mm/truncate: add folio_unmap_invalidate() helper

Add a folio_unmap_invalidate() helper, which unmaps and invalidates a
given folio.  The caller must already have locked the folio.  Embed the
old invalidate_complete_folio2() helper in there as well, as nobody else
calls it.

Use this new helper in invalidate_inode_pages2_range(), rather than
duplicate the code there.

In preparation for using this elsewhere as well, have it take a gfp_t mask
rather than assume GFP_KERNEL is the right choice.  This bubbles back to
invalidate_complete_folio2() as well.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
Cc: Brian Foster <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: axboe

mm/internal.h

@@ -392,6 +392,8 @@ void unmap_page_range(struct mmu_gather *tlb,
 			     struct vm_area_struct *vma,
 			     unsigned long addr, unsigned long end,
 			     struct zap_details *details);
+int folio_unmap_invalidate(struct address_space *mapping, struct folio *folio,
+			   gfp_t gfp);
 
 void page_cache_ra_order(struct readahead_control *, struct file_ra_state *,
 		unsigned int order);

mm/truncate.c

@@ -525,21 +525,42 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping,
 }
 EXPORT_SYMBOL(invalidate_mapping_pages);
 
+static int folio_launder(struct address_space *mapping, struct folio *folio)
+{
+	if (!folio_test_dirty(folio))
+		return 0;
+	if (folio->mapping != mapping || mapping->a_ops->launder_folio == NULL)
+		return 0;
+	return mapping->a_ops->launder_folio(folio);
+}
+
 /*
  * This is like mapping_evict_folio(), except it ignores the folio's
  * refcount.  We do this because invalidate_inode_pages2() needs stronger
  * invalidation guarantees, and cannot afford to leave folios behind because
  * shrink_folio_list() has a temp ref on them, or because they're transiently
  * sitting in the folio_add_lru() caches.
  */
-static int invalidate_complete_folio2(struct address_space *mapping,
-					struct folio *folio)
+int folio_unmap_invalidate(struct address_space *mapping, struct folio *folio,
+			   gfp_t gfp)
 {
-	if (folio->mapping != mapping)
-		return 0;
+	int ret;
+
+	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
 
-	if (!filemap_release_folio(folio, GFP_KERNEL))
+	if (folio_test_dirty(folio))
 		return 0;
+	if (folio_mapped(folio))
+		unmap_mapping_folio(folio);
+	BUG_ON(folio_mapped(folio));
+
+	ret = folio_launder(mapping, folio);
+	if (ret)
+		return ret;
+	if (folio->mapping != mapping)
+		return -EBUSY;
+	if (!filemap_release_folio(folio, gfp))
+		return -EBUSY;
 
 	spin_lock(&mapping->host->i_lock);
 	xa_lock_irq(&mapping->i_pages);
@@ -558,16 +579,7 @@ static int invalidate_complete_folio2(struct address_space *mapping,
 failed:
 	xa_unlock_irq(&mapping->i_pages);
 	spin_unlock(&mapping->host->i_lock);
-	return 0;
-}
-
-static int folio_launder(struct address_space *mapping, struct folio *folio)
-{
-	if (!folio_test_dirty(folio))
-		return 0;
-	if (folio->mapping != mapping || mapping->a_ops->launder_folio == NULL)
-		return 0;
-	return mapping->a_ops->launder_folio(folio);
+	return -EBUSY;
 }
 
 /**
@@ -631,16 +643,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
 			}
 			VM_BUG_ON_FOLIO(!folio_contains(folio, indices[i]), folio);
 			folio_wait_writeback(folio);
-
-			if (folio_mapped(folio))
-				unmap_mapping_folio(folio);
-			BUG_ON(folio_mapped(folio));
-
-			ret2 = folio_launder(mapping, folio);
-			if (ret2 == 0) {
-				if (!invalidate_complete_folio2(mapping, folio))
-					ret2 = -EBUSY;
-			}
+			ret2 = folio_unmap_invalidate(mapping, folio, GFP_KERNEL);
 			if (ret2 < 0)
 				ret = ret2;
 			folio_unlock(folio);