[mirror_ubuntu-zesty-kernel.git] / Documentation / filesystems / cifs / TODO

Version 2.03 August 1, 2014

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) SMB3 (and SMB3.02) missing optional features:
   - RDMA
   - multichannel (started)
   - directory leases (improved metadata caching)
   - T10 copy offload (copy chunk is only mechanism supported)
   - encrypted shares

b) improved sparse file support

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

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

e) improve support for very old servers (OS/2 and Win9x for example)
Including support for changing the time remotely (utimes command).

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

g) 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).

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

i) Finish inotify 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.   

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

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

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

m) 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.

n) DOS attrs - returned as pseudo-xattr in Samba format (check VFAT and NTFS for this too)

o) mount check for unmatched uids

p) Add support for new vfs entry point for fallocate

q) Add tools to take advantage of cifs/smb3 specific ioctls and features
such as "CopyChunk" (fast server side file copy)

r) encrypted file support

s) improved stats gathering, tools (perhaps integration with nfsometer?)

t) allow setting more NTFS/SMB3 file attributes remotely (currently limited to compressed
file attribute via chflags)

u) mount helper GUI (to simplify the various configuration options on mount)


KNOWN BUGS
====================================
See http://bugzilla.samba.org - search on product "CifsVFS" for
current bug list.  Also check http://bugzilla.kernel.org (Product = File System, Component = CIFS)

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

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) Improve xfstest's cifs enablement and adapt xfstests where needed to test
cifs better

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
Commit	Line	Data
2075cf0b	1	Version 2.03 August 1, 2014
1da177e4 LT	2
	3	A Partial List of Missing Features
	4	==================================
	5
	6	Contributions are welcome. There are plenty of opportunities
	7	for visible, important contributions to this module. Here
	8	is a partial list of the known problems and missing features:
	9
2075cf0b SF	10	a) SMB3 (and SMB3.02) missing optional features:
	11	- RDMA
	12	- multichannel (started)
	13	- directory leases (improved metadata caching)
	14	- T10 copy offload (copy chunk is only mechanism supported)
	15	- encrypted shares
1da177e4	16
2075cf0b	17	b) improved sparse file support
1da177e4	18
2075cf0b	19	c) Directory entry caching relies on a 1 second timer, rather than
1da177e4 LT	20	using FindNotify or equivalent. - (started)
1da177e4 LT	21
2075cf0b	22	d) quota support (needs minor kernel change since quota calls
9a899e76	23	to make it to network filesystems or deviceless filesystems)
1da177e4	24
2075cf0b	25	e) improve support for very old servers (OS/2 and Win9x for example)
0e4bbde9 SF	26	Including support for changing the time remotely (utimes command).
0e4bbde9 SF	27
2075cf0b	28	f) hook lower into the sockets api (as NFS/SunRPC does) to avoid the
1da177e4 LT	29	extra copy in/out of the socket buffers in some cases.
1da177e4 LT	30
2075cf0b	31	g) Better optimize open (and pathbased setfilesize) to reduce the
1da177e4 LT	32	oplock breaks coming from windows srv. Piggyback identical file
	33	opens on top of each other by incrementing reference count rather
	34	than resending (helps reduce server resource utilization and avoid
	35	spurious oplock breaks).
	36
2075cf0b	37	h) Add support for storing symlink info to Windows servers
1da177e4 LT	38	in the Extended Attribute format their SFU clients would recognize.
1da177e4 LT	39
2075cf0b	40	i) Finish inotify support so kde and gnome file list windows
9a899e76 SF	41	will autorefresh (partially complete by Asser). Needs minor kernel
9a899e76 SF	42	vfs change to support removing D_NOTIFY on a file.
1da177e4	43
2075cf0b	44	j) Add GUI tool to configure /proc/fs/cifs settings and for display of
1da177e4 LT	45	the CIFS statistics (started)
1da177e4 LT	46
2075cf0b	47	k) implement support for security and trusted categories of xattrs
1da177e4 LT	48	(requires minor protocol extension) to enable better support for SELINUX
1da177e4 LT	49
2075cf0b	50	l) Implement O_DIRECT flag on open (already supported on mount)
737b758c	51
2075cf0b	52	m) Create UID mapping facility so server UIDs can be mapped on a per
9ea1f8f5 SF	53	mount or a per server basis to client UIDs or nobody if no mapping
	54	exists. This is helpful when Unix extensions are negotiated to
	55	allow better permission checking when UIDs differ on the server
	56	and client. Add new protocol request to the CIFS protocol
	57	standard for asking the server for the corresponding name of a
	58	particular uid.
	59
2075cf0b SF	60	n) DOS attrs - returned as pseudo-xattr in Samba format (check VFAT and NTFS for this too)
	61
	62	o) mount check for unmatched uids
9a899e76	63
2075cf0b	64	p) Add support for new vfs entry point for fallocate
9a899e76	65
2075cf0b SF	66	q) Add tools to take advantage of cifs/smb3 specific ioctls and features
2075cf0b SF	67	such as "CopyChunk" (fast server side file copy)
deb0420c	68
2075cf0b	69	r) encrypted file support
deb0420c	70
2075cf0b	71	s) improved stats gathering, tools (perhaps integration with nfsometer?)
9a899e76	72
2075cf0b SF	73	t) allow setting more NTFS/SMB3 file attributes remotely (currently limited to compressed
2075cf0b SF	74	file attribute via chflags)
deb0420c	75
2075cf0b	76	u) mount helper GUI (to simplify the various configuration options on mount)
deb0420c	77
2075cf0b SF	78
2075cf0b SF	79	KNOWN BUGS
1da177e4	80	====================================
6a0b4824	81	See http://bugzilla.samba.org - search on product "CifsVFS" for
2075cf0b	82	current bug list. Also check http://bugzilla.kernel.org (Product = File System, Component = CIFS)
6a0b4824	83
1da177e4 LT	84	1) existing symbolic links (Windows reparse points) are recognized but
1da177e4 LT	85	can not be created remotely. They are implemented for Samba and those that
6a0b4824 SF	86	support the CIFS Unix extensions, although earlier versions of Samba
6a0b4824 SF	87	overly restrict the pathnames.
1da177e4 LT	88	2) follow_link and readdir code does not follow dfs junctions
1da177e4 LT	89	but recognizes them
1da177e4 LT	90
	91	Misc testing to do
	92	==================
	93	1) check out max path names and max path name components against various server
	94	types. Try nested symlinks (8 deep). Return max path name in stat -f information
	95
2075cf0b SF	96	2) Improve xfstest's cifs enablement and adapt xfstests where needed to test
2075cf0b SF	97	cifs better
1da177e4 LT	98
	99	3) Additional performance testing and optimization using iozone and similar -
	100	there are some easy changes that can be done to parallelize sequential writes,
	101	and when signing is disabled to request larger read sizes (larger than
	102	negotiated size) and send larger write sizes to modern servers.
	103
2075cf0b	104	4) More exhaustively test against less common servers