Commit a49d0c50 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

mm/writeback: Add folio_wait_stable() 



Move wait_for_stable_page() into the folio compatibility file.
folio_wait_stable() avoids a call to compound_head() and is 14 bytes
smaller than wait_for_stable_page() was.  The net text size grows by 16
bytes as a result of this patch.  We can also remove thp_head() as this
was the last user.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Acked-by: default avatarJeff Layton <jlayton@kernel.org>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarWilliam Kucharski <william.kucharski@oracle.com>
Reviewed-by: default avatarDavid Howells <dhowells@redhat.com>
parent 490e016f

include/linux/huge_mm.h

+0 −15
Original line number Diff line number Diff line
@@ -250,15 +250,6 @@ static inline spinlock_t *pud_trans_huge_lock(pud_t *pud, 
		return NULL;

}



/**

 * thp_head - Head page of a transparent huge page.

 * @page: Any page (tail, head or regular) found in the page cache.

 */

static inline struct page *thp_head(struct page *page)

{

	return compound_head(page);

}



/**

 * thp_order - Order of a transparent huge page.

 * @page: Head page of a transparent huge page.
@@ -336,12 +327,6 @@ static inline struct list_head *page_deferred_list(struct page *page) 
#define HPAGE_PUD_MASK ({ BUILD_BUG(); 0; })

#define HPAGE_PUD_SIZE ({ BUILD_BUG(); 0; })



static inline struct page *thp_head(struct page *page)

{

	VM_BUG_ON_PGFLAGS(PageTail(page), page);

	return page;

}



static inline unsigned int thp_order(struct page *page)

{

	VM_BUG_ON_PGFLAGS(PageTail(page), page);

include/linux/pagemap.h

+1 −0
Original line number Diff line number Diff line
@@ -771,6 +771,7 @@ int folio_wait_writeback_killable(struct folio *folio); 
void end_page_writeback(struct page *page);

void folio_end_writeback(struct folio *folio);

void wait_for_stable_page(struct page *page);

void folio_wait_stable(struct folio *folio);



void __set_page_dirty(struct page *, struct address_space *, int warn);

int __set_page_dirty_nobuffers(struct page *page);

mm/folio-compat.c

+6 −0
Original line number Diff line number Diff line
@@ -29,3 +29,9 @@ void wait_on_page_writeback(struct page *page) 
	return folio_wait_writeback(page_folio(page));

}

EXPORT_SYMBOL_GPL(wait_on_page_writeback);



void wait_for_stable_page(struct page *page)

{

	return folio_wait_stable(page_folio(page));

}

EXPORT_SYMBOL_GPL(wait_for_stable_page);

mm/page-writeback.c

+14 −10
Original line number Diff line number Diff line
@@ -2920,17 +2920,21 @@ int folio_wait_writeback_killable(struct folio *folio) 
EXPORT_SYMBOL_GPL(folio_wait_writeback_killable);



/**

 * wait_for_stable_page() - wait for writeback to finish, if necessary.

 * @page:	The page to wait on.

 * folio_wait_stable() - wait for writeback to finish, if necessary.

 * @folio: The folio to wait on.

 *

 * This function determines if the given page is related to a backing device

 * that requires page contents to be held stable during writeback.  If so, then

 * it will wait for any pending writeback to complete.

 * This function determines if the given folio is related to a backing

 * device that requires folio contents to be held stable during writeback.

 * If so, then it will wait for any pending writeback to complete.

 *

 * Context: Sleeps.  Must be called in process context and with

 * no spinlocks held.  Caller should hold a reference on the folio.

 * If the folio is not locked, writeback may start again after writeback

 * has finished.

 */

void wait_for_stable_page(struct page *page)

void folio_wait_stable(struct folio *folio)

{

	page = thp_head(page);

	if (page->mapping->host->i_sb->s_iflags & SB_I_STABLE_WRITES)

		wait_on_page_writeback(page);

	if (folio->mapping->host->i_sb->s_iflags & SB_I_STABLE_WRITES)

		folio_wait_writeback(folio);

}

EXPORT_SYMBOL_GPL(wait_for_stable_page);
 
EXPORT_SYMBOL_GPL(folio_wait_stable);