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From fff80c5a2aba519d1c58a1bfc7c0fa96b1e4c30c Mon Sep 17 00:00:00 2001
From: Lukas Nykryn <lnykryn@redhat.com>
Date: Wed, 19 Nov 2014 12:17:19 +0100
Subject: [PATCH] Revert "readahead: wipe out readahead"

This reverts commit d6bc8348d5be8576a475ac8ced2b0146e60fb71f.

Conflicts:
	units/systemd-firstboot.service.in

Conflicts:
	man/sd-daemon.xml
	man/sd-login.xml
	man/systemd-notify.xml
	src/notify/notify.c
---
 Makefile-man.am                                 |  31 ++
 Makefile.am                                     |  54 +-
 configure.ac                                    |   9 +
 man/sd-daemon.xml                               |   1 +
 man/sd-login.xml                                |   1 +
 man/sd-readahead.xml                            | 117 +++++
 man/sd_readahead.xml                            | 178 +++++++
 man/systemd-notify.xml                          |  11 +
 man/systemd-readahead-replay.service.xml        | 203 ++++++++
 po/POTFILES.skip                                |   1 +
 shell-completion/zsh/_systemd                   |   3 +-
 src/cryptsetup/cryptsetup-generator.c           |   2 +-
 src/gpt-auto-generator/gpt-auto-generator.c     |   1 +
 src/notify/notify.c                             |  20 +-
 src/readahead/Makefile                          |   1 +
 src/readahead/readahead-analyze.c               | 146 ++++++
 src/readahead/readahead-collect.c               | 650 ++++++++++++++++++++++++
 src/readahead/readahead-common.c                | 398 +++++++++++++++
 src/readahead/readahead-common.h                |  61 +++
 src/readahead/readahead-replay.c                | 281 ++++++++++
 src/readahead/readahead.c                       | 163 ++++++
 src/readahead/sd-readahead.c                    |  89 ++++
 src/readahead/test-ssd.c                        |  41 ++
 src/systemd/sd-readahead.h                      |  73 +++
 system-preset/90-systemd.preset                 |   1 +
 units/.gitignore                                |   3 +
 units/ldconfig.service                          |   2 +-
 units/quotaon.service.in                        |   2 +-
 units/system-update.target                      |   2 +-
 units/systemd-backlight@.service.in             |   2 +-
 units/systemd-binfmt.service.in                 |   2 +-
 units/systemd-firstboot.service.in              |   2 +-
 units/systemd-fsck-root.service.in              |   1 +
 units/systemd-fsck@.service.in                  |   2 +-
 units/systemd-hwdb-update.service.in            |   2 +-
 units/systemd-journal-catalog-update.service.in |   2 +-
 units/systemd-modules-load.service.in           |   1 +
 units/systemd-quotacheck.service.in             |   2 +-
 units/systemd-random-seed.service.in            |   2 +-
 units/systemd-readahead-collect.service.in      |  28 +
 units/systemd-readahead-done.service.in         |  22 +
 units/systemd-readahead-done.timer              |  22 +
 units/systemd-readahead-drop.service            |  19 +
 units/systemd-readahead-replay.service.in       |  26 +
 units/systemd-remount-fs.service.in             |   2 +-
 units/systemd-rfkill@.service.in                |   2 +-
 units/systemd-sysctl.service.in                 |   1 +
 units/systemd-sysusers.service.in               |   2 +-
 units/systemd-tmpfiles-clean.service.in         |   2 +-
 units/systemd-tmpfiles-setup-dev.service.in     |   2 +-
 units/systemd-tmpfiles-setup.service.in         |   2 +-
 units/systemd-update-done.service.in            |   2 +-
 units/systemd-update-utmp.service.in            |   2 +-
 units/systemd-vconsole-setup.service.in         |   1 +
 54 files changed, 2675 insertions(+), 23 deletions(-)
 create mode 100644 man/sd-readahead.xml
 create mode 100644 man/sd_readahead.xml
 create mode 100644 man/systemd-readahead-replay.service.xml
 create mode 120000 src/readahead/Makefile
 create mode 100644 src/readahead/readahead-analyze.c
 create mode 100644 src/readahead/readahead-collect.c
 create mode 100644 src/readahead/readahead-common.c
 create mode 100644 src/readahead/readahead-common.h
 create mode 100644 src/readahead/readahead-replay.c
 create mode 100644 src/readahead/readahead.c
 create mode 100644 src/readahead/sd-readahead.c
 create mode 100644 src/readahead/test-ssd.c
 create mode 100644 src/systemd/sd-readahead.h
 create mode 100644 units/systemd-readahead-collect.service.in
 create mode 100644 units/systemd-readahead-done.service.in
 create mode 100644 units/systemd-readahead-done.timer
 create mode 100644 units/systemd-readahead-drop.service
 create mode 100644 units/systemd-readahead-replay.service.in

diff --git a/Makefile-man.am b/Makefile-man.am
index d0fb9aa..ac6f69a 100644
--- a/Makefile-man.am
+++ b/Makefile-man.am
@@ -1234,6 +1234,34 @@ man/systemd-random-seed.html: man/systemd-random-seed.service.html
 
 endif
 
+if ENABLE_READAHEAD
+MANPAGES += \
+	man/sd-readahead.3 \
+	man/sd_readahead.3 \
+	man/systemd-readahead-replay.service.8
+MANPAGES_ALIAS += \
+	man/systemd-readahead-collect.service.8 \
+	man/systemd-readahead-done.service.8 \
+	man/systemd-readahead-done.timer.8 \
+	man/systemd-readahead.8
+man/systemd-readahead-collect.service.8: man/systemd-readahead-replay.service.8
+man/systemd-readahead-done.service.8: man/systemd-readahead-replay.service.8
+man/systemd-readahead-done.timer.8: man/systemd-readahead-replay.service.8
+man/systemd-readahead.8: man/systemd-readahead-replay.service.8
+man/systemd-readahead-collect.service.html: man/systemd-readahead-replay.service.html
+	$(html-alias)
+
+man/systemd-readahead-done.service.html: man/systemd-readahead-replay.service.html
+	$(html-alias)
+
+man/systemd-readahead-done.timer.html: man/systemd-readahead-replay.service.html
+	$(html-alias)
+
+man/systemd-readahead.html: man/systemd-readahead-replay.service.html
+	$(html-alias)
+
+endif
+
 if ENABLE_RESOLVED
 MANPAGES += \
 	man/resolved.conf.5 \
@@ -1660,6 +1688,7 @@ EXTRA_DIST += \
 	man/sd-id128.xml \
 	man/sd-journal.xml \
 	man/sd-login.xml \
+	man/sd-readahead.xml \
 	man/sd_booted.xml \
 	man/sd_bus_creds_get_pid.xml \
 	man/sd_bus_creds_new_from_pid.xml \
@@ -1707,6 +1736,7 @@ EXTRA_DIST += \
 	man/sd_machine_get_class.xml \
 	man/sd_notify.xml \
 	man/sd_pid_get_session.xml \
+	man/sd_readahead.xml \
 	man/sd_seat_get_active.xml \
 	man/sd_session_is_active.xml \
 	man/sd_uid_get_state.xml \
@@ -1766,6 +1796,7 @@ EXTRA_DIST += \
 	man/systemd-path.xml \
 	man/systemd-quotacheck.service.xml \
 	man/systemd-random-seed.service.xml \
+	man/systemd-readahead-replay.service.xml \
 	man/systemd-remount-fs.service.xml \
 	man/systemd-resolved.service.xml \
 	man/systemd-rfkill@.service.xml \
diff --git a/Makefile.am b/Makefile.am
index 70e4fbc..b0e4b5a 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -2603,7 +2603,8 @@ systemctl_LDADD = \
 
 # ------------------------------------------------------------------------------
 systemd_notify_SOURCES = \
-	src/notify/notify.c
+	src/notify/notify.c \
+	src/readahead/sd-readahead.c
 
 systemd_notify_LDADD = \
 	libsystemd-internal.la \
@@ -4736,6 +4737,57 @@ EXTRA_DIST += \
 	units/systemd-vconsole-setup.service.in
 
 # ------------------------------------------------------------------------------
+if ENABLE_READAHEAD
+systemd_readahead_SOURCES = \
+	src/readahead/readahead.c \
+	src/readahead/readahead-collect.c \
+	src/readahead/readahead-replay.c \
+	src/readahead/readahead-analyze.c \
+	src/readahead/readahead-common.c \
+	src/readahead/readahead-common.h
+
+systemd_readahead_LDADD = \
+	libsystemd-internal.la \
+	libudev-internal.la \
+	libsystemd-shared.la
+
+dist_doc_DATA += \
+	src/readahead/sd-readahead.c \
+	src/systemd/sd-readahead.h
+
+rootlibexec_PROGRAMS += \
+	systemd-readahead
+
+dist_systemunit_DATA += \
+	units/systemd-readahead-drop.service \
+	units/systemd-readahead-done.timer
+
+nodist_systemunit_DATA += \
+	units/systemd-readahead-collect.service \
+	units/systemd-readahead-replay.service \
+	units/systemd-readahead-done.service
+
+manual_tests += \
+	test-ssd
+
+test_ssd_SOURCES = \
+	src/readahead/test-ssd.c \
+	src/readahead/readahead-common.c \
+	src/readahead/readahead-common.h
+
+test_ssd_LDADD = \
+	libsystemd-internal.la \
+	libudev-internal.la \
+	libsystemd-shared.la
+
+endif
+
+EXTRA_DIST += \
+	units/systemd-readahead-collect.service.in \
+	units/systemd-readahead-replay.service.in \
+	units/systemd-readahead-done.service.in
+
+# ------------------------------------------------------------------------------
 if ENABLE_BOOTCHART
 systemd_bootchart_SOURCES = \
 	src/bootchart/bootchart.c \
diff --git a/configure.ac b/configure.ac
index 3f50887..f701bcf 100644
--- a/configure.ac
+++ b/configure.ac
@@ -931,6 +931,14 @@ fi
 AM_CONDITIONAL(ENABLE_VCONSOLE, [test "$have_vconsole" = "yes"])
 
