[PATCH 12/52] virtio_fs: Set up dax_device

Vivek Goyal
2018-12-10T17:12:38Z

From: Stefan Hajnoczi <stefanha@redhat.com>

Setup a dax device.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
fs/fuse/virtio_fs.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 68 insertions(+)

diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 225eb729656f..fd914f2c6209 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -5,6 +5,8 @@
*/

#include <linux/fs.h>
+#include <linux/dax.h>
+#include <linux/pfn_t.h>
#include <linux/module.h>
#include <linux/virtio.h>
#include <linux/virtio_fs.h>
@@ -29,6 +31,11 @@ struct virtio_fs {
struct virtio_fs_vq *vqs;
unsigned nvqs; /* number of virtqueues */
unsigned num_queues; /* number of request queues */
+ struct dax_device *dax_dev;
+
+ /* DAX memory window where file contents are mapped */
+ void *window_kaddr;
+ phys_addr_t window_phys_addr;
};

static inline struct virtio_fs_vq *vq_to_fsvq(struct virtqueue *vq)
@@ -350,6 +357,44 @@ static void virtio_fs_cleanup_vqs(struct virtio_device *vdev,
vdev->config->del_vqs(vdev);
}

+/* Map a window offset to a page frame number. The window offset will have
+ * been produced by .iomap_begin(), which maps a file offset to a window
+ * offset.
+ */
+static long virtio_fs_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
+ long nr_pages, void **kaddr, pfn_t *pfn)
+{
+ struct virtio_fs *fs = dax_get_private(dax_dev);
+ phys_addr_t offset = PFN_PHYS(pgoff);
+
+ if (kaddr)
+ *kaddr = fs->window_kaddr + offset;
+ if (pfn)
+ *pfn = phys_to_pfn_t(fs->window_phys_addr + offset,
+ PFN_DEV | PFN_MAP);
+ return nr_pages;
+}
+
+static size_t virtio_fs_copy_from_iter(struct dax_device *dax_dev,
+ pgoff_t pgoff, void *addr,
+ size_t bytes, struct iov_iter *i)
+{
+ return copy_from_iter(addr, bytes, i);
+}
+
+static size_t virtio_fs_copy_to_iter(struct dax_device *dax_dev,
+ pgoff_t pgoff, void *addr,
+ size_t bytes, struct iov_iter *i)
+{
+ return copy_to_iter(addr, bytes, i);
+}
+
+static const struct dax_operations virtio_fs_dax_ops = {
+ .direct_access = virtio_fs_direct_access,
+ .copy_from_iter = virtio_fs_copy_from_iter,
+ .copy_to_iter = virtio_fs_copy_to_iter,
+};
+
static int virtio_fs_probe(struct virtio_device *vdev)
{
struct virtio_fs *fs;
@@ -371,6 +416,17 @@ static int virtio_fs_probe(struct virtio_device *vdev)
/* TODO vq affinity */
/* TODO populate notifications vq */

+ if (IS_ENABLED(CONFIG_DAX_DRIVER)) {
+ /* TODO map window */
+ fs->window_kaddr = NULL;
+ fs->window_phys_addr = 0;
+
+ fs->dax_dev = alloc_dax(fs, NULL, &virtio_fs_dax_ops);
+ if (!fs->dax_dev)
+ goto out_vqs; /* TODO handle case where device doesn't expose
+ BAR */
+ }
+
/* Bring the device online in case the filesystem is mounted and
* requests need to be sent before we return.
*/
@@ -386,6 +442,12 @@ static int virtio_fs_probe(struct virtio_device *vdev)
vdev->config->reset(vdev);
virtio_fs_cleanup_vqs(vdev, fs);

+ if (fs->dax_dev) {
+ kill_dax(fs->dax_dev);
+ put_dax(fs->dax_dev);
+ fs->dax_dev = NULL;
+ }
+
out:
vdev->priv = NULL;
return ret;
@@ -404,6 +466,12 @@ static void virtio_fs_remove(struct virtio_device *vdev)
list_del(&fs->list);
mutex_unlock(&virtio_fs_mutex);

+ if (fs->dax_dev) {
+ kill_dax(fs->dax_dev);
+ put_dax(fs->dax_dev);
+ fs->dax_dev = NULL;
+ }
+
vdev->priv = NULL;
}

--
2.13.6