1 files changed, 172 insertions, 111 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index f5d3b96890d..940dc32ff0d 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -91,26 +91,19 @@ static void scsi_unprep_request(struct request *req)
 	scsi_put_command(cmd);
 }
 
-/*
- * Function:    scsi_queue_insert()
- *
- * Purpose:     Insert a command in the midlevel queue.
- *
- * Arguments:   cmd    - command that we are adding to queue.
- *              reason - why we are inserting command to queue.
- *
- * Lock status: Assumed that lock is not held upon entry.
- *
- * Returns:     Nothing.
- *
- * Notes:       We do this for one of two cases.  Either the host is busy
- *              and it cannot accept any more commands for the time being,
- *              or the device returned QUEUE_FULL and can accept no more
- *              commands.
- * Notes:       This could be called either from an interrupt context or a
- *              normal process context.
+/**
+ * __scsi_queue_insert - private queue insertion
+ * @cmd: The SCSI command being requeued
+ * @reason:  The reason for the requeue
+ * @unbusy: Whether the queue should be unbusied
+ *
+ * This is a private queue insertion.  The public interface
+ * scsi_queue_insert() always assumes the queue should be unbusied
+ * because it's always called before the completion.  This function is
+ * for a requeue after completion, which should only occur in this
+ * file.
  */
-int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
+static int __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
 {
 	struct Scsi_Host *host = cmd->device->host;
 	struct scsi_device *device = cmd->device;
@@ -150,7 +143,8 @@ int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
 	 * Decrement the counters, since these commands are no longer
 	 * active on the host/device.
 	 */
-	scsi_device_unbusy(device);
+	if (unbusy)
+		scsi_device_unbusy(device);
 
 	/*
 	 * Requeue this command.  It will go before all other commands
@@ -172,6 +166,29 @@ int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
 	return 0;
 }
 
+/*
+ * Function:    scsi_queue_insert()
+ *
+ * Purpose:     Insert a command in the midlevel queue.
+ *
+ * Arguments:   cmd    - command that we are adding to queue.
+ *              reason - why we are inserting command to queue.
+ *
+ * Lock status: Assumed that lock is not held upon entry.
+ *
+ * Returns:     Nothing.
+ *
+ * Notes:       We do this for one of two cases.  Either the host is busy
+ *              and it cannot accept any more commands for the time being,
+ *              or the device returned QUEUE_FULL and can accept no more
+ *              commands.
+ * Notes:       This could be called either from an interrupt context or a
+ *              normal process context.
+ */
+int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
+{
+	return __scsi_queue_insert(cmd, reason, 1);
+}
 /**
  * scsi_execute - insert request and wait for the result
  * @sdev:	scsi device
@@ -183,13 +200,15 @@ int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
  * @timeout:	request timeout in seconds
  * @retries:	number of times to retry request
  * @flags:	or into request flags;
+ * @resid:	optional residual length
  *
  * returns the req->errors value which is the scsi_cmnd result
  * field.
  */
 int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
 		 int data_direction, void *buffer, unsigned bufflen,
-		 unsigned char *sense, int timeout, int retries, int flags)
+		 unsigned char *sense, int timeout, int retries, int flags,
+		 int *resid)
 {
 	struct request *req;
 	int write = (data_direction == DMA_TO_DEVICE);
@@ -224,6 +243,8 @@ int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
 	if (unlikely(req->data_len > 0 && req->data_len <= bufflen))
 		memset(buffer + (bufflen - req->data_len), 0, req->data_len);
 
+	if (resid)
+		*resid = req->data_len;
 	ret = req->errors;
  out:
 	blk_put_request(req);
@@ -235,7 +256,8 @@ EXPORT_SYMBOL(scsi_execute);
 
 int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
 		     int data_direction, void *buffer, unsigned bufflen,
-		     struct scsi_sense_hdr *sshdr, int timeout, int retries)
+		     struct scsi_sense_hdr *sshdr, int timeout, int retries,
+		     int *resid)
 {
 	char *sense = NULL;
 	int result;
@@ -246,7 +268,7 @@ int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
 			return DRIVER_ERROR << 24;
 	}
 	result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
-			      sense, timeout, retries, 0);
+			      sense, timeout, retries, 0, resid);
 	if (sshdr)
 		scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
 