 # ------------------------------------------------------------------------------
+have_readahead=no
+AC_ARG_ENABLE(readahead, AS_HELP_STRING([--disable-readahead], [disable readahead tools]))
+if test "x$enable_readahead" != "xno"; then
+        have_readahead=yes
+fi
+AM_CONDITIONAL(ENABLE_READAHEAD, [test "$have_readahead" = "yes"])
+
+# ------------------------------------------------------------------------------
 have_bootchart=no
 AC_ARG_ENABLE(bootchart, AS_HELP_STRING([--disable-bootchart], [disable bootchart tool]))
 if test "x$enable_bootchart" != "xno"; then
@@ -1474,6 +1482,7 @@ AC_MSG_RESULT([
         ELFUTILS:                ${have_elfutils}
         binfmt:                  ${have_binfmt}
         vconsole:                ${have_vconsole}
+        readahead:               ${have_readahead}
         bootchart:               ${have_bootchart}
         quotacheck:              ${have_quotacheck}
         tmpfiles:                ${have_tmpfiles}
diff --git a/man/sd-daemon.xml b/man/sd-daemon.xml
index b7ba363..b12abe2 100644
--- a/man/sd-daemon.xml
+++ b/man/sd-daemon.xml
@@ -137,6 +137,7 @@
       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
       <citerefentry project='man-pages'><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd-readahead</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
       <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
     </para>
   </refsect1>
diff --git a/man/sd-login.xml b/man/sd-login.xml
index 328f711..abcdb99 100644
--- a/man/sd-login.xml
+++ b/man/sd-login.xml
@@ -128,6 +128,7 @@
       <citerefentry><refentrytitle>sd_get_seats</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>sd_login_monitor_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd-readahead</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
       <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
     </para>
   </refsect1>
diff --git a/man/sd-readahead.xml b/man/sd-readahead.xml
new file mode 100644
index 0000000..bcc46b2
--- /dev/null
+++ b/man/sd-readahead.xml
@@ -0,0 +1,117 @@
+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+        "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<!--
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+-->
+
+<refentry id="sd-readahead" conditional='ENABLE_READAHEAD'>
+
+        <refentryinfo>
+                <title>sd-readahead</title>
+                <productname>systemd</productname>
+
+                <authorgroup>
+                        <author>
+                                <contrib>Developer</contrib>
+                                <firstname>Lennart</firstname>
+                                <surname>Poettering</surname>
+                                <email>lennart@poettering.net</email>
+                        </author>
+                </authorgroup>
+        </refentryinfo>
+
+        <refmeta>
+                <refentrytitle>sd-readahead</refentrytitle>
+                <manvolnum>3</manvolnum>
+        </refmeta>
+
+        <refnamediv>
+                <refname>sd-readahead</refname>
+                <refpurpose>Reference implementation of APIs for
+                controlling boot-time read-ahead</refpurpose>
+        </refnamediv>
+
+        <refsynopsisdiv>
+                <funcsynopsis>
+                        <funcsynopsisinfo>#include "sd-readahead.h"</funcsynopsisinfo>
+                </funcsynopsis>
+        </refsynopsisdiv>
+
+        <refsect1>
+                <title>Description</title>
+
+                <para><filename>sd-readahead.c</filename> and
+                <filename>sd-readahead.h</filename> provide a
+                reference implementation for APIs for controlling boot-time
+                read-ahead, as implemented by the read-ahead subsystem
+                of the
+                <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+                init system.</para>
+
+                <para>See
+                <citerefentry><refentrytitle>sd_readahead</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+                for more information about the function
+                implemented.</para>
+        </refsect1>
+
+        <refsect1>
+                <title>Notes</title>
+
+                <para>This interface is provided by the reference
+                implementation of APIs for controlling boot-time
+                read-ahead and distributed with the systemd
+                package. The algorithms it implements are simple, and
+                can easily be reimplemented in daemons if it is
+                important to support this interface without using the
+                reference implementation. See the respective function
+                man pages for details.</para>
+
+                <para>In addition, for details about the algorithms,
+                check the liberally licensed reference implementation
+                sources:
+                <ulink url="http://cgit.freedesktop.org/systemd/systemd/plain/src/readahead/sd-readahead.c"/>
+                and <ulink url="http://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-readahead.h"/></para>
+
+                <para>These APIs are implemented in the reference
+                implementation's drop-in
+                <filename>sd-readahead.c</filename> and
+                <filename>sd-readahead.h</filename> files. It is
+                recommended that applications consuming these APIs copy
+                the implementation into their source tree, either
+                verbatim or in excerpts. These interfaces are
+                currently not available in a dynamic library.</para>
+
+                <para>The functions provided by this interface become
+                NOPs when -DDISABLE_SYSTEMD is set during
+                compilation. In addition, if
+                <filename>sd-readhead.c</filename> is compiled on
+                non-Linux systems it becomes NOPs.</para>
+        </refsect1>
+
+        <refsect1>
+                <title>See Also</title>
+                <para>
+                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>sd_readahead</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+                </para>
+        </refsect1>
+
+</refentry>
diff --git a/man/sd_readahead.xml b/man/sd_readahead.xml
new file mode 100644
index 0000000..9827299
--- /dev/null
+++ b/man/sd_readahead.xml
@@ -0,0 +1,178 @@
+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+        "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<!--
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+-->
+
+<refentry id="sd_readahead" conditional='ENABLE_READAHEAD'>
+
+        <refentryinfo>
+                <title>sd_readahead</title>
+                <productname>systemd</productname>
+
+                <authorgroup>
+                        <author>
+                                <contrib>Developer</contrib>
+                                <firstname>Lennart</firstname>
+                                <surname>Poettering</surname>
+                                <email>lennart@poettering.net</email>
+                        </author>
+                </authorgroup>
+        </refentryinfo>
+
+        <refmeta>
+                <refentrytitle>sd_readahead</refentrytitle>
+                <manvolnum>3</manvolnum>
+        </refmeta>
+
+        <refnamediv>
+                <refname>sd_readahead</refname>
+                <refpurpose>Control ongoing disk boot-time read-ahead operations</refpurpose>
+        </refnamediv>
+
+        <refsynopsisdiv>
+                <funcsynopsis>
+                        <funcsynopsisinfo>#include "sd-readahead.h"</funcsynopsisinfo>
+
+                        <funcprototype>
+                                <funcdef>int <function>sd_readahead</function></funcdef>
+                                <paramdef>const char *<parameter>action</parameter></paramdef>
+                        </funcprototype>
+                </funcsynopsis>
+        </refsynopsisdiv>
+
+        <refsect1>
+                <title>Description</title>
+                <para><function>sd_readahead()</function> may be
+                called by programs involved with early boot-up to
+                control ongoing boot-time disk read-ahead operations. It may be
+                used to terminate read-ahead operations in case an
+                uncommon disk access pattern is to be expected and
+                hence read-ahead replay or collection is unlikely to
+                have the desired speed-up effect on the current or
+                future boot-ups.</para>
+
+                <para>The <parameter>action</parameter> should be one
+                of the following strings:</para>
+
+                <variablelist>
+                        <varlistentry>
+                                <term>cancel</term>
+
+                                <listitem><para>Terminates read-ahead
+                                data collection, and drops all
+                                read-ahead data collected during this
+                                boot-up.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term>done</term>
+
+                                <listitem><para>Terminates read-ahead
+                                data collection, but keeps all
+                                read-ahead data collected during this
+                                boot-up around for use during
+                                subsequent boot-ups.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term>noreplay</term>
+
+                                <listitem><para>Terminates read-ahead
+                                replay.</para></listitem>
+                        </varlistentry>
+
+                </variablelist>
+
+        </refsect1>
+
+        <refsect1>
+                <title>Return Value</title>
+
+                <para>On failure, these calls return a negative
+                errno-style error code. It is generally recommended to
+                ignore the return value of this call.</para>
+        </refsect1>
+
+        <refsect1>
+                <title>Notes</title>
+
+                <para>This function is provided by the reference
+                implementation of APIs for controlling boot-time
+                read-ahead and distributed with the systemd
+                package. The algorithm it implements is simple, and
+                can easily be reimplemented in daemons if it is
+                important to support this interface without using the
+                reference implementation.</para>
+
+                <para>Internally, this function creates a file in
+                <filename>/run/systemd/readahead/</filename> which is
+                then used as flag file to notify the read-ahead
+                subsystem.</para>
+
+                <para>For details about the algorithm check the
+                liberally licensed reference implementation sources:
+                <ulink url="http://cgit.freedesktop.org/systemd/systemd/plain/src/readahead/sd-readahead.c"/>
+                and <ulink
+                url="http://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-readahead.h"/></para>
+
+                <para><function>sd_readahead()</function> is
+                implemented in the reference implementation's drop-in
+                <filename>sd-readahead.c</filename> and
+                <filename>sd-readahead.h</filename> files. It is
+                recommended that applications consuming this API copy
+                the implementation into their source tree. For more
+                details about the reference implementation, see
+                <citerefentry><refentrytitle>sd-readahead</refentrytitle><manvolnum>3</manvolnum></citerefentry></para>
+
+                <para>If -DDISABLE_SYSTEMD is set during compilation,
+                this function will always return 0 and otherwise
+                become a NOP.</para>
+        </refsect1>
+
+        <refsect1>
+                <title>Examples</title>
+
+                <example>
+                        <title>Cancelling all read-ahead operations</title>
+
+                        <para>During boots where SELinux has to
+                        relabel the file system hierarchy, it will
+                        create a large amount of disk accesses that
+                        are not necessary during normal boots. Hence
+                        it is a good idea to disable both read-ahead replay and read-ahead collection.
+                        </para>
+
+                        <programlisting>sd_readahead("cancel");
+sd_readahead("noreplay");</programlisting>
+                </example>
+
+        </refsect1>
+
+        <refsect1>
+                <title>See Also</title>
+                <para>
+                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>sd-readahead</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+                </para>
+        </refsect1>
+
+</refentry>
diff --git a/man/systemd-notify.xml b/man/systemd-notify.xml
index 06d5ae5..46ede1a 100644
--- a/man/systemd-notify.xml
+++ b/man/systemd-notify.xml
@@ -127,6 +127,17 @@
         <citerefentry><refentrytitle>sd_booted</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><option>--readahead=</option></term>
+
+        <listitem><para>Controls disk
+        read-ahead operations. The argument
+        must be a string, and either "cancel",
+        "done" or "noreplay". For details
+        about the semantics of this option see
+        <citerefentry><refentrytitle>sd_readahead</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
+       </varlistentry>
+
       <xi:include href="standard-options.xml" xpointer="help" />
       <xi:include href="standard-options.xml" xpointer="version" />
     </variablelist>
diff --git a/man/systemd-readahead-replay.service.xml b/man/systemd-readahead-replay.service.xml
new file mode 100644
index 0000000..669fe78
--- /dev/null
+++ b/man/systemd-readahead-replay.service.xml
@@ -0,0 +1,203 @@
+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+        "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<!--
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+-->
+
+<refentry id="systemd-readahead-replay.service" conditional='ENABLE_READAHEAD'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
+
+        <refentryinfo>
+                <title>systemd-readahead-replay.service</title>
+                <productname>systemd</productname>
+
+                <authorgroup>
+                        <author>
+                                <contrib>Developer</contrib>
+                                <firstname>Lennart</firstname>
+                                <surname>Poettering</surname>
+                                <email>lennart@poettering.net</email>
+                        </author>
+                </authorgroup>
+        </refentryinfo>
+
+        <refmeta>
+                <refentrytitle>systemd-readahead-replay.service</refentrytitle>
+                <manvolnum>8</manvolnum>
+        </refmeta>
+
+        <refnamediv>
+                <refname>systemd-readahead-replay.service</refname>
+                <refname>systemd-readahead-collect.service</refname>
+                <refname>systemd-readahead-done.service</refname>
+                <refname>systemd-readahead-done.timer</refname>
+                <refname>systemd-readahead</refname>
+                <refpurpose>Disk read ahead logic</refpurpose>
+        </refnamediv>
+
+        <refsynopsisdiv>
+                <para><filename>systemd-readahead-replay.service</filename></para>
+                <para><filename>systemd-readahead-collect.service</filename></para>
+                <para><filename>systemd-readahead-done.service</filename></para>
+                <para><filename>systemd-readahead-done.timer</filename></para>
+                <cmdsynopsis>
+                        <command>/usr/lib/systemd/systemd-readahead/systemd-readahead</command>
+                        <arg choice="opt" rep="repeat">OPTIONS</arg>
+                        <arg choice="plain">COMMAND</arg>
+                        <arg choice="opt">DIRECTORY | FILE</arg>
+                </cmdsynopsis>
+        </refsynopsisdiv>
+
+        <refsect1>
+                <title>Description</title>
+
+                <para><filename>systemd-readahead-collect.service</filename>
+                is a service that collects disk usage patterns at boot
+                time. <filename>systemd-readahead-replay.service</filename>
+                is a service that replays this access data collected
+                at the subsequent boot. Since disks tend to be
+                magnitudes slower than RAM, this is intended to improve
+                boot speeds by pre-loading early at boot all data on
+                disk that is known to be read for the complete boot
+                process.</para>
+
+                <para><filename>systemd-readahead-done.service</filename>
+                is executed a short while after boot completed and signals
+                <filename>systemd-readahead-collect.service</filename>
+                to end data collection. On this signal, this service
+                will then sort the collected disk accesses and store
+                information about them in
+                <filename>/.readahead</filename>.</para>
+
+                <para>Normally, both
+                <filename>systemd-readahead-collect.service</filename>
+                and
+                <filename>systemd-readahead-replay.service</filename>
+                are activated at boot so that access patterns from the
+                preceding boot are replayed and new data collected
+                for the subsequent boot. However, on read-only media
+                where the collected data cannot be stored, it might
+                be a good idea to disable
+                <filename>systemd-readahead-collect.service</filename>.</para>
+
+                <para>On rotating media, when replaying disk accesses
+                at early boot,
+                <filename>systemd-readahead-replay.service</filename>
+                will order read requests by their location on disk. On
+                non-rotating media, they will be ordered by their
+                original access timestamp. If the file system supports
+                it,
+                <filename>systemd-readahead-collect.service</filename>
+                will also defragment and rearrange files on disk to
+                optimize subsequent boot times.</para>
+        </refsect1>
+
+        <refsect1>
+                <title>Options</title>
+
+                <para><filename>systemd-readahead</filename> understands
+                the following options:</para>
+
+                <variablelist>
+                        <varlistentry>
+                                <term><option>--files-max=</option></term>
+
+                                <listitem><para>Maximum number of
+                                files to read ahead. Only valid
+                                for thes <command>collect</command>
+                                command.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><option>--file-size-max=</option></term>
+
+                                <listitem><para>Maximum size of files
+                                in bytes to read ahead. Only valid
+                                for the <command>collect</command>
+                                and <command>replay</command>
+                                commands.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><option>--timeout=</option></term>
+
+                                <listitem><para>Maximum time in microseconds
+                                to spend collecting data. Only valid
+                                for the <command>collect</command>
+                                command.</para></listitem>
+                        </varlistentry>
+
+                        <xi:include href="standard-options.xml" xpointer="help" />
+                        <xi:include href="standard-options.xml" xpointer="version" />
+                </variablelist>
+
+        </refsect1>
+
+        <refsect1>
+                <title>Commands</title>
+
+                <para>The following commands are understood by
+                <filename>systemd-readahead</filename>:</para> <variablelist>
+                        <varlistentry>
+                                <term><command>collect
+                                [<replaceable>DIRECTORY</replaceable>]</command></term>
+                                <listitem>
+                                        <para>Collect read-ahead data on
+                                        early boot. When terminating, it will
+                                        write out a pack file to the indicated
+                                        directory containing the read-ahead
+                                        data. </para>
+                                </listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><command>replay
+                                [<replaceable>DIRECTORY</replaceable>]</command></term>
+                                <listitem>
+                                        <para>Perform read-ahead on the
+                                        specified directory tree.</para>
+                                </listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><command>analyze
+                                [<replaceable>FILE</replaceable>]</command></term>
+                                <listitem>
+                                        <para>Dumps the content of the
+                                        read-ahead pack file to the
+                                        terminal. For each file, the
+                                        output lists approximately how
+                                        much will be read ahead by
+                                        the <command>replay</command>
+                                        command.</para>
+                                </listitem>
+                        </varlistentry>
+
+                </variablelist>
+        </refsect1>
+
+        <refsect1>
+                <title>See Also</title>
+                <para>
+                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+                </para>
+        </refsect1>
+
+</refentry>
diff --git a/po/POTFILES.skip b/po/POTFILES.skip
index 51254ec..b552029 100644
--- a/po/POTFILES.skip
+++ b/po/POTFILES.skip
@@ -17,5 +17,6 @@ src/hostname/hostnamed.c
 src/locale/localed.c
 src/core/org.freedesktop.systemd1.policy.in
 src/timedate/timedated.c
+units/systemd-readahead-done.service.in
 units/user@.service.in
 units/debug-shell.service.in
diff --git a/shell-completion/zsh/_systemd b/shell-completion/zsh/_systemd
index 58b1c7b..06f03bd 100644
--- a/shell-completion/zsh/_systemd
+++ b/shell-completion/zsh/_systemd
@@ -63,7 +63,8 @@ case "$service" in
             '--ready[Inform the init system about service start-up completion.]' \
             '--pid=[Inform the init system about the main PID of the daemon]' \
             '--status=[Send a free-form status string for the daemon to the init systemd]' \
-            '--booted[Returns 0 if the system was booted up with systemd]'
+            '--booted[Returns 0 if the system was booted up with systemd]' \
+            '--readahead=[Controls disk read-ahead operations]:arguments:(cancel done noreply)'
     ;;
     systemd-tty-ask-password-agent)
         _arguments \
diff --git a/src/cryptsetup/cryptsetup-generator.c b/src/cryptsetup/cryptsetup-generator.c
index 05061c0..dfbca87 100644
--- a/src/cryptsetup/cryptsetup-generator.c
+++ b/src/cryptsetup/cryptsetup-generator.c
@@ -111,7 +111,7 @@ static int create_disk(
                 "Conflicts=umount.target\n"
                 "BindsTo=dev-mapper-%i.device\n"
                 "IgnoreOnIsolate=true\n"
-                "After=cryptsetup-pre.target\n",
+                "After=systemd-readahead-collect.service systemd-readahead-replay.service cryptsetup-pre.target\n",
                 f);
 
