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block: implement reference count for BlockDriverState 

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 <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Fam Zheng 2013-08-23 09:14:46 +08:00 committed by Stefan Hajnoczi
parent 13c91cb7e2
commit 9fcb025146
3 changed files with 24 additions and 0 deletions
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21
block.c
View File

@ -332,6 +332,7 @@ BlockDriverState *bdrv_new(const char *device_name)
notifier_with_return_list_init(&bs->before_write_notifiers);
qemu_co_queue_init(&bs->throttled_reqs[0]);
qemu_co_queue_init(&bs->throttled_reqs[1]);
bs->refcnt = 1;
return bs;
}
@ -1566,6 +1567,9 @@ 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;
@ -4297,6 +4301,23 @@ 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_delete(bs);
}
}
void bdrv_set_in_use(BlockDriverState *bs, int in_use)
{
assert(bs->in_use != in_use);

2
include/block/block.h
View File

@ -355,6 +355,8 @@ 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);

1
include/block/block_int.h
View File

@ -277,6 +277,7 @@ 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;