GFS2: Use generic list_lru for quota

By using the generic list_lru code, we can now separate the
per sb quota list locking from the lru locking. The lru
lock is made into the inner-most lock.

As a result of this new lock order, we may occasionally see
items on the per-sb quota list which are "dead" so that the
two places where we traverse that list are updated to take
account of that.

As a result of this patch, the gfs2 quota shrinker is now
NUMA zone aware, and we are also laying the foundations for
further improvments in due course.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Abhijith Das <adas@redhat.com>
Tested-by: Abhijith Das <adas@redhat.com>
Cc: Dave Chinner <dchinner@redhat.com>

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 9d77804..ba1ea67 100644 (file)
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -420,11 +420,10 @@ enum {
 
 struct gfs2_quota_data {
        struct list_head qd_list;
-       struct list_head qd_reclaim;
-
+       struct kqid qd_id;
        struct lockref qd_lockref;
+       struct list_head qd_lru;
 
-       struct kqid qd_id;
        unsigned long qd_flags;         /* QDF_... */
 
        s64 qd_change;

diff --git a/fs/gfs2/main.c b/fs/gfs2/main.c
index 351586e..0650db2 100644 (file)
--- a/fs/gfs2/main.c
+++ b/fs/gfs2/main.c
@@ -31,12 +31,6 @@
 
 struct workqueue_struct *gfs2_control_wq;
 
-static struct shrinker qd_shrinker = {
-       .count_objects = gfs2_qd_shrink_count,
-       .scan_objects = gfs2_qd_shrink_scan,
-       .seeks = DEFAULT_SEEKS,
-};
-
 static void gfs2_init_inode_once(void *foo)
 {
        struct gfs2_inode *ip = foo;
@@ -87,6 +81,10 @@ static int __init init_gfs2_fs(void)
        if (error)
                return error;
 
+       error = list_lru_init(&gfs2_qd_lru);
+       if (error)
+               goto fail_lru;
+
        error = gfs2_glock_init();
        if (error)
                goto fail;
@@ -139,7 +137,7 @@ static int __init init_gfs2_fs(void)
        if (!gfs2_rsrv_cachep)
                goto fail;
 
-       register_shrinker(&qd_shrinker);
+       register_shrinker(&gfs2_qd_shrinker);
 
        error = register_filesystem(&gfs2_fs_type);
        if (error)
@@ -179,7 +177,9 @@ fail_wq:
 fail_unregister:
        unregister_filesystem(&gfs2_fs_type);
 fail:
-       unregister_shrinker(&qd_shrinker);
+       list_lru_destroy(&gfs2_qd_lru);
+fail_lru:
+       unregister_shrinker(&gfs2_qd_shrinker);
        gfs2_glock_exit();
 
        if (gfs2_rsrv_cachep)
@@ -214,13 +214,14 @@ fail:
 
 static void __exit exit_gfs2_fs(void)
 {
-       unregister_shrinker(&qd_shrinker);
+       unregister_shrinker(&gfs2_qd_shrinker);
        gfs2_glock_exit();
        gfs2_unregister_debugfs();
        unregister_filesystem(&gfs2_fs_type);
        unregister_filesystem(&gfs2meta_fs_type);
        destroy_workqueue(gfs_recovery_wq);
        destroy_workqueue(gfs2_control_wq);
+       list_lru_destroy(&gfs2_qd_lru);
 
        rcu_barrier();
 

diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
index 466516a..453b50e 100644 (file)
--- a/fs/gfs2/quota.c
+++ b/fs/gfs2/quota.c
@@ -51,6 +51,7 @@
 #include <linux/quota.h>
 #include <linux/dqblk_xfs.h>
 #include <linux/lockref.h>
+#include <linux/list_lru.h>
 
 #include "gfs2.h"
 #include "incore.h"
@@ -72,29 +73,25 @@ struct gfs2_quota_change_host {
        struct kqid qc_id;
 };
 
-static LIST_HEAD(qd_lru_list);
-static atomic_t qd_lru_count = ATOMIC_INIT(0);
+/* Lock order: qd_lock -> qd->lockref.lock -> lru lock */
 static DEFINE_SPINLOCK(qd_lock);
+struct list_lru gfs2_qd_lru;
 
-unsigned long gfs2_qd_shrink_scan(struct shrinker *shrink,
-                                 struct shrink_control *sc)
+static void gfs2_qd_dispose(struct list_head *list)
 {
        struct gfs2_quota_data *qd;
        struct gfs2_sbd *sdp;
-       int nr_to_scan = sc->nr_to_scan;
-       long freed = 0;
 
