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hd-idle/hd-idle.c

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/*
* hd-idle.c - external disk idle daemon
*
* Copyright (c) 2007 Christian Mueller.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* hd-idle is a utility program for spinning-down external disks after a period
* of idle time. Since most external IDE disk enclosures don't support setting
* the IDE idle timer, a program like hd-idle is required to spin down idle
* disks automatically.
*
* A word of caution: hard disks don't like spinning-up too often. Laptop disks
* are more robust in this respect than desktop disks but if you set your disks
* to spin down after a few seconds you may damage the disk over time due to the
* stress the spin-up causes on the spindle motor and bearings. It seems that
* manufacturers recommend a minimum idle time of 3-5 minutes, the default in
* hd-idle is 10 minutes.
*
* Please note that hd-idle can spin down any disk accessible via the SCSI
* layer (USB, IEEE1394, ...) but it will NOT work with real SCSI disks because
* they don't spin up automatically. Thus it's not called scsi-idle and I don't
* recommend using it on a real SCSI system unless you have a kernel patch that
* automatically starts the SCSI disks after receiving a sense buffer indicating
* the disk has been stopped. Without such a patch, real SCSI disks won't start
* again and you can as well pull the plug.
*
* You have been warned...
*
* CVS Change Log:
* ---------------
*
* $Log: hd-idle.c,v $
* Revision 1.7 2014/04/06 19:53:51 cjmueller
* Version 1.05
* ------------
*
* Bugs:
* - Allow SCSI device names with more than one character (e.g. sdaa) in case
* there are more than 26 SCSI targets.
*
* Revision 1.6 2010/12/05 19:25:51 cjmueller
* Version 1.03
* ------------
*
* Bugs
* - Use %u in dprintf() when reporting number of reads and writes (the
* corresponding variable is an unsigned int).
* - Fix example in README where the parameter "-a" was written as "-n".
*
* Revision 1.5 2010/11/06 15:30:04 cjmueller
* Version 1.02
* ------------
*
* Features
* - In case the SCSI stop unit command fails with "check condition", print a
* hex dump of the sense buffer to stderr. This is supposed to help
* debugging.
*
* Revision 1.4 2010/02/26 14:03:44 cjmueller
* Version 1.01
* ------------
*
* Features
* - The parameter "-a" now also supports symlinks for disk names. Thus, disks
* can be specified using something like /dev/disk/by-uuid/... Use "-d" to
* verify that the resulting disk name is what you want.
*
* Please note that disk names are resolved to device nodes at startup. Also,
* since many entries in /dev/disk/by-xxx are actually partitions, partition
* numbers are automatically removed from the resulting device node.
*
* Bugs
* - Not really a bug, but the disk name comparison used strstr which is a bit
* useless because only disks starting with "sd" and a single letter after
* that are currently considered. Replaced the comparison with strcmp()
*
* Revision 1.3 2009/11/18 20:53:17 cjmueller
* Features
* - New parameter "-a" to allow selecting idle timeouts for individual disks;
* compatibility to previous releases is maintained by having an implicit
* default which matches all SCSI disks
*
* Bugs
* - Changed comparison operator for idle periods from '>' to '>=' to prevent
* adding one polling interval to idle time
* - Changed sleep time before calling sync after updating the log file to 1s
* (from 3s) to accumulate fewer dirty blocks before synching. It's still
* a compromize but the log file is for debugging purposes, anyway. A test
* with fsync() was unsuccessful because the next bdflush-initiated sync
* still caused spin-ups.
*
* Revision 1.2 2007/04/23 22:14:27 cjmueller
* Bug fixes
* - Comment changes; no functionality changes...
