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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: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This commit is contained in:
Bob Peterson 2019-04-05 04:41:38 +01:00 committed by Andreas Gruenbacher
parent 9287c6452d
commit 73118ca8ba
6 changed files with 31 additions and 15 deletions
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4
fs/gfs2/glock.c
View File

@ -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)

2
fs/gfs2/incore.h
View File

@ -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 */

4
fs/gfs2/log.c
View File

@ -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);
}

33
fs/gfs2/lops.c
View File

@ -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,

1
fs/gfs2/main.c
View File

@ -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)

2
fs/gfs2/super.c
View File

@ -1474,7 +1474,7 @@ static void gfs2_final_release_pages(struct gfs2_inode *ip)
truncate_inode_pages(gfs2_glock2aspace(ip->i_gl), 0);
truncate_inode_pages(&inode->i_data, 0);
if (atomic_read(&gl->gl_revokes) == 0) {
if (!test_bit(GLF_REVOKES, &gl->gl_flags)) {
clear_bit(GLF_LFLUSH, &gl->gl_flags);
clear_bit(GLF_DIRTY, &gl->gl_flags);
}