Hi,
On Thu, 2012-11-08 at 16:34 -0500, David Teigland wrote:
> When unmounting, gfs2 does a full dlm_unlock operation on every
> cached lock. This can create a very large amount of work and can
> take a long time to complete. However, the vast majority of these
> dlm unlock operations are unnecessary because after all the unlocks
> are done, gfs2 leaves the dlm lockspace, which automatically clears
> the locks of the leaving node, without unlocking each one individually.
> So, gfs2 can skip explicit dlm unlocks, and use dlm_release_lockspace to
> remove the locks implicitly. The one exception is when the lock's lvb is
> being used. In this case, dlm_unlock is called because it may update the
> lvb of the resource.
>
> Signed-off-by: David Teigland <teigl...@redhat.com>
> ---
> fs/gfs2/glock.c | 1 +
> fs/gfs2/incore.h | 1 +
> fs/gfs2/lock_dlm.c | 8 ++++++++
> 3 files changed, 10 insertions(+)
>
> diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
> index e6c2fd5..f3a5edb 100644
> --- a/fs/gfs2/glock.c
> +++ b/fs/gfs2/glock.c
> @@ -1528,6 +1528,7 @@ static void dump_glock_func(struct gfs2_glock *gl)
>
> void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
> {
> + set_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags);
> glock_hash_walk(clear_glock, sdp);
> flush_workqueue(glock_workqueue);
> wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) ==
> 0);
> diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
> index 3d469d3..67a39cf 100644
> --- a/fs/gfs2/incore.h
> +++ b/fs/gfs2/incore.h
> @@ -539,6 +539,7 @@ enum {
> SDF_DEMOTE = 5,
> SDF_NOJOURNALID = 6,
> SDF_RORECOVERY = 7, /* read only recovery */
> + SDF_SKIP_DLM_UNLOCK = 8,
> };
>
> #define GFS2_FSNAME_LEN 256
> diff --git a/fs/gfs2/lock_dlm.c b/fs/gfs2/lock_dlm.c
> index 0fb6539..806a639 100644
> --- a/fs/gfs2/lock_dlm.c
> +++ b/fs/gfs2/lock_dlm.c
> @@ -289,6 +289,14 @@ static void gdlm_put_lock(struct gfs2_glock *gl)
> gfs2_glstats_inc(gl, GFS2_LKS_DCOUNT);
> gfs2_sbstats_inc(gl, GFS2_LKS_DCOUNT);
> gfs2_update_request_times(gl);
> +
> + /* don't want to skip dlm_unlock writing the lvb when lock is ex */
> + if (test_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags) &&
> + (!gl->gl_lvb[0] || gl->gl_state != LM_ST_EXCLUSIVE)) {
I'm still not happy with using !gl->gl_lvb[0] to determine whether the
LVB is in use or not. I think we need a better test, or alternatively
just test the lock state, since most locks will be NL anyway before they
get to this point in time,
Steve.
> + gfs2_glock_free(gl);
> + return;
> + }
> +
> error = dlm_unlock(ls->ls_dlm, gl->gl_lksb.sb_lkid, DLM_LKF_VALBLK,
> NULL, gl);
> if (error) {
