[Cluster-devel] [PATCH] GFS2: Allow the number of committed revokes to temporarily be negative

[Steven Whitehouse <swhiteho@redhat.com>]

Hi,

Now in the -nmw git tree. Thanks,

Steve.

On Wed, 2010-03-10 at 18:10 -0600, Benjamin Marzinski wrote:
> GFS2 tracks the number of revokes and unrevokes that are part of committed
> transactions via sd_log_commited_revoke. It is possible for one process to add
> revokes during its transaction, while another process unrevokes them during its
> transaction. If the second process finishes its transaction first,
> sd_log_commited_revoke will be decremented by the number of unrevokes that the
> second process did, without first being incremented by the number of revokes
> the first process did. This is fine, since all started transactions must be
> completed before the journal can be flushed.  However, sd_log_commited_revoke
> is an unsigned integer, and log_refund() causes an assertion failure if it
> would go negative at the end of a transaction.  This patch makes
> sd_log_commited_revoke a signed integer and allows it to go negative.
> __gfs2_log_flush() still checks that it mataches the actual number of revokes. 
> 
> Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
> ---
>  fs/gfs2/incore.h |    2 +-
>  fs/gfs2/log.c    |    3 +--
>  2 files changed, 2 insertions(+), 3 deletions(-)
> 
> Index: gfs2-2.6-nmw/fs/gfs2/log.c
> ===================================================================
> --- gfs2-2.6-nmw.orig/fs/gfs2/log.c
> +++ gfs2-2.6-nmw/fs/gfs2/log.c
> @@ -417,7 +417,7 @@ static unsigned int calc_reserved(struct
>  	databufhdrs_needed = (sdp->sd_log_commited_databuf +
>  			      (dbuf_limit - 1)) / dbuf_limit;
>  
> -	if (sdp->sd_log_commited_revoke)
> +	if (sdp->sd_log_commited_revoke > 0)
>  		revokes = gfs2_struct2blk(sdp, sdp->sd_log_commited_revoke,
>  					  sizeof(u64));
>  
> @@ -790,7 +790,6 @@ static void log_refund(struct gfs2_sbd *
>  	gfs2_assert_withdraw(sdp, (((int)sdp->sd_log_commited_buf) >= 0) ||
>  			     (((int)sdp->sd_log_commited_databuf) >= 0));
>  	sdp->sd_log_commited_revoke += tr->tr_num_revoke - tr->tr_num_revoke_rm;
> -	gfs2_assert_withdraw(sdp, ((int)sdp->sd_log_commited_revoke) >= 0);
>  	reserved = calc_reserved(sdp);
>  	gfs2_assert_withdraw(sdp, sdp->sd_log_blks_reserved + tr->tr_reserved >= reserved);
>  	unused = sdp->sd_log_blks_reserved - reserved + tr->tr_reserved;
> Index: gfs2-2.6-nmw/fs/gfs2/incore.h
> ===================================================================
> --- gfs2-2.6-nmw.orig/fs/gfs2/incore.h
> +++ gfs2-2.6-nmw/fs/gfs2/incore.h
> @@ -616,7 +616,7 @@ struct gfs2_sbd {
>  	unsigned int sd_log_blks_reserved;
>  	unsigned int sd_log_commited_buf;
>  	unsigned int sd_log_commited_databuf;
> -	unsigned int sd_log_commited_revoke;
> +	int sd_log_commited_revoke;
>  
>  	unsigned int sd_log_num_buf;
>  	unsigned int sd_log_num_revoke;
>