lkml.org 
[lkml]   [2017]   [Nov]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 3/3] autofs - fix AT_NO_AUTOMOUNT not being honored
    From
    Date
    On 23/11/17 10:46, Ian Kent wrote:
    > On 23/11/17 10:21, NeilBrown wrote:
    >> On Thu, Nov 23 2017, Ian Kent wrote:
    >>
    >>>
    >>> Hey Neil, I'm looking at this again because RH QE have complained about
    >>> a regression test failing with a kernel that has this change.
    >>>
    >>> Maybe I'm just dumb but I though a "find <base directory> <options>"
    >>> would, well, just look at the contents below <base directory> but an
    >>> strace shows that it reads and calls fstatat() on "every entry in the
    >>> mount table" regardless of the path.
    >>
    >> weird ... I can only get find to look at the mount table if given the
    >> -fstyp option, and even then it doesn't fstatat anything that isn't in
    >> the tree it is searching.
    >
    > It's probably the -xautofs (exclude autofs fs'es) that was used in
    > the test that requires reading the mount table to get info about
    > excluding autofs mounts but the fstatat() on all the entries,
    > regardless of path, that was a surprise to me.
    >
    > find did use AT_SYMLINK_NOFOLLOW which historically behaved like
    > AT_NO_AUTOMOUNT.

    Check this simple reproducer out:

    [root@intel-mahobay-02 ~]# uname -r
    4.14.0-0.rc8.2.el7a.x86_64
    [root@intel-mahobay-02 ~]# cat /etc/exports
    /exportdir-bz1482065 *(rw,no_root_squash)
    [root@intel-mahobay-02 ~]# cat /etc/auto.master
    /- /etc/auto.direct
    [root@intel-mahobay-02 ~]# cat /etc/auto.direct
    /mnt/autofs/test localhost:/exportdir-bz1482065
    [root@intel-mahobay-02 ~]# ls /mnt/autofs/
    bz1482065 test
    [root@intel-mahobay-02 ~]# ls /exportdir-bz1482065
    bz1482065
    [root@intel-mahobay-02 ~]# find /mnt/autofs -xautofs -name '*bz1482065*'
    [root@intel-mahobay-02 ~]# find /mnt/autofs -xautofs -name '*bz1482065*'
    /mnt/autofs/bz1482065
    /mnt/autofs/test/bz1482065

    The first find mounts the direct mount /mnt/autofs/test/bz1482065 which causes the
    second to list /mnt/autofs/bz1482065 (not sure yet where this comes from, it must
    be a plain directory within /mnt/autofs) and the now mounted bind mount (ie. the
    localhost: host name in the map entry) /mnt/autofs/test/bz1482065.

    The strace is:
    execve("/usr/bin/find", ["find", "/mnt/autofs", "-xautofs", "-name", "*bz1482065*"], [/* 45 vars */]) = 0

    snip ...

    newfstatat(AT_FDCWD, "/mnt/autofs", {st_mode=S_IFDIR|0755, st_size=35, ...}, AT_SYMLINK_NOFOLLOW) = 0
    open("/etc/mtab", O_RDONLY|O_CLOEXEC) = 4
    futex(0x7efec9ba55b0, FUTEX_WAKE_PRIVATE, 2147483647) = 0
    fstat(4, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
    mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7efeca2ea000
    read(4, "sysfs /sys sysfs rw,seclabel,nos"..., 1024) = 1024
    read(4, "oup/net_cls,net_prio cgroup rw,n"..., 1024) = 1024
    read(4, "ges hugetlbfs rw,seclabel,relati"..., 1024) = 594
    read(4, "", 1024) = 0
    close(4) = 0
    munmap(0x7efeca2ea000, 4096) = 0
    newfstatat(AT_FDCWD, "/sys", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/proc", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/dev", {st_mode=S_IFDIR|0755, st_size=3280, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/kernel/security", {st_mode=S_IFDIR|0755, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/dev/shm", {st_mode=S_IFDIR|S_ISVTX|0777, st_size=40, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/dev/pts", {st_mode=S_IFDIR|0755, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/run", {st_mode=S_IFDIR|0755, st_size=1020, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/fs/cgroup", {st_mode=S_IFDIR|0755, st_size=340, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/fs/cgroup/systemd", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/fs/pstore", {st_mode=S_IFDIR|0750, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/fs/cgroup/blkio", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/fs/cgroup/cpu,cpuacct", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/fs/cgroup/pids", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/fs/cgroup/net_cls,net_prio", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/fs/cgroup/devices", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/fs/cgroup/freezer", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/fs/cgroup/perf_event", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/fs/cgroup/cpuset", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/fs/cgroup/memory", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/fs/cgroup/hugetlb", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/kernel/config", {st_mode=S_IFDIR|0755, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/", {st_mode=S_IFDIR|0555, st_size=4096, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/fs/selinux", {st_mode=S_IFDIR|0755, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/proc/sys/fs/binfmt_misc", {st_mode=S_IFDIR|0755, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/sys/kernel/debug", {st_mode=S_IFDIR|0700, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/dev/mqueue", {st_mode=S_IFDIR|S_ISVTX|0777, st_size=40, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/dev/hugepages", {st_mode=S_IFDIR|0755, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/proc/fs/nfsd", {st_mode=S_IFDIR|0755, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/boot", {st_mode=S_IFDIR|0555, st_size=4096, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/home", {st_mode=S_IFDIR|0755, st_size=18, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/var/lib/nfs/rpc_pipefs", {st_mode=S_IFDIR|0555, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/run/user/0", {st_mode=S_IFDIR|0700, st_size=40, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/proc/sys/fs/binfmt_misc", {st_mode=S_IFDIR|0755, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
    newfstatat(AT_FDCWD, "/mnt/autofs/test", {st_mode=S_IFDIR|0755, st_size=23, ...}, AT_SYMLINK_NOFOLLOW) = 0
    fchdir(3) = 0
    close(3) = 0
    close(1) = 0
    close(2) = 0
    exit_group(0) = ?

    \
     
     \ /
      Last update: 2017-11-23 04:04    [W:5.977 / U:0.328 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site