[SCSI] unify SCSI_IOCTL_SEND_COMMAND implementations

We currently have two implementations of this obsolete ioctl, one in
the block layer and one in the scsi code.  Both of them have drawbacks.

This patch kills the scsi layer version after updating the block version
with the missing bits:

 - argument checking
 - use scatterlist I/O
 - set number of retries based on the submitted command

This is the last user of non-S/G I/O except for the gdth driver, so
getting this in ASAP and through the scsi tree would be nie to kill
the non-S/G I/O path.  Jens, what do you think about adding a check
for non-S/G I/O in the midlayer?

Thanks to  Or Gerlitz for testing this patch.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 72 insertions, 29 deletions

diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index 24f7af9d0ab..b33eda26e20 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -350,16 +350,51 @@ out:
         return ret;
 }
 
+/**
+ * sg_scsi_ioctl  --  handle deprecated SCSI_IOCTL_SEND_COMMAND ioctl
+ * @file:       file this ioctl operates on (optional)
+ * @q:          request queue to send scsi commands down
+ * @disk:       gendisk to operate on (option)
+ * @sic:        userspace structure describing the command to perform
+ *
+ * Send down the scsi command described by @sic to the device below
+ * the request queue @q.  If @file is non-NULL it's used to perform
+ * fine-grained permission checks that allow users to send down
+ * non-destructive SCSI commands.  If the caller has a struct gendisk
+ * available it should be passed in as @disk to allow the low level
+ * driver to use the information contained in it.  A non-NULL @disk
+ * is only allowed if the caller knows that the low level driver doesn't
+ * need it (e.g. in the scsi subsystem).
+ *
+ * Notes:
+ *   -  This interface is deprecated - users should use the SG_IO
+ *      interface instead, as this is a more flexible approach to
+ *      performing SCSI commands on a device.
+ *   -  The SCSI command length is determined by examining the 1st byte
+ *      of the given command. There is no way to override this.
+ *   -  Data transfers are limited to PAGE_SIZE
+ *   -  The length (x + y) must be at least OMAX_SB_LEN bytes long to
+ *      accommodate the sense buffer when an error occurs.
+ *      The sense buffer is truncated to OMAX_SB_LEN (16) bytes so that
+ *      old code will not be surprised.
+ *   -  If a Unix error occurs (e.g. ENOMEM) then the user will receive
+ *      a negative return and the Unix error code in 'errno'.
+ *      If the SCSI command succeeds then 0 is returned.
+ *      Positive numbers returned are the compacted SCSI error codes (4
+ *      bytes in one int) where the lowest byte is the SCSI status.
+ */
 #define OMAX_SB_LEN 16          /* For backward compatibility */
-
-static int sg_scsi_ioctl(struct file *file, request_queue_t *q,
-                         struct gendisk *bd_disk, Scsi_Ioctl_Command __user *sic)
+int sg_scsi_ioctl(struct file *file, struct request_queue *q,
+                  struct gendisk *disk, struct scsi_ioctl_command __user *sic)
 {
         struct request *rq;
         int err;
         unsigned int in_len, out_len, bytes, opcode, cmdlen;
         char *buffer = NULL, sense[SCSI_SENSE_BUFFERSIZE];
 
+        if (!sic)
+                return -EINVAL;
+
         /*
          * get in an out lengths, verify they don't exceed a page worth of data
          */
@@ -393,45 +428,53 @@ static int sg_scsi_ioctl(struct file *file, request_queue_t *q,
         if (copy_from_user(rq->cmd, sic->data, cmdlen))
                 goto error;
 
-        if (copy_from_user(buffer, sic->data + cmdlen, in_len))
+        if (in_len && copy_from_user(buffer, sic->data + cmdlen, in_len))
                 goto error;
 
         err = verify_command(file, rq->cmd);
         if (err)
                 goto error;
 
+        /* default.  possible overriden later */
+        rq->retries = 5;
+
         switch (opcode) {
-                case SEND_DIAGNOSTIC:
-                case FORMAT_UNIT:
-                        rq->timeout = FORMAT_UNIT_TIMEOUT;
-                        break;
-                case START_STOP:
-                        rq->timeout = START_STOP_TIMEOUT;
-                        break;
-                case MOVE_MEDIUM:
-                        rq->timeout = MOVE_MEDIUM_TIMEOUT;
-                        break;
-                case READ_ELEMENT_STATUS:
-                        rq->timeout = READ_ELEMENT_STATUS_TIMEOUT;
-                        break;
-                case READ_DEFECT_DATA:
-                        rq->timeout = READ_DEFECT_DATA_TIMEOUT;
-                        break;
-                default:
-                        rq->timeout = BLK_DEFAULT_TIMEOUT;
-                        break;
+        case SEND_DIAGNOSTIC:
+        case FORMAT_UNIT:
+                rq->timeout = FORMAT_UNIT_TIMEOUT;
+                rq->retries = 1;
+                break;
+        case START_STOP:
+                rq->timeout = START_STOP_TIMEOUT;
+                break;
+        case MOVE_MEDIUM:
+                rq->timeout = MOVE_MEDIUM_TIMEOUT;
+                break;
+        case READ_ELEMENT_STATUS:
+                rq->timeout = READ_ELEMENT_STATUS_TIMEOUT;
+                break;
+        case READ_DEFECT_DATA:
+                rq->timeout = READ_DEFECT_DATA_TIMEOUT;
+                rq->retries = 1;
+                break;
+        default:
+                rq->timeout = BLK_DEFAULT_TIMEOUT;
+                break;
+        }
+
+        if (bytes && blk_rq_map_kern(q, rq, buffer, bytes, __GFP_WAIT)) {
+                err = DRIVER_ERROR << 24;
+                goto out;
         }
 
         memset(sense, 0, sizeof(sense));
         rq->sense = sense;
         rq->sense_len = 0;
-
-        rq->data = buffer;
-        rq->data_len = bytes;
         rq->flags |= REQ_BLOCK_PC;
-        rq->retries = 0;
 
-        blk_execute_rq(q, bd_disk, rq, 0);
+        blk_execute_rq(q, disk, rq, 0);
+
+out:
         err = rq->errors & 0xff;        /* only 8 bit SCSI status */
         if (err) {
                 if (rq->sense_len && rq->sense) {
@@ -450,7 +493,7 @@ error:
         blk_put_request(rq);
         return err;
 }
-
+EXPORT_SYMBOL_GPL(sg_scsi_ioctl);
 
 /* Send basic block requests */
 static int __blk_send_generic(request_queue_t *q, struct gendisk *bd_disk, int cmd, int data)