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>

fs/ntfs/ChangeLog

@@ -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.
 

fs/ntfs/Makefile

@@ -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