| Message ID | 155905634517.1662.7843563955043166854.stgit@warthog.procyon.org.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | VFS: Introduce filesystem information query syscall [ver #13] | expand |
On 28/05/2019 16:12, David Howells wrote: > Implement a program to demonstrate mount listing using the new fsinfo() > syscall, Great. I understand this is only for demonstration, but IMO the output would be clearer with a few tweaks: > for example: > > # ./test-mntinfo Can we have a header please? E.g. MNT ID NOTIFS TYPE DEVICE -------------------------------------- -------- -------- ---- ------ > ROOT 5d c ext4 8:12 > \_ sys 13 8 sysfs 0:13 > | \_ kernel/security 16 0 securityfs 0:7 I assume ID is the same ID which is shown in /proc/mounts. But it's shown as decimal there. Can we match that? And can we show NOTIFS in decimal as well? I find counters easier to read in decimal :-). I.e. change "%8x" to "%10d" in both cases. major:minor is also more often seen formatted as "%d:%d": in /proc/self/mountinfo, lsblk, and ls -l. I don't feel as strongly about this one though. Thanks Alan > | \_ fs/cgroup 1a 10 tmpfs 0:17 > | | \_ unified 1b 0 cgroup2 0:18 > | | \_ systemd 1c 0 cgroup 0:19 > | | \_ freezer 20 0 cgroup 0:1d > | | \_ cpu,cpuacct 21 0 cgroup 0:1e > | | \_ memory 22 0 cgroup 0:1f > | | \_ cpuset 23 0 cgroup 0:20 > | | \_ hugetlb 24 0 cgroup 0:21 > | | \_ net_cls,net_prio 25 0 cgroup 0:22 > | | \_ blkio 26 0 cgroup 0:23 > | | \_ perf_event 27 0 cgroup 0:24 > | | \_ devices 28 0 cgroup 0:25 > | | \_ rdma 29 0 cgroup 0:26 > | \_ fs/pstore 1d 0 pstore 0:1a > | \_ firmware/efi/efivars 1e 0 efivarfs 0:1b > | \_ fs/bpf 1f 0 bpf 0:1c > | \_ kernel/config 5a 0 configfs 0:10 > | \_ fs/selinux 2a 0 selinuxfs 0:12 > | \_ kernel/debug 2e 0 debugfs 0:8 > \_ dev 15 4 devtmpfs 0:6 > | \_ shm 17 0 tmpfs 0:14 > | \_ pts 18 0 devpts 0:15 > | \_ hugepages 2b 0 hugetlbfs 0:27 > | \_ mqueue 2c 0 mqueue 0:11 > \_ run 19 1 tmpfs 0:16 > | \_ user/0 1b4 0 tmpfs 0:2d > \_ proc 14 1 proc 0:4 > | \_ sys/fs/binfmt_misc 2d 0 autofs 0:28 > \_ tmp 2f 7d0 tmpfs 0:29 > \_ var/cache/fscache 71 0 tmpfs 0:2a > \_ boot 74 0 ext4 8:15 > \_ home 74 0 ext4 8:15 > \_ var/lib/nfs/rpc_pipefs bf 0 rpc_pipefs 0:2b > \_ mnt 15b 5 tmpfs 0:2c > | \_ foo 164 0 tmpfs 0:2e > | \_ foo1 16d 0 tmpfs 0:2f > | \_ foo2 176 0 tmpfs 0:30 > | \_ foo3 17f 0 tmpfs 0:31 > | \_ foo4 188 1 tmpfs 0:32 > | \_ "" 191 0 tmpfs 0:33 > \_ afs 19a 2 afs 0:34 > \_ procyon.org.uk 1a3 0 afs 0:35 > \_ grand.central.org 1ac 0 afs 0:36 > > Signed-off-by: David Howells<dhowells@redhat.com> > --- > > samples/vfs/Makefile | 3 + > samples/vfs/test-mntinfo.c | 239 ++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 242 insertions(+) > create mode 100644 samples/vfs/test-mntinfo.c > diff --git a/samples/vfs/test-mntinfo.c b/samples/vfs/test-mntinfo.c > new file mode 100644 > index 000000000000..00fbefae98fa > --- /dev/null > +++ b/samples/vfs/test-mntinfo.c > +/* > + * Display a mount and then recurse through its children. > + */ > +static void display_mount(unsigned int mnt_id, unsigned int depth, char *path) > +{ > + struct fsinfo_mount_child *children; > + struct fsinfo_mount_info info; > + struct fsinfo_ids ids; > + unsigned int d; > + size_t ch_size, p_size; > + int i, n, s; > + > + get_attr(mnt_id, FSINFO_ATTR_MOUNT_INFO, &info, sizeof(info)); > + get_attr(mnt_id, FSINFO_ATTR_IDS, &ids, sizeof(ids)); > + if (depth > 0) > + printf("%s", tree_buf); > + > + s = strlen(path); > + printf("%s", !s ? "\"\"" : path); > + if (!s) > + s += 2; > + s += depth; > + if (s < 40) > + s = 40 - s; > + else > + s = 1; > + printf("%*.