On 2022/06/03 2:22, Andrew Morton wrote:
On Thu, 2 Jun 2022 16:21:29 +0800 Yu Kuai <yukuai3@xxxxxxxxxx> wrote:
In filemap_read(), 'ra->prev_pos' is set to 'iocb->ki_pos + copied',
while it should be 'iocb->ki_ops'. For consequence,
folio_mark_accessed() will not be called for 'fbatch.folios[0]' since
'iocb->ki_pos' is always equal to 'ra->prev_pos'.
...
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2728,10 +2728,11 @@ ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *iter,
flush_dcache_folio(folio);
copied = copy_folio_to_iter(folio, offset, bytes, iter);
-
- already_read += copied;
- iocb->ki_pos += copied;
- ra->prev_pos = iocb->ki_pos;
+ if (copied) {
+ ra->prev_pos = iocb->ki_pos;
+ already_read += copied;
+ iocb->ki_pos += copied;
+ }
if (copied < bytes) {
error = -EFAULT;
It seems tidier, but does it matter? If copied==0 we're going to break
out and return -EFAULT anyway?
Hi,
Please notice that I set 'prev_ops' to 'ki_pos' first here, instead of
'ki_pos + copied'.
Thanks,
Kuai
.
