linux-kernel - Re: [PATCH 11/11] fs/ntfs3: Taking DOS names into account during link counting

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Date: Thu, 18 Apr 2024 08:31:40 +0200
From: Johan Hovold <johan@...nel.org>
To: Konstantin Komarov <almaz.alexandrovich@...agon-software.com>
Cc: ntfs3@...ts.linux.dev, LKML <linux-kernel@...r.kernel.org>,
	Linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>,
	Anton Altaparmakov <anton@...era.com>
Subject: Re: [PATCH 11/11] fs/ntfs3: Taking DOS names into account during
 link counting

On Wed, Apr 17, 2024 at 04:10:59PM +0300, Konstantin Komarov wrote:
> When counting and checking hard links in an ntfs file record,
> 
>    struct MFT_REC {
>      struct NTFS_RECORD_HEADER rhdr; // 'FILE'
>      __le16 seq;        // 0x10: Sequence number for this record.
>  >>  __le16 hard_links;    // 0x12: The number of hard links to record.
>      __le16 attr_off;    // 0x14: Offset to attributes.
>    ...
> 
> the ntfs3 driver ignored short names (DOS names), causing the link count
> to be reduced by 1 and messages to be output to dmesg.

I also reported seeing link counts being reduced by 2:

[   78.307412] ntfs3: nvme0n1p3: ino=34e6, Correct links count -> 1 (3).
[   78.307843] ntfs3: nvme0n1p3: ino=5bb23, Correct links count -> 1 (2).
[   78.308509] ntfs3: nvme0n1p3: ino=5c722, Correct links count -> 1 (2).
[   78.310018] ntfs3: nvme0n1p3: ino=5d761, Correct links count -> 1 (2).
[   78.310717] ntfs3: nvme0n1p3: ino=33d18, Correct links count -> 1 (3).
[   78.311179] ntfs3: nvme0n1p3: ino=5d75b, Correct links count -> 1 (3).
[   78.311605] ntfs3: nvme0n1p3: ino=5c708, Correct links count -> 1 (3).

 - https://lore.kernel.org/all/Zhz_axTjkJ6Aqeys@hovoldconsulting.com/

Are you sure there are not further issues with this code?

> For Windows, such a situation is a minor error, meaning chkdsk does not 
> report
> errors on such a volume, and in the case of using the /f switch, it silently
> corrects them, reporting that no errors were found. This does not affect
> the consistency of the file system.
> 
> Nevertheless, the behavior in the ntfs3 driver is incorrect and
> changes the content of the file system. This patch should fix that.

This patch is white space damaged and does not apply.

> PS: most likely, there has been a confusion of concepts
> MFT_REC::hard_links and inode::__i_nlink.

I'd also expect a Fixes and CC stable tag here.

And as this patch does not seem to depend on the rest of the series it
should go first (along with any other bug fixes).

> Signed-off-by: Konstantin Komarov <almaz.alexandrovich@...agon-software.com>

Johan