[PATCH v2 4/5] virtiofsd: Specify size of notification buffer using config space

[Vivek Goyal <vgoyal@redhat.com>]

Daemon specifies size of notification buffer needed and that should be done
using config space.

Only ->notify_buf_size value of config space comes from daemon. Rest of
it is filled by qemu device emulation code.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 contrib/virtiofsd/fuse_virtio.c            | 31 ++++++++++++++++++++++
 hw/virtio/vhost-user-fs.c                  | 26 ++++++++++++++++++
 include/hw/virtio/vhost-user-fs.h          |  2 ++
 include/standard-headers/linux/virtio_fs.h |  2 ++
 4 files changed, 61 insertions(+)

diff --git a/contrib/virtiofsd/fuse_virtio.c b/contrib/virtiofsd/fuse_virtio.c
index b1eebcf054..94cf9b3791 100644
--- a/contrib/virtiofsd/fuse_virtio.c
+++ b/contrib/virtiofsd/fuse_virtio.c
@@ -869,6 +869,35 @@ static bool fv_queue_order(VuDev *dev, int qidx)
     return false;
 }
 
+static uint64_t fv_get_protocol_features(VuDev *dev)
+{
+	return 1ull << VHOST_USER_PROTOCOL_F_CONFIG;
+}
+
+static int fv_get_config(VuDev *dev, uint8_t *config, uint32_t len)
+{
+	struct virtio_fs_config fscfg = {};
+	unsigned notify_size, roundto = 64;
+	union fuse_notify_union {
+		struct fuse_notify_poll_wakeup_out	wakeup_out;
+		struct fuse_notify_inval_inode_out	inode_out;
+		struct fuse_notify_inval_entry_out	entry_out;
+		struct fuse_notify_delete_out		delete_out;
+		struct fuse_notify_store_out		store_out;
+		struct fuse_notify_retrieve_out		retrieve_out;
+	};
+
+	notify_size = sizeof(struct fuse_out_header) +
+		      sizeof(union fuse_notify_union);
+	notify_size = ((notify_size + roundto)/roundto) * roundto;
+
+	fscfg.notify_buf_size = notify_size;
+	memcpy(config, &fscfg, len);
+	fuse_log(FUSE_LOG_DEBUG, "%s:Setting notify_buf_size=%d\n", __func__,
+                 fscfg.notify_buf_size);
+	return 0;
+}
+
 static const VuDevIface fv_iface = {
     .get_features = fv_get_features,
     .set_features = fv_set_features,
@@ -877,6 +906,8 @@ static const VuDevIface fv_iface = {
     .queue_set_started = fv_queue_set_started,
 
     .queue_is_processed_in_order = fv_queue_order,
+    .get_protocol_features = fv_get_protocol_features,
+    .get_config = fv_get_config,
 };
 
 /*
diff --git a/hw/virtio/vhost-user-fs.c b/hw/virtio/vhost-user-fs.c
index 5555fe9dbe..5a6d244b98 100644
--- a/hw/virtio/vhost-user-fs.c
+++ b/hw/virtio/vhost-user-fs.c
@@ -277,16 +277,40 @@ uint64_t vhost_user_fs_slave_io(struct vhost_dev *dev, VhostUserFSSlaveMsg *sm,
     return (uint64_t)done;
 }
 
+static int vhost_user_fs_handle_config_change(struct vhost_dev *dev)
+{
+    return 0;
+}
+
+const VhostDevConfigOps fs_ops = {
+    .vhost_dev_config_notifier = vhost_user_fs_handle_config_change,
+};
 
 static void vuf_get_config(VirtIODevice *vdev, uint8_t *config)
 {
     VHostUserFS *fs = VHOST_USER_FS(vdev);
     struct virtio_fs_config fscfg = {};
+    int ret;
+
+    /*
+     * As of now we only get notification buffer size from device. And that's
+     * needed only if notification queue is enabled.
+     */
+    if (fs->notify_enabled) {
+        ret = vhost_dev_get_config(&fs->vhost_dev, (uint8_t *)&fs->fscfg,
+                                   sizeof(struct virtio_fs_config));
+        if (ret < 0) {
+            error_report("vhost-user-fs: get device config space failed."
+                         " ret=%d\n", ret);
+            return;
+        }
+    }
 
     memcpy((char *)fscfg.tag, fs->conf.tag,
            MIN(strlen(fs->conf.tag) + 1, sizeof(fscfg.tag)));
 
     virtio_stl_p(vdev, &fscfg.num_request_queues, fs->conf.num_request_queues);
+    virtio_stl_p(vdev, &fscfg.notify_buf_size, fs->fscfg.notify_buf_size);
 
     memcpy(config, &fscfg, sizeof(fscfg));
 }
@@ -545,6 +569,8 @@ static void vuf_device_realize(DeviceState *dev, Error **errp)
     fs->vhost_dev.nvqs = 2 + fs->conf.num_request_queues;
 
     fs->vhost_dev.vqs = g_new0(struct vhost_virtqueue, fs->vhost_dev.nvqs);
+
+    vhost_dev_set_config_notifier(&fs->vhost_dev, &fs_ops);
     ret = vhost_dev_init(&fs->vhost_dev, &fs->vhost_user,
                          VHOST_BACKEND_TYPE_USER, 0);
     if (ret < 0) {
diff --git a/include/hw/virtio/vhost-user-fs.h b/include/hw/virtio/vhost-user-fs.h
index bd47e0da98..f667cc4b5a 100644
--- a/include/hw/virtio/vhost-user-fs.h
+++ b/include/hw/virtio/vhost-user-fs.h
@@ -14,6 +14,7 @@
 #ifndef _QEMU_VHOST_USER_FS_H
 #define _QEMU_VHOST_USER_FS_H
 
+#include "standard-headers/linux/virtio_fs.h"
 #include "hw/virtio/virtio.h"
 #include "hw/virtio/vhost.h"
 #include "hw/virtio/vhost-user.h"
@@ -58,6 +59,7 @@ typedef struct {
     struct vhost_virtqueue *vhost_vqs;
     struct vhost_dev vhost_dev;
     VhostUserState vhost_user;
+    struct virtio_fs_config fscfg;
 
     /*< public >*/
     MemoryRegion cache;
diff --git a/include/standard-headers/linux/virtio_fs.h b/include/standard-headers/linux/virtio_fs.h
index 9ee95f584f..719216a262 100644
--- a/include/standard-headers/linux/virtio_fs.h
+++ b/include/standard-headers/linux/virtio_fs.h
@@ -17,6 +17,8 @@ struct virtio_fs_config {
 
 	/* Number of request queues */
 	uint32_t num_request_queues;
+	/* Size of notification buffer */
+	uint32_t notify_buf_size;
 } QEMU_PACKED;
 
 #define VIRTIO_FS_PCI_CACHE_BAR 2
-- 
2.20.1