         if (!nofail)
diff --git a/src/gpt-auto-generator/gpt-auto-generator.c b/src/gpt-auto-generator/gpt-auto-generator.c
index 5c58b58..7d5a6c6 100644
--- a/src/gpt-auto-generator/gpt-auto-generator.c
+++ b/src/gpt-auto-generator/gpt-auto-generator.c
@@ -133,6 +133,7 @@ static int add_cryptsetup(const char *id, const char *what, bool rw, char **devi
                 "Before=umount.target cryptsetup.target\n"
                 "After=%s\n"
                 "IgnoreOnIsolate=true\n"
+                "After=systemd-readahead-collect.service systemd-readahead-replay.service\n\n"
                 "[Service]\n"
                 "Type=oneshot\n"
                 "RemainAfterExit=yes\n"
diff --git a/src/notify/notify.c b/src/notify/notify.c
index f98075d..e4a128b 100644
--- a/src/notify/notify.c
+++ b/src/notify/notify.c
@@ -31,6 +31,7 @@
 #include "strv.h"
 #include "util.h"
 #include "log.h"
+#include "sd-readahead.h"
 #include "build.h"
 #include "env-util.h"
 
@@ -38,6 +39,7 @@ static bool arg_ready = false;
 static pid_t arg_pid = 0;
 static const char *arg_status = NULL;
 static bool arg_booted = false;
+static const char *arg_readahead = NULL;
 
 static void help(void) {
         printf("%s [OPTIONS...] [VARIABLE=VALUE...]\n\n"
@@ -48,6 +50,7 @@ static void help(void) {
                "     --pid[=PID]       Set main pid of daemon\n"
                "     --status=TEXT     Set status text\n"
                "     --booted          Check if the system was booted up with systemd\n",
+               "     --readahead=ACTION Controls read-ahead operations\n",
                program_invocation_short_name);
 }
 
@@ -59,6 +62,7 @@ static int parse_argv(int argc, char *argv[]) {
                 ARG_PID,
                 ARG_STATUS,
                 ARG_BOOTED,
+                ARG_READAHEAD
         };
 
         static const struct option options[] = {
@@ -68,6 +72,7 @@ static int parse_argv(int argc, char *argv[]) {
                 { "pid",       optional_argument, NULL, ARG_PID       },
                 { "status",    required_argument, NULL, ARG_STATUS    },
                 { "booted",    no_argument,       NULL, ARG_BOOTED    },
+                { "readahead", required_argument, NULL, ARG_READAHEAD },
                 {}
         };
 
@@ -113,6 +118,10 @@ static int parse_argv(int argc, char *argv[]) {
                         arg_booted = true;
                         break;
 
+                case ARG_READAHEAD:
+                        arg_readahead = optarg;
+                        break;
+
                 case '?':
                         return -EINVAL;
 
@@ -125,7 +134,8 @@ static int parse_argv(int argc, char *argv[]) {
             !arg_ready &&
             !arg_status &&
             !arg_pid &&
-            !arg_booted) {
+            !arg_booted &&
+            !arg_readahead) {
                 help();
                 return -EINVAL;
         }
@@ -150,6 +160,14 @@ int main(int argc, char* argv[]) {
         if (arg_booted)
                 return sd_booted() <= 0;
 
+        if (arg_readahead) {
+                r = sd_readahead(arg_readahead);
+                if (r < 0) {
+                        log_error("Failed to issue read-ahead control command: %s", strerror(-r));
+                        goto finish;
+                }
+        }
+
         if (arg_ready)
                 our_env[i++] = (char*) "READY=1";
 
