From ca40aa3ca3a250f34252e8109a735a9afc8e03a2 Mon Sep 17 00:00:00 2001
From: HustonMmmavr <huston.mavr@gmail.com>
Date: Tue, 17 Dec 2019 13:25:46 +0300
Subject: [PATCH] fio: fix race condition in mktree
Despite the lack of documentation, fio.mktree() was designed to work
similar to mkdir -p: it creates the directory along with it's parents
and doesn't complain about existing ones.
But this function was subject to a race if two different processes were
trying to create the same directory at the same time. It was caused by
the fact that directory existence check and its creation aren't atomic.
This patch fixes the race by impoving error handling: it's not an error
if directory exists, even if it was created by someone else and mktree
failed.
Related to https://github.com/tarantool/doc/issues/1063
Closes #4660
(cherry picked from commit 21ae2899e7ad064fa4b2bfb7804fb4590f12c492)
---
src/lua/fio.lua | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/src/lua/fio.lua b/src/lua/fio.lua
index cb224f3d0f..4692e10266 100644
--- a/src/lua/fio.lua
+++ b/src/lua/fio.lua
@@ -364,7 +364,11 @@ fio.mktree = function(path, mode)
local stat = fio.stat(current_dir)
if stat == nil then
local st, err = fio.mkdir(current_dir, mode)
- if err ~= nil then
+ -- fio.stat() and fio.mkdir() above are separate calls
+ -- and a file system may be changed between them. So
+ -- if the error here is due to an existing directory,
+ -- the function should not report an error.
+ if err ~= nil and not fio.path.is_dir(current_dir) then
return false, string.format("Error creating directory %s: %s",
current_dir, tostring(err))
end
--
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