block: push down BKL into .open and .release

The open and release block_device_operations are currently
called with the BKL held. In order to change that, we must
first make sure that all drivers that currently rely
on this have no regressions.

This blindly pushes the BKL into all .open and .release
operations for all block drivers to prepare for the
next step. The drivers can subsequently replace the BKL
with their own locks or remove it completely when it can
be shown that it is not needed.

The functions blkdev_get and blkdev_put are the only
remaining users of the big kernel lock in the block
layer, besides a few uses in the ioctl code, none
of which need to serialize with blkdev_{get,put}.

Most of these two functions is also under the protection
of bdev->bd_mutex, including the actual calls to
->open and ->release, and the common code does not
access any global data structures that need the BKL.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

20 files changed, 207 insertions, 26 deletions

diff --git a/drivers/block/DAC960.c b/drivers/block/DAC960.c
index c5f22bb0a48e..4e2c367fec11 100644
--- a/drivers/block/DAC960.c
+++ b/drivers/block/DAC960.c
@@ -79,23 +79,28 @@ static int DAC960_open(struct block_device *bdev, fmode_t mode)
         struct gendisk *disk = bdev->bd_disk;
         DAC960_Controller_T *p = disk->queue->queuedata;
         int drive_nr = (long)disk->private_data;
+        int ret = -ENXIO;
 
+        lock_kernel();
         if (p->FirmwareType == DAC960_V1_Controller) {
                 if (p->V1.LogicalDriveInformation[drive_nr].
                     LogicalDriveState == DAC960_V1_LogicalDrive_Offline)
-                        return -ENXIO;
+                        goto out;
         } else {
                 DAC960_V2_LogicalDeviceInfo_T *i =
                         p->V2.LogicalDeviceInformation[drive_nr];
                 if (!i || i->LogicalDeviceState == DAC960_V2_LogicalDevice_Offline)
-                        return -ENXIO;
+                        goto out;
         }
 
         check_disk_change(bdev);
 
         if (!get_capacity(p->disks[drive_nr]))
-                return -ENXIO;
-        return 0;
+                goto out;
+        ret = 0;
+out:
+        unlock_kernel();
+        return ret;
 }
 
 static int DAC960_getgeo(struct block_device *bdev, struct hd_geometry *geo)
diff --git a/drivers/block/amiflop.c b/drivers/block/amiflop.c
index 0fa26359304c..76f114f0bba3 100644
--- a/drivers/block/amiflop.c
+++ b/drivers/block/amiflop.c
@@ -1555,10 +1555,13 @@ static int floppy_open(struct block_device *bdev, fmode_t mode)
         int old_dev;
         unsigned long flags;
 
+        lock_kernel();
         old_dev = fd_device[drive];
 
-        if (fd_ref[drive] && old_dev != system)
+        if (fd_ref[drive] && old_dev != system) {
+                unlock_kernel();
                 return -EBUSY;
+        }
 
         if (mode & (FMODE_READ|FMODE_WRITE)) {
                 check_disk_change(bdev);
@@ -1571,8 +1574,10 @@ static int floppy_open(struct block_device *bdev, fmode_t mode)
                         fd_deselect (drive);
                         rel_fdc();
 
-                        if (wrprot)
+                        if (wrprot) {
+                                unlock_kernel();
                                 return -EROFS;
+                        }
                 }
         }
 
@@ -1589,6 +1594,7 @@ static int floppy_open(struct block_device *bdev, fmode_t mode)
         printk(KERN_INFO "fd%d: accessing %s-disk with %s-layout\n",drive,
                unit[drive].type->name, data_types[system].name);
 
+        unlock_kernel();
         return 0;
 }
 
@@ -1597,6 +1603,7 @@ static int floppy_release(struct gendisk *disk, fmode_t mode)
         struct amiga_floppy_struct *p = disk->private_data;
         int drive = p - unit;
 
