[Qemu-devel] [PATCH v3 22/23] block: Lift device model API into BlockBackend

[Markus Armbruster <armbru@redhat.com>]

Move device model attachment / detachment and the BlockDevOps device
model callbacks and their wrappers from BlockDriverState to
BlockBackend.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 block.c                        | 126 ++++------------------------------
 block/block-backend.c          | 151 ++++++++++++++++++++++++++++++++++++++---
 block/qapi.c                   |   8 +--
 blockdev.c                     |   8 +--
 include/block/block.h          |  45 ------------
 include/block/block_int.h      |  12 ++--
 include/sysemu/block-backend.h |  35 ++++++++++
 7 files changed, 203 insertions(+), 182 deletions(-)

diff --git a/block.c b/block.c
index 1d9a680..fac1211 100644
--- a/block.c
+++ b/block.c
@@ -58,9 +58,6 @@ struct BdrvDirtyBitmap {
 
 #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
 
-#define COROUTINE_POOL_RESERVATION 64 /* number of coroutines to reserve */
-
-static void bdrv_dev_change_media_cb(BlockDriverState *bs, bool load);
 static BlockAIOCB *bdrv_aio_readv_em(BlockDriverState *bs,
         int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
         BlockCompletionFunc *cb, void *opaque);
@@ -1527,7 +1524,9 @@ int bdrv_open(BlockDriverState **pbs, const char *filename,
     }
 
     if (!bdrv_key_required(bs)) {
-        bdrv_dev_change_media_cb(bs, true);
+        if (bs->blk) {
+            blk_dev_change_media_cb(bs->blk, true);
+        }
     } else if (!runstate_check(RUN_STATE_PRELAUNCH)
                && !runstate_check(RUN_STATE_INMIGRATE)
                && !runstate_check(RUN_STATE_PAUSED)) { /* HACK */
@@ -1852,7 +1851,9 @@ void bdrv_close(BlockDriverState *bs)
         }
     }
 
-    bdrv_dev_change_media_cb(bs, false);
+    if (bs->blk) {
+        blk_dev_change_media_cb(bs->blk, false);
+    }
 
     /*throttling disk I/O limits*/
     if (bs->io_limits_enabled) {
@@ -1971,9 +1972,6 @@ static void bdrv_move_feature_fields(BlockDriverState *bs_dest,
     /* move some fields that need to stay attached to the device */
 
     /* dev info */
-    bs_dest->dev_ops            = bs_src->dev_ops;
-    bs_dest->dev_opaque         = bs_src->dev_opaque;
-    bs_dest->dev                = bs_src->dev;
     bs_dest->guest_block_size   = bs_src->guest_block_size;
     bs_dest->copy_on_read       = bs_src->copy_on_read;
 
@@ -2041,7 +2039,6 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
     assert(!bs_new->blk);
     assert(QLIST_EMPTY(&bs_new->dirty_bitmaps));
     assert(bs_new->job == NULL);
-    assert(bs_new->dev == NULL);
     assert(bs_new->io_limits_enabled == false);
     assert(!throttle_have_timer(&bs_new->throttle_state));
 
@@ -2058,7 +2055,6 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
     assert(!bs_new->blk);
 
     /* Check a few fields that should remain attached to the device */
-    assert(bs_new->dev == NULL);
     assert(bs_new->job == NULL);
     assert(bs_new->io_limits_enabled == false);
     assert(!throttle_have_timer(&bs_new->throttle_state));
@@ -2097,7 +2093,6 @@ void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top)
 
 static void bdrv_delete(BlockDriverState *bs)
 {
-    assert(!bs->dev);
     assert(!bs->job);
     assert(bdrv_op_blocker_is_empty(bs));
     assert(!bs->refcnt);
@@ -2111,105 +2106,6 @@ static void bdrv_delete(BlockDriverState *bs)
     g_free(bs);
 }
 
