usb-storage is for the most part just a wrapper around an internally
created scsi-disk device. It uses DEFINE_BLOCK_PROPERTIES() to offer all
of the usual block device properties to the user, but then only forwards
a few select properties to the internal device while the rest is
silently ignored.

This changes scsi_bus_legacy_add_drive() to accept a whole BlockConf
instead of some individual values inside of it so that usb-storage can
now pass the whole configuration to the internal scsi-disk. This enables
the remaining block device properties, e.g. logical/physical_block_size
or discard_granularity.

Buglink: https://issues.redhat.com/browse/RHEL-22375
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/hw/scsi/scsi.h       |  5 +----
 hw/scsi/scsi-bus.c           | 33 +++++++++++++--------------------
 hw/usb/dev-storage-classic.c |  5 +----
 3 files changed, 15 insertions(+), 28 deletions(-)

diff --git a/include/hw/scsi/scsi.h b/include/hw/scsi/scsi.h
index 10c4e8288d..c3d5e17e38 100644
--- a/include/hw/scsi/scsi.h
+++ b/include/hw/scsi/scsi.h
@@ -199,10 +199,7 @@ static inline SCSIBus *scsi_bus_from_device(SCSIDevice *d)
 }
 
 SCSIDevice *scsi_bus_legacy_add_drive(SCSIBus *bus, BlockBackend *blk,
-                                      int unit, bool removable, int bootindex,
-                                      bool share_rw,
-                                      BlockdevOnError rerror,
-                                      BlockdevOnError werror,
+                                      int unit, bool removable, BlockConf *conf,
                                       const char *serial, Error **errp);
 void scsi_bus_set_ua(SCSIBus *bus, SCSISense sense);
 void scsi_bus_legacy_handle_cmdline(SCSIBus *bus);
diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index 0a2eb11c56..f37737e6b6 100644
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -373,15 +373,13 @@ static void scsi_qdev_unrealize(DeviceState *qdev)
 
 /* handle legacy '-drive if=scsi,...' cmd line args */
 SCSIDevice *scsi_bus_legacy_add_drive(SCSIBus *bus, BlockBackend *blk,
-                                      int unit, bool removable, int bootindex,
-                                      bool share_rw,
-                                      BlockdevOnError rerror,
-                                      BlockdevOnError werror,
+                                      int unit, bool removable, BlockConf *conf,
                                       const char *serial, Error **errp)
 {
     const char *driver;
     char *name;
     DeviceState *dev;
+    SCSIDevice *s;
     DriveInfo *dinfo;
 
     if (blk_is_sg(blk)) {
@@ -399,11 +397,10 @@ SCSIDevice *scsi_bus_legacy_add_drive(SCSIBus *bus, BlockBackend *blk,
     object_property_add_child(OBJECT(bus), name, OBJECT(dev));
     g_free(name);
 
+    s = SCSI_DEVICE(dev);
+    s->conf = *conf;
+
     qdev_prop_set_uint32(dev, "scsi-id", unit);
-    if (bootindex >= 0) {
-        object_property_set_int(OBJECT(dev), "bootindex", bootindex,
-                                &error_abort);
-    }
     if (object_property_find(OBJECT(dev), "removable")) {
         qdev_prop_set_bit(dev, "removable", removable);
     }
@@ -414,19 +411,12 @@ SCSIDevice *scsi_bus_legacy_add_drive(SCSIBus *bus, BlockBackend *blk,
         object_unparent(OBJECT(dev));
         return NULL;
     }
-    if (!object_property_set_bool(OBJECT(dev), "share-rw", share_rw, errp)) {
-        object_unparent(OBJECT(dev));
-        return NULL;
-    }
-
-    qdev_prop_set_enum(dev, "rerror", rerror);
-    qdev_prop_set_enum(dev, "werror", werror);
 
     if (!qdev_realize_and_unref(dev, &bus->qbus, errp)) {
         object_unparent(OBJECT(dev));
         return NULL;
     }
-    return SCSI_DEVICE(dev);
+    return s;
 }
 
 void scsi_bus_legacy_handle_cmdline(SCSIBus *bus)
@@ -434,6 +424,12 @@ void scsi_bus_legacy_handle_cmdline(SCSIBus *bus)
     Location loc;
     DriveInfo *dinfo;
     int unit;
+    BlockConf conf = {
+        .bootindex = -1,
+        .share_rw = false,
+        .rerror = BLOCKDEV_ON_ERROR_AUTO,
+        .werror = BLOCKDEV_ON_ERROR_AUTO,
+    };
 
     loc_push_none(&loc);
     for (unit = 0; unit <= bus->info->max_target; unit++) {
@@ -443,10 +439,7 @@ void scsi_bus_legacy_handle_cmdline(SCSIBus *bus)
         }
         qemu_opts_loc_restore(dinfo->opts);
         scsi_bus_legacy_add_drive(bus, blk_by_legacy_dinfo(dinfo),
-                                  unit, false, -1, false,
-                                  BLOCKDEV_ON_ERROR_AUTO,
-                                  BLOCKDEV_ON_ERROR_AUTO,
-                                  NULL, &error_fatal);
+                                  unit, false, &conf, NULL, &error_fatal);
     }
     loc_pop(&loc);
 }
diff --git a/hw/usb/dev-storage-classic.c b/hw/usb/dev-storage-classic.c
index 84d19752b5..50a3ad6285 100644
--- a/hw/usb/dev-storage-classic.c
+++ b/hw/usb/dev-storage-classic.c
@@ -67,10 +67,7 @@ static void usb_msd_storage_realize(USBDevice *dev, Error **errp)
     scsi_bus_init(&s->bus, sizeof(s->bus), DEVICE(dev),
                  &usb_msd_scsi_info_storage);
     scsi_dev = scsi_bus_legacy_add_drive(&s->bus, blk, 0, !!s->removable,
-                                         s->conf.bootindex, s->conf.share_rw,
-                                         s->conf.rerror, s->conf.werror,
-                                         dev->serial,
-                                         errp);
+                                         &s->conf, dev->serial, errp);
     blk_unref(blk);
     if (!scsi_dev) {
         return;
-- 
2.43.0

