ocfs2/dlm: dlm_is_lockres_migrateable() returns boolean

Patch cleans up the gunk added by commit 388c4bcb4e63e88fb1f312a2f5f9eb2623afcf5b.
dlm_is_lockres_migrateable() now returns 1 if lockresource is deemed
migrateable and 0 if not.

Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Joel Becker <jlbec@evilplan.org>

2 files changed, 63 insertions, 84 deletions

diff --git a/fs/ocfs2/dlm/dlmcommon.h b/fs/ocfs2/dlm/dlmcommon.h
index 4bdf7baee344..1aac42a29745 100644
--- a/fs/ocfs2/dlm/dlmcommon.h
+++ b/fs/ocfs2/dlm/dlmcommon.h
@@ -401,6 +401,18 @@ static inline int dlm_lvb_is_empty(char *lvb)
         return 1;
 }
 
+static inline char *dlm_list_in_text(enum dlm_lockres_list idx)
+{
+        if (idx == DLM_GRANTED_LIST)
+                return "granted";
+        else if (idx == DLM_CONVERTING_LIST)
+                return "converting";
+        else if (idx == DLM_BLOCKED_LIST)
+                return "blocked";
+        else
+                return "unknown";
+}
+
 static inline struct list_head *
 dlm_list_idx_to_ptr(struct dlm_lock_resource *res, enum dlm_lockres_list idx)
 {
diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index 84d166328cf7..ec4994628948 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -2339,65 +2339,55 @@ static void dlm_deref_lockres_worker(struct dlm_work_item *item, void *data)
         dlm_lockres_put(res);
 }
 
-/* Checks whether the lockres can be migrated. Returns 0 if yes, < 0
- * if not. If 0, numlocks is set to the number of locks in the lockres.
+/*
+ * A migrateable resource is one that is :
+ * 1. locally mastered, and,
+ * 2. zero local locks, and,
+ * 3. one or more non-local locks, or, one or more references
+ * Returns 1 if yes, 0 if not.
  */
 static int dlm_is_lockres_migrateable(struct dlm_ctxt *dlm,
-                                      struct dlm_lock_resource *res,
-                                      int *numlocks,
-                                      int *hasrefs)
+                                      struct dlm_lock_resource *res)
 {
-        int ret;
-        int i;
-        int count = 0;
+        enum dlm_lockres_list idx;
+        int nonlocal = 0, node_ref;
         struct list_head *queue;
         struct dlm_lock *lock;
+        u64 cookie;
 
         assert_spin_locked(&res->spinlock);
 
-        *numlocks = 0;
-        *hasrefs = 0;
-
-        ret = -EINVAL;
-        if (res->owner == DLM_LOCK_RES_OWNER_UNKNOWN) {
-                mlog(0, "cannot migrate lockres with unknown owner!\n");
-                goto leave;
-        }
-
-        if (res->owner != dlm->node_num) {
-                mlog(0, "cannot migrate lockres this node doesn't own!\n");
-                goto leave;
-        }
+        if (res->owner != dlm->node_num)
+                return 0;
 
-        ret = 0;
-        queue = &res->granted;
-        for (i = 0; i < 3; i++) {
+        for (idx = DLM_GRANTED_LIST; idx <= DLM_BLOCKED_LIST; idx++) {
+                queue = dlm_list_idx_to_ptr(res, idx);
                 list_for_each_entry(lock, queue, list) {
-                        ++count;
-                        if (lock->ml.node == dlm->node_num) {
-                                mlog(0, "found a lock owned by this node still "
-                                     "on the %s queue!  will not migrate this "
-                                     "lockres\n", (i == 0 ? "granted" :
-                                                   (i == 1 ? "converting" :
-                                                    "blocked")));
-                                ret = -ENOTEMPTY;
-                                goto leave;
+                        if (lock->ml.node != dlm->node_num) {
+                                nonlocal++;
+                                continue;
                         }
+                        cookie = be64_to_cpu(lock->ml.cookie);
+                        mlog(0, "%s: Not migrateable res %.*s, lock %u:%llu on "
+                             "%s list\n", dlm->name, res->lockname.len,
+                             res->lockname.name,
+                             dlm_get_lock_cookie_node(cookie),
+                             dlm_get_lock_cookie_seq(cookie),
+                             dlm_list_in_text(idx));
+                        return 0;
                 }
-                queue++;
         }
 
-        *numlocks = count;
-
-        count = find_next_bit(res->refmap, O2NM_MAX_NODES, 0);
-        if (count < O2NM_MAX_NODES)
-                *hasrefs = 1;
+        if (!nonlocal) {
+                node_ref = find_next_bit(res->refmap, O2NM_MAX_NODES, 0);
+                if (node_ref >= O2NM_MAX_NODES)
+                        return 0;
+        }
 
