ovl: respect FIEMAP_FLAG_SYNC flag

Stacked overlayfs fiemap operation broke xfstests that test delayed
allocation (with "_test_generic_punch -d"), because ovl_fiemap()
failed to write dirty pages when requested.

Fixes: 9e142c4102db ("ovl: add ovl_fiemap()")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index e0bb217c01e2a6c8389bf9ec2dfb2f56f0fab7c8..5014749fd4b45d346f9c3d4f13495814437cf3d2 100644 (file)
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -467,6 +467,10 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                return -EOPNOTSUPP;
 
        old_cred = ovl_override_creds(inode->i_sb);
+
+       if (fieinfo->fi_flags & FIEMAP_FLAG_SYNC)
+               filemap_write_and_wait(realinode->i_mapping);
+
        err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
        revert_creds(old_cred);