From patchwork Wed Jul 17 09:42:06 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fam Zheng X-Patchwork-Id: 259660 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 079192C008F for ; Wed, 17 Jul 2013 19:43:20 +1000 (EST) Received: from localhost ([::1]:42679 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UzOGT-0003AC-RO for incoming@patchwork.ozlabs.org; Wed, 17 Jul 2013 05:43:17 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57061) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UzOFv-00033M-6a for qemu-devel@nongnu.org; Wed, 17 Jul 2013 05:42:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UzOFs-0007lm-E7 for qemu-devel@nongnu.org; Wed, 17 Jul 2013 05:42:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55631) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UzOFs-0007la-4k for qemu-devel@nongnu.org; Wed, 17 Jul 2013 05:42:40 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r6H9gdtc006151 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 17 Jul 2013 05:42:39 -0400 Received: from T430s.nay.redhat.com ([10.66.6.13]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id r6H9gVqq026351; Wed, 17 Jul 2013 05:42:36 -0400 From: Fam Zheng To: qemu-devel@nongnu.org Date: Wed, 17 Jul 2013 17:42:06 +0800 Message-Id: <1374054136-28741-2-git-send-email-famz@redhat.com> In-Reply-To: <1374054136-28741-1-git-send-email-famz@redhat.com> References: <1374054136-28741-1-git-send-email-famz@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: kwolf@redhat.com, famz@redhat.com, hbrock@redhat.com, rjones@redhat.com, imain@redhat.com, stefanha@redhat.com, pbonzini@redhat.com Subject: [Qemu-devel] [PATCH v2 01/11] block: replace in_use with refcnt_soft and refcnt_hard X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Introduce refcnt_soft (soft reference) and refcnt_hard (hard reference) to BlockDriverState, since in_use mechanism cannot provide proper management of lifecycle when a BDS is referenced in multiple places (e.g. pointed to by another bs's backing_hd while also used as a block job device, in the use case of image fleecing). The original in_use case is considered a "hard reference" in this patch, where the bs is busy and should not be used in other tasks that require a hard reference. (However the interface doesn't force this, caller still need to call bdrv_in_use() to check by itself.). A soft reference is implemented but not used yet. It will be used in following patches to manage the lifecycle together with hard reference. If bdrv_ref() is called on a BDS, it must be released by exactly the same numbers of bdrv_unref() with the same "soft/hard" type, and never call bdrv_delete() directly. If the BDS is only used locally (unnamed), bdrv_ref/bdrv_unref can be skipped and just use bdrv_delete(). Signed-off-by: Fam Zheng --- block-migration.c | 4 ++-- block.c | 40 +++++++++++++++++++++++++++++++--------- blockjob.c | 6 +++--- hw/block/dataplane/virtio-blk.c | 4 ++-- include/block/block.h | 5 +++-- include/block/block_int.h | 3 ++- 6 files changed, 43 insertions(+), 19 deletions(-) diff --git a/block-migration.c b/block-migration.c index 2fd7699..d558410 100644 --- a/block-migration.c +++ b/block-migration.c @@ -321,7 +321,7 @@ static void init_blk_migration_it(void *opaque, BlockDriverState *bs) bmds->shared_base = block_mig_state.shared_base; alloc_aio_bitmap(bmds); drive_get_ref(drive_get_by_blockdev(bs)); - bdrv_set_in_use(bs, 1); + bdrv_ref(bs, true); block_mig_state.total_sector_sum += sectors; @@ -557,7 +557,7 @@ static void blk_mig_cleanup(void) blk_mig_lock(); while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) { QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry); - bdrv_set_in_use(bmds->bs, 0); + bdrv_unref(bmds->bs, true); drive_put_ref(drive_get_by_blockdev(bmds->bs)); g_free(bmds->aio_bitmap); g_free(bmds); diff --git a/block.c b/block.c index b560241..4170ff6 100644 --- a/block.c +++ b/block.c @@ -1511,8 +1511,11 @@ static void bdrv_move_feature_fields(BlockDriverState *bs_dest, /* dirty bitmap */ bs_dest->dirty_bitmap = bs_src->dirty_bitmap; + /* reference count */ + bs_dest->refcnt_soft = bs_src->refcnt_soft; + bs_dest->refcnt_hard = bs_src->refcnt_hard; + /* job */ - bs_dest->in_use = bs_src->in_use; bs_dest->job = bs_src->job; /* keep the same entry in bdrv_states */ @@ -1542,7 +1545,6 