cifs: create a new Documentation/ directory and move docfiles into it

Currently, we have a number of documentation files that live under
fs/cifs/. Generally, these don't get picked up by distro packagers,
since they're in a non-standard location. Move them to a new spot
under Documentation/ instead.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 753 insertions, 0 deletions

diff --git a/Documentation/filesystems/cifs/README b/Documentation/filesystems/cifs/README
new file mode 100644
index 000000000000..2d5622f60e11
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+The CIFS VFS support for Linux supports many advanced network filesystem 
+features such as hierarchical dfs like namespace, hardlinks, locking and more.  
+It was designed to comply with the SNIA CIFS Technical Reference (which 
+supersedes the 1992 X/Open SMB Standard) as well as to perform best practice 
+practical interoperability with Windows 2000, Windows XP, Samba and equivalent 
+servers.  This code was developed in participation with the Protocol Freedom
+Information Foundation.
+
+Please see
+  http://protocolfreedom.org/ and
+  http://samba.org/samba/PFIF/
+for more details.
+
+
+For questions or bug reports please contact:
+    sfrench@samba.org (sfrench@us.ibm.com) 
+
+Build instructions:
+==================
+For Linux 2.4:
+1) Get the kernel source (e.g.from http://www.kernel.org)
+and download the cifs vfs source (see the project page
+at http://us1.samba.org/samba/Linux_CIFS_client.html)
+and change directory into the top of the kernel directory
+then patch the kernel (e.g. "patch -p1 < cifs_24.patch") 
+to add the cifs vfs to your kernel configure options if
+it has not already been added (e.g. current SuSE and UL
+users do not need to apply the cifs_24.patch since the cifs vfs is
+already in the kernel configure menu) and then
+mkdir linux/fs/cifs and then copy the current cifs vfs files from
+the cifs download to your kernel build directory e.g.
+
+	cp <cifs_download_dir>/fs/cifs/* to <kernel_download_dir>/fs/cifs
+	
+2) make menuconfig (or make xconfig)
+3) select cifs from within the network filesystem choices
+4) save and exit
+5) make dep
+6) make modules (or "make" if CIFS VFS not to be built as a module)
+
+For Linux 2.6:
+1) Download the kernel (e.g. from http://www.kernel.org)
+and change directory into the top of the kernel directory tree
+(e.g. /usr/src/linux-2.5.73)
+2) make menuconfig (or make xconfig)
+3) select cifs from within the network filesystem choices
+4) save and exit
+5) make
+
+
+Installation instructions:
+=========================
+If you have built the CIFS vfs as module (successfully) simply
+type "make modules_install" (or if you prefer, manually copy the file to
+the modules directory e.g. /lib/modules/2.4.10-4GB/kernel/fs/cifs/cifs.o).
+
+If you have built the CIFS vfs into the kernel itself, follow the instructions
+for your distribution on how to install a new kernel (usually you
+would simply type "make install").
+
+If you do not have the utility mount.cifs (in the Samba 3.0 source tree and on 
+the CIFS VFS web site) copy it to the same directory in which mount.smbfs and 
+similar files reside (usually /sbin).  Although the helper software is not  
+required, mount.cifs is recommended.  Eventually the Samba 3.0 utility program 
+"net" may also be helpful since it may someday provide easier mount syntax for
+users who are used to Windows e.g.
+	net use <mount point> <UNC name or cifs URL>
+Note that running the Winbind pam/nss module (logon service) on all of your
+Linux clients is useful in mapping Uids and Gids consistently across the
+domain to the proper network user.  The mount.cifs mount helper can be
+trivially built from Samba 3.0 or later source e.g. by executing:
+
+	gcc samba/source/client/mount.cifs.c -o mount.cifs
+
+If cifs is built as a module, then the size and number of network buffers
+and maximum number of simultaneous requests to one server can be configured.
+Changing these from their defaults is not recommended. By executing modinfo
+	modinfo kernel/fs/cifs/cifs.ko
+on kernel/fs/cifs/cifs.ko the list of configuration changes that can be made
+at module initialization time (by running insmod cifs.ko) can be seen.
+
+Allowing User Mounts
+====================
+To permit users to mount and unmount over directories they own is possible
+with the cifs vfs.  A way to enable such mounting is to mark the mount.cifs
+utility as suid (e.g. "chmod +s /sbin/mount.cifs). To enable users to 
+umount shares they mount requires
+1) mount.cifs version 1.4 or later
+2) an entry for the share in /etc/fstab indicating that a user may
+unmount it e.g.
