+
+bool enough_ram(void) {
+ struct sysinfo si;
+
+ assert_se(sysinfo(&si) >= 0);
+
+ return si.totalram > 127 * 1024*1024; /* Enable readahead only
+ * 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;
+}
+
+ReadaheadShared *shared_get(void) {
+ int fd;
+ ReadaheadShared *m = NULL;
+
+ mkdir("/dev/.systemd", 0755);
+ mkdir("/dev/.systemd/readahead", 0755);
+
+ if ((fd = open("/dev/.systemd/readahead/shared", O_CREAT|O_RDWR|O_CLOEXEC, 0644)) < 0) {
+ log_error("Failed to create shared memory segment: %m");
+ goto finish;
+ }
+
+ if (ftruncate(fd, sizeof(ReadaheadShared)) < 0) {
+ log_error("Failed to truncate shared memory segment: %m");
+ goto finish;
+ }
+
+ if ((m = mmap(NULL, sizeof(ReadaheadShared), PROT_WRITE|PROT_READ, MAP_SHARED, fd, 0)) == MAP_FAILED) {
+ log_error("Failed to mmap shared memory segment: %m");
+ m = NULL;
+ goto finish;
+ }
+
+finish:
+ if (fd >= 0)
+ close_nointr_nofail(fd);
+
+ return m;
+}