Re: [RFC][PATCH 3/5] check files for checkpointability

Serge E. Hallyn
2009-02-23T23:49:25Z

Quoting Dave Hansen (dave@linux.vnet.ibm.com):
>
> Introduce a files_struct counter to indicate whether a particular
> file_struct has ever contained a file which can not be
> checkpointed. This flag is a one-way trip; once it is set, it may
> not be unset.
>
> We assume at allocation that a new files_struct is clean and may
> be checkpointed. However, as soon as it has had its files filled
> from its parent's, we check it for real in __scan_files_for_cr().
> At that point, we mark it if it contained any uncheckpointable
> files.
>
> We also check each 'struct file' when it is installed in a fd
> slot. This way, if anyone open()s or managed to dup() an
> unsuppored file, we can catch it.

So what is the point of tagging the files_struct counter and
making it a one-way trip? Why not just check every file at
checkpoint time?

-serge