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Thu, 16 Jul 2020 15:14:09 +0000 (UTC) Subject: Re: [PATCH v7 20/47] block: Iterate over children in refresh_limits To: Andrey Shinkevich , qemu-block@nongnu.org References: <20200625152215.941773-1-mreitz@redhat.com> <20200625152215.941773-21-mreitz@redhat.com> <9e4dc3da-2c5c-8da5-2d03-c144b9d8b4fd@virtuozzo.com> From: Max Reitz 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: <724d8c58-7a7b-d1ab-4a76-2d79e50fe34f@redhat.com> Date: Thu, 16 Jul 2020 17:14:07 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <9e4dc3da-2c5c-8da5-2d03-c144b9d8b4fd@virtuozzo.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="cG7hBTpKeUZUOMw38tsj2PjcaYhMJaKa8" Received-SPF: pass client-ip=205.139.110.61; envelope-from=mreitz@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/16 09:29:31 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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 , Vladimir Sementsov-Ogievskiy , 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) --cG7hBTpKeUZUOMw38tsj2PjcaYhMJaKa8 Content-Type: multipart/mixed; boundary="3IEiToJUkp5HxLGo139F8irZUS56u7MLA" --3IEiToJUkp5HxLGo139F8irZUS56u7MLA Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 14.07.20 20:37, Andrey Shinkevich wrote: > On 25.06.2020 18:21, Max Reitz wrote: >> Instead of looking at just bs->file and bs->backing, we should look at >> all children that could end up receiving forwarded requests. >> >> Signed-off-by: Max Reitz >> --- >> =C2=A0 block/io.c | 32 ++++++++++++++++---------------- >> =C2=A0 1 file changed, 16 insertions(+), 16 deletions(-) >> >> diff --git a/block/io.c b/block/io.c >> index c2af7711d6..37057f13e0 100644 >> --- a/block/io.c >> +++ b/block/io.c >> @@ -135,6 +135,8 @@ static void bdrv_merge_limits(BlockLimits *dst, >> const BlockLimits *src) >> =C2=A0 void bdrv_refresh_limits(BlockDriverState *bs, Error **errp) >> =C2=A0 { >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 BlockDriver *drv =3D bs->drv; >> +=C2=A0=C2=A0=C2=A0 BdrvChild *c; >> +=C2=A0=C2=A0=C2=A0 bool have_limits; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Error *local_err =3D NULL; >> =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 memset(&bs->bl, 0, sizeof(bs->bl))= ; >> @@ -149,14 +151,21 @@ void bdrv_refresh_limits(BlockDriverState *bs, >> Error **errp) >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 drv->bdrv_co_preadv_par= t) ? 1 : 512; >> =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* Take some limits from the child= ren as a default */ >> -=C2=A0=C2=A0=C2=A0 if (bs->file) { >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 bdrv_refresh_limits(bs->file= ->bs, &local_err); >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (local_err) { >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 erro= r_propagate(errp, local_err); >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 retu= rn; >> +=C2=A0=C2=A0=C2=A0 have_limits =3D false; >> +=C2=A0=C2=A0=C2=A0 QLIST_FOREACH(c, &bs->children, next) { >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (c->role & (BDRV_CHILD_DA= TA | BDRV_CHILD_FILTERED | >> BDRV_CHILD_COW)) >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 { >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 bdrv= _refresh_limits(c->bs, &local_err); >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (= local_err) { >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0 error_propagate(errp, local_err); >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0 return; >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 bdrv= _merge_limits(&bs->bl, &c->bs->bl); >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 have= _limits =3D true; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 bdrv_merge_limits(&bs->bl, &= bs->file->bs->bl); >> -=C2=A0=C2=A0=C2=A0 } else { >> +=C2=A0=C2=A0=C2=A0 } >> + >> +=C2=A0=C2=A0=C2=A0 if (!have_limits) { >=20 >=20 > This conditioned piece of code worked with (bs->file =3D=3D NULL) only. >=20 > Now, it works only if there are neither bs->file, nor bs->backing, nor > else filtered children. >=20 > Is it OK and doesn't break the logic for all cases? Hm. Good question. I think the answer is it=E2=80=99s OK. For DATA and FILTERED, it makes absolute sense to just use their alignments. For COW, maybe not so much? But if there=E2=80=99s a COW chil= d, there has to be a DATA child as well (in practice). So we=E2=80=99ll alway= s consider its alignment, too. (And hypothetically speaking, if there was a COW child but no DATA child, then the only alignment we need to observe is in fact the one of the COW child.) Max --3IEiToJUkp5HxLGo139F8irZUS56u7MLA-- --cG7hBTpKeUZUOMw38tsj2PjcaYhMJaKa8 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl8Qbr8ACgkQ9AfbAGHV z0A0kAf/UYudbfO3cqcdXelYq3vuv6U+YRNa8YcO0iofS4eAPQ3j84rZ7jkaNxR5 F9zAVFqx1zUgkJ0Sv3O0a+Q4YYSXVdFWxHZ6NN++dhT5BwquxVPxXXprVpJOlBie Ql+BzZ0VK6XwPlq7pCxBqGmPwB0vwTtbEWmUWIdNus9maMPRka/9g6uTDwdvM9MP 0MrT13IatHISp70+EyB6K6xsu+JkecwwMVDoo9QFeyk+k0IhcnGUEZeMCIIAKrAS EZmSSjLncxkM0P6TiZQdD5cl++jqbi1MnSIRa/lkm3ApOs0uzgcyidhq8zqlcFhr W25dhjA7uiz1IwpRRri//SUBstDGoQ== =vv4I -----END PGP SIGNATURE----- --cG7hBTpKeUZUOMw38tsj2PjcaYhMJaKa8--