From patchwork Thu May 28 16:36:21 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hannes Reinecke X-Patchwork-Id: 11576283 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 78D2D912 for ; Thu, 28 May 2020 16:36:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 606B4207F5 for ; Thu, 28 May 2020 16:36:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405110AbgE1Qgu (ORCPT ); Thu, 28 May 2020 12:36:50 -0400 Received: from mx2.suse.de ([195.135.220.15]:33208 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405062AbgE1Qgs (ORCPT ); Thu, 28 May 2020 12:36:48 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 52D1BACCC; Thu, 28 May 2020 16:36:46 +0000 (UTC) From: Hannes Reinecke To: "Martin K. Petersen" Cc: Christoph Hellwig , Doug Gilbert , Daniel Wagner , Johannes Thumshirn , James Bottomley , linux-scsi@vger.kernel.org, Hannes Reinecke Subject: [PATCHv3 0/4] scsi: use xarray for devices and targets Date: Thu, 28 May 2020 18:36:21 +0200 Message-Id: <20200528163625.110184-1-hare@suse.de> X-Mailer: git-send-email 2.16.4 Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Hi all, based on the ideas from Doug Gilbert here's now my take on using xarrays for devices and targets. It revolves around two ideas: - The scsi target 'channel' and 'id' numbers are never ever used to the full 32 bit range; channels are well below 10, and no driver is using more than 16 bits for the id. So we can reduce the type of 'channel' and 'id' to 16 bits, and use the 32 bit value 'channel << 16 | id' as the index into the target xarray. - Most SCSI LUNs are below 256 (to ensure compability with older systems). So there we can use the LUN number as the index into the xarray; for larger LUN numbers we'll allocate a separate index. With these changes we can implement an efficient lookup mechanism, devolving into direct lookup for most cases. And iteration should be as efficient as the current, list-based, approach. This patchset now survives basic testing, hence I've removed the 'RFC' tag from the initial patchset. Changes to v1: - Fixup __scsi_iterate_devices() - Include reviews from Johannes - Minor fixes - Include comments from Doug Changes to v2: - Reshuffle hunks as per suggestion from Johannes Hannes Reinecke (4): scsi: convert target lookup to xarray target_core_pscsi: use __scsi_device_lookup() scsi: move target device list to xarray scsi: remove direct device lookup per host drivers/scsi/hosts.c | 3 +- drivers/scsi/scsi.c | 131 ++++++++++++++++++++++++++++--------- drivers/scsi/scsi_lib.c | 9 ++- drivers/scsi/scsi_scan.c | 66 ++++++++----------- drivers/scsi/scsi_sysfs.c | 42 ++++++++---- drivers/target/target_core_pscsi.c | 8 +-- include/scsi/scsi_device.h | 21 +++--- include/scsi/scsi_host.h | 5 +- 8 files changed, 179 insertions(+), 106 deletions(-)