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 int fs_on_read_only(const char *p) {
 118         struct stat st;
 119         struct udev *udev = NULL;
 120         struct udev_device *udev_device = NULL;
 121         bool b = false;
 122         const char *read_only;
 123
 124         assert(p);
 125
 126         if (stat(p, &st) < 0)
 127                 return -errno;
 128
 129         if (major(st.st_dev) == 0)
 130                 return false;
 131
 132         if (!(udev = udev_new()))
 133                 return -ENOMEM;
 134
 135         if (!(udev_device = udev_device_new_from_devnum(udev, 'b', st.st_dev)))
 136                 goto finish;
 137
 138         if ((read_only = udev_device_get_sysattr_value(udev_device, "ro")))
 139                 if ((b = streq(read_only, "1")))
 140                         goto finish;
 141
 142 finish:
 143         if (udev_device)
 144                 udev_device_unref(udev_device);
 145
 146         if (udev)
 147                 udev_unref(udev);
 148
 149         return b;
 150 }
 151
 152 bool enough_ram(void) {
 153         struct sysinfo si;
 154
 155         assert_se(sysinfo(&si) >= 0);
 156
 157         /* Enable readahead only with at least 128MB memory */
 158         return si.totalram > 127 * 1024*1024 / si.mem_unit;
 159 }
 160
 161 int open_inotify(void) {
 162         int fd;
 163
 164         if ((fd = inotify_init1(IN_CLOEXEC|IN_NONBLOCK)) < 0) {
 165                 log_error("Failed to create inotify handle: %m");
 166                 return -errno;
 167         }
 168
 169         mkdir("/run/systemd", 0755);
 170         mkdir("/run/systemd/readahead", 0755);
 171
 172         if (inotify_add_watch(fd, "/run/systemd/readahead", IN_CREATE) < 0) {
 173                 log_error("Failed to watch /run/systemd/readahead: %m");
 174                 close_nointr_nofail(fd);
 175                 return -errno;
 176         }
 177
 178         return fd;
 179 }
 180
 181 ReadaheadShared *shared_get(void) {
 182         int fd;
 183         ReadaheadShared *m = NULL;
 184
 185         mkdir("/run/systemd", 0755);
 186         mkdir("/run/systemd/readahead", 0755);
 187
 188         if ((fd = open("/run/systemd/readahead/shared", O_CREAT|O_RDWR|O_CLOEXEC, 0644)) < 0) {
 189                 log_error("Failed to create shared memory segment: %m");
 190                 goto finish;
 191         }
 192
 193         if (ftruncate(fd, sizeof(ReadaheadShared)) < 0) {
 194                 log_error("Failed to truncate shared memory segment: %m");
 195                 goto finish;
 196         }
 197
 198         if ((m = mmap(NULL, sizeof(ReadaheadShared), PROT_WRITE|PROT_READ, MAP_SHARED, fd, 0)) == MAP_FAILED) {
 199                 log_error("Failed to mmap shared memory segment: %m");
 200                 m = NULL;
 201                 goto finish;
 202         }
 203
 204 finish:
 205         if (fd >= 0)
 206                 close_nointr_nofail(fd);
 207
 208         return m;
 209 }
 210
 211 #define BUMP_REQUEST_NR (16*1024)
 212
 213 int bump_request_nr(const char *p) {
 214         struct stat st;
 215         struct udev *udev = NULL;
 216         struct udev_device *udev_device = NULL, *look_at = NULL;
 217         const char *nr_requests;
 218         uint64_t u;
 219         char nr[64], *ap = NULL;
 220         int r;
 221
 222         assert(p);
 223
 224         if (stat(p, &st) < 0)
 225                 return -errno;
 226
 227         if (major(st.st_dev) == 0)
 228                 return 0;
 229
 230         if (!(udev = udev_new()))
 231                 return -ENOMEM;
 232
 233         if (!(udev_device = udev_device_new_from_devnum(udev, 'b', st.st_dev))) {
 234                 r = -ENOENT;
 235                 goto finish;
 236         }
 237
 238         look_at = udev_device;
 239         if (!(nr_requests = udev_device_get_sysattr_value(look_at, "queue/nr_requests"))) {
 240
 241                 /* Hmm, if the block device doesn't have a queue
 242                  * subdir, the let's look in the parent */
 243                 look_at = udev_device_get_parent(udev_device);
 244                 nr_requests = udev_device_get_sysattr_value(look_at, "queue/nr_requests");
 245         }
 246
 247         if (!nr_requests) {
 248                 r = -ENOENT;
 249                 goto finish;
 250         }
 251
 252         if (safe_atou64(nr_requests, &u) >= 0 && u >= BUMP_REQUEST_NR) {
 253                 r = 0;
 254                 goto finish;
 255         }
 256
 257         if (asprintf(&ap, "%s/queue/nr_requests", udev_device_get_syspath(look_at)) < 0) {
 258                 r = -ENOMEM;
 259                 goto finish;
 260         }
 261
 262         snprintf(nr, sizeof(nr), "%lu", (unsigned long) BUMP_REQUEST_NR);
 263
 264         if ((r = write_one_line_file(ap, nr)) < 0)
 265                 goto finish;
 266
 267         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);
 268         r = 1;
 269
 270 finish:
 271         if (udev_device)
 272                 udev_device_unref(udev_device);
 273
 274         if (udev)
 275                 udev_unref(udev);
 276
 277         free(ap);
 278
 279         return r;
 280 }