+        lock_kernel();
         if (unit[drive].dirty == 1) {
                 del_timer (flush_track_timer + drive);
                 non_int_flush_track (drive);
@@ -1610,6 +1617,7 @@ static int floppy_release(struct gendisk *disk, fmode_t mode)
 /* the mod_use counter is handled this way */
         floppy_off (drive | 0x40000000);
 #endif
+        unlock_kernel();
         return 0;
 }
 
diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c
index 65deffde60ac..a946929735a5 100644
--- a/drivers/block/aoe/aoeblk.c
+++ b/drivers/block/aoe/aoeblk.c
@@ -12,6 +12,7 @@
 #include <linux/slab.h>
 #include <linux/genhd.h>
 #include <linux/netdevice.h>
+#include <linux/smp_lock.h>
 #include "aoe.h"
 
 static struct kmem_cache *buf_pool_cache;
@@ -124,13 +125,16 @@ aoeblk_open(struct block_device *bdev, fmode_t mode)
         struct aoedev *d = bdev->bd_disk->private_data;
         ulong flags;
 
+        lock_kernel();
         spin_lock_irqsave(&d->lock, flags);
         if (d->flags & DEVFL_UP) {
                 d->nopen++;
                 spin_unlock_irqrestore(&d->lock, flags);
+                unlock_kernel();
                 return 0;
         }
         spin_unlock_irqrestore(&d->lock, flags);
+        unlock_kernel();
         return -ENODEV;
 }
 
diff --git a/drivers/block/ataflop.c b/drivers/block/ataflop.c
index 1bb8bfcfdbd9..aceb96476524 100644
--- a/drivers/block/ataflop.c
+++ b/drivers/block/ataflop.c
@@ -1850,22 +1850,34 @@ static int floppy_open(struct block_device *bdev, fmode_t mode)
         return 0;
 }
 
+static int floppy_unlocked_open(struct block_device *bdev, fmode_t mode)
+{
+        int ret;
+
+        lock_kernel();
+        ret = floppy_open(bdev, mode);
+        unlock_kernel();
+
+        return ret;
+}
 
 static int floppy_release(struct gendisk *disk, fmode_t mode)
 {
         struct atari_floppy_struct *p = disk->private_data;
+        lock_kernel();
         if (p->ref < 0)
                 p->ref = 0;
         else if (!p->ref--) {
                 printk(KERN_ERR "floppy_release with fd_ref == 0");
                 p->ref = 0;
         }
+        unlock_kernel();
         return 0;
 }
 
 static const struct block_device_operations floppy_fops = {
         .owner          = THIS_MODULE,
-        .open           = floppy_open,
+        .open           = floppy_unlocked_open,
         .release        = floppy_release,
         .ioctl          = fd_ioctl,
         .media_changed  = check_floppy_change,
diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index a6c0494dd054..665a470310a9 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -178,6 +178,7 @@ static void do_cciss_request(struct request_queue *q);
 static irqreturn_t do_cciss_intx(int irq, void *dev_id);
 static irqreturn_t do_cciss_msix_intr(int irq, void *dev_id);
 static int cciss_open(struct block_device *bdev, fmode_t mode);
+static int cciss_unlocked_open(struct block_device *bdev, fmode_t mode);
 static int cciss_release(struct gendisk *disk, fmode_t mode);
 static int do_ioctl(struct block_device *bdev, fmode_t mode,
                     unsigned int cmd, unsigned long arg);
@@ -237,7 +238,7 @@ static int cciss_compat_ioctl(struct block_device *, fmode_t,
 
 static const struct block_device_operations cciss_fops = {
         .owner = THIS_MODULE,
-        .open = cciss_open,
+        .open = cciss_unlocked_open,
         .release = cciss_release,
         .ioctl = do_ioctl,
         .getgeo = cciss_getgeo,
@@ -1042,13 +1043,28 @@ static int cciss_open(struct block_device *bdev, fmode_t mode)
         return 0;
 }
 
+static int cciss_unlocked_open(struct block_device *bdev, fmode_t mode)
+{
+        int ret;
+
+        lock_kernel();
+        ret = cciss_open(bdev, mode);
+        unlock_kernel();
+
+        return ret;
+}
+
 /*
  * Close.  Sync first.
  */
 static int cciss_release(struct gendisk *disk, fmode_t mode)
 {
-        ctlr_info_t *host = get_host(disk);
-        drive_info_struct *drv = get_drv(disk);
+        ctlr_info_t *host;
+        drive_info_struct *drv;
+
+        lock_kernel();
+        host = get_host(disk);
+        drv = get_drv(disk);
 
