Messages in this thread Patch in this message | | | From | Guoqing Jiang <> | Subject | [PATCH 01/10] include/linux/pagemap.h: introduce attach/detach_page_private | Date | Sun, 17 May 2020 23:47:09 +0200 |
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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.
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> Cc: Song Liu <song@kernel.org> Cc: linux-raid@vger.kernel.org Cc: Chris Mason <clm@fb.com> Cc: Josef Bacik <josef@toxicpanda.com> Cc: David Sterba <dsterba@suse.com> Cc: linux-btrfs@vger.kernel.org Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Jaegeuk Kim <jaegeuk@kernel.org> Cc: Chao Yu <chao@kernel.org> Cc: linux-f2fs-devel@lists.sourceforge.net Cc: Christoph Hellwig <hch@infradead.org> Cc: linux-xfs@vger.kernel.org Cc: Anton Altaparmakov <anton@tuxera.com> Cc: linux-ntfs-dev@lists.sourceforge.net Cc: Mike Marshall <hubcap@omnibond.com> Cc: Martin Brandenburg <martin@omnibond.com> Cc: devel@lists.orangefs.org Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Roman Gushchin <guro@fb.com> Cc: Andreas Dilger <adilger@dilger.ca> Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com> --- No change since RFC V3.
RFC V2 -> RFC V3: 1. rename clear_page_private to detach_page_private. 2. updated the comments for the two functions.
RFC -> RFC V2: Address the comments from Christoph Hellwig 1. change function names to attach/clear_page_private and add comments. 2. change the return type of attach_page_private.
include/linux/pagemap.h | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index c6348c50136f..8e085713150c 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -208,6 +208,43 @@ static inline int page_cache_add_speculative(struct page *page, int count) 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 -- 2.17.1
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