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Date:   Mon, 10 May 2021 09:46:09 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Shyam Prasad <Shyam.Prasad@microsoft.com>
Cc:     Salvatore Bonaccorso <carnil@debian.org>,
        Paulo Alcantara <palcantara@suse.de>, pc <pc@cjr.nz>,
        "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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A: http://en.wikipedia.org/wiki/Top_post
Q: Were do I find info about this thing called top-posting?
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

A: No.
Q: Should I include quotations after my reply?

http://daringfireball.net/2007/07/on_top

On Sun, May 09, 2021 at 10:16:06AM +0000, Shyam Prasad wrote:
> 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.
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.12&id=a738c93fb1c17e386a09304b517b1c6b2a6a5a8b
> 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.

So, you need that a738c93fb1c1 ("cifs: Set CIFS_MOUNT_USE_PREFIX_PATH
flag on setting cifs_sb->prepath.") merged to where exactly?

> 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.

Can you submit this in a proper format (i.e. not dos line ends, and good
changelog and most importantly, YOUR signed off by on it saying that the
patch came through you?

Make this a 2 patch series please, and be specific as to what tree(s)
this needs to be backported to, and I will be glad to review it.

thnaks,

greg k-h