[RFC PATCH 3/7] io_uring: support to register bvec buffer to specified io_uring

[Ming Lei <ming.lei@redhat.com>]

Extend io_buffer_register_bvec() and io_buffer_unregister_bvec() for
supporting to register/unregister bvec buffer to specified io_uring,
which FD is usually passed from userspace.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 include/linux/io_uring/cmd.h |  4 ++
 io_uring/rsrc.c              | 83 +++++++++++++++++++++++++++---------
 2 files changed, 67 insertions(+), 20 deletions(-)

diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
index 78fa336a284b..7516fe5cd606 100644
--- a/include/linux/io_uring/cmd.h
+++ b/include/linux/io_uring/cmd.h
@@ -25,6 +25,10 @@ struct io_uring_cmd_data {
 
 struct io_buf_data {
 	unsigned short index;
+	bool has_fd;
+	bool registered_fd;
+
+	int ring_fd;
 	struct request *rq;
 	void (*release)(void *);
 };
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 5f8ab130a573..701dd33fecf7 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -969,21 +969,6 @@ static int __io_buffer_register_bvec(struct io_ring_ctx *ctx,
 	return 0;
 }
 
-int io_buffer_register_bvec(struct io_uring_cmd *cmd,
-			    struct io_buf_data *buf,
-			    unsigned int issue_flags)
-{
-	struct io_ring_ctx *ctx = cmd_to_io_kiocb(cmd)->ctx;
-	int ret;
-
-	io_ring_submit_lock(ctx, issue_flags);
-	ret = __io_buffer_register_bvec(ctx, buf);
-	io_ring_submit_unlock(ctx, issue_flags);
-
-	return ret;
-}
-EXPORT_SYMBOL_GPL(io_buffer_register_bvec);
-
 static int __io_buffer_unregister_bvec(struct io_ring_ctx *ctx,
 				       struct io_buf_data *buf)
 {
@@ -1006,19 +991,77 @@ static int __io_buffer_unregister_bvec(struct io_ring_ctx *ctx,
 	return 0;
 }
 
-int io_buffer_unregister_bvec(struct io_uring_cmd *cmd,
-			      struct io_buf_data *buf,
-			      unsigned int issue_flags)
+static inline int do_reg_unreg_bvec(struct io_ring_ctx *ctx,
+				    struct io_buf_data *buf,
+				    unsigned int issue_flags,
+				    bool reg)
 {
-	struct io_ring_ctx *ctx = cmd_to_io_kiocb(cmd)->ctx;
 	int ret;
 
 	io_ring_submit_lock(ctx, issue_flags);
-	ret = __io_buffer_unregister_bvec(ctx, buf);
+	if (reg)
+		ret = __io_buffer_register_bvec(ctx, buf);
+	else
+		ret = __io_buffer_unregister_bvec(ctx, buf);
 	io_ring_submit_unlock(ctx, issue_flags);
 
 	return ret;
 }
+
+static int io_buffer_reg_unreg_bvec(struct io_ring_ctx *ctx,
+				    struct io_buf_data *buf,
+				    unsigned int issue_flags,
+				    bool reg)
+{
+	struct io_ring_ctx *remote_ctx = ctx;
+	struct file *file = NULL;
+	int ret;
+
+	if (buf->has_fd) {
+		file = io_uring_register_get_file(buf->ring_fd, buf->registered_fd);
+		if (IS_ERR(file))
+			return PTR_ERR(file);
+		remote_ctx = file->private_data;
+		if (!remote_ctx)
+			return -EINVAL;
+	}
+
+	if (remote_ctx == ctx) {
+		do_reg_unreg_bvec(ctx, buf, issue_flags, reg);
+	} else {
+		if (!(issue_flags & IO_URING_F_UNLOCKED))
+			mutex_unlock(&ctx->uring_lock);
+
+		do_reg_unreg_bvec(remote_ctx, buf, IO_URING_F_UNLOCKED, reg);
+
+		if (!(issue_flags & IO_URING_F_UNLOCKED))
+			mutex_lock(&ctx->uring_lock);
+	}
+
+	if (file)
+		fput(file);
+
+	return ret;
+}
+
+int io_buffer_register_bvec(struct io_uring_cmd *cmd,
+			    struct io_buf_data *buf,
+			    unsigned int issue_flags)
+{
+	struct io_ring_ctx *ctx = cmd_to_io_kiocb(cmd)->ctx;
+
+	return io_buffer_reg_unreg_bvec(ctx, buf, issue_flags, true);
+}
+EXPORT_SYMBOL_GPL(io_buffer_register_bvec);
+
+int io_buffer_unregister_bvec(struct io_uring_cmd *cmd,
+			      struct io_buf_data *buf,
+			      unsigned int issue_flags)
+{
+	struct io_ring_ctx *ctx = cmd_to_io_kiocb(cmd)->ctx;
+
+	return io_buffer_reg_unreg_bvec(ctx, buf, issue_flags, false);
+}
 EXPORT_SYMBOL_GPL(io_buffer_unregister_bvec);
 
 static int validate_fixed_range(u64 buf_addr, size_t len,
-- 
2.47.0