sg: relax 16 byte cdb restriction

 - remove the 16 byte CDB (SCSI command) length limit from the sg driver
   by handling longer CDBs the same way as the bsg driver. Remove comment
   from sg.h public interface about the cmd_len field being limited to 16
   bytes.
 - remove some dead code caused by this change
 - cleanup comment block at the top of sg.h, fix urls

Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

1 files changed, 24 insertions, 67 deletions

diff --git a/include/scsi/sg.h b/include/scsi/sg.h
index a9f3c6fc3f57..d8c0c4307fca 100644
--- a/include/scsi/sg.h
+++ b/include/scsi/sg.h
@@ -4,77 +4,34 @@
 #include <linux/compiler.h>
 
 /*
-   History:
-    Started: Aug 9 by Lawrence Foard (entropy@world.std.com), to allow user
-     process control of SCSI devices.
-    Development Sponsored by Killy Corp. NY NY
-Original driver (sg.h):
-*       Copyright (C) 1992 Lawrence Foard
-Version 2 and 3 extensions to driver:
-*       Copyright (C) 1998 - 2006 Douglas Gilbert
-
-    Version: 3.5.34 (20060920)
-    This version is for 2.6 series kernels.
-
-    For a full changelog see http://www.torque.net/sg
-
-Map of SG verions to the Linux kernels in which they appear:
-       ----------        ----------------------------------
-       original          all kernels < 2.2.6
-       2.1.40            2.2.20
-       3.0.x             optional version 3 sg driver for 2.2 series
-       3.1.17++          2.4.0++
-       3.5.30++          2.6.0++
-
-Major new features in SG 3.x driver (cf SG 2.x drivers)
-        - SG_IO ioctl() combines function if write() and read()
-        - new interface (sg_io_hdr_t) but still supports old interface
-        - scatter/gather in user space, direct IO, and mmap supported
-
- The normal action of this driver is to use the adapter (HBA) driver to DMA
- data into kernel buffers and then use the CPU to copy the data into the 
- user space (vice versa for writes). That is called "indirect" IO due to 
- the double handling of data. There are two methods offered to remove the
- redundant copy: 1) direct IO and 2) using the mmap() system call to map
- the reserve buffer (this driver has one reserve buffer per fd) into the
- user space. Both have their advantages.
- In terms of absolute speed mmap() is faster. If speed is not a concern, 
- indirect IO should be fine. Read the documentation for more information.
-
- ** N.B. To use direct IO 'echo 1 > /proc/scsi/sg/allow_dio' or
-         'echo 1 > /sys/module/sg/parameters/allow_dio' is needed.
-         That attribute is 0 by default. **
- 
- Historical note: this SCSI pass-through driver has been known as "sg" for 
- a decade. In broader kernel discussions "sg" is used to refer to scatter
- gather techniques. The context should clarify which "sg" is referred to.
-
- Documentation
- =============
- A web site for the SG device driver can be found at:
-        http://www.torque.net/sg  [alternatively check the MAINTAINERS file]
- The documentation for the sg version 3 driver can be found at:
-        http://www.torque.net/sg/p/sg_v3_ho.html
- This is a rendering from DocBook source [change the extension to "sgml"
- or "xml"]. There are renderings in "ps", "pdf", "rtf" and "txt" (soon).
- The SG_IO ioctl is now found in other parts kernel (e.g. the block layer).
- For more information see http://www.torque.net/sg/sg_io.html
-
- The older, version 2 documents discuss the original sg interface in detail:
-        http://www.torque.net/sg/p/scsi-generic.txt
-        http://www.torque.net/sg/p/scsi-generic_long.txt
- Also available: <kernel_source>/Documentation/scsi/scsi-generic.txt
-
- Utility and test programs are available at the sg web site. They are 
- packaged as sg3_utils (for the lk 2.4 and 2.6 series) and sg_utils
- (for the lk 2.2 series).
-*/
+ * History:
+ *  Started: Aug 9 by Lawrence Foard (entropy@world.std.com), to allow user
+ *   process control of SCSI devices.
+ *  Development Sponsored by Killy Corp. NY NY
+ *
+ * Original driver (sg.h):
+ *       Copyright (C) 1992 Lawrence Foard
+ * Version 2 and 3 extensions to driver:
+ *      Copyright (C) 1998 - 2014 Douglas Gilbert
+ *
+ *  Version: 3.5.36 (20140603)
+ *  This version is for 2.6 and 3 series kernels.
+ *
+ * Documentation
+ * =============
+ * A web site for the SG device driver can be found at:
+ *      http://sg.danny.cz/sg  [alternatively check the MAINTAINERS file]
+ * The documentation for the sg version 3 driver can be found at:
+ *      http://sg.danny.cz/sg/p/sg_v3_ho.html
+ * Also see: <kernel_source>/Documentation/scsi/scsi-generic.txt
+ *
+ * For utility and test programs see: http://sg.danny.cz/sg/sg3_utils.html
+ */
 
 #ifdef __KERNEL__
 extern int sg_big_buff; /* for sysctl */
 #endif
 
-/* New interface introduced in the 3.x SG drivers follows */
 
 typedef struct sg_iovec /* same structure as used by readv() Linux system */
 {                       /* call. It defines one scatter-gather element. */
@@ -87,7 +44,7 @@ typedef struct sg_io_hdr
 {
     int interface_id;           /* [i] 'S' for SCSI generic (required) */
     int dxfer_direction;        /* [i] data transfer direction  */
-    unsigned char cmd_len;      /* [i] SCSI command length ( <= 16 bytes) */
+    unsigned char cmd_len;      /* [i] SCSI command length */
     unsigned char mx_sb_len;    /* [i] max length to write to sbp */
     unsigned short iovec_count; /* [i] 0 implies no scatter gather */
     unsigned int dxfer_len;     /* [i] byte count of data transfer */