 #ifdef CCISS_DEBUG
         printk(KERN_DEBUG "cciss_release %s\n", disk->disk_name);
@@ -1056,6 +1072,7 @@ static int cciss_release(struct gendisk *disk, fmode_t mode)
 
         drv->usage_count--;
         host->usage_count--;
+        unlock_kernel();
         return 0;
 }
 
diff --git a/drivers/block/cpqarray.c b/drivers/block/cpqarray.c
index c459aeea3c0c..28937b661564 100644
--- a/drivers/block/cpqarray.c
+++ b/drivers/block/cpqarray.c
@@ -158,7 +158,7 @@ static int sendcmd(
         unsigned int blkcnt,
         unsigned int log_unit );
 
-static int ida_open(struct block_device *bdev, fmode_t mode);
+static int ida_unlocked_open(struct block_device *bdev, fmode_t mode);
 static int ida_release(struct gendisk *disk, fmode_t mode);
 static int ida_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg);
 static int ida_getgeo(struct block_device *bdev, struct hd_geometry *geo);
@@ -196,7 +196,7 @@ static inline ctlr_info_t *get_host(struct gendisk *disk)
 
 static const struct block_device_operations ida_fops  = {
         .owner          = THIS_MODULE,
-        .open           = ida_open,
+        .open           = ida_unlocked_open,
         .release        = ida_release,
         .ioctl          = ida_ioctl,
         .getgeo         = ida_getgeo,
@@ -841,13 +841,29 @@ static int ida_open(struct block_device *bdev, fmode_t mode)
         return 0;
 }
 
+static int ida_unlocked_open(struct block_device *bdev, fmode_t mode)
+{
+        int ret;
+
+        lock_kernel();
+        ret = ida_open(bdev, mode);
+        unlock_kernel();
+
+        return ret;
+}
+
 /*
  * Close.  Sync first.
  */
 static int ida_release(struct gendisk *disk, fmode_t mode)
 {
-        ctlr_info_t *host = get_host(disk);
+        ctlr_info_t *host;
+
+        lock_kernel();
+        host = get_host(disk);
         host->usage_count--;
+        unlock_kernel();
+
         return 0;
 }
 
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index e2ab13d99d69..d2b6764a7b1f 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -2604,6 +2604,7 @@ static int drbd_open(struct block_device *bdev, fmode_t mode)
         unsigned long flags;
         int rv = 0;
 
+        lock_kernel();
         spin_lock_irqsave(&mdev->req_lock, flags);
         /* to have a stable mdev->state.role
          * and no race with updating open_cnt */
@@ -2618,6 +2619,7 @@ static int drbd_open(struct block_device *bdev, fmode_t mode)
         if (!rv)
                 mdev->open_cnt++;
         spin_unlock_irqrestore(&mdev->req_lock, flags);
+        unlock_kernel();
 
         return rv;
 }
@@ -2625,7 +2627,9 @@ static int drbd_open(struct block_device *bdev, fmode_t mode)
 static int drbd_release(struct gendisk *gd, fmode_t mode)
 {
         struct drbd_conf *mdev = gd->private_data;
+        lock_kernel();
         mdev->open_cnt--;
+        unlock_kernel();
         return 0;
 }
 
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 40419b066aa9..3126d5122b2b 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -3616,6 +3616,7 @@ static int floppy_release(struct gendisk *disk, fmode_t mode)
 {
         int drive = (long)disk->private_data;
 
+        lock_kernel();
         mutex_lock(&open_lock);
         if (UDRS->fd_ref < 0)
                 UDRS->fd_ref = 0;
@@ -3626,6 +3627,7 @@ static int floppy_release(struct gendisk *disk, fmode_t mode)
         if (!UDRS->fd_ref)
                 opened_bdev[drive] = NULL;
         mutex_unlock(&open_lock);
+        unlock_kernel();
 
         return 0;
 }
@@ -3643,6 +3645,7 @@ static int floppy_open(struct block_device *bdev, fmode_t mode)
         int res = -EBUSY;
         char *tmp;
 
+        lock_kernel();
         mutex_lock(&open_lock);
         old_dev = UDRS->fd_device;
         if (opened_bdev[drive] && opened_bdev[drive] != bdev)
@@ -3719,6 +3722,7 @@ static int floppy_open(struct block_device *bdev, fmode_t mode)
                         goto out;
         }
         mutex_unlock(&open_lock);
+        unlock_kernel();
         return 0;
 out:
         if (UDRS->fd_ref < 0)
@@ -3729,6 +3733,7 @@ out:
                 opened_bdev[drive] = NULL;
 out2:
         mutex_unlock(&open_lock);
+        unlock_kernel();
         return res;
 }
 
