Re: [REGRESSION] ntfs3: existing files/dirs with ':' in their name became inaccessible in 7.3 (ads on by default)

[Thorsten Leemhuis]

On 11/14/26 13:50, Clément Smagghe wrote:
>> Hi Konstantin,>>>> Since upgrading from 7.2.11 to 7.3.4, files and directories on an
>> ntfs3 volume whose name contains a colon are listed by readdir but can
>> no longer be looked up: stat/open/rename/unlink all fail with ENOENT.
>> Nothing changed on the volume or in my fstab; the only change is the
>> kernel. This is caused by commit be310476e886 ("fs/ntfs3: Add basic
>> support for alternative data streams"), merged for v7.3-rc1, which
>> enables the new 'ads' mount option by default.

Thx for the reports. This sounds a lot like a problem Hungyu Lin is
trying to fix with these patches:

[PATCH] fs/ntfs3: preserve colons in symlink targets
https://lore.kernel.org/all/20261029203457.59990-1-dennylin0707@xxxxxxxxx/

[PATCH] fs/ntfs3: preserve colons in volume labels
https://lore.kernel.org/all/20261029225856.1173-1-dennylin0707@xxxxxxxxx/

Please look into those -- and if your's is a different problem, please
report back.

Ciao, Thorsten

>> Example (the directory was created on Linux and was perfectly usable
>> with 7.2.11):
>>
>>   $ ls -1b "Game Soundtracks" | grep Reverse
>>   Reverse:\ 1999
>>   $ ls Rever*
>>   ls: cannot access 'Reverse: 1999': No such file or directory
>>   $ stat "Reverse: 1999"
>>   stat: cannot statx 'Reverse: 1999': No such file or directory
>>   $ mv "Reverse: 1999" "Reverse - 1999"
>>   mv: cannot stat 'Reverse: 1999': No such file or directory
>>
>> With 'ads' enabled, ntfs_nls_to_utf16() splits every lookup name at
>> the first ':' and treats the rest as a stream name, so "Reverse: 1999"
>> is looked up as stream " 1999" of a non-existent file "Reverse". The
>> real directory entry is never matched.
>>
>> Why I think this should be treated as a regression:
>>
>> 1. Userspace that worked on 7.2 breaks on 7.3 without any
>>    configuration change. Names with ':' are legal on NTFS (they exist
>>    on volumes written by Linux, by ntfs-3g, by macOS, by WSL, ...),
>>    and they are still returned by readdir, so the directory listing
>>    and the lookup now disagree with each other. Tools like ls, find,
>>    rsync or backup software report errors, and the files cannot even
>>    be renamed or deleted to work around it.
>>
>> 2. There is no obvious way out. The current mount line is:
>>
>>      /dev/sdb1 on /mnt/HDD_2TB_WD type ntfs3
>>      (rw,noatime,uid=1000,gid=1000,dmask=0000,fmask=0000,acl,
>>       iocharset=utf8,prealloc,ads)
>>
>>    'ads' is shown although it was never requested. Following
>>    Documentation/filesystems/ntfs3.rst ("You can use every mount option
>>    with no option"), I tried 'noads', which is rejected, because the
>>    parser only registers fsparam_flag("ads") and fsparam_bool("ads").
>>    The only way to get the old behaviour back is 'ads=0', which I only
>>    found by reading the commit message.
>>
>> 3. Silently enabling a new syntax that changes the meaning of an
>>    existing, valid file name is also a data safety concern: with a
>>    regular file "a" present, an application asking to create "a:b"
>>    now writes into a hidden stream of "a" instead of creating a new
>>    file.
>>
>> Could you please make 'ads' opt-in (default off), or at the very
>> least make lookup prefer an existing directory entry whose full name
>> contains ':' before interpreting the name as file:stream? It would
>> also help to accept 'noads' like the other options and document
>> 'ads=0' in ntfs3.rst.
>>
>> Workaround confirmed here: mounting with 'ads=0' makes the entries
>> accessible again.
>>
>> Environment:
>>   Linux version 7.3.4-arch1-1 (linux@archlinux) (gcc (GCC) 16.2.1
>>   20260810, GNU ld (GNU Binutils) 2.47) #1 SMP PREEMPT_DYNAMIC Wed,
>>   11 Nov 2026 19:02:39 +0000
>>   Arch Linux, x86_64
>>   Last good: 7.2.11 (Arch)   First bad: 7.3.4 (Arch)
>>   The Arch kernel carries no ntfs3 patches. I have not built mainline,
>>   but in v7.4-rc2 fs/ntfs3/super.c still sets opts->ads = 1 by default
>>   and has no "noads" parameter, so the behaviour is unchanged there.
>>   The kernel is tainted (OE) by out-of-tree nvidia and tuxedo laptop
>>   modules, which are unrelated to the filesystem path involved.
>>
>> fstab entry:
>>   UUID=717D6EE943D0AF06 /mnt/HDD_2TB_WD ntfs3 x-systemd.automount,uid=1000,gid=1000,fmask=000,dmask=000,noatime,exec,rw 0 0
>>
>> #regzbot introduced: be310476e886
>> #regzbot title: ntfs3: names containing ':' inaccessible since ADS support is enabled by default
>>
>> Thanks,
>> Clément Smagghe
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