Merge branch 'for-3.4/drivers' of git://git.kernel.dk/linux-block

Pull block driver bits from Jens Axboe:

 - A series of fixes for mtip32xx.  Most from Asai at Micron, but also
   one from Greg, getting rid of the dependency on PCIE_HOTPLUG.

 - A few bug fixes for xen-blkfront, and blkback.

 - A virtio-blk fix for Vivek, making resize actually work.

 - Two fixes from Stephen, making larger transfers possible on cciss.
   This is needed for tape drive support.

* 'for-3.4/drivers' of git://git.kernel.dk/linux-block:
  block: mtip32xx: remove HOTPLUG_PCI_PCIE dependancy
  mtip32xx: dump tagmap on failure
  mtip32xx: fix handling of commands in various scenarios
  mtip32xx: Shorten macro names
  mtip32xx: misc changes
  mtip32xx: Add new sysfs entry 'status'
  mtip32xx: make setting comp_time as common
  mtip32xx: Add new bitwise flag 'dd_flag'
  mtip32xx: fix error handling in mtip_init()
  virtio-blk: Call revalidate_disk() upon online disk resize
  xen/blkback: Make optional features be really optional.
  xen/blkback: Squash the discard support for 'file' and 'phy' type.
  mtip32xx: fix incorrect value set for drv_cleanup_done, and re-initialize and start port in mtip_restart_port()
  cciss: Fix scsi tape io with more than 255 scatter gather elements
  cciss: Initialize scsi host max_sectors for tape drive support
  xen-blkfront: make blkif_io_lock spinlock per-device
  xen/blkfront: don't put bdev right after getting it
  xen-blkfront: use bitmap_set() and bitmap_clear()
  xen/blkback: Enable blkback on HVM guests
  xen/blkback: use grant-table.c hypercall wrappers

Documentation/ABI/testing/sysfs-block-rssd

+What:           /sys/block/rssd*/registers
+Date:           March 2012
+KernelVersion:  3.3
+Contact:        Asai Thambi S P <asamymuthupa@micron.com>
+Description:    This is a read-only file. Dumps below driver information and
+                hardware registers.
+                    - S ACTive
+                    - Command Issue
+                    - Allocated
+                    - Completed
+                    - PORT IRQ STAT
+                    - HOST IRQ STAT
+
+What:           /sys/block/rssd*/status
+Date:           April 2012
+KernelVersion:  3.4
+Contact:        Asai Thambi S P <asamymuthupa@micron.com>
+Description:   This is a read-only file. Indicates the status of the device.

drivers/block/cciss_scsi.c

@@ -866,6 +866,7 @@ cciss_scsi_detect(ctlr_info_t *h)
 	sh->can_queue = cciss_tape_cmds;
 	sh->sg_tablesize = h->maxsgentries;
 	sh->max_cmd_len = MAX_COMMAND_SIZE;
+	sh->max_sectors = h->cciss_max_sectors;
 
 	((struct cciss_scsi_adapter_data_t *) 
 		h->scsi_ctlr)->scsi_host = sh;
@@ -1410,7 +1411,7 @@ static void cciss_scatter_gather(ctlr_info_t *h, CommandList_struct *c,
 	/* track how many SG entries we are using */
 	if (request_nsgs > h->maxSG)
 		h->maxSG = request_nsgs;
-	c->Header.SGTotal = (__u8) request_nsgs + chained;
+	c->Header.SGTotal = (u16) request_nsgs + chained;
 	if (request_nsgs > h->max_cmd_sgentries)
 		c->Header.SGList = h->max_cmd_sgentries;
 	else

drivers/block/mtip32xx/Kconfig

@@ -4,6 +4,6 @@
 
 config BLK_DEV_PCIESSD_MTIP32XX
 	tristate "Block Device Driver for Micron PCIe SSDs"
-	depends on HOTPLUG_PCI_PCIE
+	depends on PCI
 	help
           This enables the block driver for Micron PCIe SSDs.

drivers/block/mtip32xx/mtip32xx.h

@@ -34,8 +34,8 @@
 /* offset of Device Control register in PCIe extended capabilites space */
 #define PCIE_CONFIG_EXT_DEVICE_CONTROL_OFFSET	0x48
 
