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()
  ...

15 files changed, 173 insertions, 366 deletions

diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index 180a458fc4f7..b8381c7fb636 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -280,27 +280,8 @@ static int __anon_inode_getfd(const char *name,
 			      const struct inode *context_inode,
 			      bool make_inode)
 {
-	int error, fd;
-	struct file *file;
-
-	error = get_unused_fd_flags(flags);
-	if (error < 0)
-		return error;
-	fd = error;
-
-	file = __anon_inode_getfile(name, fops, priv, flags, context_inode,
-				    make_inode);
-	if (IS_ERR(file)) {
-		error = PTR_ERR(file);
-		goto err_put_unused_fd;
-	}
-	fd_install(fd, file);
-
-	return fd;
-
-err_put_unused_fd:
-	put_unused_fd(fd);
-	return error;
+	return FD_ADD(flags, __anon_inode_getfile(name, fops, priv, flags,
+						  context_inode, make_inode));
 }
 
 /**
diff --git a/fs/autofs/dev-ioctl.c b/fs/autofs/dev-ioctl.c
index ed2efe4e97b2..a58f9248b0f5 100644
--- a/fs/autofs/dev-ioctl.c
+++ b/fs/autofs/dev-ioctl.c
@@ -231,32 +231,14 @@ static int test_by_type(const struct path *path, void *p)
  */
 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 {
-	int err, fd;
-
-	fd = get_unused_fd_flags(O_CLOEXEC);
-	if (likely(fd >= 0)) {
-		struct file *filp;
-		struct path path;
-
-		err = find_autofs_mount(name, &path, test_by_dev, &devid);
-		if (err)
-			goto out;
-
-		filp = dentry_open(&path, O_RDONLY, current_cred());
-		path_put(&path);
-		if (IS_ERR(filp)) {
-			err = PTR_ERR(filp);
-			goto out;
-		}
-
-		fd_install(fd, filp);
-	}
+	struct path path __free(path_put) = {};
+	int err;
 
-	return fd;
+	err = find_autofs_mount(name, &path, test_by_dev, &devid);
+	if (err)
+		return err;
 
-out:
-	put_unused_fd(fd);
-	return err;
+	return FD_ADD(O_CLOEXEC, dentry_open(&path, O_RDONLY, current_cred()));
 }
 
 /* Open a file descriptor on an autofs mount point */
diff --git a/fs/eventfd.c b/fs/eventfd.c
index af42b2c7d235..3219e0d596fe 100644
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -378,9 +378,7 @@ EXPORT_SYMBOL_GPL(eventfd_ctx_fileget);
 
 static int do_eventfd(unsigned int count, int flags)
 {
-	struct eventfd_ctx *ctx;
-	struct file *file;
-	int fd;
+	struct eventfd_ctx *ctx __free(kfree) = NULL;
 
 	/* Check the EFD_* constants for consistency.  */
 	BUILD_BUG_ON(EFD_CLOEXEC != O_CLOEXEC);
@@ -398,26 +396,19 @@ static int do_eventfd(unsigned int count, int flags)
 	init_waitqueue_head(&ctx->wqh);
 	ctx->count = count;
 	ctx->flags = flags;
-	ctx->id = ida_alloc(&eventfd_ida, GFP_KERNEL);
 
 	flags &= EFD_SHARED_FCNTL_FLAGS;
 	flags |= O_RDWR;
-	fd = get_unused_fd_flags(flags);
-	if (fd < 0)
-		goto err;
-
-	file = anon_inode_getfile_fmode("[eventfd]", &eventfd_fops,
-					ctx, flags, FMODE_NOWAIT);
-	if (IS_ERR(file)) {
-		put_unused_fd(fd);
-		fd = PTR_ERR(file);
-		goto err;
-	}
-	fd_install(fd, file);
-	return fd;
-err:
-	eventfd_free_ctx(ctx);
-	return fd;
+
+	FD_PREPARE(fdf, flags,
+		   anon_inode_getfile_fmode("[eventfd]", &eventfd_fops, ctx,
+					    flags, FMODE_NOWAIT));
+	if (fdf.err)
+		return fdf.err;
+
+	ctx->id = ida_alloc(&eventfd_ida, GFP_KERNEL);
+	retain_and_null_ptr(ctx);
+	return fd_publish(fdf);
 }
 
