From: Bob Peterson <rpete...@redhat.com>
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 <rpete...@redhat.com>
Signed-off-by: Andreas Gruenbacher <agrue...@redhat.com>
---
fs/gfs2/glock.c | 4 ++--
fs/gfs2/incore.h | 2 +-
fs/gfs2/log.c | 4 +++-
fs/gfs2/lops.c | 33 ++++++++++++++++++++++++---------
fs/gfs2/main.c | 1 -
fs/gfs2/super.c | 2 +-
6 files changed, 31 insertions(+), 15 deletions(-)
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 71c28ff98b56..15c605cfcfc8 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -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)
diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 86840a70ee1a..6a94b094a904 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -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 */
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 7ba94b66c91b..d55315a46ece 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -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);
}
diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index b4f0a6a3ba59..2fd61853ba63 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -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,
diff --git a/fs/gfs2/main.c b/fs/gfs2/main.c
index 136484ef35d3..c700738de1f7 100644
--- a/fs/gfs2/main.c
+++ b/fs/gfs2/main.c
@@ -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)
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index ca71163ff7cf..e20fa55715e2 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -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);
}
--
2.20.1