@@ -567,15 +589,18 @@ static inline int scsi_host_is_busy(struct Scsi_Host *shost)
  */
 static void scsi_run_queue(struct request_queue *q)
 {
-	struct scsi_device *starved_head = NULL, *sdev = q->queuedata;
+	struct scsi_device *sdev = q->queuedata;
 	struct Scsi_Host *shost = sdev->host;
+	LIST_HEAD(starved_list);
 	unsigned long flags;
 
 	if (scsi_target(sdev)->single_lun)
 		scsi_single_lun_run(sdev);
 
 	spin_lock_irqsave(shost->host_lock, flags);
-	while (!list_empty(&shost->starved_list) && !scsi_host_is_busy(shost)) {
+	list_splice_init(&shost->starved_list, &starved_list);
+
+	while (!list_empty(&starved_list)) {
 		int flagset;
 
 		/*
@@ -588,24 +613,18 @@ static void scsi_run_queue(struct request_queue *q)
 		 * scsi_request_fn must get the host_lock before checking
 		 * or modifying starved_list or starved_entry.
 		 */
-		sdev = list_entry(shost->starved_list.next,
-					  struct scsi_device, starved_entry);
-		/*
-		 * The *queue_ready functions can add a device back onto the
-		 * starved list's tail, so we must check for a infinite loop.
-		 */
-		if (sdev == starved_head)
+		if (scsi_host_is_busy(shost))
 			break;
-		if (!starved_head)
-			starved_head = sdev;
 
+		sdev = list_entry(starved_list.next,
+				  struct scsi_device, starved_entry);
+		list_del_init(&sdev->starved_entry);
 		if (scsi_target_is_busy(scsi_target(sdev))) {
 			list_move_tail(&sdev->starved_entry,
 				       &shost->starved_list);
 			continue;
 		}
 
-		list_del_init(&sdev->starved_entry);
 		spin_unlock(shost->host_lock);
 
 		spin_lock(sdev->request_queue->queue_lock);
@@ -621,6 +640,8 @@ static void scsi_run_queue(struct request_queue *q)
 
 		spin_lock(shost->host_lock);
 	}
+	/* put any unprocessed entries back */
+	list_splice(&starved_list, &shost->starved_list);
 	spin_unlock_irqrestore(shost->host_lock, flags);
 
 	blk_run_queue(q);
@@ -649,8 +670,8 @@ static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
 	struct request *req = cmd->request;
 	unsigned long flags;
 
-	scsi_unprep_request(req);
 	spin_lock_irqsave(q->queue_lock, flags);
+	scsi_unprep_request(req);
 	blk_requeue_request(q, req);
 	spin_unlock_irqrestore(q->queue_lock, flags);
 
@@ -680,6 +701,8 @@ void scsi_run_host_queues(struct Scsi_Host *shost)
 		scsi_run_queue(sdev->request_queue);
 }
 
+static void __scsi_release_buffers(struct scsi_cmnd *, int);
+
 /*
  * Function:    scsi_end_request()
  *
@@ -728,6 +751,7 @@ static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
 				 * leftovers in the front of the
 				 * queue, and goose the queue again.
 				 */
+				scsi_release_buffers(cmd);
 				scsi_requeue_command(q, cmd);
 				cmd = NULL;
 			}
@@ -739,6 +763,7 @@ static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
 	 * 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, 0);
 	scsi_next_command(cmd);
 	return NULL;
 }
@@ -794,6 +819,26 @@ static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
 	__sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);
 }
 
+static void __scsi_release_buffers(struct scsi_cmnd *cmd, int do_bidi_check)
+{
+
+	if (cmd->sdb.table.nents)
+		scsi_free_sgtable(&cmd->sdb);
+
+	memset(&cmd->sdb, 0, sizeof(cmd->sdb));
+
+	if (do_bidi_check && scsi_bidi_cmnd(cmd)) {
+		struct scsi_data_buffer *bidi_sdb =
+			cmd->request->next_rq->special;
+		scsi_free_sgtable(bidi_sdb);
+		kmem_cache_free(scsi_sdb_cache, bidi_sdb);
+		cmd->request->next_rq->special = NULL;
+	}
+
+	if (scsi_prot_sg_count(cmd))
+		scsi_free_sgtable(cmd->prot_sdb);
+}
+
 /*
  * Function:    scsi_release_buffers()
  *
@@ -813,21 +858,7 @@ static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
  */
 void scsi_release_buffers(struct scsi_cmnd *cmd)
 {
-	if (cmd->sdb.table.nents)
-		scsi_free_sgtable(&cmd->sdb);
-
-	memset(&cmd->sdb, 0, sizeof(cmd->sdb));
-
-	if (scsi_bidi_cmnd(cmd)) {
-		struct scsi_data_buffer *bidi_sdb =
-			cmd->request->next_rq->special;
-		scsi_free_sgtable(bidi_sdb);
-		kmem_cache_free(scsi_sdb_cache, bidi_sdb);
-		cmd->request->next_rq->special = NULL;
-	}
-
-	if (scsi_prot_sg_count(cmd))
-		scsi_free_sgtable(cmd->prot_sdb);
+	__scsi_release_buffers(cmd, 1);
 }
 EXPORT_SYMBOL(scsi_release_buffers);
 