 SYSCALL_DEFINE2(eventfd2, unsigned int, count, int, flags)
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index ee7c4b683ec3..6c36d9dc6926 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -2165,9 +2165,8 @@ static void clear_tfile_check_list(void)
  */
 static int do_epoll_create(int flags)
 {
-	int error, fd;
-	struct eventpoll *ep = NULL;
-	struct file *file;
+	int error;
+	struct eventpoll *ep;
 
 	/* Check the EPOLL_* constant for consistency.  */
 	BUILD_BUG_ON(EPOLL_CLOEXEC != O_CLOEXEC);
@@ -2184,26 +2183,15 @@ static int do_epoll_create(int flags)
 	 * Creates all the items needed to setup an eventpoll file. That is,
 	 * a file structure and a free file descriptor.
 	 */
-	fd = get_unused_fd_flags(O_RDWR | (flags & O_CLOEXEC));
-	if (fd < 0) {
-		error = fd;
-		goto out_free_ep;
-	}
-	file = anon_inode_getfile("[eventpoll]", &eventpoll_fops, ep,
-				 O_RDWR | (flags & O_CLOEXEC));
-	if (IS_ERR(file)) {
-		error = PTR_ERR(file);
-		goto out_free_fd;
+	FD_PREPARE(fdf, O_RDWR | (flags & O_CLOEXEC),
+		   anon_inode_getfile("[eventpoll]", &eventpoll_fops, ep,
+				      O_RDWR | (flags & O_CLOEXEC)));
+	if (fdf.err) {
+		ep_clear_and_put(ep);
+		return fdf.err;
 	}
-	ep->file = file;
-	fd_install(fd, file);
-	return fd;
-
-out_free_fd:
-	put_unused_fd(fd);
-out_free_ep:
-	ep_clear_and_put(ep);
-	return error;
+	ep->file = fd_prepare_file(fdf);
+	return fd_publish(fdf);
 }
 
 SYSCALL_DEFINE1(epoll_create1, int, flags)
diff --git a/fs/exec.c b/fs/exec.c
index 4298e7e08d5d..7cb001a222d1 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1280,10 +1280,9 @@ int begin_new_exec(struct linux_binprm * bprm)
 
 	/* Pass the opened binary to the interpreter. */
 	if (bprm->have_execfd) {
-		retval = get_unused_fd_flags(0);
+		retval = FD_ADD(0, bprm->executable);
 		if (retval < 0)
 			goto out_unlock;
-		fd_install(retval, bprm->executable);
 		bprm->executable = NULL;
 		bprm->execfd = retval;
 	}
diff --git a/fs/fhandle.c b/fs/fhandle.c
index 052f9c9368fb..3de1547ec9d4 100644
--- a/fs/fhandle.c
+++ b/fs/fhandle.c
@@ -404,32 +404,28 @@ out_path:
 	return retval;
 }
 
+static struct file *file_open_handle(struct path *path, int open_flag)
+{
+	const struct export_operations *eops;
+
+	eops = path->mnt->mnt_sb->s_export_op;
+	if (eops->open)
+		return eops->open(path, open_flag);
+
+	return file_open_root(path, "", open_flag, 0);
+}
+
 static long do_handle_open(int mountdirfd, struct file_handle __user *ufh,
 			   int open_flag)
 {
-	long retval = 0;
+	long retval;
 	struct path path __free(path_put) = {};
-	struct file *file;
-	const struct export_operations *eops;
 
 	retval = handle_to_path(mountdirfd, ufh, &path, open_flag);
 	if (retval)
 		return retval;
 
-	CLASS(get_unused_fd, fd)(open_flag);
-	if (fd < 0)
-		return fd;
-
-	eops = path.mnt->mnt_sb->s_export_op;
-	if (eops->open)
-		file = eops->open(&path, open_flag);
-	else
-		file = file_open_root(&path, "", open_flag, 0);
-	if (IS_ERR(file))
-		return PTR_ERR(file);
-
-	fd_install(fd, file);
-	return take_fd(fd);
+	return FD_ADD(open_flag, file_open_handle(&path, open_flag));
 }
 
