mtd: Remove redundant mutex from mtd_blkdevs.c

In commit 2a48fc0a ('block: autoconvert
trivial BKL users to private mutex'), Arnd replaced the BKL usage with a
mutex. However, Maxim has already provided a better fix in commit
480792b7 ('mtd: blktrans: kill BKL'),
which was simply to remove the BKL without replacing it — since he'd
already made it do all necessary locking for itself.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/mtd_blkdevs.c

@@ -37,7 +37,6 @@
 
 #include "mtdcore.h"
 
-static DEFINE_MUTEX(mtd_blkdevs_mutex);
 static LIST_HEAD(blktrans_majors);
 static DEFINE_MUTEX(blktrans_ref_mutex);
 
@@ -185,7 +184,6 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode)
 	if (!dev)
 		return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 
-	mutex_lock(&mtd_blkdevs_mutex);
 	mutex_lock(&dev->lock);
 
 	if (dev->open++)
@@ -202,7 +200,6 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode)
 unlock:
 	mutex_unlock(&dev->lock);
 	blktrans_dev_put(dev);
-	mutex_unlock(&mtd_blkdevs_mutex);
 	return ret;
 }
 
@@ -214,7 +211,6 @@ static int blktrans_release(struct gendisk *disk, fmode_t mode)
 	if (!dev)
 		return ret;
 
-	mutex_lock(&mtd_blkdevs_mutex);
 	mutex_lock(&dev->lock);
 
 	if (--dev->open)
@@ -230,7 +226,6 @@ static int blktrans_release(struct gendisk *disk, fmode_t mode)
 unlock:
 	mutex_unlock(&dev->lock);
 	blktrans_dev_put(dev);
-	mutex_unlock(&mtd_blkdevs_mutex);
 	return ret;
 }
 
@@ -263,7 +258,6 @@ static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 	if (!dev)
 		return ret;
 
-	mutex_lock(&mtd_blkdevs_mutex);
 	mutex_lock(&dev->lock);
 
 	if (!dev->mtd)
@@ -278,7 +272,6 @@ static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 	}
 unlock:
 	mutex_unlock(&dev->lock);
-	mutex_unlock(&mtd_blkdevs_mutex);
 	blktrans_dev_put(dev);
 	return ret;
 }