WSL2-Linux-Kernel/fs/cifs/TODO

version 1.36 September 6, 2005

A Partial List of Missing Features
==================================

Contributions are welcome.  There are plenty of opportunities
for visible, important contributions to this module.  Here
is a partial list of the known problems and missing features:

a) Support for SecurityDescriptors(Windows/CIFS ACLs) for chmod/chgrp/chown
so that these operations can be supported to Windows servers

b) Mapping POSIX ACLs (and eventually NFSv4 ACLs) to CIFS
SecurityDescriptors

c) Better pam/winbind integration (e.g. to handle uid mapping
better)

d) Kerberos/SPNEGO session setup support - (started)

e) NTLMv2 authentication (mostly implemented)

f) MD5-HMAC signing SMB PDUs when SPNEGO style SessionSetup 
used (Kerberos or NTLMSSP). Signing alreadyimplemented for NTLM
and raw NTLMSSP already. This is important when enabling
extended security and mounting to Windows 2003 Servers

f) Directory entry caching relies on a 1 second timer, rather than 
using FindNotify or equivalent.  - (started)

g) A few byte range testcases fail due to POSIX vs. Windows/CIFS
style byte range lock differences.  Save byte range locks so
reconnect can replay them.  

h) Support unlock all (unlock 0,MAX_OFFSET)
by unlocking all known byte range locks that we locked on the file.

i) quota support (needs minor kernel change since quota calls
to make it to network filesystems or deviceless filesystems)

j) finish writepages support (multi-page write behind for improved
performance) and syncpage. Started by Shaggy.

k) hook lower into the sockets api (as NFS/SunRPC does) to avoid the
extra copy in/out of the socket buffers in some cases.

l) finish support for IPv6.  This is mostly complete but
needs a simple conversion of ipv6 to sin6_addr from the
address in string representation.

m) Better optimize open (and pathbased setfilesize) to reduce the
oplock breaks coming from windows srv.  Piggyback identical file
opens on top of each other by incrementing reference count rather
than resending (helps reduce server resource utilization and avoid
spurious oplock breaks).

o) Improve performance of readpages by sending more than one read
at a time when 8 pages or more are requested. In conjuntion
add support for async_cifs_readpages.

p) Add support for storing symlink and fifo info to Windows servers 
in the Extended Attribute format their SFU clients would recognize.

q) Finish fcntl D_NOTIFY support so kde and gnome file list windows
will autorefresh (partially complete by Asser). Needs minor kernel
vfs change to support removing D_NOTIFY on a file.   

r) Add GUI tool to configure /proc/fs/cifs settings and for display of
the CIFS statistics (started)

s) implement support for security and trusted categories of xattrs
(requires minor protocol extension) to enable better support for SELINUX

t) Implement O_DIRECT flag on open (already supported on mount)

u) Create UID mapping facility so server UIDs can be mapped on a per
mount or a per server basis to client UIDs or nobody if no mapping
exists.  This is helpful when Unix extensions are negotiated to
allow better permission checking when UIDs differ on the server
and client.  Add new protocol request to the CIFS protocol 
standard for asking the server for the corresponding name of a
particular uid.

v) Add support for CIFS Unix and also the newer POSIX extensions to the
server side for Samba 4.

w) Finish up the dos time conversion routines needed to return old server
time to the client (default time, of now or time 0 is used now for these 
very old servers)

x) Add support for OS/2 (LANMAN 1.2 and LANMAN2.1 based SMB servers)

y) Finish testing of Windows 9x/Windows ME server support (started).

KNOWN BUGS (updated April 29, 2005)
====================================
See http://bugzilla.samba.org - search on product "CifsVFS" for
current bug list.

1) existing symbolic links (Windows reparse points) are recognized but
can not be created remotely. They are implemented for Samba and those that
support the CIFS Unix extensions, although earlier versions of Samba
overly restrict the pathnames.
2) follow_link and readdir code does not follow dfs junctions
but recognizes them
3) create of new files to FAT partitions on Windows servers can
succeed but still return access denied (appears to be Windows 
server not cifs client problem) and has not been reproduced recently.
NTFS partitions do not have this problem.
4) debug connectathon lock test case 10 which fails against
Samba (may be unmappable due to POSIX to Windows lock model
differences but worth investigating).  Also debug Samba to 
see why lock test case 7 takes longer to complete to Samba
than to Windows.

Misc testing to do
==================
1) check out max path names and max path name components against various server
types. Try nested symlinks (8 deep). Return max path name in stat -f information

2) Modify file portion of ltp so it can run against a mounted network
share and run it against cifs vfs.

3) Additional performance testing and optimization using iozone and similar - 
there are some easy changes that can be done to parallelize sequential writes,
and when signing is disabled to request larger read sizes (larger than 
negotiated size) and send larger write sizes to modern servers.

4) More exhaustively test against less common servers.  More testing
against Windows 9x, Windows ME servers.