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Mon, 12 Aug 2019 12:58:19 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-204-161.brq.redhat.com [10.40.204.161]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D65A618E31; Mon, 12 Aug 2019 12:58:17 +0000 (UTC) To: Vladimir Sementsov-Ogievskiy , "qemu-block@nongnu.org" References: <20190809161407.11920-1-mreitz@redhat.com> <20190809161407.11920-17-mreitz@redhat.com> From: Max Reitz Openpgp: preference=signencrypt Autocrypt: addr=mreitz@redhat.com; prefer-encrypt=mutual; keydata= mQENBFXOJlcBCADEyyhOTsoa/2ujoTRAJj4MKA21dkxxELVj3cuILpLTmtachWj7QW+TVG8U /PsMCFbpwsQR7oEy8eHHZwuGQsNpEtNC2G/L8Yka0BIBzv7dEgrPzIu+W3anZXQW4702+uES U29G8TP/NGfXRRHGlbBIH9KNUnOSUD2vRtpOLXkWsV5CN6vQFYgQfFvmp5ZpPeUe6xNplu8V mcTw8OSEDW/ZnxJc8TekCKZSpdzYoxfzjm7xGmZqB18VFwgJZlIibt1HE0EB4w5GsD7x5ekh awIe3RwoZgZDLQMdOitJ1tUc8aqaxvgA4tz6J6st8D8pS//m1gAoYJWGwwIVj1DjTYLtABEB AAG0HU1heCBSZWl0eiA8bXJlaXR6QHJlZGhhdC5jb20+iQFTBBMBCAA9AhsDBQkSzAMABQsJ CAcCBhUICQoLAgQWAgMBAh4BAheABQJVzie5FRhoa3A6Ly9rZXlzLmdudXBnLm5ldAAKCRD0 B9sAYdXPQDcIB/9uNkbYEex1rHKz3mr12uxYMwLOOFY9fstP5aoVJQ1nWQVB6m2cfKGdcRe1 2/nFaHSNAzT0NnKz2MjhZVmcrpyd2Gp2QyISCfb1FbT82GMtXFj1wiHmPb3CixYmWGQUUh+I AvUqsevLA+WihgBUyaJq/vuDVM1/K9Un+w+Tz5vpeMidlIsTYhcsMhn0L9wlCjoucljvbDy/ 8C9L2DUdgi3XTa0ORKeflUhdL4gucWoAMrKX2nmPjBMKLgU7WLBc8AtV+84b9OWFML6NEyo4 4cP7cM/07VlJK53pqNg5cHtnWwjHcbpGkQvx6RUx6F1My3y52vM24rNUA3+ligVEgPYBuQEN BFXOJlcBCADAmcVUNTWT6yLWQHvxZ0o47KCP8OcLqD+67T0RCe6d0LP8GsWtrJdeDIQk+T+F xO7DolQPS6iQ6Ak2/lJaPX8L0BkEAiMuLCKFU6Bn3lFOkrQeKp3u05wCSV1iKnhg0UPji9V2 W5eNfy8F4ZQHpeGUGy+liGXlxqkeRVhLyevUqfU0WgNqAJpfhHSGpBgihUupmyUg7lfUPeRM DzAN1pIqoFuxnN+BRHdAecpsLcbR8sQddXmDg9BpSKozO/JyBmaS1RlquI8HERQoe6EynJhd 64aICHDfj61rp+/0jTIcevxIIAzW70IadoS/y3DVIkuhncgDBvGbF3aBtjrJVP+5ABEBAAGJ ASUEGAEIAA8FAlXOJlcCGwwFCRLMAwAACgkQ9AfbAGHVz0CbFwf9F/PXxQR9i4N0iipISYjU sxVdjJOM2TMut+ZZcQ6NSMvhZ0ogQxJ+iEQ5OjnIputKvPVd5U7WRh+4lF1lB/NQGrGZQ1ic alkj6ocscQyFwfib+xIe9w8TG1CVGkII7+TbS5pXHRxZH1niaRpoi/hYtgzkuOPp35jJyqT/ /ELbqQTDAWcqtJhzxKLE/ugcOMK520dJDeb6x2xVES+S5LXby0D4juZlvUj+1fwZu+7Io5+B bkhSVPb/QdOVTpnz7zWNyNw+OONo1aBUKkhq2UIByYXgORPFnbfMY7QWHcjpBVw9MgC4tGeF R4bv+1nAMMxKmb5VvQCExr0eFhJUAHAhVg== Message-ID: Date: Mon, 12 Aug 2019 14:58:16 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Skek6HntgcrTx8xDc6edYdB3VUplu5Djf" X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Mon, 12 Aug 2019 12:58:19 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v6 16/42] block: Flush all children in generic code X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , "qemu-devel@nongnu.org" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --Skek6HntgcrTx8xDc6edYdB3VUplu5Djf Content-Type: multipart/mixed; boundary="AxGbxhld7NLAPANVTdAVhAkcTy7TmF21W"; protected-headers="v1" From: Max Reitz To: Vladimir Sementsov-Ogievskiy , "qemu-block@nongnu.org" Cc: "qemu-devel@nongnu.org" , Kevin Wolf Message-ID: Subject: Re: [PATCH v6 16/42] block: Flush all children in generic code References: <20190809161407.11920-1-mreitz@redhat.com> <20190809161407.11920-17-mreitz@redhat.com> In-Reply-To: --AxGbxhld7NLAPANVTdAVhAkcTy7TmF21W Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 10.08.19 17:36, Vladimir Sementsov-Ogievskiy wrote: > 09.08.2019 19:13, Max Reitz wrote: >> If the driver does not support .bdrv_co_flush() so bdrv_co_flush() >> itself has to flush the children of the given node, it should not flus= h >> just