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 specified 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].