+//server/usersharename  /mnt/username cifs user 0 0
+
+Note that when the mount.cifs utility is run suid (allowing user mounts), 
+in order to reduce risks, the "nosuid" mount flag is passed in on mount to
+disallow execution of an suid program mounted on the remote target.
+When mount is executed as root, nosuid is not passed in by default,
+and execution of suid programs on the remote target would be enabled
+by default. This can be changed, as with nfs and other filesystems, 
+by simply specifying "nosuid" among the mount options. For user mounts 
+though to be able to pass the suid flag to mount requires rebuilding 
+mount.cifs with the following flag: 
+ 
+        gcc samba/source/client/mount.cifs.c -DCIFS_ALLOW_USR_SUID -o mount.cifs
+
+There is a corresponding manual page for cifs mounting in the Samba 3.0 and
+later source tree in docs/manpages/mount.cifs.8 
+
+Allowing User Unmounts
+======================
+To permit users to ummount directories that they have user mounted (see above),
+the utility umount.cifs may be used.  It may be invoked directly, or if 
+umount.cifs is placed in /sbin, umount can invoke the cifs umount helper
+(at least for most versions of the umount utility) for umount of cifs
+mounts, unless umount is invoked with -i (which will avoid invoking a umount
+helper). As with mount.cifs, to enable user unmounts umount.cifs must be marked
+as suid (e.g. "chmod +s /sbin/umount.cifs") or equivalent (some distributions
+allow adding entries to a file to the /etc/permissions file to achieve the
+equivalent suid effect).  For this utility to succeed the target path
+must be a cifs mount, and the uid of the current user must match the uid
+of the user who mounted the resource.
+
+Also note that the customary way of allowing user mounts and unmounts is 
+(instead of using mount.cifs and unmount.cifs as suid) to add a line
+to the file /etc/fstab for each //server/share you wish to mount, but
+this can become unwieldy when potential mount targets include many
+or  unpredictable UNC names.
+
+Samba Considerations 
+==================== 
+To get the maximum benefit from the CIFS VFS, we recommend using a server that 
+supports the SNIA CIFS Unix Extensions standard (e.g.  Samba 2.2.5 or later or 
+Samba 3.0) but the CIFS vfs works fine with a wide variety of CIFS servers.  
+Note that uid, gid and file permissions will display default values if you do 
+not have a server that supports the Unix extensions for CIFS (such as Samba 
+2.2.5 or later).  To enable the Unix CIFS Extensions in the Samba server, add 
+the line: 
+
+	unix extensions = yes
+	
+to your smb.conf file on the server.  Note that the following smb.conf settings 
+are also useful (on the Samba server) when the majority of clients are Unix or 
+Linux: 
+
+	case sensitive = yes
+	delete readonly = yes 
+	ea support = yes
+
+Note that server ea support is required for supporting xattrs from the Linux
+cifs client, and that EA support is present in later versions of Samba (e.g. 
+3.0.6 and later (also EA support works in all versions of Windows, at least to
+shares on NTFS filesystems).  Extended Attribute (xattr) support is an optional
+feature of most Linux filesystems which may require enabling via
+make menuconfig. Client support for extended attributes (user xattr) can be
+disabled on a per-mount basis by specifying "nouser_xattr" on mount.
+
+The CIFS client can get and set POSIX ACLs (getfacl, setfacl) to Samba servers
+version 3.10 and later.  Setting POSIX ACLs requires enabling both XATTR and 
+then POSIX support in the CIFS configuration options when building the cifs
+module.  POSIX ACL support can be disabled on a per mount basic by specifying
+"noacl" on mount.
+ 
+Some administrators may want to change Samba's smb.conf "map archive" and 
+"create mask" parameters from the default.  Unless the create mask is changed
+newly created files can end up with an unnecessarily restrictive default mode,
+which may not be what you want, although if the CIFS Unix extensions are
+enabled on the server and client, subsequent setattr calls (e.g. chmod) can
+fix the mode.  Note that creating special devices (mknod) remotely 
+may require specifying a mkdev function to Samba if you are not using 
+Samba 3.0.6 or later.  For more information on these see the manual pages
+("man smb.conf") on the Samba server system.  Note that the cifs vfs,
+unlike the smbfs vfs, does not read the smb.conf on the client system 
+(the few optional settings are passed in on mount via -o parameters instead).  
