GFS2: change gfs2_quota_scan into a shrinker

Deallocation of gfs2_quota_data objects now happens on-demand through a
shrinker instead of routinely deallocating through the quotad daemon.

Signed-off-by: Abhijith Das <adas@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

7 files changed, 114 insertions, 73 deletions

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 608849d00021..592aa5040d29 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -283,7 +283,9 @@ enum {
 
 struct gfs2_quota_data {
         struct list_head qd_list;
-        unsigned int qd_count;
+        struct list_head qd_reclaim;
+
+        atomic_t qd_count;
 
         u32 qd_id;
         unsigned long qd_flags;         /* QDF_... */
@@ -303,7 +305,6 @@ struct gfs2_quota_data {
 
         u64 qd_sync_gen;
         unsigned long qd_last_warn;
-        unsigned long qd_last_touched;
 };
 
 struct gfs2_trans {
@@ -406,7 +407,6 @@ struct gfs2_tune {
         unsigned int gt_quota_warn_period; /* Secs between quota warn msgs */
         unsigned int gt_quota_scale_num; /* Numerator */
         unsigned int gt_quota_scale_den; /* Denominator */
-        unsigned int gt_quota_cache_secs;
         unsigned int gt_quota_quantum; /* Secs between syncs to quota file */
         unsigned int gt_new_files_jdata;
         unsigned int gt_max_readahead; /* Max bytes to read-ahead from disk */
diff --git a/fs/gfs2/main.c b/fs/gfs2/main.c
index 7cacfde32194..86fe06798711 100644
--- a/fs/gfs2/main.c
+++ b/fs/gfs2/main.c
@@ -23,6 +23,12 @@
 #include "sys.h"
 #include "util.h"
 #include "glock.h"
+#include "quota.h"
+
+static struct shrinker qd_shrinker = {
+        .shrink = gfs2_shrink_qd_memory,
+        .seeks = DEFAULT_SEEKS,
+};
 
 static void gfs2_init_inode_once(void *foo)
 {
@@ -100,6 +106,8 @@ static int __init init_gfs2_fs(void)
         if (!gfs2_quotad_cachep)
                 goto fail;
 
+        register_shrinker(&qd_shrinker);
+
         error = register_filesystem(&gfs2_fs_type);
         if (error)
                 goto fail;
@@ -117,6 +125,7 @@ static int __init init_gfs2_fs(void)
 fail_unregister:
         unregister_filesystem(&gfs2_fs_type);
 fail:
+        unregister_shrinker(&qd_shrinker);
         gfs2_glock_exit();
 
         if (gfs2_quotad_cachep)
@@ -145,6 +154,7 @@ fail:
 
 static void __exit exit_gfs2_fs(void)
 {
+        unregister_shrinker(&qd_shrinker);
         gfs2_glock_exit();
         gfs2_unregister_debugfs();
         unregister_filesystem(&gfs2_fs_type);
diff --git a/fs/gfs2/ops_address.c b/fs/gfs2/ops_address.c
index 4ddab67867eb..dde4ead2c3be 100644
--- a/fs/gfs2/ops_address.c
+++ b/fs/gfs2/ops_address.c
@@ -442,6 +442,7 @@ static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
          */
         if (unlikely(page->index)) {
                 zero_user(page, 0, PAGE_CACHE_SIZE);
+                SetPageUptodate(page);
                 return 0;
         }
 
diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index 3eb49edae542..530d3f6f6ea8 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -63,7 +63,6 @@ static void gfs2_tune_init(struct gfs2_tune *gt)
         gt->gt_quota_warn_period = 10;
         gt->gt_quota_scale_num = 1;
         gt->gt_quota_scale_den = 1;
-        gt->gt_quota_cache_secs = 300;
         gt->gt_quota_quantum = 60;
         gt->gt_new_files_jdata = 0;
         gt->gt_max_readahead = 1 << 18;
diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
index b08d09696b3e..2ada6e10d07b 100644
--- a/fs/gfs2/quota.c
+++ b/fs/gfs2/quota.c
@@ -80,6 +80,53 @@ struct gfs2_quota_change_host {
         u32 qc_id;
 };
 