-int bdrv_attach_dev(BlockDriverState *bs, void *dev)
-/* TODO change to DeviceState *dev when all users are qdevified */
-{
-    if (bs->dev) {
-        return -EBUSY;
-    }
-    bs->dev = dev;
-    bdrv_iostatus_reset(bs);
-
-    /* We're expecting I/O from the device so bump up coroutine pool size */
-    qemu_coroutine_adjust_pool_size(COROUTINE_POOL_RESERVATION);
-    return 0;
-}
-
-/* TODO qdevified devices don't use this, remove when devices are qdevified */
-void bdrv_attach_dev_nofail(BlockDriverState *bs, void *dev)
-{
-    if (bdrv_attach_dev(bs, dev) < 0) {
-        abort();
-    }
-}
-
-void bdrv_detach_dev(BlockDriverState *bs, void *dev)
-/* TODO change to DeviceState *dev when all users are qdevified */
-{
-    assert(bs->dev == dev);
-    bs->dev = NULL;
-    bs->dev_ops = NULL;
-    bs->dev_opaque = NULL;
-    bs->guest_block_size = 512;
-    qemu_coroutine_adjust_pool_size(-COROUTINE_POOL_RESERVATION);
-}
-
-/* TODO change to return DeviceState * when all users are qdevified */
-void *bdrv_get_attached_dev(BlockDriverState *bs)
-{
-    return bs->dev;
-}
-
-void bdrv_set_dev_ops(BlockDriverState *bs, const BlockDevOps *ops,
-                      void *opaque)
-{
-    bs->dev_ops = ops;
-    bs->dev_opaque = opaque;
-}
-
-static void bdrv_dev_change_media_cb(BlockDriverState *bs, bool load)
-{
-    if (bs->dev_ops && bs->dev_ops->change_media_cb) {
-        bool tray_was_closed = !bdrv_dev_is_tray_open(bs);
-        bs->dev_ops->change_media_cb(bs->dev_opaque, load);
-        if (tray_was_closed) {
-            /* tray open */
-            qapi_event_send_device_tray_moved(bdrv_get_device_name(bs),
-                                              true, &error_abort);
-        }
-        if (load) {
-            /* tray close */
-            qapi_event_send_device_tray_moved(bdrv_get_device_name(bs),
-                                              false, &error_abort);
-        }
-    }
-}
-
-bool bdrv_dev_has_removable_media(BlockDriverState *bs)
-{
-    return !bs->dev || (bs->dev_ops && bs->dev_ops->change_media_cb);
-}
-
-void bdrv_dev_eject_request(BlockDriverState *bs, bool force)
-{
-    if (bs->dev_ops && bs->dev_ops->eject_request_cb) {
-        bs->dev_ops->eject_request_cb(bs->dev_opaque, force);
-    }
-}
-
-bool bdrv_dev_is_tray_open(BlockDriverState *bs)
-{
-    if (bs->dev_ops && bs->dev_ops->is_tray_open) {
-        return bs->dev_ops->is_tray_open(bs->dev_opaque);
-    }
-    return false;
-}
-
-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);
-    }
-}
-
-bool bdrv_dev_is_medium_locked(BlockDriverState *bs)
-{
-    if (bs->dev_ops && bs->dev_ops->is_medium_locked) {
-        return bs->dev_ops->is_medium_locked(bs->dev_opaque);
-    }
-    return false;
-}
-
 /*
  * Run consistency checks on an image
  *
@@ -3543,7 +3439,9 @@ 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_resize_cb(bs);
+        if (bs->blk) {
+            blk_dev_resize_cb(bs->blk);
+        }
     }
     return ret;
 }
@@ -3744,8 +3642,10 @@ int bdrv_set_key(BlockDriverState *bs, const char *key)
         bs->valid_key = 0;
     } else if (!bs->valid_key) {
         bs->valid_key = 1;
-        /* call the change callback now, we skipped it on open */
-        bdrv_dev_change_media_cb(bs, true);
+        if (bs->blk) {
+            /* call the change callback now, we skipped it on open */
+            blk_dev_change_media_cb(bs->blk, true);
+        }
     }
     return ret;
 }
diff --git a/block/block-backend.c b/block/block-backend.c
index b55f0b4..d49c988 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -13,6 +13,10 @@
 #include "sysemu/block-backend.h"
 #include "block/block_int.h"
 #include "sysemu/blockdev.h"
+#include "qapi-event.h"
+
+/* Number of coroutines to reserve per attached device model */
+#define COROUTINE_POOL_RESERVATION 64
 
