when specifying multiple types, mount will mount

when specifying multiple types, mount will mount

[Benno Schulenberg]

Hi,

Current mount (2.25) will always mount a device when more
than one type is given in a comma-separated list.  Older mount
(2.17.2 for example) would not not do that but error out.

For example, /dev/sda2 is of type ext4, but we are playing dumb,
to see what mount will say:

$ sudo ./mount /dev/sda2 /place -t btrfs
lt-mount: /dev/sda2: can't read superblock

$ sudo ./mount /dev/sda2 /place -t msdos
lt-mount: wrong fs type, bad option, bad superblock on /dev/sda2,
       missing codepage or helper program, or other error

       In some cases useful info is found in syslog - try
       dmesg | tail or so.

$ sudo ./mount /dev/sda2 /place -t btrfs,msdos

$ ./mount | grep sda2
/dev/sda2 on /place type ext4 (rw)

I find this surprising.  If -t does not support a comma-separated
list, it should report an error.  If it does, it should, IMO, only
try the specified types and not any others.

Benno

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Re: when specifying multiple types, mount will mount

[Karel Zak]

On Thu, Jul 24, 2014 at 10:31:11PM +0200, Benno Schulenberg wrote:
> Current mount (2.25) will always mount a device when more
> than one type is given in a comma-separated list.  Older mount
> (2.17.2 for example) would not not do that but error out.

 We want to support list-of-types in fstab and on command line.

> For example, /dev/sda2 is of type ext4, but we are playing dumb,
> to see what mount will say:
> 
> $ sudo ./mount /dev/sda2 /place -t btrfs
> lt-mount: /dev/sda2: can't read superblock
> 
> $ sudo ./mount /dev/sda2 /place -t msdos
> lt-mount: wrong fs type, bad option, bad superblock on /dev/sda2,
>        missing codepage or helper program, or other error
> 
>        In some cases useful info is found in syslog - try
>        dmesg | tail or so.
> 
> $ sudo ./mount /dev/sda2 /place -t btrfs,msdos

this is bug, it continues with /{proc,etc}/filesystems when no found
anything useful in the list.

> $ ./mount | grep sda2
> /dev/sda2 on /place type ext4 (rw)
> 
> I find this surprising.  If -t does not support a comma-separated
> list, it should report an error.  If it does, it should, IMO, only
> try the specified types and not any others.

 yes, I'm just working on patch and regression test for all -t
 use-cases.

    Karel


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

Re: when specifying multiple types, mount will mount

[Karel Zak]

On Fri, Jul 25, 2014 at 10:32:16AM +0200, Karel Zak wrote:
> > I find this surprising.  If -t does not support a comma-separated
> > list, it should report an error.  If it does, it should, IMO, only
> > try the specified types and not any others.
> 
>  yes, I'm just working on patch and regression test for all -t
>  use-cases.

 Fixed, git pull.

    Karel

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