man/systemd-cgls.1 \
man/systemd-notify.1 \
man/sd_notify.3 \
+ man/sd_readahead.3 \
man/sd_booted.3 \
man/sd_listen_fds.3 \
man/sd_is_fifo.3 \
* readahead() vs. fadvise() vs. ioprio
+* unneeded
+
+* properly handle multiple inotify events per read() in path.c and util.c
+
External:
* place /etc/inittab with explaining blurb.
--- /dev/null
+<?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 General Public License as published by
+ the Free Software Foundation; either version 2 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
+ General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+-->
+
+<refentry id="sd_notify">
+
+ <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 read-ahead operations</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcsynopsisinfo>#include "sd-daemon.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 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 new-style daemons 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>/dev/.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/tree/src/sd-daemon.c"/>
+ resp. <ulink
+ url="http://cgit.freedesktop.org/systemd/tree/src/sd-daemon.h"/></para>
+
+ <para><function>sd_readahead()</function> is
+ implemented in the reference implementation's drop-in
+ <filename>sd-daemon.c</filename> and
+ <filename>sd-daemon.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_daemon</refentrytitle><manvolnum>7</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_daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>
semantics of this option see
<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>
</variablelist>
</refsect1>
static pid_t arg_pid = 0;
static const char *arg_status = NULL;
static bool arg_booted = false;
+static const char *arg_readahead = NULL;
static int help(void) {
printf("%s [OPTIONS...] [VARIABLE=VALUE...]\n\n"
"Notify the init system about service status updates.\n\n"
- " -h --help Show this help\n"
- " --ready Inform the init system about service start-up completion\n"
- " --pid[=PID] Set main pid of daemon\n"
- " --status=TEXT Set status text\n"
- " --booted Returns 0 if the system was booted up with systemd, non-zero otherwise\n",
+ " -h --help Show this help\n"
+ " --ready Inform the init system about service start-up completion\n"
+ " --pid[=PID] Set main pid of daemon\n"
+ " --status=TEXT Set status text\n"
+ " --booted Returns 0 if the system was booted up with systemd, non-zero otherwise\n"
+ " --readahead=ACTION Controls read-ahead operations\n",
program_invocation_short_name);
return 0;
ARG_READY = 0x100,
ARG_PID,
ARG_STATUS,
- ARG_BOOTED
+ ARG_BOOTED,
+ ARG_READAHEAD
};
static const struct option options[] = {
- { "help", no_argument, NULL, 'h' },
- { "ready", no_argument, NULL, ARG_READY },
- { "pid", optional_argument, NULL, ARG_PID },
- { "status", required_argument, NULL, ARG_STATUS },
- { "booted", no_argument, NULL, ARG_BOOTED },
- { NULL, 0, NULL, 0 }
+ { "help", no_argument, NULL, 'h' },
+ { "ready", no_argument, NULL, ARG_READY },
+ { "pid", optional_argument, NULL, ARG_PID },
+ { "status", required_argument, NULL, ARG_STATUS },
+ { "booted", no_argument, NULL, ARG_BOOTED },
+ { "readahead", required_argument, NULL, ARG_READAHEAD },
+ { NULL, 0, NULL, 0 }
};
int c;
arg_booted = true;
break;
+ case ARG_READAHEAD:
+ arg_readahead = optarg;
+ break;
+
case '?':
return -EINVAL;
!arg_ready &&
!arg_status &&
!arg_pid &&
- !arg_booted) {
+ !arg_booted &&
+ !arg_readahead) {
help();
return -EINVAL;
}
if (arg_booted)
return sd_booted() <= 0;
+ if (arg_readahead) {
+ if ((r = sd_readahead(arg_readahead)) < 0) {
+ log_error("Failed to issue read-ahead control command: %s", strerror(-r));
+ goto finish;
+ }
+ }
+
if (arg_ready)
our_env[i++] = (char*) "READY=1";
#include <sys/ioctl.h>
#include <sys/vfs.h>
#include <getopt.h>
+#include <sys/inotify.h>
#include "missing.h"
#include "util.h"
* - sd_readahead_cancel
* - gzip?
* - remount rw?
+ * - handle files where nothing is in mincore
* - does ioprio_set work with fadvise()?