 struct BlockBackend {
     char *name;
@@ -20,6 +24,11 @@ struct BlockBackend {
     BlockDriverState *bs;
     DriveInfo *legacy_dinfo;
     QTAILQ_ENTRY(BlockBackend) link; /* for blk_backends */
+
+    void *dev;                  /* attached device model, if any */
+    /* TODO change to DeviceState when all users are qdevified */
+    const BlockDevOps *dev_ops;
+    void *dev_opaque;
 };
 
 static void drive_info_del(DriveInfo *dinfo);
@@ -81,6 +90,7 @@ BlockBackend *blk_new_with_bs(const char *name, Error **errp)
 static void blk_delete(BlockBackend *blk)
 {
     assert(!blk->refcnt);
+    assert(!blk->dev);
     if (blk->bs) {
         assert(blk->bs->blk == blk);
         blk->bs->blk = NULL;
@@ -233,34 +243,153 @@ void blk_hide_on_behalf_of_do_drive_del(BlockBackend *blk)
     }
 }
 
-void blk_iostatus_enable(BlockBackend *blk)
-{
-    bdrv_iostatus_enable(blk->bs);
-}
-
+/*
+ * Attach device model @dev to @blk.
+ * Return 0 on success, -EBUSY when a device model is attached already.
+ */
 int blk_attach_dev(BlockBackend *blk, void *dev)
+/* TODO change to DeviceState *dev when all users are qdevified */
 {
-    return bdrv_attach_dev(blk->bs, dev);
+    if (blk->dev) {
+        return -EBUSY;
+    }
+    blk->dev = dev;
+    bdrv_iostatus_reset(blk->bs);
+
+    /* We're expecting I/O from the device so bump up coroutine pool size */
+    qemu_coroutine_adjust_pool_size(COROUTINE_POOL_RESERVATION);
+    return 0;
 }
 
+/*
+ * Attach device model @dev to @blk.
+ * @blk must not have a device model attached already.
+ * TODO qdevified devices don't use this, remove when devices are qdevified
+ */
 void blk_attach_dev_nofail(BlockBackend *blk, void *dev)
 {
-    bdrv_attach_dev_nofail(blk->bs, dev);
+    if (blk_attach_dev(blk, dev) < 0) {
+        abort();
+    }
 }
 
+/*
+ * Detach device model @dev from @blk.
+ * @dev must be currently attached to @blk.
+ */
 void blk_detach_dev(BlockBackend *blk, void *dev)
+/* TODO change to DeviceState *dev when all users are qdevified */
 {
-    bdrv_detach_dev(blk->bs, dev);
+    assert(blk->dev == dev);
+    blk->dev = NULL;
+    blk->dev_ops = NULL;
+    blk->dev_opaque = NULL;
+    bdrv_set_guest_block_size(blk->bs, 512);
+    qemu_coroutine_adjust_pool_size(-COROUTINE_POOL_RESERVATION);
 }
 
+/*
+ * Return the device model attached to @blk if any, else null.
+ */
 void *blk_get_attached_dev(BlockBackend *blk)
+/* TODO change to return DeviceState * when all users are qdevified */
 {
-    return bdrv_get_attached_dev(blk->bs);
+    return blk->dev;
 }
 
