Commit 73118ca8 authored by Bob Peterson's avatar Bob Peterson Committed by Andreas Gruenbacher
Browse files

gfs2: Replace gl_revokes with a GLF flag 



The gl_revokes value determines how many outstanding revokes a glock has
on the superblock revokes list; this is used to avoid unnecessary log
flushes.  However, gl_revokes is only ever tested for being zero, and it's
only decremented in revoke_lo_after_commit, which removes all revokes
from the list, so we know that the gl_revoke values of all the glocks on
the list will reach zero.  Therefore, we can replace gl_revokes with a
bit flag. This saves an atomic counter in struct gfs2_glock.

Signed-off-by: default avatarBob Peterson <rpeterso@redhat.com>
Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
parent 9287c645

fs/gfs2/glock.c

+2 −2
Original line number Diff line number Diff line
@@ -140,7 +140,7 @@ void gfs2_glock_free(struct gfs2_glock *gl) 
{

	struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;



	BUG_ON(atomic_read(&gl->gl_revokes));

	BUG_ON(test_bit(GLF_REVOKES, &gl->gl_flags));

	rhashtable_remove_fast(&gl_hash_table, &gl->gl_node, ht_parms);

	smp_mb();

	wake_up_glock(gl);
@@ -1801,7 +1801,7 @@ void gfs2_dump_glock(struct seq_file *seq, struct gfs2_glock *gl) 
		  state2str(gl->gl_target),

		  state2str(gl->gl_demote_state), dtime,

		  atomic_read(&gl->gl_ail_count),

		  atomic_read(&gl->gl_revokes),

		  test_bit(GLF_REVOKES, &gl->gl_flags) ? 1 : 0,

		  (int)gl->gl_lockref.count, gl->gl_hold_time);



	list_for_each_entry(gh, &gl->gl_holders, gh_list)

fs/gfs2/incore.h

+1 −1
Original line number Diff line number Diff line
@@ -345,6 +345,7 @@ enum { 
	GLF_OBJECT			= 14, /* Used only for tracing */

	GLF_BLOCKING			= 15,

	GLF_INODE_CREATING		= 16, /* Inode creation occurring */

	GLF_REVOKES			= 17, /* Glock has revokes in queue */

};



struct gfs2_glock {
@@ -374,7 +375,6 @@ struct gfs2_glock { 
	struct list_head gl_lru;

	struct list_head gl_ail_list;

	atomic_t gl_ail_count;

	atomic_t gl_revokes;

	struct delayed_work gl_work;

	union {

		/* For inode and iopen glocks only */

fs/gfs2/log.c

+3 −1
Original line number Diff line number Diff line
@@ -606,8 +606,10 @@ void gfs2_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd) 
	gfs2_remove_from_ail(bd); /* drops ref on bh */

	bd->bd_bh = NULL;

	sdp->sd_log_num_revoke++;

	if (atomic_inc_return(&gl->gl_revokes) == 1)

	if (!test_bit(GLF_REVOKES, &gl->gl_flags)) {

		set_bit(GLF_REVOKES, &gl->gl_flags);

		gfs2_glock_hold(gl);

	}

	set_bit(GLF_LFLUSH, &gl->gl_flags);

	list_add(&bd->bd_list, &sdp->sd_log_le_revoke);

}

fs/gfs2/lops.c

+24 −9
Original line number Diff line number Diff line
@@ -662,19 +662,34 @@ static void revoke_lo_before_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr) 
static void revoke_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)

{

	struct list_head *head = &sdp->sd_log_le_revoke;

	struct gfs2_bufdata *bd;

	struct gfs2_glock *gl;

	struct gfs2_bufdata *bd, *tmp;



	while (!list_empty(head)) {

		bd = list_entry(head->next, struct gfs2_bufdata, bd_list);

		list_del_init(&bd->bd_list);

		gl = bd->bd_gl;

		if (atomic_dec_return(&gl->gl_revokes) == 0) {

			clear_bit(GLF_LFLUSH, &gl->gl_flags);

			gfs2_glock_queue_put(gl);

	/*

	 * Glocks can be referenced repeatedly on the revoke list, but the list

	 * only holds one reference.  All glocks on the list will have the

	 * GLF_REVOKES flag set initially.

	 */



	list_for_each_entry_safe(bd, tmp, head, bd_list) {

		struct gfs2_glock *gl = bd->bd_gl;



		if (test_bit(GLF_REVOKES, &gl->gl_flags)) {

			/* Keep each glock on the list exactly once. */

			clear_bit(GLF_REVOKES, &gl->gl_flags);

			continue;

		}

		list_del(&bd->bd_list);

		kmem_cache_free(gfs2_bufdata_cachep, bd);

	}

	list_for_each_entry_safe(bd, tmp, head, bd_list) {

		struct gfs2_glock *gl = bd->bd_gl;



		list_del(&bd->bd_list);

		kmem_cache_free(gfs2_bufdata_cachep, bd);

		clear_bit(GLF_LFLUSH, &gl->gl_flags);

		gfs2_glock_queue_put(gl);

	}

	/* the list is empty now */

}



static void revoke_lo_before_scan(struct gfs2_jdesc *jd,

fs/gfs2/main.c

+0 −1
Original line number Diff line number Diff line
@@ -59,7 +59,6 @@ static void gfs2_init_glock_once(void *foo) 
	INIT_LIST_HEAD(&gl->gl_lru);

	INIT_LIST_HEAD(&gl->gl_ail_list);

	atomic_set(&gl->gl_ail_count, 0);

	atomic_set(&gl->gl_revokes, 0);

}



static void gfs2_init_gl_aspace_once(void *foo)

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