cryptsetup: add support for workqueue options

This commit adds support for disabling the read and write
workqueues with the new crypttab options no-read-workqueue
and no-write-workqueue. These correspond to the cryptsetup
options --perf-no_read_workqueue and --perf-no_write_workqueue
respectively.

(cherry picked from commit 227acf0009bde2cd7f8bc371615b05e84137847d)

3 files changed, 39 insertions, 0 deletions

diff --git a/man/crypttab.xml b/man/crypttab.xml
index ee54499bfe..eb060c103e 100644
--- a/man/crypttab.xml
+++ b/man/crypttab.xml
@@ -273,6 +273,25 @@
       </varlistentry>
 
       <varlistentry>
+        <term><option>no-read-workqueue</option></term>
+
+        <listitem><para>Bypass dm-crypt internal workqueue and process read requests synchronously. The
+        default is to queue these requests and process them asynchronously.</para>
+
+        <para>This requires kernel 5.9 or newer.</para>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><option>no-write-workqueue</option></term>
+
+        <listitem><para>Bypass dm-crypt internal workqueue and process write requests synchronously. The
+        default is to queue these requests and process them asynchronously.</para>
+
+        <para>This requires kernel 5.9 or newer.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
         <term><option>skip=</option></term>
 
         <listitem><para>How many 512-byte sectors of the encrypted data to skip at the
diff --git a/src/cryptsetup/cryptsetup.c b/src/cryptsetup/cryptsetup.c
index 6d3f842dbe..12e32ebf05 100644
--- a/src/cryptsetup/cryptsetup.c
+++ b/src/cryptsetup/cryptsetup.c
@@ -55,6 +55,8 @@ static bool arg_verify = false;
 static bool arg_discards = false;
 static bool arg_same_cpu_crypt = false;
 static bool arg_submit_from_crypt_cpus = false;
+static bool arg_no_read_workqueue = false;
+static bool arg_no_write_workqueue = false;
 static bool arg_tcrypt_hidden = false;
 static bool arg_tcrypt_system = false;
 static bool arg_tcrypt_veracrypt = false;
@@ -218,6 +220,10 @@ static int parse_one_option(const char *option) {
                 arg_same_cpu_crypt = true;
         else if (streq(option, "submit-from-crypt-cpus"))
                 arg_submit_from_crypt_cpus = true;
+        else if (streq(option, "no-read-workqueue"))
+                arg_no_read_workqueue = true;
+        else if (streq(option, "no-write-workqueue"))
+                arg_no_write_workqueue = true;
         else if (streq(option, "luks"))
                 arg_type = ANY_LUKS;
 /* since cryptsetup 2.3.0 (Feb 2020) */
@@ -805,6 +811,12 @@ static uint32_t determine_flags(void) {
         if (arg_submit_from_crypt_cpus)
                 flags |= CRYPT_ACTIVATE_SUBMIT_FROM_CRYPT_CPUS;
 
+        if (arg_no_read_workqueue)
+                flags |= CRYPT_ACTIVATE_NO_READ_WORKQUEUE;
+
+        if (arg_no_write_workqueue)
+                flags |= CRYPT_ACTIVATE_NO_WRITE_WORKQUEUE;
+
 #ifdef CRYPT_ACTIVATE_SERIALIZE_MEMORY_HARD_PBKDF
         /* Try to decrease the risk of OOM event if memory hard key derivation function is in use */
         /* https://gitlab.com/cryptsetup/cryptsetup/issues/446/ */
diff --git a/src/shared/crypt-util.h b/src/shared/crypt-util.h
index c25b11599c..ce44cd43e7 100644
--- a/src/shared/crypt-util.h
+++ b/src/shared/crypt-util.h
@@ -6,6 +6,14 @@
 
 #include "macro.h"
 
+/* These next two are defined in libcryptsetup.h from cryptsetup version 2.3.4 forwards. */
+#ifndef CRYPT_ACTIVATE_NO_READ_WORKQUEUE
+#define CRYPT_ACTIVATE_NO_READ_WORKQUEUE (1 << 24)
+#endif
+#ifndef CRYPT_ACTIVATE_NO_WRITE_WORKQUEUE
+#define CRYPT_ACTIVATE_NO_WRITE_WORKQUEUE (1 << 25)
+#endif
+
 DEFINE_TRIVIAL_CLEANUP_FUNC(struct crypt_device *, crypt_free);
 
 void cryptsetup_log_glue(int level, const char *msg, void *usrptr);