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Tue, 16 Jul 2019 16:11:27 +0000 (UTC) Received: from dresden.str.redhat.com (unknown [10.40.205.58]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C9D9119C68; Tue, 16 Jul 2019 16:11:22 +0000 (UTC) To: John Snow , qemu-block@nongnu.org, qemu-devel@nongnu.org References: <20190716000117.25219-1-jsnow@redhat.com> <20190716000117.25219-10-jsnow@redhat.com> <1e0e9638-6d60-7343-e6db-a1e77b5da932@redhat.com> <4045c084-572a-b274-3acb-f634162e8605@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: <79271f37-fb1e-96d5-ead1-bb7b441fceea@redhat.com> Date: Tue, 16 Jul 2019 18:11:20 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <4045c084-572a-b274-3acb-f634162e8605@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="5vkVQg7ZxFsNNi6sYtcgTsjAFxZerSJZ7" X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Tue, 16 Jul 2019 16:11:27 +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 09/11] block/backup: teach TOP to never copy unallocated regions 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 , vsementsov@virtuozzo.com, Markus Armbruster 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) --5vkVQg7ZxFsNNi6sYtcgTsjAFxZerSJZ7 Content-Type: multipart/mixed; boundary="lDANxdiD0a5YyqSSe4eM0hhVm11AJVwEb"; protected-headers="v1" From: Max Reitz To: John Snow , qemu-block@nongnu.org, qemu-devel@nongnu.org Cc: Eric Blake , Kevin Wolf , vsementsov@virtuozzo.com, Markus Armbruster Message-ID: <79271f37-fb1e-96d5-ead1-bb7b441fceea@redhat.com> Subject: Re: [PATCH v2 09/11] block/backup: teach TOP to never copy unallocated regions References: <20190716000117.25219-1-jsnow@redhat.com> <20190716000117.25219-10-jsnow@redhat.com> <1e0e9638-6d60-7343-e6db-a1e77b5da932@redhat.com> <4045c084-572a-b274-3acb-f634162e8605@redhat.com> In-Reply-To: <4045c084-572a-b274-3acb-f634162e8605@redhat.com> --lDANxdiD0a5YyqSSe4eM0hhVm11AJVwEb Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 16.07.19 18:02, John Snow wrote: >=20 >=20 > On 7/16/19 7:43 AM, Max Reitz wrote: >> On 16.07.19 02:01, John Snow wrote: >>> Presently, If sync=3DTOP is selected, we mark the entire bitmap as di= rty. >>> In the write notifier handler, we dutifully copy out such regions. >>> >>> Fix this in three parts: >>> >>> 1. Mark the bitmap as being initialized before the first yield. >>> 2. After the first yield but before the backup loop, interrogate the >>> allocation status asynchronously and initialize the bitmap. >>> 3. Teach the write notifier to interrogate allocation status if it is= >>> invoked during bitmap initialization. >>> >>> As an effect of this patch, the job progress for TOP backups >>> now behaves like this: >>> >>> - total progress starts at bdrv_length. >>> - As allocation status is interrogated, total progress decreases. >>> - As blocks are copied, current progress increases. >>> >>> Taken together, the floor and ceiling move to meet each other. >>> >>> Signed-off-by: John Snow >>> --- >>> block/backup.c | 78 ++++++++++++++++++++++++++++++++++++++++----= -- >>> block/trace-events | 1 + >>> 2 files changed, 70 insertions(+), 9 deletions(-) >> >> Looks good to me but for a seemingly unrelated change: >> >>> diff --git a/block/backup.c b/block/backup.c >>> index b407d57954..e28fd23f6a 100644 >>> --- a/block/backup.c >>> +++ b/block/backup.c >> >> [...] >> >>> @@ -507,10 +565,12 @@ static int coroutine_fn backup_run(Job *job, Er= ror **errp) >>> * notify callback service CoW requests. */ >>> job_yield(job); >>> } >>> + ret =3D -ECANCELED; >> >> This one. This doesn=E2=80=99t look like it belongs in this patch, an= d I=E2=80=99m not >> even sure it=E2=80=99s correct. Being cancelled is the normal state f= or >> sync=3Dnone, so I suppose it is correct to just return 0 then. >> >> Max >> > Yeah, this is wiggly, so... yes, we can return 0 here. The job > infrastructure machinery is going to change it to an ECANCELED for us > anyway: >=20 > job_completed > job_update_rc > if (!job->ret && job_is_cancelled(job)) { > job->ret =3D -ECANCELED; > } >=20 > So in this case I just figured that I might as well make it explicit; > this is an error exit. >=20 > (I guess just leaving it at 0 means "whatever the job machinery thinks"= > too, which is probably also fine. The job machinery does not distinguis= h > between "canceled and 0" or "canceled and < 0".) Hm, OK. I think it should be an own patch, though. > Since we're here, though... I was wondering if it shouldn't be the case= > that "canceling" a sync=3Dnone job should actually result in success, > unless you force-cancel. OR, allow sync=3Dnone jobs to receive "COMPLET= E" > verbs to finish successfully, or "CANCEL" verbs to terminate with error= =2E That=E2=80=99s what I had thought. (That canceling would be a success.) As for COMPLETE, you want it to emit a READY event right when it=E2=80=99= s started? :-) > (I don't like what mirror does and don't wish to mimic it. I continue t= o > dislike the idea that canceling a ready mirror job allows it to complet= e > with a successful error code.) Hm. Actually, I don=E2=80=99t even care that much. If the user canceled= it, they probably won=E2=80=99t really look at the return code anyway... Max >>> } else { >>> ret =3D backup_loop(s); >>> } >>> =20 >>> + out: >>> notifier_with_return_remove(&s->before_write); >>> =20 >>> /* wait until pending backup_do_cow() calls have completed */ >> --lDANxdiD0a5YyqSSe4eM0hhVm11AJVwEb-- --5vkVQg7ZxFsNNi6sYtcgTsjAFxZerSJZ7 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl0t9ygACgkQ9AfbAGHV z0Dk7gf6AiBkwDoyDjGIthYQ61LnxBpfxmeEjxn4Wkb/CqG4p4XG+1mmXK44gXo3 kj726A2W1rFu0heSPPR8XTm15tGnUjK3cK6nqvHqetNX39gKpBA+iQwEwfMZSiu6 hHVCXPvPLJqNu+r5Uv1jGKPcokxQIdo6Hc27ao+44LrwjJyfmRqLbFoZDkn/CIQZ MQSkn1lKOZ4zJLEGpXr5ujEmu0aXEXa4XBlTeZAXCFw1ko7LYouWmpLLpubuaYIY 8mkO9yrwfoDrC3hiQ2jNREREvIg04gU1XpA7YBY/cgPScIdClDb/vubsP8ECZEL4 re/4Q6GCGMB69Pn0OWr8rkZOVyuMRw== =zpWr -----END PGP SIGNATURE----- --5vkVQg7ZxFsNNi6sYtcgTsjAFxZerSJZ7--