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 <stdlib.h>
  24 #include <string.h>
  25 #include <sys/sysinfo.h>
  26 #include <sys/inotify.h>
  27 #include <fcntl.h>
  28 #include <sys/mman.h>
  29 #include <unistd.h>
  30 #include <libudev.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 %llu", fn, (unsigned long long) 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 (major(st.st_dev) == 0)
  72                 return false;
  73
  74         if (!(udev = udev_new()))
  75                 return -ENOMEM;
  76
  77         if (!(udev_device = udev_device_new_from_devnum(udev, 'b', st.st_dev)))
  78                 goto finish;
  79
  80         if ((devtype = udev_device_get_property_value(udev_device, "DEVTYPE")) &&
  81             streq(devtype, "partition"))
  82                 look_at = udev_device_get_parent(udev_device);
  83         else
  84                 look_at = udev_device;
  85
  86         if (!look_at)
  87                 goto finish;
  88
  89         /* First, try high-level property */
  90         if ((id = udev_device_get_property_value(look_at, "ID_SSD"))) {
  91                 b = streq(id, "1");
  92                 goto finish;
  93         }
  94
  95         /* Second, try kernel attribute */
  96         if ((rotational = udev_device_get_sysattr_value(look_at, "queue/rotational")))
  97                 if ((b = streq(rotational, "0")))
  98                         goto finish;
  99
 100         /* Finally, fallback to heuristics */
 101         if (!(look_at = udev_device_get_parent(look_at)))
 102                 goto finish;
 103
 104         if ((model = udev_device_get_sysattr_value(look_at, "model")))
 105                 b = !!strstr(model, "SSD");
 106
 107 finish:
 108         if (udev_device)
 109                 udev_device_unref(udev_device);
 110
 111         if (udev)
 112                 udev_unref(udev);
 113
 114         return b;
 115 }
 116
 117 bool enough_ram(void) {
 118         struct sysinfo si;
 119
 120         assert_se(sysinfo(&si) >= 0);
 121
 122         return si.totalram > 127 * 1024*1024; /* Enable readahead only
 123                                                * with at least 128MB
 124                                                * memory */
 125 }
 126
 127 int open_inotify(void) {
 128         int fd;
 129
 130         if ((fd = inotify_init1(IN_CLOEXEC|IN_NONBLOCK)) < 0) {
 131                 log_error("Failed to create inotify handle: %m");
 132                 return -errno;
 133         }
 134
 135         mkdir("/dev/.systemd", 0755);
 136         mkdir("/dev/.systemd/readahead", 0755);
 137
 138         if (inotify_add_watch(fd, "/dev/.systemd/readahead", IN_CREATE) < 0) {
 139                 log_error("Failed to watch /dev/.systemd/readahead: %m");
 140                 close_nointr_nofail(fd);
 141                 return -errno;
 142         }
 143
 144         return fd;
 145 }
 146
 147 ReadaheadShared *shared_get(void) {
 148         int fd;
 149         ReadaheadShared *m = NULL;
 150
 151         mkdir("/dev/.systemd", 0755);
 152         mkdir("/dev/.systemd/readahead", 0755);
 153
 154         if ((fd = open("/dev/.systemd/readahead/shared", O_CREAT|O_RDWR|O_CLOEXEC, 0644)) < 0) {
 155                 log_error("Failed to create shared memory segment: %m");
 156                 goto finish;
 157         }
 158
 159         if (ftruncate(fd, sizeof(ReadaheadShared)) < 0) {
 160                 log_error("Failed to truncate shared memory segment: %m");
 161                 goto finish;
 162         }
 163
 164         if ((m = mmap(NULL, sizeof(ReadaheadShared), PROT_WRITE|PROT_READ, MAP_SHARED, fd, 0)) == MAP_FAILED) {
 165                 log_error("Failed to mmap shared memory segment: %m");
 166                 m = NULL;
 167                 goto finish;
 168         }
 169
 170 finish:
 171         if (fd >= 0)
 172                 close_nointr_nofail(fd);
 173
 174         return m;
 175 }
 176
 177
 178 #define BUMP_REQUEST_NR (16*1024)
 179
 180 int bump_request_nr(const char *p) {
 181         struct stat st;
 182         struct udev *udev = NULL;
 183         struct udev_device *udev_device = NULL, *look_at = NULL;
 184         const char *nr_requests;
 185         uint64_t u;
 186         char nr[64], *ap = NULL;
 187         int r;
 188
 189         assert(p);
 190
 191         if (stat(p, &st) < 0)
 192                 return -errno;
 193
 194         if (major(st.st_dev) == 0)
 195                 return 0;
 196
 197         if (!(udev = udev_new()))
 198                 return -ENOMEM;
 199
 200         if (!(udev_device = udev_device_new_from_devnum(udev, 'b', st.st_dev))) {
 201                 r = -ENOENT;
 202                 goto finish;
 203         }
 204
 205         look_at = udev_device;
 206         if (!(nr_requests = udev_device_get_sysattr_value(look_at, "queue/nr_requests"))) {
 207
 208                 /* Hmm, if the block device doesn't have a queue
 209                  * subdir, the let's look in the parent */
 210                 look_at = udev_device_get_parent(udev_device);
 211                 nr_requests = udev_device_get_sysattr_value(look_at, "queue/nr_requests");
 212         }
 213
 214         if (!nr_requests) {
 215                 r = -ENOENT;
 216                 goto finish;
 217         }
 218
 219         if (safe_atou64(nr_requests, &u) >= 0 && u >= BUMP_REQUEST_NR) {
 220                 r = 0;
 221                 goto finish;
 222         }
 223
 224         if (asprintf(&ap, "%s/queue/nr_requests", udev_device_get_syspath(look_at)) < 0) {
 225                 r = -ENOMEM;
 226                 goto finish;
 227         }
 228
 229         snprintf(nr, sizeof(nr), "%lu", (unsigned long) BUMP_REQUEST_NR);
 230
 231         if ((r = write_one_line_file(ap, nr)) < 0)
 232                 goto finish;
 233
 234         log_info("Bumped block_nr parameter of %s to %lu. This is a temporary hack and should be removed one day.", udev_device_get_devnode(look_at), (unsigned long) BUMP_REQUEST_NR);
 235         r = 1;
 236
 237 finish:
 238         if (udev_device)
 239                 udev_device_unref(udev_device);
 240
 241         if (udev)
 242                 udev_unref(udev);
 243
 244         free(ap);
 245
 246         return r;
 247 }