-       if (!(sc->gfp_mask & __GFP_FS))
-               return SHRINK_STOP;
-
-       spin_lock(&qd_lock);
-       while (nr_to_scan && !list_empty(&qd_lru_list)) {
-               qd = list_entry(qd_lru_list.next,
-                               struct gfs2_quota_data, qd_reclaim);
+       while (!list_empty(list)) {
+               qd = list_entry(list->next, struct gfs2_quota_data, qd_lru);
                sdp = qd->qd_gl->gl_sbd;
 
+               list_del(&qd->qd_lru);
+
                /* Free from the filesystem-specific list */
+               spin_lock(&qd_lock);
                list_del(&qd->qd_list);
+               spin_unlock(&qd_lock);
 
                gfs2_assert_warn(sdp, !qd->qd_change);
                gfs2_assert_warn(sdp, !qd->qd_slot_count);
@@ -104,24 +101,59 @@ unsigned long gfs2_qd_shrink_scan(struct shrinker *shrink,
                atomic_dec(&sdp->sd_quota_count);
 
                /* Delete it from the common reclaim list */
-               list_del_init(&qd->qd_reclaim);
-               atomic_dec(&qd_lru_count);
-               spin_unlock(&qd_lock);
                kmem_cache_free(gfs2_quotad_cachep, qd);
-               spin_lock(&qd_lock);
-               nr_to_scan--;
-               freed++;
        }
-       spin_unlock(&qd_lock);
+}
+
+
+static enum lru_status gfs2_qd_isolate(struct list_head *item, spinlock_t *lock, void *arg)
+{
+       struct list_head *dispose = arg;
+       struct gfs2_quota_data *qd = list_entry(item, struct gfs2_quota_data, qd_lru);
+
+       if (!spin_trylock(&qd->qd_lockref.lock))
+               return LRU_SKIP;
+
+       if (qd->qd_lockref.count == 0) {
+               lockref_mark_dead(&qd->qd_lockref);
+               list_move(&qd->qd_lru, dispose);
+       }
+
+       spin_unlock(&qd->qd_lockref.lock);
+       return LRU_REMOVED;
+}
+
+static unsigned long gfs2_qd_shrink_scan(struct shrinker *shrink,
+                                        struct shrink_control *sc)
+{
+       LIST_HEAD(dispose);
+       unsigned long freed;
+
+       if (!(sc->gfp_mask & __GFP_FS))
+               return SHRINK_STOP;
+
+       freed = list_lru_walk_node(&gfs2_qd_lru, sc->nid, gfs2_qd_isolate,
+                                  &dispose, &sc->nr_to_scan);
+
+       gfs2_qd_dispose(&dispose);
+
        return freed;
 }
 
-unsigned long gfs2_qd_shrink_count(struct shrinker *shrink,
-                                  struct shrink_control *sc)
+static unsigned long gfs2_qd_shrink_count(struct shrinker *shrink,
+                                         struct shrink_control *sc)
 {
-       return vfs_pressure_ratio(atomic_read(&qd_lru_count));
+       return vfs_pressure_ratio(list_lru_count_node(&gfs2_qd_lru, sc->nid));
 }
 
+struct shrinker gfs2_qd_shrinker = {
+       .count_objects = gfs2_qd_shrink_count,
+       .scan_objects = gfs2_qd_shrink_scan,
+       .seeks = DEFAULT_SEEKS,
+       .flags = SHRINKER_NUMA_AWARE,
+};
+
+
 static u64 qd2index(struct gfs2_quota_data *qd)
 {
        struct kqid qid = qd->qd_id;
@@ -153,7 +185,7 @@ static int qd_alloc(struct gfs2_sbd *sdp, struct kqid qid,
        spin_lock_init(&qd->qd_lockref.lock);
        qd->qd_id = qid;
        qd->qd_slot = -1;
-       INIT_LIST_HEAD(&qd->qd_reclaim);
+       INIT_LIST_HEAD(&qd->qd_lru);
 
        error = gfs2_glock_get(sdp, qd2index(qd),
                              &gfs2_quota_glops, CREATE, &qd->qd_gl);
@@ -181,13 +213,9 @@ static int qd_get(struct gfs2_sbd *sdp, struct kqid qid,
                found = 0;
                spin_lock(&qd_lock);
                list_for_each_entry(qd, &sdp->sd_quota_list, qd_list) {
-                       if (qid_eq(qd->qd_id, qid)) {
-                               lockref_get(&qd->qd_lockref);
-                               if (!list_empty(&qd->qd_reclaim)) {
-                                       /* Remove it from reclaim list */
-                                       list_del_init(&qd->qd_reclaim);
-                                       atomic_dec(&qd_lru_count);
-                               }
+                       if (qid_eq(qd->qd_id, qid) &&
+                           lockref_get_not_dead(&qd->qd_lockref)) {
+                               list_lru_del(&gfs2_qd_lru, &qd->qd_lru);
                                found = 1;
                                break;
                        }
@@ -229,18 +257,13 @@ static void qd_hold(struct gfs2_quota_data *qd)
 
