4.7-stable review patch. If anyone has any objections, please let me know.
------------------ From: Ross Zwisler <[email protected]> commit 11bd969fdefea3ac0cb9791224f1e09784e21e58 upstream. 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. Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ross Zwisler <[email protected]> Reported-by: Jeff Moyer <[email protected]> Cc: Dan Williams <[email protected]> Cc: Dave Chinner <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Jan Kara <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- mm/readahead.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- 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> @@ -545,6 +546,14 @@ do_readahead(struct address_space *mappi if (!mapping || !mapping->a_ops) return -EINVAL; + /* + * 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. + */ + if (dax_mapping(mapping)) + return 0; + return force_page_cache_readahead(mapping, filp, index, nr); }
