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-rw-r--r--src/readahead/readahead-collect.c623
1 files changed, 623 insertions, 0 deletions
diff --git a/src/readahead/readahead-collect.c b/src/readahead/readahead-collect.c
new file mode 100644
index 0000000000..5d07f4704a
--- /dev/null
+++ b/src/readahead/readahead-collect.c
@@ -0,0 +1,623 @@
+/*-*- 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 Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser 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>
+
+#ifdef HAVE_FANOTIFY_INIT
+#include <sys/fanotify.h>
+#endif
+
+#include <systemd/sd-daemon.h>
+
+#include "missing.h"
+#include "util.h"
+#include "set.h"
+#include "ioprio.h"
+#include "readahead-common.h"
+#include "virt.h"
+
+/* fixme:
+ *
+ * - detect ssd on btrfs/lvm...
+ * - read ahead directories
+ * - gzip?
+ * - remount rw?
+ * - handle files where nothing is in mincore
+ * - does ioprio_set work with fadvise()?
+ */
+
+static ReadaheadShared *shared = NULL;
+
+/* Avoid collisions with the NULL pointer */
+#define SECTOR_TO_PTR(s) ULONG_TO_PTR((s)+1)
+#define PTR_TO_SECTOR(p) (PTR_TO_ULONG(p)-1)
+
+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;
+ uint64_t inode;
+ size_t l, pages;
+ bool mapped;
+ int r = 0, fd = -1, k;
+
+ assert(pack);
+ assert(fn);
+
+ fd = open(fn, O_RDONLY|O_CLOEXEC|O_NOATIME|O_NOCTTY|O_NOFOLLOW);
+ if (fd < 0) {
+
+ if (errno == ENOENT)
+ return 0;
+
+ if (errno == EPERM || errno == EACCES)
+ return 0;
+
+ log_warning("open(%s) failed: %m", fn);
+ r = -errno;
+ goto finish;
+ }
+
+ k = file_verify(fd, fn, arg_file_size_max, &st);
+ if (k <= 0) {
+ r = k;
+ goto finish;
+ }
+
+ if (on_btrfs)
+ btrfs_defrag(fd);
+
+ l = PAGE_ALIGN(st.st_size);
+ start = mmap(NULL, l, PROT_READ, MAP_SHARED, fd, 0);
+ if (start == MAP_FAILED) {
+ log_warning("mmap(%s) failed: %m", fn);
+ r = -errno;
+ goto finish;
+ }
+
+ pages = l / page_size();
+ vec = alloca(pages);
+ memset(vec, 0, pages);
+ if (mincore(start, l, vec) < 0) {
+ log_warning("mincore(%s) failed: %m", fn);
+ r = -errno;
+ goto finish;
+ }
+
+ fputs(fn, pack);
+ fputc('\n', pack);
+
+ /* Store the inode, so that we notice when the file is deleted */
+ inode = (uint64_t) st.st_ino;
+ fwrite(&inode, sizeof(inode), 1, 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 actual 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;
+ uint64_t previous_block_readahead;
+ bool previous_block_readahead_set = false;
+
+ assert(root);
+
+ if (asprintf(&pack_fn, "%s/.readahead", root) < 0) {
+ r = log_oom();
+ goto finish;
+ }
+
+ /* If there's no pack file yet we lower the kernel readahead
+ * so that mincore() is accurate. If there is a pack file
+ * already we assume it is accurate enough so that kernel
+ * readahead is never triggered. */
+ previous_block_readahead_set =
+ access(pack_fn, F_OK) < 0 &&
+ block_get_readahead(root, &previous_block_readahead) >= 0 &&
+ block_set_readahead(root, 8*1024) >= 0;
+
+ 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("/run/systemd/readahead/cancel", F_OK) >= 0) {
+ log_debug("Collection canceled");
+ r = -ECANCELED;
+ goto finish;
+ }
+
+ if (access("/run/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;
+
+ /* fanotify sometimes returns EACCES on read()
+ * where it shouldn't. For now let's just
+ * ignore it here (which is safe), but
+ * eventually this should be
+ * dropped when the kernel is fixed.
+ *
+ * https://bugzilla.redhat.com/show_bug.cgi?id=707577 */
+ if (errno == EACCES)
+ 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)) {
+ char fn[PATH_MAX];
+ int k;
+
+ if (m->fd < 0)
+ goto next_iteration;
+
+ if (m->pid == my_pid)
+ goto next_iteration;
+
+ __sync_synchronize();
+ if (m->pid == shared->replay)
+ goto next_iteration;
+
+ 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") ||
+ endswith(p, " (deleted)") ||
+ 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, SECTOR_TO_PTR(ul))) < 0) {
+ log_warning("set_put() failed: %s", strerror(-k));
+ free(p);
+ }
+ }
+
+ } else
+ log_warning("readlink(%s) failed: %s", fn, strerror(-k));
+
+ next_iteration:
+ if (m->fd >= 0)
+ 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) > 0;
+ log_debug("On SSD: %s", yes_no(on_ssd));
+
+ on_btrfs = statfs(root, &sfs) >= 0 && (long) sfs.f_type == (long) BTRFS_SUPER_MAGIC;
+ log_debug("On btrfs: %s", yes_no(on_btrfs));
+
+ if (asprintf(&pack_fn_new, "%s/.readahead.new", root) < 0) {
+ r = log_oom();
+ goto finish;
+ }
+
+ pack = fopen(pack_fn_new, "we");
+ if (!pack) {
+ log_error("Failed to open pack file: %m");
+ r = -errno;
+ goto finish;
+ }
+
+ fputs(CANONICAL_HOST READAHEAD_PACK_FILE_VERSION, 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))) {
+ r = log_oom();
+ goto finish;
+ }
+
+ j = ordered;
+ HASHMAP_FOREACH_KEY(q, p, files, i) {
+ j->path = p;
+ j->block = PTR_TO_SECTOR(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);
+
+ if (previous_block_readahead_set) {
+ uint64_t bytes;
+
+ /* Restore the original kernel readahead setting if we
+ * changed it, and nobody has overwritten it since
+ * yet. */
+ if (block_get_readahead(root, &bytes) >= 0 && bytes == 8*1024)
+ block_set_readahead(root, previous_block_readahead);
+ }
+
+ return r;
+}
+
+int main_collect(const char *root) {
+
+ if (!root)
+ root = "/";
+
+ /* Skip this step on read-only media. Note that we check the
+ * underlying block device here, not he read-only flag of the
+ * file system on top, since that one is most likely mounted
+ * read-only anyway at boot, even if the underlying block
+ * device is theoretically writable. */
+ if (fs_on_read_only(root) > 0) {
+ log_info("Disabling readahead collector due to read-only media.");
+ return EXIT_SUCCESS;
+ }
+
+ if (!enough_ram()) {
+ log_info("Disabling readahead collector due to low memory.");
+ return EXIT_SUCCESS;
+ }
+
+ shared = shared_get();
+ if (!shared)
+ return EXIT_FAILURE;
+
+ shared->collect = getpid();
+ __sync_synchronize();
+
+ if (collect(root) < 0)
+ return EXIT_FAILURE;
+
+ return EXIT_SUCCESS;
+}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-23 15:08:53 +0000