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SubjectRE: [EXTERNAL] Re: [PATCH 4.19 013/247] cifs: Set CIFS_MOUNT_USE_PREFIX_PATH flag on setting cifs_sb->prepath.
Hi Salvatore,

Thanks for reminding me. I had to do some reading to reply to this one.
The situation right now is this:
The patch "cifs: Set CIFS_MOUNT_USE_PREFIX_PATH flag on setting cifs_sb->prepath." has been reverted. Which means that the DFS bug which you originally faced will not be seen.

Hi Greg,

Here are the two patches which I'm referring to:
1. cifs: Set CIFS_MOUNT_USE_PREFIX_PATH flag on setting cifs_sb->prepath.
This fixed an issue when two cifs mount points shared a common prefix in the path which they mounted from the same server. The patch was marked for CC:stable considering that this fix can be important for some users.
However, there was a dependent change for DFS scenario, which is present in the Linus' mainline tree, but were not marked for CC:stable, so missing from the stable trees.
Due to the missing dependent changes, DFS users faced issues with pre-5.11 kernels, and this patch was reverted in the stable trees.

2. Due to a major change that went into the 5.11 kernel (the new mount API support), the code differs significantly, and the missing patch cannot be applied to pre-5.11 trees.
Hence, Paulo submitted the attached patch (cifs: fix prefix path in dfs mounts), which fixes this for pre-5.11 kernels.

I was referring to these two patches to be applied to all stable trees. Salvatore has verified that with both patches applied, the DFS scenario starts working again.
@Paulo Alcantara Please add if I missed something here.


-----Original Message-----
From: Salvatore Bonaccorso <> On Behalf Of Salvatore Bonaccorso
Sent: Saturday, May 8, 2021 6:52 PM
To: Greg Kroah-Hartman <>
Cc: Shyam Prasad <>; pc <>;;; Aurelien Aptel <>; Steven French <>; Sasha Levin <>
Subject: Re: [EXTERNAL] Re: [PATCH 4.19 013/247] cifs: Set CIFS_MOUNT_USE_PREFIX_PATH flag on setting cifs_sb->prepath.

Shyam, Paulo,

On Fri, Apr 23, 2021 at 09:42:35AM +0200, Greg Kroah-Hartman wrote:
> On Thu, Apr 22, 2021 at 03:36:07PM +0000, Shyam Prasad wrote:
> > Hi Salvatore and Santiago,
> >
> > Thanks for testing this out.
> >
> > @Greg Kroah-Hartman: The reverted patch used in combination with Paulo's fix seems to fix both use cases.
> > Can we have both these taken in on stable kernels? Paulo's patch is needed only for kernels 5.10 and older.
> I do not know what "both" is here at all.
> Please resubmit all of the needed commits in a format that I can apply
> them in, and I will be glad to review them and queue them up.
> Note, patches that are not in Linus's tree better be documented really
> really really really well for why that is not so...

Did you saw the ping from Greg? Otherwise I think the situation as it is now for the older stable series is probably just as fine as it is now with the repsective original commit reverted.

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