scsi: introduce scsi_sense_from_errno()

The new function is an extension of the switch statement in scsi-disk.c
which also includes the errno cases only found in sg_io_sense_from_errno.
This allows us to consolidate the errno handling.

Extracted from a patch by Hannes Reinecke <hare@suse.de>.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/scsi/utils.c b/scsi/utils.c
index 793c3a6..6b56e01 100644
--- a/scsi/utils.c
+++ b/scsi/utils.c
@@ -565,21 +565,52 @@
     return names[cmd];
 }
 
+int scsi_sense_from_errno(int errno_value, SCSISense *sense)
+{
+    switch (errno_value) {
+    case 0:
+        return GOOD;
+    case EDOM:
+        return TASK_SET_FULL;
+#ifdef CONFIG_LINUX
+        /* These errno mapping are specific to Linux.  For more information:
+         * - scsi_decide_disposition in drivers/scsi/scsi_error.c
+         * - scsi_result_to_blk_status in drivers/scsi/scsi_lib.c
+         * - blk_errors[] in block/blk-core.c
+         */
+    case EBADE:
+        return RESERVATION_CONFLICT;
+    case ENODATA:
+        *sense = SENSE_CODE(READ_ERROR);
+        return CHECK_CONDITION;
+    case EREMOTEIO:
+        *sense = SENSE_CODE(LUN_COMM_FAILURE);
+        return CHECK_CONDITION;
+#endif
+    case ENOMEDIUM:
+        *sense = SENSE_CODE(NO_MEDIUM);
+        return CHECK_CONDITION;
+    case ENOMEM:
+        *sense = SENSE_CODE(TARGET_FAILURE);
+        return CHECK_CONDITION;
+    case EINVAL:
+        *sense = SENSE_CODE(INVALID_FIELD);
+        return CHECK_CONDITION;
+    case ENOSPC:
+        *sense = SENSE_CODE(SPACE_ALLOC_FAILED);
+        return CHECK_CONDITION;
+    default:
+        *sense = SENSE_CODE(IO_ERROR);
+        return CHECK_CONDITION;
+    }
+}
+
 #ifdef CONFIG_LINUX
 int sg_io_sense_from_errno(int errno_value, struct sg_io_hdr *io_hdr,
                            SCSISense *sense)
 {
     if (errno_value != 0) {
-        switch (errno_value) {
-        case EDOM:
-            return TASK_SET_FULL;
-        case ENOMEM:
-            *sense = SENSE_CODE(TARGET_FAILURE);
-            return CHECK_CONDITION;
-        default:
-            *sense = SENSE_CODE(IO_ERROR);
-            return CHECK_CONDITION;
-        }
+        return scsi_sense_from_errno(errno_value, sense);
     } else {
         if (io_hdr->host_status == SG_ERR_DID_NO_CONNECT ||
             io_hdr->host_status == SG_ERR_DID_BUS_BUSY ||