cifs: Add a tracepoint to log EIO errors

cifs: Add a tracepoint to log EIO errors

Add a tracepoint to log EIO errors and give it the capacity to convey up to
two integers of information.  This is then wrapped with three functions:

 int smb_EIO(enum smb_eio_trace trace)
 int smb_EIO1(enum smb_eio_trace trace, unsigned long info)
 int smb_EIO2(enum smb_eio_trace trace, unsigned long info,
	      unsigned long info2)

depending on how many bits of info are desired to be logged with any
particular trace.  The functions all return -EIO and can be used in place
of -EIO.

The trace argument is an enum value that gets translated to a string when
the trace is printed.

This makes is easier to log EIO instances when the client is under high
load than turning on a printk wrapper such as cifs_dbg().  Granted, EIO
could have its own separate EIO printing since EIO shouldn't happen.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>