linux-kernel - Re: [PATCH v5 06/14] ntfs: update file operations

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20260120064207.GB3350@lst.de>
Date: Tue, 20 Jan 2026 07:42:07 +0100
From: Christoph Hellwig <hch@....de>
To: Namjae Jeon <linkinjeon@...nel.org>
Cc: Christoph Hellwig <hch@....de>, viro@...iv.linux.org.uk,
	brauner@...nel.org, tytso@....edu, willy@...radead.org,
	jack@...e.cz, djwong@...nel.org, josef@...icpanda.com,
	sandeen@...deen.net, rgoldwyn@...e.com, xiang@...nel.org,
	dsterba@...e.com, pali@...nel.org, ebiggers@...nel.org,
	neil@...wn.name, amir73il@...il.com, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, iamjoonsoo.kim@....com,
	cheol.lee@....com, jay.sim@....com, gunho.lee@....com,
	Hyunchul Lee <hyc.lee@...il.com>
Subject: Re: [PATCH v5 06/14] ntfs: update file operations

On Tue, Jan 20, 2026 at 02:11:24PM +0900, Namjae Jeon wrote:
> By modifying iomap_begin, it seems possible to implement it using
> iomap_seek_hole/data without introducing a new IOMAP_xxx type.

Note that you can also use different iomap ops for different operations
if needed.

> Since NTFS does not support multiple unwritten extents, all
> pre-allocated regions must, in principle, be treated as DATA, not
> HOLE. However, in the current implementation, region #2 is mapped as
> IOMAP_UNWRITTEN, so iomap_seek_data incorrectly interprets this region
> as a hole. It would be better to map region #2 as IOMAP_MAPPED for the
> seek operation.

So basically it optimizes for the case of appending on the end.

Can you add the above to a code comment where you set IOMAP_UNWRITTEN?