Re: [patch 38/52] fs: icache RCU free inodes

Nick Piggin
2010-06-30T14:33:26Z

On Wed, Jun 30, 2010 at 06:57:11PM +1000, Dave Chinner wrote:
> On Thu, Jun 24, 2010 at 01:02:50PM +1000, npiggin@suse.de wrote:
> > RCU free the struct inode. This will allow:
>
> Rather than what it will allow, what are the constraints this
> imposes on allocating and freeing a struct inode? e.g. XFS embeds
> the struct inode in a larger inode structure and does it's own
> allocation, caching and freeing of the larger structure outside of
> the VFS functionality.
>
> Does this need to be converted to RCU? Do we need to do more
> initialisation of the struct inode than we currently do? What
> functions/call chains now implicitly require RCU freeing semantics
> on the struct inode for safe operation? What else do we need to be
> aware of?

Yeah, filesystems with their own freeing functions will need to
do a call_rcu to free it (many are not converted). Otherwise,
there is nothing else to know. They could take advantage of RCU
if they would like though.