Re: [PATCH v2 6/9] mm: set mapping error when launder_pages fails

[NeilBrown]

On Thu, Mar 09 2017, Trond Myklebust wrote:

> On Wed, 2017-03-08 at 11:29 -0500, Jeff Layton wrote:
>> If launder_page fails, then we hit a problem writing back some inode
>> data. Ensure that we communicate that fact in a subsequent fsync
>> since
>> another task could still have it open for write.
>> 
>> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
>> ---
>> Âmm/truncate.c | 6 +++++-
>> Â1 file changed, 5 insertions(+), 1 deletion(-)
>> 
>> diff --git a/mm/truncate.c b/mm/truncate.c
>> index 6263affdef88..29ae420a5bf9 100644
>> --- a/mm/truncate.c
>> +++ b/mm/truncate.c
>> @@ -594,11 +594,15 @@ invalidate_complete_page2(struct address_space
>> *mapping, struct page *page)
>> Â
>> Âstatic int do_launder_page(struct address_space *mapping, struct
>> page *page)
>> Â{
>> +	int ret;
>> +
>> Â	if (!PageDirty(page))
>> Â		return 0;
>> Â	if (page->mapping != mapping || mapping->a_ops->launder_page 
>> == NULL)
>> Â		return 0;
>> -	return mapping->a_ops->launder_page(page);
>> +	ret = mapping->a_ops->launder_page(page);
>> +	mapping_set_error(mapping, ret);
>> +	return ret;
>> Â}
>> Â
>> Â/**
>
> No. At that layer, you don't know that this is a page error. In the NFS
> case, it could, for instance, just as well be a fatal signal.
>

In that case, would 'ret' be ERESTARTSYS or EAGAIN or similar?
Should mapping_set_error() ignore those?

Thanks,
NeilBrown

> -- 
> Trond Myklebust
> Linux NFS client maintainer, PrimaryData
> trond.myklebust@xxxxxxxxxxxxxxx

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