arvados_fuse/fresh.py        |  2 ++
 services/fuse/arvados_fuse/fusefile.py     |  7 +++++++
 services/fuse/tests/test_tmp_collection.py | 19 +++++++++++--------
 4 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/services/fuse/arvados_fuse/__init__.py b/services/fuse/arvados_fuse/__init__.py
index b7c0091a61..65f117b55a 100644
--- a/services/fuse/arvados_fuse/__init__.py
+++ b/services/fuse/arvados_fuse/__init__.py
@@ -407,8 +407,8 @@ class Operations(llfuse.Operations):
         entry = llfuse.EntryAttributes()
         entry.st_ino = inode
         entry.generation = 0
-        entry.entry_timeout = 60
-        entry.attr_timeout = 60
+        entry.entry_timeout = 60 if e.allow_dirent_cache else 0
+        entry.attr_timeout = 60 if e.allow_attr_cache else 0
 
         entry.st_mode = stat.S_IRUSR | stat.S_IRGRP | stat.S_IROTH
         if isinstance(e, Directory):
diff --git a/services/fuse/arvados_fuse/fresh.py b/services/fuse/arvados_fuse/fresh.py
index ec2d47a269..2075741dbd 100644
--- a/services/fuse/arvados_fuse/fresh.py
+++ b/services/fuse/arvados_fuse/fresh.py
@@ -67,6 +67,8 @@ class FreshBase(object):
         self.cache_priority = None
         self.cache_size = 0
         self.cache_uuid = None
+        self.allow_attr_cache = True
+        self.allow_dirent_cache = True
 
     # Mark the value as stale
     def invalidate(self):
diff --git a/services/fuse/arvados_fuse/fusefile.py b/services/fuse/arvados_fuse/fusefile.py
index d4c075a40d..e731327dec 100644
--- a/services/fuse/arvados_fuse/fusefile.py
+++ b/services/fuse/arvados_fuse/fusefile.py
@@ -112,6 +112,13 @@ class FuncToJSONFile(StringFile):
         super(FuncToJSONFile, self).__init__(parent_inode, "", 0)
         self.func = func
 
+        # invalidate_inode() and invalidate_entry() are asynchronous
+        # with no callback to wait for. In order to guarantee
+        # userspace programs don't get stale data that was generated
+        # before the last invalidate(), we must disallow dirent
+        # caching entirely.
+        self.allow_dirent_cache = False
+
     def size(self):
         self._update()
         return super(FuncToJSONFile, self).size()
diff --git a/services/fuse/tests/test_tmp_collection.py b/services/fuse/tests/test_tmp_collection.py
index e403a2c4ea..60eba1bf85 100644
--- a/services/fuse/tests/test_tmp_collection.py
+++ b/services/fuse/tests/test_tmp_collection.py
@@ -110,12 +110,15 @@ class TmpCollectionTest(IntegrationTest):
              r'^\. 37b51d194a7513e45b56f6524f2d51f2\+3(\+\S+)? acbd18db4cc2f85cedef654fccc4a4d8\+3(\+\S+)? 0:3:bar 3:3:foo\n$'),
             ('foo', None,
              r'^\. 37b51d194a7513e45b56f6524f2d51f2\+3(\+\S+)? 0:3:bar\n$'),
+            ('bar', None,
+             r'^$'),
         ]
-        for fn, content, expect in ops:
-            path = os.path.join(tmpdir, fn)
-            if content is None:
-                os.unlink(path)
-            else:
-                with open(path, 'w') as f:
-                    f.write(content)
-            self.assertRegexpMatches(current_manifest(tmpdir), expect)
+        for _ in range(10):
+            for fn, content, expect in ops:
+                path = os.path.join(tmpdir, fn)
+                if content is None:
+                    os.unlink(path)
+                else:
+                    with open(path, 'w') as f:
+                        f.write(content)
+                self.assertRegexpMatches(current_manifest(tmpdir), expect)
-- 
2.30.2