-/* # of times to retry timed out IOs */
-#define MTIP_MAX_RETRIES	5
+/* # of times to retry timed out/failed IOs */
+#define MTIP_MAX_RETRIES	2
 
 /* Various timeout values in ms */
 #define MTIP_NCQ_COMMAND_TIMEOUT_MS       5000
@@ -114,12 +114,41 @@
 #define __force_bit2int (unsigned int __force)
 
 /* below are bit numbers in 'flags' defined in mtip_port */
-#define MTIP_FLAG_IC_ACTIVE_BIT			0
-#define MTIP_FLAG_EH_ACTIVE_BIT			1
-#define MTIP_FLAG_SVC_THD_ACTIVE_BIT		2
-#define MTIP_FLAG_ISSUE_CMDS_BIT		4
-#define MTIP_FLAG_REBUILD_BIT			5
-#define MTIP_FLAG_SVC_THD_SHOULD_STOP_BIT	8
+#define MTIP_PF_IC_ACTIVE_BIT		0 /* pio/ioctl */
+#define MTIP_PF_EH_ACTIVE_BIT		1 /* error handling */
+#define MTIP_PF_SE_ACTIVE_BIT		2 /* secure erase */
+#define MTIP_PF_DM_ACTIVE_BIT		3 /* download microcde */
+#define MTIP_PF_PAUSE_IO	((1 << MTIP_PF_IC_ACTIVE_BIT) | \
+				(1 << MTIP_PF_EH_ACTIVE_BIT) | \
+				(1 << MTIP_PF_SE_ACTIVE_BIT) | \
+				(1 << MTIP_PF_DM_ACTIVE_BIT))
+
+#define MTIP_PF_SVC_THD_ACTIVE_BIT	4
+#define MTIP_PF_ISSUE_CMDS_BIT		5
+#define MTIP_PF_REBUILD_BIT		6
+#define MTIP_PF_SVC_THD_STOP_BIT	8
+
+/* below are bit numbers in 'dd_flag' defined in driver_data */
+#define MTIP_DDF_REMOVE_PENDING_BIT	1
+#define MTIP_DDF_OVER_TEMP_BIT		2
+#define MTIP_DDF_WRITE_PROTECT_BIT	3
+#define MTIP_DDF_STOP_IO	((1 << MTIP_DDF_REMOVE_PENDING_BIT) | \
+				(1 << MTIP_DDF_OVER_TEMP_BIT) | \
+				(1 << MTIP_DDF_WRITE_PROTECT_BIT))
+
+#define MTIP_DDF_CLEANUP_BIT		5
+#define MTIP_DDF_RESUME_BIT		6
+#define MTIP_DDF_INIT_DONE_BIT		7
+#define MTIP_DDF_REBUILD_FAILED_BIT	8
+
+__packed struct smart_attr{
+	u8 attr_id;
+	u16 flags;
+	u8 cur;
+	u8 worst;
+	u32 data;
+	u8 res[3];
+};
 
 /* Register Frame Information Structure (FIS), host to device. */
 struct host_to_dev_fis {
@@ -345,6 +374,12 @@ struct mtip_port {
 	 * when the command slot and all associated data structures
 	 * are no longer needed.
 	 */
+	u16 *log_buf;
+	dma_addr_t log_buf_dma;
+
+	u8 *smart_buf;
+	dma_addr_t smart_buf_dma;
+
 	unsigned long allocated[SLOTBITS_IN_LONGS];
 	/*
 	 * used to queue commands when an internal command is in progress
@@ -368,6 +403,7 @@ struct mtip_port {
 	 * Timer used to complete commands that have been active for too long.
 	 */
 	struct timer_list cmd_timer;
+	unsigned long ic_pause_timer;
 	/*
 	 * Semaphore used to block threads if there are no
 	 * command slots available.
@@ -404,13 +440,9 @@ struct driver_data {
 
 	unsigned slot_groups; /* number of slot groups the product supports */
 
-	atomic_t drv_cleanup_done; /* Atomic variable for SRSI */
-
 	unsigned long index; /* Index to determine the disk name */
 
