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Systemd/src/readahead-collect.c

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/*-*- 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 <inttypes.h>
#include <fcntl.h>
#include <linux/limits.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/select.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <linux/fanotify.h>
#include <sys/signalfd.h>
#include <sys/poll.h>
#include <sys/mman.h>
#include <linux/fs.h>
#include <linux/fiemap.h>
#include <sys/ioctl.h>
#include <sys/vfs.h>
#include <getopt.h>
#include <sys/inotify.h>
#include "missing.h"
#include "util.h"
#include "set.h"
#include "sd-daemon.h"
#include "ioprio.h"
#include "readahead-common.h"
/* fixme:
*
* - detect ssd on btrfs/lvm...
* - read ahead directories
* - sd_readahead_cancel
* - gzip?
* - remount rw?
* - handle files where nothing is in mincore
* - does ioprio_set work with fadvise()?
*/
static unsigned arg_files_max = 16*1024;
static off_t arg_file_size_max = READAHEAD_FILE_SIZE_MAX;
static usec_t arg_timeout = 2*USEC_PER_MINUTE;
static int btrfs_defrag(int fd) {
struct btrfs_ioctl_vol_args data;
zero(data);
data.fd = fd;
return ioctl(fd, BTRFS_IOC_DEFRAG, &data);
}
static int pack_file(FILE *pack, const char *fn, bool on_btrfs) {
struct stat st;
void *start = MAP_FAILED;
uint8_t *vec;
uint32_t b, c;
size_t l, pages;
bool mapped;
int r = 0, fd = -1, k;
assert(pack);
assert(fn);
if ((fd = open(fn, O_RDONLY|O_CLOEXEC|O_NOATIME|O_NOCTTY|O_NOFOLLOW)) < 0) {
log_warning("open(%s) failed: %m", fn);
r = -errno;
goto finish;
}
if ((k = file_verify(fd, fn, arg_file_size_max, &st)) <= 0) {
r = k;
goto finish;
}
if (on_btrfs)
btrfs_defrag(fd);
l = PAGE_ALIGN(st.st_size);
if ((start = mmap(NULL, l, PROT_READ, MAP_SHARED, fd, 0)) == MAP_FAILED) {
log_warning("mmap(%s) failed: %m", fn);
r = -errno;
goto finish;
}
pages = l / PAGE_SIZE;
vec = alloca(pages);
if (mincore(start, l, vec) < 0) {
log_warning("mincore(%s) failed: %m", fn);
r = -errno;
goto finish;
}
fputs(fn, pack);
fputc('\n', pack);
mapped = false;
for (c = 0; c < pages; c++) {
bool new_mapped = !!(vec[c] & 1);
if (!mapped && new_mapped)
b = c;
else if (mapped && !new_mapped) {
fwrite(&b, sizeof(b), 1, pack);
fwrite(&c, sizeof(c), 1, pack);
log_debug("%s: page %u to %u", fn, b, c);
}
mapped = new_mapped;
}
/* We don't write any range data if we should read the entire file */
if (mapped && b > 0) {
fwrite(&b, sizeof(b), 1, pack);
fwrite(&c, sizeof(c), 1, pack);
log_debug("%s: page %u to %u", fn, b, c);
}
/* End marker */
b = 0;
fwrite(&b, sizeof(b), 1, pack);
fwrite(&b, sizeof(b), 1, pack);
finish:
if (start != MAP_FAILED)
munmap(start, l);
if (fd >= 0)
close_nointr_nofail(fd);
return r;
}
static unsigned long fd_first_block(int fd) {
struct {
struct fiemap fiemap;
struct fiemap_extent extent;
} data;
zero(data);
data.fiemap.fm_length = ~0ULL;
data.fiemap.fm_extent_count = 1;
if (ioctl(fd, FS_IOC_FIEMAP, &data) < 0)
return 0;
