From: Joey Hess <joeyh@joeyh.name>
Date: Wed, 27 Oct 2021 18:55:30 +0000 (-0400)
Subject: add a comment about checkSaneLock
X-Git-Tag: archive/raspbian/10.20250416-2+rpi1~2^2^2~57^2~79
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=a3cdff3fd52de12d0dda9004ea1212001a03d45c;p=git-annex.git

add a comment about checkSaneLock

See commit 8c2dd7d8ee814614bf3c871903b5d4d2aba193f4 for original
introduction of it, but needing to spelunk that far back to understand
the code is not good.
---

diff --git a/Annex/Transfer.hs b/Annex/Transfer.hs
index 119c91b1af..315033d219 100644
--- a/Annex/Transfer.hs
+++ b/Annex/Transfer.hs
@@ -151,6 +151,11 @@ runTransfer' ignorelock t afile stalldetection retrydecider transferaction =
 		createAnnexDirectory $ P.takeDirectory lck
 		tryLockExclusive (Just mode) lck >>= \case
 			Nothing -> return (Nothing, True)
+			-- Since the lock file is removed in cleanup,
+			-- there's a race where different processes
+			-- may have a deleted and a new version of the same
+			-- lock file open. checkSaneLock guards against
+			-- that.
 			Just lockhandle -> ifM (checkSaneLock lck lockhandle)
 				( do
 					createtfile