-	unsigned int ftlrebuildflag; /* FTL rebuild flag */
-
-	atomic_t resumeflag; /* Atomic variable to track suspend/resume */
+	unsigned long dd_flag; /* NOTE: use atomic bit operations on this */
 
 	struct task_struct *mtip_svc_handler; /* task_struct of svc thd */
 };

drivers/block/virtio_blk.c

@@ -351,6 +351,7 @@ static void virtblk_config_changed_work(struct work_struct *work)
 		  cap_str_10, cap_str_2);
 
 	set_capacity(vblk->disk, capacity);
+	revalidate_disk(vblk->disk);
 done:
 	mutex_unlock(&vblk->config_lock);
 }

drivers/block/xen-blkback/blkback.c

@@ -321,6 +321,7 @@ struct seg_buf {
 static void xen_blkbk_unmap(struct pending_req *req)
 {
 	struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+	struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
 	unsigned int i, invcount = 0;
 	grant_handle_t handle;
 	int ret;
@@ -332,25 +333,12 @@ static void xen_blkbk_unmap(struct pending_req *req)
 		gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i),
 				    GNTMAP_host_map, handle);
 		pending_handle(req, i) = BLKBACK_INVALID_HANDLE;
+		pages[invcount] = virt_to_page(vaddr(req, i));
 		invcount++;
 	}
 
-	ret = HYPERVISOR_grant_table_op(
-		GNTTABOP_unmap_grant_ref, unmap, invcount);
+	ret = gnttab_unmap_refs(unmap, pages, invcount, false);
 	BUG_ON(ret);
-	/*
-	 * Note, we use invcount, so nr->pages, so we can't index
-	 * using vaddr(req, i).
-	 */
-	for (i = 0; i < invcount; i++) {
-		ret = m2p_remove_override(
-			virt_to_page(unmap[i].host_addr), false);
-		if (ret) {
-			pr_alert(DRV_PFX "Failed to remove M2P override for %lx\n",
-				 (unsigned long)unmap[i].host_addr);
-			continue;
-		}
-	}
 }
 
 static int xen_blkbk_map(struct blkif_request *req,
@@ -378,7 +366,7 @@ static int xen_blkbk_map(struct blkif_request *req,
 				  pending_req->blkif->domid);
 	}
 
-	ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map, nseg);
+	ret = gnttab_map_refs(map, NULL, &blkbk->pending_page(pending_req, 0), nseg);
 	BUG_ON(ret);
 
 	/*
@@ -398,15 +386,6 @@ static int xen_blkbk_map(struct blkif_request *req,
 		if (ret)
 			continue;
 
-		ret = m2p_add_override(PFN_DOWN(map[i].dev_bus_addr),
-			blkbk->pending_page(pending_req, i), NULL);
-		if (ret) {
-			pr_alert(DRV_PFX "Failed to install M2P override for %lx (ret: %d)\n",
-				 (unsigned long)map[i].dev_bus_addr, ret);
-			/* We could switch over to GNTTABOP_copy */
-			continue;
-		}
-
 		seg[i].buf  = map[i].dev_bus_addr |
 			(req->u.rw.seg[i].first_sect << 9);
 	}
@@ -419,21 +398,18 @@ static int dispatch_discard_io(struct xen_blkif *blkif,
 	int err = 0;
 	int status = BLKIF_RSP_OKAY;
 	struct block_device *bdev = blkif->vbd.bdev;
+	unsigned long secure;
 
 	blkif->st_ds_req++;
 
 	xen_blkif_get(blkif);
-	if (blkif->blk_backend_type == BLKIF_BACKEND_PHY ||
-	    blkif->blk_backend_type == BLKIF_BACKEND_FILE) {
-		unsigned long secure = (blkif->vbd.discard_secure &&
+	secure = (blkif->vbd.discard_secure &&
 		 (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ?
 		 BLKDEV_DISCARD_SECURE : 0;
-		err = blkdev_issue_discard(bdev,
-				req->u.discard.sector_number,
+
+	err = blkdev_issue_discard(bdev, req->u.discard.sector_number,
 				   req->u.discard.nr_sectors,
 				   GFP_KERNEL, secure);
-	} else
-		err = -EOPNOTSUPP;
 
 	if (err == -EOPNOTSUPP) {
 		pr_debug(DRV_PFX "discard op failed, not supported\n");
@@ -830,7 +806,7 @@ static int __init xen_blkif_init(void)
 	int i, mmap_pages;
 	int rc = 0;
 
