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-rw-r--r--Documentation/filesystems/ntfs.txt42
1 files changed, 38 insertions, 4 deletions
diff --git a/Documentation/filesystems/ntfs.txt b/Documentation/filesystems/ntfs.txt
index a5fbc8e897fa..614de3124901 100644
--- a/Documentation/filesystems/ntfs.txt
+++ b/Documentation/filesystems/ntfs.txt
@@ -50,9 +50,14 @@ userspace utilities, etc.
Features
========
-- This is a complete rewrite of the NTFS driver that used to be in the kernel.
- This new driver implements NTFS read support and is functionally equivalent
- to the old ntfs driver.
+- This is a complete rewrite of the NTFS driver that used to be in the 2.4 and
+ earlier kernels. This new driver implements NTFS read support and is
+ functionally equivalent to the old ntfs driver and it also implements limited
+ write support. The biggest limitation at present is that files/directories
+ cannot be created or deleted. See below for the list of write features that
+ are so far supported. Another limitation is that writing to compressed files
+ is not implemented at all. Also, neither read nor write access to encrypted
+ files is so far implemented.
- The new driver has full support for sparse files on NTFS 3.x volumes which
the old driver isn't happy with.
- The new driver supports execution of binaries due to mmap() now being
@@ -78,7 +83,20 @@ Features
- The new driver supports fsync(2), fdatasync(2), and msync(2).
- The new driver supports readv(2) and writev(2).
- The new driver supports access time updates (including mtime and ctime).
-
+- The new driver supports truncate(2) and open(2) with O_TRUNC. But at present
+ only very limited support for highly fragmented files, i.e. ones which have
+ their data attribute split across multiple extents, is included. Another
+ limitation is that at present truncate(2) will never create sparse files,
+ since to mark a file sparse we need to modify the directory entry for the
+ file and we do not implement directory modifications yet.
+- The new driver supports write(2) which can both overwrite existing data and
+ extend the file size so that you can write beyond the existing data. Also,
+ writing into sparse regions is supported and the holes are filled in with
+ clusters. But at present only limited support for highly fragmented files,
+ i.e. ones which have their data attribute split across multiple extents, is
+ included. Another limitation is that write(2) will never create sparse
+ files, since to mark a file sparse we need to modify the directory entry for
+ the file and we do not implement directory modifications yet.
Supported mount options
=======================
@@ -439,6 +457,22 @@ ChangeLog
Note, a technical ChangeLog aimed at kernel hackers is in fs/ntfs/ChangeLog.
+2.1.25:
+ - Write support is now extended with write(2) being able to both
+ overwrite existing file data and to extend files. Also, if a write
+ to a sparse region occurs, write(2) will fill in the hole. Note,
+ mmap(2) based writes still do not support writing into holes or
+ writing beyond the initialized size.
+ - Write support has a new feature and that is that truncate(2) and
+ open(2) with O_TRUNC are now implemented thus files can be both made
+ smaller and larger.
+ - Note: Both write(2) and truncate(2)/open(2) with O_TRUNC still have
+ limitations in that they
+ - only provide limited support for highly fragmented files.
+ - only work on regular, i.e. uncompressed and unencrypted files.
+ - never create sparse files although this will change once directory
+ operations are implemented.
+ - Lots of bug fixes and enhancements across the board.
2.1.24:
- Support journals ($LogFile) which have been modified by chkdsk. This
means users can boot into Windows after we marked the volume dirty.