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Tsirkin" To: Christoph Hellwig Cc: Jens Axboe , Jason Wang , Paolo Bonzini , Stefan Hajnoczi , Maxim Levitsky , Alex Dubov , Ulf Hansson , linux-block@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-mmc@vger.kernel.org Subject: Re: [PATCH 2/5] virtio_blk: simplify refcounting Message-ID: <20220203012654-mutt-send-email-mst@kernel.org> References: <20220202155659.107895-1-hch@lst.de> <20220202155659.107895-3-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220202155659.107895-3-hch@lst.de> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, Feb 02, 2022 at 04:56:56PM +0100, Christoph Hellwig wrote: > Implement the ->free_disk method to free the virtio_blk structure only > once the last gendisk reference goes away instead of keeping a local > refcount. > > Signed-off-by: Christoph Hellwig Acked-by: Michael S. Tsirkin > --- > drivers/block/virtio_blk.c | 64 +++++++------------------------------- > 1 file changed, 12 insertions(+), 52 deletions(-) > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > index c443cd64fc9b4..2d939ac1508c1 100644 > --- a/drivers/block/virtio_blk.c > +++ b/drivers/block/virtio_blk.c > @@ -69,13 +69,6 @@ struct virtio_blk { > /* Process context for config space updates */ > struct work_struct config_work; > > - /* > - * Tracks references from block_device_operations open/release and > - * virtio_driver probe/remove so this object can be freed once no > - * longer in use. > - */ > - refcount_t refs; > - > /* What host tells us, plus 2 for header & tailer. */ > unsigned int sg_elems; > > @@ -391,43 +384,6 @@ static int virtblk_get_id(struct gendisk *disk, char *id_str) > return err; > } > > -static void virtblk_get(struct virtio_blk *vblk) > -{ > - refcount_inc(&vblk->refs); > -} > - > -static void virtblk_put(struct virtio_blk *vblk) > -{ > - if (refcount_dec_and_test(&vblk->refs)) { > - ida_simple_remove(&vd_index_ida, vblk->index); > - mutex_destroy(&vblk->vdev_mutex); > - kfree(vblk); > - } > -} > - > -static int virtblk_open(struct block_device *bd, fmode_t mode) > -{ > - struct virtio_blk *vblk = bd->bd_disk->private_data; > - int ret = 0; > - > - mutex_lock(&vblk->vdev_mutex); > - > - if (vblk->vdev) > - virtblk_get(vblk); > - else > - ret = -ENXIO; > - > - mutex_unlock(&vblk->vdev_mutex); > - return ret; > -} > - > -static void virtblk_release(struct gendisk *disk, fmode_t mode) > -{ > - struct virtio_blk *vblk = disk->private_data; > - > - virtblk_put(vblk); > -} > - > /* We provide getgeo only to please some old bootloader/partitioning tools */ > static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) > { > @@ -460,11 +416,19 @@ static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) > return ret; > } > > +static void virtblk_free_disk(struct gendisk *disk) > +{ > + struct virtio_blk *vblk = disk->private_data; > + > + ida_simple_remove(&vd_index_ida, vblk->index); > + mutex_destroy(&vblk->vdev_mutex); > + kfree(vblk); > +} > + > static const struct block_device_operations virtblk_fops = { > - .owner = THIS_MODULE, > - .open = virtblk_open, > - .release = virtblk_release, > - .getgeo = virtblk_getgeo, > + .owner = THIS_MODULE, > + .getgeo = virtblk_getgeo, > + .free_disk = virtblk_free_disk, > }; > > static int index_to_minor(int index) > @@ -791,8 +755,6 @@ static int virtblk_probe(struct virtio_device *vdev) > goto out_free_index; > } > > - /* This reference is dropped in virtblk_remove(). */ > - refcount_set(&vblk->refs, 1); > mutex_init(&vblk->vdev_mutex); > > vblk->vdev = vdev; > @@ -985,8 +947,6 @@ static void virtblk_remove(struct virtio_device *vdev) > kfree(vblk->vqs); > > mutex_unlock(&vblk->vdev_mutex); > - > - virtblk_put(vblk); > } > > #ifdef CONFIG_PM_SLEEP > -- > 2.30.2