cifs: replace /proc/fs/cifs/Experimental with a module parm

This flag currently only affects whether we allow "zero-copy" writes
with signing enabled. Typically we map pages in the pagecache directly
into the write request. If signing is enabled however and the contents
of the page change after the signature is calculated but before the
write is sent then the signature will be wrong. Servers typically
respond to this by closing down the socket.

Still, this can provide a performance benefit so the "Experimental" flag
was overloaded to allow this. That's really not a good place for this
option however since it's not clear what that flag does.

Move that flag instead to a new module parameter that better describes
its purpose. That's also better since it can be set at module insertion
time by configuring modprobe.d.

Reviewed-by: Suresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 0 insertions, 16 deletions

diff --git a/fs/cifs/README b/fs/cifs/README
index fe1683590828..74ab165fc646 100644
--- a/fs/cifs/README
+++ b/fs/cifs/README
@@ -685,22 +685,6 @@ LinuxExtensionsEnabled	If set to one then the client will attempt to
                         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)
-Experimental            When set to 1 used to enable certain experimental
-                        features (currently enables multipage writes
-                        when signing is enabled, the multipage write
-                        performance enhancement was disabled when
-                        signing turned on in case buffer was modified
-                        just before it was sent, also this flag will
-                        be used to use the new experimental directory change 
-                        notification code).  When set to 2 enables
-                        an additional experimental feature, "raw ntlmssp"
-                        session establishment support (which allows
-                        specifying "sec=ntlmssp" on mount). The Linux cifs
-                        module will use ntlmv2 authentication encapsulated
-                        in "raw ntlmssp" (not using SPNEGO) when
-                        "sec=ntlmssp" is specified on mount.
-                        This support also requires building cifs with
-                        the CONFIG_CIFS_EXPERIMENTAL configuration flag.
 
 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