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.. SPDX-License-Identifier: GPL-2.0
=================================
The Linux NTFS filesystem driver
=================================
.. Table of contents
- Overview
- Utilities support
- Linux file attributes
- Supported mount options
Overview
========
NTFS is a Linux kernel filesystem driver that provides full read and write
support for NTFS volumes. It is designed for high performance, modern
kernel infrastructure (iomap, folio), and stable long-term maintenance.
Utilities support
=================
The NTFS utilities project, called ntfsprogs-plus, provides mkfs.ntfs,
fsck.ntfs, and other related tools (e.g., ntfsinfo, ntfsclone, etc.) for
creating, checking, and managing NTFS volumes. These utilities can be used
for filesystem testing with xfstests as well as for recovering corrupted
NTFS devices.
The project is available at:
https://github.com/ntfsprogs-plus/ntfsprogs-plus
Linux file attributes
=====================
The driver supports lsattr(1) and chattr(1). Immutable, append-only, nodump
and noatime are stored in a private ``$LINUXFLAGS`` extended attribute within the
standard NTFS ``$EA``/``$EA_INFORMATION`` attributes. Its value is a
32-bit little-endian bitmask: bit 0 is immutable, bit 1 is append-only,
bit 2 is nodump, and bit 3 is noatime. Unknown bits are preserved when updating
the flags; the entry is removed when the entire value becomes zero. These settings
survive inode eviction, unmount and reboot. Direct writes to this EA
through setxattr(2) or removexattr(2) are rejected; use chattr(1) instead.
The noatime attribute (``chattr +A``) suppresses automatic access-time
updates for the inode, including when mounted with ``strictatime``. It
applies to directories as well as files, but is not inherited by newly
created children. Use ``chattr -A`` to restore the mount's access-time policy.
System metadata files and files protected by the ``sys_immutable`` mount
option cannot have their immutable protection cleared with chattr(1).
Protection derived solely from the mount option is not stored in the EA.
Case folding is reported according to the mount options and cannot be
configured per file. Compression and encryption are reported but cannot
be changed through chattr(1).
These Linux flags are enforced by Linux. Storing them in an NTFS EA does
not make Windows enforce immutable, append-only, nodump or noatime semantics.
Supported mount options
=======================
The NTFS driver supports the following mount options:
======================= ====================================================
iocharset=name Character set to use for converting between
the encoding is used for user visible filename and
16 bit Unicode characters.
nls=name Deprecated option. Still supported but please use
iocharset=name in the future.
uid=
gid=
umask= Provide default owner, group, and access mode mask.
These options work as documented in mount(8). By
default, the files/directories are owned by root
and he/she has read and write permissions, as well
as browse permission for directories. No one else
has any access permissions. I.e. the mode on all
files is by default rw------- and
for directories rwx------, a consequence of
the default fmask=0177 and dmask=0077.
Using a umask of zero will grant all permissions to
everyone, i.e. all files and directories will have
mode rwxrwxrwx.
fmask=
dmask= Instead of specifying umask which applies both to
files and directories, fmask applies only to files
and dmask only to directories.
showmeta=<BOOL>
show_sys_files=<BOOL> If show_sys_files is specified, show the system
files in directory listings. Otherwise the default
behaviour is to hide the system files.
Note that even when show_sys_files is specified,
"$MFT" will not be visible due to bugs/mis-features
in glibc. Further, note that irrespective of
show_sys_files, all files are accessible by name,
i.e. you can always do "ls -l \$UpCase" for example
to specifically show the system file containing
the Unicode upcase table.
case_sensitive=<BOOL> If case_sensitive is specified, treat all filenames
as case sensitive and create file names in
the POSIX namespace (default behavior). Note,
the Linux NTFS driver will never create short
filenames and will remove them on rename/delete of
the corresponding long file name. Note that files
remain accessible via their short file name, if it
exists.
nocase=<BOOL> If nocase is specified, treat filenames
case-insensitively.
disable_sparse=<BOOL> If disable_sparse is specified, creation of sparse
regions, i.e. holes, inside files is disabled for
the volume (for the duration of this mount only).
