Commit f143f1ea authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

mm/writeback: Add folio_start_writeback() 



Rename set_page_writeback() to folio_start_writeback() to match
folio_end_writeback().  Do not bother with wrappers that return void;
callers are perfectly capable of ignoring return values.

Add wrappers for set_page_writeback(), set_page_writeback_keepwrite() and
test_set_page_writeback() for compatibililty with existing filesystems.
The main advantage of this patch is getting the statistics right,
although it does eliminate a couple of calls to compound_head().

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDavid Howells <dhowells@redhat.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
parent 269ccca3

include/linux/page-flags.h

+10 −9
Original line number Diff line number Diff line
@@ -657,21 +657,22 @@ static __always_inline void SetPageUptodate(struct page *page) 


CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)



int __test_set_page_writeback(struct page *page, bool keep_write);

bool __folio_start_writeback(struct folio *folio, bool keep_write);

bool set_page_writeback(struct page *page);



#define test_set_page_writeback(page)			\

	__test_set_page_writeback(page, false)

#define test_set_page_writeback_keepwrite(page)	\

	__test_set_page_writeback(page, true)

#define folio_start_writeback(folio)			\

	__folio_start_writeback(folio, false)

#define folio_start_writeback_keepwrite(folio)	\

	__folio_start_writeback(folio, true)



static inline void set_page_writeback(struct page *page)

static inline void set_page_writeback_keepwrite(struct page *page)

{

	test_set_page_writeback(page);

	folio_start_writeback_keepwrite(page_folio(page));

}



static inline void set_page_writeback_keepwrite(struct page *page)

static inline bool test_set_page_writeback(struct page *page)

{

	test_set_page_writeback_keepwrite(page);

	return set_page_writeback(page);

}



__PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)

mm/folio-compat.c

+6 −0
Original line number Diff line number Diff line
@@ -71,3 +71,9 @@ void migrate_page_copy(struct page *newpage, struct page *page) 
}

EXPORT_SYMBOL(migrate_page_copy);

#endif



bool set_page_writeback(struct page *page)

{

	return folio_start_writeback(page_folio(page));

}

EXPORT_SYMBOL(set_page_writeback);

mm/page-writeback.c

+20 −19
Original line number Diff line number Diff line
@@ -2811,21 +2811,23 @@ bool __folio_end_writeback(struct folio *folio) 
	return ret;

}



int __test_set_page_writeback(struct page *page, bool keep_write)

bool __folio_start_writeback(struct folio *folio, bool keep_write)

{

	struct address_space *mapping = page_mapping(page);

	int ret, access_ret;

	long nr = folio_nr_pages(folio);

	struct address_space *mapping = folio_mapping(folio);

	bool ret;

	int access_ret;



	lock_page_memcg(page);

	folio_memcg_lock(folio);

	if (mapping && mapping_use_writeback_tags(mapping)) {

		XA_STATE(xas, &mapping->i_pages, page_index(page));

		XA_STATE(xas, &mapping->i_pages, folio_index(folio));

		struct inode *inode = mapping->host;

		struct backing_dev_info *bdi = inode_to_bdi(inode);

		unsigned long flags;



		xas_lock_irqsave(&xas, flags);

		xas_load(&xas);

		ret = TestSetPageWriteback(page);

		ret = folio_test_set_writeback(folio);

		if (!ret) {

			bool on_wblist;
@@ -2836,43 +2838,42 @@ int __test_set_page_writeback(struct page *page, bool keep_write) 
			if (bdi->capabilities & BDI_CAP_WRITEBACK_ACCT) {

				struct bdi_writeback *wb = inode_to_wb(inode);



				inc_wb_stat(wb, WB_WRITEBACK);

				wb_stat_mod(wb, WB_WRITEBACK, nr);

				if (!on_wblist)

					wb_inode_writeback_start(wb);

			}



			/*

			 * We can come through here when swapping anonymous

			 * pages, so we don't necessarily have an inode to track

			 * for sync.

			 * We can come through here when swapping

			 * anonymous folios, so we don't necessarily

			 * have an inode to track for sync.

			 */

			if (mapping->host && !on_wblist)

				sb_mark_inode_writeback(mapping->host);

		}

		if (!PageDirty(page))

		if (!folio_test_dirty(folio))

			xas_clear_mark(&xas, PAGECACHE_TAG_DIRTY);

		if (!keep_write)

			xas_clear_mark(&xas, PAGECACHE_TAG_TOWRITE);

		xas_unlock_irqrestore(&xas, flags);

	} else {

		ret = TestSetPageWriteback(page);

		ret = folio_test_set_writeback(folio);

	}

	if (!ret) {

		inc_lruvec_page_state(page, NR_WRITEBACK);

		inc_zone_page_state(page, NR_ZONE_WRITE_PENDING);

		lruvec_stat_mod_folio(folio, NR_WRITEBACK, nr);

		zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, nr);

	}

	unlock_page_memcg(page);

	access_ret = arch_make_page_accessible(page);

	folio_memcg_unlock(folio);

	access_ret = arch_make_folio_accessible(folio);

	/*

	 * If writeback has been triggered on a page that cannot be made

	 * accessible, it is too late to recover here.

	 */

	VM_BUG_ON_PAGE(access_ret != 0, page);

	VM_BUG_ON_FOLIO(access_ret != 0, folio);



	return ret;



}

EXPORT_SYMBOL(__test_set_page_writeback);

EXPORT_SYMBOL(__folio_start_writeback);



/**

 * folio_wait_writeback - Wait for a folio to finish writeback.