-	if (!xen_pv_domain())
+	if (!xen_domain())
 		return -ENODEV;
 
 	blkbk = kzalloc(sizeof(struct xen_blkbk), GFP_KERNEL);

drivers/block/xen-blkback/common.h

@@ -146,11 +146,6 @@ enum blkif_protocol {
 	BLKIF_PROTOCOL_X86_64 = 3,
 };
 
-enum blkif_backend_type {
-	BLKIF_BACKEND_PHY  = 1,
-	BLKIF_BACKEND_FILE = 2,
-};
-
 struct xen_vbd {
 	/* What the domain refers to this vbd as. */
 	blkif_vdev_t		handle;
@@ -177,7 +172,6 @@ struct xen_blkif {
 	unsigned int		irq;
 	/* Comms information. */
 	enum blkif_protocol	blk_protocol;
-	enum blkif_backend_type blk_backend_type;
 	union blkif_back_rings	blk_rings;
 	void			*blk_ring;
 	/* The VBD attached to this interface. */

drivers/block/xen-blkback/xenbus.c

@@ -381,72 +381,49 @@ int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
 	err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache",
 			    "%d", state);
 	if (err)
-		xenbus_dev_fatal(dev, err, "writing feature-flush-cache");
+		dev_warn(&dev->dev, "writing feature-flush-cache (%d)", err);
 
 	return err;
 }
 
-int xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be)
+static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be)
 {
 	struct xenbus_device *dev = be->dev;
 	struct xen_blkif *blkif = be->blkif;
-	char *type;
 	int err;
 	int state = 0;
-
-	type = xenbus_read(XBT_NIL, dev->nodename, "type", NULL);
-	if (!IS_ERR(type)) {
-		if (strncmp(type, "file", 4) == 0) {
-			state = 1;
-			blkif->blk_backend_type = BLKIF_BACKEND_FILE;
-		}
-		if (strncmp(type, "phy", 3) == 0) {
 	struct block_device *bdev = be->blkif->vbd.bdev;
 	struct request_queue *q = bdev_get_queue(bdev);
+
 	if (blk_queue_discard(q)) {
 		err = xenbus_printf(xbt, dev->nodename,
 			"discard-granularity", "%u",
 			q->limits.discard_granularity);
 		if (err) {
-					xenbus_dev_fatal(dev, err,
-						"writing discard-granularity");
-					goto kfree;
+			dev_warn(&dev->dev, "writing discard-granularity (%d)", err);
+			return;
 		}
 		err = xenbus_printf(xbt, dev->nodename,
 			"discard-alignment", "%u",
 			q->limits.discard_alignment);
 		if (err) {
-					xenbus_dev_fatal(dev, err,
-						"writing discard-alignment");
-					goto kfree;
+			dev_warn(&dev->dev, "writing discard-alignment (%d)", err);
+			return;
 		}
 		state = 1;
-				blkif->blk_backend_type = BLKIF_BACKEND_PHY;
-			}
 		/* Optional. */
 		err = xenbus_printf(xbt, dev->nodename,
 				    "discard-secure", "%d",
 				    blkif->vbd.discard_secure);
 		if (err) {
-				xenbus_dev_fatal(dev, err,
-					"writting discard-secure");
-				goto kfree;
-			}
+			dev_warn(dev-dev, "writing discard-secure (%d)", err);
+			return;
 		}
-	} else {
-		err = PTR_ERR(type);
-		xenbus_dev_fatal(dev, err, "reading type");
-		goto out;
 	}
-
 	err = xenbus_printf(xbt, dev->nodename, "feature-discard",
 			    "%d", state);
 	if (err)
-		xenbus_dev_fatal(dev, err, "writing feature-discard");
-kfree:
-	kfree(type);
-out:
-	return err;
+		dev_warn(&dev->dev, "writing feature-discard (%d)", err);
 }
 int xen_blkbk_barrier(struct xenbus_transaction xbt,
 		      struct backend_info *be, int state)
@@ -457,7 +434,7 @@ int xen_blkbk_barrier(struct xenbus_transaction xbt,
 	err = xenbus_printf(xbt, dev->nodename, "feature-barrier",
 			    "%d", state);
 	if (err)
-		xenbus_dev_fatal(dev, err, "writing feature-barrier");
+		dev_warn(&dev->dev, "writing feature-barrier (%d)", err);
 