 /**
diff --git a/fs/file.c b/fs/file.c
index 3f56890068aa..0a4f3bdb2dec 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -1380,28 +1380,25 @@ out_unlock:
  */
 int receive_fd(struct file *file, int __user *ufd, unsigned int o_flags)
 {
-	int new_fd;
 	int error;
 
 	error = security_file_receive(file);
 	if (error)
 		return error;
 
-	new_fd = get_unused_fd_flags(o_flags);
-	if (new_fd < 0)
-		return new_fd;
+	FD_PREPARE(fdf, o_flags, file);
+	if (fdf.err)
+		return fdf.err;
+	get_file(file);
 
 	if (ufd) {
-		error = put_user(new_fd, ufd);
-		if (error) {
-			put_unused_fd(new_fd);
+		error = put_user(fd_prepare_fd(fdf), ufd);
+		if (error)
 			return error;
-		}
 	}
 
-	fd_install(new_fd, get_file(file));
-	__receive_sock(file);
-	return new_fd;
+	__receive_sock(fd_prepare_file(fdf));
+	return fd_publish(fdf);
 }
 EXPORT_SYMBOL_GPL(receive_fd);
 
diff --git a/fs/namespace.c b/fs/namespace.c
index 35960fd00ee0..c58674a20cad 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3100,19 +3100,7 @@ static struct file *vfs_open_tree(int dfd, const char __user *filename, unsigned
 
 SYSCALL_DEFINE3(open_tree, int, dfd, const char __user *, filename, unsigned, flags)
 {
-	int fd;
-	struct file *file __free(fput) = NULL;
-
-	file = vfs_open_tree(dfd, filename, flags);
-	if (IS_ERR(file))
-		return PTR_ERR(file);
-
-	fd = get_unused_fd_flags(flags & O_CLOEXEC);
-	if (fd < 0)
-		return fd;
-
-	fd_install(fd, no_free_ptr(file));
-	return fd;
+	return FD_ADD(flags, vfs_open_tree(dfd, filename, flags));
 }
 
 /*
@@ -4281,10 +4269,10 @@ static unsigned int attr_flags_to_mnt_flags(u64 attr_flags)
 SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags,
 		unsigned int, attr_flags)
 {
+	struct path new_path __free(path_put) = {};
 	struct mnt_namespace *ns;
 	struct fs_context *fc;
-	struct file *file;
-	struct path newmount;
+	struct vfsmount *new_mnt;
 	struct mount *mnt;
 	unsigned int mnt_flags = 0;
 	long ret;
@@ -4322,35 +4310,36 @@ SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags,
 
 	fc = fd_file(f)->private_data;
 
-	ret = mutex_lock_interruptible(&fc->uapi_mutex);
-	if (ret < 0)
+	ACQUIRE(mutex_intr, uapi_mutex)(&fc->uapi_mutex);
+	ret = ACQUIRE_ERR(mutex_intr, &uapi_mutex);
+	if (ret)
 		return ret;
 
 	/* There must be a valid superblock or we can't mount it */
 	ret = -EINVAL;
 	if (!fc->root)
-		goto err_unlock;
+		return ret;
 
 	ret = -EPERM;
 	if (mount_too_revealing(fc->root->d_sb, &mnt_flags)) {
 		errorfcp(fc, "VFS", "Mount too revealing");
-		goto err_unlock;
+		return ret;
 	}
 
 	ret = -EBUSY;
 	if (fc->phase != FS_CONTEXT_AWAITING_MOUNT)
-		goto err_unlock;
+		return ret;
 
 	if (fc->sb_flags & SB_MANDLOCK)
 		warn_mandlock();
 
-	newmount.mnt = vfs_create_mount(fc);
-	if (IS_ERR(newmount.mnt)) {
-		ret = PTR_ERR(newmount.mnt);
-		goto err_unlock;
-	}
-	newmount.dentry = dget(fc->root);
-	newmount.mnt->mnt_flags = mnt_flags;
+	new_mnt = vfs_create_mount(fc);
+	if (IS_ERR(new_mnt))
+		return PTR_ERR(new_mnt);
+	new_mnt->mnt_flags = mnt_flags;
+
+	new_path.dentry = dget(fc->root);
+	new_path.mnt = new_mnt;
 
