[PATCH 20/39] ovl: add ovl_fallocate()

[Miklos Szeredi]

Implement stacked fallocate.

Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
---
 fs/overlayfs/file.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 4057bbf2e141..069599d53511 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -282,6 +282,29 @@ static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
 	return ret;
 }
 
+static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
+{
+	struct inode *inode = file_inode(file);
+	struct fd real;
+	const struct cred *old_cred;
+	int ret;
+
+	ret = ovl_real_fdget(file, &real);
+	if (ret)
+		return ret;
+
+	old_cred = ovl_override_creds(file_inode(file)->i_sb);
+	ret = vfs_fallocate(real.file, mode, offset, len);
+	revert_creds(old_cred);
+
+	/* Update size */
+	ovl_copyattr(ovl_inode_real(inode), inode);
+
+	fdput(real);
+
+	return ret;
+}
+
 const struct file_operations ovl_file_operations = {
 	.open		= ovl_open,
 	.release	= ovl_release,
@@ -290,4 +313,5 @@ const struct file_operations ovl_file_operations = {
 	.write_iter	= ovl_write_iter,
 	.fsync		= ovl_fsync,
 	.mmap		= ovl_mmap,
+	.fallocate	= ovl_fallocate,
 };
-- 
2.14.3