[PATCH v7 8/8] fsdax: add exception for reflinked files

[Shiyang Ruan]

For reflinked files, one dax page may be associated more than once with
different fime mapping and index.  It will report warning.  Now, since
we have introduced dax-RMAP for this case and also have to keep its
functionality for other filesystems who are not support rmap, I add this
exception here.

Signed-off-by: Shiyang Ruan <ruansy.f...@fujitsu.com>
---
 fs/dax.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 2536c105ec7f..1a57211b1bc9 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -352,9 +352,10 @@ static void dax_associate_entry(void *entry, struct 
address_space *mapping,
        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++;
+               if (!page->mapping) {
+                       page->mapping = mapping;
+                       page->index = index + i++;
+               }
        }
 }
 
@@ -370,9 +371,10 @@ static void dax_disassociate_entry(void *entry, struct 
address_space *mapping,
                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;
+               if (page->mapping == mapping) {
+                       page->mapping = NULL;
+                       page->index = 0;
+               }
        }
 }
 
-- 
2.33.0