From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37537) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uq4nY-00023d-SV for qemu-devel@nongnu.org; Fri, 21 Jun 2013 13:06:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Uq4nV-0006eZ-VW for qemu-devel@nongnu.org; Fri, 21 Jun 2013 13:06:56 -0400 Received: from mx.ipv6.kamp.de ([2a02:248:0:51::16]:46166 helo=mx01.kamp.de) by eggs.gnu.org with smtp (Exim 4.71) (envelope-from ) id 1Uq4nV-0006eR-Mm for qemu-devel@nongnu.org; Fri, 21 Jun 2013 13:06:53 -0400 Message-ID: <51C48828.6020301@kamp.de> Date: Fri, 21 Jun 2013 19:06:48 +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> In-Reply-To: <51C47FCD.2030206@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 , Stefan Hajnoczi , qemu-devel@nongnu.org, ronniesahlberg@gmail.com 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)); 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; }