[PATCH 06/17] mm/filemap: Don't call ->readpage if IOCB_WAITQ is set

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

The readpage operation can block in many (most?) filesystems, so we
should punt to a work queue instead of calling it.  This was the last
caller of lock_page_async(), so remove it.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/filemap.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 7a4101ceb106..5bafd2dc830c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2152,16 +2152,6 @@ static void shrink_readahead_size_eio(struct file_ra_state *ra)
 	ra->ra_pages /= 4;
 }
 
-static int lock_page_for_iocb(struct kiocb *iocb, struct page *page)
-{
-	if (iocb->ki_flags & IOCB_WAITQ)
-		return lock_page_async(page, iocb->ki_waitq);
-	else if (iocb->ki_flags & IOCB_NOWAIT)
-		return trylock_page(page) ? 0 : -EAGAIN;
-	else
-		return lock_page_killable(page);
-}
-
 static unsigned mapping_get_read_thps(struct address_space *mapping,
 		pgoff_t index, unsigned int nr_pages, struct page **pages)
 {
@@ -2210,7 +2200,7 @@ static struct page *filemap_read_page(struct kiocb *iocb, struct file *filp,
 	struct file_ra_state *ra = &filp->f_ra;
 	int error;
 
-	if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT)) {
+	if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ)) {
 		unlock_page(page);
 		put_page(page);
 		return ERR_PTR(-EAGAIN);
@@ -2231,7 +2221,7 @@ static struct page *filemap_read_page(struct kiocb *iocb, struct file *filp,
 	}
 
 	if (!PageUptodate(page)) {
-		error = lock_page_for_iocb(iocb, page);
+		error = lock_page_killable(page);
 		if (unlikely(error)) {
 			put_page(page);
 			return ERR_PTR(error);
-- 
2.28.0