if (data.fiemap.fm_mapped_extents <= 0)
return 0;
if (data.fiemap.fm_extents[0].fe_flags & FIEMAP_EXTENT_UNKNOWN)
return 0;
return (unsigned long) data.fiemap.fm_extents[0].fe_physical;
}
struct item {
const char *path;
unsigned long block;
};
static int qsort_compare(const void *a, const void *b) {
const struct item *i, *j;
i = a;
j = b;
if (i->block < j->block)
return -1;
if (i->block > j->block)
return 1;
return strcmp(i->path, j->path);
}
static int collect(const char *root) {
enum {
FD_FANOTIFY, /* Get the actualy fs events */
FD_SIGNAL,
FD_INOTIFY, /* We get notifications to quit early via this fd */
_FD_MAX
};
struct pollfd pollfd[_FD_MAX];
int fanotify_fd = -1, signal_fd = -1, inotify_fd = -1, r = 0;
pid_t my_pid;
Hashmap *files = NULL;
Iterator i;
char *p, *q;
sigset_t mask;
FILE *pack = NULL;
char *pack_fn_new = NULL, *pack_fn = NULL;
bool on_ssd, on_btrfs;
struct statfs sfs;
usec_t not_after;
assert(root);
write_one_line_file("/proc/self/oom_score_adj", "1000");
if (ioprio_set(IOPRIO_WHO_PROCESS, getpid(), IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0)) < 0)
log_warning("Failed to set IDLE IO priority class: %m");
assert_se(sigemptyset(&mask) == 0);
sigset_add_many(&mask, SIGINT, SIGTERM, -1);
assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
log_error("signalfd(): %m");
r = -errno;
goto finish;
}
if (!(files = hashmap_new(string_hash_func, string_compare_func))) {
log_error("Failed to allocate set.");
r = -ENOMEM;
goto finish;
}
if ((fanotify_fd = fanotify_init(FAN_CLOEXEC|FAN_NONBLOCK, O_RDONLY|O_LARGEFILE|O_CLOEXEC|O_NOATIME)) < 0) {
log_error("Failed to create fanotify object: %m");
r = -errno;
goto finish;
}
if (fanotify_mark(fanotify_fd, FAN_MARK_ADD|FAN_MARK_MOUNT, FAN_OPEN, AT_FDCWD, root) < 0) {
log_error("Failed to mark %s: %m", root);
r = -errno;
goto finish;
}
if ((inotify_fd = open_inotify()) < 0) {
r = inotify_fd;
goto finish;
}
not_after = now(CLOCK_MONOTONIC) + arg_timeout;
my_pid = getpid();
zero(pollfd);
pollfd[FD_FANOTIFY].fd = fanotify_fd;
pollfd[FD_FANOTIFY].events = POLLIN;
pollfd[FD_SIGNAL].fd = signal_fd;
pollfd[FD_SIGNAL].events = POLLIN;
pollfd[FD_INOTIFY].fd = inotify_fd;
pollfd[FD_INOTIFY].events = POLLIN;
sd_notify(0,
"READY=1\n"
"STATUS=Collecting readahead data");
log_debug("Collecting...");
if (access("/dev/.systemd/readahead/cancel", F_OK) >= 0) {
log_debug("Collection canceled");
r = -ECANCELED;
goto finish;
}
if (access("/dev/.systemd/readahead/done", F_OK) >= 0) {
log_debug("Got termination request");
goto done;
}
for (;;) {
union {
struct fanotify_event_metadata metadata;
char buffer[4096];
} data;
ssize_t n;
struct fanotify_event_metadata *m;
usec_t t;
int h;
if (hashmap_size(files) > arg_files_max) {
log_debug("Reached maximum number of read ahead files, ending collection.");
break;
}
t = now(CLOCK_MONOTONIC);
if (t >= not_after) {
log_debug("Reached maximum collection time, ending collection.");
break;
}