diff --git a/src/readahead/Makefile b/src/readahead/Makefile
new file mode 120000
index 0000000..d0b0e8e
--- /dev/null
+++ b/src/readahead/Makefile
@@ -0,0 +1 @@
+../Makefile
\ No newline at end of file
diff --git a/src/readahead/readahead-analyze.c b/src/readahead/readahead-analyze.c
new file mode 100644
index 0000000..76db3cb
--- /dev/null
+++ b/src/readahead/readahead-analyze.c
@@ -0,0 +1,146 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2012 Auke Kok <auke-jan.h.kok@intel.com>
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include <inttypes.h>
+#include <linux/limits.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <string.h>
+
+#include "readahead-common.h"
+
+int main_analyze(const char *pack_path) {
+        char line[LINE_MAX];
+        _cleanup_fclose_ FILE *pack = NULL;
+        int a;
+        int missing = 0;
+        size_t tsize = 0;
+
+        if (!pack_path)
+                pack_path = "/.readahead";
+
+        pack = fopen(pack_path, "re");
+        if (!pack) {
+                log_error("Pack file missing.");
+                goto fail;
+        }
+
+        if (!fgets(line, sizeof(line), pack)) {
+                log_error("Pack file corrupt.");
+                goto fail;
+        }
+
+        char_array_0(line);
+
+        if (!endswith(line, READAHEAD_PACK_FILE_VERSION)) {
+                log_error("Pack file version incompatible with this parser.");
+                goto fail;
+        }
+
+        if ((a = getc(pack)) == EOF) {
+                log_error("Pack file corrupt.");
+                goto fail;
+        }
+
+        fputs("   pct  sections     size: path\n"
+              "   ===  ========     ====: ====\n", stdout);
+
+        for (;;) {
+                char path[PATH_MAX];
+                struct stat st;
+                uint64_t inode;
+                int pages = 0;
+                int sections = 0;
+
+                if (!fgets(path, sizeof(path), pack))
+                        break; /* done */
+
+                path[strlen(path)-1] = 0;
+
+                if (fread(&inode, sizeof(inode), 1, pack) != 1) {
+                        log_error("Pack file corrupt.");
+                        goto fail;
+                }
+
+                for (;;) {
+                        uint32_t b, c;
+
+                        if (fread(&b, sizeof(b), 1, pack) != 1  ||
+                            fread(&c, sizeof(c), 1, pack) != 1) {
+                                log_error("Pack file corrupt.");
+                                goto fail;
+                        }
+                        if ((b == 0) && (c == 0))
+                                break;
+
+                        /* Uncomment this to get all the chunks separately
+                           printf(" %d: %d %d\n", sections, b, c);
+                         */
+
+                        pages += (c - b);
+                        sections++;
+                }
+
+                if (stat(path, &st) == 0) {
+                        off_t size;
+
+                        if (sections == 0)
+                                size = st.st_size;
+                        else
+                                size = pages * page_size();
+
+                        tsize += size;
+
+                        printf("  %4jd%% (%2d) %12jd: %s\n",
+                               (intmax_t) (sections && st.st_size ? size * 100 / st.st_size : 100),
+                               sections ? sections : 1,
+                               (intmax_t) size,
+                               path);
+                } else {
+                        printf("  %4dp (%2d) %12s: %s (MISSING)\n",
+                                sections ? pages : -1,
+                                sections ? sections : 1,
+                                "???",
+                                path);
+                        missing++;
+                }
+
+        }
+
+        printf("\nHOST:    %s"
+               "TYPE:    %c\n"
+               "MISSING: %d\n"
+               "TOTAL:   %zu\n",
+               line,
+               a,
+               missing,
+               tsize);
+
+        return EXIT_SUCCESS;
+
+fail:
+        return EXIT_FAILURE;
+}
diff --git a/src/readahead/readahead-collect.c b/src/readahead/readahead-collect.c
new file mode 100644
index 0000000..822a803
--- /dev/null
+++ b/src/readahead/readahead-collect.c
@@ -0,0 +1,650 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <inttypes.h>
+#include <fcntl.h>
+#include <linux/limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/select.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <linux/fanotify.h>
+#include <sys/signalfd.h>
+#include <sys/poll.h>
+#include <sys/mman.h>
+#include <linux/fs.h>
+#include <linux/fiemap.h>
+#include <sys/ioctl.h>
+#include <sys/vfs.h>
+#include <getopt.h>
+#include <sys/inotify.h>
+#include <math.h>
+
+#ifdef HAVE_LINUX_BTRFS_H
+#include <linux/btrfs.h>
+#endif
+
+#ifdef HAVE_FANOTIFY_INIT
+#include <sys/fanotify.h>
+#endif
+
+#include "systemd/sd-daemon.h"
+
+#include "missing.h"
+#include "util.h"
+#include "set.h"
+#include "ioprio.h"
+#include "readahead-common.h"
+#include "virt.h"
+
+/* fixme:
+ *
+ * - detect ssd on btrfs/lvm...
+ * - read ahead directories
+ * - gzip?
+ * - remount rw?
+ * - handle files where nothing is in mincore
+ * - does ioprio_set work with fadvise()?
+ */
+
+static ReadaheadShared *shared = NULL;
+static usec_t starttime;
+
+/* Avoid collisions with the NULL pointer */
+#define SECTOR_TO_PTR(s) ULONG_TO_PTR((s)+1)
+#define PTR_TO_SECTOR(p) (PTR_TO_ULONG(p)-1)
+
+static int btrfs_defrag(int fd) {
+        struct btrfs_ioctl_vol_args data = { .fd = fd };
+
+        return ioctl(fd, BTRFS_IOC_DEFRAG, &data);
+}
+
+static int pack_file(FILE *pack, const char *fn, bool on_btrfs) {
+        struct stat st;
+        void *start = MAP_FAILED;
+        uint8_t *vec;
+        uint32_t b, c;
+        uint64_t inode;
+        size_t l, pages;
+        bool mapped;
+        int r = 0, fd = -1, k;
+
+        assert(pack);
+        assert(fn);
+
+        fd = open(fn, O_RDONLY|O_CLOEXEC|O_NOATIME|O_NOCTTY|O_NOFOLLOW);
+        if (fd < 0) {
+
+                if (errno == ENOENT)
+                        return 0;
+
+                if (errno == EPERM || errno == EACCES)
+                        return 0;
+
+                log_warning("open(%s) failed: %m", fn);
+                r = -errno;
+                goto finish;
+        }
+
+        k = file_verify(fd, fn, arg_file_size_max, &st);
+        if (k <= 0) {
+                r = k;
+                goto finish;
+        }
+
+        if (on_btrfs)
+                btrfs_defrag(fd);
+
+        l = PAGE_ALIGN(st.st_size);
+        start = mmap(NULL, l, PROT_READ, MAP_SHARED, fd, 0);
+        if (start == MAP_FAILED) {
+                log_warning("mmap(%s) failed: %m", fn);
+                r = -errno;
+                goto finish;
+        }
+
+        pages = l / page_size();
+        vec = alloca0(pages);
+        if (mincore(start, l, vec) < 0) {
+                log_warning("mincore(%s) failed: %m", fn);
+                r = -errno;
+                goto finish;
+        }
+
+        fputs(fn, pack);
+        fputc('\n', pack);
+
+        /* Store the inode, so that we notice when the file is deleted */
+        inode = (uint64_t) st.st_ino;
+        fwrite(&inode, sizeof(inode), 1, pack);
+
+        mapped = false;
+        for (c = 0; c < pages; c++) {
+                bool new_mapped = !!(vec[c] & 1);
+
+                if (!mapped && new_mapped)
+                        b = c;
+                else if (mapped && !new_mapped) {
+                        fwrite(&b, sizeof(b), 1, pack);
+                        fwrite(&c, sizeof(c), 1, pack);
+
+                        log_debug("%s: page %u to %u", fn, b, c);
+                }
+
+                mapped = new_mapped;
+        }
+
+        /* We don't write any range data if we should read the entire file */
+        if (mapped && b > 0) {
+                fwrite(&b, sizeof(b), 1, pack);
+                fwrite(&c, sizeof(c), 1, pack);
+
+                log_debug("%s: page %u to %u", fn, b, c);
+        }
+
+        /* End marker */
+        b = 0;
+        fwrite(&b, sizeof(b), 1, pack);
+        fwrite(&b, sizeof(b), 1, pack);
+
+finish:
+        if (start != MAP_FAILED)
+                munmap(start, l);
+
+        safe_close(fd);
+
+        return r;
+}
+
+static unsigned long fd_first_block(int fd) {
+        struct {
+                struct fiemap fiemap;
+                struct fiemap_extent extent;
+        } data = {
+                .fiemap.fm_length = ~0ULL,
+                .fiemap.fm_extent_count = 1,
+        };
+
+        if (ioctl(fd, FS_IOC_FIEMAP, &data) < 0)
+                return 0;
+
+        if (data.fiemap.fm_mapped_extents <= 0)
+                return 0;
+
+        if (data.fiemap.fm_extents[0].fe_flags & FIEMAP_EXTENT_UNKNOWN)
+                return 0;
+
+        return (unsigned long) data.fiemap.fm_extents[0].fe_physical;
+}
+
+struct item {
+        const char *path;
+        unsigned long block;
+        unsigned long bin;
+};
+
+static int qsort_compare(const void *a, const void *b) {
+        const struct item *i, *j;
+
+        i = a;
+        j = b;
+
+        /* sort by bin first */
+        if (i->bin < j->bin)
+                return -1;
+        if (i->bin > j->bin)
+                return 1;
+
+        /* then sort by sector */
+        if (i->block < j->block)
+                return -1;
+        if (i->block > j->block)
+                return 1;
+
+        return strcmp(i->path, j->path);
+}
+
+static int collect(const char *root) {
+        enum {
+                FD_FANOTIFY,  /* Get the actual fs events */
+                FD_SIGNAL,
+                FD_INOTIFY,   /* We get notifications to quit early via this fd */
+                _FD_MAX
+        };
+        struct pollfd pollfd[_FD_MAX] = {};
+        int fanotify_fd = -1, signal_fd = -1, inotify_fd = -1, r = 0;
+        pid_t my_pid;
+        Hashmap *files = NULL;
+        Iterator i;
+        char *p, *q;
+        sigset_t mask;
+        FILE *pack = NULL;
+        char *pack_fn_new = NULL, *pack_fn = NULL;
+        bool on_ssd, on_btrfs;
+        struct statfs sfs;
+        usec_t not_after;
+        uint64_t previous_block_readahead;
+        bool previous_block_readahead_set = false;
+
+        assert(root);
+
+        if (asprintf(&pack_fn, "%s/.readahead", root) < 0) {
+                r = log_oom();
+                goto finish;
+        }
+
+        starttime = now(CLOCK_MONOTONIC);
+
+        /* If there's no pack file yet we lower the kernel readahead
+         * so that mincore() is accurate. If there is a pack file
+         * already we assume it is accurate enough so that kernel
+         * readahead is never triggered. */
+        previous_block_readahead_set =
+                access(pack_fn, F_OK) < 0 &&
+                block_get_readahead(root, &previous_block_readahead) >= 0 &&
+                block_set_readahead(root, 8*1024) >= 0;
+
+        if (ioprio_set(IOPRIO_WHO_PROCESS, getpid(), IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0)) < 0)
+                log_warning("Failed to set IDLE IO priority class: %m");
+
+        assert_se(sigemptyset(&mask) == 0);
+        sigset_add_many(&mask, SIGINT, SIGTERM, -1);
+        assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
+
+        if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
+                log_error("signalfd(): %m");
+                r = -errno;
+                goto finish;
+        }
+
+        files = hashmap_new(&string_hash_ops);
+        if (!files) {
+                log_error("Failed to allocate set.");
+                r = -ENOMEM;
+                goto finish;
+        }
+
+        fanotify_fd = fanotify_init(FAN_CLOEXEC|FAN_NONBLOCK, O_RDONLY|O_LARGEFILE|O_CLOEXEC|O_NOATIME);
+        if (fanotify_fd < 0)  {
+                log_error("Failed to create fanotify object: %m");
+                r = -errno;
+                goto finish;
+        }
+
+        if (fanotify_mark(fanotify_fd, FAN_MARK_ADD|FAN_MARK_MOUNT, FAN_OPEN, AT_FDCWD, root) < 0) {
+                log_error("Failed to mark %s: %m", root);
+                r = -errno;
+                goto finish;
+        }
+
+        inotify_fd = open_inotify();
+        if (inotify_fd < 0) {
+                r = inotify_fd;
+                goto finish;
+        }
+
+        not_after = now(CLOCK_MONOTONIC) + arg_timeout;
+
+        my_pid = getpid();
+
+        pollfd[FD_FANOTIFY].fd = fanotify_fd;
+        pollfd[FD_FANOTIFY].events = POLLIN;
+        pollfd[FD_SIGNAL].fd = signal_fd;
+        pollfd[FD_SIGNAL].events = POLLIN;
+        pollfd[FD_INOTIFY].fd = inotify_fd;
+        pollfd[FD_INOTIFY].events = POLLIN;
+
+        sd_notify(0,
+                  "READY=1\n"
+                  "STATUS=Collecting readahead data");
+
+        log_debug("Collecting...");
+
+        if (access("/run/systemd/readahead/cancel", F_OK) >= 0) {
+                log_debug("Collection canceled");
+                r = -ECANCELED;
+                goto finish;
+        }
+
+        if (access("/run/systemd/readahead/done", F_OK) >= 0) {
+                log_debug("Got termination request");
+                goto done;
+        }
+
+        for (;;) {
+                union {
+                        struct fanotify_event_metadata metadata;
+                        char buffer[4096];
+                } data;
+                ssize_t n;
+                struct fanotify_event_metadata *m;
+                usec_t t;
+                int h;
+
+                if (hashmap_size(files) > arg_files_max) {
+                        log_debug("Reached maximum number of read ahead files, ending collection.");
+                        break;
+                }
+
+                t = now(CLOCK_MONOTONIC);
+                if (t >= not_after) {
+                        log_debug("Reached maximum collection time, ending collection.");
+                        break;
+                }
+
+                if ((h = poll(pollfd, _FD_MAX, (int) ((not_after - t) / USEC_PER_MSEC))) < 0) {
+
+                        if (errno == EINTR)
+                                continue;
+
+                        log_error("poll(): %m");
+                        r = -errno;
+                        goto finish;
+                }
+
+                if (h == 0) {
+                        log_debug("Reached maximum collection time, ending collection.");
+                        break;
+                }
+
+                if (pollfd[FD_SIGNAL].revents) {
+                        log_debug("Got signal.");
+                        break;
+                }
+
+                if (pollfd[FD_INOTIFY].revents) {
+                        uint8_t inotify_buffer[sizeof(struct inotify_event) + FILENAME_MAX];
+                        struct inotify_event *e;
+
+                        if ((n = read(inotify_fd, &inotify_buffer, sizeof(inotify_buffer))) < 0) {
+                                if (errno == EINTR || errno == EAGAIN)
+                                        continue;
+
+                                log_error("Failed to read inotify event: %m");
+                                r = -errno;
+                                goto finish;
+                        }
+
+                        e = (struct inotify_event*) inotify_buffer;
+                        while (n > 0) {
+                                size_t step;
+
+                                if ((e->mask & IN_CREATE) && streq(e->name, "cancel")) {
+                                        log_debug("Collection canceled");
+                                        r = -ECANCELED;
+                                        goto finish;
+                                }
+
+                                if ((e->mask & IN_CREATE) && streq(e->name, "done")) {
+                                        log_debug("Got termination request");
+                                        goto done;
+                                }
+
+                                step = sizeof(struct inotify_event) + e->len;
+                                assert(step <= (size_t) n);
+
+                                e = (struct inotify_event*) ((uint8_t*) e + step);
+                                n -= step;
+                        }
+                }
+
+                n = read(fanotify_fd, &data, sizeof(data));
+                if (n < 0) {
+
+                        if (errno == EINTR || errno == EAGAIN)
+                                continue;
+
+                        /* fanotify sometimes returns EACCES on read()
+                         * where it shouldn't. For now let's just
+                         * ignore it here (which is safe), but
+                         * eventually this should be
+                         * dropped when the kernel is fixed.
+                         *
+                         * https://bugzilla.redhat.com/show_bug.cgi?id=707577 */
+                        if (errno == EACCES)
+                                continue;
+
+                        log_error("Failed to read event: %m");
+                        r = -errno;
+                        goto finish;
+                }
+
+                for (m = &data.metadata; FAN_EVENT_OK(m, n); m = FAN_EVENT_NEXT(m, n)) {
+                        char fn[sizeof("/proc/self/fd/") + DECIMAL_STR_MAX(int)];
+                        int k;
+
+                        if (m->fd < 0)
+                                goto next_iteration;
+
+                        if (m->pid == my_pid)
+                                goto next_iteration;
+
+                        __sync_synchronize();
+                        if (m->pid == shared->replay)
+                                goto next_iteration;
+
+                        snprintf(fn, sizeof(fn), "/proc/self/fd/%i", m->fd);
+                        k = readlink_malloc(fn, &p);
+                        if (k >= 0) {
+                                if (startswith(p, "/tmp") ||
+                                    endswith(p, " (deleted)") ||
+                                    hashmap_get(files, p))
+                                        /* Not interesting, or
+                                         * already read */
+                                        free(p);
+                                else {
+                                        unsigned long ul;
+                                        usec_t entrytime;
+                                        struct item *entry;
+
+                                        entry = new0(struct item, 1);
+                                        if (!entry) {
+                                                r = log_oom();
+                                                goto finish;
+                                        }
+
+                                        ul = fd_first_block(m->fd);
+
+                                        entrytime = now(CLOCK_MONOTONIC);
+
+                                        entry->block = ul;
+                                        entry->path = strdup(p);
+                                        if (!entry->path) {
+                                                free(entry);
+                                                r = log_oom();
+                                                goto finish;
+                                        }
+                                        entry->bin = (entrytime - starttime) / 2000000;
+
+                                        k = hashmap_put(files, p, entry);
+                                        if (k < 0) {
+                                                log_warning("hashmap_put() failed: %s", strerror(-k));
+                                                free(p);
+                                        }
+                                }
+
+                        } else
+                                log_warning("readlink(%s) failed: %s", fn, strerror(-k));
+
+                next_iteration:
+                        safe_close(m->fd);
+                }
+        }
+
+done:
+        fanotify_fd = safe_close(fanotify_fd);
+
+        log_debug("Writing Pack File...");
+
+        on_ssd = fs_on_ssd(root) > 0;
+        log_debug("On SSD: %s", yes_no(on_ssd));
+
+        on_btrfs = statfs(root, &sfs) >= 0 && F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC);
+        log_debug("On btrfs: %s", yes_no(on_btrfs));
+
+        if (asprintf(&pack_fn_new, "%s/.readahead.new", root) < 0) {
+                r = log_oom();
+                goto finish;
+        }
+
+        pack = fopen(pack_fn_new, "we");
+        if (!pack) {
+                log_error("Failed to open pack file: %m");
+                r = -errno;
+                goto finish;
+        }
+
+        fputs(CANONICAL_HOST READAHEAD_PACK_FILE_VERSION, pack);
+        putc(on_ssd ? 'S' : 'R', pack);
+
+        if (on_ssd || on_btrfs) {
+
+                /* On SSD or on btrfs, just write things out in the
+                 * order the files were accessed. */
+
+                HASHMAP_FOREACH_KEY(q, p, files, i)
+                        pack_file(pack, p, on_btrfs);
+        } else {
+                unsigned n;
+
+                /* On rotating media, order things by the block
+                 * numbers */
+
+                log_debug("Ordering...");
+
+                n = hashmap_size(files);
+                if (n) {
+                        _cleanup_free_ struct item *ordered;
+                        struct item *j;
+                        unsigned k;
+
+                        ordered = new(struct item, n);
+                        if (!ordered) {
+                                r = log_oom();
+                                goto finish;
+                        }
+
+                        j = ordered;
+                        HASHMAP_FOREACH_KEY(q, p, files, i) {
+                                memcpy(j, q, sizeof(struct item));
+                                j++;
+                        }
+
+                        assert(ordered + n == j);
+
+                        qsort(ordered, n, sizeof(struct item), qsort_compare);
+
+                        for (k = 0; k < n; k++)
+                                pack_file(pack, ordered[k].path, on_btrfs);
+                } else
+                        log_warning("No pack files");
+        }
+
+        log_debug("Finalizing...");
+
+        fflush(pack);
+
+        if (ferror(pack)) {
+                log_error("Failed to write pack file.");
+                r = -EIO;
+                goto finish;
+        }
+
+        if (rename(pack_fn_new, pack_fn) < 0) {
+                log_error("Failed to rename readahead file: %m");
+                r = -errno;
+                goto finish;
+        }
+
+        fclose(pack);
+        pack = NULL;
+
+        log_debug("Done.");
+
+finish:
+        safe_close(fanotify_fd);
+        safe_close(signal_fd);
+        safe_close(inotify_fd);
+
+        if (pack) {
+                fclose(pack);
+                unlink(pack_fn_new);
+        }
+        free(pack_fn_new);
+        free(pack_fn);
+
+        while ((p = hashmap_steal_first_key(files)))
+                free(p);
+
+        hashmap_free(files);
+
+        if (previous_block_readahead_set) {
+                uint64_t bytes;
+
+                /* Restore the original kernel readahead setting if we
+                 * changed it, and nobody has overwritten it since
+                 * yet. */
+                if (block_get_readahead(root, &bytes) >= 0 && bytes == 8*1024)
+                        block_set_readahead(root, previous_block_readahead);
+        }
+
+        return r;
+}
+
+int main_collect(const char *root) {
+
+        if (!root)
+                root = "/";
+
+        /* Skip this step on read-only media. Note that we check the
+         * underlying block device here, not he read-only flag of the
+         * file system on top, since that one is most likely mounted
+         * read-only anyway at boot, even if the underlying block
+         * device is theoretically writable. */
+        if (fs_on_read_only(root) > 0) {
+                log_info("Disabling readahead collector due to read-only media.");
+                return EXIT_SUCCESS;
+        }
+
+        if (!enough_ram()) {
+                log_info("Disabling readahead collector due to low memory.");
+                return EXIT_SUCCESS;
+        }
+
+        shared = shared_get();
+        if (!shared)
+                return EXIT_FAILURE;
+
+        shared->collect = getpid();
+        __sync_synchronize();
+
+        if (collect(root) < 0)
+                return EXIT_FAILURE;
+
+        return EXIT_SUCCESS;
+}
diff --git a/src/readahead/readahead-common.c b/src/readahead/readahead-common.c
new file mode 100644
index 0000000..3ca48a7
--- /dev/null
+++ b/src/readahead/readahead-common.c
@@ -0,0 +1,398 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/sysinfo.h>
+#include <sys/inotify.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include "log.h"
+#include "readahead-common.h"
+#include "util.h"
+#include "missing.h"
+#include "fileio.h"
+#include "libudev.h"
+#include "udev-util.h"
+
+int file_verify(int fd, const char *fn, off_t file_size_max, struct stat *st) {
+        assert(fd >= 0);
+        assert(fn);
+        assert(st);
+
+        if (fstat(fd, st) < 0) {
+                log_warning("fstat(%s) failed: %m", fn);
+                return -errno;
+        }
+
+        if (!S_ISREG(st->st_mode)) {
+                log_debug("Not preloading special file %s", fn);
+                return 0;
+        }
+
+        if (st->st_size <= 0 || st->st_size > file_size_max) {
+                assert_cc(sizeof(st->st_size) == 8);
+                log_debug("Not preloading file %s with size out of bounds %"PRIu64,
+                          fn, st->st_size);
+                return 0;
+        }
+
+        return 1;
+}
+
+int fs_on_ssd(const char *p) {
+        struct stat st;
+        _cleanup_udev_unref_ struct udev *udev = NULL;
+        _cleanup_udev_device_unref_ struct udev_device *udev_device = NULL;
+        struct udev_device *look_at = NULL;
+        const char *devtype, *rotational, *model, *id;
+        int r;
+
+        assert(p);
+
+        if (stat(p, &st) < 0)
+                return -errno;
+
+        if (major(st.st_dev) == 0) {
+                _cleanup_fclose_ FILE *f = NULL;
+                int mount_id;
+                union file_handle_union h = { .handle.handle_bytes = MAX_HANDLE_SZ, };
+
+                /* Might be btrfs, which exposes "ssd" as mount flag if it is on ssd.
+                 *
+                 * We first determine the mount ID here, if we can,
+                 * and then lookup the mount ID in mountinfo to find
+                 * the mount options. */
+
+                r = name_to_handle_at(AT_FDCWD, p, &h.handle, &mount_id, AT_SYMLINK_FOLLOW);
+                if (r < 0)
+                        return false;
+
+                f = fopen("/proc/self/mountinfo", "re");
+                if (!f)
+                        return false;
+
+                for (;;) {
+                        char line[LINE_MAX], *e;
+                        _cleanup_free_ char *opts = NULL;
+                        int mid;
+
+                        if (!fgets(line, sizeof(line), f))
+                                return false;
+
+                        truncate_nl(line);
+
+                        if (sscanf(line, "%i", &mid) != 1)
+                                continue;
+
+                        if (mid != mount_id)
+                                continue;
+
+                        e = strstr(line, " - ");
+                        if (!e)
+                                continue;
+
+                        if (sscanf(e+3, "%*s %*s %ms", &opts) != 1)
+                                continue;
+