+static LIST_HEAD(qd_lru_list);
+static atomic_t qd_lru_count = ATOMIC_INIT(0);
+static spinlock_t qd_lru_lock = SPIN_LOCK_UNLOCKED;
+
+int gfs2_shrink_qd_memory(int nr, gfp_t gfp_mask)
+{
+        struct gfs2_quota_data *qd;
+        struct gfs2_sbd *sdp;
+
+        if (nr == 0)
+                goto out;
+
+        if (!(gfp_mask & __GFP_FS))
+                return -1;
+
+        spin_lock(&qd_lru_lock);
+        while (nr && !list_empty(&qd_lru_list)) {
+                qd = list_entry(qd_lru_list.next,
+                                struct gfs2_quota_data, qd_reclaim);
+                sdp = qd->qd_gl->gl_sbd;
+
+                /* Free from the filesystem-specific list */
+                list_del(&qd->qd_list);
+
+                spin_lock(&sdp->sd_quota_spin);
+                gfs2_assert_warn(sdp, !qd->qd_change);
+                gfs2_assert_warn(sdp, !qd->qd_slot_count);
+                gfs2_assert_warn(sdp, !qd->qd_bh_count);
+
+                gfs2_lvb_unhold(qd->qd_gl);
+                spin_unlock(&sdp->sd_quota_spin);
+                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_lru_lock);
+                kmem_cache_free(gfs2_quotad_cachep, qd);
+                spin_lock(&qd_lru_lock);
+                nr--;
+        }
+        spin_unlock(&qd_lru_lock);
+
+out:
+        return (atomic_read(&qd_lru_count) * sysctl_vfs_cache_pressure) / 100;
+}
+
 static u64 qd2offset(struct gfs2_quota_data *qd)
 {
         u64 offset;
@@ -100,11 +147,12 @@ static int qd_alloc(struct gfs2_sbd *sdp, int user, u32 id,
         if (!qd)
                 return -ENOMEM;
 
-        qd->qd_count = 1;
+        atomic_set(&qd->qd_count, 1);
         qd->qd_id = id;
         if (user)
                 set_bit(QDF_USER, &qd->qd_flags);
         qd->qd_slot = -1;
+        INIT_LIST_HEAD(&qd->qd_reclaim);
 
         error = gfs2_glock_get(sdp, 2 * (u64)id + !user,
                               &gfs2_quota_glops, CREATE, &qd->qd_gl);
@@ -135,11 +183,17 @@ static int qd_get(struct gfs2_sbd *sdp, int user, u32 id, int create,
 
         for (;;) {
                 found = 0;
-                spin_lock(&sdp->sd_quota_spin);
+                spin_lock(&qd_lru_lock);
                 list_for_each_entry(qd, &sdp->sd_quota_list, qd_list) {
                         if (qd->qd_id == id &&
                             !test_bit(QDF_USER, &qd->qd_flags) == !user) {
-                                qd->qd_count++;
+                                if (!atomic_read(&qd->qd_count) &&
+                                    !list_empty(&qd->qd_reclaim)) {
+                                        /* Remove it from reclaim list */
+                                        list_del_init(&qd->qd_reclaim);
+                                        atomic_dec(&qd_lru_count);
+                                }
+                                atomic_inc(&qd->qd_count);
                                 found = 1;
                                 break;
                         }
@@ -155,7 +209,7 @@ static int qd_get(struct gfs2_sbd *sdp, int user, u32 id, int create,
                         new_qd = NULL;
                 }
 
