From 6c473bbd42becf52b10677500bb509fbfa077140 Mon Sep 17 00:00:00 2001 From: Fam Zheng Date: Fri, 17 Jan 2014 03:07:47 +0100 Subject: [PATCH 04/34] block: implement reference count for BlockDriverState RH-Author: Fam Zheng Message-id: <1389928083-8921-3-git-send-email-famz@redhat.com> Patchwork-id: 56764 O-Subject: [RHEL-7 qemu-kvm PATCH 02/18] block: implement reference count for BlockDriverState Bugzilla: 1041301 RH-Acked-by: Jeffrey Cody RH-Acked-by: Kevin Wolf RH-Acked-by: Stefan Hajnoczi 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 Signed-off-by: Stefan Hajnoczi (cherry picked from commit 9fcb025146676ab376e6159b58f5a5ddb67bf03c) Signed-off-by: Fam Zheng Conflicts: block.c Context conflict because throttling and before_write notifier are not backported yet. Signed-off-by: Fam Zheng --- block.c | 21 +++++++++++++++++++++ include/block/block.h | 2 ++ include/block/block_int.h | 1 + 3 files changed, 24 insertions(+) Signed-off-by: Miroslav Rezanina --- block.c | 21 +++++++++++++++++++++ include/block/block.h | 2 ++ include/block/block_int.h | 1 + 3 files changed, 24 insertions(+), 0 deletions(-) diff --git a/block.c b/block.c index cc7afd4..ddf29d0 100644 --- a/block.c +++ b/block.c @@ -301,6 +301,7 @@ BlockDriverState *bdrv_new(const char *device_name) } bdrv_iostatus_disable(bs); notifier_list_init(&bs->close_notifiers); + bs->refcnt = 1; return bs; } @@ -1580,6 +1581,9 @@ 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; @@ -4754,6 +4758,23 @@ 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); diff --git a/include/block/block.h b/include/block/block.h index e7f718c..a3b7395 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -421,6 +421,8 @@ 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 d49a317..fbfdab7 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -315,6 +315,7 @@ 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; -- 1.7.1