linux-kernel - RE: [EXTERNAL] Re: [PATCH 4.19 013/247] cifs: Set CIFS_MOUNT_USE_PREFIX_PATH flag on setting cifs

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Date:   Mon, 19 Apr 2021 05:48:24 +0000
From:   Shyam Prasad <Shyam.Prasad@...rosoft.com>
To:     Salvatore Bonaccorso <carnil@...ian.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>, pc <pc@....nz>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Aurelien Aptel <aaptel@...e.com>,
        Steven French <Steven.French@...rosoft.com>,
        Sasha Levin <sashal@...nel.org>
Subject: RE: [EXTERNAL] Re: [PATCH 4.19 013/247] cifs: Set
 CIFS_MOUNT_USE_PREFIX_PATH flag on setting cifs_sb->prepath.

<Including Paulo in this email thread>

Hi Salvatore,

Attached is a proposed fix from Paulo for older kernels. 
Can you please confirm that this works for you too? 

Regards,
Shyam

-----Original Message-----
From: Salvatore Bonaccorso <salvatore.bonaccorso@...il.com> On Behalf Of Salvatore Bonaccorso
Sent: Sunday, April 18, 2021 6:11 PM
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Shyam Prasad <Shyam.Prasad@...rosoft.com>; linux-kernel@...r.kernel.org; stable@...r.kernel.org; Aurelien Aptel <aaptel@...e.com>; Steven French <Steven.French@...rosoft.com>; Sasha Levin <sashal@...nel.org>
Subject: Re: [EXTERNAL] Re: [PATCH 4.19 013/247] cifs: Set CIFS_MOUNT_USE_PREFIX_PATH flag on setting cifs_sb->prepath.

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://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%
> > > > 2Fwiki.samba.org%2Findex.php%2FLinuxCIFS_troubleshooting%23Enabl
> > > > ing_Debugging&amp;data=04%7C01%7CShyam.Prasad%40microsoft.com%7C
> > > > 3f7f5a39dd974cacf6aa08d902674040%7C72f988bf86f141af91ab2d7cd011d
> > > > b47%7C1%7C0%7C637543465194151840%7CUnknown%7CTWFpbGZsb3d8eyJWIjo
> > > > iMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C10
> > > > 00&amp;sdata=nH2tcSzqFzzqLZ2RIARR008%2FuvBEdDHEnjKpVXhzIdk%3D&am
> > > > p;reserved=0
> > > 
> > > 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

Download attachment "0001-cifs-fix-prefix-path-in-dfs-mounts.patch" of type "application/octet-stream" (1160 bytes)