src/readahead-common.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <errno.h>
  23 #include <libudev.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <sys/sysinfo.h>
  27 #include <sys/inotify.h>
  28 #include <fcntl.h>
  29 #include <sys/mman.h>
  30 #include <unistd.h>
  31
  32 #include "log.h"
  33 #include "readahead-common.h"
  34 #include "util.h"
  35
  36 int file_verify(int fd, const char *fn, off_t file_size_max, struct stat *st) {
  37         assert(fd >= 0);
  38         assert(fn);
  39         assert(st);
  40
  41         if (fstat(fd, st) < 0) {
  42                 log_warning("fstat(%s) failed: %m", fn);
  43                 return -errno;
  44         }
  45
  46         if (!S_ISREG(st->st_mode)) {
  47                 log_debug("Not preloading special file %s", fn);
  48                 return 0;
  49         }
  50
  51         if (st->st_size <= 0 || st->st_size > file_size_max) {
  52                 log_debug("Not preloading file %s with size out of bounds %zi", fn, st->st_size);
  53                 return 0;
  54         }
  55
  56         return 1;
  57 }
  58
  59 int fs_on_ssd(const char *p) {
  60         struct stat st;
  61         struct udev *udev = NULL;
  62         struct udev_device *udev_device = NULL, *look_at = NULL;
  63         bool b = false;
  64         const char *devtype, *rotational, *model, *id;
  65
  66         assert(p);
  67
  68         if (stat(p, &st) < 0)
  69                 return -errno;
  70
  71         if (!(udev = udev_new()))
  72                 return -ENOMEM;
  73
  74         if (!(udev_device = udev_device_new_from_devnum(udev, 'b', st.st_dev)))
  75                 goto finish;
  76
  77         if ((devtype = udev_device_get_property_value(udev_device, "DEVTYPE")) &&
  78             streq(devtype, "partition"))
  79                 look_at = udev_device_get_parent(udev_device);
  80         else
  81                 look_at = udev_device;
  82
  83         if (!look_at)
  84                 goto finish;
  85
  86         /* First, try high-level property */
  87         if ((id = udev_device_get_property_value(look_at, "ID_SSD"))) {
  88                 b = streq(id, "1");
  89                 goto finish;
  90         }
  91
  92         /* Second, try kernel attribute */
  93         if ((rotational = udev_device_get_sysattr_value(look_at, "queue/rotational")))
  94                 if ((b = streq(rotational, "0")))
  95                         goto finish;
  96
  97         /* Finally, fallback to heuristics */
  98         if (!(look_at = udev_device_get_parent(look_at)))
  99                 goto finish;
 100
 101         if ((model = udev_device_get_sysattr_value(look_at, "model")))
 102                 b = !!strstr(model, "SSD");
 103
 104 finish:
 105         if (udev_device)
 106                 udev_device_unref(udev_device);
 107
 108         if (udev)
 109                 udev_unref(udev);
 110
 111         return b;
 112 }
 113
 114 bool enough_ram(void) {
 115         struct sysinfo si;
 116
 117         assert_se(sysinfo(&si) >= 0);
 118
 119         return si.totalram > 127 * 1024*1024; /* Enable readahead only
 120                                                * with at least 128MB
 121                                                * memory */
 122 }
 123
 124 int open_inotify(void) {
 125         int fd;
 126
 127         if ((fd = inotify_init1(IN_CLOEXEC|IN_NONBLOCK)) < 0) {
 128                 log_error("Failed to create inotify handle: %m");
 129                 return -errno;
 130         }
 131
 132         mkdir("/dev/.systemd", 0755);
 133         mkdir("/dev/.systemd/readahead", 0755);
 134
 135         if (inotify_add_watch(fd, "/dev/.systemd/readahead", IN_CREATE) < 0) {
 136                 log_error("Failed to watch /dev/.systemd/readahead: %m");
 137                 close_nointr_nofail(fd);
 138                 return -errno;
 139         }
 140
 141         return fd;
 142 }
 143
 144 ReadaheadShared *shared_get(void) {
 145         int fd;
 146         ReadaheadShared *m = NULL;
 147
 148         mkdir("/dev/.systemd", 0755);
 149         mkdir("/dev/.systemd/readahead", 0755);
 150
 151         if ((fd = open("/dev/.systemd/readahead/shared", O_CREAT|O_RDWR|O_CLOEXEC, 0644)) < 0) {
 152                 log_error("Failed to create shared memory segment: %m");
 153                 goto finish;
 154         }
 155
 156         if (ftruncate(fd, sizeof(ReadaheadShared)) < 0) {
 157                 log_error("Failed to truncate shared memory segment: %m");
 158                 goto finish;
 159         }
 160
 161         if ((m = mmap(NULL, sizeof(ReadaheadShared), PROT_WRITE|PROT_READ, MAP_SHARED, fd, 0)) == MAP_FAILED) {
 162                 log_error("Failed to mmap shared memory segment: %m");
 163                 m = NULL;
 164                 goto finish;
 165         }
 166
 167 finish:
 168         if (fd >= 0)
 169                 close_nointr_nofail(fd);
 170
 171         return m;
 172 }