*
* Revision 1.1.1.1 2007/04/23 21:49:43 cjmueller
* initial import into CVS
*
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <ctype.h>
#include <errno.h>
#include <unistd.h>
#include <stdarg.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <scsi/sg.h>
#include <scsi/scsi.h>
#define STAT_FILE "/proc/diskstats"
#define DEFAULT_IDLE_TIME 600
#define dprintf if (debug) printf
/* typedefs and structures */
typedef struct IDLE_TIME {
struct IDLE_TIME *next;
char *name;
int idle_time;
} IDLE_TIME;
typedef struct DISKSTATS {
struct DISKSTATS *next;
char name[50];
int idle_time;
time_t last_io;
time_t spindown;
time_t spinup;
unsigned int spun_down : 1;
unsigned int reads;
unsigned int writes;
} DISKSTATS;
/* function prototypes */
static void daemonize (void);
static DISKSTATS *get_diskstats (const char *name);
static void spindown_disk (const char *name);
static void log_spinup (DISKSTATS *ds);
static char *disk_name (char *name);
static void phex (const void *p, int len,
const char *fmt, ...);
/* global/static variables */
IDLE_TIME *it_root;
DISKSTATS *ds_root;
char *logfile = "/dev/null";
int debug;
/* main function */
int main(int argc, char *argv[])
{
IDLE_TIME *it;
int have_logfile = 0;
int min_idle_time;
int sleep_time;
int opt;
/* create default idle-time parameter entry */
if ((it = malloc(sizeof(*it))) == NULL) {
fprintf(stderr, "out of memory\n");
exit(1);
}
it->next = NULL;
it->name = NULL;
it->idle_time = DEFAULT_IDLE_TIME;
it_root = it;
/* process command line options */
while ((opt = getopt(argc, argv, "t:a:i:l:dh")) != -1) {
switch (opt) {
case 't':
/* just spin-down the specified disk and exit */
spindown_disk(optarg);
return(0);
case 'a':
/* add a new set of idle-time parameters for this particular disk */
if ((it = malloc(sizeof(*it))) == NULL) {
fprintf(stderr, "out of memory\n");
return(2);
}
it->name = disk_name(optarg);
it->idle_time = DEFAULT_IDLE_TIME;
it->next = it_root;
it_root = it;
break;
case 'i':
/* set idle-time parameters for current (or default) disk */
it->idle_time = atoi(optarg);
break;
case 'l':
logfile = optarg;
have_logfile = 1;
break;
case 'd':
debug = 1;
break;
case 'h':
printf("usage: hd-idle [-t <disk>] [-a <name>] [-i <idle_time>] [-l <logfile>] [-d] [-h]\n");
return(0);
case ':':
fprintf(stderr, "error: option -%c requires an argument\n", optopt);
return(1);
case '?':
fprintf(stderr, "error: unknown option -%c\n", optopt);
return(1);
}
}
/* set sleep time to 1/10th of the shortest idle time */
min_idle_time = 1 << 30;
for (it = it_root; it != NULL; it = it->next) {
if (it->idle_time != 0 && it->idle_time < min_idle_time) {
min_idle_time = it->idle_time;
}
}
if ((sleep_time = min_idle_time / 10) == 0) {
sleep_time = 1;
}
/* daemonize unless we're running in debug mode */
if (!debug) {
daemonize();
}
/* main loop: probe for idle disks and stop them */
for (;;) {
DISKSTATS tmp;
FILE *fp;
char buf[200];
if ((fp = fopen(STAT_FILE, "r")) == NULL) {
perror(STAT_FILE);
return(2);
}
memset(&tmp, 0x00, sizeof(tmp));
while (fgets(buf, sizeof(buf), fp) != NULL) {
if (sscanf(buf, "%*d %*d %s %*u %*u %u %*u %*u %*u %u %*u %*u %*u %*u",
tmp.name, &tmp.reads, &tmp.writes) == 3) {
DISKSTATS *ds;
time_t now = time(NULL);
const char *s;
/* make sure this is a SCSI disk (sd[a-z]+) without partition number */
if (tmp.name[0] != 's' || tmp.name[1] != 'd') {
continue;
}
for (s = tmp.name + 2; isalpha(*s); s++);
if (*s != '\0') {
/* ignore disk partitions */
continue;
}
dprintf("probing %s: reads: %u, writes: %u\n", tmp.name, tmp.reads, tmp.writes);
/* get previous statistics for this disk */
ds = get_diskstats(tmp.name);
if (ds == NULL) {