By default, creation of sparse regions is enabled,
which is consistent with the behaviour of
traditional Unix filesystems.
errors=opt Specify NTFS behavior on critical errors: panic,
remount the partition in read-only mode or
continue without doing anything (default behavior).
mft_zone_multiplier= Set the MFT zone multiplier for the volume (this
setting is not persistent across mounts and can be
changed from mount to mount but cannot be changed
on remount). Values of 1 to 4 are allowed, 1 being
the default. The MFT zone multiplier determines
how much space is reserved for the MFT on the
volume. If all other space is used up, then the
MFT zone will be shrunk dynamically, so this has no
impact on the amount of free space. However, it
can have an impact on performance by affecting
fragmentation of the MFT. In general use the
default. If you have a lot of small files then use
a higher value. The values have the following
meaning:
===== =================================
Value MFT zone size (% of volume size)
===== =================================
1 12.5%
2 25%
3 37.5%
4 50%
===== =================================
Note this option is irrelevant for read-only mount.
preallocated_size= Set preallocated size to optimize runlist merge
overhead with small chunck size.(64KB size by
default)
acl=<BOOL> Enable POSIX ACL support. When specified, POSIX
ACLs stored in extended attributes are enforced.
Default is off. Requires kernel config
NTFS_FS_POSIX_ACL enabled.
sys_immutable=<BOOL> Make NTFS system files (e.g. $MFT, $LogFile,
$Bitmap, $UpCase, etc.) immutable to user initiated
modifications for extra safety. Default is off.
nohidden=<BOOL> Hide files and directories marked with the Windows
"hidden" attribute. By default hidden items are
shown.
hide_dot_files=<BOOL> Hide names beginning with a dot ("."). By default
dot files are shown. When enabled, files and
directories created with a leading '.' will be
hidden from directory listings.
windows_names=<BOOL> Refuse creation/rename of files with characters or
reserved device names disallowed on Windows (e.g.
CON, NUL, AUX, COM1, LPT1, etc.). Default is off.
discard=<BOOL> Issue block device discard for clusters freed on
file deletion/truncation to inform underlying
storage.
native_symlink=raw|rel Configure how absolute symbolic links and mount
points (junctions) are handled. Under "raw"
(default), the absolute target path is returned
as-is without translation. Under "rel", it is
rewritten as a relative path anchored at
the volume root.
symlink=wsl|native Configure how symbolic links are created. Under
"wsl" (default), WSL (Windows Subsystem for
Linux) compatible symlinks are created. Under
"native", Windows native symbolic links are
created.
streams_interface= Select the named-stream pathname interface:
"none" (default) treats ':' as an ordinary filename
character, while "windows" interprets the final
component of a path such as "file:stream" as a named
$DATA stream. In "windows" mode, filenames containing
':' are hidden from directory listings and cannot be
addressed through the pathname interface. Only the
file:stream form is recognized. Typed forms such
as file::$DATA and file:stream:$DATA are not
supported. The ioctl interface is available in both
modes. The base file or directory must already exist
before a pathname stream can be created. Creating
file:stream does not create file. Removing a stream
while it is open fails with -EBUSY. Removing the base
file while a stream is open detaches the stream from
the namespace; NTFS has no orphan-stream list, so a
crash can leave that stream's data unreachable on
disk.
======================= ====================================================
Named-stream ioctls
===================
The named-stream ioctl interface is available regardless of
streams_interface. Open the base regular file or directory and use
NTFS_IOC_STREAM_READ and NTFS_IOC_STREAM_WRITE with a
struct ntfs_stream request. The request contains the stream name,
byte offset, and transfer length. Write requests create the stream when it
does not exist. Writes are not atomic. Error can leave partial data
changes, an extended stream size, or a newly created stream. bytes_returned
is valid only on success. Failed write does not report a completed byte
count. Use NTFS_IOC_STREAM_REMOVE to remove a stream and NTFS_IOC_LIST_STREAMS
to enumerate streams. Stream names are encoded with
the mounted NLS by default. Set NTFS_STREAM_FL_UTF16 to pass or receive
raw UTF-16LE names. These ioctls transfer stream data directly and do not
return a separate stream file descriptor.
|