+Note that Samba 2.2.7 or later includes a fix that allows the CIFS VFS to delete
+open files (required for strict POSIX compliance).  Windows Servers already 
+supported this feature. Samba server does not allow symlinks that refer to files
+outside of the share, so in Samba versions prior to 3.0.6, most symlinks to
+files with absolute paths (ie beginning with slash) such as:
+	 ln -s /mnt/foo bar
+would be forbidden. Samba 3.0.6 server or later includes the ability to create 
+such symlinks safely by converting unsafe symlinks (ie symlinks to server 
+files that are outside of the share) to a samba specific format on the server
+that is ignored by local server applications and non-cifs clients and that will
+not be traversed by the Samba server).  This is opaque to the Linux client
+application using the cifs vfs. Absolute symlinks will work to Samba 3.0.5 or
+later, but only for remote clients using the CIFS Unix extensions, and will
+be invisbile to Windows clients and typically will not affect local
+applications running on the same server as Samba.  
+
+Use instructions:
+================
+Once the CIFS VFS support is built into the kernel or installed as a module 
+(cifs.o), you can use mount syntax like the following to access Samba or Windows 
+servers: 
+
+  mount -t cifs //9.53.216.11/e$ /mnt -o user=myname,pass=mypassword
+
+Before -o the option -v may be specified to make the mount.cifs
+mount helper display the mount steps more verbosely.  
+After -o the following commonly used cifs vfs specific options
+are supported:
+
+  user=<username>
+  pass=<password>
+  domain=<domain name>
+  
+Other cifs mount options are described below.  Use of TCP names (in addition to
+ip addresses) is available if the mount helper (mount.cifs) is installed. If
+you do not trust the server to which are mounted, or if you do not have
+cifs signing enabled (and the physical network is insecure), consider use
+of the standard mount options "noexec" and "nosuid" to reduce the risk of 
+running an altered binary on your local system (downloaded from a hostile server
+or altered by a hostile router).
+
+Although mounting using format corresponding to the CIFS URL specification is
+not possible in mount.cifs yet, it is possible to use an alternate format
+for the server and sharename (which is somewhat similar to NFS style mount
+syntax) instead of the more widely used UNC format (i.e. \\server\share):
+  mount -t cifs tcp_name_of_server:share_name /mnt -o user=myname,pass=mypasswd
+
+When using the mount helper mount.cifs, passwords may be specified via alternate
+mechanisms, instead of specifying it after -o using the normal "pass=" syntax
+on the command line:
+1) By including it in a credential file. Specify credentials=filename as one
+of the mount options. Credential files contain two lines
+        username=someuser
+        password=your_password
+2) By specifying the password in the PASSWD environment variable (similarly
+the user name can be taken from the USER environment variable).
+3) By specifying the password in a file by name via PASSWD_FILE
+4) By specifying the password in a file by file descriptor via PASSWD_FD
+
+If no password is provided, mount.cifs will prompt for password entry
+
+Restrictions
+============
+Servers must support either "pure-TCP" (port 445 TCP/IP CIFS connections) or RFC 
+1001/1002 support for "Netbios-Over-TCP/IP." This is not likely to be a 
+problem as most servers support this.
+
+Valid filenames differ between Windows and Linux.  Windows typically restricts
+filenames which contain certain reserved characters (e.g.the character : 
+which is used to delimit the beginning of a stream name by Windows), while
+Linux allows a slightly wider set of valid characters in filenames. Windows
+servers can remap such characters when an explicit mapping is specified in
+the Server's registry.  Samba starting with version 3.10 will allow such 
+filenames (ie those which contain valid Linux characters, which normally
+would be forbidden for Windows/CIFS semantics) as long as the server is
+configured for Unix Extensions (and the client has not disabled
+/proc/fs/cifs/LinuxExtensionsEnabled).
+  
+
+CIFS VFS Mount Options
+======================
+A partial list of the supported mount options follows:
+  user		The user name to use when trying to establish
+		the CIFS session.
+  password	The user password.  If the mount helper is
+		installed, the user will be prompted for password
+		if not supplied.
+  ip		The ip address of the target server
+  unc		The target server Universal Network Name (export) to 
+		mount.	
+  domain	Set the SMB/CIFS workgroup name prepended to the
+		username during CIFS session establishment
+  forceuid	Set the default uid for inodes to the uid
+		passed in on mount. For mounts to servers
+		which do support the CIFS Unix extensions, such as a
+		properly configured Samba server, the server provides
+		the uid, gid and mode so this parameter should not be
+		specified unless the server and clients uid and gid
+		numbering differ.  If the server and client are in the
+		same domain (e.g. running winbind or nss_ldap) and
+		the server supports the Unix Extensions then the uid
+		and gid can be retrieved from the server (and uid
+		and gid would not have to be specifed on the mount. 
