Re: xfs_iext_realloc_indirect and "XFS: possible memory allocation deadlock"

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

On Tue, Jul 07, 2015 at 10:09:11AM +1000, Dave Chinner wrote:
> server crash. i.e. the client side commit is an "fsync" to the
> server, and until the server responds with a success to the client
> commit RPC the client side will continue to retry sending the data
> to the server.
> 
> For the persepctive of metadata (i.e. directory entries) the use of
> the "dirsync" mount option is sufficient for HA failover servers to
> work correctly as it ensures that directory structure changes are always
> committed to disk before the RPC response is sent back to the
> client.
> 
> i.e. the "sync" mount option doesn't actually improve data integrity
> of an NFS server when you look at the end-to-end NFS protocol
> handling of async write data....


You don't need dirsync either.  NFS does the right sync usin the
commit_metadata export operation without using that big hammer.