On Wed, 24 Aug 2016 14:37:12 -0600 Ross Zwisler <ross.zwis...@linux.intel.com> wrote:
> For DAX inodes we need to be careful to never have page cache pages in the > mapping->page_tree. This radix tree should be composed only of DAX > exceptional entries and zero pages. > > ltp's readahead02 test was triggering a warning because we were trying to > insert a DAX exceptional entry but found that a page cache page had already > been inserted into the tree. This page was being inserted into the radix > tree in response to a readahead(2) call. > > Readahead doesn't make sense for DAX inodes, but we don't want it to report > a failure either. Instead, we just return success and don't do any work. > > --- a/mm/readahead.c > +++ b/mm/readahead.c > @@ -8,6 +8,7 @@ > */ > > #include <linux/kernel.h> > +#include <linux/dax.h> > #include <linux/gfp.h> > #include <linux/export.h> > #include <linux/blkdev.h> > @@ -544,6 +545,9 @@ do_readahead(struct address_space *mapping, struct file > *filp, > if (!mapping || !mapping->a_ops) > return -EINVAL; > > + if (dax_mapping(mapping)) > + return 0; > + Please don't force readers to go spend minutes putzing around in the git tree trying to understand your code. /* these things considered useful! */
