New dracut 95nbft module

meson.build

@@ -24,10 +24,12 @@ mandir     = join_paths(prefixdir, get_option('mandir'))
 sbindir    = join_paths(prefixdir, get_option('sbindir'))
 sysconfdir = join_paths(prefixdir, get_option('sysconfdir'))
 
-udevrulesdir   = join_paths(prefixdir, get_option('udevrulesdir'))
-dracutrulesdir = join_paths(prefixdir, get_option('dracutrulesdir'))
-systemddir     = join_paths(prefixdir, get_option('systemddir'))
-rundir         = join_paths(prefixdir, get_option('rundir'))
+udevrulesdir      = join_paths(prefixdir, get_option('udevrulesdir'))
+dracutrulesdir    = join_paths(prefixdir, get_option('dracutrulesdir'))
+dracutmodulesdir  = join_paths(prefixdir, get_option('dracutmodulesdir'))
+systemddir        = join_paths(prefixdir, get_option('systemddir'))
+rundir            = join_paths(prefixdir, get_option('rundir'))
+networkmanagerdir = join_paths(prefixdir, get_option('networkmanagerdir'))
 
 ###############################################################################
 conf = configuration_data()
@@ -199,14 +201,16 @@ substs.set('NAME',    meson.project_name())
 substs.set('VERSION', meson.project_version())
 substs.set('LICENSE', meson.project_license()[0])
 substs.set('UDEVRULESDIR', udevrulesdir)
-substs.set('DRACUTRILESDIR', dracutrulesdir)
+substs.set('DRACUTRULESDIR', dracutrulesdir)
+substs.set('DRACUTMODULESDIR', dracutmodulesdir)
 substs.set('REQUIRES', requires)
 substs.set('DATADIR', datadir)
 substs.set('MANDIR', mandir)
 substs.set('RUNDIR', rundir)
 substs.set('SBINDIR', sbindir)
 substs.set('SYSCONFDIR', sysconfdir)
 substs.set('SYSTEMDDIR', systemddir)
+substs.set('NETWORKMANAGERDIR', networkmanagerdir)
 substs.set('SYSTEMCTL', get_option('systemctl'))
 
 configure_file(
@@ -221,18 +225,59 @@ disc = configure_file(
   configuration: substs,
 )
 
-dracut_files = [
+dracut_conf_files = [
   '70-nvmf-autoconnect.conf',
 ]
 
-foreach file : dracut_files
+foreach file : dracut_conf_files
   configure_file(
     input: 'nvmf-autoconnect/dracut-conf/' + file + '.in',
     output: file,
     configuration: substs,
   )
 endforeach
 
+want_dracut_module = get_option('dracut-module')
+if want_dracut_module
+  dracut_nbft_files = [
+    'module-setup.sh',
+    'nbft-boot-pre.service',
+    'nbft-boot-connect.service'
+  ]
+
+  foreach file : dracut_nbft_files
+    configure_file(
+      input: 'nvmf-autoconnect/dracut-95nbft/' + file + '.in',
+      output: file,
+      configuration: substs,
+    )
+  endforeach
+
+  networkmanager_conf_files = [
+    '99-nvme-nbft-no-ignore-carrier.conf'
+  ]
+
+  foreach file : networkmanager_conf_files
+    configure_file(
+      input: 'nvmf-autoconnect/NetworkManager/' + file + '.in',
+      output: file,
+      configuration: substs,
+    )
+  endforeach
+
+  networkmanager_dispatcher_files = [
+    '99-nvme-nbft-connect.sh'
+  ]
+
+  foreach file : networkmanager_dispatcher_files
+    configure_file(
+      input: 'nvmf-autoconnect/NetworkManager/' + file + '.in',
+      output: file,
+      configuration: substs,
+    )
+  endforeach
+endif
+
 systemd_files = [
   'nvmefc-boot-connections.service',
   'nvmf-autoconnect.service',
@@ -315,11 +360,28 @@ install_data('completions/bash-nvme-completion.sh',
 install_data('completions/_nvme',
              install_dir: datadir + '/zsh/site-functions')
 