+                        if (streq(opts, "ssd") || startswith(opts, "ssd,") || endswith(opts, ",ssd") || strstr(opts, ",ssd,"))
+                                return true;
+                }
+
+                return false;
+        }
+
+        udev = udev_new();
+        if (!udev)
+                return -ENOMEM;
+
+        udev_device = udev_device_new_from_devnum(udev, 'b', st.st_dev);
+        if (!udev_device)
+                return false;
+
+        devtype = udev_device_get_property_value(udev_device, "DEVTYPE");
+        if (devtype && streq(devtype, "partition"))
+                look_at = udev_device_get_parent(udev_device);
+        else
+                look_at = udev_device;
+
+        if (!look_at)
+                return false;
+
+        /* First, try high-level property */
+        id = udev_device_get_property_value(look_at, "ID_SSD");
+        if (id)
+                return streq(id, "1");
+
+        /* Second, try kernel attribute */
+        rotational = udev_device_get_sysattr_value(look_at, "queue/rotational");
+        if (rotational)
+                return streq(rotational, "0");
+
+        /* Finally, fallback to heuristics */
+        look_at = udev_device_get_parent(look_at);
+        if (!look_at)
+                return false;
+
+        model = udev_device_get_sysattr_value(look_at, "model");
+        if (model)
+                return !!strstr(model, "SSD");
+
+        return false;
+}
+
+int fs_on_read_only(const char *p) {
+        struct stat st;
+        _cleanup_udev_unref_ struct udev *udev = NULL;
+        _cleanup_udev_device_unref_ struct udev_device *udev_device = NULL;
+        const char *read_only;
+
+        assert(p);
+
+        if (stat(p, &st) < 0)
+                return -errno;
+
+        if (major(st.st_dev) == 0)
+                return false;
+
+        udev = udev_new();
+        if (!udev)
+                return -ENOMEM;
+
+        udev_device = udev_device_new_from_devnum(udev, 'b', st.st_dev);
+        if (!udev_device)
+                return false;
+
+        read_only = udev_device_get_sysattr_value(udev_device, "ro");
+        if (read_only)
+                return streq(read_only, "1");
+
+        return false;
+}
+
+bool enough_ram(void) {
+        struct sysinfo si;
+
+        assert_se(sysinfo(&si) >= 0);
+
+        /* Enable readahead only with at least 128MB memory */
+        return si.totalram > 127 * 1024*1024 / si.mem_unit;
+}
+
+static void mkdirs(void) {
+        if (mkdir("/run/systemd", 0755) && errno != EEXIST)
+                log_warning("Failed to create /run/systemd: %m");
+        if (mkdir("/run/systemd/readahead", 0755) && errno != EEXIST)
+                log_warning("Failed to create /run/systemd: %m");
+}
+
+int open_inotify(void) {
+        int fd;
+
+        fd = inotify_init1(IN_CLOEXEC|IN_NONBLOCK);
+        if (fd < 0) {
+                log_error("Failed to create inotify handle: %m");
+                return -errno;
+        }
+
+        mkdirs();
+
+        if (inotify_add_watch(fd, "/run/systemd/readahead", IN_CREATE) < 0) {
+                log_error("Failed to watch /run/systemd/readahead: %m");
+                safe_close(fd);
+                return -errno;
+        }
+
+        return fd;
+}
+
+ReadaheadShared *shared_get(void) {
+        _cleanup_close_ int fd = -1;
+        ReadaheadShared *m = NULL;
+
+        mkdirs();
+
+        fd = open("/run/systemd/readahead/shared", O_CREAT|O_RDWR|O_CLOEXEC, 0644);
+        if (fd < 0) {
+                log_error("Failed to create shared memory segment: %m");
+                return NULL;
+        }
+
+        if (ftruncate(fd, sizeof(ReadaheadShared)) < 0) {
+                log_error("Failed to truncate shared memory segment: %m");
+                return NULL;
+        }
+
+        m = mmap(NULL, sizeof(ReadaheadShared), PROT_WRITE|PROT_READ, MAP_SHARED, fd, 0);
+        if (m == MAP_FAILED) {
+                log_error("Failed to mmap shared memory segment: %m");
+                return NULL;
+        }
+
+        return m;
+}
+
+/* We use 20K instead of the more human digestable 16K here. Why?
+   Simply so that it is more unlikely that users end up picking this
+   value too so that we can recognize better whether the user changed
+   the value while we had it temporarily bumped. */
+#define BUMP_REQUEST_NR (20*1024u)
+
+int block_bump_request_nr(const char *p) {
+        struct stat st;
+        uint64_t u;
+        char *ap = NULL, *line = NULL;
+        int r;
+        dev_t d;
+
+        assert(p);
+
+        if (stat(p, &st) < 0)
+                return -errno;
+
+        if (major(st.st_dev) == 0)
+                return 0;
+
+        d = st.st_dev;
+        block_get_whole_disk(d, &d);
+
+        if (asprintf(&ap, "/sys/dev/block/%u:%u/queue/nr_requests", major(d), minor(d)) < 0) {
+                r= -ENOMEM;
+                goto finish;
+        }
+
+        r = read_one_line_file(ap, &line);
+        if (r < 0) {
+                if (r == -ENOENT)
+                        r = 0;
+                goto finish;
+        }
+
+        r = safe_atou64(line, &u);
+        if (r >= 0 && u >= BUMP_REQUEST_NR) {
+                r = 0;
+                goto finish;
+        }
+
+        free(line);
+        line = NULL;
+
+        if (asprintf(&line, "%u", BUMP_REQUEST_NR) < 0) {
+                r = -ENOMEM;
+                goto finish;
+        }
+
+        r = write_string_file(ap, line);
+        if (r < 0)
+                goto finish;
+
+        log_info("Bumped block_nr parameter of %u:%u to %u. This is a temporary hack and should be removed one day.", major(d), minor(d), BUMP_REQUEST_NR);
+        r = 1;
+
+finish:
+        free(ap);
+        free(line);
+
+        return r;
+}
+
+int block_get_readahead(const char *p, uint64_t *bytes) {
+        struct stat st;
+        char *ap = NULL, *line = NULL;
+        int r;
+        dev_t d;
+        uint64_t u;
+
+        assert(p);
+        assert(bytes);
+
+        if (stat(p, &st) < 0)
+                return -errno;
+
+        if (major(st.st_dev) == 0)
+                return 0;
+
+        d = st.st_dev;
+        block_get_whole_disk(d, &d);
+
+        if (asprintf(&ap, "/sys/dev/block/%u:%u/bdi/read_ahead_kb", major(d), minor(d)) < 0) {
+                r = -ENOMEM;
+                goto finish;
+        }
+
+        r = read_one_line_file(ap, &line);
+        if (r < 0)
+                goto finish;
+
+        r = safe_atou64(line, &u);
+        if (r < 0)
+                goto finish;
+
+        *bytes = u * 1024ULL;
+
+finish:
+        free(ap);
+        free(line);
+
+        return r;
+}
+
+int block_set_readahead(const char *p, uint64_t bytes) {
+        struct stat st;
+        char *ap = NULL, *line = NULL;
+        int r;
+        dev_t d;
+
+        assert(p);
+        assert(bytes);
+
+        if (stat(p, &st) < 0)
+                return -errno;
+
+        if (major(st.st_dev) == 0)
+                return 0;
+
+        d = st.st_dev;
+        block_get_whole_disk(d, &d);
+
+        if (asprintf(&ap, "/sys/dev/block/%u:%u/bdi/read_ahead_kb", major(d), minor(d)) < 0) {
+                r = -ENOMEM;
+                goto finish;
+        }
+
+        if (asprintf(&line, "%llu", bytes / 1024ULL) < 0) {
+                r = -ENOMEM;
+                goto finish;
+        }
+
+        r = write_string_file(ap, line);
+        if (r < 0)
+                goto finish;
+
+finish:
+        free(ap);
+        free(line);
+
+        return r;
+}
diff --git a/src/readahead/readahead-common.h b/src/readahead/readahead-common.h
new file mode 100644
index 0000000..b34f3aa
--- /dev/null
+++ b/src/readahead/readahead-common.h
@@ -0,0 +1,61 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include "macro.h"
+#include "util.h"
+
+#define READAHEAD_FILE_SIZE_MAX (10*1024*1024)
+
+#define READAHEAD_PACK_FILE_VERSION ";VERSION=2\n"
+
+extern unsigned arg_files_max;
+extern off_t arg_file_size_max;
+extern usec_t arg_timeout;
+
+int file_verify(int fd, const char *fn, off_t file_size_max, struct stat *st);
+
+int fs_on_ssd(const char *p);
+int fs_on_read_only(const char *p);
+
+bool enough_ram(void);
+
+int open_inotify(void);
+
+typedef struct ReadaheadShared {
+        pid_t collect;
+        pid_t replay;
+} _packed_ ReadaheadShared;
+
+ReadaheadShared *shared_get(void);
+
+int block_bump_request_nr(const char *p);
+
+int block_get_readahead(const char *p, uint64_t *bytes);
+int block_set_readahead(const char *p, uint64_t bytes);
+
+int main_collect(const char *root);
+int main_replay(const char *root);
+int main_analyze(const char *pack_path);
diff --git a/src/readahead/readahead-replay.c b/src/readahead/readahead-replay.c
new file mode 100644
index 0000000..f81e0fe
--- /dev/null
+++ b/src/readahead/readahead-replay.c
@@ -0,0 +1,281 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <inttypes.h>
+#include <fcntl.h>
+#include <linux/limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/select.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <getopt.h>
+#include <sys/inotify.h>
+
+#include "systemd/sd-daemon.h"
+
+#include "missing.h"
+#include "util.h"
+#include "set.h"
+#include "ioprio.h"
+#include "readahead-common.h"
+#include "virt.h"
+
+static ReadaheadShared *shared = NULL;
+
+static int unpack_file(FILE *pack) {
+        _cleanup_close_ int fd = -1;
+        char fn[PATH_MAX];
+        bool any = false;
+        struct stat st;
+        uint64_t inode;
+
+        assert(pack);
+
+        if (!fgets(fn, sizeof(fn), pack))
+                return 0;
+
+        char_array_0(fn);
+        truncate_nl(fn);
+
+        fd = open(fn, O_RDONLY|O_CLOEXEC|O_NOATIME|O_NOCTTY|O_NOFOLLOW);
+        if (fd < 0) {
+                if (errno != ENOENT && errno != EPERM && errno != EACCES && errno != ELOOP)
+                        log_warning("open(%s) failed: %m", fn);
+
+        } else if (file_verify(fd, fn, arg_file_size_max, &st) <= 0)
+                fd = safe_close(fd);
+
+        if (fread(&inode, sizeof(inode), 1, pack) != 1) {
+                log_error("Premature end of pack file.");
+                return -EIO;
+        }
+
+        if (fd >= 0) {
+                /* If the inode changed the file got deleted, so just
+                 * ignore this entry */
+                if (st.st_ino != (uint64_t) inode)
+                        fd = safe_close(fd);
+        }
+
+        for (;;) {
+                uint32_t b, c;
+
+                if (fread(&b, sizeof(b), 1, pack) != 1 ||
+                    fread(&c, sizeof(c), 1, pack) != 1) {
+                        log_error("Premature end of pack file.");
+                        return -EIO;
+                }
+
+                if (b == 0 && c == 0)
+                        break;
+
+                if (c <= b) {
+                        log_error("Invalid pack file.");
+                        return -EIO;
+                }
+
+                log_debug("%s: page %u to %u", fn, b, c);
+
+                any = true;
+
+                if (fd >= 0) {
+                        if (posix_fadvise(fd, b * page_size(), (c - b) * page_size(), POSIX_FADV_WILLNEED) < 0) {
+                                log_warning("posix_fadvise() failed: %m");
+                                return -errno;
+                        }
+                }
+        }
+
+        if (!any && fd >= 0) {
+                /* if no range is encoded in the pack file this is
+                 * intended to mean that the whole file shall be
+                 * read */
+
+                if (posix_fadvise(fd, 0, st.st_size, POSIX_FADV_WILLNEED) < 0) {
+                        log_warning("posix_fadvise() failed: %m");
+                        return -errno;
+                }
+        }
+
+        return 0;
+}
+
+static int replay(const char *root) {
+        _cleanup_close_ int inotify_fd = -1;
+        _cleanup_free_ char *pack_fn = NULL;
+        _cleanup_fclose_ FILE *pack = NULL;
+        bool on_ssd, ready = false;
+        char line[LINE_MAX];
+        int prio, c;
+
+        assert(root);
+
+        block_bump_request_nr(root);
+
+        if (asprintf(&pack_fn, "%s/.readahead", root) < 0)
+                return log_oom();
+
+        pack = fopen(pack_fn, "re");
+        if (!pack) {
+                if (errno == ENOENT) {
+                        log_debug("No pack file found.");
+                        return 0;
+                }
+
+                log_error("Failed to open pack file: %m");
+                return -errno;
+        }
+
+        posix_fadvise(fileno(pack), 0, 0, POSIX_FADV_WILLNEED);
+
+        inotify_fd = open_inotify();
+        if (inotify_fd < 0)
+                return inotify_fd;
+
+        if (!fgets(line, sizeof(line), pack)) {
+                log_error("Premature end of pack file.");
+                return -EIO;
+        }
+
+        char_array_0(line);
+
+        if (!streq(line, CANONICAL_HOST READAHEAD_PACK_FILE_VERSION)) {
+                log_debug("Pack file host or version type mismatch.");
+                goto done;
+        }
+
+        c = getc(pack);
+        if (c == EOF) {
+                log_debug("Premature end of pack file.");
+                return -EIO;
+        }
+
+        /* We do not retest SSD here, so that we can start replaying
+         * before udev is up.*/
+        on_ssd = c == 'S';
+        log_debug("On SSD: %s", yes_no(on_ssd));
+
+        if (on_ssd)
+                prio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0);
+        else
+                /* We are not using RT here, since we'd starve IO that
+                we didn't record (which is for example blkid, since
+                its disk accesses go directly to the block device and
+                are thus not visible in fallocate) to death. However,
+                we do ask for an IO prio that is slightly higher than
+                the default (which is BE. 4) */
+                prio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, 2);
+
+        if (ioprio_set(IOPRIO_WHO_PROCESS, getpid(), prio) < 0)
+                log_warning("Failed to set IDLE IO priority class: %m");
+
+        sd_notify(0, "STATUS=Replaying readahead data");
+
+        log_debug("Replaying...");
+
+        if (access("/run/systemd/readahead/noreplay", F_OK) >= 0) {
+                log_debug("Got termination request");
+                goto done;
+        }
+
+        while (!feof(pack) && !ferror(pack)) {
+                uint8_t inotify_buffer[sizeof(struct inotify_event) + FILENAME_MAX];
+                int k;
+                ssize_t n;
+
+                n = read(inotify_fd, &inotify_buffer, sizeof(inotify_buffer));
+                if (n < 0) {
+                        if (errno != EINTR && errno != EAGAIN) {
+                                log_error("Failed to read inotify event: %m");
+                                return -errno;
+                        }
+                } else {
+                        struct inotify_event *e = (struct inotify_event*) inotify_buffer;
+
+                        while (n > 0) {
+                                size_t step;
+
+                                if ((e->mask & IN_CREATE) && streq(e->name, "noreplay")) {
+                                        log_debug("Got termination request");
+                                        goto done;
+                                }
+
+                                step = sizeof(struct inotify_event) + e->len;
+                                assert(step <= (size_t) n);
+
+                                e = (struct inotify_event*) ((uint8_t*) e + step);
+                                n -= step;
+                        }
+                }
+
+                k = unpack_file(pack);
+                if (k < 0)
+                        return k;
+
+                if (!ready) {
+                        /* We delay the ready notification until we
+                         * queued at least one read */
+                        sd_notify(0, "READY=1");
+                        ready = true;
+                }
+        }
+
+done:
+        if (ferror(pack)) {
+                log_error("Failed to read pack file.");
+                return -EIO;
+        }
+
+        if (!ready)
+                sd_notify(0, "READY=1");
+
+        log_debug("Done.");
+        return 0;
+}
+
+int main_replay(const char *root) {
+
+        if (!root)
+                root = "/";
+
+        if (!enough_ram()) {
+                log_info("Disabling readahead replay due to low memory.");
+                return EXIT_SUCCESS;
+        }
+
+        shared = shared_get();
+        if (!shared)
+                return EXIT_FAILURE;
+
+        shared->replay = getpid();
+        __sync_synchronize();
+
+        if (replay(root) < 0)
+                return EXIT_FAILURE;
+
+        return EXIT_SUCCESS;
+}
diff --git a/src/readahead/readahead.c b/src/readahead/readahead.c
new file mode 100644
index 0000000..35176e9
--- /dev/null
+++ b/src/readahead/readahead.c
@@ -0,0 +1,163 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2012 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdio.h>
+#include <getopt.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+
+#include "util.h"
+#include "def.h"
+#include "build.h"
+#include "readahead-common.h"
+
+unsigned arg_files_max = 16*1024;
+off_t arg_file_size_max = READAHEAD_FILE_SIZE_MAX;
+usec_t arg_timeout = 2*USEC_PER_MINUTE;
+
+static void help(void) {
+        printf("%1$s [OPTIONS...] collect [DIRECTORY]\n\n"
+               "Collect read-ahead data on early boot.\n\n"
+               "  -h --help                 Show this help\n"
+               "     --version              Show package version\n"
+               "     --files-max=INT        Maximum number of files to read ahead\n"
+               "     --file-size-max=BYTES  Maximum size of files to read ahead\n"
+               "     --timeout=USEC         Maximum time to spend collecting data\n"
+               "\n\n"
+               "%1$s [OPTIONS...] replay [DIRECTORY]\n\n"
+               "Replay collected read-ahead data on early boot.\n\n"
+               "  -h --help                 Show this help\n"
+               "     --version              Show package version\n"
+               "     --file-size-max=BYTES  Maximum size of files to read ahead\n"
+               "\n\n"
+               "%1$s [OPTIONS...] analyze [PACK-FILE]\n\n"
+               "Analyze collected read-ahead data.\n\n"
+               "  -h --help                 Show this help\n"
+               "     --version              Show package version\n",
+               program_invocation_short_name);
+}
+
+static int parse_argv(int argc, char *argv[]) {
+
+        enum {
+                ARG_VERSION = 0x100,
+                ARG_FILES_MAX,
+                ARG_FILE_SIZE_MAX,
+                ARG_TIMEOUT
+        };
+
+        static const struct option options[] = {
+                { "help",          no_argument,       NULL, 'h'                },
+                { "version",       no_argument,       NULL, ARG_VERSION        },
+                { "files-max",     required_argument, NULL, ARG_FILES_MAX      },
+                { "file-size-max", required_argument, NULL, ARG_FILE_SIZE_MAX  },
+                { "timeout",       required_argument, NULL, ARG_TIMEOUT        },
+                {}
+        };
+
+        int c;
+
+        assert(argc >= 0);
+        assert(argv);
+
+        while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
+
+                switch (c) {
+
+                case 'h':
+                        help();
+                        return 0;
+
+                case ARG_VERSION:
+                        puts(PACKAGE_STRING);
+                        puts(SYSTEMD_FEATURES);
+                        return 0;
+
+                case ARG_FILES_MAX:
+                        if (safe_atou(optarg, &arg_files_max) < 0 || arg_files_max <= 0) {
+                                log_error("Failed to parse maximum number of files %s.", optarg);
+                                return -EINVAL;
+                        }
+                        break;
+
+                case ARG_FILE_SIZE_MAX: {
+                        unsigned long long ull;
+
+                        if (safe_atollu(optarg, &ull) < 0 || ull <= 0) {
+                                log_error("Failed to parse maximum file size %s.", optarg);
+                                return -EINVAL;
+                        }
+
+                        arg_file_size_max = (off_t) ull;
+                        break;
+                }
+
+                case ARG_TIMEOUT:
+                        if (parse_sec(optarg, &arg_timeout) < 0 || arg_timeout <= 0) {
+                                log_error("Failed to parse timeout %s.", optarg);
+                                return -EINVAL;
+                        }
+
+                        break;
+
+                case '?':
+                        return -EINVAL;
+
+                default:
+                        assert_not_reached("Unhandled option");
+                }
+
+        if (optind != argc-1 &&
+            optind != argc-2) {
+                log_error("%s: wrong number of arguments.",
+                          program_invocation_short_name);
+                return -EINVAL;
+        }
+
+        return 1;
+}
+
+int main(int argc, char *argv[]) {
+        int r;
+
+        log_set_target(LOG_TARGET_SAFE);
+        log_parse_environment();
+        log_open();
+
+        umask(0022);
+
+        r = parse_argv(argc, argv);
+        if (r <= 0)
+                return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+
+        if (streq(argv[optind], "collect"))
+                return main_collect(argv[optind+1]);
+        else if (streq(argv[optind], "replay"))
+                return main_replay(argv[optind+1]);
+        else if (streq(argv[optind], "analyze"))
+                return main_analyze(argv[optind+1]);
+
+        log_error("Unknown verb %s.", argv[optind]);
+        return EXIT_FAILURE;
+}
diff --git a/src/readahead/sd-readahead.c b/src/readahead/sd-readahead.c
new file mode 100644
index 0000000..675d82c
--- /dev/null
+++ b/src/readahead/sd-readahead.c
@@ -0,0 +1,89 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  Copyright 2010 Lennart Poettering
+
+  Permission is hereby granted, free of charge, to any person
+  obtaining a copy of this software and associated documentation files
+  (the "Software"), to deal in the Software without restriction,
+  including without limitation the rights to use, copy, modify, merge,
+  publish, distribute, sublicense, and/or sell copies of the Software,
+  and to permit persons to whom the Software is furnished to do so,
+  subject to the following conditions:
+
+  The above copyright notice and this permission notice shall be
+  included in all copies or substantial portions of the Software.
+
+  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+  BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+  SOFTWARE.
+***/
+
+#ifndef _GNU_SOURCE
+#  define _GNU_SOURCE
+#endif
+
+#include <unistd.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <string.h>
+
+#include "sd-readahead.h"
+
+#if (__GNUC__ >= 4)
+#  ifdef SD_EXPORT_SYMBOLS
+/* Export symbols */
+#    define _sd_export_ __attribute__ ((visibility("default")))
+#  else
+/* Don't export the symbols */
+#    define _sd_export_ __attribute__ ((visibility("hidden")))
+#  endif
+#else
+#  define _sd_export_
+#endif
+
+static int touch(const char *path) {
+
+#if !defined(DISABLE_SYSTEMD) && defined(__linux__)
+        int fd;
+
+        mkdir("/run/systemd", 0755);
+        mkdir("/run/systemd/readahead", 0755);
+
+        fd = open(path, O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY, 0666);
+        if (fd < 0)
+                return -errno;
+
+        for (;;) {
+                if (close(fd) >= 0)
+                        break;
+
+                if (errno != EINTR)
+                        return -errno;
+        }
+
+#endif
+        return 0;
+}
+
+_sd_export_ int sd_readahead(const char *action) {
+
+        if (!action)
+                return -EINVAL;
+
+        if (strcmp(action, "cancel") == 0)
+                return touch("/run/systemd/readahead/cancel");
+        else if (strcmp(action, "done") == 0)
+                return touch("/run/systemd/readahead/done");
+        else if (strcmp(action, "noreplay") == 0)
+                return touch("/run/systemd/readahead/noreplay");
+
+        return -EINVAL;
+}
diff --git a/src/readahead/test-ssd.c b/src/readahead/test-ssd.c
new file mode 100644
index 0000000..808faf3
--- /dev/null
+++ b/src/readahead/test-ssd.c
@@ -0,0 +1,41 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 Zbigniew Jędrzejewski-Szmek
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "readahead-common.h"
+
+int main(int argc, char *argv[]) {
+        int i;
+
+        for (i = 1; i < argc; i++) {
+                char *name = argv[i];
+                int r;
+
+                r = fs_on_ssd(name);
+                if (r < 0) {
+                        log_error("%s: %s", name, strerror(-r));
+                        return EXIT_FAILURE;
+                }
+
+                log_info("%s: %s", name, r ? "SSD" : "---");
+        }
+
+        return EXIT_SUCCESS;
+}
diff --git a/src/systemd/sd-readahead.h b/src/systemd/sd-readahead.h
new file mode 100644
index 0000000..bb30f9a
--- /dev/null
+++ b/src/systemd/sd-readahead.h
@@ -0,0 +1,73 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#ifndef foosdreadaheadhfoo
+#define foosdreadaheadhfoo
+
+/***
+  Copyright 2010 Lennart Poettering
+
+  Permission is hereby granted, free of charge, to any person
+  obtaining a copy of this software and associated documentation files
+  (the "Software"), to deal in the Software without restriction,
+  including without limitation the rights to use, copy, modify, merge,
+  publish, distribute, sublicense, and/or sell copies of the Software,
+  and to permit persons to whom the Software is furnished to do so,
+  subject to the following conditions:
+
+  The above copyright notice and this permission notice shall be
+  included in all copies or substantial portions of the Software.
+
+  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+  BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+  SOFTWARE.
+***/
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+  Reference implementation of a few boot read-ahead-related
+  interfaces. These interfaces are trivial to implement. To simplify
+  porting, we provide this reference implementation. Applications are
+  welcome to reimplement the algorithms described here if they do not
+  want to include these two source files.
+
+  You may compile this with -DDISABLE_SYSTEMD to disable systemd
+  support. This makes all calls NOPs.
+
+  Because this is drop-in code, we don't want any of our symbols to be
+  exported in any case. Hence, we declare hidden visibility for all of
+  them.
+
+  You may find an up-to-date version of these source files online:
+
+  http://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-readahead.h
+  http://cgit.freedesktop.org/systemd/systemd/plain/src/readahead/sd-readahead.c
+
+  This should compile on non-Linux systems too, but all functions
+  will become NOPs.
+
+  See sd-readahead(3) for more information.
+*/
+
+/*
+  Controls on-going disk read-ahead operations during boot-up. The argument
+  must be one of the following strings: "cancel", "done", or "noreplay".
+
+  cancel = terminate read-ahead data collection, and drop collected information
+  done = terminate read-ahead data collection, and keep collected information
+  noreplay = terminate read-ahead replay
+*/
+int sd_readahead(const char *action);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/system-preset/90-systemd.preset b/system-preset/90-systemd.preset
index ee1b864..24963f0 100644
--- a/system-preset/90-systemd.preset
+++ b/system-preset/90-systemd.preset
@@ -12,6 +12,7 @@ enable remote-fs.target
 enable machines.target
 
