[RFC PATCH V3 06/10] iomap: use attach/detach_page_private

[Guoqing Jiang]

Since the new pair function is introduced, we can call them to clean the
code in iomap.

Cc: Christoph Hellwig <h...@infradead.org>
Cc: "Darrick J. Wong" <darrick.w...@oracle.com>
Cc: linux-...@vger.kernel.org
Signed-off-by: Guoqing Jiang <guoqing.ji...@cloud.ionos.com>
---
RFC V2 -> RFC V3
1. rename clear_page_private to detach_page_private.

RFC -> RFC V2
1. change the name of new functions to attach/clear_page_private.
2. call attach_page_private(newpage, clear_page_private(page)) to
   cleanup code further as suggested by Matthew Wilcox.
3. don't return attach_page_private in iomap_page_create per the
   comment from Christoph Hellwig.

 fs/iomap/buffered-io.c | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 89e21961d1ad..e3031007b4ae 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -59,24 +59,19 @@ iomap_page_create(struct inode *inode, struct page *page)
         * migrate_page_move_mapping() assumes that pages with private data have
         * their count elevated by 1.
         */
-       get_page(page);
-       set_page_private(page, (unsigned long)iop);
-       SetPagePrivate(page);
+       attach_page_private(page, iop);
        return iop;
 }
 
 static void
 iomap_page_release(struct page *page)
 {
-       struct iomap_page *iop = to_iomap_page(page);
+       struct iomap_page *iop = detach_page_private(page);
 
        if (!iop)
                return;
        WARN_ON_ONCE(atomic_read(&iop->read_count));
        WARN_ON_ONCE(atomic_read(&iop->write_count));
-       ClearPagePrivate(page);
-       set_page_private(page, 0);
-       put_page(page);
        kfree(iop);
 }
 
@@ -554,14 +549,8 @@ iomap_migrate_page(struct address_space *mapping, struct 
page *newpage,
        if (ret != MIGRATEPAGE_SUCCESS)
                return ret;
 
-       if (page_has_private(page)) {
-               ClearPagePrivate(page);
-               get_page(newpage);
-               set_page_private(newpage, page_private(page));
-               set_page_private(page, 0);
-               put_page(page);
-               SetPagePrivate(newpage);
-       }
+       if (page_has_private(page))
+               attach_page_private(newpage, detach_page_private(page));
 
        if (mode != MIGRATE_SYNC_NO_COPY)
                migrate_page_copy(newpage, page);
-- 
2.17.1