-        mlog(0, "%s: res %.*s, Migrateable, locks %d, refs %d\n", dlm->name,
-             res->lockname.len, res->lockname.name, *numlocks, *hasrefs);
+        mlog(0, "%s: res %.*s, Migrateable\n", dlm->name, res->lockname.len,
+             res->lockname.name);
 
-leave:
-        return ret;
+        return 1;
 }
 
 /*
@@ -2416,7 +2406,6 @@ static int dlm_migrate_lockres(struct dlm_ctxt *dlm,
         const char *name;
         unsigned int namelen;
         int mle_added = 0;
-        int numlocks, hasrefs;
         int wake = 0;
 
         if (!dlm_grab(dlm))
@@ -2427,19 +2416,13 @@ static int dlm_migrate_lockres(struct dlm_ctxt *dlm,
 
         mlog(0, "%s: Migrating %.*s to %u\n", dlm->name, namelen, name, target);
 
-        /*
-         * ensure this lockres is a proper candidate for migration
-         */
+        /* Ensure this lockres is a proper candidate for migration */
         spin_lock(&res->spinlock);
-        ret = dlm_is_lockres_migrateable(dlm, res, &numlocks, &hasrefs);
-        if (ret < 0) {
-                spin_unlock(&res->spinlock);
-                goto leave;
-        }
+        ret = dlm_is_lockres_migrateable(dlm, res);
         spin_unlock(&res->spinlock);
 
-        /* no work to do */
-        if (numlocks == 0 && !hasrefs)
+        /* No work to do */
+        if (!ret)
                 goto leave;
 
         /*
@@ -2658,44 +2641,35 @@ leave:
 
         dlm_put(dlm);
 
-        mlog(0, "returning %d\n", ret);
+        mlog(0, "%s: Migrating %.*s to %u, returns %d\n", dlm->name, namelen,
+             name, target, ret);
         return ret;
 }
 
 #define DLM_MIGRATION_RETRY_MS  100
 
-/* Should be called only after beginning the domain leave process.
+/*
+ * Should be called only after beginning the domain leave process.
  * There should not be any remaining locks on nonlocal lock resources,
  * and there should be no local locks left on locally mastered resources.
  *
  * Called with the dlm spinlock held, may drop it to do migration, but
  * will re-acquire before exit.
  *
- * Returns: 1 if dlm->spinlock was dropped/retaken, 0 if never dropped */
+ * Returns: 1 if dlm->spinlock was dropped/retaken, 0 if never dropped
+ */
 int dlm_empty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
 {
-        int ret;
+        int mig, ret;
         int lock_dropped = 0;
-        int numlocks, hasrefs;
 
-        spin_lock(&res->spinlock);
-        if (res->owner != dlm->node_num) {
-                if (!__dlm_lockres_unused(res)) {
-                        mlog(ML_ERROR, "%s:%.*s: this node is not master, "
-                             "trying to free this but locks remain\n",
-                             dlm->name, res->lockname.len, res->lockname.name);
-                }
-                spin_unlock(&res->spinlock);
-                goto leave;
-        }
+        assert_spin_locked(&dlm->spinlock);
 
-        /* No need to migrate a lockres having no locks */
-        ret = dlm_is_lockres_migrateable(dlm, res, &numlocks, &hasrefs);
-        if (ret >= 0 && numlocks == 0 && !hasrefs) {
-                spin_unlock(&res->spinlock);
-                goto leave;
-        }
+        spin_lock(&res->spinlock);
+        mig = dlm_is_lockres_migrateable(dlm, res);
         spin_unlock(&res->spinlock);
+        if (!mig)
+                goto leave;
 
         /* Wheee! Migrate lockres here! Will sleep so drop spinlock. */
         spin_unlock(&dlm->spinlock);
@@ -2704,15 +2678,8 @@ int dlm_empty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
                 ret = dlm_migrate_lockres(dlm, res, O2NM_MAX_NODES);
                 if (ret >= 0)
                         break;
-                if (ret == -ENOTEMPTY) {
-                        mlog(ML_ERROR, "lockres %.*s still has local locks!\n",
-                                res->lockname.len, res->lockname.name);
-                        BUG();
-                }
-
-                mlog(0, "lockres %.*s: migrate failed, "
-                     "retrying\n", res->lockname.len,
-                     res->lockname.name);
+                mlog(0, "%s: res %.*s, Migrate failed, retrying\n", dlm->name,
+                     res->lockname.len, res->lockname.name);
                 msleep(DLM_MIGRATION_RETRY_MS);
         }
         spin_lock(&dlm->spinlock);