On Wed, 2007-10-31 at 14:26 +1100, Nick Piggin wrote:

On Wednesday 31 October 2007 03:04, Peter Zijlstra wrote:

quoted

Hi,

Another posting of the full swap over NFS series.

Hi,

Is it really worth all the added complexity of making swap
over NFS files work, given that you could use a network block
device instead?

As it stands, we don't have a usable network block device IMHO.
NFS is by far the most used and usable network storage solution out
there, anybody with half a brain knows how to set it up and use it.

Also, have you ensured that page_file_index, page_file_mapping
and page_offset are only ever used on anonymous pages when the
page is locked? (otherwise PageSwapCache could change)

Good point, I hope so, both ->readpage() and ->writepage() take a locked
page, I'd have to look if it remains locked throughout the NFS call
chain.

Then again, it might become obsolete with the extended swap a_ops.