 	/* We've done the mount bit - now move the file context into more or
 	 * less the same state as if we'd done an fspick().  We don't want to
@@ -4360,38 +4349,27 @@ SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags,
 	vfs_clean_context(fc);
 
 	ns = alloc_mnt_ns(current->nsproxy->mnt_ns->user_ns, true);
-	if (IS_ERR(ns)) {
-		ret = PTR_ERR(ns);
-		goto err_path;
-	}
-	mnt = real_mount(newmount.mnt);
+	if (IS_ERR(ns))
+		return PTR_ERR(ns);
+	mnt = real_mount(new_path.mnt);
 	ns->root = mnt;
 	ns->nr_mounts = 1;
 	mnt_add_to_ns(ns, mnt);
-	mntget(newmount.mnt);
+	mntget(new_path.mnt);
 
-	/* Attach to an apparent O_PATH fd with a note that we need to unmount
-	 * it, not just simply put it.
-	 */
-	file = dentry_open(&newmount, O_PATH, fc->cred);
-	if (IS_ERR(file)) {
-		dissolve_on_fput(newmount.mnt);
-		ret = PTR_ERR(file);
-		goto err_path;
+	FD_PREPARE(fdf, (flags & FSMOUNT_CLOEXEC) ? O_CLOEXEC : 0,
+		   dentry_open(&new_path, O_PATH, fc->cred));
+	if (fdf.err) {
+		dissolve_on_fput(new_path.mnt);
+		return fdf.err;
 	}
-	file->f_mode |= FMODE_NEED_UNMOUNT;
 
-	ret = get_unused_fd_flags((flags & FSMOUNT_CLOEXEC) ? O_CLOEXEC : 0);
-	if (ret >= 0)
-		fd_install(ret, file);
-	else
-		fput(file);
-
-err_path:
-	path_put(&newmount);
-err_unlock:
-	mutex_unlock(&fc->uapi_mutex);
-	return ret;
+	/*
+	 * Attach to an apparent O_PATH fd with a note that we
+	 * need to unmount it, not just simply put it.
+	 */
+	fd_prepare_file(fdf)->f_mode |= FMODE_NEED_UNMOUNT;
+	return fd_publish(fdf);
 }
 
 static inline int vfs_move_mount(const struct path *from_path,
@@ -5033,19 +5011,17 @@ SYSCALL_DEFINE5(open_tree_attr, int, dfd, const char __user *, filename,
 		unsigned, flags, struct mount_attr __user *, uattr,
 		size_t, usize)
 {
-	struct file __free(fput) *file = NULL;
-	int fd;
-
 	if (!uattr && usize)
 		return -EINVAL;
 
-	file = vfs_open_tree(dfd, filename, flags);
-	if (IS_ERR(file))
-		return PTR_ERR(file);
+	FD_PREPARE(fdf, flags, vfs_open_tree(dfd, filename, flags));
+	if (fdf.err)
+		return fdf.err;
 
 	if (uattr) {
-		int ret;
 		struct mount_kattr kattr = {};
+		struct file *file = fd_prepare_file(fdf);
+		int ret;
 
 		if (flags & OPEN_TREE_CLONE)
 			kattr.kflags = MOUNT_KATTR_IDMAP_REPLACE;
@@ -5061,12 +5037,7 @@ SYSCALL_DEFINE5(open_tree_attr, int, dfd, const char __user *, filename,
 			return ret;
 	}
 
-	fd = get_unused_fd_flags(flags & O_CLOEXEC);
-	if (fd < 0)
-		return fd;
-
-	fd_install(fd, no_free_ptr(file));
-	return fd;
+	return fd_publish(fdf);
 }
 
 int show_path(struct seq_file *m, struct dentry *root)
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 1dadda82cae5..d0b9b984002f 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -1597,16 +1597,20 @@ static struct hlist_head *fanotify_alloc_merge_hash(void)
 	return hash;
 }
 
+DEFINE_CLASS(fsnotify_group,
+	     struct fsnotify_group *,
+	     if (!IS_ERR_OR_NULL(_T)) fsnotify_destroy_group(_T),
+	     fsnotify_alloc_group(ops, flags),
+	     const struct fsnotify_ops *ops, int flags)
+
 /* fanotify syscalls */
 SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 {
 	struct user_namespace *user_ns = current_user_ns();
-	struct fsnotify_group *group;
 	int f_flags, fd;
 	unsigned int fid_mode = flags & FANOTIFY_FID_BITS;
 	unsigned int class = flags & FANOTIFY_CLASS_BITS;
 	unsigned int internal_flags = 0;
-	struct file *file;
 
 	pr_debug("%s: flags=%x event_f_flags=%x\n",
 		 __func__, flags, event_f_flags);
@@ -1690,36 +1694,29 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 	if (flags & FAN_NONBLOCK)
 		f_flags |= O_NONBLOCK;
 
