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    Subject[PATCH 19/39] ovl: add ovl_mmap()
    Date
    Implement stacked mmap.

    Signed-off-by: Miklos Szeredi <mszeredi@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 7b47dce4b072..4057bbf2e141 100644
    --- a/fs/overlayfs/file.c
    +++ b/fs/overlayfs/file.c
    @@ -255,6 +255,33 @@ 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,
    @@ -262,4 +289,5 @@ 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
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