Re: [PATCH v2 01/16] CIFS: Fix async reading on reconnects

[Jeff Layton <jlayton-vpEMnDpepFuMZCB2o+C8xQ@public.gmane.org>]

On Fri, 27 Jun 2014 13:57:38 +0400
Pavel Shilovsky <pshilovsky-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org> wrote:

> If we get into read_into_pages() from cifs_readv_receive() and then
> loose a network, we issue cifs_reconnect that moves all mids to
> a private list and issue their callbacks. The callback of the async
> read request sets a mid to retry, frees it and wakes up a process
> that waits on the rdata completion.
> 
> After the connection is established we return from read_into_pages()
> with a short read, use the mid that was freed before and try to read
> the remaining data from the a newly created socket. Both actions are
> not what we want to do. In reconnect cases (-EAGAIN) we should not
> mask off the error with a short read but should return the error
> code instead.
> 

I'm not sure I understand what problem this solves. Why is returning a
short read wrong here?

> Cc: Jeff Layton <jlayton-vpEMnDpepFuMZCB2o+C8xQ@public.gmane.org>
> Signed-off-by: Pavel Shilovsky <pshilovsky-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>
> ---
>  fs/cifs/file.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index e90a1e9..6b6df30 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -2823,7 +2823,7 @@ cifs_uncached_read_into_pages(struct TCP_Server_Info *server,
>  		total_read += result;
>  	}
>  
> -	return total_read > 0 ? total_read : result;
> +	return total_read > 0 && result != -EAGAIN ? total_read : result;
>  }
>  
>  ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to)
> @@ -3231,7 +3231,7 @@ cifs_readpages_read_into_pages(struct TCP_Server_Info *server,
>  		total_read += result;
>  	}
>  
> -	return total_read > 0 ? total_read : result;
> +	return total_read > 0 && result != -EAGAIN ? total_read : result;
>  }
>  
>  static int cifs_readpages(struct file *file, struct address_space *mapping,


-- 
Jeff Layton <jlayton-vpEMnDpepFuMZCB2o+C8xQ@public.gmane.org>