+		For servers which do not support the CIFS Unix
+		extensions, the default uid (and gid) returned on lookup
+		of existing files will be the uid (gid) of the person
+		who executed the mount (root, except when mount.cifs
+		is configured setuid for user mounts) unless the "uid=" 
+		(gid) mount option is specified. Also note that permission
+		checks (authorization checks) on accesses to a file occur
+		at the server, but there are cases in which an administrator
+		may want to restrict at the client as well.  For those
+		servers which do not report a uid/gid owner
+		(such as Windows), permissions can also be checked at the
+		client, and a crude form of client side permission checking 
+		can be enabled by specifying file_mode and dir_mode on 
+		the client.  (default)
+  forcegid	(similar to above but for the groupid instead of uid) (default)
+  noforceuid	Fill in file owner information (uid) by requesting it from
+		the server if possible. With this option, the value given in
+		the uid= option (on mount) will only be used if the server
+		can not support returning uids on inodes.
+  noforcegid	(similar to above but for the group owner, gid, instead of uid)
+  uid		Set the default uid for inodes, and indicate to the
+		cifs kernel driver which local user mounted. If the server
+		supports the unix extensions the default uid is
+		not used to fill in the owner fields of inodes (files)
+		unless the "forceuid" parameter is specified.
+  gid		Set the default gid for inodes (similar to above).
+  file_mode     If CIFS Unix extensions are not supported by the server
+		this overrides the default mode for file inodes.
+  fsc		Enable local disk caching using FS-Cache (off by default). This
+  		option could be useful to improve performance on a slow link,
+		heavily loaded server and/or network where reading from the
+		disk is faster than reading from the server (over the network).
+		This could also impact scalability positively as the
+		number of calls to the server are reduced. However, local
+		caching is not suitable for all workloads for e.g. read-once
+		type workloads. So, you need to consider carefully your
+		workload/scenario before using this option. Currently, local
+		disk caching is functional for CIFS files opened as read-only.
+  dir_mode      If CIFS Unix extensions are not supported by the server 
+		this overrides the default mode for directory inodes.
+  port		attempt to contact the server on this tcp port, before
+		trying the usual ports (port 445, then 139).
+  iocharset     Codepage used to convert local path names to and from
+		Unicode. Unicode is used by default for network path
+		names if the server supports it.  If iocharset is
+		not specified then the nls_default specified
+		during the local client kernel build will be used.
+		If server does not support Unicode, this parameter is
+		unused.
+  rsize		default read size (usually 16K). The client currently
+		can not use rsize larger than CIFSMaxBufSize. CIFSMaxBufSize
+		defaults to 16K and may be changed (from 8K to the maximum
+		kmalloc size allowed by your kernel) at module install time
+		for cifs.ko. Setting CIFSMaxBufSize to a very large value
+		will cause cifs to use more memory and may reduce performance
+		in some cases.  To use rsize greater than 127K (the original
+		cifs protocol maximum) also requires that the server support
+		a new Unix Capability flag (for very large read) which some
+		newer servers (e.g. Samba 3.0.26 or later) do. rsize can be
+		set from a minimum of 2048 to a maximum of 130048 (127K or
+		CIFSMaxBufSize, whichever is smaller)
+  wsize		default write size (default 57344)
+		maximum wsize currently allowed by CIFS is 57344 (fourteen
+		4096 byte pages)
+  actimeo=n	attribute cache timeout in seconds (default 1 second).
+		After this timeout, the cifs client requests fresh attribute
+		information from the server. This option allows to tune the
+		attribute cache timeout to suit the workload needs. Shorter
+		timeouts mean better the cache coherency, but increased number
+		of calls to the server. Longer timeouts mean reduced number
+		of calls to the server at the expense of less stricter cache
+		coherency checks (i.e. incorrect attribute cache for a short
+		period of time).
+  rw		mount the network share read-write (note that the
+		server may still consider the share read-only)
+  ro		mount network share read-only
+  version	used to distinguish different versions of the
+		mount helper utility (not typically needed)
+  sep		if first mount option (after the -o), overrides
+		the comma as the separator between the mount
+		parms. e.g.
+			-o user=myname,password=mypassword,domain=mydom
+		could be passed instead with period as the separator by
+			-o sep=.user=myname.password=mypassword.domain=mydom
+		this might be useful when comma is contained within username
+		or password or domain. This option is less important
+		when the cifs mount helper cifs.mount (version 1.1 or later)
+		is used.
+  nosuid        Do not allow remote executables with the suid bit 
+		program to be executed.  This is only meaningful for mounts
+		to servers such as Samba which support the CIFS Unix Extensions.
+		If you do not trust the servers in your network (your mount
+		targets) it is recommended that you specify this option for
+		greater security.
+  exec		Permit execution of binaries on the mount.
+  noexec	Do not permit execution of binaries on the mount.
+  dev		Recognize block devices on the remote mount.
+  nodev		Do not recognize devices on the remote mount.
+  suid          Allow remote files on this mountpoint with suid enabled to 
+		be executed (default for mounts when executed as root,
+		nosuid is default for user mounts).
+  credentials   Although ignored by the cifs kernel component, it is used by 
+		the mount helper, mount.cifs. When mount.cifs is installed it
+		opens and reads the credential file specified in order  
+		to obtain the userid and password arguments which are passed to
+		the cifs vfs.
+  guest         Although ignored by the kernel component, the mount.cifs
+		mount helper will not prompt the user for a password
+		if guest is specified on the mount options.  If no
+		password is specified a null password will be used.
+  perm          Client does permission checks (vfs_permission check of uid
+		and gid of the file against the mode and desired operation),
+		Note that this is in addition to the normal ACL check on the
+		target machine done by the server software. 
+		Client permission checking is enabled by default.
+  noperm        Client does not do permission checks.  This can expose
+		files on this mount to access by other users on the local
+		client system. It is typically only needed when the server
+		supports the CIFS Unix Extensions but the UIDs/GIDs on the
+		client and server system do not match closely enough to allow
+		access by the user doing the mount, but it may be useful with
+		non CIFS Unix Extension mounts for cases in which the default
+		mode is specified on the mount but is not to be enforced on the
+		client (e.g. perhaps when MultiUserMount is enabled)
+		Note that this does not affect the normal ACL check on the
+		target machine done by the server software (of the server
+		ACL against the user name provided at mount time).
+  serverino	Use server's inode numbers instead of generating automatically
+		incrementing inode numbers on the client.  Although this will
+		make it easier to spot hardlinked files (as they will have
+		the same inode numbers) and inode numbers may be persistent,
+		note that the server does not guarantee that the inode numbers
+		are unique if multiple server side mounts are exported under a
+		single share (since inode numbers on the servers might not
+		be unique if multiple filesystems are mounted under the same
+		shared higher level directory).  Note that some older
+		(e.g. pre-Windows 2000) do not support returning UniqueIDs
+		or the CIFS Unix Extensions equivalent and for those
+		this mount option will have no effect.  Exporting cifs mounts
+		under nfsd requires this mount option on the cifs mount.
+		This is now the default if server supports the 
+		required network operation.
+  noserverino   Client generates inode numbers (rather than using the actual one
+		from the server). These inode numbers will vary after
+		unmount or reboot which can confuse some applications,
+		but not all server filesystems support unique inode
+		numbers.
+  setuids       If the CIFS Unix extensions are negotiated with the server
+		the client will attempt to set the effective uid and gid of
+		the local process on newly created files, directories, and
+		devices (create, mkdir, mknod).  If the CIFS Unix Extensions
+		are not negotiated, for newly created files and directories
+		instead of using the default uid and gid specified on
+		the mount, cache the new file's uid and gid locally which means
+		that the uid for the file can change when the inode is
+	        reloaded (or the user remounts the share).
+  nosetuids     The client will not attempt to set the uid and gid on
+		on newly created files, directories, and devices (create, 
+		mkdir, mknod) which will result in the server setting the
+		uid and gid to the default (usually the server uid of the
+		user who mounted the share).  Letting the server (rather than
+		the client) set the uid and gid is the default. If the CIFS
+		Unix Extensions are not negotiated then the uid and gid for
+		new files will appear to be the uid (gid) of the mounter or the
+		uid (gid) parameter specified on the mount.
+  netbiosname   When mounting to servers via port 139, specifies the RFC1001
+		source name to use to represent the client netbios machine 
+		name when doing the RFC1001 netbios session initialize.
+  direct        Do not do inode data caching on files opened on this mount.
+		This precludes mmapping files on this mount. In some cases
+		with fast networks and little or no caching benefits on the
+		client (e.g. when the application is doing large sequential
+		reads bigger than page size without rereading the same data) 
+		this can provide better performance than the default
+		behavior which caches reads (readahead) and writes 
+		(writebehind) through the local Linux client pagecache 
+		if oplock (caching token) is granted and held. Note that
+		direct allows write operations larger than page size
+		to be sent to the server.
+  strictcache   Use for switching on strict cache mode. In this mode the
+		client read from the cache all the time it has Oplock Level II,
+		otherwise - read from the server. All written data are stored
+		in the cache, but if the client doesn't have Exclusive Oplock,
+		it writes the data to the server.
+  rwpidforward  Forward pid of a process who opened a file to any read or write
+		operation on that file. This prevent applications like WINE
+		from failing on read and write if we use mandatory brlock style.
+  acl   	Allow setfacl and getfacl to manage posix ACLs if server
+		supports them.  (default)
+  noacl 	Do not allow setfacl and getfacl calls on this mount
+  user_xattr    Allow getting and setting user xattrs (those attributes whose
+		name begins with "user." or "os2.") as OS/2 EAs (extended
+		attributes) to the server.  This allows support of the
+		setfattr and getfattr utilities. (default)
+  nouser_xattr  Do not allow getfattr/setfattr to get/set/list xattrs 
+  mapchars      Translate six of the seven reserved characters (not backslash)
+			*?<>|:
+		to the remap range (above 0xF000), which also
+		allows the CIFS client to recognize files created with
+		such characters by Windows's POSIX emulation. This can
+		also be useful when mounting to most versions of Samba
+		(which also forbids creating and opening files
+		whose names contain any of these seven characters).
+		This has no effect if the server does not support
+		Unicode on the wire.
+ nomapchars     Do not translate any of these seven characters (default).
+ nocase         Request case insensitive path name matching (case
+		sensitive is the default if the server supports it).
+		(mount option "ignorecase" is identical to "nocase")
+ posixpaths     If CIFS Unix extensions are supported, attempt to
+		negotiate posix path name support which allows certain
+		characters forbidden in typical CIFS filenames, without
+		requiring remapping. (default)
+ noposixpaths   If CIFS Unix extensions are supported, do not request
+		posix path name support (this may cause servers to
+		reject creatingfile with certain reserved characters).
+ nounix         Disable the CIFS Unix Extensions for this mount (tree
+		connection). This is rarely needed, but it may be useful
+		in order to turn off multiple settings all at once (ie
+		posix acls, posix locks, posix paths, symlink support
+		and retrieving uids/gids/mode from the server) or to
+		work around a bug in server which implement the Unix
+		Extensions.
+ nobrl          Do not send byte range lock requests to the server.
+		This is necessary for certain applications that break
+		with cifs style mandatory byte range locks (and most
+		cifs servers do not yet support requesting advisory
+		byte range locks).
+ forcemandatorylock Even if the server supports posix (advisory) byte range
+		locking, send only mandatory lock requests.  For some
+		(presumably rare) applications, originally coded for
+		DOS/Windows, which require Windows style mandatory byte range
+		locking, they may be able to take advantage of this option,
+		forcing the cifs client to only send mandatory locks
+		even if the cifs server would support posix advisory locks.
+		"forcemand" is accepted as a shorter form of this mount
+		option.
+ nostrictsync   If this mount option is set, when an application does an
+		fsync call then the cifs client does not send an SMB Flush
+		to the server (to force the server to write all dirty data
+		for this file immediately to disk), although cifs still sends
+		all dirty (cached) file data to the server and waits for the
+		server to respond to the write.  Since SMB Flush can be
+		very slow, and some servers may be reliable enough (to risk
+		delaying slightly flushing the data to disk on the server),
+		turning on this option may be useful to improve performance for
+		applications that fsync too much, at a small risk of server
+		crash.  If this mount option is not set, by default cifs will
+		send an SMB flush request (and wait for a response) on every
+		fsync call.
+ nodfs          Disable DFS (global name space support) even if the
+		server claims to support it.  This can help work around
+		a problem with parsing of DFS paths with Samba server
+		versions 3.0.24 and 3.0.25.
+ remount        remount the share (often used to change from ro to rw mounts
+	        or vice versa)
+ cifsacl        Report mode bits (e.g. on stat) based on the Windows ACL for
+	        the file. (EXPERIMENTAL)
+ servern        Specify the server 's netbios name (RFC1001 name) to use
+		when attempting to setup a session to the server. 
+		This is needed for mounting to some older servers (such
+		as OS/2 or Windows 98 and Windows ME) since they do not
+		support a default server name.  A server name can be up
+		to 15 characters long and is usually uppercased.
+ sfu            When the CIFS Unix Extensions are not negotiated, attempt to
+		create device files and fifos in a format compatible with
+		Services for Unix (SFU).  In addition retrieve bits 10-12
+		of the mode via the SETFILEBITS extended attribute (as
+		SFU does).  In the future the bottom 9 bits of the
+		mode also will be emulated using queries of the security
+		descriptor (ACL).
+ mfsymlinks     Enable support for Minshall+French symlinks
+		(see http://wiki.samba.org/index.php/UNIX_Extensions#Minshall.2BFrench_symlinks)
+		This option is ignored when specified together with the
+		'sfu' option. Minshall+French symlinks are used even if
+		the server supports the CIFS Unix Extensions.