-	/* fsnotify_alloc_group takes a ref.  Dropped in fanotify_release */
-	group = fsnotify_alloc_group(&fanotify_fsnotify_ops,
+	CLASS(fsnotify_group, group)(&fanotify_fsnotify_ops,
 				     FSNOTIFY_GROUP_USER);
-	if (IS_ERR(group)) {
+	/* fsnotify_alloc_group takes a ref.  Dropped in fanotify_release */
+	if (IS_ERR(group))
 		return PTR_ERR(group);
-	}
 
 	/* Enforce groups limits per user in all containing user ns */
 	group->fanotify_data.ucounts = inc_ucount(user_ns, current_euid(),
 						  UCOUNT_FANOTIFY_GROUPS);
-	if (!group->fanotify_data.ucounts) {
-		fd = -EMFILE;
-		goto out_destroy_group;
-	}
+	if (!group->fanotify_data.ucounts)
+		return -EMFILE;
 
 	group->fanotify_data.flags = flags | internal_flags;
 	group->memcg = get_mem_cgroup_from_mm(current->mm);
 	group->user_ns = get_user_ns(user_ns);
 
 	group->fanotify_data.merge_hash = fanotify_alloc_merge_hash();
-	if (!group->fanotify_data.merge_hash) {
-		fd = -ENOMEM;
-		goto out_destroy_group;
-	}
+	if (!group->fanotify_data.merge_hash)
+		return -ENOMEM;
 
 	group->overflow_event = fanotify_alloc_overflow_event();
-	if (unlikely(!group->overflow_event)) {
-		fd = -ENOMEM;
-		goto out_destroy_group;
-	}
+	if (unlikely(!group->overflow_event))
+		return -ENOMEM;
 
 	if (force_o_largefile())
 		event_f_flags |= O_LARGEFILE;
@@ -1738,8 +1735,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 		group->priority = FSNOTIFY_PRIO_PRE_CONTENT;
 		break;
 	default:
-		fd = -EINVAL;
-		goto out_destroy_group;
+		return -EINVAL;
 	}
 
 	BUILD_BUG_ON(!(FANOTIFY_ADMIN_INIT_FLAGS & FAN_UNLIMITED_QUEUE));
@@ -1750,27 +1746,15 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 	}
 
 	if (flags & FAN_ENABLE_AUDIT) {
-		fd = -EPERM;
 		if (!capable(CAP_AUDIT_WRITE))
-			goto out_destroy_group;
-	}
-
-	fd = get_unused_fd_flags(f_flags);
-	if (fd < 0)
-		goto out_destroy_group;
-
-	file = anon_inode_getfile_fmode("[fanotify]", &fanotify_fops, group,
-					f_flags, FMODE_NONOTIFY);
-	if (IS_ERR(file)) {
-		put_unused_fd(fd);
-		fd = PTR_ERR(file);
-		goto out_destroy_group;
+			return -EPERM;
 	}
-	fd_install(fd, file);
-	return fd;
 
-out_destroy_group:
-	fsnotify_destroy_group(group);
+	fd = FD_ADD(f_flags,
+		    anon_inode_getfile_fmode("[fanotify]", &fanotify_fops,
+					     group, f_flags, FMODE_NONOTIFY));
+	if (fd >= 0)
+		retain_and_null_ptr(group);
 	return fd;
 }
 
diff --git a/fs/nsfs.c b/fs/nsfs.c
index a80f8d2a4122..bf27d5da91f1 100644
--- a/fs/nsfs.c
+++ b/fs/nsfs.c
@@ -110,7 +110,6 @@ int ns_get_path(struct path *path, struct task_struct *task,
 int open_namespace(struct ns_common *ns)
 {
 	struct path path __free(path_put) = {};
-	struct file *f;
 	int err;
 
 	/* call first to consume reference */
@@ -118,16 +117,7 @@ int open_namespace(struct ns_common *ns)
 	if (err < 0)
 		return err;
 
