1 files changed, 128 insertions, 36 deletions

diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 4e97dcc..b3068ad 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -55,7 +55,6 @@
 #include "slot_map.h"
 #include "super.h"
 #include "uptodate.h"
-#include "vote.h"
 
 #include "buffer_head_io.h"
 
@@ -153,10 +152,10 @@ struct ocfs2_lock_res_ops {
 	struct ocfs2_super * (*get_osb)(struct ocfs2_lock_res *);
 
 	/*
-	 * Optionally called in the downconvert (or "vote") thread
-	 * after a successful downconvert. The lockres will not be
-	 * referenced after this callback is called, so it is safe to
-	 * free memory, etc.
+	 * Optionally called in the downconvert thread after a
+	 * successful downconvert. The lockres will not be referenced
+	 * after this callback is called, so it is safe to free
+	 * memory, etc.
 	 *
 	 * The exact semantics of when this is called are controlled
 	 * by ->downconvert_worker()
@@ -310,8 +309,9 @@ static inline void ocfs2_recover_from_dlm_error(struct ocfs2_lock_res *lockres,
 		"resource %s: %s\n", dlm_errname(_stat), _func,	\
 		_lockres->l_name, dlm_errmsg(_stat));		\
 } while (0)
-static void ocfs2_vote_on_unlock(struct ocfs2_super *osb,
-				 struct ocfs2_lock_res *lockres);
+static int ocfs2_downconvert_thread(void *arg);
+static void ocfs2_downconvert_on_unlock(struct ocfs2_super *osb,
+					struct ocfs2_lock_res *lockres);
 static int ocfs2_meta_lock_update(struct inode *inode,
 				  struct buffer_head **bh);
 static void ocfs2_drop_osb_locks(struct ocfs2_super *osb);
@@ -732,7 +732,7 @@ static void ocfs2_blocking_ast(void *opaque, int level)
 
 	wake_up(&lockres->l_event);
 
-	ocfs2_kick_vote_thread(osb);
+	ocfs2_wake_downconvert_thread(osb);
 }
 
 static void ocfs2_locking_ast(void *opaque)
@@ -1089,7 +1089,7 @@ static void ocfs2_cluster_unlock(struct ocfs2_super *osb,
 	mlog_entry_void();
 	spin_lock_irqsave(&lockres->l_lock, flags);
 	ocfs2_dec_holders(lockres, level);
-	ocfs2_vote_on_unlock(osb, lockres);
+	ocfs2_downconvert_on_unlock(osb, lockres);
 	spin_unlock_irqrestore(&lockres->l_lock, flags);
 	mlog_exit_void();
 }
@@ -1372,15 +1372,15 @@ int ocfs2_data_lock_with_page(struct inode *inode,
 	return ret;
 }
 
-static void ocfs2_vote_on_unlock(struct ocfs2_super *osb,
-				 struct ocfs2_lock_res *lockres)
+static void ocfs2_downconvert_on_unlock(struct ocfs2_super *osb,
+					struct ocfs2_lock_res *lockres)
 {
 	int kick = 0;
 
 	mlog_entry_void();
 
 	/* If we know that another node is waiting on our lock, kick
-	 * the vote thread * pre-emptively when we reach a release
+	 * the downconvert thread * pre-emptively when we reach a release
 	 * condition. */
 	if (lockres->l_flags & OCFS2_LOCK_BLOCKED) {
 		switch(lockres->l_blocking) {
@@ -1398,7 +1398,7 @@ static void ocfs2_vote_on_unlock(struct ocfs2_super *osb,
 	}
 
 	if (kick)
-		ocfs2_kick_vote_thread(osb);
+		ocfs2_wake_downconvert_thread(osb);
 
