From 6f0a95897cacf6edb8d753e19aedf2f4f1f12108 Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Wed, 25 Oct 2023 14:20:40 -0400
Subject: [PATCH] Revert "Fix hard linking issue causing overlay fs copy-ups"

This reverts commit 9ef0a9e8aa2e27991434c104ad73b1b95b241f08.

Master now has a better solution.
---
 src/libstore/build/local-derivation-goal.cc |  7 +++----
 src/libstore/local-fs-store.hh              | 10 ----------
 src/libstore/local-overlay-store.cc         |  8 --------
 src/libstore/local-overlay-store.hh         |  6 ------
 4 files changed, 3 insertions(+), 28 deletions(-)

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 9da3afffd..40a0385af 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -388,9 +388,8 @@ void LocalDerivationGoal::cleanupPostOutputsRegisteredModeNonCheck()
 
 
 #if __linux__
-static void linkOrCopy(LocalFSStore & store, const StorePath & from_, const Path & to)
+static void linkOrCopy(const Path & from, const Path & to)
 {
-    auto from = store.toRealPathForHardLink(from_);
     if (link(from.c_str(), to.c_str()) == -1) {
         /* Hard-linking fails if we exceed the maximum link count on a
            file (e.g. 32000 of ext3), which is quite possible after a
@@ -715,7 +714,7 @@ void LocalDerivationGoal::startBuilder()
             if (S_ISDIR(lstat(r).st_mode))
                 dirsInChroot.insert_or_assign(p, r);
             else
-                linkOrCopy(getLocalStore(), i, chrootRootDir + p);
+                linkOrCopy(r, chrootRootDir + p);
         }
 
         /* If we're repairing, checking or rebuilding part of a
@@ -1600,7 +1599,7 @@ void LocalDerivationGoal::addDependency(const StorePath & path)
                     throw Error("could not add path '%s' to sandbox", worker.store.printStorePath(path));
 
             } else
-                linkOrCopy(getLocalStore(), path, target);
+                linkOrCopy(source, target);
 
         #else
             throw Error("don't know how to make path '%s' (produced by a recursive Nix call) appear in the sandbox",
diff --git a/src/libstore/local-fs-store.hh b/src/libstore/local-fs-store.hh
index 19858f5c8..488109501 100644
--- a/src/libstore/local-fs-store.hh
+++ b/src/libstore/local-fs-store.hh
@@ -73,16 +73,6 @@ public:
         return getRealStoreDir() + "/" + std::string(storePath, storeDir.size() + 1);
     }
 
-    /**
-     * If the real path is hardlinked with something else, we might
-     * prefer to refer to the other path instead. This is the case with
-     * overlayfs, for example.
-     */
-    virtual Path toRealPathForHardLink(const StorePath & storePath)
-    {
-        return Store::toRealPath(storePath);
-    }
-
     std::optional<std::string> getBuildLogExact(const StorePath & path) override;
 
 };
diff --git a/src/libstore/local-overlay-store.cc b/src/libstore/local-overlay-store.cc
index 73902e9ba..732b4d6ce 100644
--- a/src/libstore/local-overlay-store.cc
+++ b/src/libstore/local-overlay-store.cc
@@ -268,14 +268,6 @@ std::pair<bool, StorePathSet> LocalOverlayStore::verifyAllValidPaths(RepairFlag
 }
 
 
-Path LocalOverlayStore::toRealPathForHardLink(const StorePath & path)
-{
-    return lowerStore->isValidPath(path)
-        ? lowerStore->Store::toRealPath(path)
-        : Store::toRealPath(path);
-}
-
-
 void LocalOverlayStore::remountIfNecessary()
 {
     if (!_remountRequired) return;
diff --git a/src/libstore/local-overlay-store.hh b/src/libstore/local-overlay-store.hh
index 8ed7516db..ac730c77c 100644
--- a/src/libstore/local-overlay-store.hh
+++ b/src/libstore/local-overlay-store.hh
@@ -186,12 +186,6 @@ private:
      */
     std::pair<bool, StorePathSet> verifyAllValidPaths(RepairFlag repair) override;
 
-    /**
-     * For lower-store paths, we used the lower store location. This avoids the
-     * wasteful "copying up" that would otherwise happen.
-     */
-    Path toRealPathForHardLink(const StorePath & storePath) override;
-
     /**
      * Deletion only effects the upper layer, so we ignore lower-layer referrers.
      */