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old) assert(bs_new->dirty_bitmap == NULL); assert(bs_new->job == NULL); assert(bs_new->dev == NULL); - assert(bs_new->in_use == 0); assert(bs_new->io_limits_enabled == false); assert(bs_new->block_timer == NULL); @@ -1561,7 +1563,6 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old) /* Check a few fields that should remain attached to the device */ assert(bs_new->dev == NULL); assert(bs_new->job == NULL); - assert(bs_new->in_use == 0); assert(bs_new->io_limits_enabled == false); assert(bs_new->block_timer == NULL); @@ -1598,7 +1599,6 @@ void bdrv_delete(BlockDriverState *bs) { assert(!bs->dev); assert(!bs->job); - assert(!bs->in_use); /* remove from list, if necessary */ bdrv_make_anon(bs); @@ -4374,15 +4374,37 @@ int64_t bdrv_get_dirty_count(BlockDriverState *bs) } } -void bdrv_set_in_use(BlockDriverState *bs, int in_use) +/* Get a soft or hard reference to bs */ +void bdrv_ref(BlockDriverState *bs, bool is_hard) +{ + if (is_hard) { + bs->refcnt_hard++; + } else { + bs->refcnt_soft++; + } +} + +/* Release a previously grabbed reference to bs, need to specify if it is hard + * or soft. If after this releasing, both soft and hard reference counts are + * zero, the BlockDriverState is deleted. */ +void bdrv_unref(BlockDriverState *bs, bool is_hard) { - assert(bs->in_use != in_use); - bs->in_use = in_use; + if (is_hard) { + assert(bs->refcnt_hard > 0); + bs->refcnt_hard--; + } else { + assert(bs->refcnt_soft > 0); + bs->refcnt_soft--; + } + if (bs->refcnt_hard == 0 && bs->refcnt_soft == 0) { + bdrv_close(bs); + bdrv_delete(bs); + } } -int bdrv_in_use(BlockDriverState *bs) +bool bdrv_in_use(BlockDriverState *bs) { - return bs->in_use; + return bs->refcnt_hard > 0; } void bdrv_iostatus_enable(BlockDriverState *bs) diff --git a/blockjob.c b/blockjob.c index ca80df1..24f07f9 100644 --- a/blockjob.c +++ b/blockjob.c @@ -45,7 +45,7 @@ void *block_job_create(const BlockJobType *job_type, BlockDriverState *bs, error_set(errp, QERR_DEVICE_IN_USE, bdrv_get_device_name(bs)); return NULL; } - bdrv_set_in_use(bs, 1); + bdrv_ref(bs, true); job = g_malloc0(job_type->instance_size); job->job_type = job_type; @@ -63,7 +63,7 @@ void *block_job_create(const BlockJobType *job_type, BlockDriverState *bs, if (error_is_set(&local_err)) { bs->job = NULL; g_free(job); - bdrv_set_in_use(bs, 0); + bdrv_unref(bs, true); error_propagate(errp, local_err); return NULL; } @@ -79,7 +79,7 @@ void block_job_completed(BlockJob *job, int ret) job->cb(job->opaque, ret); bs->job = NULL; g_free(job); - bdrv_set_in_use(bs, 0); + bdrv_unref(bs, true); } void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp) diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index 0356665..3075e84 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -431,7 +431,7 @@ bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk, s->blk = blk; /* Prevent block operations that conflict with data plane thread */ - bdrv_set_in_use(blk->conf.bs, 1); + bdrv_ref(blk->conf.bs, true); error_setg(&s->migration_blocker, "x-data-plane does not support migration"); @@ -450,7 +450,7 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s) virtio_blk_data_plane_stop(s); migrate_del_blocker(s->migration_blocker); error_free(s->migration_blocker); - bdrv_set_in_use(s->blk->conf.bs, 0); + bdrv_unref(s->blk->conf.bs, true); g_free(s); } diff --git a/include/block/block.h b/include/block/block.h index b6b9014..8df8794 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -354,8 +354,9 @@ 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_set_in_use(BlockDriverState *bs, int in_use); -int bdrv_in_use(BlockDriverState *bs); +void bdrv_ref(BlockDriverState *bs, bool is_hard); +void bdrv_unref(BlockDriverState *bs, bool is_hard); +bool bdrv_in_use(BlockDriverState *bs); #ifdef CONFIG_LINUX_AIO int raw_get_aio_fd(BlockDriverState *bs); diff --git a/include/block/block_int.h b/include/block/block_int.h index c6ac871..9de5a8f 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -294,7 +294,8 @@ struct BlockDriverState { BlockDeviceIoStatus iostatus; char device_name[32]; HBitmap *dirty_bitmap; - int in_use; /* users other than guest access, eg. block migration */ + int refcnt_soft; + int refcnt_hard; QTAILQ_ENTRY(BlockDriverState) list; QLIST_HEAD(, BdrvTrackedRequest) tracked_requests;