Hi,

we got a user report about bootindex for an 'usb-storage' device not
working anymore [0] and I reproduced it and bisected it to this patch.

Am 31.01.24 um 14:06 schrieb Kevin Wolf:
> @@ -399,11 +397,10 @@ SCSIDevice *scsi_bus_legacy_add_drive(SCSIBus *bus, BlockBackend *blk,
>      object_property_add_child(OBJECT(bus), name, OBJECT(dev));
>      g_free(name);
>  
> +    s = SCSI_DEVICE(dev);
> +    s->conf = *conf;
> +
>      qdev_prop_set_uint32(dev, "scsi-id", unit);
> -    if (bootindex >= 0) {
> -        object_property_set_int(OBJECT(dev), "bootindex", bootindex,
> -                                &error_abort);
> -    }

The fact that this is not called anymore means that the 'set' method for
the property is also not called. Here, that method is
device_set_bootindex() (as configured by scsi_dev_instance_init() ->
device_add_bootindex_property()). Therefore, the device is never
registered via add_boot_device_path() meaning that the bootindex
property does not have the desired effect anymore.

Is it necessary to keep the object_property_set_{bool,int} and
qdev_prop_set_enum calls around for these potential side effects? Would
it even be necessary to introduce new similar calls for the newly
supported properties? Or is there an easy alternative to
s->conf = *conf;
that does trigger the side effects?

>      if (object_property_find(OBJECT(dev), "removable")) {
>          qdev_prop_set_bit(dev, "removable", removable);
>      }
> @@ -414,19 +411,12 @@ SCSIDevice *scsi_bus_legacy_add_drive(SCSIBus *bus, BlockBackend *blk,
>          object_unparent(OBJECT(dev));
>          return NULL;
>      }
> -    if (!object_property_set_bool(OBJECT(dev), "share-rw", share_rw, errp)) {
> -        object_unparent(OBJECT(dev));
> -        return NULL;
> -    }
> -
> -    qdev_prop_set_enum(dev, "rerror", rerror);
> -    qdev_prop_set_enum(dev, "werror", werror);
>  
>      if (!qdev_realize_and_unref(dev, &bus->qbus, errp)) {
>          object_unparent(OBJECT(dev));
>          return NULL;
>      }
> -    return SCSI_DEVICE(dev);
> +    return s;
>  }
>  
>  void scsi_bus_legacy_handle_cmdline(SCSIBus *bus)
[0]: https://forum.proxmox.com/threads/149772/post-679433

Best Regards,
Fiona

Am 01.07.2024 um 15:08 hat Fiona Ebner geschrieben:
> Hi,
> 
> we got a user report about bootindex for an 'usb-storage' device not
> working anymore [0] and I reproduced it and bisected it to this patch.
> 
> Am 31.01.24 um 14:06 schrieb Kevin Wolf:
> > @@ -399,11 +397,10 @@ SCSIDevice *scsi_bus_legacy_add_drive(SCSIBus *bus, BlockBackend *blk,
> >      object_property_add_child(OBJECT(bus), name, OBJECT(dev));
> >      g_free(name);
> >  
> > +    s = SCSI_DEVICE(dev);
> > +    s->conf = *conf;
> > +
> >      qdev_prop_set_uint32(dev, "scsi-id", unit);
> > -    if (bootindex >= 0) {
> > -        object_property_set_int(OBJECT(dev), "bootindex", bootindex,
> > -                                &error_abort);
> > -    }
> 
> The fact that this is not called anymore means that the 'set' method
> for the property is also not called. Here, that method is
> device_set_bootindex() (as configured by scsi_dev_instance_init() ->
> device_add_bootindex_property()). Therefore, the device is never
> registered via add_boot_device_path() meaning that the bootindex
> property does not have the desired effect anymore.

Hmm, yes, seem I missed this side effect.

Bringing back this one object_property_set_int() call would be the
easiest fix, but I wonder if an explicit add_boot_device_path() call
(and allowing that one to fail gracefully instead of directly calling
exit()) wouldn't be better than re-setting a property to its current
value just for the side effect.

> Is it necessary to keep the object_property_set_{bool,int} and
> qdev_prop_set_enum calls around for these potential side effects? Would
> it even be necessary to introduce new similar calls for the newly
> supported properties? Or is there an easy alternative to
> s->conf = *conf;
> that does trigger the side effects?

I don't think the other properties whose setter we don't call any more
have side effects. They are processed during .realize, which is what I
probably expected for bootindex, too.

And that's really how all properties should be if we ever want to move
forward with the .instance_config approach for creating QOM objects
because then we won't call any setters during object creation any more,
they would only be for runtime changes.

Kevin