 static void qd_put(struct gfs2_quota_data *qd)
 {
-       spin_lock(&qd_lock);
-
-       if (!lockref_put_or_lock(&qd->qd_lockref)) {
+       if (lockref_put_or_lock(&qd->qd_lockref))
+               return;
 
-               /* Add to the reclaim list */
-               list_add_tail(&qd->qd_reclaim, &qd_lru_list);
-               atomic_inc(&qd_lru_count);
+       qd->qd_lockref.count = 0;
+       list_lru_add(&gfs2_qd_lru, &qd->qd_lru);
+       spin_unlock(&qd->qd_lockref.lock);
 
-               spin_unlock(&qd->qd_lockref.lock);
-       }
-
-       spin_unlock(&qd_lock);
 }
 
 static int slot_get(struct gfs2_quota_data *qd)
@@ -398,11 +421,11 @@ static int qd_check_sync(struct gfs2_sbd *sdp, struct gfs2_quota_data *qd,
            (sync_gen && (qd->qd_sync_gen >= *sync_gen)))
                return 0;
 
-       list_move_tail(&qd->qd_list, &sdp->sd_quota_list);
+       if (!lockref_get_not_dead(&qd->qd_lockref))
+               return 0;
 
+       list_move_tail(&qd->qd_list, &sdp->sd_quota_list);
        set_bit(QDF_LOCKED, &qd->qd_flags);
-       gfs2_assert_warn(sdp, !__lockref_is_dead(&qd->qd_lockref));
-       lockref_get(&qd->qd_lockref);
        qd->qd_change_sync = qd->qd_change;
        gfs2_assert_warn(sdp, qd->qd_slot_count);
        qd->qd_slot_count++;
@@ -1329,10 +1352,7 @@ void gfs2_quota_cleanup(struct gfs2_sbd *sdp)
 
                list_del(&qd->qd_list);
                /* Also remove if this qd exists in the reclaim list */
-               if (!list_empty(&qd->qd_reclaim)) {
-                       list_del_init(&qd->qd_reclaim);
-                       atomic_dec(&qd_lru_count);
-               }
+               list_lru_del(&gfs2_qd_lru, &qd->qd_lru);
                atomic_dec(&sdp->sd_quota_count);
                spin_unlock(&qd_lock);
 
@@ -1487,7 +1507,7 @@ static int gfs2_quota_get_xstate(struct super_block *sb,
        }
        fqs->qs_uquota.qfs_nextents = 1; /* unsupported */
        fqs->qs_gquota = fqs->qs_uquota; /* its the same inode in both cases */
-       fqs->qs_incoredqs = atomic_read(&qd_lru_count);
+       fqs->qs_incoredqs = list_lru_count(&gfs2_qd_lru);
        return 0;
 }
 

diff --git a/fs/gfs2/quota.h b/fs/gfs2/quota.h
index 0f64d9d..96e4f34 100644 (file)
--- a/fs/gfs2/quota.h
+++ b/fs/gfs2/quota.h
@@ -10,9 +10,10 @@
 #ifndef __QUOTA_DOT_H__
 #define __QUOTA_DOT_H__
 
+#include <linux/list_lru.h>
+
 struct gfs2_inode;
 struct gfs2_sbd;
-struct shrink_control;
 
 #define NO_UID_QUOTA_CHANGE INVALID_UID
 #define NO_GID_QUOTA_CHANGE INVALID_GID
@@ -53,10 +54,8 @@ static inline int gfs2_quota_lock_check(struct gfs2_inode *ip)
        return ret;
 }
 
-extern unsigned long gfs2_qd_shrink_count(struct shrinker *shrink,
-                                         struct shrink_control *sc);
-extern unsigned long gfs2_qd_shrink_scan(struct shrinker *shrink,
-                                        struct shrink_control *sc);
 extern const struct quotactl_ops gfs2_quotactl_ops;
+extern struct shrinker gfs2_qd_shrinker;
+extern struct list_lru gfs2_qd_lru;
 
 #endif /* __QUOTA_DOT_H__ */