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/brd.c

@@ -15,7 +15,7 @@
 #include <linux/blkdev.h>
 #include <linux/bio.h>
 #include <linux/highmem.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/radix-tree.h>
 #include <linux/buffer_head.h> /* invalidate_bh_lrus() */
 #include <linux/slab.h>
@@ -55,6 +55,7 @@ struct brd_device {
 /*
  * Look up and return a brd's page for a given sector.
  */
+static DEFINE_MUTEX(brd_mutex);
 static struct page *brd_lookup_page(struct brd_device *brd, sector_t sector)
 {
 	pgoff_t idx;
@@ -402,7 +403,7 @@ static int brd_ioctl(struct block_device *bdev, fmode_t mode,
 	 * ram device BLKFLSBUF has special semantics, we want to actually
 	 * release and destroy the ramdisk data.
 	 */
-	lock_kernel();
+	mutex_lock(&brd_mutex);
 	mutex_lock(&bdev->bd_mutex);
 	error = -EBUSY;
 	if (bdev->bd_openers <= 1) {
@@ -419,7 +420,7 @@ static int brd_ioctl(struct block_device *bdev, fmode_t mode,
 		error = 0;
 	}
 	mutex_unlock(&bdev->bd_mutex);
-	unlock_kernel();
+	mutex_unlock(&brd_mutex);
 
 	return error;
 }