block: autoconvert trivial BKL users to private mutex

The block device drivers have all gained new lock_kernel
calls from a recent pushdown, and some of the drivers
were already using the BKL before.

This turns the BKL into a set of per-driver mutexes.
Still need to check whether this is safe to do.

file=$1
name=$2
if grep -q lock_kernel ${file} ; then
    if grep -q 'include.*linux.mutex.h' ${file} ; then
            sed -i '/include.*<linux\/smp_lock.h>/d' ${file}
    else
            sed -i 's/include.*<linux\/smp_lock.h>.*$/include <linux\/mutex.h>/g' ${file}
    fi
    sed -i ${file} \
        -e "/^#include.*linux.mutex.h/,$ {
                1,/^\(static\|int\|long\)/ {
                     /^\(static\|int\|long\)/istatic DEFINE_MUTEX(${name}_mutex);

} }"  \
    -e "s/\(un\)*lock_kernel\>[ ]*()/mutex_\1lock(\&${name}_mutex)/g" \
    -e '/[      ]*cycle_kernel_lock();/d'
else
    sed -i -e '/include.*\<smp_lock.h\>/d' ${file}  \
                -e '/cycle_kernel_lock()/d'
fi

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/block/loop.c

@@ -67,7 +67,7 @@
 #include <linux/compat.h>
 #include <linux/suspend.h>
 #include <linux/freezer.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/writeback.h>
 #include <linux/buffer_head.h>		/* for invalidate_bdev() */
 #include <linux/completion.h>
@@ -77,6 +77,7 @@
 
 #include <asm/uaccess.h>
 
+static DEFINE_MUTEX(loop_mutex);
 static LIST_HEAD(loop_devices);
 static DEFINE_MUTEX(loop_devices_mutex);
 
@@ -1409,11 +1410,11 @@ static int lo_open(struct block_device *bdev, fmode_t mode)
 {
 	struct loop_device *lo = bdev->bd_disk->private_data;
 
-	lock_kernel();
+	mutex_lock(&loop_mutex);
 	mutex_lock(&lo->lo_ctl_mutex);
 	lo->lo_refcnt++;
 	mutex_unlock(&lo->lo_ctl_mutex);
-	unlock_kernel();
+	mutex_unlock(&loop_mutex);
 
 	return 0;
 }
@@ -1423,7 +1424,7 @@ static int lo_release(struct gendisk *disk, fmode_t mode)
 	struct loop_device *lo = disk->private_data;
 	int err;
 
-	lock_kernel();
+	mutex_lock(&loop_mutex);
 	mutex_lock(&lo->lo_ctl_mutex);
 
 	if (--lo->lo_refcnt)
@@ -1448,7 +1449,7 @@ static int lo_release(struct gendisk *disk, fmode_t mode)
 out:
 	mutex_unlock(&lo->lo_ctl_mutex);
 out_unlocked:
-	lock_kernel();
+	mutex_unlock(&loop_mutex);
 	return 0;
 }