[RFC PATCH v2 6/6] fsdax: remove useless (dis)associate functions

[Shiyang Ruan]

Since owner tarcking is triggerred by pmem device, these functions are
useless.  So remove it.

Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxxxxx>
---
 fs/dax.c | 46 ----------------------------------------------
 1 file changed, 46 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 34471acde683..6c037287cb04 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -323,48 +323,6 @@ static unsigned long dax_end_pfn(void *entry)
 	for (pfn = dax_to_pfn(entry); \
 			pfn < dax_end_pfn(entry); pfn++)
 
-/*
- * TODO: for reflink+dax we need a way to associate a single page with
- * multiple address_space instances at different linear_page_index()
- * offsets.
- */
-static void dax_associate_entry(void *entry, struct address_space *mapping,
-		struct vm_area_struct *vma, unsigned long address)
-{
-	unsigned long size = dax_entry_size(entry), pfn, index;
-	int i = 0;
-
-	if (IS_ENABLED(CONFIG_FS_DAX_LIMITED))
-		return;
-
-	index = linear_page_index(vma, address & ~(size - 1));
-	for_each_mapped_pfn(entry, pfn) {
-		struct page *page = pfn_to_page(pfn);
-
-		WARN_ON_ONCE(page->mapping);
-		page->mapping = mapping;
-		page->index = index + i++;
-	}
-}
-
-static void dax_disassociate_entry(void *entry, struct address_space *mapping,
-		bool trunc)
-{
-	unsigned long pfn;
-
-	if (IS_ENABLED(CONFIG_FS_DAX_LIMITED))
-		return;
-
-	for_each_mapped_pfn(entry, pfn) {
-		struct page *page = pfn_to_page(pfn);
-
-		WARN_ON_ONCE(trunc && page_ref_count(page) > 1);
-		WARN_ON_ONCE(page->mapping && page->mapping != mapping);
-		page->mapping = NULL;
-		page->index = 0;
-	}
-}
-
 static struct page *dax_busy_page(void *entry)
 {
 	unsigned long pfn;
@@ -516,7 +474,6 @@ static void *grab_mapping_entry(struct xa_state *xas,
 			xas_lock_irq(xas);
 		}
 
-		dax_disassociate_entry(entry, mapping, false);
 		xas_store(xas, NULL);	/* undo the PMD join */
 		dax_wake_entry(xas, entry, true);
 		mapping->nrexceptional--;
@@ -653,7 +610,6 @@ static int __dax_invalidate_entry(struct address_space *mapping,
 	    (xas_get_mark(&xas, PAGECACHE_TAG_DIRTY) ||
 	     xas_get_mark(&xas, PAGECACHE_TAG_TOWRITE)))
 		goto out;
-	dax_disassociate_entry(entry, mapping, trunc);
 	xas_store(&xas, NULL);
 	mapping->nrexceptional--;
 	ret = 1;
@@ -747,8 +703,6 @@ static void *dax_insert_entry(struct xa_state *xas,
 	if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
 		void *old;
 
-		dax_disassociate_entry(entry, mapping, false);
-		dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address);
 		/*
 		 * Only swap our new entry into the page cache if the current
 		 * entry is a zero page or an empty entry.  If a normal PTE or
-- 
2.29.2