@@ -876,16 +907,24 @@ static void scsi_end_bidi_request(struct scsi_cmnd *cmd)
  *              (the normal case for most drivers), we don't need
  *              the logic to deal with cleaning up afterwards.
  *
- *		We must do one of several things here:
+ *		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
+ *		figure out what to do next:
  *
- *		a) 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
- *		   scsi_end_request will directly goose the queue.
+ *		a) We can call scsi_requeue_command().  The request
+ *		   will be unprepared and put back on the queue.  Then
+ *		   a new command will be created for it.  This should
+ *		   be used if we made forward progress, or if we want
+ *		   to switch from READ(10) to READ(6) for example.
  *
- *		b) We can just use scsi_requeue_command() here.  This would
- *		   be used if we just wanted to retry, for example.
+ *		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.
+ *
+ *		c) We can call blk_end_request() with -EIO to fail
+ *		   the remainder of the request.
  */
 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 {
@@ -897,6 +936,9 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 	struct scsi_sense_hdr sshdr;
 	int sense_valid = 0;
 	int sense_deferred = 0;
+	enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY,
+	      ACTION_DELAYED_RETRY} action;
+	char *description = NULL;
 
 	if (result) {
 		sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
@@ -930,7 +972,6 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 	}
 
 	BUG_ON(blk_bidi_rq(req)); /* bidi not support for !blk_pc_request yet */
-	scsi_release_buffers(cmd);
 
 	/*
 	 * Next deal with any sectors which we were able to correctly
@@ -948,10 +989,15 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 		return;
 	this_count = blk_rq_bytes(req);
 