bs->file->bs, but in fact all children. >> >> In any case, the BLKDBG_EVENT() should be emitted on the primary child= , >> because that is where a blkdebug node would be if there is any. >> >> Suggested-by: Vladimir Sementsov-Ogievskiy >> Signed-off-by: Max Reitz >> --- >> block/io.c | 23 +++++++++++++++++------ >> 1 file changed, 17 insertions(+), 6 deletions(-) >> >> diff --git a/block/io.c b/block/io.c >> index c5a8e3e6a3..bcc770d336 100644 >> --- a/block/io.c >> +++ b/block/io.c >> @@ -2572,6 +2572,8 @@ static void coroutine_fn bdrv_flush_co_entry(voi= d *opaque) >> =20 >> int coroutine_fn bdrv_co_flush(BlockDriverState *bs) >> { >> + BdrvChild *primary_child =3D bdrv_primary_child(bs); >> + BdrvChild *child; >> int current_gen; >> int ret =3D 0; >> =20 >> @@ -2601,7 +2603,7 @@ int coroutine_fn bdrv_co_flush(BlockDriverState = *bs) >> } >> =20 >> /* Write back cached data to the OS even with cache=3Dunsafe */ >> - BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_OS); >> + BLKDBG_EVENT(primary_child, BLKDBG_FLUSH_TO_OS); >> if (bs->drv->bdrv_co_flush_to_os) { >> ret =3D bs->drv->bdrv_co_flush_to_os(bs); >> if (ret < 0) { >> @@ -2611,15 +2613,15 @@ int coroutine_fn bdrv_co_flush(BlockDriverStat= e *bs) >> =20 >> /* But don't actually force it to the disk with cache=3Dunsafe *= / >> if (bs->open_flags & BDRV_O_NO_FLUSH) { >> - goto flush_parent; >> + goto flush_children; >> } >> =20 >> /* Check if we really need to flush anything */ >> if (bs->flushed_gen =3D=3D current_gen) { >> - goto flush_parent; >> + goto flush_children; >> } >> =20 >> - BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_DISK); >> + BLKDBG_EVENT(primary_child, BLKDBG_FLUSH_TO_DISK); >> if (!bs->drv) { >> /* bs->drv->bdrv_co_flush() might have ejected the BDS >> * (even in case of apparent success) */ >> @@ -2663,8 +2665,17 @@ int coroutine_fn bdrv_co_flush(BlockDriverState= *bs) >> /* Now flush the underlying protocol. It will also have BDRV_O_= NO_FLUSH >> * in the case of cache=3Dunsafe, so there are no useless flushe= s. >> */ >> -flush_parent: >> - ret =3D bs->file ? bdrv_co_flush(bs->file->bs) : 0; >> +flush_children: >> + ret =3D 0; > + QLIST_FOREACH(child, &bs->children, next) { >> + int this_child_ret; >> + >> + this_child_ret =3D bdrv_co_flush(child->bs); >> + if (!ret) { >> + ret =3D this_child_ret; >> + } >> + } >=20 > Hmm, you said that we want to flush only children with write-access fro= m parent.. Good that you remember it, I must have overlooked it (when reading the replies to the previous version). :-) > Shouldn't we check it? Or we assume that it's always safe to call bdrv_= co_flush on > a node? I think it=E2=80=99s always safe. But checking it seems like a nice touc= h, yes. Max >> + >> out: >> /* Notify any pending flushes that we have completed */ >> if (ret =3D=3D 0) { >> >=20 >=20 --AxGbxhld7NLAPANVTdAVhAkcTy7TmF21W-- --Skek6HntgcrTx8xDc6edYdB3VUplu5Djf Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl1RYmgACgkQ9AfbAGHV z0AwBggAhesFsPB2+qEPzFR+8jLfasJUQV2ScQQHYVqPIa3GVz1P4cv35azBrg81 RcwJUnPwKWBHRr8W9OFXN+Btk3jceCq34z0/wmW65nt4jA04RSTKeTdi9hNZApwC 983J67vucz+cQLOoT6nYEAnWnzJdx5HqtijAodPDs+bx7llollcKKR38LmM4K58p Lv6KFsmgKcI83SlSXyLYKHrPkgL+Off5BYIi2u0N9ZSjNMikFG6HievMfI+lP2zf 9k7JUqr8zWz7TH7EAAMIXQLEf3CGDu6cfR+xxG3wiTW4Q7jJNbl4IkrEhyBNO0So 58cacYcGGYbRiwXA14RSWHtzYKJvDg== =HsU9 -----END PGP SIGNATURE----- --Skek6HntgcrTx8xDc6edYdB3VUplu5Djf--