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>

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 71c28ff98b564e2f2fa773e0797f6a1516fe2c41..15c605cfcfc8521510aa3acb44b865ea3199ea0a 100644 (file)
--- 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 86840a70ee1ae30e87df2403a1b5621019223fd2..6a94b094a90432b385c5c0cbd8eda1819fc1332d 100644 (file)
--- 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 7ba94b66c91b29064eec986f970d3426d05139f5..d55315a46ecee5aac4808d9ac21b15ed060d1706 100644 (file)
--- 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 b4f0a6a3ba59db43b07153d347c9df5af5211577..2fd61853ba6397d601e1d9e976c77642c29979d6 100644 (file)
--- 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 136484ef35d37de7e4878c54ce98cd35a1326eb7..c700738de1f729c7527599628787329e66c86ec9 100644 (file)
--- 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 7b8d2306b3d3894a313ebb331dcbb18088116c1e..2a7692d7039457d0f2acca13194a1665327a280a 100644 (file)
--- 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);
        }