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index d285a5481965..f3c636d23718 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -67,6 +67,7 @@
 #include <linux/compat.h>
 #include <linux/suspend.h>
 #include <linux/freezer.h>
+#include <linux/smp_lock.h>
 #include <linux/writeback.h>
 #include <linux/buffer_head.h>          /* for invalidate_bdev() */
 #include <linux/completion.h>
@@ -1408,9 +1409,11 @@ static int lo_open(struct block_device *bdev, fmode_t mode)
 {
         struct loop_device *lo = bdev->bd_disk->private_data;
 
+        lock_kernel();
         mutex_lock(&lo->lo_ctl_mutex);
         lo->lo_refcnt++;
         mutex_unlock(&lo->lo_ctl_mutex);
+        unlock_kernel();
 
         return 0;
 }
@@ -1420,6 +1423,7 @@ static int lo_release(struct gendisk *disk, fmode_t mode)
         struct loop_device *lo = disk->private_data;
         int err;
 
+        lock_kernel();
         mutex_lock(&lo->lo_ctl_mutex);
 
         if (--lo->lo_refcnt)
@@ -1444,6 +1448,7 @@ static int lo_release(struct gendisk *disk, fmode_t mode)
 out:
         mutex_unlock(&lo->lo_ctl_mutex);
 out_unlocked:
+        lock_kernel();
         return 0;
 }
 
diff --git a/drivers/block/paride/pcd.c b/drivers/block/paride/pcd.c
index daba7a62a663..76f8565e1e8d 100644
--- a/drivers/block/paride/pcd.c
+++ b/drivers/block/paride/pcd.c
@@ -225,13 +225,21 @@ static char *pcd_buf;		/* buffer for request in progress */
 static int pcd_block_open(struct block_device *bdev, fmode_t mode)
 {
         struct pcd_unit *cd = bdev->bd_disk->private_data;
-        return cdrom_open(&cd->info, bdev, mode);
+        int ret;
+
+        lock_kernel();
+        ret = cdrom_open(&cd->info, bdev, mode);
+        unlock_kernel();
+
+        return ret;
 }
 
 static int pcd_block_release(struct gendisk *disk, fmode_t mode)
 {
         struct pcd_unit *cd = disk->private_data;
+        lock_kernel();
         cdrom_release(&cd->info, mode);
+        unlock_kernel();
         return 0;
 }
 
diff --git a/drivers/block/paride/pd.c b/drivers/block/paride/pd.c
index c4d6ed9846ca..985f0d4f1d1e 100644
--- a/drivers/block/paride/pd.c
+++ b/drivers/block/paride/pd.c
@@ -736,12 +736,14 @@ static int pd_open(struct block_device *bdev, fmode_t mode)
 {
         struct pd_unit *disk = bdev->bd_disk->private_data;
 
+        lock_kernel();
         disk->access++;
 
         if (disk->removable) {
                 pd_special_command(disk, pd_media_check);
                 pd_special_command(disk, pd_door_lock);
         }
+        unlock_kernel();
         return 0;
 }
 
@@ -783,8 +785,10 @@ static int pd_release(struct gendisk *p, fmode_t mode)
 {
         struct pd_unit *disk = p->private_data;
 
+        lock_kernel();
         if (!--disk->access && disk->removable)
                 pd_special_command(disk, pd_door_unlock);
+        unlock_kernel();
 
         return 0;
 }
diff --git a/drivers/block/paride/pf.c b/drivers/block/paride/pf.c
index 38b4d566b816..4457b494882a 100644
--- a/drivers/block/paride/pf.c
+++ b/drivers/block/paride/pf.c
@@ -300,20 +300,26 @@ static void __init pf_init_units(void)
 static int pf_open(struct block_device *bdev, fmode_t mode)
 {
         struct pf_unit *pf = bdev->bd_disk->private_data;
+        int ret;
 
+        lock_kernel();
         pf_identify(pf);
 
+        ret = -ENODEV;
         if (pf->media_status == PF_NM)
-                return -ENODEV;
+                goto out;
 
