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Sender: Salvatore Bonaccorso <salvatore.bonaccorso@gmail.com>
Date:   Sun, 18 Apr 2021 14:41:10 +0200
From:   Salvatore Bonaccorso <carnil@debian.org>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Shyam Prasad <Shyam.Prasad@microsoft.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        Aurelien Aptel <aaptel@suse.com>,
        Steven French <Steven.French@microsoft.com>,
        Sasha Levin <sashal@kernel.org>
Subject: Re: [EXTERNAL] Re: [PATCH 4.19 013/247] cifs: Set
 CIFS_MOUNT_USE_PREFIX_PATH flag on setting cifs_sb->prepath.
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Hi Greg,

On Mon, Apr 12, 2021 at 10:01:33AM +0200, Greg Kroah-Hartman wrote:
> On Thu, Apr 08, 2021 at 01:41:05PM +0200, Salvatore Bonaccorso wrote:
> > Hi Shyam,
> > 
> > On Tue, Apr 06, 2021 at 05:01:17PM +0200, Salvatore Bonaccorso wrote:
> > > Hi,
> > > 
> > > On Tue, Apr 06, 2021 at 02:00:48PM +0000, Shyam Prasad wrote:
> > > > Hi Greg,
> > > > We'll need to debug this further to understand what's going on. 
> > > 
> > > Greg asked it the same happens with 5.4 as well, I do not know I was
> > > not able to test 5.4.y (yet) but only 5.10.y and 4.19.y.
> > > > 
> > > > Hi Salvatore,
> > > > Any chance that you'll be able to provide us the cifsFYI logs from the time of mount failure?
> > > > https://wiki.samba.org/index.php/LinuxCIFS_troubleshooting#Enabling_Debugging
> > > 
> > > Please find it attached. Is this enough information?
> > > 
> > > The mentioned home DFS link 'home' is a DFS link to
> > > msdfs:SECONDHOST\REDACTED on a Samba host.
> > > 
> > > The mount is triggered as
> > > 
> > > mount -t cifs //HOSTIP/REDACTED/home /mnt --verbose -o username='REDACTED,domain=DOMAIN'
> > 
> > So I can confirm the issue is both present in 4.19.185 and 5.4.110
> > upstream (without any Debian patches applied, we do not anyway apply
> > any cifs related one on top of the respetive upstream version).
> > 
> > The issue is not present in 5.10.28.
> > 
> > So I think there are commits as dependency of a738c93fb1c1 ("cifs: Set
> > CIFS_MOUNT_USE_PREFIX_PATH flag on setting cifs_sb->prepath.") which
> > are required and not applied in the released before 5.10.y which make
> > introducing the regression.
> 
> Ok, I've dropped this from 5.4 and older kernel trees now, thanks for
> the report.

Thanks Greg! Shyam, Steven, now the commit was reverted for the older
brnaches. But did you got a chance to find why it breaks for the older
series?

Regards,
Salvatore