btrfs: Switch from using the private_2 flag to owner_2

We are close to removing the private_2 flag, so switch btrfs to using
owner_2 for its ordered flag.  This is mostly used by buffer head
filesystems, so btrfs can use it because it doesn't use buffer heads.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20241002040111.1023018-5-willy@infradead.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: Matthew Wilcox (Oracle)

fs/btrfs/ctree.h

@@ -744,16 +744,11 @@ const char *btrfs_super_csum_driver(u16 csum_type);
 size_t __attribute_const__ btrfs_get_num_csums(void);
 
 /*
- * We use page status Private2 to indicate there is an ordered extent with
+ * We use folio flag owner_2 to indicate there is an ordered extent with
  * unfinished IO.
- *
- * Rename the Private2 accessors to Ordered, to improve readability.
  */
-#define PageOrdered(page)		PagePrivate2(page)
-#define SetPageOrdered(page)		SetPagePrivate2(page)
-#define ClearPageOrdered(page)		ClearPagePrivate2(page)
-#define folio_test_ordered(folio)	folio_test_private_2(folio)
-#define folio_set_ordered(folio)	folio_set_private_2(folio)
-#define folio_clear_ordered(folio)	folio_clear_private_2(folio)
+#define folio_test_ordered(folio)	folio_test_owner_2(folio)
+#define folio_set_ordered(folio)	folio_set_owner_2(folio)
+#define folio_clear_ordered(folio)	folio_clear_owner_2(folio)
 
 #endif

fs/btrfs/inode.c

@@ -1513,7 +1513,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
 		 * (which the caller expects to stay locked), don't clear any
 		 * dirty bits and don't set any writeback bits
 		 *
-		 * Do set the Ordered (Private2) bit so we know this page was
+		 * Do set the Ordered flag so we know this page was
 		 * properly setup for writepage.
 		 */
 		page_ops = (keep_locked ? 0 : PAGE_UNLOCK);
@@ -7292,7 +7292,7 @@ static void btrfs_invalidate_folio(struct folio *folio, size_t offset,
 	 *
 	 * But already submitted bio can still be finished on this folio.
 	 * Furthermore, endio function won't skip folio which has Ordered
-	 * (Private2) already cleared, so it's possible for endio and
+	 * already cleared, so it's possible for endio and
 	 * invalidate_folio to do the same ordered extent accounting twice
 	 * on one folio.
 	 *
@@ -7358,7 +7358,7 @@ static void btrfs_invalidate_folio(struct folio *folio, size_t offset,
 		range_len = range_end + 1 - cur;
 		if (!btrfs_folio_test_ordered(fs_info, folio, cur, range_len)) {
 			/*
-			 * If Ordered (Private2) is cleared, it means endio has
+			 * If Ordered is cleared, it means endio has
 			 * already been executed for the range.
 			 * We can't delete the extent states as
 			 * btrfs_finish_ordered_io() may still use some of them.
@@ -7431,7 +7431,7 @@ static void btrfs_invalidate_folio(struct folio *folio, size_t offset,
 	}
 	/*
 	 * We have iterated through all ordered extents of the page, the page
-	 * should not have Ordered (Private2) anymore, or the above iteration
+	 * should not have Ordered anymore, or the above iteration
 	 * did something wrong.
 	 */
 	ASSERT(!folio_test_ordered(folio));

fs/btrfs/ordered-data.c

@@ -346,10 +346,10 @@ static bool can_finish_ordered_extent(struct btrfs_ordered_extent *ordered,
 		ASSERT(file_offset + len <= folio_pos(folio) + folio_size(folio));
 
 		/*
-		 * Ordered (Private2) bit indicates whether we still have
+		 * Ordered flag indicates whether we still have
 		 * pending io unfinished for the ordered extent.
 		 *
-		 * If there's no such bit, we need to skip to next range.
+		 * If it's not set, we need to skip to next range.
 		 */
 		if (!btrfs_folio_test_ordered(fs_info, folio, file_offset, len))
 			return false;