/* new disk; just add it to the linked list */
if ((ds = malloc(sizeof(*ds))) == NULL) {
fprintf(stderr, "out of memory\n");
return(2);
}
memcpy(ds, &tmp, sizeof(*ds));
ds->last_io = now;
ds->spinup = ds->last_io;
ds->next = ds_root;
ds_root = ds;
/* find idle time for this disk (falling-back to default; default means
* 'it->name == NULL' and this entry will always be the last due to the
* way this single-linked list is built when parsing command line
* arguments)
*/
for (it = it_root; it != NULL; it = it->next) {
if (it->name == NULL || !strcmp(ds->name, it->name)) {
ds->idle_time = it->idle_time;
break;
}
}
} else if (ds->reads == tmp.reads && ds->writes == tmp.writes) {
if (!ds->spun_down) {
/* no activity on this disk and still running */
if (ds->idle_time != 0 && now - ds->last_io >= ds->idle_time) {
spindown_disk(ds->name);
ds->spindown = now;
ds->spun_down = 1;
}
}
} else {
/* disk had some activity */
if (ds->spun_down) {
/* disk was spun down, thus it has just spun up */
if (have_logfile) {
log_spinup(ds);
}
ds->spinup = now;
}
ds->reads = tmp.reads;
ds->writes = tmp.writes;
ds->last_io = now;
ds->spun_down = 0;
}
}
}
fclose(fp);
sleep(sleep_time);
}
return(0);
}
/* become a daemon */
static void daemonize(void)
{
int maxfd;
int i;
/* fork #1: exit parent process and continue in the background */
if ((i = fork()) < 0) {
perror("couldn't fork");
exit(2);
} else if (i > 0) {
_exit(0);
}
/* fork #2: detach from terminal and fork again so we can never regain
* access to the terminal */
setsid();
if ((i = fork()) < 0) {
perror("couldn't fork #2");
exit(2);
} else if (i > 0) {
_exit(0);
}
/* change to root directory and close file descriptors */
chdir("/");
maxfd = getdtablesize();
for (i = 0; i < maxfd; i++) {
close(i);
}
/* use /dev/null for stdin, stdout and stderr */
open("/dev/null", O_RDONLY);
open("/dev/null", O_WRONLY);
open("/dev/null", O_WRONLY);
}
/* get DISKSTATS entry by name of disk */
static DISKSTATS *get_diskstats(const char *name)
{
DISKSTATS *ds;
for (ds = ds_root; ds != NULL; ds = ds->next) {
if (!strcmp(ds->name, name)) {
return(ds);
}
}
return(NULL);
}
/* spin-down a disk */
static void spindown_disk(const char *name)
{
struct sg_io_hdr io_hdr;
unsigned char sense_buf[255];
char dev_name[100];
int fd;
dprintf("spindown: %s\n", name);
/* fabricate SCSI IO request */
memset(&io_hdr, 0x00, sizeof(io_hdr));
io_hdr.interface_id = 'S';
io_hdr.dxfer_direction = SG_DXFER_NONE;
/* SCSI stop unit command */
io_hdr.cmdp = (unsigned char *) "\x1b\x00\x00\x00\x00\x00";
io_hdr.cmd_len = 6;
io_hdr.sbp = sense_buf;
io_hdr.mx_sb_len = (unsigned char) sizeof(sense_buf);
/* open disk device (kernel 2.4 will probably need "sg" names here) */
snprintf(dev_name, sizeof(dev_name), "/dev/%s", name);
if ((fd = open(dev_name, O_RDONLY)) < 0) {
perror(dev_name);
return;
}
/* execute SCSI request */
if (ioctl(fd, SG_IO, &io_hdr) < 0) {
char buf[100];
snprintf(buf, sizeof(buf), "ioctl on %s:", name);
perror(buf);
} else if (io_hdr.masked_status != 0) {
fprintf(stderr, "error: SCSI command failed with status 0x%02x\n",
io_hdr.masked_status);
if (io_hdr.masked_status == CHECK_CONDITION) {
phex(sense_buf, io_hdr.sb_len_wr, "sense buffer:\n");
}
}
close(fd);
}
/* write a spin-up event message to the log file */
static void log_spinup(DISKSTATS *ds)
{
FILE *fp;
if ((fp = fopen(logfile, "a")) != NULL) {
/* Print statistics to logfile
*
* Note: This doesn't work too well if there are multiple disks
* because the I/O we're dealing with might be on another
* disk so we effectively wake up the disk the log file is
* stored on as well. Then again the logfile is a debugging
* option, so what...
