readahead-common.c revision 2b590e135f53a1bd3e771bdc555f7bf28c4cd232
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd 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.
systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/sysinfo.h>
#include <sys/inotify.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>
#include <libudev.h>
#include "log.h"
#include "readahead-common.h"
#include "util.h"
int file_verify(int fd, const char *fn, off_t file_size_max, struct stat *st) {
assert(fd >= 0);
assert(fn);
assert(st);
if (fstat(fd, st) < 0) {
log_warning("fstat(%s) failed: %m", fn);
return -errno;
}
if (!S_ISREG(st->st_mode)) {
log_debug("Not preloading special file %s", fn);
return 0;
}
if (st->st_size <= 0 || st->st_size > file_size_max) {
log_debug("Not preloading file %s with size out of bounds %llu", fn, (unsigned long long) st->st_size);
return 0;
}
return 1;
}
int fs_on_ssd(const char *p) {
struct stat st;
struct udev *udev = NULL;
struct udev_device *udev_device = NULL, *look_at = NULL;
bool b = false;
const char *devtype, *rotational, *model, *id;
assert(p);
if (stat(p, &st) < 0)
return -errno;
if (major(st.st_dev) == 0)
return false;
if (!(udev = udev_new()))
return -ENOMEM;
if (!(udev_device = udev_device_new_from_devnum(udev, 'b', st.st_dev)))
goto finish;
if ((devtype = udev_device_get_property_value(udev_device, "DEVTYPE")) &&
streq(devtype, "partition"))
look_at = udev_device_get_parent(udev_device);
else
look_at = udev_device;
if (!look_at)
goto finish;
/* First, try high-level property */
if ((id = udev_device_get_property_value(look_at, "ID_SSD"))) {
b = streq(id, "1");
goto finish;
}
/* Second, try kernel attribute */
if ((rotational = udev_device_get_sysattr_value(look_at, "queue/rotational")))
if ((b = streq(rotational, "0")))
goto finish;
/* Finally, fallback to heuristics */
if (!(look_at = udev_device_get_parent(look_at)))
goto finish;
if ((model = udev_device_get_sysattr_value(look_at, "model")))
b = !!strstr(model, "SSD");
finish:
if (udev_device)
udev_device_unref(udev_device);
if (udev)
udev_unref(udev);
return b;
}
int fs_on_read_only(const char *p) {
struct stat st;
struct udev *udev = NULL;
struct udev_device *udev_device = NULL;
bool b = false;
const char *read_only;
assert(p);
if (stat(p, &st) < 0)
return -errno;
if (major(st.st_dev) == 0)
return false;
if (!(udev = udev_new()))
return -ENOMEM;
if (!(udev_device = udev_device_new_from_devnum(udev, 'b', st.st_dev)))
goto finish;
if ((read_only = udev_device_get_sysattr_value(udev_device, "ro")))
if ((b = streq(read_only, "1")))
goto finish;
finish:
if (udev_device)
udev_device_unref(udev_device);
if (udev)
udev_unref(udev);
return b;
}
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;
}
#define BUMP_REQUEST_NR (16*1024)
int bump_request_nr(const char *p) {
struct stat st;
struct udev *udev = NULL;
struct udev_device *udev_device = NULL, *look_at = NULL;
const char *nr_requests;
uint64_t u;
char nr[64], *ap = NULL;
int r;
assert(p);
if (stat(p, &st) < 0)
return -errno;
if (major(st.st_dev) == 0)
return 0;
if (!(udev = udev_new()))
return -ENOMEM;
if (!(udev_device = udev_device_new_from_devnum(udev, 'b', st.st_dev))) {
r = -ENOENT;
goto finish;
}
look_at = udev_device;
if (!(nr_requests = udev_device_get_sysattr_value(look_at, "queue/nr_requests"))) {
/* Hmm, if the block device doesn't have a queue
* subdir, the let's look in the parent */
look_at = udev_device_get_parent(udev_device);
nr_requests = udev_device_get_sysattr_value(look_at, "queue/nr_requests");
}
if (!nr_requests) {
r = -ENOENT;
goto finish;
}
if (safe_atou64(nr_requests, &u) >= 0 && u >= BUMP_REQUEST_NR) {
r = 0;
goto finish;
}
if (asprintf(&ap, "%s/queue/nr_requests", udev_device_get_syspath(look_at)) < 0) {
r = -ENOMEM;
goto finish;
}
snprintf(nr, sizeof(nr), "%lu", (unsigned long) BUMP_REQUEST_NR);
if ((r = write_one_line_file(ap, nr)) < 0)
goto finish;
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);
r = 1;
finish:
if (udev_device)
udev_device_unref(udev_device);
if (udev)
udev_unref(udev);
free(ap);
return r;
}