[Ocfs2-devel] [PATCH 4/4] ocfs2: limit the number of inodes in orphanscan

[Wengang Wang]

Hi Joel,

On 11-08-21 21:47, Joel Becker wrote:
> On Fri, Jul 29, 2011 at 06:06:23PM +0800, Wengang Wang wrote:
> > During orphanscan, limit the scan number in a single loop to avoid OOM.
> 
> How does this OOM?  Please explain this in the patch and in the patch
> description.  Or, conversely, free the resources the orphan scan is done
> using.

Explaination why it OOM:
In current code, when recoverying orphan dirs, we are doing it like this:

lock orphandir
read out all the inodes under the orphandir to a list
unlock the orphandir
#above see ocfs2_queue_orphans()
and the iput all the inodes in the list to delete the on disk inode
#above see ocfs2_recover_orphans()

For normal case, there are no many files under orphandir, there is no problem.
But for an extreme case, there are a huge number of files under orphandir,
huge size of memory is needed to hold the inodes. It is possible to exhaust
memory, then OOM occurs.

The fix in this patch depends on patch
  "ocfs2: ocfs2_dir_foreach returns the error turned by filldir"
Since NAK for that patch, please ignore this too.

thanks,
wengang.
 
> Joel
> 
> >