if ((h = poll(pollfd, _FD_MAX, (int) ((not_after - t) / USEC_PER_MSEC))) < 0) {
if (errno == EINTR)
continue;
log_error("poll(): %m");
r = -errno;
goto finish;
}
if (h == 0) {
log_debug("Reached maximum collection time, ending collection.");
break;
}
if (pollfd[FD_SIGNAL].revents) {
log_debug("Got signal.");
break;
}
if (pollfd[FD_INOTIFY].revents) {
uint8_t inotify_buffer[sizeof(struct inotify_event) + FILENAME_MAX];
struct inotify_event *e;
if ((n = read(inotify_fd, &inotify_buffer, sizeof(inotify_buffer))) < 0) {
if (errno == EINTR || errno == EAGAIN)
continue;
log_error("Failed to read inotify event: %m");
r = -errno;
goto finish;
}
e = (struct inotify_event*) inotify_buffer;
while (n > 0) {
size_t step;
if ((e->mask & IN_CREATE) && streq(e->name, "cancel")) {
log_debug("Collection canceled");
r = -ECANCELED;
goto finish;
}
if ((e->mask & IN_CREATE) && streq(e->name, "done")) {
log_debug("Got termination request");
goto done;
}
step = sizeof(struct inotify_event) + e->len;
assert(step <= (size_t) n);
e = (struct inotify_event*) ((uint8_t*) e + step);
n -= step;
}
}
if ((n = read(fanotify_fd, &data, sizeof(data))) < 0) {
if (errno == EINTR || errno == EAGAIN)
continue;
log_error("Failed to read event: %m");
r = -errno;
goto finish;
}
for (m = &data.metadata; FAN_EVENT_OK(m, n); m = FAN_EVENT_NEXT(m, n)) {
if (m->pid != my_pid && m->fd >= 0) {
char fn[PATH_MAX];
int k;
snprintf(fn, sizeof(fn), "/proc/self/fd/%i", m->fd);
char_array_0(fn);
if ((k = readlink_malloc(fn, &p)) >= 0) {
if (startswith(p, "/tmp") ||
hashmap_get(files, p))
/* Not interesting, or
* already read */
free(p);
else {
unsigned long ul;
ul = fd_first_block(m->fd);
if ((k = hashmap_put(files, p, ULONG_TO_PTR(ul))) < 0) {
log_warning("set_put() failed: %s", strerror(-k));
free(p);
}
}
} else
log_warning("readlink(%s) failed: %s", fn, strerror(-k));
}
if (m->fd)
close_nointr_nofail(m->fd);
}
}
done:
if (fanotify_fd >= 0) {
close_nointr_nofail(fanotify_fd);
fanotify_fd = -1;
}
log_debug("Writing Pack File...");
on_ssd = fs_on_ssd(root);
log_debug("On SSD: %s", yes_no(on_ssd));
on_btrfs = statfs(root, &sfs) >= 0 && sfs.f_type == BTRFS_SUPER_MAGIC;
log_debug("On btrfs: %s", yes_no(on_btrfs));
asprintf(&pack_fn, "%s/.readahead", root);
asprintf(&pack_fn_new, "%s/.readahead.new", root);
if (!pack_fn || !pack_fn_new) {
log_error("Out of memory");
r = -ENOMEM;
goto finish;
}
if (!(pack = fopen(pack_fn_new, "we"))) {
log_error("Failed to open pack file: %m");
r = -errno;
goto finish;
}
fputs(CANONICAL_HOST "\n", pack);
putc(on_ssd ? 'S' : 'R', pack);
if (on_ssd || on_btrfs) {
/* On SSD or on btrfs, just write things out in the
* order the files were accessed. */
HASHMAP_FOREACH_KEY(q, p, files, i)
pack_file(pack, p, on_btrfs);
} else {
struct item *ordered, *j;
unsigned k, n;
/* On rotating media, order things by the block
* numbers */
log_debug("Ordering...");
n = hashmap_size(files);
if (!(ordered = new(struct item, n))) {
log_error("Out of memory");
r = -ENOMEM;
goto finish;
}
j = ordered;