 	mlog_exit_void();
 }
@@ -1832,19 +1832,20 @@ bail:
 }
 
 /*
- * This is working around a lock inversion between tasks acquiring DLM locks
- * while holding a page lock and the vote thread which blocks dlm lock acquiry
- * while acquiring page locks.
+ * This is working around a lock inversion between tasks acquiring DLM
+ * locks while holding a page lock and the downconvert thread which
+ * blocks dlm lock acquiry while acquiring page locks.
  *
  * ** These _with_page variantes are only intended to be called from aop
  * methods that hold page locks and return a very specific *positive* error
  * code that aop methods pass up to the VFS -- test for errors with != 0. **
  *
- * The DLM is called such that it returns -EAGAIN if it would have blocked
- * waiting for the vote thread.  In that case we unlock our page so the vote
- * thread can make progress.  Once we've done this we have to return
- * AOP_TRUNCATED_PAGE so the aop method that called us can bubble that back up
- * into the VFS who will then immediately retry the aop call.
+ * The DLM is called such that it returns -EAGAIN if it would have
+ * blocked waiting for the downconvert thread.  In that case we unlock
+ * our page so the downconvert thread can make progress.  Once we've
+ * done this we have to return AOP_TRUNCATED_PAGE so the aop method
+ * that called us can bubble that back up into the VFS who will then
+ * immediately retry the aop call.
  *
  * We do a blocking lock and immediate unlock before returning, though, so that
  * the lock has a great chance of being cached on this node by the time the VFS
@@ -2320,11 +2321,11 @@ int ocfs2_dlm_init(struct ocfs2_super *osb)
 		goto bail;
 	}
 
-	/* launch vote thread */
-	osb->vote_task = kthread_run(ocfs2_vote_thread, osb, "ocfs2vote");
-	if (IS_ERR(osb->vote_task)) {
-		status = PTR_ERR(osb->vote_task);
-		osb->vote_task = NULL;
+	/* launch downconvert thread */
+	osb->dc_task = kthread_run(ocfs2_downconvert_thread, osb, "ocfs2dc");
+	if (IS_ERR(osb->dc_task)) {
+		status = PTR_ERR(osb->dc_task);
+		osb->dc_task = NULL;
 		mlog_errno(status);
 		goto bail;
 	}
@@ -2353,8 +2354,8 @@ local:
 bail:
 	if (status < 0) {
 		ocfs2_dlm_shutdown_debug(osb);
-		if (osb->vote_task)
-			kthread_stop(osb->vote_task);
+		if (osb->dc_task)
+			kthread_stop(osb->dc_task);
 	}
 
 	mlog_exit(status);
@@ -2369,9 +2370,9 @@ void ocfs2_dlm_shutdown(struct ocfs2_super *osb)
 
 	ocfs2_drop_osb_locks(osb);
 
-	if (osb->vote_task) {
-		kthread_stop(osb->vote_task);
-		osb->vote_task = NULL;
+	if (osb->dc_task) {
+		kthread_stop(osb->dc_task);
+		osb->dc_task = NULL;
 	}
 
 	ocfs2_lock_res_free(&osb->osb_super_lockres);
@@ -2527,7 +2528,7 @@ out:
 
 /* Mark the lockres as being dropped. It will no longer be
  * queued if blocking, but we still may have to wait on it
- * being dequeued from the vote thread before we can consider
+ * being dequeued from the downconvert thread before we can consider
  * it safe to drop. 
  *
  * You can *not* attempt to call cluster_lock on this lockres anymore. */
@@ -2903,7 +2904,7 @@ static void ocfs2_set_meta_lvb(struct ocfs2_lock_res *lockres)
 
 /*
  * Does the final reference drop on our dentry lock. Right now this
- * happens in the vote thread, but we could choose to simplify the
+ * happens in the downconvert thread, but we could choose to simplify the
  * dlmglue API and push these off to the ocfs2_wq in the future.
  */
 static void ocfs2_dentry_post_unlock(struct ocfs2_super *osb,
@@ -3042,7 +3043,7 @@ void ocfs2_process_blocked_lock(struct ocfs2_super *osb,
 	mlog(0, "lockres %s blocked.\n", lockres->l_name);
 
