drbd-convert-bitmap-from-semaphore-to-mutex.patch

From 085043eb5bfd10eb0866ced0983f66b7f3548260 Mon Sep 17 00:00:00 2001
From: Paul Gortmaker <paul.gortmaker@windriver.com>
Date: Sun, 23 Jan 2011 16:12:49 -0500
Subject: [PATCH] drbd: convert bitmap from semaphore to mutex

This is one of several extractions from the merge up to 33-rc8.

See it in a git tip repo with:

   git diff 5f854cfc024622e4aae14d7cf422f6ff86278688^2 \
	5f854cfc024622e4aae14d7cf422f6ff86278688 \
	drivers/block/drbd/drbd_bitmap.c

You can find the origin of this change in the tip merge commit:

     commit 5f854cfc024622e4aae14d7cf422f6ff86278688
     Merge: cc24da0 4ec62b2
     Author: Thomas Gleixner <tglx@linutronix.de>
     Date:   Sun Feb 21 20:17:22 2010 +0100

         Forward to 2.6.33-rc8

         Merge branch 'linus' into rt/head with a pile of conflicts.

         Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Normally there are not significant changes/additions in a merge commit that
are not from any other "normal" commit.  But in this case there are, so
break them out into separate explicit commits.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/block/drbd/drbd_bitmap.c b/drivers/block/drbd/drbd_bitmap.c
index b61057e..f58e765 100644
--- a/drivers/block/drbd/drbd_bitmap.c
+++ b/drivers/block/drbd/drbd_bitmap.c
@@ -66,7 +66,7 @@ struct drbd_bitmap {
 	size_t   bm_words;
 	size_t   bm_number_of_pages;
 	sector_t bm_dev_capacity;
-	struct semaphore bm_change; /* serializes resize operations */
+	struct mutex bm_change; /* serializes resize operations */
 
 	atomic_t bm_async_io;
 	wait_queue_head_t bm_io_wait;
@@ -114,7 +114,7 @@ void drbd_bm_lock(struct drbd_conf *mdev, char *why)
 		return;
 	}
 
-	trylock_failed = down_trylock(&b->bm_change);
+	trylock_failed = !mutex_trylock(&b->bm_change);
 
 	if (trylock_failed) {
 		dev_warn(DEV, "%s going to '%s' but bitmap already locked for '%s' by %s\n",
@@ -125,7 +125,7 @@ void drbd_bm_lock(struct drbd_conf *mdev, char *why)
 		    b->bm_task == mdev->receiver.task ? "receiver" :
 		    b->bm_task == mdev->asender.task  ? "asender"  :
 		    b->bm_task == mdev->worker.task   ? "worker"   : "?");
-		down(&b->bm_change);
+		mutex_lock(&b->bm_change);
 	}
 	if (__test_and_set_bit(BM_LOCKED, &b->bm_flags))
 		dev_err(DEV, "FIXME bitmap already locked in bm_lock\n");
@@ -147,7 +147,7 @@ void drbd_bm_unlock(struct drbd_conf *mdev)
 
 	b->bm_why  = NULL;
 	b->bm_task = NULL;
-	up(&b->bm_change);
+	mutex_unlock(&b->bm_change);
 }
 
 /* word offset to long pointer */
@@ -295,7 +295,7 @@ int drbd_bm_init(struct drbd_conf *mdev)
 	if (!b)
 		return -ENOMEM;
 	spin_lock_init(&b->bm_lock);
-	init_MUTEX(&b->bm_change);
+	mutex_init(&b->bm_change);
 	init_waitqueue_head(&b->bm_io_wait);
 
 	mdev->bitmap = b;
-- 
1.7.1.1