-void blk_set_dev_ops(BlockBackend *blk, const BlockDevOps *ops, void *opaque)
+/*
+ * Set @blk's device model callbacks to @ops.
+ * @opaque is the opaque argument to pass to the callbacks.
+ * This is for use by device models.
+ */
+void blk_set_dev_ops(BlockBackend *blk, const BlockDevOps *ops,
+                     void *opaque)
 {
-    bdrv_set_dev_ops(blk->bs, ops, opaque);
+    blk->dev_ops = ops;
+    blk->dev_opaque = opaque;
+}
+
+/*
+ * Notify @blk's attached device model of media change.
+ * If @load is true, notify of media load.
+ * Else, notify of media eject.
+ * Also send DEVICE_TRAY_MOVED events as appropriate.
+ */
+void blk_dev_change_media_cb(BlockBackend *blk, bool load)
+{
+    if (blk->dev_ops && blk->dev_ops->change_media_cb) {
+        bool tray_was_closed = !blk_dev_is_tray_open(blk);
+
+        blk->dev_ops->change_media_cb(blk->dev_opaque, load);
+        if (tray_was_closed) {
+            /* tray open */
+            qapi_event_send_device_tray_moved(blk_name(blk),
+                                              true, &error_abort);
+        }
+        if (load) {
+            /* tray close */
+            qapi_event_send_device_tray_moved(blk_name(blk),
+                                              false, &error_abort);
+        }
+    }
+}
+
+/*
+ * Does @blk's attached device model have removable media?
+ * %true if no device model is attached.
+ */
+bool blk_dev_has_removable_media(BlockBackend *blk)
+{
+    return !blk->dev || (blk->dev_ops && blk->dev_ops->change_media_cb);
+}
+
+/*
+ * Notify @blk's attached device model of a media eject request.
+ * If @force is true, the medium is about to be yanked out forcefully.
+ */
+void blk_dev_eject_request(BlockBackend *blk, bool force)
+{
+    if (blk->dev_ops && blk->dev_ops->eject_request_cb) {
+        blk->dev_ops->eject_request_cb(blk->dev_opaque, force);
+    }
+}
+
+/*
+ * Does @blk's attached device model have a tray, and is it open?
+ */
+bool blk_dev_is_tray_open(BlockBackend *blk)
+{
+    if (blk->dev_ops && blk->dev_ops->is_tray_open) {
+        return blk->dev_ops->is_tray_open(blk->dev_opaque);
+    }
+    return false;
+}
+
+/*
+ * Does @blk's attached device model have the medium locked?
+ * %false if the device model has no such lock.
+ */
+bool blk_dev_is_medium_locked(BlockBackend *blk)
+{
+    if (blk->dev_ops && blk->dev_ops->is_medium_locked) {
+        return blk->dev_ops->is_medium_locked(blk->dev_opaque);
+    }
+    return false;
+}
+
+/*
+ * Notify @blk's attached device model of a backend size change.
+ */
+void blk_dev_resize_cb(BlockBackend *blk)
+{
+    if (blk->dev_ops && blk->dev_ops->resize_cb) {
+        blk->dev_ops->resize_cb(blk->dev_opaque);
+    }
+}
+
+void blk_iostatus_enable(BlockBackend *blk)
+{
+    bdrv_iostatus_enable(blk->bs);
 }
 
 int blk_read(BlockBackend *blk, int64_t sector_num, uint8_t *buf,
diff --git a/block/qapi.c b/block/qapi.c
index fca981d..1301144 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -275,12 +275,12 @@ static void bdrv_query_info(BlockBackend *blk, BlockInfo **p_info,
     Error *local_err = NULL;
     info->device = g_strdup(blk_name(blk));
     info->type = g_strdup("unknown");
-    info->locked = bdrv_dev_is_medium_locked(bs);
-    info->removable = bdrv_dev_has_removable_media(bs);
+    info->locked = blk_dev_is_medium_locked(blk);
+    info->removable = blk_dev_has_removable_media(blk);
 
