[PATCH v5 06/25] fs/dax: Always remove DAX page-cache entries when breaking layouts

@@ -845,6 +845,36 @@ int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
 	return ret;
 }
 
+void dax_delete_mapping_range(struct address_space *mapping,
+				loff_t start, loff_t end)
+{
+	void *entry;
+	pgoff_t start_idx = start >> PAGE_SHIFT;
+	pgoff_t end_idx;
+	XA_STATE(xas, &mapping->i_pages, start_idx);
+
+	/* If end == LLONG_MAX, all pages from start to till end of file */
+	if (end == LLONG_MAX)
+		end_idx = ULONG_MAX;
+	else
+		end_idx = end >> PAGE_SHIFT;
+
+	xas_lock_irq(&xas);
+	xas_for_each(&xas, entry, end_idx) {
+		if (!xa_is_value(entry))
+			continue;
+		entry = wait_entry_unlocked_exclusive(&xas, entry);
+		if (!entry)
+			continue;
+		dax_disassociate_entry(entry, mapping, true);
+		xas_store(&xas, NULL);
+		mapping->nrpages -= 1UL << dax_entry_order(entry);
+		put_unlocked_entry(&xas, entry, WAKE_ALL);
+	}
+	xas_unlock_irq(&xas);
+}
+EXPORT_SYMBOL_GPL(dax_delete_mapping_range);
+
 static int wait_page_idle(struct page *page,
 			void (cb)(struct inode *),
 			struct inode *inode)

@@ -874,6 +904,9 @@ int dax_break_mapping(struct inode *inode, loff_t start, loff_t end,
 		error = wait_page_idle(page, cb, inode);
 	} while (error == 0);
 
+	if (!page)
+		dax_delete_mapping_range(inode->i_mapping, start, end);
+
 	return error;
 }
 EXPORT_SYMBOL_GPL(dax_break_mapping);

@@ -2746,6 +2746,12 @@ xfs_mmaplock_two_inodes_and_break_dax_layout(
 		goto again;
 	}
 
+	/*
+	 * Normally xfs_break_dax_layouts() would delete the mapping entries as well so
+	 * do that here.
+	 */
+	dax_delete_mapping_range(VFS_I(ip2)->i_mapping, 0, LLONG_MAX);
+
 	return 0;
 }
 

@@ -263,6 +263,8 @@ vm_fault_t dax_iomap_fault(struct vm_fault *vmf, unsigned int order,
 vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf,
 		unsigned int order, pfn_t pfn);
 int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
+void dax_delete_mapping_range(struct address_space *mapping,
+				loff_t start, loff_t end);
 int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
 				      pgoff_t index);
 int __must_check dax_break_mapping(struct inode *inode, loff_t start,

@@ -78,8 +78,22 @@ static void truncate_folio_batch_exceptionals(struct address_space *mapping,
 
 	if (dax_mapping(mapping)) {
 		for (i = j; i < nr; i++) {
-			if (xa_is_value(fbatch->folios[i]))
+			if (xa_is_value(fbatch->folios[i])) {
+				/*
+				 * File systems should already have called
+				 * dax_break_mapping_entry() to remove all DAX
+				 * entries while holding a lock to prevent
+				 * establishing new entries. Therefore we
+				 * shouldn't find any here.
+				 */
+				WARN_ON_ONCE(1);
+
+				/*
+				 * Delete the mapping so truncate_pagecache()
+				 * doesn't loop forever.
+				 */
 				dax_delete_mapping_entry(mapping, indices[i]);
+			}
 		}
 		goto out;
 	}