*/
static int collect(const char *root) {
enum {
- FD_FANOTIFY,
+ FD_FANOTIFY, /* Get the actualy 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, r = 0;
+ int fanotify_fd = -1, signal_fd = -1, inotify_fd = -1, r = 0;
pid_t my_pid;
Hashmap *files = NULL;
Iterator i;
goto finish;
}
+ if ((inotify_fd = open_inotify()) < 0) {
+ r = inotify_fd;
+ goto finish;
+ }
+
not_after = now(CLOCK_MONOTONIC) + arg_timeout;
my_pid = getpid();
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"
log_debug("Collecting...");
+ if (access("/dev/.systemd/readahead/cancel", F_OK) >= 0) {
+ log_debug("Collection canceled");
+ r = -ECANCELED;
+ goto finish;
+ }
+
+ if (access("/dev/.systemd/readahead/done", F_OK) >= 0) {
+ log_debug("Got termination request");
+ goto done;
+ }
+
for (;;) {
union {
struct fanotify_event_metadata metadata;
goto finish;
}
- if (pollfd[FD_SIGNAL].revents != 0)
- break;
-
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;
+ }
+ }
+
if ((n = read(fanotify_fd, &data, sizeof(data))) < 0) {
if (errno == EINTR || errno == EAGAIN)
}
}
+done:
if (fanotify_fd >= 0) {
close_nointr_nofail(fanotify_fd);
fanotify_fd = -1;
if (signal_fd >= 0)
close_nointr_nofail(signal_fd);
+ if (inotify_fd >= 0)
+ close_nointr_nofail(inotify_fd);
+
if (pack) {
fclose(pack);
unlink(pack_fn_new);
#include <stdlib.h>
#include <string.h>
#include <sys/sysinfo.h>
+#include <sys/inotify.h>
#include "log.h"
#include "readahead-common.h"
* with at least 128MB
* memory */
}
+
+int open_inotify(void) {
+ int fd;
+
+ if ((fd = inotify_init1(IN_CLOEXEC|IN_NONBLOCK)) < 0) {
+ log_error("Failed to create inotify handle: %m");
+ return -errno;
+ }
+
+ mkdir("/dev/.systemd", 0755);
+ mkdir("/dev/.systemd/readahead", 0755);
+
+ if (inotify_add_watch(fd, "/dev/.systemd/readahead", IN_CREATE) < 0) {
+ log_error("Failed to watch /dev/.systemd/readahead: %m");
+ close_nointr_nofail(fd);
+ return -errno;
+ }
+
+ return fd;
+}
bool enough_ram(void);
+int open_inotify(void);
+
#endif
#include <sys/stat.h>
#include <unistd.h>
#include <getopt.h>
+#include <sys/inotify.h>
#include "missing.h"
#include "util.h"
char *pack_fn = NULL, c;
bool on_ssd, ready = false;
int prio;
+ int inotify_fd = -1;
assert(root);
goto finish;
}
+ if ((inotify_fd = open_inotify()) < 0) {
+ r = inotify_fd;
+ goto finish;
+ }
+
if (!(fgets(line, sizeof(line), pack))) {
log_error("Premature end of pack file.");
r = -EIO;
log_debug("Replaying...");
+ if (access("/dev/.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;
+
+ if ((n = read(inotify_fd, &inotify_buffer, sizeof(inotify_buffer))) < 0) {
+ if (errno != EINTR && errno != EAGAIN) {
+ log_error("Failed to read inotify event: %m");
+ r = -errno;
+ goto finish;
+ }
+ } 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;
+ }
+ }
if ((k = unpack_file(pack)) < 0) {
r = k;
}
}
+done:
if (!ready)
sd_notify(0, "READY=1");
if (pack)
fclose(pack);
+ if (inotify_fd >= 0)
+ close_nointr_nofail(inotify_fd);
+
free(pack_fn);
return r;
return a.st_dev != b.st_dev;
#endif
}
+
+static int touch(const char *path) {
+
+#if !defined(DISABLE_SYSTEMD) && defined(__linux__)
+ int fd;
+
+ mkdir("/dev/.systemd", 0755);
+ mkdir("/dev/.systemd/readahead", 0755);
+
+ if ((fd = open(path, O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY, 0666)) < 0)
+ return -errno;
+
+ for (;;) {
+ if (close(fd) >= 0)
+ break;
+
+ if (errno != -EINTR)
+ return -errno;
+ }
+
+#endif
+ return 0;
+}
+
+int sd_readahead(const char *action) {
+
+ if (!action)
+ return -EINVAL;
+
+ if (strcmp(action, "cancel") == 0)
+ return touch("/dev/.systemd/readahead/cancel");
+ else if (strcmp(action, "done") == 0)
+ return touch("/dev/.systemd/readahead/done");
+ else if (strcmp(action, "noreplay") == 0)
+ return touch("/dev/.systemd/readahead/noreplay");
+
+ return -EINVAL;
+}
*/
int sd_booted(void) _sd_hidden_;
+/*
+ Controls ongoing disk read-ahead operations during boot-up. The argument
+ must be a string, and either "cancel", "done" or "noreplay".
+
+ cancel = terminate read-ahead data collection, drop collected information
+ done = terminate read-ahead data collection, keep collected information
+ noreplay = terminate read-ahead replay
+*/
+int sd_readahead(const char *action);
+
#ifdef __cplusplus
}
#endif
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