[PATCH] DAC960 patch to entry points with a new fix

From: Dave Olien <dmo@osdl.org>

Christoph submitted a patch to linus last week fixing up some DAC960 driver
entry points.  That patch will OOPS during boot on version 2 controller
types.  Christoph's version of the disk_size() function was dereferencing
a NULL pointer in it's "else" clause.

Christoph's patch hasn't appeared in linus's BK tree yet.  So, I'm
resending Christoph's orignal patch with my fix to disk_size() included.
This patch can be applied to the driver in Linus's BK tree from April 28.

Here's Christoph's original description of his patch:

Some grepping showed that DAC960's open routine was duplicating parts
of check_disk_change().  I went on fixing this by implementing a
media_changed method and making DAC960_Open use it.  While looking
at the surrounding code I noticed that

  (a) all methods weren't using the private data the upperlayer
      hands to it properly, but instead using kdev_t-based indexes
  (b) DAC960_Open/DAC960_Release was keeping never used counters
  (c) DAC960_Open was doing tons of checks the upperlayer already does
  (d) DAC960_Release was entirely superflous.

The patch below corrects that and rewrites the block entry points
into readable code - 100 LOC are gone and the same amount replaced
by readable code.

drivers/block/DAC960.h

@@ -2364,7 +2364,6 @@ typedef struct DAC960_Controller
   unsigned short MaxBlocksPerCommand;
   unsigned short ControllerScatterGatherLimit;
   unsigned short DriverScatterGatherLimit;
-  unsigned int ControllerUsageCount;
   u64		BounceBufferLimit;
   unsigned int CombinedStatusBufferLength;
   unsigned int InitialStatusLength;
@@ -2397,7 +2396,6 @@ typedef struct DAC960_Controller
   DAC960_Command_T InitialCommand;
   DAC960_Command_T *Commands[DAC960_MaxDriverQueueDepth];
   PROC_DirectoryEntry_T *ControllerProcEntry;
-  unsigned int LogicalDriveUsageCount[DAC960_MaxLogicalDrives];
   boolean LogicalDriveInitiallyAccessible[DAC960_MaxLogicalDrives];
   void (*QueueCommand)(DAC960_Command_T *Command);
   boolean (*ReadControllerConfiguration)(struct DAC960_Controller *);
@@ -4242,9 +4240,6 @@ static irqreturn_t DAC960_P_InterruptHandler(int, void *, Registers_T *);
 static void DAC960_V1_QueueMonitoringCommand(DAC960_Command_T *);
 static void DAC960_V2_QueueMonitoringCommand(DAC960_Command_T *);
 static void DAC960_MonitoringTimerFunction(unsigned long);
-static int DAC960_Open(Inode_T *, File_T *);
-static int DAC960_Release(Inode_T *, File_T *);
-static int DAC960_IOCTL(Inode_T *, File_T *, unsigned int, unsigned long);
 static int DAC960_UserIOCTL(Inode_T *, File_T *, unsigned int, unsigned long);
 static void DAC960_Message(DAC960_MessageLevel_T, unsigned char *,
 			   DAC960_Controller_T *, ...);