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, 6 insertions, 28 deletions

diff --git a/net/socket.c b/net/socket.c
index e8892b218708..e1bf93508f05 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -503,21 +503,12 @@ EXPORT_SYMBOL(sock_alloc_file);
 
 static int sock_map_fd(struct socket *sock, int flags)
 {
-	struct file *newfile;
-	int fd = get_unused_fd_flags(flags);
-	if (unlikely(fd < 0)) {
-		sock_release(sock);
-		return fd;
-	}
-
-	newfile = sock_alloc_file(sock, flags, NULL);
-	if (!IS_ERR(newfile)) {
-		fd_install(fd, newfile);
-		return fd;
-	}
+	int fd;
 
-	put_unused_fd(fd);
-	return PTR_ERR(newfile);
+	fd = FD_ADD(flags, sock_alloc_file(sock, flags, NULL));
+	if (fd < 0)
+		sock_release(sock);
+	return fd;
 }
 
 /**
@@ -2012,8 +2003,6 @@ static int __sys_accept4_file(struct file *file, struct sockaddr __user *upeer_s
 			      int __user *upeer_addrlen, int flags)
 {
 	struct proto_accept_arg arg = { };
-	struct file *newfile;
-	int newfd;
 
 	if (flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK))
 		return -EINVAL;
@@ -2021,18 +2010,7 @@ static int __sys_accept4_file(struct file *file, struct sockaddr __user *upeer_s
 	if (SOCK_NONBLOCK != O_NONBLOCK && (flags & SOCK_NONBLOCK))
 		flags = (flags & ~SOCK_NONBLOCK) | O_NONBLOCK;
 
-	newfd = get_unused_fd_flags(flags);
-	if (unlikely(newfd < 0))
-		return newfd;
-
-	newfile = do_accept(file, &arg, upeer_sockaddr, upeer_addrlen,
-			    flags);
-	if (IS_ERR(newfile)) {
-		put_unused_fd(newfd);
-		return PTR_ERR(newfile);
-	}
-	fd_install(newfd, newfile);
-	return newfd;
+	return FD_ADD(flags, do_accept(file, &arg, upeer_sockaddr, upeer_addrlen, flags));
 }
 
 /*