[Qemu-devel] [PATCH v2] scsi-disk: Don't enlarge min_io_size to max_io_size

[Fam Zheng <famz@redhat.com>]

Some backends report big max_io_sectors. Making min_io_size the same
value in this case will make it impossible for guest to align memory,
therefore the disk may not be usable at all.

Do not enlarge them when they are zero.

Reported-by: David Gibson <dgibson@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>

---

v2: Leave the values alone if zero. [Paolo]
    At least we can consult block layer for a slightly more sensible
    opt_io_size, but that's for another patch.
---
 hw/scsi/scsi-disk.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index f5ab767ab5..f8ed8cf2b4 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -714,10 +714,12 @@ static int scsi_disk_emulate_inquiry(SCSIRequest *req, uint8_t *outbuf)
 
                 /* min_io_size and opt_io_size can't be greater than
                  * max_io_sectors */
-                min_io_size =
-                    MIN_NON_ZERO(min_io_size, max_io_sectors);
-                opt_io_size =
-                    MIN_NON_ZERO(opt_io_size, max_io_sectors);
+                if (min_io_size) {
+                    min_io_size = MIN(min_io_size, max_io_sectors);
+                }
+                if (opt_io_size) {
+                    opt_io_size = MIN(opt_io_size, max_io_sectors);
+                }
             }
             /* required VPD size with unmap support */
             buflen = 0x40;
-- 
2.14.3