mm/filemap: split filemap_readahead out of filemap_get_pages

This simplifies the error handling.

Link: https://lkml.kernel.org/r/20210122160140.223228-15-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Kent Overstreet <kent.overstreet@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/filemap.c b/mm/filemap.c
index 1eaafc9..f8181be 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2330,6 +2330,17 @@ error:
        return error;
 }
 
+static int filemap_readahead(struct kiocb *iocb, struct file *file,
+               struct address_space *mapping, struct page *page,
+               pgoff_t last_index)
+{
+       if (iocb->ki_flags & IOCB_NOIO)
+               return -EAGAIN;
+       page_cache_async_readahead(mapping, &file->f_ra, file, page,
+                       page->index, last_index - page->index);
+       return 0;
+}
+
 static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
                struct pagevec *pvec)
 {
@@ -2367,17 +2378,15 @@ find_page:
 got_pages:
        {
                struct page *page = pvec->pages[pvec->nr - 1];
-               pgoff_t pg_index = page->index;
 
                if (PageReadahead(page)) {
-                       if (iocb->ki_flags & IOCB_NOIO) {
+                       err = filemap_readahead(iocb, filp, mapping, page,
+                                       last_index);
+                       if (err) {
                                put_page(page);
                                pvec->nr--;
-                               err = -EAGAIN;
                                goto err;
                        }
-                       page_cache_async_readahead(mapping, ra, filp, page,
-                                       pg_index, last_index - pg_index);
                }
 
                if (!PageUptodate(page)) {