HASHMAP_FOREACH_KEY(q, p, files, i) {
j->path = p;
j->block = PTR_TO_ULONG(q);
j++;
}
assert(ordered + n == j);
qsort(ordered, n, sizeof(struct item), qsort_compare);
for (k = 0; k < n; k++)
pack_file(pack, ordered[k].path, on_btrfs);
free(ordered);
}
log_debug("Finalizing...");
fflush(pack);
if (ferror(pack)) {
log_error("Failed to write pack file.");
r = -EIO;
goto finish;
}
if (rename(pack_fn_new, pack_fn) < 0) {
log_error("Failed to rename readahead file: %m");
r = -errno;
goto finish;
}
fclose(pack);
pack = NULL;
log_debug("Done.");
finish:
if (fanotify_fd >= 0)
close_nointr_nofail(fanotify_fd);
if (signal_fd >= 0)
close_nointr_nofail(signal_fd);
if (inotify_fd >= 0)
close_nointr_nofail(inotify_fd);
if (pack) {
fclose(pack);
unlink(pack_fn_new);
}
free(pack_fn_new);
free(pack_fn);
while ((p = hashmap_steal_first_key(files)))
free(p);
hashmap_free(files);
return r;
}
static int help(void) {
printf("%s [OPTIONS...] [DIRECTORY]\n\n"
"Collect read-ahead data on early boot.\n\n"
" -h --help Show this help\n"
" --max-files=INT Maximum number of files to read ahead\n"
" --max-file-size=BYTES Maximum size of files to read ahead\n"
" --timeout=USEC Maximum time to spend collecting data\n",
program_invocation_short_name);
return 0;
}
static int parse_argv(int argc, char *argv[]) {
enum {
ARG_FILES_MAX = 0x100,
ARG_FILE_SIZE_MAX,
ARG_TIMEOUT
};
static const struct option options[] = {
{ "help", no_argument, NULL, 'h' },
{ "files-max", required_argument, NULL, ARG_FILES_MAX },
{ "file-size-max", required_argument, NULL, ARG_FILE_SIZE_MAX },
{ "timeout", required_argument, NULL, ARG_TIMEOUT },
{ NULL, 0, NULL, 0 }
};
int c;
assert(argc >= 0);
assert(argv);
while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0) {
switch (c) {
case 'h':
help();
return 0;
case ARG_FILES_MAX:
if (safe_atou(optarg, &arg_files_max) < 0 || arg_files_max <= 0) {
log_error("Failed to parse maximum number of files %s.", optarg);
return -EINVAL;
}
break;
case ARG_FILE_SIZE_MAX: {
unsigned long long ull;
if (safe_atollu(optarg, &ull) < 0 || ull <= 0) {
log_error("Failed to parse maximum file size %s.", optarg);
return -EINVAL;
}
arg_file_size_max = (off_t) ull;
break;
}
case ARG_TIMEOUT:
if (parse_usec(optarg, &arg_timeout) < 0 || arg_timeout <= 0) {
log_error("Failed to parse timeout %s.", optarg);
return -EINVAL;
}
break;
case '?':
return -EINVAL;
default:
log_error("Unknown option code %c", c);
return -EINVAL;
}
}
if (optind != argc &&
optind != argc-1) {
help();
return -EINVAL;
}
return 1;
}
int main(int argc, char *argv[]) {
int r;
log_set_target(LOG_TARGET_SYSLOG_OR_KMSG);
log_parse_environment();
log_open();
if ((r = parse_argv(argc, argv)) <= 0)
return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
if (!enough_ram()) {
log_info("Disabling readahead collector due to low memory.");
return 0;
}
if (collect(optind < argc ? argv[optind] : "/") < 0)
return 1;
return 0;
}
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