-	CLASS(get_unused_fd, fd)(O_CLOEXEC);
-	if (fd < 0)
-		return fd;
-
-	f = dentry_open(&path, O_RDONLY, current_cred());
-	if (IS_ERR(f))
-		return PTR_ERR(f);
-
-	fd_install(fd, f);
-	return take_fd(fd);
+	return FD_ADD(O_CLOEXEC, dentry_open(&path, O_RDONLY, current_cred()));
 }
 
 int open_related_ns(struct ns_common *ns,
@@ -313,7 +303,6 @@ static long ns_ioctl(struct file *filp, unsigned int ioctl,
 		struct mnt_ns_info kinfo = {};
 		struct mnt_ns_info __user *uinfo = (struct mnt_ns_info __user *)arg;
 		struct path path __free(path_put) = {};
-		struct file *f __free(fput) = NULL;
 		size_t usize = _IOC_SIZE(ioctl);
 
 		if (ns->ns_type != CLONE_NEWNS)
@@ -332,28 +321,18 @@ static long ns_ioctl(struct file *filp, unsigned int ioctl,
 		if (ret)
 			return ret;
 
-		CLASS(get_unused_fd, fd)(O_CLOEXEC);
-		if (fd < 0)
-			return fd;
-
-		f = dentry_open(&path, O_RDONLY, current_cred());
-		if (IS_ERR(f))
-			return PTR_ERR(f);
-
-		if (uinfo) {
-			/*
-			 * If @uinfo is passed return all information about the
-			 * mount namespace as well.
-			 */
-			ret = copy_ns_info_to_user(to_mnt_ns(ns), uinfo, usize, &kinfo);
-			if (ret)
-				return ret;
-		}
-
-		/* Transfer reference of @f to caller's fdtable. */
-		fd_install(fd, no_free_ptr(f));
-		/* File descriptor is live so hand it off to the caller. */
-		return take_fd(fd);
+		FD_PREPARE(fdf, O_CLOEXEC, dentry_open(&path, O_RDONLY, current_cred()));
+		if (fdf.err)
+			return fdf.err;
+		/*
+		 * If @uinfo is passed return all information about the
+		 * mount namespace as well.
+		 */
+		ret = copy_ns_info_to_user(to_mnt_ns(ns), uinfo, usize, &kinfo);
+		if (ret)
+			return ret;
+		ret = fd_publish(fdf);
+		break;
 	}
 	default:
 		ret = -ENOTTY;
diff --git a/fs/open.c b/fs/open.c
index 6a716540a96c..f328622061c5 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1416,8 +1416,8 @@ static int do_sys_openat2(int dfd, const char __user *filename,
 			  struct open_how *how)
 {
 	struct open_flags op;
-	struct filename *tmp;
-	int err, fd;
+	struct filename *tmp __free(putname) = NULL;
+	int err;
 
 	err = build_open_flags(how, &op);
 	if (unlikely(err))
@@ -1427,18 +1427,7 @@ static int do_sys_openat2(int dfd, const char __user *filename,
 	if (IS_ERR(tmp))
 		return PTR_ERR(tmp);
 
-	fd = get_unused_fd_flags(how->flags);
-	if (likely(fd >= 0)) {
-		struct file *f = do_filp_open(dfd, tmp, &op);
-		if (IS_ERR(f)) {
-			put_unused_fd(fd);
-			fd = PTR_ERR(f);
-		} else {
-			fd_install(fd, f);
-		}
-	}
-	putname(tmp);
-	return fd;
+	return FD_ADD(how->flags, do_filp_open(dfd, tmp, &op));
 }
 
 int do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
diff --git a/fs/signalfd.c b/fs/signalfd.c
index d469782f97f4..d69eab584bc6 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -250,8 +250,6 @@ static const struct file_operations signalfd_fops = {
 
 static int do_signalfd4(int ufd, sigset_t *mask, int flags)
 {
-	struct signalfd_ctx *ctx;
-
 	/* Check the SFD_* constants for consistency.  */
 	BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
 	BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
@@ -263,7 +261,8 @@ static int do_signalfd4(int ufd, sigset_t *mask, int flags)
 	signotset(mask);
 
 	if (ufd == -1) {
-		struct file *file;
+		int fd;
+		struct signalfd_ctx *ctx __free(kfree) = NULL;
 
