Re: [PATCH 05/16] Add io_uring IO interface

index 293733f61594..9ef9987b4192 100644

--- a/fs/Makefile
+++ b/fs/Makefile

@@ -29,7 +29,7 @@ obj-$(CONFIG_SIGNALFD)		+= signalfd.o
 obj-$(CONFIG_TIMERFD)		+= timerfd.o
 obj-$(CONFIG_EVENTFD)		+= eventfd.o
 obj-$(CONFIG_USERFAULTFD)	+= userfaultfd.o
-obj-$(CONFIG_AIO)               += aio.o
+obj-$(CONFIG_AIO)               += aio.o io_uring.o

diff --git a/fs/io_uring.c b/fs/io_uring.c
new file mode 100644
index 000000000000..ae2b886282bb
--- /dev/null
+++ b/fs/io_uring.c

@@ -0,0 +1,849 @@
+/*
+ * Shared application/kernel submission and completion ring pairs, for
+ * supporting fast/efficient IO.
+ *
+ * Copyright (C) 2019 Jens Axboe
+ */

+struct io_sq_ring {
+	struct io_uring		r;
+	u32			ring_mask;
+	u32			ring_entries;
+	u32			dropped;
+	u32			flags;
+	u32			array[0];
+};

+
+struct io_iocb_ring {
+	struct			io_sq_ring *ring;
+	unsigned		entries;
+	unsigned		ring_mask;
+	struct io_uring_iocb	*iocbs;
+};
+
+struct io_event_ring {
+	struct io_cq_ring	*ring;
+	unsigned		entries;
+	unsigned		ring_mask;
+};

+struct io_ring_ctx {
+	struct percpu_ref	refs;
+
+	unsigned int		flags;
+	unsigned int		max_reqs;

+	struct io_iocb_ring	sq_ring;
+	struct io_event_ring	cq_ring;
+
+	struct work_struct	work;
+
+	struct {
+		struct mutex uring_lock;
+	} ____cacheline_aligned_in_smp;
+
+	struct {
+		struct mutex    ring_lock;
+		wait_queue_head_t wait;
+	} ____cacheline_aligned_in_smp;
+
+	struct {
+		spinlock_t      completion_lock;
+	} ____cacheline_aligned_in_smp;
+};

+struct fsync_iocb {
+	struct work_struct	work;
+	struct file		*file;
+	bool			datasync;
+};

+static const struct file_operations io_scqring_fops;
+
+static void io_ring_ctx_free(struct work_struct *work);
+static void io_ring_ctx_ref_free(struct percpu_ref *ref);

+
+static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
+{
+	struct io_ring_ctx *ctx;
+
+	ctx = kmem_cache_zalloc(ioctx_cachep, GFP_KERNEL);
+	if (!ctx)
+		return NULL;

+{
+	struct io_kiocb *req;
+
+	req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
+	if (!req)
+		return NULL;
+
+	percpu_ref_get(&ctx->refs);
+	req->ki_ctx = ctx;
+	INIT_LIST_HEAD(&req->ki_list);

+static void io_fill_event(struct io_uring_event *ev, struct io_kiocb *kiocb,
+			  long res, unsigned flags)
+{
+	ev->index = kiocb->ki_index;
+	ev->res = res;
+	ev->flags = flags;
+}

+static void io_complete_scqring(struct io_kiocb *iocb, long res, unsigned flags)
+{
+	io_cqring_fill_event(iocb, res, flags);
+	io_complete_iocb(iocb->ki_ctx, iocb);
+}

+	ret = kiocb_set_rw_flags(req, iocb->rw_flags);
+	if (unlikely(ret))
+		goto out_fput;
+
+	/* no one is going to poll for this I/O */
+	req->ki_flags &= ~IOCB_HIPRI;

+static int io_setup_rw(int rw, const struct io_uring_iocb *iocb,
+		       struct iovec **iovec, struct iov_iter *iter)
+{
+	void __user *buf = (void __user *)(uintptr_t)iocb->addr;
+	size_t ret;
+
+	ret = import_single_range(rw, buf, iocb->len, *iovec, iter);
+	*iovec = NULL;
+	return ret;
+}

+		if (S_ISREG(file_inode(file)->i_mode)) {
+			__sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true);
+			__sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
+		}

+static int __io_submit_one(struct io_ring_ctx *ctx,
+			   const struct io_uring_iocb *iocb,
+			   unsigned long ki_index)

+	f = fdget(fd);
+	if (f.file) {
+		struct io_ring_ctx *ctx;

+
+	ctx->sq_ring.iocbs = io_mem_alloc(sizeof(struct io_uring_iocb) *
+						p->sq_entries);

+/*
+ * sys_io_uring_setup:
+ *	Sets up an aio uring context, and returns the fd. Applications asks
+ *	for a ring size, we return the actual sq/cq ring sizes (among other
+ *	things) in the params structure passed in.
+ */

+/*
+ * IO completion data structure
+ */
+struct io_uring_event {
+	__u64	index;		/* what iocb this event came from */
+	__s32	res;		/* result code for this event */
+	__u32	flags;
+};