[PATCH 06/13] mm: factor out a filemap_find_get_pages helper

[Christoph Hellwig <hch@xxxxxx>]

Factor out a helper to lookup a range of contiguous pages from
generic_file_buffered_read_get_pages.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 mm/filemap.c | 47 +++++++++++++++++++++++++++--------------------
 1 file changed, 27 insertions(+), 20 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 9e1cc18afe1134..0af7ddaa0fe7ba 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2323,39 +2323,46 @@ static int filemap_new_page(struct kiocb *iocb, struct iov_iter *iter,
 	return filemap_readpage(iocb, *page);
 }
 
+static int filemap_find_get_pages(struct kiocb *iocb, struct iov_iter *iter,
+		struct page **pages, unsigned int nr)
+{
+	struct address_space *mapping = iocb->ki_filp->f_mapping;
+	pgoff_t index = iocb->ki_pos >> PAGE_SHIFT;
+	pgoff_t last_index = (iocb->ki_pos + iter->count + PAGE_SIZE - 1) >>
+			PAGE_SHIFT;
+	int nr_pages;
+
+	nr = min_t(unsigned long, last_index - index, nr);
+	nr_pages = find_get_pages_contig(mapping, index, nr, pages);
+	if (nr_pages)
+		return nr_pages;
+
+	if (iocb->ki_flags & IOCB_NOIO)
+		return -EAGAIN;
+	page_cache_sync_readahead(mapping, &iocb->ki_filp->f_ra, iocb->ki_filp,
+			index, last_index - index);
+	return find_get_pages_contig(mapping, index, nr, pages);
+}
+
 static int generic_file_buffered_read_get_pages(struct kiocb *iocb,
 						struct iov_iter *iter,
 						struct page **pages,
 						unsigned int nr)
 {
-	struct file *filp = iocb->ki_filp;
-	struct address_space *mapping = filp->f_mapping;
-	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;
 	int i, j, nr_got, err = 0;
 
-	nr = min_t(unsigned long, last_index - index, nr);
 find_page:
 	if (fatal_signal_pending(current))
 		return -EINTR;
 
-	nr_got = find_get_pages_contig(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 = filemap_find_get_pages(iocb, iter, pages, nr);
+	if (!nr_got) {
+		err = filemap_new_page(iocb, iter, &pages[0]);
+		if (!err)
+			nr_got = 1;
+	}
 
-	nr_got = find_get_pages_contig(mapping, index, nr, pages);
-	if (nr_got)
-		goto got_pages;
-	err = filemap_new_page(iocb, iter, &pages[0]);
-	if (!err)
-		nr_got = 1;
-got_pages:
 	for (i = 0; i < nr_got; i++) {
 		err = filemap_make_page_uptodate(iocb, iter, pages[i],
 				index + i, i == 0);
-- 
2.28.0