[RFC PATCH 1/9] include/linux/pagemap.h: introduce set/clear_fs_page_private

Guoqing Jiang
2020-04-26T21:50:31Z

The logic in attach_page_buffers and __clear_page_buffers are quite
paired, but

1. they are located in different files.

2. attach_page_buffers is implemented in buffer_head.h, so it could be
used by other files. But __clear_page_buffers is static function in
buffer.c and other potential users can't call the function, md-bitmap
even copied the function.

So, introduce the new set/clear_fs_page_private to replace them since
they are mostly used in fs layer. With the new pair of function, we will
remove the usage of attach_page_buffers and __clear_page_buffers in
next patches.

Suggested-by: Matthew Wilcox <willy@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
---
include/linux/pagemap.h | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index a8f7bd8ea1c6..2a165ea647fe 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -205,6 +205,28 @@ static inline int page_cache_add_speculative(struct page *page, int count)
return __page_cache_add_speculative(page, count);
}

+static inline void *set_fs_page_private(struct page *page, void *data)
+{
+ get_page(page);
+ set_page_private(page, (unsigned long)data);
+ SetPagePrivate(page);
+
+ return data;
+}
+
+static inline void *clear_fs_page_private(struct page *page)
+{
+ void *data = (void *)page_private(page);
+
+ if (!PagePrivate(page))
+ return NULL;
+ ClearPagePrivate(page);
+ set_page_private(page, 0);
+ put_page(page);
+
+ return data;
+}
+
#ifdef CONFIG_NUMA
extern struct page *__page_cache_alloc(gfp_t gfp);
#else
--
2.17.1