 enable getty@.service
+enable systemd-readahead-*
 enable systemd-timesyncd.service
 enable systemd-networkd.service
 enable systemd-resolved.service
diff --git a/units/.gitignore b/units/.gitignore
index 6fdb629..638a7ab 100644
--- a/units/.gitignore
+++ b/units/.gitignore
@@ -52,6 +52,9 @@
 /systemd-poweroff.service
 /systemd-quotacheck.service
 /systemd-random-seed.service
+/systemd-readahead-collect.service
+/systemd-readahead-done.service
+/systemd-readahead-replay.service
 /systemd-reboot.service
 /systemd-remount-fs.service
 /systemd-resolved.service
diff --git a/units/ldconfig.service b/units/ldconfig.service
index f9691e2..43c145b 100644
--- a/units/ldconfig.service
+++ b/units/ldconfig.service
@@ -10,7 +10,7 @@ Description=Rebuild Dynamic Linker Cache
 Documentation=man:ldconfig(8)
 DefaultDependencies=no
 Conflicts=shutdown.target
-After=systemd-remount-fs.service
+After=systemd-readahead-collect.service systemd-readahead-replay.service systemd-remount-fs.service
 Before=sysinit.target shutdown.target systemd-update-done.service
 ConditionNeedsUpdate=/etc
 
