[PATCH v2 16/35] ovl: add ovl_mmap()

[Miklos Szeredi]

Implement stacked mmap.

Signed-off-by: Miklos Szeredi <mszer...@redhat.com>
---
 fs/overlayfs/file.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 419aa3f9967b..b75ee0a3655e 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -252,6 +252,33 @@ static int ovl_fsync(struct file *file, loff_t start, 
loff_t end, int datasync)
        return ret;
 }
 
+static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
+{
+       struct fd real;
+       const struct cred *old_cred;
+       int ret;
+
+       ret = ovl_real_fdget(file, &real);
+       if (ret)
+               return ret;
+
+       /* transfer ref: */
+       fput(vma->vm_file);
+       vma->vm_file = get_file(real.file);
+       fdput(real);
+
+       if (!vma->vm_file->f_op->mmap)
+               return -ENODEV;
+
+       old_cred = ovl_override_creds(file_inode(file)->i_sb);
+       ret = call_mmap(vma->vm_file, vma);
+       revert_creds(old_cred);
+
+       ovl_file_accessed(file);
+
+       return ret;
+}
+
 const struct file_operations ovl_file_operations = {
        .open           = ovl_open,
        .release        = ovl_release,
@@ -259,4 +286,5 @@ const struct file_operations ovl_file_operations = {
        .read_iter      = ovl_read_iter,
        .write_iter     = ovl_write_iter,
        .fsync          = ovl_fsync,
+       .mmap           = ovl_mmap,
 };
-- 
2.14.3