-                spin_unlock(&sdp->sd_quota_spin);
+                spin_unlock(&qd_lru_lock);
 
                 if (qd || !create) {
                         if (new_qd) {
@@ -175,21 +229,18 @@ static int qd_get(struct gfs2_sbd *sdp, int user, u32 id, int create,
 static void qd_hold(struct gfs2_quota_data *qd)
 {
         struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;
-
-        spin_lock(&sdp->sd_quota_spin);
-        gfs2_assert(sdp, qd->qd_count);
-        qd->qd_count++;
-        spin_unlock(&sdp->sd_quota_spin);
+        gfs2_assert(sdp, atomic_read(&qd->qd_count));
+        atomic_inc(&qd->qd_count);
 }
 
 static void qd_put(struct gfs2_quota_data *qd)
 {
-        struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;
-        spin_lock(&sdp->sd_quota_spin);
-        gfs2_assert(sdp, qd->qd_count);
-        if (!--qd->qd_count)
-                qd->qd_last_touched = jiffies;
-        spin_unlock(&sdp->sd_quota_spin);
+        if (atomic_dec_and_lock(&qd->qd_count, &qd_lru_lock)) {
+                /* Add to the reclaim list */
+                list_add_tail(&qd->qd_reclaim, &qd_lru_list);
+                atomic_inc(&qd_lru_count);
+                spin_unlock(&qd_lru_lock);
+        }
 }
 
 static int slot_get(struct gfs2_quota_data *qd)
@@ -330,6 +381,7 @@ static int qd_fish(struct gfs2_sbd *sdp, struct gfs2_quota_data **qdp)
         if (sdp->sd_vfs->s_flags & MS_RDONLY)
                 return 0;
 
+        spin_lock(&qd_lru_lock);
         spin_lock(&sdp->sd_quota_spin);
 
         list_for_each_entry(qd, &sdp->sd_quota_list, qd_list) {
@@ -341,8 +393,8 @@ static int qd_fish(struct gfs2_sbd *sdp, struct gfs2_quota_data **qdp)
                 list_move_tail(&qd->qd_list, &sdp->sd_quota_list);
 
                 set_bit(QDF_LOCKED, &qd->qd_flags);
-                gfs2_assert_warn(sdp, qd->qd_count);
-                qd->qd_count++;
+                gfs2_assert_warn(sdp, atomic_read(&qd->qd_count));
+                atomic_inc(&qd->qd_count);
                 qd->qd_change_sync = qd->qd_change;
                 gfs2_assert_warn(sdp, qd->qd_slot_count);
                 qd->qd_slot_count++;
@@ -355,6 +407,7 @@ static int qd_fish(struct gfs2_sbd *sdp, struct gfs2_quota_data **qdp)
                 qd = NULL;
 
         spin_unlock(&sdp->sd_quota_spin);
+        spin_unlock(&qd_lru_lock);
 
         if (qd) {
                 gfs2_assert_warn(sdp, qd->qd_change_sync);
@@ -379,24 +432,27 @@ static int qd_trylock(struct gfs2_quota_data *qd)
         if (sdp->sd_vfs->s_flags & MS_RDONLY)
                 return 0;
 
+        spin_lock(&qd_lru_lock);
         spin_lock(&sdp->sd_quota_spin);
 
         if (test_bit(QDF_LOCKED, &qd->qd_flags) ||
             !test_bit(QDF_CHANGE, &qd->qd_flags)) {
                 spin_unlock(&sdp->sd_quota_spin);
+                spin_unlock(&qd_lru_lock);
                 return 0;
         }
 
         list_move_tail(&qd->qd_list, &sdp->sd_quota_list);
 
         set_bit(QDF_LOCKED, &qd->qd_flags);
-        gfs2_assert_warn(sdp, qd->qd_count);
-        qd->qd_count++;
+        gfs2_assert_warn(sdp, atomic_read(&qd->qd_count));
+        atomic_inc(&qd->qd_count);
         qd->qd_change_sync = qd->qd_change;
         gfs2_assert_warn(sdp, qd->qd_slot_count);
         qd->qd_slot_count++;
 
