From a15e8ba52bcc079f1144cd9e532064d079a5e722 Mon Sep 17 00:00:00 2001
From: Gregor Kleen <gkleen@yggdrasil.li>
Date: Fri, 11 Mar 2022 12:53:19 +0100
Subject: luksroot: bypassWorkqueues

---
 modules/luksroot.nix | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

(limited to 'modules/luksroot.nix')

diff --git a/modules/luksroot.nix b/modules/luksroot.nix
index abaee692..52de2c40 100644
--- a/modules/luksroot.nix
+++ b/modules/luksroot.nix
@@ -140,9 +140,12 @@ let
     umount /crypt-ramfs 2>/dev/null
   '';
 
-  openCommand = name': { name, device, header, keyFile, keyFileSize, keyFileOffset, allowDiscards, yubikey, gpgCard, fido2, clevis, dmi, fallbackToPassword, preOpenCommands, postOpenCommands, ... }: assert name' == name;
+  openCommand = name': { name, device, header, keyFile, keyFileSize, keyFileOffset, allowDiscards, bypassWorkqueues, yubikey, gpgCard, fido2, clevis, dmi, fallbackToPassword, preOpenCommands, postOpenCommands, ... }: assert name' == name;
   let
-    csopen   = "cryptsetup luksOpen ${device} ${name} ${optionalString allowDiscards "--allow-discards"} ${optionalString (header != null) "--header=${header}"}";
+    csopen   = "cryptsetup luksOpen ${device} ${name}"
+             + optionalString allowDiscards " --allow-discards"
+             + optionalString bypassWorkqueues " --perf-no_read_workqueue --perf-no_write_workqueue"
+             + optionalString (header != null) " --header=${header}";
     cschange = "cryptsetup luksChangeKey ${device} ${optionalString (header != null) "--header=${header}"}";
   in ''
     # Wait for luksRoot (and optionally keyFile and/or header) to appear, e.g.
@@ -658,6 +661,17 @@ in
             '';
           };
 
+          bypassWorkqueues = mkOption {
+            default = false;
+            type = types.bool;
+            description = ''
+              Whether to bypass dm-crypt's internal read and write workqueues.
+              Enabling this should improve performance on SSDs; see
+              <link xlink:href="https://wiki.archlinux.org/index.php/Dm-crypt/Specialties#Disable_workqueue_for_increased_solid_state_drive_(SSD)_performance">here</link>
+              for more information. Needs Linux 5.9 or later.
+            '';
+          };
+
           fallbackToPassword = mkOption {
             default = false;
             type = types.bool;
-- 
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