block: extend BLOCK_IO_ERROR with reason string

BLOCK_IO_ERROR events are logged by libvirt, which helps with
post mortem analysis of guests. However, one information that
we miss today is a human readable string describing the cause
of the I/O error.

This commit adds that string it to BLOCK_IO_ERROR. Note that
this string is a debugging aid for humans, meaning that it
should not parsed by applications.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/block.c b/block.c
index dda5ae914d..bcd952a4cb 100644
--- a/block.c
+++ b/block.c
@@ -3647,7 +3647,8 @@ static void send_qmp_error_event(BlockDriverState *bs,
     ac = is_read ? IO_OPERATION_TYPE_READ : IO_OPERATION_TYPE_WRITE;
     qapi_event_send_block_io_error(bdrv_get_device_name(bs), ac, action,
                                    bdrv_iostatus_is_enabled(bs),
-                                   error == ENOSPC, &error_abort);
+                                   error == ENOSPC, strerror(error),
+                                   &error_abort);
 }
 
 /* This is done by device models because, while the block layer knows