+ include-linux-pagemaph-introduce-attach-detach_page_private.patch added to -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: include/linux/pagemap.h: introduce attach/detach_page_private
has been added to the -mm tree.  Its filename is
     include-linux-pagemaph-introduce-attach-detach_page_private.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/include-linux-pagemaph-introduce-attach-detach_page_private.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/include-linux-pagemaph-introduce-attach-detach_page_private.patch

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------------------------------------------------------
From: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
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@cloud.ionos.com
Link: http://lkml.kernel.org/r/20200517214718.468-2-guoqing.jiang@cloud.ionos.com
Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Suggested-by: Matthew Wilcox <willy@infradead.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: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Chao Yu <chao@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Anton Altaparmakov <anton@tuxera.com>
Cc: Mike Marshall <hubcap@omnibond.com>
Cc: Martin Brandenburg <martin@omnibond.com>
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>
Cc: Chao Yu <yuchao0@huawei.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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
_

Patches currently in -mm which might be from guoqing.jiang@cloud.ionos.com are

include-linux-pagemaph-introduce-attach-detach_page_private.patch
md-remove-__clear_page_buffers-and-use-attach-detach_page_private.patch
btrfs-use-attach-detach_page_private.patch
fs-bufferc-use-attach-detach_page_private.patch
f2fs-use-attach-detach_page_private.patch
iomap-use-attach-detach_page_private.patch
ntfs-replace-attach_page_buffers-with-attach_page_private.patch
orangefs-use-attach-detach_page_private.patch
buffer_headh-remove-attach_page_buffers.patch
mm-migratec-call-detach_page_private-to-cleanup-code.patch