From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755053Ab1FHNLH (ORCPT ); Wed, 8 Jun 2011 09:11:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55263 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753334Ab1FHNLG (ORCPT ); Wed, 8 Jun 2011 09:11:06 -0400 Message-ID: <4DEF7521.6030902@redhat.com> Date: Wed, 08 Jun 2011 09:12:01 -0400 From: Mark Wu User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110419 Red Hat/3.1.10-1.el6_0 Lightning/1.0b2 Thunderbird/3.1.10 MIME-Version: 1.0 To: "Michael S. Tsirkin" CC: Rusty Russell , virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] [virt] virtio-blk: Use ida to allocate disk index References: <1306913069-23637-1-git-send-email-dwu@redhat.com> <4DE5F78C.1010102@redhat.com> <20110602103406.GD7943@redhat.com> In-Reply-To: <20110602103406.GD7943@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/02/2011 06:34 AM, Michael S. Tsirkin wrote: > On Wed, Jun 01, 2011 at 04:25:48AM -0400, Mark Wu wrote: >> On 06/01/2011 03:24 AM, Mark Wu wrote: >>> - if (index_to_minor(index)>= 1<< MINORBITS) >>> - return -ENOSPC; >>> + do { >>> + if (!ida_pre_get(&vd_index_ida, GFP_KERNEL)) >>> + return err; >>> + >> There's a problem in above code: err is not initialized before >> using, so change it to return -1; >> + do { >> + if (!ida_pre_get(&vd_index_ida, GFP_KERNEL)) >> + return -1; > > Not -1. Pls return -ENOMEM. > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html Hi Michael, Thanks for pointing out that. This is the revised patch. >>From ffe49efd20938952a09d5a87fe694a6f62937756 Mon Sep 17 00:00:00 2001 From: Mark Wu Date: Wed, 8 Jun 2011 08:25:53 -0400 Subject: [PATCH 1/1] [virt] virtio-blk: Use ida to allocate disk index Current index allocation in virtio-blk is based on a monotonically increasing variable "index". It could cause some confusion about disk name in the case of hot-plugging disks. And it's impossible to find the lowest available index by just maintaining a simple index. So it's changed to use ida to allocate index via referring to the index allocation in scsi disk. Signed-off-by: Mark Wu --- drivers/block/virtio_blk.c | 37 ++++++++++++++++++++++++++++++++----- 1 files changed, 32 insertions(+), 5 deletions(-) diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 079c088..f13b758 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -8,10 +8,14 @@ #include #include #include +#include #define PART_BITS 4 -static int major, index; +static int major; +static DEFINE_SPINLOCK(vd_index_lock); +static DEFINE_IDA(vd_index_ida); + struct workqueue_struct *virtblk_wq; struct virtio_blk @@ -23,6 +27,7 @@ struct virtio_blk /* The disk structure for the kernel. */ struct gendisk *disk; + u32 index; /* Request tracking. */ struct list_head reqs; @@ -343,12 +348,26 @@ static int __devinit virtblk_probe(struct virtio_device *vdev) struct request_queue *q; int err; u64 cap; - u32 v, blk_size, sg_elems, opt_io_size; + u32 v, blk_size, sg_elems, opt_io_size, index; u16 min_io_size; u8 physical_block_exp, alignment_offset; - if (index_to_minor(index) >= 1 << MINORBITS) - return -ENOSPC; + do { + if (!ida_pre_get(&vd_index_ida, GFP_KERNEL)) + return -ENOMEM; + + spin_lock(&vd_index_lock); + err = ida_get_new(&vd_index_ida, &index); + spin_unlock(&vd_index_lock); + } while (err == -EAGAIN); + + if (err) + return err; + + if (index_to_minor(index) >= 1 << MINORBITS) { + err = -ENOSPC; + goto out_free_index; + } /* We need to know how many segments before we allocate. */ err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX, @@ -421,7 +440,7 @@ static int __devinit virtblk_probe(struct virtio_device *vdev) vblk->disk->private_data = vblk; vblk->disk->fops = &virtblk_fops; vblk->disk->driverfs_dev = &vdev->dev; - index++; + vblk->index = index; /* configure queue flush support */ if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) @@ -516,6 +535,10 @@ out_free_vq: vdev->config->del_vqs(vdev); out_free_vblk: kfree(vblk); +out_free_index: + spin_lock(&vd_index_lock); + ida_remove(&vd_index_ida, index); + spin_unlock(&vd_index_lock); out: return err; } @@ -538,6 +561,10 @@ static void __devexit virtblk_remove(struct virtio_device *vdev) mempool_destroy(vblk->pool); vdev->config->del_vqs(vdev); kfree(vblk); + + spin_lock(&vd_index_lock); + ida_remove(&vd_index_ida, vblk->index); + spin_unlock(&vd_index_lock); } static const struct virtio_device_id id_table[] = { -- 1.7.1