Messages in this thread | | | Date | Thu, 15 Dec 2011 13:55:50 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH 1/1] do_truncate needs to increment iversion |
| |
On Wed, 14 Dec 2011 18:44:57 +0200 Dmitry Kasatkin <dmitry.kasatkin@intel.com> wrote:
> IMA/EVM uses iversion to identify if file content has been changed. > It has been found that when file is opened, truncated with ftruncate() > and then closed, iversion is not updated. > > This patch adds iversion incrementation to do_truncate().
I confess that I've never really fully understood what i_version is supposed to do, so I'm not in any position to comment on where, when and why the thing should be updated.
At present it gets updated in file_update_time() so I suppose that we're not calling file_update_time() in the ftruncate case, which sounds wrong?
It's notable that file_update_time() will not update i_version if the inode has NOCMTIME. This might be wrong, but one would need to know the intent of i_version to be able to say. Do your files have S_NOCMTIME set?
> --- a/fs/open.c > +++ b/fs/open.c > @@ -56,6 +56,8 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs, > newattrs.ia_valid |= ret | ATTR_FORCE; > > mutex_lock(&dentry->d_inode->i_mutex); > + if (IS_I_VERSION(dentry->d_inode)) > + inode_inc_iversion(dentry->d_inode); > ret = notify_change(dentry, &newattrs); > mutex_unlock(&dentry->d_inode->i_mutex); > return ret;
With four evaluations, it is time to cache dentry->d_inode in a local.
| |