[Cluster-devel] [GFS2 PATCH v3 03/14] GFS2: Protect log tail calculations with inside locks

[Steven Whitehouse <swhiteho@redhat.com>]

Hi,

sd_log_tail should be protected by sdp->sd_log_flush_lock, so is that 
not happening for some reason?

Steve.

On 22/10/15 20:30, Bob Peterson wrote:
> This patch moves the variables "old_tail" and "wrap" in function
> gfs2_ail2_empty_one inside the protective spin_lock so they can't
> be moved by another process. If the calculations aren't protected,
> the log's tail may not be properly pulled, which eventually makes
> it seem like there isn't enough room in the journal for more
> transactions. This results in a hang where GFS2 repeatedly does
> log flushes without making any progress.
>
> Signed-off-by: Bob Peterson <rpeterso@redhat.com>
> ---
>   fs/gfs2/log.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
> index 536e7a6..18959de 100644
> --- a/fs/gfs2/log.c
> +++ b/fs/gfs2/log.c
> @@ -277,11 +277,12 @@ static void gfs2_ail2_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
>   static void ail2_empty(struct gfs2_sbd *sdp, unsigned int new_tail)
>   {
>   	struct gfs2_trans *tr, *safe;
> -	unsigned int old_tail = sdp->sd_log_tail;
> -	int wrap = (new_tail < old_tail);
> -	int a, b, rm;
> +	unsigned int old_tail;
> +	int wrap, a, b, rm;
>   
>   	spin_lock(&sdp->sd_ail_lock);
> +	old_tail = sdp->sd_log_tail;
> +	wrap = (new_tail < old_tail);
>   
>   	list_for_each_entry_safe(tr, safe, &sdp->sd_ail2_list, tr_list) {
>   		a = (old_tail <= tr->tr_first);