cifs: Ratelimit kernel log messages

cifs: Ratelimit kernel log messages

commit ec7147a99e33a9e4abad6fc6e1b40d15df045d53 upstream.

Under some conditions, CIFS can repeatedly call the cifs_dbg() logging
wrapper. If done rapidly enough, the console framebuffer can softlockup
or "rcu_sched self-detected stall". Apply the built-in log ratelimiters
to prevent such hangs.

Signed-off-by: Jamie Bainbridge <jamie.bainbridge@gmail.com>
Signed-off-by: Steve French <smfrench@gmail.com>
[bwh: Backported to 3.2:
 - cifs_dbg() and cifs_vfs_err() do not exist, but make similar changes
   to cifsfyi(), cifswarn() and cifserror()]
 - Include <linux/ratelimit.h> explicitly]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>