[Cluster-devel] [GFS2 PATCH] Minor speedup to ordered writes

[Steven Whitehouse]

Hi,

On Mon, 2012-02-20 at 10:11 -0500, Bob Peterson wrote:
> ----- Original Message -----
> | Hi,
> | 
> | I like the idea of not having to hold the lock for so long, but what
> | protects the list again the buffers being reclaimed? So far as I can
> | tell, that could happen at any time after the i/o has completed and
> | the
> | buffer is clean,
> | 
> | Steve.
> 
> Hi,
> 
> The sd_log_le_ordered list is still protected by the log_lock.
> 
> The first thing we do is isolate the sd_log_le_ordered list to a
> private list_head to protect it.
> 
> The working bd list, towrite, is protected by virtue of the fact that
> the list head is a private variable. The reclaims might reclaim some of
> the bh, but the bd list shouldn't be manipulated by anyone but the
> function it's declared in.
> 
> Unless I'm totally missing what you mean.
> 
> Regards,
> 
> Bob Peterson
> Red Hat File Systems

At page reclaim time, the log lock is used to protect the removal of the
bd from the list. It doesn't matter which list the bd is on, it will be
removed from it just the same, see gfs2_releasepage()

Steve.