scsi: remove scsi_end_request

By folding scsi_end_request into its only caller we can significantly clean
up the completion logic.  We can use simple goto labels now to only have
a single place to finish or requeue command there instead of the previous
convoluted logic.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nicholas Bellinger <nab@linux-iscsi.org>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Reviewed-by: Hannes Reinecke <hare@suse.de>

1 files changed, 32 insertions, 82 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index f416b5932a45..045822befad9 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -512,66 +512,6 @@ void scsi_run_host_queues(struct Scsi_Host *shost)
                 scsi_run_queue(sdev->request_queue);
 }
 
-/*
- * Function:    scsi_end_request()
- *
- * Purpose:     Post-processing of completed commands (usually invoked at end
- *              of upper level post-processing and scsi_io_completion).
- *
- * Arguments:   cmd      - command that is complete.
- *              error    - 0 if I/O indicates success, < 0 for I/O error.
- *              bytes    - number of bytes of completed I/O
- *              requeue  - indicates whether we should requeue leftovers.
- *
- * Lock status: Assumed that lock is not held upon entry.
- *
- * Returns:     cmd if requeue required, NULL otherwise.
- *
- * Notes:       This is called for block device requests in order to
- *              mark some number of sectors as complete.
- * 
- *              We are guaranteeing that the request queue will be goosed
- *              at some point during this call.
- * Notes:       If cmd was requeued, upon return it will be a stale pointer.
- */
-static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
-                                          int bytes, int requeue)
-{
-        struct request_queue *q = cmd->device->request_queue;
-        struct request *req = cmd->request;
-
-        /*
-         * If there are blocks left over at the end, set up the command
-         * to queue the remainder of them.
-         */
-        if (blk_end_request(req, error, bytes)) {
-                /* kill remainder if no retrys */
-                if (error && scsi_noretry_cmd(cmd))
-                        blk_end_request_all(req, error);
-                else {
-                        if (requeue) {
-                                /*
-                                 * Bleah.  Leftovers again.  Stick the
-                                 * leftovers in the front of the
-                                 * queue, and goose the queue again.
-                                 */
-                                scsi_release_buffers(cmd);
-                                scsi_requeue_command(q, cmd);
-                                cmd = NULL;
-                        }
-                        return cmd;
-                }
-        }
-
-        /*
-         * This will goose the queue request function at the end, so we don't
-         * need to worry about launching another command.
-         */
-        scsi_release_buffers(cmd);
-        scsi_next_command(cmd);
-        return NULL;
-}
-
 static inline unsigned int scsi_sgtable_index(unsigned short nents)
 {
         unsigned int index;
@@ -717,16 +657,9 @@ static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
  *
  * Returns:     Nothing
  *
- * Notes:       This function is matched in terms of capabilities to
- *              the function that created the scatter-gather list.
- *              In other words, if there are no bounce buffers
- *              (the normal case for most drivers), we don't need
- *              the logic to deal with cleaning up afterwards.
- *
- *              We must call scsi_end_request().  This will finish off
- *              the specified number of sectors.  If we are done, the
- *              command block will be released and the queue function
- *              will be goosed.  If we are not done then we have to
+ * Notes:       We will finish off the specified number of sectors.  If we
+ *              are done, the command block will be released and the queue
+ *              function will be goosed.  If we are not done then we have to
  *              figure out what to do next:
  *
  *              a) We can call scsi_requeue_command().  The request
@@ -735,7 +668,7 @@ static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
  *                 be used if we made forward progress, or if we want
  *                 to switch from READ(10) to READ(6) for example.
  *
- *              b) We can call scsi_queue_insert().  The request will
+ *              b) We can call __scsi_queue_insert().  The request will
  *                 be put back on the queue and retried using the same
  *                 command as before, possibly after a delay.
  *
@@ -794,6 +727,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 
                         scsi_release_buffers(cmd);
                         scsi_release_bidi_buffers(cmd);
+
                         blk_end_request_all(req, 0);
 
                         scsi_next_command(cmd);
@@ -833,12 +767,25 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
         }
 
         /*
-         * A number of bytes were successfully read.  If there
-         * are leftovers and there is some kind of error
-         * (result != 0), retry the rest.
+         * If we finished all bytes in the request we are done now.
          */
-        if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL)
-                return;
+        if (!blk_end_request(req, error, good_bytes))
+                goto next_command;
+
+        /*
+         * Kill remainder if no retrys.
+         */
+        if (error && scsi_noretry_cmd(cmd)) {
+                blk_end_request_all(req, error);
+                goto next_command;
+        }
+
+        /*
+         * If there had been no error, but we have leftover bytes in the
+         * requeues just queue the command up again.
+         */
+        if (result == 0)
+                goto requeue;
 
         error = __scsi_error_from_host_byte(cmd, result);
 
@@ -966,7 +913,6 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
         switch (action) {
         case ACTION_FAIL:
                 /* Give up and fail the remainder of the request */
-                scsi_release_buffers(cmd);
                 if (!(req->cmd_flags & REQ_QUIET)) {
                         if (description)
                                 scmd_printk(KERN_INFO, cmd, "%s\n",
@@ -976,12 +922,11 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
                                 scsi_print_sense("", cmd);
                         scsi_print_command(cmd);
                 }
-                if (blk_end_request_err(req, error))
-                        scsi_requeue_command(q, cmd);
-                else
-                        scsi_next_command(cmd);
-                break;
+                if (!blk_end_request_err(req, error))
+                        goto next_command;
+                /*FALLTHRU*/
         case ACTION_REPREP:
+        requeue:
                 /* Unprep the request and put it back at the head of the queue.
                  * A new command will be prepared and issued.
                  */
@@ -997,6 +942,11 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
                 __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
                 break;
         }
+        return;
+
+next_command:
+        scsi_release_buffers(cmd);
+        scsi_next_command(cmd);
 }
 
 static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,