mm/filemap: restructure filemap_get_pages

Remove the got_pages label, remove indentation, rename find_page to retry,
simplify error handling.

Link: https://lkml.kernel.org/r/20210122160140.223228-16-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 f8181beded3814b2023a27a2be49a2b9f58539ec..3311b2af9061cd1d9d6083167c073a482d028c2f 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2349,70 +2349,55 @@ 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;
+       struct page *page;
        int err = 0;
 
        last_index = DIV_ROUND_UP(iocb->ki_pos + iter->count, PAGE_SIZE);
-find_page:
+retry:
        if (fatal_signal_pending(current))
                return -EINTR;
 
-       filemap_get_read_batch(mapping, index, last_index, pvec);
-       if (pvec->nr)
-               goto got_pages;
-
-       if (iocb->ki_flags & IOCB_NOIO)
-               return -EAGAIN;
-
-       page_cache_sync_readahead(mapping, ra, filp, index, last_index - index);
-
        filemap_get_read_batch(mapping, index, last_index, pvec);
+       if (!pagevec_count(pvec)) {
+               if (iocb->ki_flags & IOCB_NOIO)
+                       return -EAGAIN;
+               page_cache_sync_readahead(mapping, ra, filp, index,
+                               last_index - index);
+               filemap_get_read_batch(mapping, index, last_index, pvec);
+       }
        if (!pagevec_count(pvec)) {
                if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))
                        return -EAGAIN;
                err = filemap_create_page(filp, mapping,
                                iocb->ki_pos >> PAGE_SHIFT, pvec);
                if (err == AOP_TRUNCATED_PAGE)
-                       goto find_page;
+                       goto retry;
                return err;
        }
-got_pages:
-       {
-               struct page *page = pvec->pages[pvec->nr - 1];
-
-               if (PageReadahead(page)) {
-                       err = filemap_readahead(iocb, filp, mapping, page,
-                                       last_index);
-                       if (err) {
-                               put_page(page);
-                               pvec->nr--;
-                               goto err;
-                       }
-               }
 
-               if (!PageUptodate(page)) {
-                       if ((iocb->ki_flags & IOCB_WAITQ) &&
-                           pagevec_count(pvec) > 1)
-                               iocb->ki_flags |= IOCB_NOWAIT;
-                       err = filemap_update_page(iocb, mapping, iter, page);
-                       if (err) {
-                               if (err < 0)
-                                       put_page(page);
-                               pvec->nr--;
-                       }
-               }
+       page = pvec->pages[pagevec_count(pvec) - 1];
+       if (PageReadahead(page)) {
+               err = filemap_readahead(iocb, filp, mapping, page, last_index);
+               if (err)
+                       goto err;
+       }
+       if (!PageUptodate(page)) {
+               if ((iocb->ki_flags & IOCB_WAITQ) && pagevec_count(pvec) > 1)
+                       iocb->ki_flags |= IOCB_NOWAIT;
+               err = filemap_update_page(iocb, mapping, iter, page);
+               if (err)
+                       goto err;
        }
 
+       return 0;
 err:
-       if (likely(pvec->nr))
+       if (err < 0)
+               put_page(page);
+       if (likely(--pvec->nr))
                return 0;
        if (err == AOP_TRUNCATED_PAGE)
-               goto find_page;
-       if (err)
-               return err;
-       /*
-        * No pages and no error means we raced and should retry:
-        */
-       goto find_page;
+               goto retry;
+       return err;
 }
 
 /**