From: Larry Woodman on
On Wed, 2010-05-26 at 11:49 -0400, Rik van Riel wrote:
> From: Jeff Moyer <jmoyer(a)redhat.com>
>
> I/O errors can happen due to temporary failures, like multipath
> errors or losing network contact with the iSCSI server. Because
> of that, the VM will retry readpage on the page.
>
> However, do_generic_file_read does not clear PG_error. This
> causes the system to be unable to actually use the data in the
> page cache page, even if the subsequent readpage completes
> successfully!
>
> The function filemap_fault has had a ClearPageError before
> readpage forever. This patch simply adds the same to
> do_generic_file_read.
>
> Signed-off-by: Rik van Riel <riel(a)redhat.com>
> Signed-off-by: Jeff Moyer <jmoyer(a)redhat.com>
> ---
> mm/filemap.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> Index: linux-2.6.34/mm/filemap.c
> ===================================================================
> --- linux-2.6.34.orig/mm/filemap.c
> +++ linux-2.6.34/mm/filemap.c
> @@ -1106,6 +1106,12 @@ page_not_up_to_date_locked:
> }
>
> readpage:
> + /*
> + * A previous I/O error may have been due to temporary
> + * failures, eg. multipath errors.
> + * PG_error will be set again if readpage fails.
> + */
> + ClearPageError(page);
> /* Start the actual read. The read will unlock the page. */
> error = mapping->a_ops->readpage(filp, page);
>
Acked-by: Larry Woodman <lwoodman(a)redhat.com>

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