Move unshare_fd() where the rest of the descriptor table lifecycle
helpers live.

No functional changes.

Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
 fs/file.c               | 18 ++++++++++++++++++
 include/linux/fdtable.h |  1 +
 kernel/fork.c           | 18 ------------------
 3 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/fs/file.c b/fs/file.c
index 345011dad472..636a87e527b3 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -471,6 +471,24 @@ struct files_struct *dup_fd(struct files_struct *oldf, struct fd_range *punch_ho
 	return newf;
 }
 
+/*
+ * Unshare file descriptor table if it is being shared
+ */
+int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
+{
+	struct files_struct *fd = current->files;
+
+	if ((unshare_flags & CLONE_FILES) &&
+	    (fd && atomic_read(&fd->count) > 1)) {
+		fd = dup_fd(fd, NULL);
+		if (IS_ERR(fd))
+			return PTR_ERR(fd);
+		*new_fdp = fd;
+	}
+
+	return 0;
+}
+
 static struct fdtable *close_files(struct files_struct * files)
 {
 	/*
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index 9614c6ecd477..4ee1598848bb 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -102,6 +102,7 @@ struct task_struct;
 void put_files_struct(struct files_struct *fs);
 void switch_files_struct(struct task_struct *tsk, struct files_struct *files);
 int unshare_files(void);
+int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp);
 struct fd_range {
 	unsigned int from, to;
 };
diff --git a/kernel/fork.c b/kernel/fork.c
index 7c6fe82dbb9f..fddba55bbc14 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -3207,24 +3207,6 @@ static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
 	return 0;
 }
 
-/*
- * Unshare file descriptor table if it is being shared
- */
-static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
-{
-	struct files_struct *fd = current->files;
-
-	if ((unshare_flags & CLONE_FILES) &&
-	    (fd && atomic_read(&fd->count) > 1)) {
-		fd = dup_fd(fd, NULL);
-		if (IS_ERR(fd))
-			return PTR_ERR(fd);
-		*new_fdp = fd;
-	}
-
-	return 0;
-}
-
 /*
  * unshare allows a process to 'unshare' part of the process
  * context which was originally shared using clone.  copy_*

-- 
2.53.0