*s", s, s, ""); > + > + printf("%8x %8x %s %x:%x", > + info.mnt_id, info.notify_counter, > + ids.f_fs_name, ids.f_dev_major, ids.f_dev_minor); > + putchar('\n'); > + > + children = get_attr_alloc(mnt_id, FSINFO_ATTR_MOUNT_CHILDREN, 0, &ch_size); > + n = ch_size / sizeof(children[0]) - 1; > + > + bar_buf[depth + 1] = '|'; > + if (depth > 0) { > + tree_buf[depth - 4 + 1] = bar_buf[depth - 4 + 1]; > + tree_buf[depth - 4 + 2] = ' '; > + } > + > + tree_buf[depth + 0] = ' '; > + tree_buf[depth + 1] = '\\'; > + tree_buf[depth + 2] = '_'; > + tree_buf[depth + 3] = ' '; > + tree_buf[depth + 4] = 0; > + d = depth + 4; > + > + for (i = 0; i < n; i++) { > + if (i == n - 1) > + bar_buf[depth + 1] = ' '; > + path = get_attr_alloc(mnt_id, FSINFO_ATTR_MOUNT_SUBMOUNT, i, &p_size); > + display_mount(children[i].mnt_id, d, path + 1); > + free(path); > + } > + > + free(children); > + if (depth > 0) { > + tree_buf[depth - 4 + 1] = '\\'; > + tree_buf[depth - 4 + 2] = '_'; > + } > + tree_buf[depth] = 0; > +} > + > +/* > + * Find the ID of whatever is at the nominated path. > + */ > +static unsigned int lookup_mnt_by_path(const char *path) > +{ > + struct fsinfo_mount_info mnt; > + struct fsinfo_params params = { > + .request = FSINFO_ATTR_MOUNT_INFO, > + }; > + > + if (fsinfo(AT_FDCWD, path, ¶ms, &mnt, sizeof(mnt)) == -1) { > + perror(path); > + exit(1); > + } > + > + return mnt.mnt_id; > +} > + > +/* > + * > + */ > +int main(int argc, char **argv) > +{ > + unsigned int mnt_id; > + char *path; > + bool use_mnt_id = false; > + int opt; > + > + while ((opt = getopt(argc, argv, "M"))) { > + switch (opt) { > + case 'M': > + use_mnt_id = true; > + continue; > + } > + break; > + } > + > + argc -= optind; > + argv += optind; > + > + switch (argc) { > + case 0: > + mnt_id = lookup_mnt_by_path("/"); > + path = "ROOT"; > + break; > + case 1: > + path = argv[0]; > + if (use_mnt_id) { > + mnt_id = strtoul(argv[0], NULL, 0); > + break; > + } > + > + mnt_id = lookup_mnt_by_path(argv[0]); > + break; > + default: > + printf("Format: test-mntinfo\n"); > + printf("Format: test-mntinfo <path>\n"); > + printf("Format: test-mntinfo -M <mnt_id>\n"); > + exit(2); > + } > + > + display_mount(mnt_id, 0, path); > + return 0; > +} > >
diff --git a/samples/vfs/Makefile b/samples/vfs/Makefile index 3c542d3b9479..d377b1f7de79 100644 --- a/samples/vfs/Makefile +++ b/samples/vfs/Makefile @@ -3,6 +3,7 @@ hostprogs-y := \ test-fsinfo \ test-fs-query \ test-fsmount \ + test-mntinfo \ test-statx # Tell kbuild to always build the programs @@ -10,6 +11,8 @@ always := $(hostprogs-y) HOSTCFLAGS_test-fsinfo.o += -I$(objtree)/usr/include HOSTLDLIBS_test-fsinfo += -lm +HOSTCFLAGS_test-mntinfo.o += -I$(objtree)/usr/include +HOSTLDLIBS_test-mntinfo += -lm HOSTCFLAGS_test-fs-query.o += -I$(objtree)/usr/include HOSTCFLAGS_test-fsmount.o += -I$(objtree)/usr/include diff --git a/samples/vfs/test-mntinfo.c b/samples/vfs/test-mntinfo.c new file mode 100644 index 