Re: [PATCH v4 21/27] mm: clean up error handling in write_one_page

From: Jan Kara
Date: Mon May 15 2017 - 08:01:33 EST


On Tue 09-05-17 11:49:24, Jeff Layton wrote:
> Don't try to check PageError since that's potentially racy and not
> necessarily going to be set after writepage errors out.
>
> Instead, sample the mapping error early on, and use that value to tell
> us whether we got a writeback error since then.
>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>

Looks good to me. You can add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

Honza

> ---
> mm/page-writeback.c | 11 +++++------
> 1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index de0dbf12e2c1..1643456881b4 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -2373,11 +2373,12 @@ int do_writepages(struct address_space *mapping, struct writeback_control *wbc)
> int write_one_page(struct page *page)
> {
> struct address_space *mapping = page->mapping;
> - int ret = 0;
> + int ret = 0, ret2;
> struct writeback_control wbc = {
> .sync_mode = WB_SYNC_ALL,
> .nr_to_write = 1,
> };
> + errseq_t since = filemap_sample_wb_error(mapping);
>
> BUG_ON(!PageLocked(page));
>
> @@ -2386,16 +2387,14 @@ int write_one_page(struct page *page)
> if (clear_page_dirty_for_io(page)) {
> get_page(page);
> ret = mapping->a_ops->writepage(page, &wbc);
> - if (ret == 0) {
> + if (ret == 0)
> wait_on_page_writeback(page);
> - if (PageError(page))
> - ret = -EIO;
> - }
> put_page(page);
> } else {
> unlock_page(page);
> }
> - return ret;
> + ret2 = filemap_check_wb_error(mapping, since);
> + return ret ? : ret2;
> }
> EXPORT_SYMBOL(write_one_page);
>
> --
> 2.9.3
>
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR