From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35000) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ur9cS-00056d-QT for qemu-devel@nongnu.org; Mon, 24 Jun 2013 12:27:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ur9WF-0006FA-F6 for qemu-devel@nongnu.org; Mon, 24 Jun 2013 12:21:38 -0400 Received: from mx.ipv6.kamp.de ([2a02:248:0:51::16]:60269 helo=mx01.kamp.de) by eggs.gnu.org with smtp (Exim 4.71) (envelope-from ) id 1Ur9MU-0001lI-Ry for qemu-devel@nongnu.org; Mon, 24 Jun 2013 12:11:27 -0400 Message-ID: <51C86FAC.9070303@kamp.de> Date: Mon, 24 Jun 2013 18:11:24 +0200 From: Peter Lieven MIME-Version: 1.0 References: <1371752409-16313-1-git-send-email-pl@kamp.de> <1371752409-16313-2-git-send-email-pl@kamp.de> <20130621091842.GB2986@dhcp-200-207.str.redhat.com> <20130624081343.GE8700@stefanha-thinkpad.redhat.com> <51C84E61.3000600@redhat.com> In-Reply-To: <51C84E61.3000600@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 1/2] iscsi: add support for bdrv_co_is_allocated() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Kevin Wolf , ronniesahlberg@gmail.com, qemu-devel@nongnu.org, Stefan Hajnoczi Am 24.06.2013 15:49, schrieb Paolo Bonzini: > Il 24/06/2013 10:13, Stefan Hajnoczi ha scritto: >> On Fri, Jun 21, 2013 at 11:18:42AM +0200, Kevin Wolf wrote: >>> Am 20.06.2013 um 20:20 hat Peter Lieven geschrieben: >>>> @@ -800,6 +801,60 @@ iscsi_getlength(BlockDriverState *bs) >>>> return len; >>>> } >>>> >>>> +static int coroutine_fn iscsi_co_is_allocated(BlockDriverState *bs, >>>> + int64_t sector_num, >>>> + int nb_sectors, int *pnum) >>>> +{ >>>> + IscsiLun *iscsilun = bs->opaque; >>>> + struct scsi_task *task = NULL; >>>> + struct scsi_get_lba_status *lbas = NULL; >>>> + struct scsi_lba_status_descriptor *lbasd = NULL; >>>> + int ret; >>>> + >>>> + *pnum = nb_sectors; >>>> + >>>> + if (iscsilun->lbpme == 0) { >>>> + return 1; >>>> + } >>>> + >>>> + /* in-flight requests could invalidate the lba status result */ >>>> + while (iscsi_process_flush(iscsilun)) { >>>> + qemu_aio_wait(); >>>> + } >>> Note that you're blocking here. The preferred way would be something >>> involving a yield from the coroutine and a reenter as soon as all >>> requests are done. Maybe a CoRwLock does what you need? >> The other option is to avoid synchronization here and instead process >> bs->tracked_requests so that any in-flight writes count as allocated. > I think it's a bug if the caller doesn't take into account in-flight > requests. For example mirroring expects writes to mark sectors as > dirty, which will pick up everything that is_allocated fails to pick up. > > If all else fails, you can always add a bdrv_drain_all before the query. > > Hence, this check is not needed. In fact, raw-posix does not perform it. > > Paolo Please ignore this patch and look at the async version in the series which also contained the write zero optimizations. thanks, Peter