 		ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
 		if (!ctx)
@@ -271,22 +270,16 @@ static int do_signalfd4(int ufd, sigset_t *mask, int flags)
 
 		ctx->sigmask = *mask;
 
-		ufd = get_unused_fd_flags(flags & O_CLOEXEC);
-		if (ufd < 0) {
-			kfree(ctx);
-			return ufd;
-		}
-
-		file = anon_inode_getfile_fmode("[signalfd]", &signalfd_fops,
-					ctx, O_RDWR | (flags & O_NONBLOCK),
-					FMODE_NOWAIT);
-		if (IS_ERR(file)) {
-			put_unused_fd(ufd);
-			kfree(ctx);
-			return PTR_ERR(file);
-		}
-		fd_install(ufd, file);
+		fd = FD_ADD(flags & O_CLOEXEC,
+			    anon_inode_getfile_fmode(
+				    "[signalfd]", &signalfd_fops, ctx,
+				    O_RDWR | (flags & O_NONBLOCK), FMODE_NOWAIT));
+		if (fd >= 0)
+			retain_and_null_ptr(ctx);
+		return fd;
 	} else {
+		struct signalfd_ctx *ctx;
+
 		CLASS(fd, f)(ufd);
 		if (fd_empty(f))
 			return -EBADF;
diff --git a/fs/timerfd.c b/fs/timerfd.c
index c68f28d9c426..9fcea7860ddf 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -393,9 +393,8 @@ static const struct file_operations timerfd_fops = {
 
 SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
 {
-	int ufd;
-	struct timerfd_ctx *ctx;
-	struct file *file;
+	struct timerfd_ctx *ctx __free(kfree) = NULL;
+	int ret;
 
 	/* Check the TFD_* constants for consistency.  */
 	BUILD_BUG_ON(TFD_CLOEXEC != O_CLOEXEC);
@@ -432,23 +431,13 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
 
 	ctx->moffs = ktime_mono_to_real(0);
 
-	ufd = get_unused_fd_flags(flags & TFD_SHARED_FCNTL_FLAGS);
-	if (ufd < 0) {
-		kfree(ctx);
-		return ufd;
-	}
-
-	file = anon_inode_getfile_fmode("[timerfd]", &timerfd_fops, ctx,
-			    O_RDWR | (flags & TFD_SHARED_FCNTL_FLAGS),
-			    FMODE_NOWAIT);
-	if (IS_ERR(file)) {
-		put_unused_fd(ufd);
-		kfree(ctx);
-		return PTR_ERR(file);
-	}
-
-	fd_install(ufd, file);
-	return ufd;
+	ret = FD_ADD(flags & TFD_SHARED_FCNTL_FLAGS,
+		     anon_inode_getfile_fmode("[timerfd]", &timerfd_fops, ctx,
+					      O_RDWR | (flags & TFD_SHARED_FCNTL_FLAGS),
+					      FMODE_NOWAIT));
+	if (ret >= 0)
+		retain_and_null_ptr(ctx);
+	return ret;
 }
 
 static int do_timerfd_settime(int ufd, int flags, 
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 54c6cc7fe9c6..e6e74b384087 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -2111,9 +2111,7 @@ static void init_once_userfaultfd_ctx(void *mem)
 
 static int new_userfaultfd(int flags)
 {
-	struct userfaultfd_ctx *ctx;
-	struct file *file;
-	int fd;
+	struct userfaultfd_ctx *ctx __free(kfree) = NULL;
 
 	VM_WARN_ON_ONCE(!current->mm);
 
@@ -2135,26 +2133,18 @@ static int new_userfaultfd(int flags)
 	atomic_set(&ctx->mmap_changing, 0);
 	ctx->mm = current->mm;
 
-	fd = get_unused_fd_flags(flags & UFFD_SHARED_FCNTL_FLAGS);
-	if (fd < 0)
-		goto err_out;
+	FD_PREPARE(fdf, flags & UFFD_SHARED_FCNTL_FLAGS,
+		   anon_inode_create_getfile("[userfaultfd]", &userfaultfd_fops, ctx,
+					     O_RDONLY | (flags & UFFD_SHARED_FCNTL_FLAGS),
+					     NULL));
+	if (fdf.err)
+		return fdf.err;
 
