[PATCHv3 25/29] truncate: handle file thp

[Kirill A. Shutemov]

For shmem/tmpfs we only need to tweak truncate_inode_page() and
invalidate_mapping_pages().

Signed-off-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com>
---
 mm/truncate.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/mm/truncate.c b/mm/truncate.c
index 7598b552ae03..40d3730a8e62 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -157,10 +157,14 @@ invalidate_complete_page(struct address_space *mapping, 
struct page *page)
 
 int truncate_inode_page(struct address_space *mapping, struct page *page)
 {
+       loff_t holelen;
+       VM_BUG_ON_PAGE(PageTail(page), page);
+
+       holelen = PageTransHuge(page) ? HPAGE_PMD_SIZE : PAGE_CACHE_SIZE;
        if (page_mapped(page)) {
                unmap_mapping_range(mapping,
                                   (loff_t)page->index << PAGE_CACHE_SHIFT,
-                                  PAGE_CACHE_SIZE, 0);
+                                  holelen, 0);
        }
        return truncate_complete_page(mapping, page);
 }
@@ -489,7 +493,21 @@ unsigned long invalidate_mapping_pages(struct 
address_space *mapping,
 
                        if (!trylock_page(page))
                                continue;
-                       WARN_ON(page->index != index);
+
+                       WARN_ON(page_to_pgoff(page) != index);
+
+                       /* Middle of THP: skip */
+                       if (PageTransTail(page)) {
+                               unlock_page(page);
+                               continue;
+                       } else if (PageTransHuge(page)) {
+                               index += HPAGE_PMD_NR - 1;
+                               i += HPAGE_PMD_NR - 1;
+                               /* 'end' is in the middle of THP */
+                               if (index ==  round_down(end, HPAGE_PMD_NR))
+                                       continue;
+                       }
+
                        ret = invalidate_inode_page(page);
                        unlock_page(page);
                        /*
-- 
2.7.0