util-linux-v2.25:mountpoint misnamed or bugged, and "-d" bugged

util-linux-v2.25:mountpoint misnamed or bugged, and "-d" bugged

[L A Walsh]

mountpoint doesn't detect file, device
or other inode mount points.

Also, the "-d" switch doesn't show the maj:min of the mounted
inode.  Of note: "-x" does show the maj:min of a remounted blockdev.

#reproduce (showing additional variant w/a char device)

cd /tmp
mkdir foo1
cd foo1
mkdir mnt
sudo mount tmpfs -t tmpfs mnt
touch mnt/file mnt_file mnt_null
sudo mknod mnt/null c 1 3
sudo mount --bind mnt/file mnt_file
sudo mount --bind mnt/null mnt_null
function is_mountedQ {
  if /usr/bin/mountpoint -q $1; then
    echo "$1 is a mount point"
  else
    echo "$1 is not a mount point"
  fi
}
is_mountedQ mnt_file
is_mountedQ mnt_null

------------
Note, -x does show a remounted dev:

Ishtar:/tmp/foo1/mnt> sudo mknod sda b 8 0
Ishtar:/tmp/foo1> ll mnt/sda
  brw-rw-r-- 1 8, 0 Apr 15 17:59 mnt/sda
Ishtar:/tmp/foo1> touch mnt_sda
Ishtar:/tmp/foo1> sudo mount --bind mnt/sda mnt_sda
Ishtar:/tmp/foo1> ll mnt_sda
  brw-rw-r-- 1 8, 0 Apr 15 17:59 mnt_sda
Ishtar:/tmp/foo1> mountpoint -x mnt_sda
  8:0

"mount |grep foo1" shows all the mount points:

Ishtar:/tmp/foo1> mount |grep foo1
tmpfs on /tmp/foo1/mnt type tmpfs (rw,relatime)
tmpfs on /tmp/foo1/mnt_file type tmpfs (rw,relatime)
tmpfs on /tmp/foo1/mnt_null type tmpfs (rw,relatime)
tmpfs on /tmp/foo1/mnt_sda type tmpfs (rw,relatime)

======
Side (or end) note:
Besides "mountpoint" handling mounted inodes, it **could**
be "more complete" by being enhanced to:

1) scan all names on its command line
2) scan all inodes in a directory
  or
3) scan all inodes recursively, starting at a directory

Re: util-linux-v2.25:mountpoint misnamed or bugged, and "-d" bugged

[Karel Zak]

On Sat, Apr 15, 2017 at 06:08:17PM -0700, L A Walsh wrote:
> 
> mountpoint doesn't detect file, device
> or other inode mount points.
> 
> Also, the "-d" switch doesn't show the maj:min of the mounted
> inode.  Of note: "-x" does show the maj:min of a remounted blockdev.

Version, distro, do you have classic mtab, etc, etc.... ?

> #reproduce (showing additional variant w/a char device)
> 
> cd /tmp
> mkdir foo1
> cd foo1
> mkdir mnt
> sudo mount tmpfs -t tmpfs mnt
> touch mnt/file mnt_file mnt_null
> sudo mknod mnt/null c 1 3
> sudo mount --bind mnt/file mnt_file
> sudo mount --bind mnt/null mnt_null
> function is_mountedQ {
>  if /usr/bin/mountpoint -q $1; then
>    echo "$1 is a mount point"
>  else
>    echo "$1 is not a mount point"
>  fi
> }
> is_mountedQ mnt_file
> is_mountedQ mnt_null

Works for me:

# cd /tmp               
# mkdir foo1            
# cd foo1               
# mkdir mnt             
# mount tmpfs -t tmpfs mnt
# touch mnt/file mnt_file mnt_null
# mknod mnt/null c 1 3  
# mount --bind mnt/file mnt_file
# mount --bind mnt/null mnt_null
# mountpoint mnt_null   
mnt_null is a mountpoint
# mountpoint mnt_file   
mnt_file is a mountpoint
 
# findmnt --submounts /tmp
TARGET               SOURCE       FSTYPE OPTIONS
/tmp                 tmpfs        tmpfs  rw,nosuid,nodev
├─/tmp/foo1/mnt      tmpfs        tmpfs  rw,relatime
├─/tmp/foo1/mnt_file tmpfs[/file] tmpfs  rw,relatime
└─/tmp/foo1/mnt_null tmpfs[/null] tmpfs  rw,relatime


    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

Re: util-linux-v2.25:mountpoint misnamed or bugged, and "-d" bugged

[Karel Zak]

On Wed, May 10, 2017 at 11:47:46AM +0200, Karel Zak wrote:
> On Sat, Apr 15, 2017 at 06:08:17PM -0700, L A Walsh wrote:
> > 
> > mountpoint doesn't detect file, device
> > or other inode mount points.
> > 
> > Also, the "-d" switch doesn't show the maj:min of the mounted
> > inode.  Of note: "-x" does show the maj:min of a remounted blockdev.
> 
> Version, distro, do you have classic mtab, etc, etc.... ?

Ah, now I see v2.25 in the subject. Sorry. My test is with v2.28 and
current git tree.

        Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com