From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43634) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WDvKr-0001L2-Mb for qemu-devel@nongnu.org; Thu, 13 Feb 2014 07:24:15 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WDvKl-0007UX-KR for qemu-devel@nongnu.org; Thu, 13 Feb 2014 07:24:09 -0500 Received: from paradis.irqsave.net ([62.212.105.220]:49916) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WDvKl-0007UH-33 for qemu-devel@nongnu.org; Thu, 13 Feb 2014 07:24:03 -0500 Date: Thu, 13 Feb 2014 13:24:00 +0100 From: =?iso-8859-1?Q?Beno=EEt?= Canet Message-ID: <20140213122400.GA4547@irqsave.net> References: <1390972061-26560-1-git-send-email-famz@redhat.com> <1390972061-26560-3-git-send-email-famz@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1390972061-26560-3-git-send-email-famz@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v13 02/14] block: Introduce op_blockers to BlockDriverState List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: kwolf@redhat.com, rjones@redhat.com, armbru@redhat.com, qemu-devel@nongnu.org, imain@redhat.com, stefanha@redhat.com, pbonzini@redhat.com The Wednesday 29 Jan 2014 =E0 13:07:29 (+0800), Fam Zheng wrote : > BlockDriverState.op_blockers is an array of lists with BLOCK_OP_TYPE_MA= X > elements. Each list is a list of blockers of an operation type > (BlockOpType), that marks this BDS as currently blocked for a certain > type of operation with reason errors stored in the list. The rule of > usage is: >=20 > * BDS user who wants to take an operation should check if there's any > blocker of the type with bdrv_op_is_blocked(). >=20 > * BDS user who wants to block certain types of operation, should call > bdrv_op_block (or bdrv_op_block_all to block all types of operations= , > which is similar to the existing bdrv_set_in_use()). >=20 > * A blocker is only referenced by op_blockers, so the lifecycle is > managed by caller, and shouldn't be lost until unblock, so typically > a caller does these: >=20 > - Allocate a blocker with error_setg or similar, call bdrv_op_block(= ) > to block some operations. > - Hold the blocker, do his job. > - Unblock operations that it blocked, with the same reason pointer > passed to bdrv_op_unblock(). > - Release the blocker with error_free(). >=20 > Signed-off-by: Fam Zheng > --- > block.c | 71 +++++++++++++++++++++++++++++++++++++++= ++++++++ > include/block/block.h | 7 +++++ > include/block/block_int.h | 5 ++++ > 3 files changed, 83 insertions(+) >=20 > diff --git a/block.c b/block.c > index cb21a5f..967de98 100644 > --- a/block.c > +++ b/block.c > @@ -1838,6 +1838,8 @@ static void bdrv_move_feature_fields(BlockDriverS= tate *bs_dest, > * We do want to swap name but don't want to swap linked list entr= ies > */ > bs_dest->node_list =3D bs_src->node_list; > + memcpy(bs_dest->op_blockers, bs_src->op_blockers, > + sizeof(bs_dest->op_blockers)); > } > =20 > /* > @@ -5119,6 +5121,75 @@ void bdrv_unref(BlockDriverState *bs) > } > } > =20 > +struct BdrvOpBlocker { > + Error *reason; > + QLIST_ENTRY(BdrvOpBlocker) list; > +}; > + > +bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **= errp) > +{ > + BdrvOpBlocker *blocker; > + assert((int) op >=3D 0 && op < BLOCK_OP_TYPE_MAX); > + if (!QLIST_EMPTY(&bs->op_blockers[op])) { > + blocker =3D QLIST_FIRST(&bs->op_blockers[op]); > + if (errp) { > + *errp =3D error_copy(blocker->reason); When an operation is blocked the first reason found is returned as **errp= . I think that this could lead to some randomization of the error messages depending on the bdrv_op_block call order. > + } > + return true; > + } > + return false; > +} > + > +void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason= ) > +{ > + BdrvOpBlocker *blocker; > + assert((int) op >=3D 0 && op < BLOCK_OP_TYPE_MAX); > + > + blocker =3D g_malloc0(sizeof(BdrvOpBlocker)); > + blocker->reason =3D reason; > + QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list); > +} > + > +void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reas= on) > +{ > + BdrvOpBlocker *blocker, *next; > + assert((int) op >=3D 0 && op < BLOCK_OP_TYPE_MAX); > + QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) { > + if (blocker->reason =3D=3D reason) { > + QLIST_REMOVE(blocker, list); > + g_free(blocker); > + } > + } > +} > + > +void bdrv_op_block_all(BlockDriverState *bs, Error *reason) > +{ > + int i; > + for (i =3D 0; i < BLOCK_OP_TYPE_MAX; i++) { > + bdrv_op_block(bs, i, reason); > + } > +} > + > +void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason) > +{ > + int i; > + for (i =3D 0; i < BLOCK_OP_TYPE_MAX; i++) { > + bdrv_op_unblock(bs, i, reason); > + } > +} > + > +bool bdrv_op_blocker_is_empty(BlockDriverState *bs) > +{ > + int i; > + > + for (i =3D 0; i < BLOCK_OP_TYPE_MAX; i++) { > + if (!QLIST_EMPTY(&bs->op_blockers[i])) { > + return false; > + } > + } > + return true; > +} > + > void bdrv_set_in_use(BlockDriverState *bs, int in_use) > { > assert(bs->in_use !=3D in_use); > diff --git a/include/block/block.h b/include/block/block.h > index 9626650..f4a70c9 100644 > --- a/include/block/block.h > +++ b/include/block/block.h > @@ -473,6 +473,13 @@ void bdrv_unref(BlockDriverState *bs); > void bdrv_set_in_use(BlockDriverState *bs, int in_use); > int bdrv_in_use(BlockDriverState *bs); > =20 > +bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **= errp); > +void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason= ); > +void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reas= on); > +void bdrv_op_block_all(BlockDriverState *bs, Error *reason); > +void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason); > +bool bdrv_op_blocker_is_empty(BlockDriverState *bs); > + > #ifdef CONFIG_LINUX_AIO > int raw_get_aio_fd(BlockDriverState *bs); > #else > diff --git a/include/block/block_int.h b/include/block/block_int.h > index 0bcf1c9..4e558d0 100644 > --- a/include/block/block_int.h > +++ b/include/block/block_int.h > @@ -270,6 +270,8 @@ typedef struct BlockLimits { > size_t opt_mem_alignment; > } BlockLimits; > =20 > +typedef struct BdrvOpBlocker BdrvOpBlocker; > + > /* > * Note: the function bdrv_append() copies and swaps contents of > * BlockDriverStates, so if you add new fields to this struct, please > @@ -361,6 +363,9 @@ struct BlockDriverState { > =20 > QLIST_HEAD(, BdrvTrackedRequest) tracked_requests; > =20 > + /* operation blockers */ > + QLIST_HEAD(, BdrvOpBlocker) op_blockers[BLOCK_OP_TYPE_MAX]; > + > /* long-running background operation */ > BlockJob *job; > =20 > --=20 > 1.8.5.3 >=20 >=20