 	/* Detect whether a lock has been marked as going away while
-	 * the vote thread was processing other things. A lock can
+	 * the downconvert thread was processing other things. A lock can
 	 * still be marked with OCFS2_LOCK_FREEING after this check,
 	 * but short circuiting here will still save us some
 	 * performance. */
@@ -3091,13 +3092,104 @@ static void ocfs2_schedule_blocked_lock(struct ocfs2_super *osb,
 
 	lockres_or_flags(lockres, OCFS2_LOCK_QUEUED);
 
-	spin_lock(&osb->vote_task_lock);
+	spin_lock(&osb->dc_task_lock);
 	if (list_empty(&lockres->l_blocked_list)) {
 		list_add_tail(&lockres->l_blocked_list,
 			      &osb->blocked_lock_list);
 		osb->blocked_lock_count++;
 	}
-	spin_unlock(&osb->vote_task_lock);
+	spin_unlock(&osb->dc_task_lock);
 
 	mlog_exit_void();
 }
+
+static void ocfs2_downconvert_thread_do_work(struct ocfs2_super *osb)
+{
+	unsigned long processed;
+	struct ocfs2_lock_res *lockres;
+
+	mlog_entry_void();
+
+	spin_lock(&osb->dc_task_lock);
+	/* grab this early so we know to try again if a state change and
+	 * wake happens part-way through our work  */
+	osb->dc_work_sequence = osb->dc_wake_sequence;
+
+	processed = osb->blocked_lock_count;
+	while (processed) {
+		BUG_ON(list_empty(&osb->blocked_lock_list));
+
+		lockres = list_entry(osb->blocked_lock_list.next,
+				     struct ocfs2_lock_res, l_blocked_list);
+		list_del_init(&lockres->l_blocked_list);
+		osb->blocked_lock_count--;
+		spin_unlock(&osb->dc_task_lock);
+
+		BUG_ON(!processed);
+		processed--;
+
+		ocfs2_process_blocked_lock(osb, lockres);
+
+		spin_lock(&osb->dc_task_lock);
+	}
+	spin_unlock(&osb->dc_task_lock);
+
+	mlog_exit_void();
+}
+
+static int ocfs2_downconvert_thread_lists_empty(struct ocfs2_super *osb)
+{
+	int empty = 0;
+
+	spin_lock(&osb->dc_task_lock);
+	if (list_empty(&osb->blocked_lock_list))
+		empty = 1;
+
+	spin_unlock(&osb->dc_task_lock);
+	return empty;
+}
+
+static int ocfs2_downconvert_thread_should_wake(struct ocfs2_super *osb)
+{
+	int should_wake = 0;
+
+	spin_lock(&osb->dc_task_lock);
+	if (osb->dc_work_sequence != osb->dc_wake_sequence)
+		should_wake = 1;
+	spin_unlock(&osb->dc_task_lock);
+
+	return should_wake;
+}
+
+int ocfs2_downconvert_thread(void *arg)
+{
+	int status = 0;
+	struct ocfs2_super *osb = arg;
+
+	/* only quit once we've been asked to stop and there is no more
+	 * work available */
+	while (!(kthread_should_stop() &&
+		ocfs2_downconvert_thread_lists_empty(osb))) {
+
+		wait_event_interruptible(osb->dc_event,
+					 ocfs2_downconvert_thread_should_wake(osb) ||
+					 kthread_should_stop());
+
+		mlog(0, "downconvert_thread: awoken\n");
+
+		ocfs2_downconvert_thread_do_work(osb);
+	}
+
+	osb->dc_task = NULL;
+	return status;
+}
+
+void ocfs2_wake_downconvert_thread(struct ocfs2_super *osb)
+{
+	spin_lock(&osb->dc_task_lock);
+	/* make sure the voting thread gets a swipe at whatever changes
+	 * the caller may have made to the voting state */
+	osb->dc_wake_sequence++;
+	spin_unlock(&osb->dc_task_lock);
+	wake_up(&osb->dc_event);
+}