000000000000..00fbefae98fa --- /dev/null +++ b/samples/vfs/test-mntinfo.c @@ -0,0 +1,239 @@ +/* Test the fsinfo() system call + * + * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +#define _GNU_SOURCE +#define _ATFILE_SOURCE +#include <stdbool.h> +#include <stdio.h> +#include <stdlib.h> +#include <stdint.h> +#include <string.h> +#include <unistd.h> +#include <ctype.h> +#include <errno.h> +#include <time.h> +#include <math.h> +#include <sys/syscall.h> +#include <linux/fsinfo.h> +#include <linux/socket.h> +#include <linux/fcntl.h> +#include <sys/stat.h> +#include <arpa/inet.h> + +#ifndef __NR_fsinfo +#define __NR_fsinfo -1 +#endif + +static __attribute__((unused)) +ssize_t fsinfo(int dfd, const char *filename, struct fsinfo_params *params, + void *buffer, size_t buf_size) +{ + return syscall(__NR_fsinfo, dfd, filename, params, buffer, buf_size); +} + +static char tree_buf[4096]; +static char bar_buf[4096]; + +/* + * Get an fsinfo attribute in a statically allocated buffer. + */ +static void get_attr(unsigned int mnt_id, enum fsinfo_attribute attr, + void *buf, size_t buf_size) +{ + struct fsinfo_params params = { + .at_flags = AT_FSINFO_MOUNTID_PATH, + .request = attr, + }; + char file[32]; + long ret; + + sprintf(file, "%u", mnt_id); + + memset(buf, 0xbd, buf_size); + + ret = fsinfo(AT_FDCWD, file, ¶ms, buf, buf_size); + if (ret == -1) { + fprintf(stderr, "mount-%s: %m\n", file); + exit(1); + } +} + +/* + * Get an fsinfo attribute in a dynamically allocated buffer. + */ +static void *get_attr_alloc(unsigned int mnt_id, enum fsinfo_attribute attr, + unsigned int Nth, size_t *_size) +{ + struct fsinfo_params params = { + .at_flags = AT_FSINFO_MOUNTID_PATH, + .request = attr, + .Nth = Nth, + }; + size_t buf_size = 4096; + char file[32]; + void *r; + long ret; + + sprintf(file, "%u", mnt_id); + + for (;;) { + r = malloc(buf_size); + if (!r) { + perror("malloc"); + exit(1); + } + memset(r, 0xbd, buf_size); + + ret = fsinfo(AT_FDCWD, file, ¶ms, r, buf_size); + if (ret == -1) { + fprintf(stderr, "mount-%s: %m\n", file); + exit(1); + } + + if (ret <= buf_size) { + *_size = ret; + break; + } + buf_size = (ret + 4096 - 1) & ~(4096 - 1); + } + + return r; +} + +/* + * Display a mount and then recurse through its children. + */ +static void display_mount(unsigned int mnt_id, unsigned int depth, char *path) +{ + struct fsinfo_mount_child *children; + struct fsinfo_mount_info info; + struct fsinfo_ids ids; + unsigned int d; + size_t ch_size, p_size; + int i, n, s; + + get_attr(mnt_id, FSINFO_ATTR_MOUNT_INFO, &info, sizeof(info)); + get_attr(mnt_id, FSINFO_ATTR_IDS, &ids, sizeof(ids)); + if (depth > 0) + printf("%s", tree_buf); + + s = strlen(path); + printf("%s", !s ? "\"\"" : path); + if (!s) + s += 2; + s += depth; + if (s < 40) + s = 40 - s; + else + s = 1; + printf("%*.