From: Guoqing Jiang <guoqing.jiang@xxxxxxxxxxxxxxx> Subject: include/linux/pagemap.h: introduce attach/detach_page_private Patch series "Introduce attach/detach_page_private to cleanup code". This patch (of 10): 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 attach/detach_page_private to replace them. With the new pair of function, we will remove the usage of attach_page_buffers and __clear_page_buffers in next patches. Thanks for suggestions about the function name from Alexander Viro, Andreas Grünbacher, Christoph Hellwig and Matthew Wilcox. Link: http://lkml.kernel.org/r/20200517214718.468-1-guoqing.jiang@xxxxxxxxxxxxxxx Link: http://lkml.kernel.org/r/20200517214718.468-2-guoqing.jiang@xxxxxxxxxxxxxxx Signed-off-by: Guoqing Jiang <guoqing.jiang@xxxxxxxxxxxxxxx> Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx> Cc: William Kucharski <william.kucharski@xxxxxxxxxx> Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Andreas Gruenbacher <agruenba@xxxxxxxxxx> Cc: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx> Cc: Yafang Shao <laoar.shao@xxxxxxxxx> Cc: Song Liu <song@xxxxxxxxxx> Cc: Chris Mason <clm@xxxxxx> Cc: Josef Bacik <josef@xxxxxxxxxxxxxx> Cc: David Sterba <dsterba@xxxxxxxx> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> Cc: Chao Yu <chao@xxxxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx> Cc: Anton Altaparmakov <anton@xxxxxxxxxx> Cc: Mike Marshall <hubcap@xxxxxxxxxxxx> Cc: Martin Brandenburg <martin@xxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Cc: Roman Gushchin <guro@xxxxxx> Cc: Andreas Dilger <adilger@xxxxxxxxx> Cc: Chao Yu <yuchao0@xxxxxxxxxx> Cc: Dave Chinner <david@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/pagemap.h | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) --- a/include/linux/pagemap.h~include-linux-pagemaph-introduce-attach-detach_page_private +++ a/include/linux/pagemap.h @@ -208,6 +208,43 @@ static inline int page_cache_add_specula return __page_cache_add_speculative(page, count); } +/** + * attach_page_private - Attach private data to a page. + * @page: Page to attach data to. + * @data: Data to attach to page. + * + * Attaching private data to a page increments the page's reference count. + * The data must be detached before the page will be freed. + */ +static inline void attach_page_private(struct page *page, void *data) +{ + get_page(page); + set_page_private(page, (unsigned long)data); + SetPagePrivate(page); +} + +/** + * detach_page_private - Detach private data from a page. + * @page: Page to detach data from. + * + * Removes the data that was previously attached to the page and decrements + * the refcount on the page. + * + * Return: Data that was attached to the page. + */ +static inline void *detach_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 _
