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[Qemu-devel] [PATCH 3/8] block: implement reference count for BlockDrive
From: |
Fam Zheng |
Subject: |
[Qemu-devel] [PATCH 3/8] block: implement reference count for BlockDriverState |
Date: |
Thu, 25 Jul 2013 17:01:41 +0800 |
Introduce bdrv_ref/bdrv_unref to manage the lifecycle of
BlockDriverState. They are unused for now but will used to replace
bdrv_delete() later.
Signed-off-by: Fam Zheng <address@hidden>
---
block.c | 22 ++++++++++++++++++++++
include/block/block.h | 2 ++
include/block/block_int.h | 1 +
3 files changed, 25 insertions(+)
diff --git a/block.c b/block.c
index 6cd39fa..6f7ad7f 100644
--- a/block.c
+++ b/block.c
@@ -306,6 +306,7 @@ BlockDriverState *bdrv_new(const char *device_name)
bdrv_iostatus_disable(bs);
notifier_list_init(&bs->close_notifiers);
notifier_with_return_list_init(&bs->before_write_notifiers);
+ bs->refcnt = 1;
return bs;
}
@@ -1511,6 +1512,9 @@ static void bdrv_move_feature_fields(BlockDriverState
*bs_dest,
/* dirty bitmap */
bs_dest->dirty_bitmap = bs_src->dirty_bitmap;
+ /* reference count */
+ bs_dest->refcnt = bs_src->refcnt;
+
/* job */
bs_dest->in_use = bs_src->in_use;
bs_dest->job = bs_src->job;
@@ -4385,6 +4389,24 @@ int64_t bdrv_get_dirty_count(BlockDriverState *bs)
}
}
+/* Get a reference to bs */
+void bdrv_ref(BlockDriverState *bs)
+{
+ bs->refcnt++;
+}
+
+/* Release a previously grabbed reference to bs.
+ * If after releasing, reference count is zero, the BlockDriverState is
+ * deleted. */
+void bdrv_unref(BlockDriverState *bs)
+{
+ assert(bs->refcnt > 0);
+ if (--bs->refcnt == 0) {
+ bdrv_close(bs);
+ bdrv_delete(bs);
+ }
+}
+
void bdrv_set_in_use(BlockDriverState *bs, int in_use)
{
assert(bs->in_use != in_use);
diff --git a/include/block/block.h b/include/block/block.h
index 742fce5..b33ef62 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -356,6 +356,8 @@ int64_t bdrv_get_dirty_count(BlockDriverState *bs);
void bdrv_enable_copy_on_read(BlockDriverState *bs);
void bdrv_disable_copy_on_read(BlockDriverState *bs);
+void bdrv_ref(BlockDriverState *bs);
+void bdrv_unref(BlockDriverState *bs);
void bdrv_set_in_use(BlockDriverState *bs, int in_use);
int bdrv_in_use(BlockDriverState *bs);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index c6ac871..a282d56 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -294,6 +294,7 @@ struct BlockDriverState {
BlockDeviceIoStatus iostatus;
char device_name[32];
HBitmap *dirty_bitmap;
+ int refcnt;
int in_use; /* users other than guest access, eg. block migration */
QTAILQ_ENTRY(BlockDriverState) list;
--
1.8.3.2
[Qemu-devel] [PATCH 2/8] iscsi: use bdrv_new() instead of stack structure, Fam Zheng, 2013/07/25
[Qemu-devel] [PATCH 4/8] block: make bdrv_delete() static, Fam Zheng, 2013/07/25
[Qemu-devel] [PATCH 5/8] block: use BlockDriverState refcnt for device attach/detach, Fam Zheng, 2013/07/25
[Qemu-devel] [PATCH 6/8] migration: omit drive ref as we have bdrv_ref now, Fam Zheng, 2013/07/25
[Qemu-devel] [PATCH 7/8] xen_disk: simplify blk_disconnect with refcnt, Fam Zheng, 2013/07/25