[PATCH 5/5] iscsi: avoid null iSCSI error strings after cancel or timeout

[Konstantin Nigmatullin <rangolit@gmail.com>]

Cancelled and timed-out tasks often left err_str unset, so logs printed
"(null)" instead of a useful reason.

See: https://gitlab.com/qemu-project/qemu/-/work_items/3067
Signed-off-by: Konstantin Nigmatullin <rangolit@gmail.com>
---
 block/iscsi.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/block/iscsi.c b/block/iscsi.c
index b6207d03e5..0ab12987b8 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -290,6 +290,20 @@ iscsi_co_generic_cb(struct iscsi_context *iscsi, int status,
         iscsilun->nop_failures = 0;
     }
 
+    if (status != SCSI_STATUS_GOOD && !iTask->do_retry && !iTask->err_str) {
+        const char *e = iscsi_get_error(iscsi);
+
+        if (e && e[0]) {
+            iTask->err_str = g_strdup(e);
+        } else if (status == SCSI_STATUS_CANCELLED) {
+            iTask->err_str = g_strdup("task cancelled");
+        } else if (status == SCSI_STATUS_TIMEOUT) {
+            iTask->err_str = g_strdup("command timed out");
+        } else {
+            iTask->err_str = g_strdup("I/O error");
+        }
+    }
+
     /*
      * aio_co_wake() is safe to call: iscsi_service(), which called us, is only
      * run from the event_timer and/or the FD handlers, never from the request
-- 
2.53.0