[PATCH 1/2] io_uring/register: don't get a reference to the registered ring fd

[Jens Axboe <axboe@kernel.dk>]

This isn't necessary and was only done because the register path isn't a
hot path and hence the extra ref/put doesn't matter, and to have the
exit path be able to unconditionally put whatever file was gotten
regardless of the type.

In preparation for sharing this code with the main io_uring_enter(2)
syscall, drop the reference and have the caller conditionally put the
file if it was a normal file descriptor.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 io_uring/register.c | 8 ++++----
 io_uring/rsrc.c     | 3 ++-
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/io_uring/register.c b/io_uring/register.c
index 35432471a550..95cfa88dc621 100644
--- a/io_uring/register.c
+++ b/io_uring/register.c
@@ -941,7 +941,8 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
 /*
  * Given an 'fd' value, return the ctx associated with if. If 'registered' is
  * true, then the registered index is used. Otherwise, the normal fd table.
- * Caller must call fput() on the returned file, unless it's an ERR_PTR.
+ * Caller must call fput() on the returned file if it isn't a registered file,
+ * unless it's an ERR_PTR.
  */
 struct file *io_uring_register_get_file(unsigned int fd, bool registered)
 {
@@ -958,8 +959,6 @@ struct file *io_uring_register_get_file(unsigned int fd, bool registered)
 			return ERR_PTR(-EINVAL);
 		fd = array_index_nospec(fd, IO_RINGFD_REG_MAX);
 		file = tctx->registered_rings[fd];
-		if (file)
-			get_file(file);
 	} else {
 		file = fget(fd);
 	}
@@ -1038,6 +1037,7 @@ SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
 				ctx->buf_table.nr, ret);
 	mutex_unlock(&ctx->uring_lock);
 
-	fput(file);
+	if (!use_registered_ring)
+		fput(file);
 	return ret;
 }
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 2d8be5edbbf6..cb12194b35e8 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -1291,7 +1291,8 @@ int io_register_clone_buffers(struct io_ring_ctx *ctx, void __user *arg)
 	if (src_ctx != ctx)
 		mutex_unlock(&src_ctx->uring_lock);
 
-	fput(file);
+	if (!registered_src)
+		fput(file);
 	return ret;
 }
 
-- 
2.53.0