Merge tag 'vfs-6.19-rc1.fd_prepare.fs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull fd prepare updates from Christian Brauner:
 "This adds the FD_ADD() and FD_PREPARE() primitive. They simplify the
  common pattern of get_unused_fd_flags() + create file + fd_install()
  that is used extensively throughout the kernel and currently requires
  cumbersome cleanup paths.

  FD_ADD() - For simple cases where a file is installed immediately:

      fd = FD_ADD(O_CLOEXEC, vfio_device_open_file(device));
      if (fd < 0)
          vfio_device_put_registration(device);
      return fd;

  FD_PREPARE() - For cases requiring access to the fd or file, or
  additional work before publishing:

      FD_PREPARE(fdf, O_CLOEXEC, sync_file->file);
      if (fdf.err) {
          fput(sync_file->file);
          return fdf.err;
      }

      data.fence = fd_prepare_fd(fdf);
      if (copy_to_user((void __user *)arg, &data, sizeof(data)))
          return -EFAULT;

      return fd_publish(fdf);

  The primitives are centered around struct fd_prepare. FD_PREPARE()
  encapsulates all allocation and cleanup logic and must be followed by
  a call to fd_publish() which associates the fd with the file and
  installs it into the caller's fdtable. If fd_publish() isn't called,
  both are deallocated automatically. FD_ADD() is a shorthand that does
  fd_publish() immediately and never exposes the struct to the caller.

  I've implemented this in a way that it's compatible with the cleanup
  infrastructure while also being usable separately. IOW, it's centered
  around struct fd_prepare which is aliased to class_fd_prepare_t and so
  we can make use of all the basica guard infrastructure"

* tag 'vfs-6.19-rc1.fd_prepare.fs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (42 commits)
  io_uring: convert io_create_mock_file() to FD_PREPARE()
  file: convert replace_fd() to FD_PREPARE()
  vfio: convert vfio_group_ioctl_get_device_fd() to FD_ADD()
  tty: convert ptm_open_peer() to FD_ADD()
  ntsync: convert ntsync_obj_get_fd() to FD_PREPARE()
  media: convert media_request_alloc() to FD_PREPARE()
  hv: convert mshv_ioctl_create_partition() to FD_ADD()
  gpio: convert linehandle_create() to FD_PREPARE()
  pseries: port papr_rtas_setup_file_interface() to FD_ADD()
  pseries: convert papr_platform_dump_create_handle() to FD_ADD()
  spufs: convert spufs_gang_open() to FD_PREPARE()
  papr-hvpipe: convert papr_hvpipe_dev_create_handle() to FD_PREPARE()
  spufs: convert spufs_context_open() to FD_PREPARE()
  net/socket: convert __sys_accept4_file() to FD_ADD()
  net/socket: convert sock_map_fd() to FD_ADD()
  net/kcm: convert kcm_ioctl() to FD_PREPARE()
  net/handshake: convert handshake_nl_accept_doit() to FD_PREPARE()
  secretmem: convert memfd_secret() to FD_ADD()
  memfd: convert memfd_create() to FD_ADD()
  bpf: convert bpf_token_create() to FD_PREPARE()
  ...

1 files changed, 12 insertions, 22 deletions

diff --git a/drivers/media/mc/mc-request.c b/drivers/media/mc/mc-request.c
index f66f728b1b43..2ac9ac0a740b 100644
--- a/drivers/media/mc/mc-request.c
+++ b/drivers/media/mc/mc-request.c
@@ -282,8 +282,6 @@ EXPORT_SYMBOL_GPL(media_request_get_by_fd);
 int media_request_alloc(struct media_device *mdev, int *alloc_fd)
 {
 	struct media_request *req;
-	struct file *filp;
-	int fd;
 	int ret;
 
 	/* Either both are NULL or both are non-NULL */
@@ -297,19 +295,6 @@ int media_request_alloc(struct media_device *mdev, int *alloc_fd)
 	if (!req)
 		return -ENOMEM;
 
-	fd = get_unused_fd_flags(O_CLOEXEC);
-	if (fd < 0) {
-		ret = fd;
-		goto err_free_req;
-	}
-
-	filp = anon_inode_getfile("request", &request_fops, NULL, O_CLOEXEC);
-	if (IS_ERR(filp)) {
-		ret = PTR_ERR(filp);
-		goto err_put_fd;
-	}
-
-	filp->private_data = req;
 	req->mdev = mdev;
 	req->state = MEDIA_REQUEST_STATE_IDLE;
 	req->num_incomplete_objects = 0;
@@ -320,19 +305,24 @@ int media_request_alloc(struct media_device *mdev, int *alloc_fd)
 	req->updating_count = 0;
 	req->access_count = 0;
 
-	*alloc_fd = fd;
+	FD_PREPARE(fdf, O_CLOEXEC,
+		   anon_inode_getfile("request", &request_fops, NULL,
+				      O_CLOEXEC));
+	if (fdf.err) {
+		ret = fdf.err;
+		goto err_free_req;
+	}
+
+	fd_prepare_file(fdf)->private_data = req;
+
+	*alloc_fd = fd_publish(fdf);
 
 	snprintf(req->debug_str, sizeof(req->debug_str), "%u:%d",
-		 atomic_inc_return(&mdev->request_id), fd);
+		 atomic_inc_return(&mdev->request_id), *alloc_fd);
 	dev_dbg(mdev->dev, "request: allocated %s\n", req->debug_str);
 
-	fd_install(fd, filp);
-
 	return 0;
 
-err_put_fd:
-	put_unused_fd(fd);
-
 err_free_req:
 	if (mdev->ops->req_free)
 		mdev->ops->req_free(req);