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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190506153429.52737-4-vsementsov@virtuozzo.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="GjOZfBmOnO3EY9jB8Wf8vbzapoT7Ccq3K" X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Tue, 28 May 2019 17:34:15 +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 X-Content-Filtered-By: Mailman/MimeDel 2.1.21 Subject: Re: [Qemu-devel] [PATCH v6 3/3] block/stream: introduce a bottom node X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: fam@euphon.net, kwolf@redhat.com, berto@igalia.com, wencongyang2@huawei.com, xiechanglong.d@gmail.com, stefanha@redhat.com, den@openvz.org, andrey.shinkevich@virtuozzo.com, jsnow@redhat.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) --GjOZfBmOnO3EY9jB8Wf8vbzapoT7Ccq3K From: Max Reitz To: Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org, qemu-block@nongnu.org Cc: xiechanglong.d@gmail.com, wencongyang2@huawei.com, fam@euphon.net, stefanha@redhat.com, kwolf@redhat.com, jsnow@redhat.com, andrey.shinkevich@virtuozzo.com, den@openvz.org, berto@igalia.com Message-ID: Subject: Re: [PATCH v6 3/3] block/stream: introduce a bottom node References: <20190506153429.52737-1-vsementsov@virtuozzo.com> <20190506153429.52737-4-vsementsov@virtuozzo.com> In-Reply-To: <20190506153429.52737-4-vsementsov@virtuozzo.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 06.05.19 17:34, Vladimir Sementsov-Ogievskiy wrote: > From: Andrey Shinkevich >=20 > The bottom node is the intermediate block device that has the base as i= ts > backing image. It is used instead of the base node while a block stream= > job is running to avoid dependency on the base that may change due to t= he > parallel jobs. The change may take place due to a filter node as well t= hat > is inserted between the base and the intermediate bottom node. It occur= s > when the base node is the top one for another commit or stream job. > After the introduction of the bottom node, don't freeze its backing chi= ld, > that's the base, anymore. >=20 > Suggested-by: Vladimir Sementsov-Ogievskiy > Signed-off-by: Andrey Shinkevich > Reviewed-by: Vladimir Sementsov-Ogievskiy > Reviewed-by: Alberto Garcia > --- > block/stream.c | 49 +++++++++++++++++++++---------------------= > tests/qemu-iotests/245 | 4 ++-- > 2 files changed, 27 insertions(+), 26 deletions(-) >=20 > diff --git a/block/stream.c b/block/stream.c > index 65b13b27e0..fc97c89f81 100644 > --- a/block/stream.c > +++ b/block/stream.c [...] > @@ -248,26 +250,25 @@ void stream_start(const char *job_id, BlockDriver= State *bs, > * already have our own plans. Also don't allow resize as the imag= e size is > * queried only at the job start and then cached. */ > s =3D block_job_create(job_id, &stream_job_driver, NULL, bs, > - BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNC= HANGED | > - BLK_PERM_GRAPH_MOD, > - BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNC= HANGED | > - BLK_PERM_WRITE, > + basic_flags | BLK_PERM_GRAPH_MOD, > + basic_flags | BLK_PERM_WRITE, > speed, creation_flags, NULL, NULL, errp); > if (!s) { > goto fail; > } > =20 > - /* Block all intermediate nodes between bs and base, because they = will > - * disappear from the chain after this operation. The streaming jo= b reads > - * every block only once, assuming that it doesn't change, so bloc= k writes > - * and resizes. */ > - for (iter =3D backing_bs(bs); iter && iter !=3D base; iter =3D bac= king_bs(iter)) { > - block_job_add_bdrv(&s->common, "intermediate node", iter, 0, > - BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_U= NCHANGED, > - &error_abort); > + /* > + * Block all intermediate nodes between bs and bottom (inclusive),= because > + * they will disappear from the chain after this operation. The st= reaming > + * job reads every block only once, assuming that it doesn't chang= e, so > + * forbid writes and resizes. > + */ > + for (iter =3D bs; iter !=3D bottom; iter =3D backing_bs(iter)) { > + block_job_add_bdrv(&s->common, "intermediate node", backing_bs= (iter), > + 0, basic_flags, &error_abort); I don=E2=80=99t understand this change. Isn=E2=80=99t it doing exactly t= he same as before? (If so, I just find it harder to read because every iteration isn=E2=80=99= t about @iter but backing_bs(iter).) The rest looks good to me. Max > } > =20 > - s->base =3D base; > + s->bottom =3D bottom; > s->backing_file_str =3D g_strdup(backing_file_str); > s->bs_read_only =3D bs_read_only; > s->chain_frozen =3D true; --GjOZfBmOnO3EY9jB8Wf8vbzapoT7Ccq3K Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAlztcP8ACgkQ9AfbAGHV z0Cc5Qf/UeKAL+BPL+3InGQJWi7B1w9th1IdND1pgmmekuM21XMh+5YtE+av3sW3 ovN/S2y718bXcJKCs20e/vSe7bPw20dHodsHIfNnB7JFRC8qU5l2gbbrff2l4V6e QSiMFKBrImb0YEfuDK3gLp57WFLfVPxxQKOsfk19IFgwiCkXbGu4nfGrd3bv6CGp Dxtk/X0V/panAXqlp1DTbV8CoQnw5ckCOGgrzoQzsI24dQ8cLKZt3dGJ9PyJJ2Ho +npSn00m9Vaw4SGuMdadjMoDytleSfgvx9oGHBJuC+arnarvdOonmUubnIhozsOn 9tfQfznQ6z5spbOYZswTEyTocsTAIA== =zRMW -----END PGP SIGNATURE----- --GjOZfBmOnO3EY9jB8Wf8vbzapoT7Ccq3K--