Revert "gfs2: Replace gl_revokes with a GLF flag"

Commit 73118ca8baf7 introduced a glock reference counting bug in
gfs2_trans_remove_revoke.  Given that, replacing gl_revokes with a GLF flag is
no longer useful, so revert that commit.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

6 files changed, 15 insertions, 31 deletions

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 15c605cfcfc8..71c28ff98b56 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(test_bit(GLF_REVOKES, &gl->gl_flags));
+        BUG_ON(atomic_read(&gl->gl_revokes));
         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),
-                  test_bit(GLF_REVOKES, &gl->gl_flags) ? 1 : 0,
+                  atomic_read(&gl->gl_revokes),
                   (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 b15755068593..1d35e0da0ef8 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -345,7 +345,6 @@ 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 {
@@ -375,6 +374,7 @@ 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 a2e1df488df0..86703c95353e 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -606,10 +606,8 @@ 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 (!test_bit(GLF_REVOKES, &gl->gl_flags)) {
-                set_bit(GLF_REVOKES, &gl->gl_flags);
+        if (atomic_inc_return(&gl->gl_revokes) == 1)
                 gfs2_glock_hold(gl);
-        }
         set_bit(GLF_LFLUSH, &gl->gl_flags);
         list_add(&bd->bd_list, &sdp->sd_log_revokes);
 }
diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index 33ab662c9aac..bb0e5b8e445e 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -860,34 +860,19 @@ 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_revokes;
-        struct gfs2_bufdata *bd, *tmp;
-
-        /*
-         * 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;
+        struct gfs2_bufdata *bd;
+        struct gfs2_glock *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;
+        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);
                 }
-                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 c700738de1f7..136484ef35d3 100644
--- a/fs/gfs2/main.c
+++ b/fs/gfs2/main.c
@@ -59,6 +59,7 @@ 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 fbf6b1fd330b..2aa4dd050f3d 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -1477,7 +1477,7 @@ 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 (!test_bit(GLF_REVOKES, &gl->gl_flags)) {
+        if (atomic_read(&gl->gl_revokes) == 0) {
                 clear_bit(GLF_LFLUSH, &gl->gl_flags);
                 clear_bit(GLF_DIRTY, &gl->gl_flags);
         }