diff --git a/units/quotaon.service.in b/units/quotaon.service.in
index 7d59a40..49a50a7 100644
--- a/units/quotaon.service.in
+++ b/units/quotaon.service.in
@@ -9,7 +9,7 @@
 Description=Enable File System Quotas
 Documentation=man:quotaon(8)
 DefaultDependencies=no
-After=systemd-quotacheck.service
+After=systemd-readahead-collect.service systemd-readahead-replay.service systemd-quotacheck.service
 Before=local-fs.target shutdown.target
 ConditionPathExists=@QUOTAON@
 
diff --git a/units/system-update.target b/units/system-update.target
index 48d46fc..d0f847f 100644
--- a/units/system-update.target
+++ b/units/system-update.target
@@ -10,7 +10,7 @@ Description=System Update
 Documentation=http://freedesktop.org/wiki/Software/systemd/SystemUpdates
 Documentation=man:systemd.special(7) man:systemd-system-update-generator(8)
 Requires=sysinit.target
-Conflicts=shutdown.target
+Conflicts=shutdown.target systemd-readahead-collect.service systemd-readahead-replay.service
 After=sysinit.target
 Before=shutdown.target
 AllowIsolate=yes
diff --git a/units/systemd-backlight@.service.in b/units/systemd-backlight@.service.in
index 5e6706c..b146e30 100644
--- a/units/systemd-backlight@.service.in
+++ b/units/systemd-backlight@.service.in
@@ -11,7 +11,7 @@ Documentation=man:systemd-backlight@.service(8)
 DefaultDependencies=no
 RequiresMountsFor=/var/lib/systemd/backlight
 Conflicts=shutdown.target
-After=systemd-remount-fs.service
+After=systemd-readahead-collect.service systemd-readahead-replay.service systemd-remount-fs.service
 Before=sysinit.target shutdown.target
 
 [Service]
diff --git a/units/systemd-binfmt.service.in b/units/systemd-binfmt.service.in
index 34a5d52..02dfe77 100644
--- a/units/systemd-binfmt.service.in
+++ b/units/systemd-binfmt.service.in
@@ -11,7 +11,7 @@ Documentation=man:systemd-binfmt.service(8) man:binfmt.d(5)
 Documentation=https://www.kernel.org/doc/Documentation/binfmt_misc.txt
 DefaultDependencies=no
 Conflicts=shutdown.target
-After=proc-sys-fs-binfmt_misc.automount
+After=systemd-readahead-collect.service systemd-readahead-replay.service proc-sys-fs-binfmt_misc.automount
 Before=sysinit.target shutdown.target
 ConditionPathIsReadWrite=/proc/sys/
 ConditionDirectoryNotEmpty=|/lib/binfmt.d
diff --git a/units/systemd-firstboot.service.in b/units/systemd-firstboot.service.in
index 405c6f3..89fa7e1 100644
--- a/units/systemd-firstboot.service.in
+++ b/units/systemd-firstboot.service.in
@@ -10,7 +10,7 @@ Description=First Boot Wizard
 Documentation=man:systemd-firstboot(1)
 DefaultDependencies=no
 Conflicts=shutdown.target
-After=systemd-remount-fs.service
+After=systemd-readahead-collect.service systemd-readahead-replay.service systemd-remount-fs.service
 Before=systemd-sysusers.service sysinit.target shutdown.target
 ConditionPathIsReadWrite=/etc
 ConditionFirstBoot=yes
diff --git a/units/systemd-fsck-root.service.in b/units/systemd-fsck-root.service.in
index 6d76578..26cce51 100644
--- a/units/systemd-fsck-root.service.in
+++ b/units/systemd-fsck-root.service.in
@@ -9,6 +9,7 @@
 Description=File System Check on Root Device
 Documentation=man:systemd-fsck-root.service(8)
 DefaultDependencies=no
+After=systemd-readahead-collect.service systemd-readahead-replay.service
 Before=local-fs.target shutdown.target
 ConditionPathIsReadWrite=!/
 
diff --git a/units/systemd-fsck@.service.in b/units/systemd-fsck@.service.in
index 857e625..d2cda6a 100644
--- a/units/systemd-fsck@.service.in
+++ b/units/systemd-fsck@.service.in
@@ -10,7 +10,7 @@ Description=File System Check on %f
 Documentation=man:systemd-fsck@.service(8)
 DefaultDependencies=no
 BindsTo=%i.device
-After=%i.device systemd-fsck-root.service local-fs-pre.target
+After=systemd-readahead-collect.service systemd-readahead-replay.service %i.device systemd-fsck-root.service local-fs-pre.target
 Before=shutdown.target
 