+ sign           Must use packet signing (helps avoid unwanted data modification
+		by intermediate systems in the route).  Note that signing
+		does not work with lanman or plaintext authentication.
+ seal           Must seal (encrypt) all data on this mounted share before
+		sending on the network.  Requires support for Unix Extensions.
+		Note that this differs from the sign mount option in that it
+		causes encryption of data sent over this mounted share but other
+		shares mounted to the same server are unaffected.
+ locallease     This option is rarely needed. Fcntl F_SETLEASE is
+		used by some applications such as Samba and NFSv4 server to
+		check to see whether a file is cacheable.  CIFS has no way
+		to explicitly request a lease, but can check whether a file
+		is cacheable (oplocked).  Unfortunately, even if a file
+		is not oplocked, it could still be cacheable (ie cifs client
+		could grant fcntl leases if no other local processes are using
+		the file) for cases for example such as when the server does not
+		support oplocks and the user is sure that the only updates to
+		the file will be from this client. Specifying this mount option
+		will allow the cifs client to check for leases (only) locally
+		for files which are not oplocked instead of denying leases
+		in that case. (EXPERIMENTAL)
+ sec            Security mode.  Allowed values are:
+			none	attempt to connection as a null user (no name)
+			krb5    Use Kerberos version 5 authentication
+			krb5i   Use Kerberos authentication and packet signing
+			ntlm    Use NTLM password hashing (default)
+			ntlmi   Use NTLM password hashing with signing (if
+				/proc/fs/cifs/PacketSigningEnabled on or if
+				server requires signing also can be the default) 
+			ntlmv2  Use NTLMv2 password hashing      
+			ntlmv2i Use NTLMv2 password hashing with packet signing
+			lanman  (if configured in kernel config) use older
+				lanman hash
+hard		Retry file operations if server is not responding
+soft		Limit retries to unresponsive servers (usually only
+		one retry) before returning an error.  (default)
+
+The mount.cifs mount helper also accepts a few mount options before -o
+including:
+
+	-S      take password from stdin (equivalent to setting the environment
+		variable "PASSWD_FD=0"
+	-V      print mount.cifs version
+	-?      display simple usage information
+
+With most 2.6 kernel versions of modutils, the version of the cifs kernel
+module can be displayed via modinfo.
+
+Misc /proc/fs/cifs Flags and Debug Info
+=======================================
+Informational pseudo-files:
+DebugData		Displays information about active CIFS sessions and
+			shares, features enabled as well as the cifs.ko
+			version.
+Stats			Lists summary resource usage information as well as per
+			share statistics, if CONFIG_CIFS_STATS in enabled
+			in the kernel configuration.
+
+Configuration pseudo-files:
+PacketSigningEnabled	If set to one, cifs packet signing is enabled
+			and will be used if the server requires 
+			it.  If set to two, cifs packet signing is
+			required even if the server considers packet
+			signing optional. (default 1)
+SecurityFlags		Flags which control security negotiation and
+			also packet signing. Authentication (may/must)
+			flags (e.g. for NTLM and/or NTLMv2) may be combined with
+			the signing flags.  Specifying two different password
+			hashing mechanisms (as "must use") on the other hand 
+			does not make much sense. Default flags are 
+				0x07007 
+			(NTLM, NTLMv2 and packet signing allowed).  The maximum 
+			allowable flags if you want to allow mounts to servers
+			using weaker password hashes is 0x37037 (lanman,
+			plaintext, ntlm, ntlmv2, signing allowed).  Some
+			SecurityFlags require the corresponding menuconfig
+			options to be enabled (lanman and plaintext require
+			CONFIG_CIFS_WEAK_PW_HASH for example).  Enabling
+			plaintext authentication currently requires also
+			enabling lanman authentication in the security flags
+			because the cifs module only supports sending
+			laintext passwords using the older lanman dialect
+			form of the session setup SMB.  (e.g. for authentication
+			using plain text passwords, set the SecurityFlags
+			to 0x30030):
+ 
+			may use packet signing 				0x00001
+			must use packet signing				0x01001
+			may use NTLM (most common password hash)	0x00002
+			must use NTLM					0x02002
+			may use NTLMv2					0x00004
+			must use NTLMv2					0x04004
+			may use Kerberos security			0x00008
+			must use Kerberos				0x08008
+			may use lanman (weak) password hash  		0x00010
+			must use lanman password hash			0x10010
+			may use plaintext passwords    			0x00020
+			must use plaintext passwords			0x20020
+			(reserved for future packet encryption)		0x00040
+
+cifsFYI			If set to non-zero value, additional debug information
+			will be logged to the system error log.  This field
+			contains three flags controlling different classes of
+			debugging entries.  The maximum value it can be set
+			to is 7 which enables all debugging points (default 0).
