[RFC PATCH 17/35] ovl: readd fiemap

[Miklos Szeredi]

Implement stacked fiemap().

Need to split inode operations for regular file (which has fiemap) and
special file (which doesn't have fiemap).

Signed-off-by: Miklos Szeredi <mszer...@redhat.com>
---
 fs/overlayfs/inode.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 3b996639e1ad..b723327501f7 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -455,6 +455,23 @@ int ovl_update_time(struct inode *inode, struct timespec 
*ts, int flags)
        return 0;
 }
 
+static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
+                     u64 start, u64 len)
+{
+       int err;
+       struct inode *realinode = ovl_inode_real(inode);
+       const struct cred *old_cred;
+
+       if (!realinode->i_op->fiemap)
+               return -EOPNOTSUPP;
+
+       old_cred = ovl_override_creds(inode->i_sb);
+       err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
+       revert_creds(old_cred);
+
+       return err;
+}
+
 static const struct inode_operations ovl_file_inode_operations = {
        .setattr        = ovl_setattr,
        .permission     = ovl_permission,
@@ -462,6 +479,7 @@ static const struct inode_operations 
ovl_file_inode_operations = {
        .listxattr      = ovl_listxattr,
        .get_acl        = ovl_get_acl,
        .update_time    = ovl_update_time,
+       .fiemap         = ovl_fiemap,
 };
 
 static const struct inode_operations ovl_symlink_inode_operations = {
@@ -472,6 +490,15 @@ static const struct inode_operations 
ovl_symlink_inode_operations = {
        .update_time    = ovl_update_time,
 };
 
+static const struct inode_operations ovl_special_inode_operations = {
+       .setattr        = ovl_setattr,
+       .permission     = ovl_permission,
+       .getattr        = ovl_getattr,
+       .listxattr      = ovl_listxattr,
+       .get_acl        = ovl_get_acl,
+       .update_time    = ovl_update_time,
+};
+
 /*
  * It is possible to stack overlayfs instance on top of another
  * overlayfs instance as lower layer. We need to annonate the
@@ -555,7 +582,7 @@ static void ovl_fill_inode(struct inode *inode, umode_t 
mode, dev_t rdev,
                break;
 
        default:
-               inode->i_op = &ovl_file_inode_operations;
+               inode->i_op = &ovl_special_inode_operations;
                init_special_inode(inode, mode, rdev);
                break;
        }
-- 
2.14.3