-	/* good_bytes = 0, or (inclusive) there were leftovers and
-	 * result = 0, so scsi_end_request couldn't retry.
-	 */
-	if (sense_valid && !sense_deferred) {
+	error = -EIO;
+
+	if (host_byte(result) == DID_RESET) {
+		/* Third party bus reset or reset for error recovery
+		 * reasons.  Just retry the command and see what
+		 * happens.
+		 */
+		action = ACTION_RETRY;
+	} else if (sense_valid && !sense_deferred) {
 		switch (sshdr.sense_key) {
 		case UNIT_ATTENTION:
 			if (cmd->device->removable) {
@@ -959,16 +1005,15 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 				 * and quietly refuse further access.
 				 */
 				cmd->device->changed = 1;
-				scsi_end_request(cmd, -EIO, this_count, 1);
-				return;
+				description = "Media Changed";
+				action = ACTION_FAIL;
 			} else {
 				/* Must have been a power glitch, or a
 				 * bus reset.  Could not have been a
 				 * media change, so we just retry the
-				 * request and see what happens.
+				 * command and see what happens.
 				 */
-				scsi_requeue_command(q, cmd);
-				return;
+				action = ACTION_RETRY;
 			}
 			break;
 		case ILLEGAL_REQUEST:
@@ -984,21 +1029,23 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 			    sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
 			    (cmd->cmnd[0] == READ_10 ||
 			     cmd->cmnd[0] == WRITE_10)) {
+				/* This will issue a new 6-byte command. */
 				cmd->device->use_10_for_rw = 0;
-				/* This will cause a retry with a
-				 * 6-byte command.
-				 */
-				scsi_requeue_command(q, cmd);
-			} else if (sshdr.asc == 0x10) /* DIX */
-				scsi_end_request(cmd, -EIO, this_count, 0);
-			else
-				scsi_end_request(cmd, -EIO, this_count, 1);
-			return;
+				action = ACTION_REPREP;
+			} else if (sshdr.asc == 0x10) /* DIX */ {
+				description = "Host Data Integrity Failure";
+				action = ACTION_FAIL;
+				error = -EILSEQ;
+			} else
+				action = ACTION_FAIL;
+			break;
 		case ABORTED_COMMAND:
 			if (sshdr.asc == 0x10) { /* DIF */
-				scsi_end_request(cmd, -EIO, this_count, 0);
-				return;
-			}
+				description = "Target Data Integrity Failure";
+				action = ACTION_FAIL;
+				error = -EILSEQ;
+			} else
+				action = ACTION_RETRY;
 			break;
 		case NOT_READY:
 			/* If the device is in the process of becoming
@@ -1013,49 +1060,63 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 				case 0x07: /* operation in progress */
 				case 0x08: /* Long write in progress */
 				case 0x09: /* self test in progress */
-					scsi_requeue_command(q, cmd);
-					return;
+					action = ACTION_DELAYED_RETRY;
+					break;
 				default:
+					description = "Device not ready";
+					action = ACTION_FAIL;
 					break;
 				}
+			} else {
+				description = "Device not ready";
+				action = ACTION_FAIL;
 			}
-			if (!(req->cmd_flags & REQ_QUIET))
-				scsi_cmd_print_sense_hdr(cmd,
-							 "Device not ready",
-							 &sshdr);
-
-			scsi_end_request(cmd, -EIO, this_count, 1);
-			return;
+			break;
 		case VOLUME_OVERFLOW:
-			if (!(req->cmd_flags & REQ_QUIET)) {
-				scmd_printk(KERN_INFO, cmd,
-					    "Volume overflow, CDB: ");
-				__scsi_print_command(cmd->cmnd);
-				scsi_print_sense("", cmd);
-			}
 			/* See SSC3rXX or current. */
-			scsi_end_request(cmd, -EIO, this_count, 1);
-			return;
+			action = ACTION_FAIL;
+			break;
 		default:
+			description = "Unhandled sense code";
+			action = ACTION_FAIL;
 			break;
 		}
+	} else {
+		description = "Unhandled error code";
+		action = ACTION_FAIL;
 	}
-	if (host_byte(result) == DID_RESET) {
-		/* Third party bus reset or reset for error recovery
-		 * reasons.  Just retry the request and see what
-		 * happens.
-		 */
-		scsi_requeue_command(q, cmd);
-		return;
-	}
-	if (result) {
+
+	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",
+					    description);
 			scsi_print_result(cmd);
 			if (driver_byte(result) & DRIVER_SENSE)
 				scsi_print_sense("", cmd);
 		}
+		blk_end_request(req, -EIO, blk_rq_bytes(req));
+		scsi_next_command(cmd);
+		break;
+	case ACTION_REPREP:
+		/* Unprep the request and put it back at the head of the queue.
+		 * A new command will be prepared and issued.
+		 */
+		scsi_release_buffers(cmd);
+		scsi_requeue_command(q, cmd);
+		break;
+	case ACTION_RETRY:
+		/* Retry the same command immediately */
+		__scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, 0);
+		break;
+	case ACTION_DELAYED_RETRY:
+		/* Retry the same command after a delay */
+		__scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
+		break;
 	}
-	scsi_end_request(cmd, -EIO, this_count, !result);
 }
 
 static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
@@ -1999,7 +2060,7 @@ scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
 	}
 
 	ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
-			       sshdr, timeout, retries);
+			       sshdr, timeout, retries, NULL);
 	kfree(real_buffer);
 	return ret;
 }
@@ -2064,7 +2125,7 @@ scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
 	memset(buffer, 0, len);
 
 	result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
-				  sshdr, timeout, retries);
+				  sshdr, timeout, retries, NULL);
 
 	/* This code looks awful: what it's doing is making sure an
 	 * ILLEGAL REQUEST sense return identifies the actual command
@@ -2146,7 +2207,7 @@ scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
 	/* try to eat the UNIT_ATTENTION if there are enough retries */
 	do {
 		result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
-					  timeout, retries);
+					  timeout, retries, NULL);
 		if (sdev->removable && scsi_sense_valid(sshdr) &&
 		    sshdr->sense_key == UNIT_ATTENTION)
 			sdev->changed = 1;