-	/* Create a new inode so that the LSM can block the creation.  */
-	file = anon_inode_create_getfile("[userfaultfd]", &userfaultfd_fops, ctx,
-			O_RDONLY | (flags & UFFD_SHARED_FCNTL_FLAGS), NULL);
-	if (IS_ERR(file)) {
-		put_unused_fd(fd);
-		fd = PTR_ERR(file);
-		goto err_out;
-	}
 	/* prevent the mm struct to be freed */
 	mmgrab(ctx->mm);
-	file->f_mode |= FMODE_NOWAIT;
-	fd_install(fd, file);
-	return fd;
-err_out:
-	kmem_cache_free(userfaultfd_ctx_cachep, ctx);
-	return fd;
+	fd_prepare_file(fdf)->f_mode |= FMODE_NOWAIT;
+	retain_and_null_ptr(ctx);
+	return fd_publish(fdf);
 }
 
 static inline bool userfaultfd_syscall_allowed(int flags)
diff --git a/fs/xfs/xfs_handle.c b/fs/xfs/xfs_handle.c
index f19fce557354..5a3e3bf4e7cc 100644
--- a/fs/xfs/xfs_handle.c
+++ b/fs/xfs/xfs_handle.c
@@ -233,14 +233,11 @@ xfs_open_by_handle(
 	xfs_fsop_handlereq_t	*hreq)
 {
 	const struct cred	*cred = current_cred();
-	int			error;
-	int			fd;
 	int			permflag;
-	struct file		*filp;
 	struct inode		*inode;
 	struct dentry		*dentry;
 	fmode_t			fmode;
-	struct path		path;
+	struct path		path __free(path_put) = {};
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
@@ -249,12 +246,11 @@ xfs_open_by_handle(
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);
 	inode = d_inode(dentry);
+	path.dentry = dentry;
 
 	/* Restrict xfs_open_by_handle to directories & regular files. */
-	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))) {
-		error = -EPERM;
-		goto out_dput;
-	}
+	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
+		return -EPERM;
 
 #if BITS_PER_LONG != 32
 	hreq->oflags |= O_LARGEFILE;
@@ -263,48 +259,30 @@ xfs_open_by_handle(
 	permflag = hreq->oflags;
 	fmode = OPEN_FMODE(permflag);
 	if ((!(permflag & O_APPEND) || (permflag & O_TRUNC)) &&
-	    (fmode & FMODE_WRITE) && IS_APPEND(inode)) {
-		error = -EPERM;
-		goto out_dput;
-	}
+	    (fmode & FMODE_WRITE) && IS_APPEND(inode))
+		return -EPERM;
 
-	if ((fmode & FMODE_WRITE) && IS_IMMUTABLE(inode)) {
-		error = -EPERM;
-		goto out_dput;
-	}
+	if ((fmode & FMODE_WRITE) && IS_IMMUTABLE(inode))
+		return -EPERM;
 
 	/* Can't write directories. */
-	if (S_ISDIR(inode->i_mode) && (fmode & FMODE_WRITE)) {
-		error = -EISDIR;
-		goto out_dput;
-	}
+	if (S_ISDIR(inode->i_mode) && (fmode & FMODE_WRITE))
+		return -EISDIR;
 
-	fd = get_unused_fd_flags(0);
-	if (fd < 0) {
-		error = fd;
-		goto out_dput;
-	}
+	path.mnt = mntget(parfilp->f_path.mnt);
 
-	path.mnt = parfilp->f_path.mnt;
-	path.dentry = dentry;
-	filp = dentry_open(&path, hreq->oflags, cred);
-	dput(dentry);
-	if (IS_ERR(filp)) {
-		put_unused_fd(fd);
-		return PTR_ERR(filp);
-	}
+	FD_PREPARE(fdf, 0, dentry_open(&path, hreq->oflags, cred));
+	if (fdf.err)
+		return fdf.err;
 
 	if (S_ISREG(inode->i_mode)) {
+		struct file *filp = fd_prepare_file(fdf);
+
 		filp->f_flags |= O_NOATIME;
 		filp->f_mode |= FMODE_NOCMTIME;
 	}
 
-	fd_install(fd, filp);
-	return fd;
-
- out_dput:
-	dput(dentry);
-	return error;
+	return fd_publish(fdf);
 }
 
 int