         spin_unlock(&sdp->sd_quota_spin);
+        spin_unlock(&qd_lru_lock);
 
         gfs2_assert_warn(sdp, qd->qd_change_sync);
         if (bh_get(qd)) {
@@ -802,8 +858,8 @@ restart:
                 loff_t pos;
                 gfs2_glock_dq_uninit(q_gh);
                 error = gfs2_glock_nq_init(qd->qd_gl,
-                                          LM_ST_EXCLUSIVE, GL_NOCACHE,
-                                          q_gh);
+                                           LM_ST_EXCLUSIVE, GL_NOCACHE,
+                                           q_gh);
                 if (error)
                         return error;
 
@@ -820,7 +876,6 @@ restart:
 
                 gfs2_glock_dq_uninit(&i_gh);
 
-
                 gfs2_quota_in(&q, buf);
                 qlvb = (struct gfs2_quota_lvb *)qd->qd_gl->gl_lvb;
                 qlvb->qb_magic = cpu_to_be32(GFS2_MAGIC);
@@ -1171,13 +1226,14 @@ int gfs2_quota_init(struct gfs2_sbd *sdp)
                         qd->qd_change = qc.qc_change;
                         qd->qd_slot = slot;
                         qd->qd_slot_count = 1;
-                        qd->qd_last_touched = jiffies;
 
+                        spin_lock(&qd_lru_lock);
                         spin_lock(&sdp->sd_quota_spin);
                         gfs2_icbit_munge(sdp, sdp->sd_quota_bitmap, slot, 1);
+                        spin_unlock(&sdp->sd_quota_spin);
                         list_add(&qd->qd_list, &sdp->sd_quota_list);
                         atomic_inc(&sdp->sd_quota_count);
-                        spin_unlock(&sdp->sd_quota_spin);
+                        spin_unlock(&qd_lru_lock);
 
                         found++;
                 }
@@ -1197,61 +1253,39 @@ fail:
         return error;
 }
 
-static void gfs2_quota_scan(struct gfs2_sbd *sdp)
-{
-        struct gfs2_quota_data *qd, *safe;
-        LIST_HEAD(dead);
-
-        spin_lock(&sdp->sd_quota_spin);
-        list_for_each_entry_safe(qd, safe, &sdp->sd_quota_list, qd_list) {
-                if (!qd->qd_count &&
-                    time_after_eq(jiffies, qd->qd_last_touched +
-                                gfs2_tune_get(sdp, gt_quota_cache_secs) * HZ)) {
-                        list_move(&qd->qd_list, &dead);
-                        gfs2_assert_warn(sdp,
-                                         atomic_read(&sdp->sd_quota_count) > 0);
-                        atomic_dec(&sdp->sd_quota_count);
-                }
-        }
-        spin_unlock(&sdp->sd_quota_spin);
-
-        while (!list_empty(&dead)) {
-                qd = list_entry(dead.next, struct gfs2_quota_data, qd_list);
-                list_del(&qd->qd_list);
-
-                gfs2_assert_warn(sdp, !qd->qd_change);
-                gfs2_assert_warn(sdp, !qd->qd_slot_count);
-                gfs2_assert_warn(sdp, !qd->qd_bh_count);
-
-                gfs2_lvb_unhold(qd->qd_gl);
-                kmem_cache_free(gfs2_quotad_cachep, qd);
-        }
-}
-
 void gfs2_quota_cleanup(struct gfs2_sbd *sdp)
 {
         struct list_head *head = &sdp->sd_quota_list;
         struct gfs2_quota_data *qd;
         unsigned int x;
 
-        spin_lock(&sdp->sd_quota_spin);
+        spin_lock(&qd_lru_lock);
         while (!list_empty(head)) {
                 qd = list_entry(head->prev, struct gfs2_quota_data, qd_list);
 
