Cc: "Eugenio Pérez" <eperezma@xxxxxxxxxx>
On Sun, Aug 25, 2024 at 04:07:15PM +0300, Max Gurtovoy wrote:
> Introduce a new helper function virtio_fs_put_locked to encapsulate the
> common pattern of releasing a virtio_fs reference while holding a lock.
> The existing virtio_fs_put helper will be used to release a virtio_fs
> reference while not holding a lock.
>
> Also add an assertion in case the lock is not taken when it should.
>
> Reviewed-by: Idan Zach <izach@xxxxxxxxxx>
> Reviewed-by: Shai Malin <smalin@xxxxxxxxxx>
> Signed-off-by: Max Gurtovoy <mgurtovoy@xxxxxxxxxx>
> ---
> fs/fuse/virtio_fs.c | 17 +++++++++++------
> 1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
> index dd5260141615..43f7be1d7887 100644
> --- a/fs/fuse/virtio_fs.c
> +++ b/fs/fuse/virtio_fs.c
> @@ -201,18 +201,25 @@ static const struct kobj_type virtio_fs_ktype = {
> };
>
> /* Make sure virtiofs_mutex is held */
> -static void virtio_fs_put(struct virtio_fs *fs)
> +static void virtio_fs_put_locked(struct virtio_fs *fs)
> {
> + lockdep_assert_held(&virtio_fs_mutex);
> +
> kobject_put(&fs->kobj);
> }
>
> +static void virtio_fs_put(struct virtio_fs *fs)
> +{
> + mutex_lock(&virtio_fs_mutex);
> + virtio_fs_put_locked(fs);
> + mutex_unlock(&virtio_fs_mutex);
> +}
> +
> static void virtio_fs_fiq_release(struct fuse_iqueue *fiq)
> {
> struct virtio_fs *vfs = fiq->priv;
>
> - mutex_lock(&virtio_fs_mutex);
> virtio_fs_put(vfs);
> - mutex_unlock(&virtio_fs_mutex);
> }
>
> static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq)
> @@ -1052,7 +1059,7 @@ static void virtio_fs_remove(struct virtio_device *vdev)
>
> vdev->priv = NULL;
> /* Put device reference on virtio_fs object */
> - virtio_fs_put(fs);
> + virtio_fs_put_locked(fs);
> mutex_unlock(&virtio_fs_mutex);
> }
>
> @@ -1596,9 +1603,7 @@ static int virtio_fs_get_tree(struct fs_context *fsc)
>
> out_err:
> kfree(fc);
> - mutex_lock(&virtio_fs_mutex);
> virtio_fs_put(fs);
> - mutex_unlock(&virtio_fs_mutex);
> return err;
> }
>
> --
> 2.18.1
