linux-kernel - Re: [PATCH v2 05/10] fs/ntfs3: Add attrib operations

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Date:   Fri, 28 Aug 2020 16:52:03 +0000
From:   Konstantin Komarov <almaz.alexandrovich@...agon-software.com>
To:     Mark Harmstone <mark@...mstone.com>,
        "viro@...iv.linux.org.uk" <viro@...iv.linux.org.uk>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>
CC:     Pali Rohár <pali@...nel.org>
Subject: Re: [PATCH v2 05/10] fs/ntfs3: Add attrib operations

From: Mark Harmstone <mark.harmstone@...il.com> On Behalf Of Mark Harmstone
Sent: Monday, August 24, 2020 7:14 PM
> 
> Hi Konstantin,
> 
> I have an interest in this - I wrote the Btrfs driver for Windows, which also had to deal with the issue of how to map NTFS concept to
> Linux xattrs. Unless there's a good reason, I think it'd be in everyone's interests if we used the same conventions.
> 
> You have four(!) different ways of referring to the attributes value, which seems a bit excessive. I suggest you just use
> user.DOSATTRIB - this should be in the user namespace as users can set e.g. the hidden flag on files at will. This also matches what my
> driver does, and what Samba does.
> 

Hi Mark! Thanks for the feedback. It's reasonable concern, but the open 
question is how to access those NTFS attributes which extend the DOS 
attributes. user.DOSATTRIB may be good for FAT32 as DOS attributes are stored in 8bit.
However, this does not apply to NTFS (32bit attributes).

> I also think it's a mistake to only expose user.DOSATTRIB to Samba - there's patches in Wine staging which would also benefit from
> this.
> 

Agreed. Will fix this in v4. We think historically this came from wrong reading of
"This extended attribute is explicitly hidden from smbd clients requesting an EA list."

> Also, unless I'm missing something there's a bug in ntfs_setxattr - the user shouldn't be able to clear the FILE_ATTRIBUTE_DIRECTORY
> flag on directories nor set it on files.
> 

Thanks! Fixed in v3.

> Thanks
> 
> Mark
>