-    if (bdrv_dev_has_removable_media(bs)) {
+    if (blk_dev_has_removable_media(blk)) {
         info->has_tray_open = true;
-        info->tray_open = bdrv_dev_is_tray_open(bs);
+        info->tray_open = blk_dev_is_tray_open(blk);
     }
 
     if (bdrv_iostatus_is_enabled(bs)) {
diff --git a/blockdev.c b/blockdev.c
index e115bde..d3dccb9 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1509,14 +1509,14 @@ static void eject_device(BlockBackend *blk, int force, Error **errp)
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_EJECT, errp)) {
         return;
     }
-    if (!bdrv_dev_has_removable_media(bs)) {
+    if (!blk_dev_has_removable_media(blk)) {
         error_setg(errp, "Device '%s' is not removable",
                    bdrv_get_device_name(bs));
         return;
     }
 
-    if (bdrv_dev_is_medium_locked(bs) && !bdrv_dev_is_tray_open(bs)) {
-        bdrv_dev_eject_request(bs, force);
+    if (blk_dev_is_medium_locked(blk) && !blk_dev_is_tray_open(blk)) {
+        blk_dev_eject_request(blk, force);
         if (!force) {
             error_setg(errp, "Device '%s' is locked",
                        bdrv_get_device_name(bs));
@@ -1753,7 +1753,7 @@ int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data)
      * can be removed.  If this is a drive with no device backing
      * then we can just get rid of the block driver state right here.
      */
-    if (bdrv_get_attached_dev(bs)) {
+    if (blk_get_attached_dev(blk)) {
         blk_hide_on_behalf_of_do_drive_del(blk);
         /* Further I/O must not pause the guest */
         bdrv_set_on_error(bs, BLOCKDEV_ON_ERROR_REPORT,
diff --git a/include/block/block.h b/include/block/block.h
index 5b45743..bc9ec50 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -48,41 +48,6 @@ typedef struct BlockFragInfo {
     uint64_t compressed_clusters;
 } BlockFragInfo;
 
-/* Callbacks for block device models */
-typedef struct BlockDevOps {
-    /*
-     * Runs when virtual media changed (monitor commands eject, change)
-     * Argument load is true on load and false on eject.
-     * Beware: doesn't run when a host device's physical media
-     * changes.  Sure would be useful if it did.
-     * Device models with removable media must implement this callback.
-     */
-    void (*change_media_cb)(void *opaque, bool load);
-    /*
-     * Runs when an eject request is issued from the monitor, the tray
-     * is closed, and the medium is locked.
-     * Device models that do not implement is_medium_locked will not need
-     * this callback.  Device models that can lock the medium or tray might
-     * want to implement the callback and unlock the tray when "force" is
-     * true, even if they do not support eject requests.
-     */
-    void (*eject_request_cb)(void *opaque, bool force);
-    /*
-     * Is the virtual tray open?
-     * Device models implement this only when the device has a tray.
-     */
-    bool (*is_tray_open)(void *opaque);
-    /*
-     * Is the virtual medium locked into the device?
-     * Device models implement this only when device has such a lock.
-     */
-    bool (*is_medium_locked)(void *opaque);
-    /*
-     * Runs when the size changed (e.g. monitor command block_resize)
-     */
-    void (*resize_cb)(void *opaque);
-} BlockDevOps;
-
 typedef enum {
     BDRV_REQ_COPY_ON_READ = 0x1,
     BDRV_REQ_ZERO_WRITE   = 0x2,
@@ -230,16 +195,6 @@ void bdrv_reopen_commit(BDRVReopenState *reopen_state);
 void bdrv_reopen_abort(BDRVReopenState *reopen_state);
 void bdrv_close(BlockDriverState *bs);
 void bdrv_add_close_notifier(BlockDriverState *bs, Notifier *notify);
-int bdrv_attach_dev(BlockDriverState *bs, void *dev);
-void bdrv_attach_dev_nofail(BlockDriverState *bs, void *dev);
-void bdrv_detach_dev(BlockDriverState *bs, void *dev);
-void *bdrv_get_attached_dev(BlockDriverState *bs);
-void bdrv_set_dev_ops(BlockDriverState *bs, const BlockDevOps *ops,
-                      void *opaque);
-void bdrv_dev_eject_request(BlockDriverState *bs, bool force);
-bool bdrv_dev_has_removable_media(BlockDriverState *bs);
-bool bdrv_dev_is_tray_open(BlockDriverState *bs);
-bool bdrv_dev_is_medium_locked(BlockDriverState *bs);
 int bdrv_read(BlockDriverState *bs, int64_t sector_num,
               uint8_t *buf, int nb_sectors);
 int bdrv_read_unthrottled(BlockDriverState *bs, int64_t sector_num,
diff --git a/include/block/block_int.h b/include/block/block_int.h
index e8e33a8..8898c6c 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -326,11 +326,6 @@ struct BlockDriverState {
 
