initd/zram.c

   1 #include <stdio.h>
   2 #include <unistd.h>
   3 #include <stdlib.h>
   4 #include <string.h>
   5 #include <errno.h>
   6 #include <fcntl.h>
   7
   8 #include <sys/utsname.h>
   9 #include <sys/mount.h>
  10 #include <sys/types.h>
  11 #include <sys/wait.h>
  12 #include <sys/stat.h>
  13
  14 #include "../log.h"
  15 #include "../container.h"
  16
  17 #include "init.h"
  18
  19 #define KB(x) (x * 1024)
  20
  21 #define ZRAM_MOD_PATH "/lib/modules/%s/zram.ko"
  22 #define EXT4_MOD_PATH "/lib/modules/%s/ext4.ko"
  23
  24 static long
  25 proc_meminfo(void)
  26 {
  27         FILE *fp;
  28         char line[256];
  29         char *key;
  30         long val = KB(16);
  31
  32         fp = fopen("/proc/meminfo", "r");
  33         if (fp == NULL) {
  34                 ERROR("Can't open /proc/meminfo: %m\n");
  35                 return errno;
  36         }
  37
  38         while (fgets(line, sizeof(line), fp)) {
  39                 key = strtok(line, ":");
  40                 if (strcasecmp(key, "MemTotal"))
  41                         continue;
  42                 val = atol(strtok(NULL, " kB\n"));
  43                 break;
  44         }
  45         fclose(fp);
  46
  47         if (val > KB(32))
  48                 val = KB(32);
  49
  50         return val;
  51 }
  52
  53 static int
  54 early_insmod(char *module)
  55 {
  56         pid_t pid = fork();
  57         char *modprobe[] = { "/sbin/modprobe", NULL, NULL };
  58
  59         if (!pid) {
  60                 char *path;
  61                 struct utsname ver;
  62
  63                 uname(&ver);
  64                 path = alloca(strlen(module) + strlen(ver.release) + 1);
  65                 sprintf(path, module, ver.release);
  66                 modprobe[1] = path;
  67                 execvp(modprobe[0], modprobe);
  68                 ERROR("Can't exec %s: %m\n", modprobe[0]);
  69                 exit(EXIT_FAILURE);
  70         }
  71
  72         if (pid <= 0) {
  73                 ERROR("Can't exec %s: %m\n", modprobe[0]);
  74                 return -1;
  75         } else {
  76                 waitpid(pid, NULL, 0);
  77         }
  78
  79         return 0;
  80 }
  81
  82
  83 int
  84 mount_zram_on_tmp(void)
  85 {
  86         char *mkfs[] = { "/usr/sbin/mkfs.ext4", "-b", "4096", "-F", "-L", "TEMP", "-m", "0", "/dev/zram0", NULL };
  87         FILE *fp;
  88         long zramsize;
  89         pid_t pid;
  90         int ret;
  91
  92         if (early_insmod(ZRAM_MOD_PATH) || early_insmod(EXT4_MOD_PATH)) {
  93                 ERROR("failed to insmod zram support\n");
  94                 return -1;
  95         }
  96
  97         mkdev("*", 0600);
  98
  99         zramsize = proc_meminfo() / 2;
 100         fp = fopen("/sys/block/zram0/disksize", "r+");
 101         if (fp == NULL) {
 102                 ERROR("Can't open /sys/block/zram0/disksize: %m\n");
 103                 return errno;
 104         }
 105         fprintf(fp, "%ld", KB(zramsize));
 106         fclose(fp);
 107
 108         pid = fork();
 109         if (!pid) {
 110                 execvp(mkfs[0], mkfs);
 111                 ERROR("Can't exec %s: %m\n", mkfs[0]);
 112                 exit(EXIT_FAILURE);
 113         } else if (pid <= 0) {
 114                 ERROR("Can't exec %s: %m\n", mkfs[0]);
 115                 return -1;
 116         } else {
 117                 waitpid(pid, NULL, 0);
 118         }
 119
 120         if (!is_container()) {
 121                 ret = mount("/dev/zram0", "/tmp", "ext4", MS_NOSUID | MS_NODEV | MS_NOATIME, "errors=continue,noquota");
 122                 if (ret < 0) {
 123                         ERROR("Can't mount /dev/zram0 on /tmp: %m\n");
 124                         return errno;
 125                 }
 126         }
 127
 128         LOG("Using up to %ld kB of RAM as ZRAM storage on /mnt\n", zramsize);
 129
 130         ret = chmod("/tmp", 01777);
 131         if (ret < 0) {
 132                 ERROR("Can't set /tmp mode to 1777: %m\n");
 133                 return errno;
 134         }
 135
 136         return 0;
 137 }