Messages in this thread | | | Subject | Re: [PATCH v2] CIFS: Print message when attempting a mount | From | Steve French <> | Date | Sat, 6 Oct 2018 12:13:20 -0500 |
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Comparing what other file systems print to dmesg at mount time is interesting - just tried it for four file systems, two log nothing by default, two log something. See below.
BTRFS:
root@smf-Thinkpad-P51:~/# mount /btrfs root@smf-Thinkpad-P51:~/c# dmesg [96283.701117] BTRFS info (device mmcblk0p1): disk space caching is enabled [96283.701121] BTRFS info (device mmcblk0p1): has skinny extents [96283.708477] BTRFS info (device mmcblk0p1): enabling ssd optimizations
EXT4:
root@smf-Thinkpad-P51:~# mount /dev/nvme0n1p6 /ext4 root@smf-Thinkpad-P51:~# dmesg [96654.422038] EXT4-fs (nvme0n1p6): mounted filesystem with ordered data mode. Opts: (null)
VFAT:
root@smf-Thinkpad-P51:~# mount /dev/nvme0n1p1 /fat root@smf-Thinkpad-P51:~# dmesg root@smf-Thinkpad-P51:~#
NFS (it logs messages first time the module is loaded, for the id_resolver, but not for the mount):
root@smf-Thinkpad-P51:~# mount -t nfs localhost:/nfsexport /nfs root@smf-Thinkpad-P51:~# dmesg root@smf-Thinkpad-P51:~#
On 10/02/2018 04:53 PM, Rodrigo Freire wrote: > Hi hi again Steve \o > > I do see potential for a ftrace rewrite for the cifs_dbg messages. > > But for the original post, I am aiming for a message to be printed > and found in dmesg, helping to correlate and troubleshoot events in > production systems. > > So given the debugging nature of ftrace, this is not of help for my > patch request. > > So, ACK for v2, using cifs_dbg(VFS) which actually translates to a > pr_warn(), or request a V3 using pr_info() (which I am absolutely fine > with) or...? > > Let me know. > > I appreciate your time and review! > > - RF. > > ----- Original Message ----- > >> From: "Steve French" <smfrench@gmail.com> >> To: rfreire@redhat.com >> Cc: "LKML" <linux-kernel@vger.kernel.org>, "Steve French" >> <sfrench@samba.org>, "CIFS" <linux-cifs@vger.kernel.org>, "Pavel Shilovsky" >> <piastryyy@gmail.com> >> Sent: Tuesday, October 2, 2018 6:25:46 PM >> Subject: Re: [PATCH v2] CIFS: Print message when attempting a mount >> It is an interesting question - my gut reaction is that messages that >> need more immediate attention should be logged as KERN_ERR (similar to >> cifs_dbg(VFS ...) but given how easy it is now to use dynamic tracing >> and better to read, if a developer would need it ... probably best to >> use ftrace (trace-cmd). Note that xfs has more than 570 (!) dynamic >> trace point callouts now vs. fewer than 30 for xfs_notice >> On Tue, Oct 2, 2018 at 4:20 PM Rodrigo Freire <rfreire@redhat.com> wrote: >>> Hi Steve o/ >>> >>> I personally like more a pr_info() instead of a cifs_dbg (which wraps to a >>> pr_warn). But in order to keep in line with the general CIFS coding style >>> I stuck to cifs_dbg >>> >>> But I would happily rewrite the cifs_dbg to pr_info a v3: That would be >>> good enough too. >>> >>> Ah for what is worth my test/target systems are CentOS/Red Hat Enterprise >>> Linux. >>> >>> Thoughts? >>> >>> Thanks! >>> >>> - RF. >>> >>> ----- Original Message ----- >>>> From: "Steve French" <smfrench@gmail.com> >>>> To: rfreire@redhat.com >>>> Cc: "LKML" <linux-kernel@vger.kernel.org>, "Steve French" >>>> <sfrench@samba.org>, "CIFS" <linux-cifs@vger.kernel.org>, "Pavel >>>> Shilovsky" >>>> <piastryyy@gmail.com> >>>> Sent: Tuesday, October 2, 2018 5:35:49 PM >>>> 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@redhat.com> wrote: >>>>> Hi Steve, >>>>> >>>>> ----- Original Message ----- >>>>>> From: "Steve French" <smfrench@gmail.com> >>>>>> To: rfreire@redhat.com >>>>>> Cc: "LKML" <linux-kernel@vger.kernel.org>, "Steve French" >>>>>> <sfrench@samba.org>, "CIFS" <linux-cifs@vger.kernel.org>, "Pavel >>>>>> Shilovsky" >>>>>> <piastryyy@gmail.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@redhat.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 >> -- >> Thanks, >> Steve
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