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[78.151.217.120]) by smtp.gmail.com with ESMTPSA id p16sm37262352wrg.49.2019.06.05.05.22.13 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Wed, 05 Jun 2019 05:22:13 -0700 (PDT) From: Alan Jenkins Subject: Re: [PATCH 10/25] vfs: fsinfo sample: Mount listing program [ver #13] To: David Howells , viro@zeniv.linux.org.uk Cc: raven@themaw.net, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, mszeredi@redhat.com References: <155905626142.1662.18430571708534506785.stgit@warthog.procyon.org.uk> <155905634517.1662.7843563955043166854.stgit@warthog.procyon.org.uk> Message-ID: <9eeb6b39-c4a1-6e3d-246a-e1cf97d84b33@gmail.com> Date: Wed, 5 Jun 2019 13:22:12 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <155905634517.1662.7843563955043166854.stgit@warthog.procyon.org.uk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-GB Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > --- > > 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 \n"); > + printf("Format: test-mntinfo -M \n"); > + exit(2); > + } > + > + display_mount(mnt_id, 0, path); > + return 0; > +} > >