-                if (qd->qd_count > 1 ||
-                    (qd->qd_count && !test_bit(QDF_CHANGE, &qd->qd_flags))) {
-                        list_move(&qd->qd_list, head);
+                spin_lock(&sdp->sd_quota_spin);
+                if (atomic_read(&qd->qd_count) > 1 ||
+                    (atomic_read(&qd->qd_count) &&
+                     !test_bit(QDF_CHANGE, &qd->qd_flags))) {
                         spin_unlock(&sdp->sd_quota_spin);
+                        list_move(&qd->qd_list, head);
+                        spin_unlock(&qd_lru_lock);
                         schedule();
-                        spin_lock(&sdp->sd_quota_spin);
+                        spin_lock(&qd_lru_lock);
                         continue;
                 }
+                spin_unlock(&sdp->sd_quota_spin);
 
                 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);
+                }
                 atomic_dec(&sdp->sd_quota_count);
-                spin_unlock(&sdp->sd_quota_spin);
+                spin_unlock(&qd_lru_lock);
 
-                if (!qd->qd_count) {
+                if (!atomic_read(&qd->qd_count)) {
                         gfs2_assert_warn(sdp, !qd->qd_change);
                         gfs2_assert_warn(sdp, !qd->qd_slot_count);
                 } else
@@ -1261,9 +1295,9 @@ void gfs2_quota_cleanup(struct gfs2_sbd *sdp)
                 gfs2_lvb_unhold(qd->qd_gl);
                 kmem_cache_free(gfs2_quotad_cachep, qd);
 
-                spin_lock(&sdp->sd_quota_spin);
+                spin_lock(&qd_lru_lock);
         }
-        spin_unlock(&sdp->sd_quota_spin);
+        spin_unlock(&qd_lru_lock);
 
         gfs2_assert_warn(sdp, !atomic_read(&sdp->sd_quota_count));
 
@@ -1341,9 +1375,6 @@ int gfs2_quotad(void *data)
                 quotad_check_timeo(sdp, "sync", gfs2_quota_sync, t,
                                    &quotad_timeo, &tune->gt_quota_quantum);
 
-                /* FIXME: This should be turned into a shrinker */
-                gfs2_quota_scan(sdp);
-
                 /* Check for & recover partially truncated inodes */
                 quotad_check_trunc_list(sdp);
 
diff --git a/fs/gfs2/quota.h b/fs/gfs2/quota.h
index cec9032be97d..0fa5fa63d0e8 100644
--- a/fs/gfs2/quota.h
+++ b/fs/gfs2/quota.h
@@ -49,4 +49,6 @@ static inline int gfs2_quota_lock_check(struct gfs2_inode *ip)
         return ret;
 }
 
+extern int gfs2_shrink_qd_memory(int nr, gfp_t gfp_mask);
+
 #endif /* __QUOTA_DOT_H__ */
diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c
index 26c1fa777a95..a58a120dac92 100644
--- a/fs/gfs2/sys.c
+++ b/fs/gfs2/sys.c
@@ -373,7 +373,6 @@ TUNE_ATTR(complain_secs, 0);
 TUNE_ATTR(statfs_slow, 0);
 TUNE_ATTR(new_files_jdata, 0);
 TUNE_ATTR(quota_simul_sync, 1);
-TUNE_ATTR(quota_cache_secs, 1);
 TUNE_ATTR(stall_secs, 1);
 TUNE_ATTR(statfs_quantum, 1);
 TUNE_ATTR_DAEMON(recoverd_secs, recoverd_process);
@@ -389,7 +388,6 @@ static struct attribute *tune_attrs[] = {
         &tune_attr_complain_secs.attr,
         &tune_attr_statfs_slow.attr,
         &tune_attr_quota_simul_sync.attr,
-        &tune_attr_quota_cache_secs.attr,
         &tune_attr_stall_secs.attr,
         &tune_attr_statfs_quantum.attr,
         &tune_attr_recoverd_secs.attr,