On Tue, 13 Mar 2018 06:25:38 -0700 Matthew Wilcox [off-list ref] wrote:

This patchset is, I believe, appropriate for merging for 4.17.
It contains the XArray implementation, to eventually replace the radix
tree, and converts the page cache to use it.

I looked at this from a for-4.17 POV and ran out of nerve at "[PATCH v9
09/61] xarray: Replace exceptional entries".  It's awfully late.

"[PATCH v9 08/61] page cache: Use xa_lock" looks sufficiently
mechanical to be if-it-compiles-it-works, although perhaps that
shouldn't be in 4.17 either.  Mainly because it commits us to merging
the rest of XArray and there hasn't been a ton of review and test
activity.



It looks like btrfs has changed in -next:

--- a/fs/btrfs/inode.c~page-cache-use-xa_lock-fix
+++ a/fs/btrfs/inode.c

@@ -7445,7 +7445,7 @@ out:
 
 bool btrfs_page_exists_in_range(struct inode *inode, loff_t start, loff_t end)
 {
-	struct radix_tree_root *root = &inode->i_mapping->page_tree;
+	struct radix_tree_root *root = &inode->i_mapping->i_pages;
 	bool found = false;
 	void **pagep = NULL;
 	struct page *page = NULL;

_