[PATCH 07/13] scsi:scsi_error: Define helper to perform LUN based error handle

[Wenchao Hao <haowenchao2@huawei.com>]

Add an simple LUN based error handle strategy, it try lun based
recovery first, including check sense, start unit and reset lun.
If all above steps can not recovery all commands, fallback to
target or host based error handle.

This is an simple error handle strategy which can be used by drivers
or other LUN based error handlers.

Signed-off-by: Wenchao Hao <haowenchao2@huawei.com>
---
 drivers/scsi/scsi_error.c | 37 +++++++++++++++++++++++++++++++++++++
 include/scsi/scsi_eh.h    |  2 ++
 2 files changed, 39 insertions(+)

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 9fcfcc682b02..00da77f3f3f8 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -2494,6 +2494,43 @@ int scsi_error_handler(void *data)
 	return 0;
 }
 
+/*
+ * Single LUN error handle
+ *
+ * @work_q: list of scsi commands need to recovery
+ * @done_q: list of scsi commands handled
+ *
+ * return: return 1 if all commands in work_q is recoveryed, else 0 is returned
+ */
+int scsi_sdev_eh(struct scsi_device *sdev,
+		 struct list_head *work_q,
+		 struct list_head *done_q)
+{
+	int ret = 0;
+	struct scsi_cmnd *scmd;
+
+	SCSI_LOG_ERROR_RECOVERY(2, sdev_printk(KERN_INFO, sdev,
+		"%s:luneh: checking sense\n", current->comm));
+	ret = scsi_eh_get_sense(work_q, done_q);
+	if (ret)
+		return ret;
+
+	SCSI_LOG_ERROR_RECOVERY(2, sdev_printk(KERN_INFO, sdev,
+		"%s:luneh: start unit\n", current->comm));
+	scmd = list_first_entry(work_q, struct scsi_cmnd, eh_entry);
+	ret = scsi_eh_sdev_stu(scmd, work_q, done_q);
+	if (ret)
+		return ret;
+
+	SCSI_LOG_ERROR_RECOVERY(2, sdev_printk(KERN_INFO, sdev,
+		"%s:luneh reset LUN\n", current->comm));
+	scmd = list_first_entry(work_q, struct scsi_cmnd, eh_entry);
+	ret = scsi_eh_sdev_reset(scmd, work_q, done_q);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(scsi_sdev_eh);
+
 /*
  * Function:    scsi_report_bus_reset()
  *
diff --git a/include/scsi/scsi_eh.h b/include/scsi/scsi_eh.h
index 1ae08e81339f..030b22a8c164 100644
--- a/include/scsi/scsi_eh.h
+++ b/include/scsi/scsi_eh.h
@@ -18,6 +18,8 @@ extern int scsi_block_when_processing_errors(struct scsi_device *);
 extern bool scsi_command_normalize_sense(const struct scsi_cmnd *cmd,
 					 struct scsi_sense_hdr *sshdr);
 extern enum scsi_disposition scsi_check_sense(struct scsi_cmnd *);
+extern int scsi_sdev_eh(struct scsi_device *, struct list_head *,
+			struct list_head *);
 
 static inline bool scsi_sense_is_deferred(const struct scsi_sense_hdr *sshdr)
 {
-- 
2.35.3