     BlockBackend *blk;          /* owning backend, if any */
 
-    void *dev;                  /* attached device model, if any */
-    /* TODO change to DeviceState when all users are qdevified */
-    const BlockDevOps *dev_ops;
-    void *dev_opaque;
-
     AioContext *aio_context; /* event loop used for fd handlers, timers, etc */
     /* long-running tasks intended to always use the same AioContext as this
      * BDS may register themselves in this list to be notified of changes
@@ -587,4 +582,11 @@ void backup_start(BlockDriverState *bs, BlockDriverState *target,
                   BlockCompletionFunc *cb, void *opaque,
                   Error **errp);
 
+void blk_dev_change_media_cb(BlockBackend *blk, bool load);
+bool blk_dev_has_removable_media(BlockBackend *blk);
+void blk_dev_eject_request(BlockBackend *blk, bool force);
+bool blk_dev_is_tray_open(BlockBackend *blk);
+bool blk_dev_is_medium_locked(BlockBackend *blk);
+void blk_dev_resize_cb(BlockBackend *blk);
+
 #endif /* BLOCK_INT_H */
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index e4bfea5..02305a1 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -25,6 +25,41 @@
  */
 #include "block/block.h"
 
+/* Callbacks for block device models */
+typedef struct BlockDevOps {
+    /*
+     * Runs when virtual media changed (monitor commands eject, change)
+     * Argument load is true on load and false on eject.
+     * Beware: doesn't run when a host device's physical media
+     * changes.  Sure would be useful if it did.
+     * Device models with removable media must implement this callback.
+     */
+    void (*change_media_cb)(void *opaque, bool load);
+    /*
+     * Runs when an eject request is issued from the monitor, the tray
+     * is closed, and the medium is locked.
+     * Device models that do not implement is_medium_locked will not need
+     * this callback.  Device models that can lock the medium or tray might
+     * want to implement the callback and unlock the tray when "force" is
+     * true, even if they do not support eject requests.
+     */
+    void (*eject_request_cb)(void *opaque, bool force);
+    /*
+     * Is the virtual tray open?
+     * Device models implement this only when the device has a tray.
+     */
+    bool (*is_tray_open)(void *opaque);
+    /*
+     * Is the virtual medium locked into the device?
+     * Device models implement this only when device has such a lock.
+     */
+    bool (*is_medium_locked)(void *opaque);
+    /*
+     * Runs when the size changed (e.g. monitor command block_resize)
+     */
+    void (*resize_cb)(void *opaque);
+} BlockDevOps;
+
 BlockBackend *blk_new(const char *name, Error **errp);
 BlockBackend *blk_new_with_bs(const char *name, Error **errp);
 void blk_ref(BlockBackend *blk);
-- 
1.9.3