From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755306Ab1FAHZH (ORCPT ); Wed, 1 Jun 2011 03:25:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:22343 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753043Ab1FAHZD (ORCPT ); Wed, 1 Jun 2011 03:25:03 -0400 From: Mark Wu To: Rusty Russell , "Michael S. Tsirkin" Cc: virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Mark Wu Subject: [PATCH 1/1] [virt] virtio-blk: Use ida to allocate disk index Date: Wed, 1 Jun 2011 03:24:29 -0400 Message-Id: <1306913069-23637-1-git-send-email-dwu@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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..ba734b3 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 err; + + 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; } @@ -529,6 +552,10 @@ static void __devexit virtblk_remove(struct virtio_device *vdev) /* Nothing should be pending. */ BUG_ON(!list_empty(&vblk->reqs)); + spin_lock(&vd_index_lock); + ida_remove(&vd_index_ida, vblk->index); + spin_unlock(&vd_index_lock); + /* Stop all the virtqueues. */ vdev->config->reset(vdev); -- 1.7.1