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Mon, 2 Sep 2019 14:55:14 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-204-221.brq.redhat.com [10.40.204.221]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 698951001947; Mon, 2 Sep 2019 14:55:13 +0000 (UTC) To: Vladimir Sementsov-Ogievskiy , "qemu-block@nongnu.org" References: <20190809161407.11920-1-mreitz@redhat.com> <20190809161407.11920-28-mreitz@redhat.com> <64a06bc9-ba3a-b666-1d49-e263614d4566@virtuozzo.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: <232f0d57-9c33-e1ef-c6a4-d4be3a4aae13@redhat.com> Date: Mon, 2 Sep 2019 16:55:11 +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: <64a06bc9-ba3a-b666-1d49-e263614d4566@virtuozzo.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="62t3MByb5w85FhdTyQOf5HnonJLQLVoIs" X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.70]); Mon, 02 Sep 2019 14:55:14 +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 27/42] commit: Deal with filters 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) --62t3MByb5w85FhdTyQOf5HnonJLQLVoIs Content-Type: multipart/mixed; boundary="kFjmVcwtqZo6b9vDt2buTmy4PYBNSbIBh"; protected-headers="v1" From: Max Reitz To: Vladimir Sementsov-Ogievskiy , "qemu-block@nongnu.org" Cc: "qemu-devel@nongnu.org" , Kevin Wolf Message-ID: <232f0d57-9c33-e1ef-c6a4-d4be3a4aae13@redhat.com> Subject: Re: [PATCH v6 27/42] commit: Deal with filters References: <20190809161407.11920-1-mreitz@redhat.com> <20190809161407.11920-28-mreitz@redhat.com> <64a06bc9-ba3a-b666-1d49-e263614d4566@virtuozzo.com> In-Reply-To: <64a06bc9-ba3a-b666-1d49-e263614d4566@virtuozzo.com> --kFjmVcwtqZo6b9vDt2buTmy4PYBNSbIBh Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 31.08.19 12:44, Vladimir Sementsov-Ogievskiy wrote: > 09.08.2019 19:13, Max Reitz wrote: >> This includes some permission limiting (for example, we only need to >> take the RESIZE permission if the base is smaller than the top). >> >> Signed-off-by: Max Reitz >> --- >> block/block-backend.c | 16 +++++--- >> block/commit.c | 96 +++++++++++++++++++++++++++++++----------= -- >> blockdev.c | 6 ++- >> 3 files changed, 85 insertions(+), 33 deletions(-) >> >> diff --git a/block/block-backend.c b/block/block-backend.c >> index c13c5c83b0..0bc592d023 100644 >> --- a/block/block-backend.c >> +++ b/block/block-backend.c >> @@ -2180,11 +2180,17 @@ int blk_commit_all(void) >> AioContext *aio_context =3D blk_get_aio_context(blk); >> =20 >> aio_context_acquire(aio_context); >> - if (blk_is_inserted(blk) && blk->root->bs->backing) { >> - int ret =3D bdrv_commit(blk->root->bs); >> - if (ret < 0) { >> - aio_context_release(aio_context); >> - return ret; >> + if (blk_is_inserted(blk)) { >> + BlockDriverState *non_filter; >> + >> + /* Legacy function, so skip implicit filters */ >> + non_filter =3D bdrv_skip_implicit_filters(blk->root->bs);= >> + if (bdrv_filtered_cow_child(non_filter)) { >> + int ret =3D bdrv_commit(non_filter); >> + if (ret < 0) { >> + aio_context_release(aio_context); >> + return ret; >> + } >> } >=20 > and if non_filter is explicit filter we just skip it. I think we'd bett= er return > error in this case. For example, just drop if (bdrv_filtered_cow_child)= and get > ENOTSUP from bdrv_commit in this case. Sounds good, yes. > And with at least this fixed I'm OK with this patch: >=20 > Reviewed-by: Vladimir Sementsov-Ogievskiy >=20 > However some comments below: >=20 >> } >> aio_context_release(aio_context); >> diff --git a/block/commit.c b/block/commit.c >> index 5a7672c7c7..40d1c8eeac 100644 >> --- a/block/commit.c >> +++ b/block/commit.c >> @@ -37,6 +37,7 @@ typedef struct CommitBlockJob { >> BlockBackend *top; >> BlockBackend *base; >> BlockDriverState *base_bs; >> + BlockDriverState *above_base; >=20 > you called it base_overlay in mirror, seems better to keep same naming Indeed. [...] >> @@ -315,17 +336,43 @@ void commit_start(const char *job_id, BlockDrive= rState *bs, >> =20 >> s->commit_top_bs =3D commit_top_bs; >> =20 >> - /* Block all nodes between top and base, because they will >> - * disappear from the chain after this operation. */ >> - assert(bdrv_chain_contains(top, base)); >> - for (iter =3D top; iter !=3D base; iter =3D backing_bs(iter)) { >> - /* XXX BLK_PERM_WRITE needs to be allowed so we don't block o= urselves >> - * at s->base (if writes are blocked for a node, they are als= o blocked >> - * for its backing file). The other options would be a second= filter >> - * driver above s->base. */ >=20 > This code part is absolutely equal to corresponding in block/mirror.c..= It would be great > to put it into a function and reuse. However its not about these series= =2E It would probably be great to just drop block/commit.c altogether and fully merge it into block/mirror.c at some point. (I suppose we=E2=80=99d just have to check whether there=E2=80=99s any pa= rent who=E2=80=99s taken the WRITE permission on the top node, and if so, emit READY (and if not, skip to COMPLETED).) [...] >> @@ -412,19 +457,22 @@ int bdrv_commit(BlockDriverState *bs) >> if (!drv) >> return -ENOMEDIUM; >> =20 >> - if (!bs->backing) { >> + backing_file_bs =3D bdrv_filtered_cow_bs(bs); >=20 > Hmm just note: if in future we'll have cow child which is not bs->backi= ng, a lot of code will > fail, as we always assume that cow child is bs->backing. May be, this s= hould be commented in > bdrv_filtered_cow_child implementation. I couldn=E2=80=99t see why we=E2=80=99d ever do this. I hope we never do= =2E (Aside from just removing bs->file and bs->backing altogether.) 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