*/
time_t now = time(NULL);
char tstr[20];
char dstr[20];
strftime(dstr, sizeof(dstr), "%Y-%m-%d", localtime(&now));
strftime(tstr, sizeof(tstr), "%H:%M:%S", localtime(&now));
fprintf(fp,
"date: %s, time: %s, disk: %s, running: %ld, stopped: %ld\n",
dstr, tstr, ds->name,
(long) ds->spindown - (long) ds->spinup,
(long) time(NULL) - (long) ds->spindown);
/* Sync to make sure writing to the logfile won't cause another
* spinup in 30 seconds (or whatever bdflush uses as flush interval).
*/
fclose(fp);
sleep(1);
sync();
}
}
/* Resolve disk names specified as "/dev/disk/by-xxx" or some other symlink.
* Please note that this function is only called during command line parsing
* and hd-idle per se does not support dynamic disk additions or removals at
* runtime.
*
* This might change in the future but would require some fiddling to avoid
* needless overhead -- after all, this was designed to run on tiny embedded
* devices, too.
*/
static char *disk_name(char *path)
{
ssize_t len;
char buf[256];
char *s;
if (*path != '/') {
/* just a disk name without /dev prefix */
return(path);
}
if ((len = readlink(path, buf, sizeof(buf) - 1)) <= 0) {
if (errno != EINVAL) {
/* couldn't resolve disk name */
return(path);
}
/* 'path' is not a symlink */
strncpy(buf, path, sizeof(buf) - 1);
buf[sizeof(buf)-1] = '\0';
len = strlen(buf);
}
buf[len] = '\0';
/* remove partition numbers, if any */
for (s = buf + strlen(buf) - 1; s >= buf && isdigit(*s); s--) {
*s = '\0';
}
/* Extract basename of the disk in /dev. Note that this assumes that the
* final target of the symlink (if any) resolves to /dev/sd*
*/
if ((s = strrchr(buf, '/')) != NULL) {
s++;
} else {
s = buf;
}
if ((s = strdup(s)) == NULL) {
fprintf(stderr, "out of memory");
exit(2);
}
if (debug) {
printf("using %s for %s\n", s, path);
}
return(s);
}
/* print hex dump to stderr (e.g. sense buffers) */
static void phex(const void *p, int len, const char *fmt, ...)
{
va_list va;
const unsigned char *buf = p;
int pos = 0;
int i;
/* print header */
va_start(va, fmt);
vfprintf(stderr, fmt, va);
/* print hex block */
while (len > 0) {
fprintf(stderr, "%08x ", pos);
/* print hex block */
for (i = 0; i < 16; i++) {
if (i < len) {
fprintf(stderr, "%c%02x", ((i == 8) ? '-' : ' '), buf[i]);
} else {
fprintf(stderr, " ");
}
}
/* print ASCII block */
fprintf(stderr, " ");
for (i = 0; i < ((len > 16) ? 16 : len); i++) {
fprintf(stderr, "%c", (buf[i] >= 32 && buf[i] < 128) ? buf[i] : '.');
}
fprintf(stderr, "\n");
pos += 16;
buf += 16;
len -= 16;
}
}
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