[PATCH 3/3] xfs: cancel COW in xfs_cancel_ioend

[Christoph Hellwig]

On Wed, Jan 06, 2016 at 04:32:27PM -0800, Darrick J. Wong wrote:
> Ok.  I spent a couple of days trying to find all the places where we need to
> delete CoW reservations (hole punch, truncate, etc.) and found some places
> where the code was leaving reservations behind in the CoW fork (most notable
> truncate).  I also made the inode eviction code purge any CoW leftovers, so
> that should all go away.

Can you send that part out for NFS testing?

> I also wrote some more xfstests that try to hit all the CoW-cancelling code
> paths (fpunch, fzero, fcollapse, finsert, truncate, -EIO) to smoke test all
> that.  By the way, do you have a testcase handy for the "non-blocking writeback
> EAGAIN" case?  I'm guessing that we could hit that pretty easily by lowering
> dirty_background_* and dirtying a lot of pages while reflinking?

I did hit it pretty easily testing over NFS to a local nfs server with
xfstests.