-foreach file : dracut_files
+foreach file : dracut_conf_files
   install_data(meson.current_build_dir() + '/' + file,
                install_dir: dracutrulesdir)
 endforeach
 
+if want_dracut_module
+  foreach file : dracut_nbft_files
+    install_data(meson.current_build_dir() + '/' + file,
+                 install_dir: dracutmodulesdir + '95nbft/')
+  endforeach
+
+  foreach file : networkmanager_conf_files
+    install_data(meson.current_build_dir() + '/' + file,
+                 install_dir: networkmanagerdir + 'conf.d/')
+  endforeach
+
+  foreach file : networkmanager_dispatcher_files
+    install_data(meson.current_build_dir() + '/' + file,
+                 install_dir: networkmanagerdir + 'dispatcher.d/')
+  endforeach
+endif
+
 foreach file : systemd_files
   install_data(meson.current_build_dir() + '/' + file,
                install_dir: systemddir)
@@ -343,8 +405,10 @@ if meson.version().version_compare('>=0.53.0')
         'mandir':            mandir,
         'udevrulesdir':      udevrulesdir,
         'dracutrulesdir':    dracutrulesdir,
+        'dracutmodulesdir':  dracutmodulesdir,
         'rundir':            rundir,
         'systemddir':        systemddir,
+        'networkmanagerdir': networkmanagerdir,
         'build location':    meson.current_build_dir(),
     }
     summary(path_dict, section: 'Paths')
@@ -353,8 +417,9 @@ if meson.version().version_compare('>=0.53.0')
     }
     summary(dep_dict, section: 'Dependencies')
     conf_dict = {
-        'git version':       conf.get('GIT_VERSION'),
-        'pdc enabled':       get_option('pdc-enabled'),
+        'git version':           conf.get('GIT_VERSION'),
+        'pdc enabled':           get_option('pdc-enabled'),
+        'dracut module enabled': want_dracut_module
     }
     summary(conf_dict, section: 'Configuration')
 endif

meson_options.txt

@@ -17,6 +17,12 @@ option(
   value : 'lib/dracut/dracut.conf.d/',
   description : 'directory for dracut rules files'
 )
+option(
+  'dracutmodulesdir',
+  type : 'string',
+  value : 'lib/dracut/modules.d/',
+  description : 'dracut modules directory'
+)
 option(
   'htmldir',
   type : 'string',
@@ -70,3 +76,15 @@ option(
   type : 'string',
   description : 'override the git version string'
 )
+option(
+  'dracut-module',
+  type : 'boolean',
+  value : false,
+  description : 'Enable the 95nbft dracut module'
+)
+option(
+  'networkmanagerdir',
+  type : 'string',
+  value : 'lib/NetworkManager/',
+  description : 'NetworkManager lib directory'
+)

nvme.spec.in

@@ -33,7 +33,7 @@ touch %{buildroot}@SYSCONFDIR@/nvme/hostid
 @UDEVRULESDIR@/65-persistent-net-nbft.rules
 @UDEVRULESDIR@/70-nvmf-autoconnect.rules
 @UDEVRULESDIR@/71-nvmf-netapp.rules
-@DRACUTRILESDIR@/70-nvmf-autoconnect.conf
+@DRACUTRULESDIR@/70-nvmf-autoconnect.conf
 @SYSTEMDDIR@/[email protected]
 @SYSTEMDDIR@/nvmefc-boot-connections.service
 @SYSTEMDDIR@/nvmf-connect-nbft.service

nvmf-autoconnect/NetworkManager/99-nvme-nbft-connect.sh.in

@@ -0,0 +1,5 @@
+#!/bin/bash
+
+if [[ "$1" == nbft* ]] && [[ "$2" == "up" ]]; then
+    systemctl start nvmf-connect-nbft.service
+fi

