[PATCH] Make address_space_operations->invalidatepage return void

The return value of this function is never used, so let's be honest and
declare it as void.

Some places where invalidatepage returned 0, I have inserted comments
suggesting a BUG_ON.

[[e-mail]: JBD BUG fix]
[[e-mail]: rework for git-nfs]
[[e-mail]: don't go BUG in block_invalidate_page()]
Signed-off-by: Neil Brown <[e-mail]>
Acked-by: Dave Kleikamp <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

fs/afs/file.c

···
 #endif
 
 static int afs_file_readpage(struct file *file, struct page *page);
-static int afs_file_invalidatepage(struct page *page, unsigned long offset);
+static void afs_file_invalidatepage(struct page *page, unsigned long offset);
 static int afs_file_releasepage(struct page *page, gfp_t gfp_flags);
 
 struct inode_operations afs_file_inode_operations = {
···
 /*
  * invalidate part or all of a page
  */
-static int afs_file_invalidatepage(struct page *page, unsigned long offset)
+static void afs_file_invalidatepage(struct page *page, unsigned long offset)
 {
 	int ret = 1;
 
···
 			if (!PageWriteback(page))
 				ret = page->mapping->a_ops->releasepage(page,
 									0);
+			/* possibly should BUG_ON(!ret); - neilb */
 		}
 	}
 
 	_leave(" = %d", ret);
-	return ret;
 } /* end afs_file_invalidatepage() */
 
 /*****************************************************************************/

fs/buffer.c

···
  * point.  Because the caller is about to free (and possibly reuse) those
  * blocks on-disk.
  */
-int block_invalidatepage(struct page *page, unsigned long offset)
+void block_invalidatepage(struct page *page, unsigned long offset)
 {
 	struct buffer_head *head, *bh, *next;
 	unsigned int curr_off = 0;
-	int ret = 1;
 
 	BUG_ON(!PageLocked(page));
 	if (!page_has_buffers(page))
···
 	 * so real IO is not possible anymore.
 	 */
 	if (offset == 0)
-		ret = try_to_release_page(page, 0);
+		try_to_release_page(page, 0);
 out:
-	return ret;
+	return;
 }
 EXPORT_SYMBOL(block_invalidatepage);
 
-int do_invalidatepage(struct page *page, unsigned long offset)
+void do_invalidatepage(struct page *page, unsigned long offset)
 {
-	int (*invalidatepage)(struct page *, unsigned long);
-	invalidatepage = page->mapping->a_ops->invalidatepage;
-	if (invalidatepage == NULL)
-		invalidatepage = block_invalidatepage;
-	return (*invalidatepage)(page, offset);
+	void (*invalidatepage)(struct page *, unsigned long);
+	invalidatepage = page->mapping->a_ops->invalidatepage ? :
+		block_invalidatepage;
+	(*invalidatepage)(page, offset);
 }
 
 /*

fs/ext3/inode.c

···
 	return mpage_readpages(mapping, pages, nr_pages, ext3_get_block);
 }
 
-static int ext3_invalidatepage(struct page *page, unsigned long offset)
+static void ext3_invalidatepage(struct page *page, unsigned long offset)
 {
 	journal_t *journal = EXT3_JOURNAL(page->mapping->host);
 
···
 	if (offset == 0)
 		ClearPageChecked(page);
 
-	return journal_invalidatepage(journal, page, offset);
+	journal_invalidatepage(journal, page, offset);
 }
 
 static int ext3_releasepage(struct page *page, gfp_t wait)

fs/jbd/transaction.c

···
 }
 
 /** 
- * int journal_invalidatepage() 
+ * void journal_invalidatepage()
  * @journal: journal to use for flush... 
  * @page:    page to flush
  * @offset:  length of page to invalidate.
  *
  * Reap page buffers containing data after offset in page.
  *
- * Return non-zero if the page's buffers were successfully reaped.
  */
-int journal_invalidatepage(journal_t *journal, 
+void journal_invalidatepage(journal_t *journal,
 		      struct page *page, 
 		      unsigned long offset)
 {
···
 	if (!PageLocked(page))
 		BUG();
 	if (!page_has_buffers(page))
-		return 1;
+		return;
 
