block: Fix virtual media change for if=none

BlockDriverState member removable controls whether virtual media
change (monitor commands change, eject) is allowed.  It is set when
the "type hint" is BDRV_TYPE_CDROM or BDRV_TYPE_FLOPPY.

The type hint is only set by drive_init().  It sets BDRV_TYPE_FLOPPY
for if=floppy.  It sets BDRV_TYPE_CDROM for media=cdrom and if=ide,
scsi, xen, or none.

if=ide and if=scsi work, because the type hint makes it a CD-ROM.
if=xen likewise, I think.

For the same reason, if=none works when it's used by ide-drive or
scsi-disk.  For other guest devices, there are problems:

* fdc: you can't change virtual media

    $ qemu [...] -drive if=none,id=foo,... -global isa-fdc.driveA=foo
    QEMU 0.12.50 monitor - type 'help' for more information
    (qemu) eject foo
    Device 'foo' is not removable

  unless you add media=cdrom, but that makes it readonly.

* virtio: if you add media=cdrom, you can change virtual media.  If
  you eject, the guest gets I/O errors.  If you change, the guest sees
  the drive's contents suddenly change.

* scsi-generic: if you add media=cdrom, you can change virtual media.
  I didn't test what that does to the guest or the physical device,
  but it can't be pretty.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block.c

@@ -1299,6 +1299,14 @@ BlockErrorAction bdrv_get_on_error(BlockDriverState *bs, int is_read)
     return is_read ? bs->on_read_error : bs->on_write_error;
 }
 
+void bdrv_set_removable(BlockDriverState *bs, int removable)
+{
+    bs->removable = removable;
+    if (removable && bs == bs_snapshots) {
+        bs_snapshots = NULL;
+    }
+}
+
 int bdrv_is_removable(BlockDriverState *bs)
 {
     return bs->removable;

block.h

@@ -162,6 +162,7 @@ int bdrv_get_translation_hint(BlockDriverState *bs);
 void bdrv_set_on_error(BlockDriverState *bs, BlockErrorAction on_read_error,
                        BlockErrorAction on_write_error);
 BlockErrorAction bdrv_get_on_error(BlockDriverState *bs, int is_read);
+void bdrv_set_removable(BlockDriverState *bs, int removable);
 int bdrv_is_removable(BlockDriverState *bs);
 int bdrv_is_read_only(BlockDriverState *bs);
 int bdrv_is_sg(BlockDriverState *bs);

hw/fdc.c

@@ -1847,10 +1847,16 @@ static void fdctrl_result_timer(void *opaque)
 static void fdctrl_connect_drives(FDCtrl *fdctrl)
 {
     unsigned int i;
+    FDrive *drive;
 
     for (i = 0; i < MAX_FD; i++) {
-        fd_init(&fdctrl->drives[i]);
-        fd_revalidate(&fdctrl->drives[i]);
+        drive = &fdctrl->drives[i];
+
+        fd_init(drive);
+        fd_revalidate(drive);
+        if (drive->bs) {
+            bdrv_set_removable(drive->bs, 1);
+        }
     }
 }
 

hw/ide/core.c

@@ -2629,6 +2629,7 @@ void ide_init_drive(IDEState *s, BlockDriverState *bs,
         pstrcpy(s->version, sizeof(s->version), QEMU_VERSION);
     }
     ide_reset(s);
+    bdrv_set_removable(bs, s->is_cdrom);
 }
 
 static void ide_init1(IDEBus *bus, int unit)

hw/scsi-disk.c

@@ -1049,6 +1049,7 @@ static void scsi_destroy(SCSIDevice *dev)
 static int scsi_disk_initfn(SCSIDevice *dev)
 {
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, dev);
+    int is_cd;
     DriveInfo *dinfo;
 
     if (!s->qdev.conf.bs) {
@@ -1056,6 +1057,7 @@ static int scsi_disk_initfn(SCSIDevice *dev)
         return -1;
     }
     s->bs = s->qdev.conf.bs;
+    is_cd = bdrv_get_type_hint(s->bs) == BDRV_TYPE_CDROM;
 
     if (!s->serial) {
         /* try to fall back to value set with legacy -drive serial=... */
@@ -1072,7 +1074,7 @@ static int scsi_disk_initfn(SCSIDevice *dev)
         return -1;
     }
 
-    if (bdrv_get_type_hint(s->bs) == BDRV_TYPE_CDROM) {
+    if (is_cd) {
         s->qdev.blocksize = 2048;
     } else {
         s->qdev.blocksize = s->qdev.conf.logical_block_size;
@@ -1081,6 +1083,7 @@ static int scsi_disk_initfn(SCSIDevice *dev)
 
     s->qdev.type = TYPE_DISK;
     qemu_add_vm_change_state_handler(scsi_dma_restart_cb, s);
+    bdrv_set_removable(s->bs, is_cd);
     return 0;
 }
 

hw/scsi-generic.c

@@ -509,6 +509,7 @@ static int scsi_generic_initfn(SCSIDevice *dev)
     DPRINTF("block size %d\n", s->qdev.blocksize);
     s->driver_status = 0;
     memset(s->sensebuf, 0, sizeof(s->sensebuf));
+    bdrv_set_removable(s->bs, 0);
     return 0;
 }
 

hw/virtio-blk.c

@@ -500,6 +500,7 @@ VirtIODevice *virtio_blk_init(DeviceState *dev, BlockConf *conf)
     qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);
     register_savevm("virtio-blk", virtio_blk_id++, 2,
                     virtio_blk_save, virtio_blk_load, s);
+    bdrv_set_removable(s->bs, 0);
 
     return &s->vdev;
 }