*s", s, s, ""); + + printf("%8x %8x %s %x:%x", + info.mnt_id, info.notify_counter, + ids.f_fs_name, ids.f_dev_major, ids.f_dev_minor); + putchar('\n'); + + children = get_attr_alloc(mnt_id, FSINFO_ATTR_MOUNT_CHILDREN, 0, &ch_size); + n = ch_size / sizeof(children[0]) - 1; + + bar_buf[depth + 1] = '|'; + if (depth > 0) { + tree_buf[depth - 4 + 1] = bar_buf[depth - 4 + 1]; + tree_buf[depth - 4 + 2] = ' '; + } + + tree_buf[depth + 0] = ' '; + tree_buf[depth + 1] = '\\'; + tree_buf[depth + 2] = '_'; + tree_buf[depth + 3] = ' '; + tree_buf[depth + 4] = 0; + d = depth + 4; + + for (i = 0; i < n; i++) { + if (i == n - 1) + bar_buf[depth + 1] = ' '; + path = get_attr_alloc(mnt_id, FSINFO_ATTR_MOUNT_SUBMOUNT, i, &p_size); + display_mount(children[i].mnt_id, d, path + 1); + free(path); + } + + free(children); + if (depth > 0) { + tree_buf[depth - 4 + 1] = '\\'; + tree_buf[depth - 4 + 2] = '_'; + } + tree_buf[depth] = 0; +} + +/* + * Find the ID of whatever is at the nominated path. + */ +static unsigned int lookup_mnt_by_path(const char *path) +{ + struct fsinfo_mount_info mnt; + struct fsinfo_params params = { + .request = FSINFO_ATTR_MOUNT_INFO, + }; + + if (fsinfo(AT_FDCWD, path, ¶ms, &mnt, sizeof(mnt)) == -1) { + perror(path); + exit(1); + } + + return mnt.mnt_id; +} + +/* + * + */ +int main(int argc, char **argv) +{ + unsigned int mnt_id; + char *path; + bool use_mnt_id = false; + int opt; + + while ((opt = getopt(argc, argv, "M"))) { + switch (opt) { + case 'M': + use_mnt_id = true; + continue; + } + break; + } + + argc -= optind; + argv += optind; + + switch (argc) { + case 0: + mnt_id = lookup_mnt_by_path("/"); + path = "ROOT"; + break; + case 1: + path = argv[0]; + if (use_mnt_id) { + mnt_id = strtoul(argv[0], NULL, 0); + break; + } + + mnt_id = lookup_mnt_by_path(argv[0]); + break; + default: + printf("Format: test-mntinfo\n"); + printf("Format: test-mntinfo <path>\n"); + printf("Format: test-mntinfo -M <mnt_id>\n"); + exit(2); + } + + display_mount(mnt_id, 0, path); + return 0; +}
Implement a program to demonstrate mount listing using the new fsinfo() syscall, for example: # ./test-mntinfo ROOT 5d c ext4 8:12 \_ sys 13 8 sysfs 0:13 | \_ kernel/security 16 0 securityfs 0:7 | \_ fs/cgroup 1a 10 tmpfs 0:17 | | \_ unified 1b 0 cgroup2 0:18 | | \_ systemd 1c 0 cgroup 0:19 | | \_ freezer 20 0 cgroup 0:1d | | \_ cpu,cpuacct 21 0 cgroup 0:1e | | \_ memory 22 0 cgroup 0:1f | | \_ cpuset 23 0 cgroup 0:20 | | \_ hugetlb 24 0 cgroup 0:21 | | \_ net_cls,net_prio 25 0 cgroup 0:22 | | \_ blkio 26 0 cgroup 0:23 | | \_ perf_event 27 0 cgroup 0:24 | | \_ devices 28 0 cgroup 0:25 | | \_ rdma 29 0 cgroup 0:26 | \_ fs/pstore 1d 0 pstore 0:1a | \_ firmware/efi/efivars 1e 0 efivarfs 0:1b | \_ fs/bpf 1f 0 bpf 0:1c | \_ kernel/config 5a 0 configfs 0:10 | \_ fs/selinux 2a 0 selinuxfs 0:12 | \_ kernel/debug 2e 0 debugfs 0:8 \_ dev 15 4 devtmpfs 0:6 | \_ shm 17 0 tmpfs 0:14 | \_ pts 18 0 devpts 0:15 | \_ hugepages 2b 0 hugetlbfs 0:27 | \_ mqueue 2c 0 mqueue 0:11 \_ run 19 1 tmpfs 0:16 | \_ user/0 1b4 0 tmpfs 0:2d \_ proc 14 1 proc 0:4 | \_ sys/fs/binfmt_misc 2d 0 autofs 0:28 \_ tmp 2f 7d0 tmpfs 0:29 \_ var/cache/fscache 71 0 tmpfs 0:2a \_ boot 74 0 ext4 8:15 \_ home 74 0 ext4 8:15 \_ var/lib/nfs/rpc_pipefs bf 0 rpc_pipefs 0:2b \_ mnt 15b 5 tmpfs 0:2c | \_ foo 164 0 tmpfs 0:2e | \_ foo1 16d 0 tmpfs 0:2f | \_ foo2 176 0 tmpfs 0:30 | \_ foo3 17f 0 tmpfs 0:31 | \_ foo4 188 1 tmpfs 0:32 | \_ "" 191 0 tmpfs 0:33 \_ afs 19a 2 afs 0:34 \_ procyon.org.uk 1a3 0 afs 0:35 \_ grand.central.org 1ac 0 afs 0:36 Signed-off-by: David Howells <dhowells@redhat.com> --- samples/vfs/Makefile | 3 + samples/vfs/test-mntinfo.c | 239 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 242 insertions(+) create mode 100644 samples/vfs/test-mntinfo.c