+        ret = -EROFS;
         if ((pf->media_status == PF_RO) && (mode & FMODE_WRITE))
-                return -EROFS;
+                goto out;
 
+        ret = 0;
         pf->access++;
         if (pf->removable)
                 pf_lock(pf, 1);
-
-        return 0;
+out:
+        unlock_kernel();
+        return ret;
 }
 
 static int pf_getgeo(struct block_device *bdev, struct hd_geometry *geo)
@@ -354,14 +360,18 @@ static int pf_release(struct gendisk *disk, fmode_t mode)
 {
         struct pf_unit *pf = disk->private_data;
 
-        if (pf->access <= 0)
+        lock_kernel();
+        if (pf->access <= 0) {
+                unlock_kernel();
                 return -EINVAL;
+        }
 
         pf->access--;
 
         if (!pf->access && pf->removable)
                 pf_lock(pf, 0);
 
+        unlock_kernel();
         return 0;
 
 }
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 40f1e31f42c4..b1cbeb59bb76 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -2383,6 +2383,7 @@ static int pkt_open(struct block_device *bdev, fmode_t mode)
 
         VPRINTK(DRIVER_NAME": entering open\n");
 
+        lock_kernel();
         mutex_lock(&ctl_mutex);
         pd = pkt_find_dev_from_minor(MINOR(bdev->bd_dev));
         if (!pd) {
@@ -2410,6 +2411,7 @@ static int pkt_open(struct block_device *bdev, fmode_t mode)
         }
 
         mutex_unlock(&ctl_mutex);
+        unlock_kernel();
         return 0;
 
 out_dec:
@@ -2417,6 +2419,7 @@ out_dec:
 out:
         VPRINTK(DRIVER_NAME": failed open (%d)\n", ret);
         mutex_unlock(&ctl_mutex);
+        unlock_kernel();
         return ret;
 }
 
@@ -2425,6 +2428,7 @@ static int pkt_close(struct gendisk *disk, fmode_t mode)
         struct pktcdvd_device *pd = disk->private_data;
         int ret = 0;
 
+        lock_kernel();
         mutex_lock(&ctl_mutex);
         pd->refcnt--;
         BUG_ON(pd->refcnt < 0);
@@ -2433,6 +2437,7 @@ static int pkt_close(struct gendisk *disk, fmode_t mode)
                 pkt_release_dev(pd, flush);
         }
         mutex_unlock(&ctl_mutex);
+        unlock_kernel();
         return ret;
 }
 
diff --git a/drivers/block/swim.c b/drivers/block/swim.c
index f04f74e3758f..2e46815876df 100644
--- a/drivers/block/swim.c
+++ b/drivers/block/swim.c
@@ -662,11 +662,23 @@ out:
         return err;
 }
 
+static int floppy_unlocked_open(struct block_device *bdev, fmode_t mode)
+{
+        int ret;
+
+        lock_kernel();
+        ret = floppy_open(bdev, mode);
+        unlock_kernel();
+
+        return ret;
+}
+
 static int floppy_release(struct gendisk *disk, fmode_t mode)
 {
         struct floppy_state *fs = disk->private_data;
         struct swim __iomem *base = fs->swd->base;
 
+        lock_kernel();
         if (fs->ref_count < 0)
                 fs->ref_count = 0;
         else if (fs->ref_count > 0)
@@ -674,6 +686,7 @@ static int floppy_release(struct gendisk *disk, fmode_t mode)
 
         if (fs->ref_count == 0)
                 swim_motor(base, OFF);
+        unlock_kernel();
 
         return 0;
 }
@@ -754,7 +767,7 @@ static int floppy_revalidate(struct gendisk *disk)
 
 static const struct block_device_operations floppy_fops = {
         .owner           = THIS_MODULE,
-        .open            = floppy_open,
+        .open            = floppy_unlocked_open,
         .release         = floppy_release,
         .ioctl           = floppy_ioctl,
         .getgeo          = floppy_getgeo,
diff --git a/drivers/block/swim3.c b/drivers/block/swim3.c
index f3657b2a5386..cc6a3864822c 100644
--- a/drivers/block/swim3.c
+++ b/drivers/block/swim3.c
@@ -949,15 +949,28 @@ static int floppy_open(struct block_device *bdev, fmode_t mode)
         return 0;
 }
 
+static int floppy_unlocked_open(struct block_device *bdev, fmode_t mode)
+{
+        int ret;
+
+        lock_kernel();
+        ret = floppy_open(bdev, mode);
+        unlock_kernel();
+
+        return ret;
+}
+
 static int floppy_release(struct gendisk *disk, fmode_t mode)
 {
         struct floppy_state *fs = disk->private_data;
         struct swim3 __iomem *sw = fs->swim3;
+        lock_kernel();
         if (fs->ref_count > 0 && --fs->ref_count == 0) {
                 swim3_action(fs, MOTOR_OFF);
                 out_8(&sw->control_bic, 0xff);
                 swim3_select(fs, RELAX);
         }
+        unlock_kernel();
         return 0;
 }
 
@@ -1008,7 +1021,7 @@ static int floppy_revalidate(struct gendisk *disk)
 }
 
 static const struct block_device_operations floppy_fops = {
-        .open           = floppy_open,
+        .open           = floppy_unlocked_open,
         .release        = floppy_release,
         .ioctl          = floppy_ioctl,
         .media_changed  = floppy_check_change,
diff --git a/drivers/block/ub.c b/drivers/block/ub.c
index 102ed52d0e0f..c48e14878582 100644
--- a/drivers/block/ub.c
+++ b/drivers/block/ub.c
@@ -1711,6 +1711,18 @@ err_open:
         return rc;
 }
 
+static int ub_bd_unlocked_open(struct block_device *bdev, fmode_t mode)
+{
+        int ret;
+
+        lock_kernel();
+        ret = ub_bd_open(bdev, mode);
+        unlock_kernel();
+
+        return ret;
+}
+
+
 /*
  */
 static int ub_bd_release(struct gendisk *disk, fmode_t mode)
@@ -1718,7 +1730,10 @@ static int ub_bd_release(struct gendisk *disk, fmode_t mode)
         struct ub_lun *lun = disk->private_data;
         struct ub_dev *sc = lun->udev;
 
+        lock_kernel();
         ub_put(sc);
+        unlock_kernel();
+
         return 0;
 }
 
@@ -1798,7 +1813,7 @@ static int ub_bd_media_changed(struct gendisk *disk)
 
 static const struct block_device_operations ub_bd_fops = {
         .owner          = THIS_MODULE,
-        .open           = ub_bd_open,
+        .open           = ub_bd_unlocked_open,
         .release        = ub_bd_release,
         .ioctl          = ub_bd_ioctl,
         .media_changed  = ub_bd_media_changed,
diff --git a/drivers/block/viodasd.c b/drivers/block/viodasd.c
index 5663d3c284c8..f651e51a3319 100644
--- a/drivers/block/viodasd.c
+++ b/drivers/block/viodasd.c
@@ -41,6 +41,7 @@
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/string.h>
+#include <linux/smp_lock.h>
 #include <linux/dma-mapping.h>
 #include <linux/completion.h>
 #include <linux/device.h>
@@ -175,6 +176,18 @@ static int viodasd_open(struct block_device *bdev, fmode_t mode)
         return 0;
 }
 
+static int viodasd_unlocked_open(struct block_device *bdev, fmode_t mode)
+{
+        int ret;
+
+        lock_kernel();
+        ret = viodasd_open(bdev, mode);
+        unlock_kernel();
+
+        return ret;
+}
+
+
 /*
  * External release entry point.
  */
@@ -183,6 +196,7 @@ static int viodasd_release(struct gendisk *disk, fmode_t mode)
         struct viodasd_device *d = disk->private_data;
         HvLpEvent_Rc hvrc;
 
+        lock_kernel();
         /* Send the event to OS/400.  We DON'T expect a response */
         hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
                         HvLpEvent_Type_VirtualIo,
@@ -195,6 +209,9 @@ static int viodasd_release(struct gendisk *disk, fmode_t mode)
                         0, 0, 0);
         if (hvrc != 0)
                 pr_warning("HV close call failed %d\n", (int)hvrc);
+
+        unlock_kernel();
+
         return 0;
 }
 
@@ -219,7 +236,7 @@ static int viodasd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
  */
 static const struct block_device_operations viodasd_fops = {
         .owner = THIS_MODULE,
-        .open = viodasd_open,
+        .open = viodasd_unlocked_open,
         .release = viodasd_release,
         .getgeo = viodasd_getgeo,
 };
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 9119cd3d56a4..91374282755d 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -41,6 +41,7 @@
 #include <linux/cdrom.h>
 #include <linux/module.h>
 #include <linux/slab.h>
+#include <linux/smp_lock.h>
 #include <linux/scatterlist.h>
 
 #include <xen/xen.h>
@@ -1018,13 +1019,18 @@ static int blkfront_is_ready(struct xenbus_device *dev)
 static int blkif_open(struct block_device *bdev, fmode_t mode)
 {
         struct blkfront_info *info = bdev->bd_disk->private_data;
+
+        lock_kernel();
         info->users++;
+        unlock_kernel();
+
         return 0;
 }
 
 static int blkif_release(struct gendisk *disk, fmode_t mode)
 {
         struct blkfront_info *info = disk->private_data;
+        lock_kernel();
         info->users--;
         if (info->users == 0) {
                 /* Check whether we have been instructed to close.  We will
@@ -1036,6 +1042,7 @@ static int blkif_release(struct gendisk *disk, fmode_t mode)
                 if (state == XenbusStateClosing && info->is_ready)
                         blkfront_closing(dev);
         }
+        unlock_kernel();
         return 0;
 }
 
diff --git a/drivers/block/xsysace.c b/drivers/block/xsysace.c
index ac278ac908d5..b71888b909a0 100644
--- a/drivers/block/xsysace.c
+++ b/drivers/block/xsysace.c
@@ -89,6 +89,7 @@
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/blkdev.h>
+#include <linux/smp_lock.h>
 #include <linux/ata.h>
 #include <linux/hdreg.h>
 #include <linux/platform_device.h>
@@ -901,11 +902,14 @@ static int ace_open(struct block_device *bdev, fmode_t mode)
 
         dev_dbg(ace->dev, "ace_open() users=%i\n", ace->users + 1);
 
+        lock_kernel();
         spin_lock_irqsave(&ace->lock, flags);
         ace->users++;
         spin_unlock_irqrestore(&ace->lock, flags);
 
         check_disk_change(bdev);
+        unlock_kernel();
+
         return 0;
 }
 
@@ -917,6 +921,7 @@ static int ace_release(struct gendisk *disk, fmode_t mode)
 
         dev_dbg(ace->dev, "ace_release() users=%i\n", ace->users - 1);
 
+        lock_kernel();
         spin_lock_irqsave(&ace->lock, flags);
         ace->users--;
         if (ace->users == 0) {
@@ -924,6 +929,7 @@ static int ace_release(struct gendisk *disk, fmode_t mode)
                 ace_out(ace, ACE_CTRL, val & ~ACE_CTRL_LOCKREQ);
         }
         spin_unlock_irqrestore(&ace->lock, flags);
+        unlock_kernel();
         return 0;
 }
 
diff --git a/drivers/block/z2ram.c b/drivers/block/z2ram.c
index 9114654b54d9..d75b2bb601ad 100644
--- a/drivers/block/z2ram.c
+++ b/drivers/block/z2ram.c
@@ -33,6 +33,7 @@
 #include <linux/module.h>
 #include <linux/blkdev.h>
 #include <linux/bitops.h>
+#include <linux/smp_lock.h>
 #include <linux/slab.h>
 
 #include <asm/setup.h>
@@ -153,6 +154,7 @@ static int z2_open(struct block_device *bdev, fmode_t mode)
 
     device = MINOR(bdev->bd_dev);
 
+    lock_kernel();
     if ( current_device != -1 && current_device != device )
     {
         rc = -EBUSY;
@@ -294,20 +296,25 @@ static int z2_open(struct block_device *bdev, fmode_t mode)
         set_capacity(z2ram_gendisk, z2ram_size >> 9);
     }
 
+    unlock_kernel();
     return 0;
 
 err_out_kfree:
     kfree(z2ram_map);
 err_out:
+    unlock_kernel();
     return rc;
 }
 
 static int
 z2_release(struct gendisk *disk, fmode_t mode)
 {
-    if ( current_device == -1 )
-        return 0;     
-
+    lock_kernel();
+    if ( current_device == -1 ) {
+        unlock_kernel();
+        return 0;
+    }
+    unlock_kernel();
     /*
      * FIXME: unmap memory
      */