/*-*- 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> #include <math.h> #ifdef HAVE_LINUX_BTRFS_H #include <linux/btrfs.h> #endif #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; static usec_t starttime; /* 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 = { .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 = alloca0(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 = { .fiemap.fm_length = ~0ULL, .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; unsigned long bin; }; static int qsort_compare(const void *a, const void *b) { const struct item *i, *j; i = a; j = b; /* sort by bin first */ if (i->bin < j->bin) return -1; if (i->bin > j->bin) return 1; /* then sort by sector */ 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; } starttime = now(CLOCK_MONOTONIC); /* 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; } files = hashmap_new(string_hash_func, string_compare_func); if (!files) { log_error("Failed to allocate set."); r = -ENOMEM; goto finish; } fanotify_fd = fanotify_init(FAN_CLOEXEC|FAN_NONBLOCK, O_RDONLY|O_LARGEFILE|O_CLOEXEC|O_NOATIME); if (fanotify_fd < 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; } inotify_fd = open_inotify(); if (inotify_fd < 0) { r = inotify_fd; goto finish; } not_after = now(CLOCK_MONOTONIC) + arg_timeout; my_pid = getpid(); 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; } } n = read(fanotify_fd, &data, sizeof(data)); if (n < 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[sizeof("/proc/self/fd/") + DECIMAL_STR_MAX(int)]; 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); k = readlink_malloc(fn, &p); if (k >= 0) { if (startswith(p, "/tmp") || endswith(p, " (deleted)") || hashmap_get(files, p)) /* Not interesting, or * already read */ free(p); else { unsigned long ul; usec_t entrytime; struct item *entry; entry = new0(struct item, 1); if (!entry) { r = log_oom(); goto finish; } ul = fd_first_block(m->fd); entrytime = now(CLOCK_MONOTONIC); entry->block = ul; entry->path = strdup(p); if (!entry->path) { free(entry); r = log_oom(); goto finish; } entry->bin = (entrytime - starttime) / 2000000; k = hashmap_put(files, p, entry); if (k < 0) { log_warning("hashmap_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 && F_TYPE_EQUAL(sfs.f_type, 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 { unsigned n; /* On rotating media, order things by the block * numbers */ log_debug("Ordering..."); n = hashmap_size(files); if (n) { _cleanup_free_ struct item *ordered; struct item *j; unsigned k; ordered = new(struct item, n); if (!ordered) { r = log_oom(); goto finish; } j = ordered; HASHMAP_FOREACH_KEY(q, p, files, i) { memcpy(j, q, sizeof(struct item)); 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); } else log_warning("No pack files"); } 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; }