From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: [PATCH 2/2] scsi_transport_fc: Implement 'async_user_scan' module parameter Date: Mon, 22 Feb 2016 08:51:02 +0100 Message-ID: <1456127462-2817-3-git-send-email-hare@suse.de> References: <1456127462-2817-1-git-send-email-hare@suse.de> Return-path: Received: from mx2.suse.de ([195.135.220.15]:49217 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753720AbcBVHvV (ORCPT ); Mon, 22 Feb 2016 02:51:21 -0500 In-Reply-To: <1456127462-2817-1-git-send-email-hare@suse.de> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: "Martin K . Petersen" Cc: Christoph Hellwig , James Bottomley , Johannes Thumshirn , linux-scsi@vger.kernel.org, Hannes Reinecke When invoking a scan via the sysfs 'scan' attribute the process will be blocked until the scan is completed, which can take a very long time on large installations. Enabling the 'async_user_scan' parameter moves the actual LUN scanning to a workqueue, thereby unblocking the process. Signed-off-by: Hannes Reinecke --- drivers/scsi/scsi_transport_fc.c | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c index 90228b4..3afe60a9 100644 --- a/drivers/scsi/scsi_transport_fc.c +++ b/drivers/scsi/scsi_transport_fc.c @@ -82,6 +82,21 @@ MODULE_PARM_DESC(disable_target_scan, "Disable target scan on remote ports (default=0)"); /* + * async_user_scan: make 'scan' sysfs attribute asynchronous + * on larger installations scanning can take a very long time + * during which the process invoking the scan will be blocked + * on writing to the 'scan' attribute. Enabling this attribute + * will move scanning to a work queue, allowing the process + * to return immediately. + */ +static bool fc_async_user_scan; + +module_param_named(async_user_scan, fc_async_user_scan, + bool, S_IRUGO|S_IWUSR); +MODULE_PARM_DESC(async_user_scan, + "Allow for asynchronous user LUN scanning (default=0)"); + +/* * Redefine so that we can have same named attributes in the * sdev/starget/host objects. */ @@ -2121,8 +2136,18 @@ fc_user_scan_tgt(struct Scsi_Host *shost, uint channel, uint id, u64 lun) if ((channel == rport->channel) && (id == rport->scsi_target_id)) { - spin_unlock_irqrestore(shost->host_lock, flags); - scsi_scan_target(&rport->dev, channel, id, lun, 1); + if (lun == SCAN_WILD_CARD && + fc_async_user_scan) { + if (!(rport->flags & FC_RPORT_SCAN_PENDING)) { + rport->flags |= FC_RPORT_SCAN_PENDING; + scsi_queue_work(shost, + &rport->scan_work); + } + spin_unlock_irqrestore(shost->host_lock, flags); + } else { + spin_unlock_irqrestore(shost->host_lock, flags); + scsi_scan_target(&rport->dev, channel, id, lun, 1); + } return; } } -- 2.6.2