[PATCH 2/2] fuse: virtiofs: Add basic multiqueue support

[Chirantan Ekbote <chirantan@chromium.org>]

Use simple round-robin scheduling based on the `unique` field of the
fuse request to spread requests across multiple queues, if supported by
the device.

Signed-off-by: Chirantan Ekbote <chirantan@chromium.org>
---
 fs/fuse/dev.c       | 4 ----
 fs/fuse/fuse_i.h    | 4 ++++
 fs/fuse/virtio_fs.c | 4 +++-
 3 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 97eec7522bf20..cad9f76c2519c 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -25,10 +25,6 @@
 MODULE_ALIAS_MISCDEV(FUSE_MINOR);
 MODULE_ALIAS("devname:fuse");
 
-/* Ordinary requests have even IDs, while interrupts IDs are odd */
-#define FUSE_INT_REQ_BIT (1ULL << 0)
-#define FUSE_REQ_ID_STEP (1ULL << 1)
-
 static struct kmem_cache *fuse_req_cachep;
 
 static struct fuse_dev *fuse_get_dev(struct file *file)
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index ca344bf714045..110b917d950a8 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -47,6 +47,10 @@
 /** Number of dentries for each connection in the control filesystem */
 #define FUSE_CTL_NUM_DENTRIES 5
 
+/* Ordinary requests have even IDs, while interrupts IDs are odd */
+#define FUSE_INT_REQ_BIT (1ULL << 0)
+#define FUSE_REQ_ID_STEP (1ULL << 1)
+
 /** List of active connections */
 extern struct list_head fuse_conn_list;
 
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index d3c38222a7e4e..c5129fd27930c 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -980,7 +980,7 @@ static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
 static void virtio_fs_wake_pending_and_unlock(struct fuse_iqueue *fiq)
 __releases(fiq->lock)
 {
-	unsigned int queue_id = VQ_REQUEST; /* TODO multiqueue */
+	unsigned int queue_id;
 	struct virtio_fs *fs;
 	struct fuse_req *req;
 	struct virtio_fs_vq *fsvq;
@@ -994,6 +994,8 @@ __releases(fiq->lock)
 	spin_unlock(&fiq->lock);
 
 	fs = fiq->priv;
+	queue_id = ((req->in.h.unique / FUSE_REQ_ID_STEP) %
+		    (uint64_t)fs->num_request_queues) + VQ_REQUEST;
 
 	pr_debug("%s: opcode %u unique %#llx nodeid %#llx in.len %u out.len %u\n",
 		  __func__, req->in.h.opcode, req->in.h.unique,
-- 
2.26.2.303.gf8c07b1a785-goog