nvmf-autoconnect/NetworkManager/99-nvme-nbft-no-ignore-carrier.conf.in

@@ -0,0 +1,15 @@
+# Boot from NVMe over TCP (NBFT)
+#
+# For NVMe/TCP connections that provide namespaces containing rootfs
+# it is crucial to react on carrier events and reconnect any missing
+# NVMe/TCP connections as defined in the ACPI NBFT table. A custom
+# /usr/lib/NetworkManager/dispatcher.d/99-nvme-nbft-connect.sh hook
+# will respawn nvmf-connect-nbft.service on such occasion.
+
+[device-nbft-no-ignore-carrier]
+
+# only affects nbft0, nbft1, ... interfaces
+match-device=interface-name:nbft*
+
+# react on link up/down events
+ignore-carrier=no

nvmf-autoconnect/dracut-95nbft/README.md

@@ -0,0 +1,125 @@
+# The dracut 95nbft module
+
+Focused solely on providing the Boot from NVMe over TCP functionality, intended
+to replace parts of the existing `95nvmf` dracut module. At the moment this all
+depends on the recently added NetworkManager NBFT support, though the desire is
+to support more network management frameworks in the future.
+
+Related nvme-cli meson configure options:
+* `-Ddracut-module` (default=false) - enables the 95nbft dracut module
+* `-Ddracutmodulesdir` (default=`$prefix/lib/dracut/modules.d/`)
+* `-Dnetworkmanagerdir` (default=`$prefix/lib/NetworkManager/`)
+
+
+# The design
+
+(see [dracut.bootup(7)](https://man7.org/linux/man-pages/man7/dracut.bootup.7.html)
+for the overall boot process flow)
+
+The boot process looks roughly as follows:
+* `nbft-boot-pre.service` is run, creates udev network link files and tells
+  dracut to activate networking
+* dracut runs `nm-initrd-generator` and starts the NetworkManager daemon
+* `systemd-udev-trigger.service` renames the network interfaces
+* `nm-wait-online-initrd.service` finishes, indicating networking is up and ready
+* `nbft-boot-connect.service` initiates actual NVMe connections
+* the dracut initqueue is waiting for specific block devices (rootfs) to appear
+
+Two major packages are responsible for this: the new nvme-cli dracut module and
+the added NBFT support in NetworkManager.
+
+## The new dracut 95nbft module
+
+The dracut `module-setup.sh` only installs two systemd unit files sandwiched
+between specific dracut phases, nothing else. By default the module is always
+included in the initramfs unless _hostonly_ is requested in which case the system
+is tested for ACPI NBFT tables presence and the module is only included in such
+a case.
+
+The systemd unit files are only run when the ACPI NBFT tables are present and
+no `rd.nvmf.nonbft` kernel commandline argument was provided that otherwise
+instruct the boot process to skip the NBFT machinery.
+
+## nbft-boot-pre.service
+
+Calls the nvme-cli nbft plugin to generate network link files for each interface
+found in all NBFT tables. The interface naming in form of `nbftXhY` consists
+of an ACPI NBFT table index (defaults to 0) and the specified HFI index.
+In a typical scenario only `nbft0h1`, `nbft0h2`, `nbft1h1`, ... interfaces are
+present, however it's up to the pre-OS driver to supply arbitrary indexes,
+possibly leading to interface names skipping the order to something like
+`nbft0h100` and `nbft99h123`. Comparing to the old `95nvmf` dracut module
+ordering, this new naming scheme is geared towards (semi-)stable predictable
+network interface names. Keep in mind that the contents of the NBFT tables
+is generated from scratch upon every system start and is not always persistent
+between reboots.
+
+The network link files are then picked up by udev on trigger via
+`systemd-udev-trigger.service` to apply the new interface names.
+
+For simplicity and for the time being this systemd unit replaces the traditional
+dracut cmdline hook and adds the `rd.neednet=1` `cmdline.d` argument.
+
+## nm-initrd-generator NBFT support
+
+https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/2077
+
+Executed before the NetworkManager daemon starts the added NBFT support parses
+the ACPI NBFT tables available and generates system connections. Only
+referenced by MAC addresses, relying on udev to perform actual interface
+renaming.
+
+The `nm-initrd-generator` doesn't link to `libnvme.so.1` but opens it through
+`dlopen()` in runtime. This allows for smaller hostonly initramfs images in case
+the NBFT tables are not present in the system. The library is being pulled in
+indirectly through the dracut module's requirement of nvme-cli. The
+`rd.nvmf.nonbft` kernel commandline argument is respected as well.
+
+## nbft-boot-connect.service
+
+Modprobes required modules (`nvme-fabrics`) first.
+
+Performs actual NVMe connections by calling `nvme connect-all --nbft`. The
+nvme-cli code has been modified to return non-zero return code in case one
+or more SSNS records fail to connect (except those marked as _'unavailable'_
+by the pre-OS driver), resulting in the service startup failure with defined
+respawn of 10 seconds (TBD). This ensures multiple connection attempts while
+NetworkManager reacts on link events in the background and the dracut initqueue
+eagerly waits for new block devices to appears, to be scanned and mounted. Once
+the required block device appears, the wait cycle is ended and the system
+continues booting, stopping any queued `nbft-boot-connect.service` respawns
+seamlessly.
+
+The difference from the old dracut `95nvmf` module is that the nvme connection
+attempts are not driven by network link up events but have fixed respawn
+interval. This may potentially help the cases where the NIC is slow to
+initialize, reports link up yet it takes another 5+ seconds before it's fully
+able to send/receive packets. We've seen this issue with some 25Gb NICs.
+
+
+# The post-switchroot boot flow
+
+## nvmf-connect-nbft.service
+
+This unit is supposed to run once the `network-online.target` has been reached
+and calls `nvme connect-all --nbft` again. This ensures additional connection
+attempt for records that failed to connect in the initramfs phase. As long as
+this call matches existing connections and skips SSNS records that have been
+already connected, in an ideal case this would result in an no-op. This is
+mostly a one-shot service run in NetworkManager based distros since the target
+typically stays reached until reboot.
+
+## NetworkManager dispatcher hooks
+
+The nvme-cli package installs a custom NetworkManager dispatcher service hook
+(`99-nvme-nbft-connect.sh`) that just restarts `nvmf-connect-nbft.service` on
+_link up_ events on `nbft*` interfaces. At the time the hook runs the interface
+in question has been fully configured by NetworkManager. This ensures further
+reconnection attempts in multipath scenarios where a network interface just came
+alive. This is designed as a secondary measure with the kernel nvme host driver
+connection recovery being the primary mechanism.
+
+In order to make link events work properly the `nbft*` interfaces need to be set
+not to ignore carrier events. This is done through a custom override snippet
+(`99-nvme-nbft-no-ignore-carrier.conf`) as some distributions may opt to follow
+legacy server networking behaviour (see the `NetworkManager-config-server` package).

