linux-kernel - Re: [PATCH v2] CIFS: Print message when attempting a mount

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Message-ID: <CAH2r5ms814MUNWVZNfCTuSO2LQZsmCs5N1nwgdVuhxtMctRE3Q@mail.gmail.com>
Date:   Tue, 2 Oct 2018 15:35:49 -0500
From:   Steve French <smfrench@...il.com>
To:     rfreire@...hat.com
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Steve French <sfrench@...ba.org>,
        CIFS <linux-cifs@...r.kernel.org>,
        Pavel Shilovsky <piastryyy@...il.com>
Subject: Re: [PATCH v2] CIFS: Print message when attempting a mount

I noticed that on at least the first system I looked at (Ubuntu 18.04)
it defaults to KERN_WARNING (ie 4) so wouldn't have shown a KERN_INFO
which is level 6 (as the mount example from ext4) by default
or the xfs_notice (which is level 5)

https://elinux.org/Debugging_by_printing

On Tue, Oct 2, 2018 at 2:28 PM Rodrigo Freire <rfreire@...hat.com> wrote:
>
> Hi Steve,
>
> ----- Original Message -----
> > From: "Steve French" <smfrench@...il.com>
> > To: rfreire@...hat.com
> > Cc: "LKML" <linux-kernel@...r.kernel.org>, "Steve French"
> > <sfrench@...ba.org>, "CIFS" <linux-cifs@...r.kernel.org>, "Pavel Shilovsky"
> > <piastryyy@...il.com>
> > Sent: Tuesday, October 2, 2018 4:17:02 PM
> > Subject: Re: [PATCH v2] CIFS: Print message when attempting a mount
> >
> > Are you sure that these aren't logged by the automounter (for ext4,
> > xfs etc.). When I looked in my dmesg logs I didn't find matching log
> > entries in the file systems themselves. Do you have an example?
>
> I'm positive about it. Check it out:
>
> [rfreire@rf ~]$ cd git/upstream/fs/ext4/
> [rfreire@rf ext4]$
> [rfreire@rf ext4]$
> [rfreire@rf ext4]$ grep -r "mounted filesystem with"
> super.c:                ext4_msg(sb, KERN_INFO, "mounted filesystem with%s. "
>
>
> [rfreire@rf ext4]$ dmesg | grep mount
> [   21.550897] EXT4-fs (dm-1): mounted filesystem with ordered data mode. Opts: (null)
> [   22.216213] EXT4-fs (dm-1): re-mounted. Opts: discard
> [   22.598267] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts: (null)
> [   22.605225] EXT4-fs (sdc): mounted filesystem without journal. Opts: discard
> [   24.029161] EXT4-fs (dm-2): mounted filesystem with ordered data mode. Opts: (null)
> [   24.047777] EXT4-fs (dm-4): mounted filesystem without journal. Opts: (null)
>
> XFS sample dmesg (from https://www.reddit.com/r/archlinux/comments/40b9r9/xfs_partition_is_mounted_during_boot_and_then/):
>
> [ 2.764491] XFS (sdb1): Mounting V5 Filesystem
> [ 3.200886] XFS (sdb1): Ending clean mount
> [ 5.384218] XFS (sdb1): Unmounting Filesystem
>
> Relevant code:
>
> [rfreire@rf ~]$ cd ../xfs
>
> [rfreire@rf xfs]$ grep "Mounting V" *.c
> xfs_log.c:              xfs_notice(mp, "Mounting V%d Filesystem",
>
>
> > On the idea of adding cifsFYI logging here - I slightly prefer using
> > ftrace (trace-cmd, ie dynamic tracing) so there is less overhead and
> > easier to turn on/off following the example of xfs, f2fs, nfs, nfsd
> > etc.
>
> Remember that cifsFYI already exists; I just moved it inside a if clause
> to print it only when running under debug. (they way it is originally).
>
> > On Tue, Oct 2, 2018 at 6:57 AM Rodrigo Freire <rfreire@...hat.com> wrote:
> > >
> > > Currently, no messages are printed when mounting a CIFS filesystem and
> > > no debug configuration is enabled.
> > >
> > > However, a CIFS mount information is valuable when troubleshooting
> > > and/or forensic analyzing a system and finding out if was a CIFS
> > > endpoint mount attempted.
> > >
> > > Other filesystems such as XFS, EXT* does issue a printk() when mounting
> > > their filesystems.
>
>
> > --
> > Thanks,
>
> Thank You! o/



-- 
Thanks,

Steve