diff --git a/block.c b/block.c
index 00fe345..0aba1bf 100644
--- a/block.c
+++ b/block.c
@@ -44,7 +44,7 @@
 #include <windows.h>
 #endif
 
-static void bdrv_dev_change_cb(BlockDriverState *bs, int reason);
+static void bdrv_dev_change_media_cb(BlockDriverState *bs);
 static BlockDriverAIOCB *bdrv_aio_readv_em(BlockDriverState *bs,
         int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
         BlockDriverCompletionFunc *cb, void *opaque);
@@ -690,7 +690,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
 
     if (!bdrv_key_required(bs)) {
         bs->media_changed = 1;
-        bdrv_dev_change_cb(bs, CHANGE_MEDIA);
+        bdrv_dev_change_media_cb(bs);
     }
 
     return 0;
@@ -727,7 +727,7 @@ void bdrv_close(BlockDriverState *bs)
         }
 
         bs->media_changed = 1;
-        bdrv_dev_change_cb(bs, CHANGE_MEDIA);
+        bdrv_dev_change_media_cb(bs);
     }
 }
 
@@ -806,10 +806,17 @@ void bdrv_set_dev_ops(BlockDriverState *bs, const BlockDevOps *ops,
     bs->dev_opaque = opaque;
 }
 
-static void bdrv_dev_change_cb(BlockDriverState *bs, int reason)
+static void bdrv_dev_change_media_cb(BlockDriverState *bs)
 {
-    if (bs->dev_ops && bs->dev_ops->change_cb) {
-        bs->dev_ops->change_cb(bs->dev_opaque, reason);
+    if (bs->dev_ops && bs->dev_ops->change_media_cb) {
+        bs->dev_ops->change_media_cb(bs->dev_opaque);
+    }
+}
+
+static void bdrv_dev_resize_cb(BlockDriverState *bs)
+{
+    if (bs->dev_ops && bs->dev_ops->resize_cb) {
+        bs->dev_ops->resize_cb(bs->dev_opaque);
     }
 }
 
@@ -1283,7 +1290,7 @@ int bdrv_truncate(BlockDriverState *bs, int64_t offset)
     ret = drv->bdrv_truncate(bs, offset);
     if (ret == 0) {
         ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS);
-        bdrv_dev_change_cb(bs, CHANGE_SIZE);
+        bdrv_dev_resize_cb(bs);
     }
     return ret;
 }
@@ -1659,7 +1666,7 @@ int bdrv_set_key(BlockDriverState *bs, const char *key)
         bs->valid_key = 1;
         /* call the change callback now, we skipped it on open */
         bs->media_changed = 1;
-        bdrv_dev_change_cb(bs, CHANGE_MEDIA);
+        bdrv_dev_change_media_cb(bs);
     }
     return ret;
 }
diff --git a/block.h b/block.h
index a72cfc9..7e3f587 100644
--- a/block.h
+++ b/block.h
@@ -28,8 +28,18 @@ typedef struct QEMUSnapshotInfo {
     uint64_t vm_clock_nsec; /* VM clock relative to boot */
 } QEMUSnapshotInfo;
 
+/* Callbacks for block device models */
 typedef struct BlockDevOps {
-    void (*change_cb)(void *opaque, int reason);
+    /*
+     * Runs when virtual media changed (monitor commands eject, change)
+     * Beware: doesn't run when a host device's physical media
+     * changes.  Sure would be useful if it did.
+     */
+    void (*change_media_cb)(void *opaque);
+    /*
+     * Runs when the size changed (e.g. monitor command block_resize)
+     */
+    void (*resize_cb)(void *opaque);
 } BlockDevOps;
 
 #define BDRV_O_RDWR        0x0002
diff --git a/block_int.h b/block_int.h
index ab31dc9..19ae75e 100644
--- a/block_int.h
+++ b/block_int.h
@@ -211,9 +211,6 @@ struct BlockDriverState {
     void *private;
 };
 
-#define CHANGE_MEDIA    0x01
-#define CHANGE_SIZE     0x02
-
 struct BlockDriverAIOCB {
     AIOPool *pool;
     BlockDriverState *bs;
diff --git a/hw/ide/core.c b/hw/ide/core.c
index 26a9c5b..47a706e 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -783,15 +783,11 @@ static void ide_cfata_metadata_write(IDEState *s)
 }
 
 /* called when the inserted state of the media has changed */
-static void cdrom_change_cb(void *opaque, int reason)
+static void ide_cd_change_cb(void *opaque)
 {
     IDEState *s = opaque;
     uint64_t nb_sectors;
 
-    if (!(reason & CHANGE_MEDIA)) {
-        return;
-    }
-
     bdrv_get_geometry(s->bs, &nb_sectors);
     s->nb_sectors = nb_sectors;
 
@@ -1743,7 +1739,7 @@ void ide_bus_reset(IDEBus *bus)
 }
 
 static const BlockDevOps ide_cd_block_ops = {
-    .change_cb = cdrom_change_cb,
+    .change_media_cb = ide_cd_change_cb,
 };
 
 int ide_init_drive(IDEState *s, BlockDriverState *bs, IDEDriveKind kind,
diff --git a/hw/sd.c b/hw/sd.c
index 1f00910..45e95f9 100644
--- a/hw/sd.c
+++ b/hw/sd.c
@@ -420,14 +420,10 @@ static void sd_reset(SDState *sd, BlockDriverState *bdrv)
     sd->pwd_len = 0;
 }
 
-static void sd_cardchange(void *opaque, int reason)
+static void sd_cardchange(void *opaque)
 {
     SDState *sd = opaque;
 
-    if (!(reason & CHANGE_MEDIA)) {
-        return;
-    }
-
     qemu_set_irq(sd->inserted_cb, bdrv_is_inserted(sd->bdrv));
     if (bdrv_is_inserted(sd->bdrv)) {
         sd_reset(sd, sd->bdrv);
@@ -436,7 +432,7 @@ static void sd_cardchange(void *opaque, int reason)
 }
 
 static const BlockDevOps sd_block_ops = {
-    .change_cb = sd_cardchange,
+    .change_media_cb = sd_cardchange,
 };
 
 /* We do not model the chip select pin, so allow the board to select
diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index c10afa9..4df23f4 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -543,17 +543,15 @@ static int virtio_blk_load(QEMUFile *f, void *opaque, int version_id)
     return 0;
 }
 
-static void virtio_blk_change_cb(void *opaque, int reason)
+static void virtio_blk_resize(void *opaque)
 {
     VirtIOBlock *s = opaque;
 
-    if (reason & CHANGE_SIZE) {
-        virtio_notify_config(&s->vdev);
-    }
+    virtio_notify_config(&s->vdev);
 }
 
 static const BlockDevOps virtio_block_ops = {
-    .change_cb = virtio_blk_change_cb,
+    .resize_cb = virtio_blk_resize,
 };
 
 VirtIODevice *virtio_blk_init(DeviceState *dev, BlockConf *conf,