nvmf-autoconnect/dracut-95nbft/module-setup.sh.in

@@ -0,0 +1,49 @@
+#!/usr/bin/bash
+
+has_nbft() {
+    local f found=
+    for f in /sys/firmware/acpi/tables/NBFT*; do
+        [ -f "$f" ] || continue
+        found=1
+        break
+    done
+    [[ $found ]]
+}
+
+# called by dracut
+check() {
+    require_binaries nvme || return 1
+
+    [[ $hostonly ]] || [[ $mount_needs ]] && {
+        if ! has_nbft; then
+            echo "No ACPI NBFT tables present in the system"
+            return 255
+        fi
+    }
+    return 0
+}
+
+# called by dracut
+depends() {
+    echo bash rootfs-block network
+    return 0
+}
+
+# called by dracut
+installkernel() {
+    hostonly="" instmods nvme_tcp nvme_fabrics 8021q
+}
+
+# called by dracut
+install() {
+    inst_multiple nvme
+
+    # TODO: /etc/nvme/hostnqn
+
+    for i in \
+        nbft-boot-pre.service \
+        nbft-boot-connect.service; do
+        inst_simple "${moddir}/$i" "${systemdsystemunitdir}/$i"
+        $SYSTEMCTL -q --root "$initdir" enable $i
+    done
+}