block-backend.h currently contains a mix of functions:
some of them run under the BQL and modify the block layer graph,
others are instead thread-safe and perform I/O in iothreads.
It is not easy to understand which function is part of which
group (I/O vs GS), and this patch aims to clarify it.
The "GS" functions need the BQL, and often use
aio_context_acquire/release and/or drain to be sure they
can modify the graph safely.
The I/O function are instead thread safe, and can run in
any AioContext.
By splitting the header in two files, block-backend-io.h
and block-backend-global-state.h we have a clearer view on what
needs what kind of protection. block-backend-common.h
instead contains common structures shared by both headers.
In addition, remove "block/block.h" include as it seems
it is not necessary anymore, together with "qemu/iov.h"
block-backend.h is left there for legacy and to avoid changing
all includes in all c files that use the block-backend APIs.
Assertions are added in the next patch.
Signed-off-by: Emanuele Giuseppe Esposito
---
block/block-backend.c | 10 +-
include/sysemu/block-backend-common.h | 74 ++
include/sysemu/block-backend-global-state.h | 136 ++
include/sysemu/block-backend-io.h | 130 ++
include/sysemu/block-backend.h | 262 +---
5 files changed, 350 insertions(+), 262 deletions(-)
create mode 100644 include/sysemu/block-backend-common.h
create mode 100644 include/sysemu/block-backend-global-state.h
create mode 100644 include/sysemu/block-backend-io.h
diff --git a/block/block-backend.c b/block/block-backend.c
index deb55c272e..d31ae16b99 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -78,6 +78,7 @@ struct BlockBackend {
bool allow_aio_context_change;
bool allow_write_beyond_eof;
+/* Protected by BQL lock */
NotifierList remove_bs_notifiers, insert_bs_notifiers;
QLIST_HEAD(, BlockBackendAioNotifier) aio_notifiers;
@@ -110,12 +111,14 @@ static const AIOCBInfo block_backend_aiocb_info = {
static void drive_info_del(DriveInfo *dinfo);
static BlockBackend *bdrv_first_blk(BlockDriverState *bs);
-/* All BlockBackends */
+/* All BlockBackends. Protected by BQL lock. */
static QTAILQ_HEAD(, BlockBackend) block_backends =
QTAILQ_HEAD_INITIALIZER(block_backends);
-/* All BlockBackends referenced by the monitor and which are iterated through
by
- * blk_next() */
+/*
+ * All BlockBackends referenced by the monitor and which are iterated through
by
+ * blk_next(). Protected by BQL lock.
+ */
static QTAILQ_HEAD(, BlockBackend) monitor_block_backends =
QTAILQ_HEAD_INITIALIZER(monitor_block_backends);
@@ -985,6 +988,7 @@ BlockBackend *blk_by_dev(void *dev)
void blk_set_dev_ops(BlockBackend *blk, const BlockDevOps *ops,
void *opaque)
{
+g_assert(qemu_in_main_thread());
blk->dev_ops = ops;
blk->dev_opaque = opaque;
diff --git a/include/sysemu/block-backend-common.h
b/include/sysemu/block-backend-common.h
new file mode 100644
index 00..52ff6a4d26
--- /dev/null
+++ b/include/sysemu/block-backend-common.h
@@ -0,0 +1,74 @@
+/*
+ * QEMU Block backends
+ *
+ * Copyright (C) 2014-2016 Red Hat, Inc.
+ *
+ * Authors:
+ * Markus Armbruster ,
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1
+ * or later. See the COPYING.LIB file in the top-level directory.
+ */
+
+#ifndef BLOCK_BACKEND_COMMON_H
+#define BLOCK_BACKEND_COMMON_H
+
+#include "block/throttle-groups.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, Error **errp);
+/*
+ * 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);
+
