[PATCH 14/17] mm/filemap: Restructure filemap_get_pages

["Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>]

Avoid a goto, and by the time we get to calling filemap_update_page(),
we definitely have at least one page.

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
 mm/filemap.c | 37 ++++++++++++++++---------------------
 1 file changed, 16 insertions(+), 21 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 0ae8305ccb97..f16b1eb03bca 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2343,6 +2343,7 @@ static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
 	struct file_ra_state *ra = &filp->f_ra;
 	pgoff_t index = iocb->ki_pos >> PAGE_SHIFT;
 	pgoff_t last_index = (iocb->ki_pos + iter->count + PAGE_SIZE-1) >> PAGE_SHIFT;
+	struct page *page;
 	int nr_got, err = 0;
 
 	nr = min_t(unsigned long, last_index - index, nr);
@@ -2351,15 +2352,13 @@ static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
 		return -EINTR;
 
 	nr_got = mapping_get_read_thps(mapping, index, nr, pages);
-	if (nr_got)
-		goto got_pages;
-
-	if (iocb->ki_flags & IOCB_NOIO)
-		return -EAGAIN;
-
-	page_cache_sync_readahead(mapping, ra, filp, index, last_index - index);
-
-	nr_got = mapping_get_read_thps(mapping, index, nr, pages);
+	if (!nr_got) {
+		if (iocb->ki_flags & IOCB_NOIO)
+			return -EAGAIN;
+		page_cache_sync_readahead(mapping, ra, filp, index,
+				last_index - index);
+		nr_got = mapping_get_read_thps(mapping, index, nr, pages);
+	}
 	if (!nr_got) {
 		if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))
 			return -EAGAIN;
@@ -2371,20 +2370,16 @@ static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
 			return PTR_ERR(pages[0]);
 		return 1;
 	}
-got_pages:
-	if (nr_got > 0) {
-		struct page *page = pages[nr_got - 1];
 
-		if (PageReadahead(page))
-			err = filemap_readahead(iocb, filp, mapping, page,
-					last_index);
-		if (!err && !PageUptodate(page))
-			err = filemap_update_page(iocb, mapping, iter, page,
-					nr_got == 1);
-		if (err)
-			nr_got--;
-	}
+	page = pages[nr_got - 1];
+	if (PageReadahead(page))
+		err = filemap_readahead(iocb, filp, mapping, page, last_index);
+	if (!err && !PageUptodate(page))
+		err = filemap_update_page(iocb, mapping, iter, page,
+				nr_got == 1);
 
+	if (err)
+		nr_got--;
 	if (likely(nr_got))
 		return nr_got;
 	if (err < 0)
-- 
2.28.0