Messages in this thread | | | Subject | Re: [PATCH -next] mm/filemap: fix that first page is not mark accessed in filemap_read() | From | Yu Kuai <> | Date | Mon, 6 Jun 2022 09:11:57 +0800 |
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On 2022/06/03 2:22, Andrew Morton wrote: > On Thu, 2 Jun 2022 16:21:29 +0800 Yu Kuai <yukuai3@huawei.com> 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 > . >
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