 	return err;
 }
@@ -689,14 +666,12 @@ static void connect(struct backend_info *be)
 		return;
 	}
 
-	err = xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support);
-	if (err)
-		goto abort;
+	/* If we can't advertise it is OK. */
+	xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support);
 
-	err = xen_blkbk_discard(xbt, be);
+	xen_blkbk_discard(xbt, be);
 
-	/* If we can't advertise it is OK. */
-	err = xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support);
+	xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support);
 
 	err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
 			    (unsigned long long)vbd_sz(&be->blkif->vbd));

drivers/block/xen-blkfront.c

@@ -43,6 +43,7 @@
 #include <linux/slab.h>
 #include <linux/mutex.h>
 #include <linux/scatterlist.h>
+#include <linux/bitmap.h>
 
 #include <xen/xen.h>
 #include <xen/xenbus.h>
@@ -81,6 +82,7 @@ static const struct block_device_operations xlvbd_block_fops;
  */
 struct blkfront_info
 {
+	spinlock_t io_lock;
 	struct mutex mutex;
 	struct xenbus_device *xbdev;
 	struct gendisk *gd;
@@ -105,8 +107,6 @@ struct blkfront_info
 	int is_ready;
 };
 
-static DEFINE_SPINLOCK(blkif_io_lock);
-
 static unsigned int nr_minors;
 static unsigned long *minors;
 static DEFINE_SPINLOCK(minor_lock);
@@ -177,8 +177,7 @@ static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
 
 	spin_lock(&minor_lock);
 	if (find_next_bit(minors, end, minor) >= end) {
-		for (; minor < end; ++minor)
-			__set_bit(minor, minors);
+		bitmap_set(minors, minor, nr);
 		rc = 0;
 	} else
 		rc = -EBUSY;
@@ -193,8 +192,7 @@ static void xlbd_release_minors(unsigned int minor, unsigned int nr)
 
 	BUG_ON(end > nr_minors);
 	spin_lock(&minor_lock);
-	for (; minor < end; ++minor)
-		__clear_bit(minor, minors);
+	bitmap_clear(minors,  minor, nr);
 	spin_unlock(&minor_lock);
 }
 
@@ -419,7 +417,7 @@ static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
 	struct request_queue *rq;
 	struct blkfront_info *info = gd->private_data;
 
-	rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
+	rq = blk_init_queue(do_blkif_request, &info->io_lock);
 	if (rq == NULL)
 		return -1;
 
@@ -636,14 +634,14 @@ static void xlvbd_release_gendisk(struct blkfront_info *info)
 	if (info->rq == NULL)
 		return;
 
-	spin_lock_irqsave(&blkif_io_lock, flags);
+	spin_lock_irqsave(&info->io_lock, flags);
 
 	/* No more blkif_request(). */
 	blk_stop_queue(info->rq);
 
 	/* No more gnttab callback work. */
 	gnttab_cancel_free_callback(&info->callback);
-	spin_unlock_irqrestore(&blkif_io_lock, flags);
+	spin_unlock_irqrestore(&info->io_lock, flags);
 
 	/* Flush gnttab callback work. Must be done with no locks held. */
 	flush_work_sync(&info->work);
@@ -675,16 +673,16 @@ static void blkif_restart_queue(struct work_struct *work)
 {
 	struct blkfront_info *info = container_of(work, struct blkfront_info, work);
 
