On Wed, Jun 01, 2011 at 03:24:29AM -0400, Mark Wu wrote: > 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 <[email protected]> > --- > 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 <linux/scatterlist.h> > #include <linux/string_helpers.h> > #include <scsi/scsi_cmnd.h> > +#include <linux/idr.h> > > #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);
As we get index first thing in _probe, let's remove last thing in _remove. I'm not sure violating the rule of cleanup in the reverse order of initialization can lead to problems here, but it's better to stick to this rule regardless, IMO. > -- > 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