+			Some debugging statements are not compiled into the
+			cifs kernel unless CONFIG_CIFS_DEBUG2 is enabled in the
+			kernel configuration. cifsFYI may be set to one or
+			nore of the following flags (7 sets them all):
+
+			log cifs informational messages			0x01
+			log return codes from cifs entry points		0x02
+			log slow responses (ie which take longer than 1 second)
+			  CONFIG_CIFS_STATS2 must be enabled in .config	0x04
+				
+				
+traceSMB		If set to one, debug information is logged to the
+			system error log with the start of smb requests
+			and responses (default 0)
+LookupCacheEnable	If set to one, inode information is kept cached
+			for one second improving performance of lookups
+			(default 1)
+OplockEnabled		If set to one, safe distributed caching enabled.
+			(default 1)
+LinuxExtensionsEnabled	If set to one then the client will attempt to
+			use the CIFS "UNIX" extensions which are optional
+			protocol enhancements that allow CIFS servers
+			to return accurate UID/GID information as well
+			as support symbolic links. If you use servers
+			such as Samba that support the CIFS Unix
+			extensions but do not want to use symbolic link
+			support and want to map the uid and gid fields 
+			to values supplied at mount (rather than the 
+			actual values, then set this to zero. (default 1)
+
+These experimental features and tracing can be enabled by changing flags in 
+/proc/fs/cifs (after the cifs module has been installed or built into the 
+kernel, e.g.  insmod cifs).  To enable a feature set it to 1 e.g.  to enable 
+tracing to the kernel message log type: 
+
+	echo 7 > /proc/fs/cifs/cifsFYI
+	
+cifsFYI functions as a bit mask. Setting it to 1 enables additional kernel
+logging of various informational messages.  2 enables logging of non-zero
+SMB return codes while 4 enables logging of requests that take longer
+than one second to complete (except for byte range lock requests). 
+Setting it to 4 requires defining CONFIG_CIFS_STATS2 manually in the
+source code (typically by setting it in the beginning of cifsglob.h),
+and setting it to seven enables all three.  Finally, tracing
+the start of smb requests and responses can be enabled via:
+
+	echo 1 > /proc/fs/cifs/traceSMB
+
+Per share (per client mount) statistics are available in /proc/fs/cifs/Stats
+if the kernel was configured with cifs statistics enabled.  The statistics
+represent the number of successful (ie non-zero return code from the server) 
+SMB responses to some of the more common commands (open, delete, mkdir etc.).
+Also recorded is the total bytes read and bytes written to the server for
+that share.  Note that due to client caching effects this can be less than the
+number of bytes read and written by the application running on the client.
+The statistics for the number of total SMBs and oplock breaks are different in
+that they represent all for that share, not just those for which the server
+returned success.
+	
+Also note that "cat /proc/fs/cifs/DebugData" will display information about
+the active sessions and the shares that are mounted.
+
+Enabling Kerberos (extended security) works but requires version 1.2 or later
+of the helper program cifs.upcall to be present and to be configured in the
+/etc/request-key.conf file.  The cifs.upcall helper program is from the Samba
+project(http://www.samba.org). NTLM and NTLMv2 and LANMAN support do not
+require this helper. Note that NTLMv2 security (which does not require the
+cifs.upcall helper program), instead of using Kerberos, is sufficient for
+some use cases.
+
+DFS support allows transparent redirection to shares in an MS-DFS name space.
+In addition, DFS support for target shares which are specified as UNC
+names which begin with host names (rather than IP addresses) requires
+a user space helper (such as cifs.upcall) to be present in order to
+translate host names to ip address, and the user space helper must also
+be configured in the file /etc/request-key.conf.  Samba, Windows servers and
+many NAS appliances support DFS as a way of constructing a global name
+space to ease network configuration and improve reliability.
+
+To use cifs Kerberos and DFS support, the Linux keyutils package should be
+installed and something like the following lines should be added to the
+/etc/request-key.conf file:
+
+create cifs.spnego * * /usr/local/sbin/cifs.upcall %k
+create dns_resolver * * /usr/local/sbin/cifs.upcall %k
+
+CIFS kernel module parameters
+=============================
+These module parameters can be specified or modified either during the time of
+module loading or during the runtime by using the interface
+	/proc/module/cifs/parameters/<param>
+
+i.e. echo "value" > /sys/module/cifs/parameters/<param>
+
+1. enable_oplocks - Enable or disable oplocks. Oplocks are enabled by default.
+		    [Y/y/1]. To disable use any of [N/n/0].
+