[PATCH 08/17] mm/filemap: Change filemap_create_page arguments

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

filemap_create_page() doesn't need the iocb or the iter.  It just needs
the file and the index.  Move the iocb flag checks to the caller.  We can
skip checking GFP_NOIO as that's checked a few lines earlier.  There's no
need to fall through to filemap_update_page() -- if filemap_create_page
couldn't update it, filemap_update_page will not be able to.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/filemap.c | 32 +++++++++++++++-----------------
 1 file changed, 15 insertions(+), 17 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 171da5c592fa..5527b239771c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2285,26 +2285,20 @@ static struct page *filemap_update_page(struct kiocb *iocb, struct file *filp,
 	return NULL;
 }
 
-static struct page *filemap_create_page(struct kiocb *iocb,
-		struct iov_iter *iter)
+static struct page *filemap_create_page(struct file *file,
+		struct address_space *mapping, pgoff_t index)
 {
-	struct file *filp = iocb->ki_filp;
-	struct address_space *mapping = filp->f_mapping;
-	pgoff_t index = iocb->ki_pos >> PAGE_SHIFT;
 	struct page *page;
 	int error;
 
-	if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ))
-		return ERR_PTR(-EAGAIN);
-
 	page = page_cache_alloc(mapping);
 	if (!page)
 		return ERR_PTR(-ENOMEM);
 
 	error = add_to_page_cache_lru(page, mapping, index,
-				      mapping_gfp_constraint(mapping, GFP_KERNEL));
+			mapping_gfp_constraint(mapping, GFP_KERNEL));
 	if (!error)
-		error = filemap_read_page(iocb->ki_filp, mapping, page);
+		error = filemap_read_page(file, mapping, page);
 	if (!error)
 		return page;
 	put_page(page);
@@ -2338,13 +2332,17 @@ static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
 	page_cache_sync_readahead(mapping, ra, filp, index, last_index - index);
 
 	nr_got = mapping_get_read_thps(mapping, index, nr, pages);
-	if (nr_got)
-		goto got_pages;
-
-	pages[0] = filemap_create_page(iocb, iter);
-	err = PTR_ERR_OR_ZERO(pages[0]);
-	if (!IS_ERR_OR_NULL(pages[0]))
-		nr_got = 1;
+	if (!nr_got) {
+		if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))
+			return -EAGAIN;
+		pages[0] = filemap_create_page(filp, mapping,
+				iocb->ki_pos >> PAGE_SHIFT);
+		if (!pages[0])
+			goto find_page;
+		if (IS_ERR(pages[0]))
+			return PTR_ERR(pages[0]);
+		return 1;
+	}
 got_pages:
 	if (nr_got > 0) {
 		struct page *page = pages[nr_got - 1];
-- 
2.28.0