From ffd8ad2d80f689d3d4503f52e0af013931ea6d1c Mon Sep 17 00:00:00 2001 From: HustonMmmavr 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 --- 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 cb224f3d0fb3..4692e102665a 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