[PATCH 17/52] virtio-fs: Retrieve shm capabilities for cache

[Vivek Goyal]

Retrieve the capabilities needed to find the cache.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@xxxxxxxxxx>
---
 fs/fuse/virtio_fs.c            | 15 +++++++++++++++
 include/uapi/linux/virtio_fs.h |  3 +++
 2 files changed, 18 insertions(+)

diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index cd916943205e..60d496c16841 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -520,6 +520,8 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs)
 	phys_addr_t phys_addr;
 	size_t len;
 	int ret;
+	u8 have_cache, cache_bar;
+	u64 cache_offset, cache_len;
 
 	if (!IS_ENABLED(CONFIG_DAX_DRIVER))
 		return 0;
@@ -535,6 +537,19 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs)
 	if (ret < 0)
 		return ret;
 
+	have_cache = virtio_pci_find_shm_cap(pci_dev,
+			VIRTIO_FS_PCI_SHMCAP_ID_CACHE, &cache_bar,
+			&cache_offset, &cache_len);
+
+	if (!have_cache) {
+		dev_err(&vdev->dev, "%s: No cache capability\n",
+			__func__);
+		return -ENXIO;
+	} else {
+		dev_notice(&vdev->dev, "Cache bar: %d len: 0x%llx @ 0x%llx\n",
+				cache_bar, cache_len, cache_offset);
+        }
+
 	/* TODO handle case where device doesn't expose BAR? */
 	ret = pci_request_region(pci_dev, VIRTIO_FS_WINDOW_BAR,
 				 "virtio-fs-window");
diff --git a/include/uapi/linux/virtio_fs.h b/include/uapi/linux/virtio_fs.h
index 48f3590dcfbe..65a9d4a0dac0 100644
--- a/include/uapi/linux/virtio_fs.h
+++ b/include/uapi/linux/virtio_fs.h
@@ -38,4 +38,7 @@ struct virtio_fs_config {
 	__u32 num_queues;
 } __attribute__((packed));
 
+/* For the id field in virtio_pci_shm_cap */
+#define VIRTIO_FS_PCI_SHMCAP_ID_CACHE 0
+
 #endif /* _UAPI_LINUX_VIRTIO_FS_H */
-- 
2.13.6