Re: [PATCH 6/7] writeback: requeue_io_wait() on blocked inode

[Jan Kara <jack@suse.cz>]

On Thu 20-10-11 23:22:46, Wu Fengguang wrote:
> Use requeue_io_wait() if inode is somehow blocked.
> 
> CC: Jan Kara <jack@suse.cz>
> CC: Dave Chinner <david@fromorbit.com>
> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
  Acked-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/fs-writeback.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- linux-next.orig/fs/fs-writeback.c	2011-10-20 22:42:25.000000000 +0800
> +++ linux-next/fs/fs-writeback.c	2011-10-20 22:43:42.000000000 +0800
> @@ -471,25 +471,25 @@ writeback_single_inode(struct inode *ino
>  				/*
>  				 * slice used up: queue for next turn
>  				 */
>  				requeue_io(inode, wb);
>  			} else {
>  				/*
>  				 * Writeback blocked by something other than
>  				 * congestion. Delay the inode for some time to
>  				 * avoid spinning on the CPU (100% iowait)
>  				 * retrying writeback of the dirty page/inode
>  				 * that cannot be performed immediately.
>  				 */
> -				redirty_tail(inode, wb);
> +				requeue_io_wait(inode, wb);
>  			}
>  		} else if (inode->i_state & I_DIRTY) {
>  			/*
>  			 * Filesystems can dirty the inode during writeback
>  			 * operations, such as delayed allocation during
>  			 * submission or metadata updates after data IO
>  			 * completion.
>  			 *
>  			 * For the latter case it is very important to give
>  			 * the inode another turn on b_more_io instead of
>  			 * redirtying it.  Constantly moving dirtied_when
>  			 * forward will prevent us from ever writing out
> 
> 
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR