Summary locking fix (GH PR 2493)

github-pr-2493.patch

@@ -0,0 +1,72 @@
+From 2c39bd88a9b0db207c1158c76bbbe0b484dec9dd Mon Sep 17 00:00:00 2001
+From: Colin Walters <walters@verbum.org>
+Date: Fri, 3 Dec 2021 14:35:12 -0500
+Subject: [PATCH] repo: Change locking for summary regeneration to be shared
+
+This is trying to address:
+https://pagure.io/fedora-iot/issue/48
+
+Basically we changed rpm-ostree to start doing a shared lock during
+commit by default, but this broke because pungi is starting a process
+doing a commit for each architecture, and then trying to regenerate
+the summary after each one.
+
+This patch is deleting a big comment with a rationale for why
+summary regeneration should be exclusive.  Point by point:
+
+> This makes sure the commits and deltas don't get
+> deleted while generating the summary.
+
+But prune operations require an exclusive lock, which means that
+data still can't be deleted when the summary grabs a shared lock.
+
+> It also means we can be sure refs
+> won't be created/updated/deleted during the operation, without having to
+> add exclusive locks to those operations which would prevent concurrent
+> commits from working.
+
+First: The status quo *has* prevented concurrent commits from working!
+
+There is no real locking solution to this problem. What we really
+need to do here is regenerate the summary after each commit *or*
+when the caller decides to do it and e.g. include deltas at the same
+time.
+
+It's OK if multiple threads race to regenerate the summary;
+last-one-wins behavior here is totally fine.
+---
+ src/libostree/ostree-repo.c | 10 ++--------
+ 1 file changed, 2 insertions(+), 8 deletions(-)
+
+diff --git a/src/libostree/ostree-repo.c b/src/libostree/ostree-repo.c
+index 74cea37f2..a9be9f948 100644
+--- a/src/libostree/ostree-repo.c
++++ b/src/libostree/ostree-repo.c
+@@ -6105,7 +6105,7 @@ summary_add_ref_entry (OstreeRepo       *self,
+  * and refs in %OSTREE_SUMMARY_COLLECTION_MAP are guaranteed to be in
+  * lexicographic order.
+  *
+- * Locking: exclusive
++ * Locking: shared (Prior to 2021.7, this was exclusive)
+  */
+ gboolean
+ ostree_repo_regenerate_summary (OstreeRepo     *self,
+@@ -6113,16 +6113,10 @@ ostree_repo_regenerate_summary (OstreeRepo     *self,
+                                 GCancellable   *cancellable,
+                                 GError        **error)
+ {
+-  /* Take an exclusive lock. This makes sure the commits and deltas don't get
+-   * deleted while generating the summary. It also means we can be sure refs
+-   * won't be created/updated/deleted during the operation, without having to
+-   * add exclusive locks to those operations which would prevent concurrent
+-   * commits from working.
+-   */
+   g_autoptr(OstreeRepoAutoLock) lock = NULL;
+   gboolean no_deltas_in_summary = FALSE;
+ 
+-  lock = ostree_repo_auto_lock_push (self, OSTREE_REPO_LOCK_EXCLUSIVE,
++  lock = ostree_repo_auto_lock_push (self, OSTREE_REPO_LOCK_SHARED,
+                                      cancellable, error);
+   if (!lock)
+     return FALSE;
+

ostree.spec

@@ -8,11 +8,13 @@
 Summary: Tool for managing bootable, immutable filesystem trees
 Name: ostree
 Version: 2021.6
-Release: 2%{?dist}
+Release: 3%{?dist}
 Source0: https://github.com/ostreedev/%{name}/releases/download/v%{version}/libostree-%{version}.tar.xz
 License: LGPLv2+
 URL: https://ostree.readthedocs.io/en/latest/
 
+Patch1: github-pr-2493.patch
+
 BuildRequires: make
 BuildRequires: git
 # We always run autogen.sh
@@ -165,6 +167,9 @@ find %{buildroot} -name '*.la' -delete
 %endif
 
 %changelog
+* Thu Dec 09 2021 Peter Robinson <pbrobinson@fedoraproject.org> - 2021.6-3
+- Summary locking fix (GH PR 2493)
+
 * Mon Dec 06 2021 Joseph Marrero <jmarrero@fedoraproject.org> - 2021.6-2
 - Add attr as a build dependency as we use it for running the tests