From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40439) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uq4yk-00025T-65 for qemu-devel@nongnu.org; Fri, 21 Jun 2013 13:18:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Uq4yh-00028m-01 for qemu-devel@nongnu.org; Fri, 21 Jun 2013 13:18:30 -0400 Received: from mx.ipv6.kamp.de ([2a02:248:0:51::16]:41063 helo=mx01.kamp.de) by eggs.gnu.org with smtp (Exim 4.71) (envelope-from ) id 1Uq4yg-00028N-Mh for qemu-devel@nongnu.org; Fri, 21 Jun 2013 13:18:26 -0400 Message-ID: <51C48AD2.8000207@kamp.de> Date: Fri, 21 Jun 2013 19:18:10 +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> <51C420C4.6040503@kamp.de> <20130621110707.GF2986@dhcp-200-207.str.redhat.com> <51C47FCD.2030206@redhat.com> <51C48828.6020301@kamp.de> In-Reply-To: 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: ronnie sahlberg Cc: Kevin Wolf , Paolo Bonzini , qemu-devel , Stefan Hajnoczi Am 21.06.2013 19:13, schrieb ronnie sahlberg: > On Fri, Jun 21, 2013 at 10:06 AM, Peter Lieven wrote: >> Am 21.06.2013 18:31, schrieb Paolo Bonzini: >>> Il 21/06/2013 13:07, Kevin Wolf ha scritto: >>>>>>>> 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? >>>>>> Is there a document how to use it? Or can you help here? >>>> The idea would be to take a read lock while any request is in flight >>>> (i.e. qemu_co_rwlock_rdlock() before it's started and >>>> qemu_co_rwlock_unlock() when it completes), and to take a write lock >>>> (qemu_co_rwlock_wrlock) for the part of iscsi_co_is_allocated() that >>>> requires that no other request runs in parallel. >>>> >>> You can just send the SCSI command asynchronously and wait for the >>> result. There is an example in block/qed.c, the same would apply for iscsi. >> thanks for the pointer paolo, this was i was looking for. this here seems to work: >> >> static void >> iscsi_co_is_allocated_cb(struct iscsi_context *iscsi, int status, >> void *command_data, void *opaque) >> { >> struct IscsiTask *iTask = opaque; >> struct scsi_task *task = command_data; >> struct scsi_get_lba_status *lbas = NULL; >> >> iTask->complete = 1; >> >> if (status != 0) { >> error_report("iSCSI: Failed to get_lba_status on iSCSI lun. %s", >> iscsi_get_error(iscsi)); >> iTask->status = 1; >> goto out; >> } >> >> lbas = scsi_datain_unmarshall(task); >> if (lbas == NULL) { >> iTask->status = 1; >> goto out; >> } >> >> memcpy(&iTask->lbasd, &lbas->descriptors[0], >> sizeof(struct scsi_lba_status_descriptor)); > Only the first descriptor? > sector_num -> sector_num+nb_sectors could be partially allocated in > which case you get multiple descriptors. The number of sectors for which the returned provisioning state holds true is set in *pnum. If it is only partly allocated the return value of iscsi_co_is_allocated will be 1 or 0 and pnum returns the number of sectors for which this is true. >> iTask->status = 0; >> >> out: >> scsi_free_scsi_task(task); >> >> if (iTask->co) { >> qemu_coroutine_enter(iTask->co, NULL); >> } >> } >> >> static int coroutine_fn iscsi_co_is_allocated(BlockDriverState *bs, >> int64_t sector_num, >> int nb_sectors, int *pnum) >> { >> IscsiLun *iscsilun = bs->opaque; >> struct IscsiTask iTask; >> int ret; >> >> *pnum = nb_sectors; >> >> if (iscsilun->lbpme == 0) { >> return 1; >> } >> >> iTask.iscsilun = iscsilun; >> iTask.status = 0; >> iTask.complete = 0; >> iTask.bs = bs; >> >> if (iscsi_get_lba_status_task(iscsilun->iscsi, iscsilun->lun, >> sector_qemu2lun(sector_num, iscsilun), >> 8 + 16, iscsi_co_is_allocated_cb, >> &iTask) == NULL) { >> *pnum = 0; >> return 0; >> } >> >> while (!iTask.complete) { >> iscsi_set_events(iscsilun); >> iTask.co = qemu_coroutine_self(); >> qemu_coroutine_yield(); >> } >> >> if (iTask.status != 0) { >> /* in case the get_lba_status_callout fails (i.e. >> * because the device is busy or the cmd is not >> * supported) we pretend all blocks are allocated >> * for backwards compatiblity */ >> return 1; >> } >> >> if (sector_qemu2lun(sector_num, iscsilun) != iTask.lbasd.lba) { >> *pnum = 0; >> return 0; >> } >> >> *pnum = iTask.lbasd.num_blocks * (iscsilun->block_size / BDRV_SECTOR_SIZE); >> if (*pnum > nb_sectors) { >> *pnum = nb_sectors; >> } >> >> return (iTask.lbasd.provisioning == SCSI_PROVISIONING_TYPE_MAPPED) ? 1 : 0; >> >> return ret; >> }