NTFS: The big ntfs write(2) rewrite has arrived. We now implement our own

file operations ->write(), ->aio_write(), and ->writev() for regular
      files.  This replaces the old use of generic_file_write(), et al and
      the address space operations ->prepare_write and ->commit_write.
      This means that both sparse and non-sparse (unencrypted and
      uncompressed) files can now be extended using the normal write(2)
      code path.  There are two limitations at present and these are that
      we never create sparse files and that we only have limited support
      for highly fragmented files, i.e. ones whose data attribute is split
      across multiple extents.   When such a case is encountered,
      EOPNOTSUPP is returned.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
This commit is contained in:
Anton Altaparmakov 2005-10-11 15:40:40 +01:00
parent 29f5f3c141
commit 98b270362b
4 changed files with 2280 additions and 49 deletions

View file

@ -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.

View file

@ -1,16 +1,15 @@
ToDo/Notes:
- Find and fix bugs.
- In between ntfs_prepare/commit_write, need exclusion between
simultaneous file extensions. This is given to us by holding i_sem
on the inode. The only places in the kernel when a file is resized
are prepare/commit write and ntfs_truncate() for both of which i_sem
is held. Just have to be careful in read-/writepage and other helpers
- The only places in the kernel where a file is resized are
ntfs_file_write*() and ntfs_truncate() for both of which i_sem is
held. Just have to be careful in read-/writepage and other helpers
not running under i_sem that we play nice... Also need to be careful
with initialized_size extention in ntfs_prepare_write and writepage.
UPDATE: The only things that need to be checked are
prepare/commit_write as well as the compressed write and the other
attribute resize/write cases like index attributes, etc. For now
none of these are implemented so are safe.
with initialized_size extension in ntfs_file_write*() and writepage.
UPDATE: The only things that need to be checked are the compressed
write and the other attribute resize/write cases like index
attributes, etc. For now none of these are implemented so are safe.
- Implement filling in of holes in aops.c::ntfs_writepage() and its
helpers.
- Implement mft.c::sync_mft_mirror_umount(). We currently will just
leave the volume dirty on umount if the final iput(vol->mft_ino)
causes a write of any mirrored mft records due to the mft mirror
@ -20,7 +19,7 @@ ToDo/Notes:
- Enable the code for setting the NT4 compatibility flag when we start
making NTFS 1.2 specific modifications.
2.1.25-WIP
2.1.25 - (Almost) fully implement write(2) and truncate(2).
- Change ntfs_map_runlist_nolock(), ntfs_attr_find_vcn_nolock() and
{__,}ntfs_cluster_free() to also take an optional attribute search
@ -49,7 +48,12 @@ ToDo/Notes:
extend the allocation of an attributes. Optionally, the data size,
but not the initialized size can be extended, too.
- Implement fs/ntfs/inode.[hc]::ntfs_truncate(). It only supports
uncompressed and unencrypted files.
uncompressed and unencrypted files and it never creates sparse files
at least for the moment (making a file sparse requires us to modify
its directory entries and we do not support directory operations at
the moment). Also, support for highly fragmented files, i.e. ones
whose data attribute is split across multiple extents, is severly
limited. When such a case is encountered, EOPNOTSUPP is returned.
- Enable ATTR_SIZE attribute changes in ntfs_setattr(). This completes
the initial implementation of file truncation. Now both open(2)ing
a file with the O_TRUNC flag and the {,f}truncate(2) system calls
@ -61,6 +65,16 @@ ToDo/Notes:
and cond_resched() in the main loop as we could be dirtying a lot of
pages and this ensures we play nice with the VM and the system as a
whole.
- Implement file operations ->write, ->aio_write, ->writev for regular
files. This replaces the old use of generic_file_write(), et al and
the address space operations ->prepare_write and ->commit_write.
This means that both sparse and non-sparse (unencrypted and
uncompressed) files can now be extended using the normal write(2)
code path. There are two limitations at present and these are that
we never create sparse files and that we only have limited support
for highly fragmented files, i.e. ones whose data attribute is split
across multiple extents. When such a case is encountered,
EOPNOTSUPP is returned.
2.1.24 - Lots of bug fixes and support more clean journal states.

View file

@ -6,7 +6,7 @@ ntfs-objs := aops.o attrib.o collate.o compress.o debug.o dir.o file.o \
index.o inode.o mft.o mst.o namei.o runlist.o super.o sysctl.o \
unistr.o upcase.o
EXTRA_CFLAGS = -DNTFS_VERSION=\"2.1.25-WIP\"
EXTRA_CFLAGS = -DNTFS_VERSION=\"2.1.25\"
ifeq ($(CONFIG_NTFS_DEBUG),y)
EXTRA_CFLAGS += -DDEBUG

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