-	spin_lock_irq(&blkif_io_lock);
+	spin_lock_irq(&info->io_lock);
 	if (info->connected == BLKIF_STATE_CONNECTED)
 		kick_pending_request_queues(info);
-	spin_unlock_irq(&blkif_io_lock);
+	spin_unlock_irq(&info->io_lock);
 }
 
 static void blkif_free(struct blkfront_info *info, int suspend)
 {
 	/* Prevent new requests being issued until we fix things up. */
-	spin_lock_irq(&blkif_io_lock);
+	spin_lock_irq(&info->io_lock);
 	info->connected = suspend ?
 		BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
 	/* No more blkif_request(). */
@@ -692,7 +690,7 @@ static void blkif_free(struct blkfront_info *info, int suspend)
 		blk_stop_queue(info->rq);
 	/* No more gnttab callback work. */
 	gnttab_cancel_free_callback(&info->callback);
-	spin_unlock_irq(&blkif_io_lock);
+	spin_unlock_irq(&info->io_lock);
 
 	/* Flush gnttab callback work. Must be done with no locks held. */
 	flush_work_sync(&info->work);
@@ -728,10 +726,10 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 	struct blkfront_info *info = (struct blkfront_info *)dev_id;
 	int error;
 
-	spin_lock_irqsave(&blkif_io_lock, flags);
+	spin_lock_irqsave(&info->io_lock, flags);
 
 	if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
-		spin_unlock_irqrestore(&blkif_io_lock, flags);
+		spin_unlock_irqrestore(&info->io_lock, flags);
 		return IRQ_HANDLED;
 	}
 
@@ -816,7 +814,7 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 
 	kick_pending_request_queues(info);
 
-	spin_unlock_irqrestore(&blkif_io_lock, flags);
+	spin_unlock_irqrestore(&info->io_lock, flags);
 
 	return IRQ_HANDLED;
 }
@@ -991,6 +989,7 @@ static int blkfront_probe(struct xenbus_device *dev,
 	}
 
 	mutex_init(&info->mutex);
+	spin_lock_init(&info->io_lock);
 	info->xbdev = dev;
 	info->vdevice = vdevice;
 	info->connected = BLKIF_STATE_DISCONNECTED;
@@ -1068,7 +1067,7 @@ static int blkif_recover(struct blkfront_info *info)
 
 	xenbus_switch_state(info->xbdev, XenbusStateConnected);
 
-	spin_lock_irq(&blkif_io_lock);
+	spin_lock_irq(&info->io_lock);
 
 	/* Now safe for us to use the shared ring */
 	info->connected = BLKIF_STATE_CONNECTED;
@@ -1079,7 +1078,7 @@ static int blkif_recover(struct blkfront_info *info)
 	/* Kick any other new requests queued since we resumed */
 	kick_pending_request_queues(info);
 
-	spin_unlock_irq(&blkif_io_lock);
+	spin_unlock_irq(&info->io_lock);
 
 	return 0;
 }
@@ -1277,10 +1276,10 @@ static void blkfront_connect(struct blkfront_info *info)
 	xenbus_switch_state(info->xbdev, XenbusStateConnected);
 
 	/* Kick pending requests. */
-	spin_lock_irq(&blkif_io_lock);
+	spin_lock_irq(&info->io_lock);
 	info->connected = BLKIF_STATE_CONNECTED;
 	kick_pending_request_queues(info);
-	spin_unlock_irq(&blkif_io_lock);
+	spin_unlock_irq(&info->io_lock);
 
 	add_disk(info->gd);
 
@@ -1410,7 +1409,6 @@ static int blkif_release(struct gendisk *disk, fmode_t mode)
 	mutex_lock(&blkfront_mutex);
 
 	bdev = bdget_disk(disk, 0);
-	bdput(bdev);
 
 	if (bdev->bd_openers)
 		goto out;
@@ -1441,6 +1439,7 @@ static int blkif_release(struct gendisk *disk, fmode_t mode)
 	}
 
 out:
+	bdput(bdev);
 	mutex_unlock(&blkfront_mutex);
 	return 0;
 }