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Wed, 7 Aug 2019 21:27:02 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-204-24.brq.redhat.com [10.40.204.24]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D5E4360852; Wed, 7 Aug 2019 21:27:00 +0000 (UTC) To: Kevin Wolf , qemu-block@nongnu.org References: <20190807144628.4988-1-kwolf@redhat.com> <20190807144628.4988-3-kwolf@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: Wed, 7 Aug 2019 23:26:59 +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: <20190807144628.4988-3-kwolf@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="aixYN0erR78p5ebHFSGeJ4EKRy7QKbg8m" X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Wed, 07 Aug 2019 21:27:03 +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 v2 2/3] mirror: Keep mirror_top_bs drained after dropping permissions 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: qemu-devel@nongnu.org, dplotnikov@virtuozzo.com, vsementsov@virtuozzo.com, den@virtuozzo.com 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) --aixYN0erR78p5ebHFSGeJ4EKRy7QKbg8m Content-Type: multipart/mixed; boundary="X8KNy67oDeSdpoJvIycMQovcW193laVQz"; protected-headers="v1" From: Max Reitz To: Kevin Wolf , qemu-block@nongnu.org Cc: eblake@redhat.com, dplotnikov@virtuozzo.com, vsementsov@virtuozzo.com, den@virtuozzo.com, qemu-devel@nongnu.org Message-ID: Subject: Re: [PATCH v2 2/3] mirror: Keep mirror_top_bs drained after dropping permissions References: <20190807144628.4988-1-kwolf@redhat.com> <20190807144628.4988-3-kwolf@redhat.com> In-Reply-To: <20190807144628.4988-3-kwolf@redhat.com> --X8KNy67oDeSdpoJvIycMQovcW193laVQz Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 07.08.19 16:46, Kevin Wolf wrote: > mirror_top_bs is currently implicitly drained through its connection to= > the source or the target node. However, the drain section for target_bs= > ends early after moving mirror_top_bs from src to target_bs, so that > requests can already be restarted while mirror_top_bs is still present > in the chain, but has dropped all permissions and therefore runs into a= n > assertion failure like this: >=20 > qemu-system-x86_64: block/io.c:1634: bdrv_co_write_req_prepare: > Assertion `child->perm & BLK_PERM_WRITE' failed. >=20 > Keep mirror_top_bs drained until all graph changes have completed. >=20 > Signed-off-by: Kevin Wolf > --- > block/mirror.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) >=20 > diff --git a/block/mirror.c b/block/mirror.c > index 9f5c59ece1..642d6570cc 100644 > --- a/block/mirror.c > +++ b/block/mirror.c > @@ -656,7 +656,10 @@ static int mirror_exit_common(Job *job) > s->target =3D NULL; > =20 > /* We don't access the source any more. Dropping any WRITE/RESIZE = is > - * required before it could become a backing file of target_bs. */= > + * required before it could become a backing file of target_bs. No= t having > + * these permissions any more means that we can't allow any new re= quests on > + * mirror_top_bs from now on, so keep it drained. */ You=E2=80=99re lucky Patchew broke or it would have complained about mult= i-line comments needing /* and */ on separate lines. :-) I=E2=80=99m perfectly happy with this style, though: Reviewed-by: Max Reitz > + bdrv_drained_begin(mirror_top_bs); > bs_opaque->stop =3D true; > bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, > &error_abort); > @@ -724,6 +727,7 @@ static int mirror_exit_common(Job *job) > bs_opaque->job =3D NULL; > =20 > bdrv_drained_end(src); > + bdrv_drained_end(mirror_top_bs); > s->in_drain =3D false; > bdrv_unref(mirror_top_bs); > bdrv_unref(src); >=20 --X8KNy67oDeSdpoJvIycMQovcW193laVQz-- --aixYN0erR78p5ebHFSGeJ4EKRy7QKbg8m Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl1LQiMACgkQ9AfbAGHV z0BH2AgAqB2X647c90rL/EenZNxb7XNzJT/d/MBnTJpbaFfYMo11sMSCfPIH6Chj l/wVX0vxvUN6e4emefuC3f1FSZJD7DUhWfUkunq4xJj6U0ybGIlYse9c/oyU9eKX GNA6yVFxjRDKlOG3vBasdbhlHCapWRR27anJXvhhP7eCMuOEY13n5tMFkNIZr4vC r53ZyWaHOUDpzbjCRouGscm1FKr3EQykzakRpTiNvrH7u+kv7GdVRzMtnUpQvFLB b7gHW3yrv/Rpzj4ELhZMDkmRjnsoNY7LMzIgFAo+WiV8L5+kScck3UnwVphcXJMw 9lXNezWNFr8d1D8cKj19lGhmfOZZpQ== =XT3P -----END PGP SIGNATURE----- --aixYN0erR78p5ebHFSGeJ4EKRy7QKbg8m--