mm: move page dirtying prototypes from mm.h

These functions implement the address_space ->set_page_dirty operation and
should live in pagemap.h, not mm.h so that the rest of the kernel doesn't
get funny ideas about calling them directly.

Link: https://lkml.kernel.org/r/20210615162342.1669332-7-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/fuse/dax.c

@@ -9,6 +9,7 @@
 #include <linux/delay.h>
 #include <linux/dax.h>
 #include <linux/uio.h>
+#include <linux/pagemap.h>
 #include <linux/pfn_t.h>
 #include <linux/iomap.h>
 #include <linux/interval_tree.h>

fs/zonefs/super.c

@@ -5,7 +5,7 @@
  * Copyright (C) 2019 Western Digital Corporation or its affiliates.
  */
 #include <linux/module.h>
-#include <linux/fs.h>
+#include <linux/pagemap.h>
 #include <linux/magic.h>
 #include <linux/iomap.h>
 #include <linux/init.h>

include/linux/mm.h

@@ -1850,9 +1850,6 @@ extern int try_to_release_page(struct page * page, gfp_t gfp_mask);
 extern void do_invalidatepage(struct page *page, unsigned int offset,
 			      unsigned int length);
 
-void __set_page_dirty(struct page *, struct address_space *, int warn);
-int __set_page_dirty_nobuffers(struct page *page);
-int __set_page_dirty_no_writeback(struct page *page);
 int redirty_page_for_writepage(struct writeback_control *wbc,
 				struct page *page);
 void account_page_cleaned(struct page *page, struct address_space *mapping,

include/linux/pagemap.h

@@ -702,6 +702,10 @@ int wait_on_page_writeback_killable(struct page *page);
 extern void end_page_writeback(struct page *page);
 void wait_for_stable_page(struct page *page);
 
+void __set_page_dirty(struct page *, struct address_space *, int warn);
+int __set_page_dirty_nobuffers(struct page *page);
+int __set_page_dirty_no_writeback(struct page *page);
+
 void page_endio(struct page *page, bool is_write, int err);
 
 /**