 	/* We will potentially be playing with lists other than just the
 	 * data lists (especially for journaled data mode), so be
···
 	} while (bh != head);
 
 	if (!offset) {
-		if (!may_free || !try_to_free_buffers(page))
-			return 0;
-		J_ASSERT(!page_has_buffers(page));
+		if (may_free && try_to_free_buffers(page))
+			J_ASSERT(!page_has_buffers(page));
 	}
-	return 1;
 }
 
 /* 

fs/jfs/jfs_metapage.c

···
 	return 0;
 }
 
-static int metapage_invalidatepage(struct page *page, unsigned long offset)
+static void metapage_invalidatepage(struct page *page, unsigned long offset)
 {
 	BUG_ON(offset);
 
-	if (PageWriteback(page))
-		return 0;
+	BUG_ON(PageWriteback(page));
 
-	return metapage_releasepage(page, 0);
+	metapage_releasepage(page, 0);
 }
 
 struct address_space_operations jfs_metapage_aops = {

fs/nfs/file.c

···
 	return status;
 }
 
-static int nfs_invalidate_page(struct page *page, unsigned long offset)
+static void nfs_invalidate_page(struct page *page, unsigned long offset)
 {
 	/* FIXME: we really should cancel any unstarted writes on this page */
-	return 1;
 }
 
 static int nfs_release_page(struct page *page, gfp_t gfp)

fs/reiserfs/inode.c

···
 }
 
 /* clm -- taken from fs/buffer.c:block_invalidate_page */
-static int reiserfs_invalidatepage(struct page *page, unsigned long offset)
+static void reiserfs_invalidatepage(struct page *page, unsigned long offset)
 {
 	struct buffer_head *head, *bh, *next;
 	struct inode *inode = page->mapping->host;
···
 	 * The get_block cached value has been unconditionally invalidated,
 	 * so real IO is not possible anymore.
 	 */
-	if (!offset && ret)
+	if (!offset && ret) {
 		ret = try_to_release_page(page, 0);
+		/* maybe should BUG_ON(!ret); - neilb */
+	}
       out:
-	return ret;
+	return;
 }
 
 static int reiserfs_set_page_dirty(struct page *page)

fs/xfs/linux-2.6/xfs_aops.c

···
 	return mpage_readpages(mapping, pages, nr_pages, xfs_get_block);
 }
 
-STATIC int
+STATIC void
 xfs_vm_invalidatepage(
 	struct page		*page,
 	unsigned long		offset)
 {
 	xfs_page_trace(XFS_INVALIDPAGE_ENTER,
 			page->mapping->host, page, offset);
-	return block_invalidatepage(page, offset);
+	block_invalidatepage(page, offset);
 }
 
 struct address_space_operations xfs_address_space_operations = {

include/linux/buffer_head.h

···
  * address_spaces.
  */
 int try_to_release_page(struct page * page, gfp_t gfp_mask);
-int block_invalidatepage(struct page *page, unsigned long offset);
-int do_invalidatepage(struct page *page, unsigned long offset);
+void block_invalidatepage(struct page *page, unsigned long offset);
+void do_invalidatepage(struct page *page, unsigned long offset);
 int block_write_full_page(struct page *page, get_block_t *get_block,
 				struct writeback_control *wbc);
 int block_read_full_page(struct page*, get_block_t*);

include/linux/fs.h

···
 	int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
 	/* Unfortunately this kludge is needed for FIBMAP. Don't use it */
 	sector_t (*bmap)(struct address_space *, sector_t);
-	int (*invalidatepage) (struct page *, unsigned long);
+	void (*invalidatepage) (struct page *, unsigned long);
 	int (*releasepage) (struct page *, gfp_t);
 	ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov,
 			loff_t offset, unsigned long nr_segs);

include/linux/jbd.h

···
 extern void	 journal_release_buffer (handle_t *, struct buffer_head *);
 extern int	 journal_forget (handle_t *, struct buffer_head *);
 extern void	 journal_sync_buffer (struct buffer_head *);
-extern int	 journal_invalidatepage(journal_t *,
+extern void	 journal_invalidatepage(journal_t *,
 				struct page *, unsigned long);
 extern int	 journal_try_to_free_buffers(journal_t *, struct page *, gfp_t);
 extern int	 journal_stop(handle_t *);