From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48337) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YkFDx-00060j-Tx for qemu-devel@nongnu.org; Mon, 20 Apr 2015 13:11:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YkFDu-0006pT-3H for qemu-devel@nongnu.org; Mon, 20 Apr 2015 13:11:09 -0400 Date: Mon, 20 Apr 2015 18:11:00 +0100 From: Stefan Hajnoczi Message-ID: <20150420171100.GB16268@stefanha-thinkpad.redhat.com> References: <1428069921-2957-1-git-send-email-famz@redhat.com> <1428069921-2957-2-git-send-email-famz@redhat.com> <551EA023.8010205@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="yNb1oOkm5a9FJOVX" Content-Disposition: inline In-Reply-To: <551EA023.8010205@redhat.com> Subject: Re: [Qemu-devel] [Qemu-block] [PATCH v2 1/4] blockjob: Allow nested pause List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Stefan Hajnoczi , Fam Zheng , qemu-devel@nongnu.org, qemu-block@nongnu.org --yNb1oOkm5a9FJOVX Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Apr 03, 2015 at 04:13:55PM +0200, Paolo Bonzini wrote: >=20 >=20 > On 03/04/2015 16:05, Fam Zheng wrote: > > This patch changes block_job_pause to increase the pause counter and > > block_job_resume to decrease it. > >=20 > > The counter will allow calling block_job_pause/block_job_resume > > unconditionally on a job when we need to suspend the IO temporarily. > >=20 > > From now on, each block_job_resume must be paired with a block_job_pause > > to keep the counter balanced. > >=20 > > The user pause from QMP or HMP will only trigger block_job_pause once > > until it's resumed, this is achieved by adding a user_paused flag in > > BlockJob. > >=20 > > One occurrence of block_job_resume in mirror_complete is replaced with > > block_job_enter which does what is necessary. > >=20 > > In block_job_cancel, the cancel flag is good enough to instruct > > coroutines to quit loop, so use block_job_enter to replace the unpaired > > block_job_resume. > >=20 > > Upon block job IO error, user is notified about the entering to the > > pause state, so this pause belongs to user pause, set the flag > > accordingly and expect a matching QMP resume. > >=20 > > Signed-off-by: Fam Zheng > > --- > > block/mirror.c | 2 +- > > blockdev.c | 8 +++++--- > > blockjob.c | 23 +++++++++++++++++------ > > include/block/blockjob.h | 20 ++++++++++++++++---- > > 4 files changed, 39 insertions(+), 14 deletions(-) > >=20 > > diff --git a/block/mirror.c b/block/mirror.c > > index 4056164..65b1718 100644 > > --- a/block/mirror.c > > +++ b/block/mirror.c > > @@ -634,7 +634,7 @@ static void mirror_complete(BlockJob *job, Error **= errp) > > } > > =20 > > s->should_complete =3D true; > > - block_job_resume(job); > > + block_job_enter(&s->common); > > } > > =20 > > static const BlockJobDriver mirror_job_driver =3D { > > diff --git a/blockdev.c b/blockdev.c > > index fbb3a79..9132d69 100644 > > --- a/blockdev.c > > +++ b/blockdev.c > > @@ -2699,7 +2699,7 @@ void qmp_block_job_cancel(const char *device, > > force =3D false; > > } > > =20 > > - if (job->paused && !force) { > > + if (job->user_paused && !force) { > > error_setg(errp, "The block job for device '%s' is currently p= aused", > > device); > > goto out; > > @@ -2716,10 +2716,11 @@ void qmp_block_job_pause(const char *device, Er= ror **errp) > > AioContext *aio_context; > > BlockJob *job =3D find_block_job(device, &aio_context, errp); > > =20 > > - if (!job) { > > + if (!job || job->user_paused) { > > return; > > } > > =20 > > + job->user_paused =3D true; > > trace_qmp_block_job_pause(job); > > block_job_pause(job); > > aio_context_release(aio_context); > > @@ -2730,10 +2731,11 @@ void qmp_block_job_resume(const char *device, E= rror **errp) > > AioContext *aio_context; > > BlockJob *job =3D find_block_job(device, &aio_context, errp); > > =20 > > - if (!job) { > > + if (!job || !job->user_paused) { > > return; > > } > > =20 > > + job->user_paused =3D false; > > trace_qmp_block_job_resume(job); > > block_job_resume(job); > > aio_context_release(aio_context); > > diff --git a/blockjob.c b/blockjob.c > > index ba2255d..2755465 100644 > > --- a/blockjob.c > > +++ b/blockjob.c > > @@ -107,7 +107,7 @@ void block_job_set_speed(BlockJob *job, int64_t spe= ed, Error **errp) > > =20 > > void block_job_complete(BlockJob *job, Error **errp) > > { > > - if (job->paused || job->cancelled || !job->driver->complete) { > > + if (job->pause_count || job->cancelled || !job->driver->complete) { > > error_set(errp, QERR_BLOCK_JOB_NOT_READY, > > bdrv_get_device_name(job->bs)); > > return; > > @@ -118,17 +118,26 @@ void block_job_complete(BlockJob *job, Error **er= rp) > > =20 > > void block_job_pause(BlockJob *job) > > { > > - job->paused =3D true; > > + job->pause_count++; > > } > > =20 > > bool block_job_is_paused(BlockJob *job) > > { > > - return job->paused; > > + return job->pause_count > 0; > > } > > =20 > > void block_job_resume(BlockJob *job) > > { > > - job->paused =3D false; > > + assert(job->pause_count > 0); > > + job->pause_count--; > > + if (job->pause_count) { > > + return; > > + } > > + block_job_enter(job); > > +} > > + > > +void block_job_enter(BlockJob *job) > > +{ > > block_job_iostatus_reset(job); > > if (job->co && !job->busy) { > > qemu_coroutine_enter(job->co, NULL); > > @@ -138,7 +147,7 @@ void block_job_resume(BlockJob *job) > > void block_job_cancel(BlockJob *job) > > { > > job->cancelled =3D true; > > - block_job_resume(job); > > + block_job_enter(job); > > } > > =20 > > bool block_job_is_cancelled(BlockJob *job) > > @@ -258,7 +267,7 @@ BlockJobInfo *block_job_query(BlockJob *job) > > info->device =3D g_strdup(bdrv_get_device_name(job->bs)); > > info->len =3D job->len; > > info->busy =3D job->busy; > > - info->paused =3D job->paused; > > + info->paused =3D job->pause_count > 0; > > info->offset =3D job->offset; > > info->speed =3D job->speed; > > info->io_status =3D job->iostatus; > > @@ -335,6 +344,8 @@ BlockErrorAction block_job_error_action(BlockJob *j= ob, BlockDriverState *bs, > > IO_OPERATION_TYPE_WRITE, > > action, &error_abort); > > if (action =3D=3D BLOCK_ERROR_ACTION_STOP) { > > + /* make the pause user visible, which will be resumed from QMP= =2E */ > > + job->user_paused =3D true; > > block_job_pause(job); > > block_job_iostatus_set_err(job, error); > > if (bs !=3D job->bs) { > > diff --git a/include/block/blockjob.h b/include/block/blockjob.h > > index b6d4ebb..9f4b20d 100644 > > --- a/include/block/blockjob.h > > +++ b/include/block/blockjob.h > > @@ -79,10 +79,14 @@ struct BlockJob { > > bool cancelled; > > =20 > > /** > > - * Set to true if the job is either paused, or will pause itself > > - * as soon as possible (if busy =3D=3D true). > > + * Counter for pause request. If non-zero, the block job will paus= e. >=20 > Why not keep the more complete comment ("If non-zero, the block job is > either paused, or if busy =3D=3D true will pause itself as soon as possib= le")? >=20 > > */ > > - bool paused; > > + int pause_count; > > + > > + /** > > + * Set to true if the job is paused by user. >=20 > ... and can be unpaused with the block-job-resume QMP command. I squashed in your suggestions. --yNb1oOkm5a9FJOVX Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJVNTMkAAoJEJykq7OBq3PIt8cH/R3JnlxO1MjHoq2OgC0V8tCa pyXvBvVYVZSAbkxzha/aVKzYCjDSEzQyU3cSHcEUwuSn9NxjfeCWcuWFaSoAmsur 8FDsyFNrbFymaOeduPedS2BUi2zhBfy1RB6dbb7v59oGy1cLUHGOd3KaaM2Kv9qC yKRI8gm96Gidwr1IOTb/HH0RNHJ2bH6/z6q82uQ72cAGiQnNAFvdLuQ2JQ2AQ/pl 5ZNNpa98xA+a8FrbmomRiMcM9YUVsWv9pN8Wv0JgV7WFxpH7GJMDyJtOtsBqNIto qI3ehPRd2WQqwDtacoT6Ntkdx+oRNQrenKTrD8GS3F+6S//VU47ttVvTMX2alY8= =LNfT -----END PGP SIGNATURE----- --yNb1oOkm5a9FJOVX--