 [Service]
diff --git a/units/systemd-hwdb-update.service.in b/units/systemd-hwdb-update.service.in
index 791528e..4bed482 100644
--- a/units/systemd-hwdb-update.service.in
+++ b/units/systemd-hwdb-update.service.in
@@ -10,7 +10,7 @@ Description=Rebuild Hardware Database
 Documentation=man:hwdb(7) man:systemd-hwdb(8)
 DefaultDependencies=no
 Conflicts=shutdown.target
-After=systemd-remount-fs.service
+After=systemd-readahead-collect.service systemd-readahead-replay.service systemd-remount-fs.service
 Before=sysinit.target shutdown.target systemd-update-done.service
 ConditionNeedsUpdate=/etc
 ConditionPathExists=|!@udevlibexecdir@/hwdb.bin
diff --git a/units/systemd-journal-catalog-update.service.in b/units/systemd-journal-catalog-update.service.in
index 6370dd4..5b85889 100644
--- a/units/systemd-journal-catalog-update.service.in
+++ b/units/systemd-journal-catalog-update.service.in
@@ -10,7 +10,7 @@ Description=Rebuild Journal Catalog
 Documentation=man:systemd-journald.service(8) man:journald.conf(5)
 DefaultDependencies=no
 Conflicts=shutdown.target
-After=local-fs.target
+After=systemd-readahead-collect.service systemd-readahead-replay.service local-fs.target
 Before=sysinit.target shutdown.target systemd-update-done.service
 ConditionNeedsUpdate=/etc
 
diff --git a/units/systemd-modules-load.service.in b/units/systemd-modules-load.service.in
index 040a0fe..32deb52 100644
--- a/units/systemd-modules-load.service.in
+++ b/units/systemd-modules-load.service.in
@@ -10,6 +10,7 @@ Description=Load Kernel Modules
 Documentation=man:systemd-modules-load.service(8) man:modules-load.d(5)
 DefaultDependencies=no
 Conflicts=shutdown.target
+After=systemd-readahead-collect.service systemd-readahead-replay.service
 Before=sysinit.target shutdown.target
 ConditionCapability=CAP_SYS_MODULE
 ConditionDirectoryNotEmpty=|/lib/modules-load.d
diff --git a/units/systemd-quotacheck.service.in b/units/systemd-quotacheck.service.in
index 5cb9bc3..f726ea1 100644
--- a/units/systemd-quotacheck.service.in
+++ b/units/systemd-quotacheck.service.in
@@ -9,7 +9,7 @@
 Description=File System Quota Check
 Documentation=man:systemd-quotacheck.service(8)
 DefaultDependencies=no
-After=systemd-remount-fs.service
+After=systemd-readahead-collect.service systemd-readahead-replay.service systemd-remount-fs.service
 Before=local-fs.target shutdown.target
 ConditionPathExists=@QUOTACHECK@
 
diff --git a/units/systemd-random-seed.service.in b/units/systemd-random-seed.service.in
index b55844b..1879b2f 100644
--- a/units/systemd-random-seed.service.in
+++ b/units/systemd-random-seed.service.in
@@ -11,7 +11,7 @@ Documentation=man:systemd-random-seed.service(8) man:random(4)
 DefaultDependencies=no
 RequiresMountsFor=@RANDOM_SEED@
 Conflicts=shutdown.target
-After=systemd-remount-fs.service
+After=systemd-readahead-collect.service systemd-readahead-replay.service systemd-remount-fs.service
 Before=sysinit.target shutdown.target
 
 [Service]
diff --git a/units/systemd-readahead-collect.service.in b/units/systemd-readahead-collect.service.in
new file mode 100644
index 0000000..d4b8e67
--- /dev/null
+++ b/units/systemd-readahead-collect.service.in
@@ -0,0 +1,28 @@
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+[Unit]
+Description=Collect Read-Ahead Data
+Documentation=man:systemd-readahead-replay.service(8)
+DefaultDependencies=no
+Wants=systemd-readahead-done.timer
+Conflicts=shutdown.target
+Before=sysinit.target shutdown.target
+ConditionPathExists=!/run/systemd/readahead/cancel
+ConditionPathExists=!/run/systemd/readahead/done
+ConditionVirtualization=no
+
+[Service]
+Type=notify
+ExecStart=@rootlibexecdir@/systemd-readahead collect
+RemainAfterExit=yes
+StandardOutput=null
+OOMScoreAdjust=1000
+
+[Install]
+WantedBy=default.target
+Also=systemd-readahead-drop.service
diff --git a/units/systemd-readahead-done.service.in b/units/systemd-readahead-done.service.in
new file mode 100644
index 0000000..e0d9579
--- /dev/null
+++ b/units/systemd-readahead-done.service.in
@@ -0,0 +1,22 @@
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+[Unit]
+Description=Stop Read-Ahead Data Collection
+Documentation=man:systemd-readahead-replay.service(8)
+DefaultDependencies=no
+Conflicts=shutdown.target
+After=default.target
+Before=shutdown.target
+ConditionVirtualization=no
+
+[Service]
+Type=oneshot
+ExecStart=@SYSTEMD_NOTIFY@ --readahead=done
+
+[Install]
+Also=systemd-readahead-collect.service
diff --git a/units/systemd-readahead-done.timer b/units/systemd-readahead-done.timer
new file mode 100644
index 0000000..c58e096
--- /dev/null
+++ b/units/systemd-readahead-done.timer
@@ -0,0 +1,22 @@
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+[Unit]
+Description=Stop Read-Ahead Data Collection 10s After Completed Startup
+Documentation=man:systemd-readahead-replay.service(8)
+DefaultDependencies=no
+Conflicts=shutdown.target
+After=default.target
+Before=shutdown.target
+ConditionVirtualization=no
+
+[Timer]
+OnActiveSec=30s
+AccuracySec=1s
+
+[Install]
+Also=systemd-readahead-collect.service
diff --git a/units/systemd-readahead-drop.service b/units/systemd-readahead-drop.service
new file mode 100644
index 0000000..d9d12bc
--- /dev/null
+++ b/units/systemd-readahead-drop.service
@@ -0,0 +1,19 @@
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+[Unit]
+Description=Drop Read-Ahead Data
+Documentation=man:systemd-readahead-replay.service(8)
+ConditionPathExists=/.readahead
+
+[Service]
+Type=oneshot
+ExecStart=/bin/rm -f /.readahead
+
+[Install]
+WantedBy=system-update.target
+Also=systemd-readahead-collect.service
diff --git a/units/systemd-readahead-replay.service.in b/units/systemd-readahead-replay.service.in
new file mode 100644
index 0000000..c64a533
--- /dev/null
+++ b/units/systemd-readahead-replay.service.in
@@ -0,0 +1,26 @@
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+[Unit]
+Description=Replay Read-Ahead Data
+Documentation=man:systemd-readahead-replay.service(8)
+DefaultDependencies=no
+Conflicts=shutdown.target
+Before=sysinit.target shutdown.target
+ConditionPathExists=!/run/systemd/readahead/noreplay
+ConditionPathExists=/.readahead
+ConditionVirtualization=no
+
+[Service]
+Type=notify
+ExecStart=@rootlibexecdir@/systemd-readahead replay
+RemainAfterExit=yes
+StandardOutput=null
+OOMScoreAdjust=1000
+
+[Install]
+WantedBy=default.target
diff --git a/units/systemd-remount-fs.service.in b/units/systemd-remount-fs.service.in
index 8d9daac..70e1a86 100644
--- a/units/systemd-remount-fs.service.in
+++ b/units/systemd-remount-fs.service.in
@@ -11,7 +11,7 @@ Documentation=man:systemd-remount-fs.service(8)
 Documentation=http://www.freedesktop.org/wiki/Software/systemd/APIFileSystems
 DefaultDependencies=no
 Conflicts=shutdown.target
-After=systemd-fsck-root.service
+After=systemd-readahead-collect.service systemd-readahead-replay.service systemd-fsck-root.service
 Before=local-fs-pre.target local-fs.target shutdown.target
 Wants=local-fs-pre.target
 ConditionPathExists=/etc/fstab
diff --git a/units/systemd-rfkill@.service.in b/units/systemd-rfkill@.service.in
index b48efe5..0d2757d 100644
--- a/units/systemd-rfkill@.service.in
+++ b/units/systemd-rfkill@.service.in
@@ -12,7 +12,7 @@ DefaultDependencies=no
 BindsTo=sys-subsystem-rfkill-devices-%i.device
 RequiresMountsFor=/var/lib/systemd/rfkill
 Conflicts=shutdown.target
-After=systemd-remount-fs.service
+After=systemd-readahead-collect.service systemd-readahead-replay.service systemd-remount-fs.service
 Before=sysinit.target shutdown.target
 
 [Service]
diff --git a/units/systemd-sysctl.service.in b/units/systemd-sysctl.service.in
index fa72085..ade9dc3 100644
--- a/units/systemd-sysctl.service.in
+++ b/units/systemd-sysctl.service.in
@@ -10,6 +10,7 @@ Description=Apply Kernel Variables
 Documentation=man:systemd-sysctl.service(8) man:sysctl.d(5)
 DefaultDependencies=no
 Conflicts=shutdown.target
+After=systemd-readahead-collect.service systemd-readahead-replay.service
 After=systemd-modules-load.service
 Before=sysinit.target shutdown.target
 ConditionPathIsReadWrite=/proc/sys/
diff --git a/units/systemd-sysusers.service.in b/units/systemd-sysusers.service.in
index ffd6d77..69fea11 100644
--- a/units/systemd-sysusers.service.in
+++ b/units/systemd-sysusers.service.in
@@ -10,7 +10,7 @@ Description=Create System Users
 Documentation=man:sysusers.d(5) man:systemd-sysusers.service(8)
 DefaultDependencies=no
 Conflicts=shutdown.target
-After=systemd-remount-fs.service
+After=systemd-readahead-collect.service systemd-readahead-replay.service systemd-remount-fs.service
 Before=sysinit.target shutdown.target systemd-update-done.service
 ConditionNeedsUpdate=/etc
 
diff --git a/units/systemd-tmpfiles-clean.service.in b/units/systemd-tmpfiles-clean.service.in
index 133c8c9..31b2378 100644
--- a/units/systemd-tmpfiles-clean.service.in
+++ b/units/systemd-tmpfiles-clean.service.in
@@ -10,7 +10,7 @@ Description=Cleanup of Temporary Directories
 Documentation=man:tmpfiles.d(5) man:systemd-tmpfiles(8)
 DefaultDependencies=no
 Conflicts=shutdown.target
-After=local-fs.target time-sync.target
+After=systemd-readahead-collect.service systemd-readahead-replay.service local-fs.target time-sync.target
 Before=shutdown.target
 
 [Service]
diff --git a/units/systemd-tmpfiles-setup-dev.service.in b/units/systemd-tmpfiles-setup-dev.service.in
index 0123a03..0b66c53 100644
--- a/units/systemd-tmpfiles-setup-dev.service.in
+++ b/units/systemd-tmpfiles-setup-dev.service.in
@@ -10,7 +10,7 @@ Description=Create Static Device Nodes in /dev
 Documentation=man:tmpfiles.d(5) man:systemd-tmpfiles(8)
 DefaultDependencies=no
 Conflicts=shutdown.target
-After=systemd-sysusers.service
+After=systemd-readahead-collect.service systemd-readahead-replay.service systemd-sysusers.service
 Before=sysinit.target local-fs-pre.target systemd-udevd.service shutdown.target
 ConditionCapability=CAP_SYS_MODULE
 
diff --git a/units/systemd-tmpfiles-setup.service.in b/units/systemd-tmpfiles-setup.service.in
index e895cda..72ab083 100644
--- a/units/systemd-tmpfiles-setup.service.in
+++ b/units/systemd-tmpfiles-setup.service.in
@@ -10,7 +10,7 @@ Description=Create Volatile Files and Directories
 Documentation=man:tmpfiles.d(5) man:systemd-tmpfiles(8)
 DefaultDependencies=no
 Conflicts=shutdown.target
-After=local-fs.target systemd-sysusers.service
+After=systemd-readahead-collect.service systemd-readahead-replay.service local-fs.target systemd-sysusers.service
 Before=sysinit.target shutdown.target
 RefuseManualStop=yes
 
diff --git a/units/systemd-update-done.service.in b/units/systemd-update-done.service.in
index ec7d906..7031bff 100644
--- a/units/systemd-update-done.service.in
+++ b/units/systemd-update-done.service.in
@@ -10,7 +10,7 @@ Description=Update is Completed
 Documentation=man:systemd-update-done.service(8)
 DefaultDependencies=no
 Conflicts=shutdown.target
-After=local-fs.target
+After=systemd-readahead-collect.service systemd-readahead-replay.service local-fs.target
 Before=sysinit.target shutdown.target
 ConditionNeedsUpdate=|/etc
 ConditionNeedsUpdate=|/var
diff --git a/units/systemd-update-utmp.service.in b/units/systemd-update-utmp.service.in
index 163eccd..da7dda7 100644
--- a/units/systemd-update-utmp.service.in
+++ b/units/systemd-update-utmp.service.in
@@ -11,7 +11,7 @@ Documentation=man:systemd-update-utmp.service(8) man:utmp(5)
 DefaultDependencies=no
 RequiresMountsFor=/var/log/wtmp
 Conflicts=shutdown.target
-After=systemd-remount-fs.service systemd-tmpfiles-setup.service auditd.service
+After=systemd-readahead-collect.service systemd-readahead-replay.service systemd-remount-fs.service systemd-tmpfiles-setup.service auditd.service
 Before=sysinit.target shutdown.target
 
 [Service]
diff --git a/units/systemd-vconsole-setup.service.in b/units/systemd-vconsole-setup.service.in
index 6160361..18faa63 100644
--- a/units/systemd-vconsole-setup.service.in
+++ b/units/systemd-vconsole-setup.service.in
@@ -10,6 +10,7 @@ Description=Setup Virtual Console
 Documentation=man:systemd-vconsole-setup.service(8) man:vconsole.conf(5)
 DefaultDependencies=no
 Conflicts=shutdown.target
+After=systemd-readahead-collect.service systemd-readahead-replay.service
 Before=sysinit.target shutdown.target
 ConditionPathExists=/dev/tty0