xen/blkback: Squash vbd.c,interface.c in blkback.c and xenbus.c respectivly.

Daniel Stodden suggested to eliminate vbd.c and interface.c, inlining the
critical bits where they belong, respectively.

Leaving only blkback.c for the data- and xenbus.c for the control path.

Suggested-by:  Daniel Stodden <daniel.stodden@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

5 files changed, 287 insertions, 348 deletions

diff --git a/drivers/block/xen-blkback/Makefile b/drivers/block/xen-blkback/Makefile
index f1ae1ff07a4d..e491c1b76878 100644
--- a/drivers/block/xen-blkback/Makefile
+++ b/drivers/block/xen-blkback/Makefile
@@ -1,3 +1,3 @@
 obj-$(CONFIG_XEN_BLKDEV_BACKEND) := xen-blkback.o
 
-xen-blkback-y	:= blkback.o xenbus.o interface.o vbd.o
+xen-blkback-y	:= blkback.o xenbus.o
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 59a2bae0f35e..63001fac9af2 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -167,6 +167,141 @@ static void free_req(struct pending_req *req)
 }
 
 /*
+ * Routines for managing virtual block devices (vbds).
+ */
+
+#define vbd_sz(_v)	((_v)->bdev->bd_part ? \
+			 (_v)->bdev->bd_part->nr_sects : \
+			  get_capacity((_v)->bdev->bd_disk))
+
+unsigned long long vbd_size(struct vbd *vbd)
+{
+	return vbd_sz(vbd);
+}
+
+unsigned int vbd_info(struct vbd *vbd)
+{
+	return vbd->type | (vbd->readonly ? VDISK_READONLY : 0);
+}
+
+unsigned long vbd_secsize(struct vbd *vbd)
+{
+	return bdev_logical_block_size(vbd->bdev);
+}
+
+int vbd_create(struct blkif_st *blkif, blkif_vdev_t handle, unsigned major,
+	       unsigned minor, int readonly, int cdrom)
+{
+	struct vbd *vbd;
+	struct block_device *bdev;
+
+	vbd = &blkif->vbd;
+	vbd->handle   = handle;
+	vbd->readonly = readonly;
+	vbd->type     = 0;
+
+	vbd->pdevice  = MKDEV(major, minor);
+
+	bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ?
+				 FMODE_READ : FMODE_WRITE, NULL);
+
+	if (IS_ERR(bdev)) {
+		DPRINTK("vbd_creat: device %08x could not be opened.\n",
+			vbd->pdevice);
+		return -ENOENT;
+	}
+
+	vbd->bdev = bdev;
+	vbd->size = vbd_size(vbd);
+
+	if (vbd->bdev->bd_disk == NULL) {
+		DPRINTK("vbd_creat: device %08x doesn't exist.\n",
+			vbd->pdevice);
+		vbd_free(vbd);
+		return -ENOENT;
+	}
+
+	if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom)
+		vbd->type |= VDISK_CDROM;
+	if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE)
+		vbd->type |= VDISK_REMOVABLE;
+
+	DPRINTK("Successful creation of handle=%04x (dom=%u)\n",
+		handle, blkif->domid);
+	return 0;
+}
+
+void vbd_free(struct vbd *vbd)
+{
+	if (vbd->bdev)
+		blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE);
+	vbd->bdev = NULL;
+}
+
+int vbd_translate(struct phys_req *req, struct blkif_st *blkif, int operation)
+{
+	struct vbd *vbd = &blkif->vbd;
+	int rc = -EACCES;
+
+	if ((operation != READ) && vbd->readonly)
+		goto out;
+
+	if (unlikely((req->sector_number + req->nr_sects) > vbd_sz(vbd)))
+		goto out;
+
+	req->dev  = vbd->pdevice;
+	req->bdev = vbd->bdev;
+	rc = 0;
+
+ out:
+	return rc;
+}
+
+void vbd_resize(struct blkif_st *blkif)
+{
+	struct vbd *vbd = &blkif->vbd;
+	struct xenbus_transaction xbt;
+	int err;
+	struct xenbus_device *dev = blkback_xenbus(blkif->be);
+	unsigned long long new_size = vbd_size(vbd);
+
+	printk(KERN_INFO "VBD Resize: Domid: %d, Device: (%d, %d)\n",
+		blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice));
+	printk(KERN_INFO "VBD Resize: new size %llu\n", new_size);
+	vbd->size = new_size;
+again:
+	err = xenbus_transaction_start(&xbt);
+	if (err) {
+		printk(KERN_WARNING "Error starting transaction");
+		return;
+	}
+	err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
+			    vbd_size(vbd));
+	if (err) {
+		printk(KERN_WARNING "Error writing new size");
+		goto abort;
+	}
+	/*
+	 * Write the current state; we will use this to synchronize
+	 * the front-end. If the current state is "connected" the
+	 * front-end will get the new size information online.
+	 */
+	err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state);
+	if (err) {
+		printk(KERN_WARNING "Error writing the state");
+		goto abort;
+	}
+
+	err = xenbus_transaction_end(xbt, 0);
+	if (err == -EAGAIN)
+		goto again;
+	if (err)
+		printk(KERN_WARNING "Error ending transaction");
+abort:
+	xenbus_transaction_end(xbt, 1);
+}
+
+/*
  * Notification from the guest OS.
  */
 static void blkif_notify_work(struct blkif_st *blkif)
diff --git a/drivers/block/xen-blkback/interface.c b/drivers/block/xen-blkback/interface.c
deleted file mode 100644
index 163aed41e825..000000000000
--- a/drivers/block/xen-blkback/interface.c
+++ /dev/null
@@ -1,185 +0,0 @@
-/******************************************************************************
- * Block-device interface management.
- *
- * Copyright (c) 2004, Keir Fraser
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License version 2
- * as published by the Free Software Foundation; or, when distributed
- * separately from the Linux kernel or incorporated into other
- * software packages, subject to the following license:
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this source file (the "Software"), to deal in the Software without
- * restriction, including without limitation the rights to use, copy, modify,
- * merge, publish, distribute, sublicense, and/or sell copies of the Software,
- * and to permit persons to whom the Software is furnished to do so, subject to
- * the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
- * IN THE SOFTWARE.
- */
-
-#include "common.h"
-#include <xen/events.h>
-#include <xen/grant_table.h>
-#include <linux/kthread.h>
-
-static struct kmem_cache *blkif_cachep;
-
-struct blkif_st *blkif_alloc(domid_t domid)
-{
-	struct blkif_st *blkif;
-
-	blkif = kmem_cache_alloc(blkif_cachep, GFP_KERNEL);
-	if (!blkif)
-		return ERR_PTR(-ENOMEM);
-
-	memset(blkif, 0, sizeof(*blkif));
-	blkif->domid = domid;
-	spin_lock_init(&blkif->blk_ring_lock);
-	atomic_set(&blkif->refcnt, 1);
-	init_waitqueue_head(&blkif->wq);
-	blkif->st_print = jiffies;
-	init_waitqueue_head(&blkif->waiting_to_free);
-
-	return blkif;
-}
-
-static int map_frontend_page(struct blkif_st *blkif, unsigned long shared_page)
-{
-	struct gnttab_map_grant_ref op;
-
-	gnttab_set_map_op(&op, (unsigned long)blkif->blk_ring_area->addr,
-			  GNTMAP_host_map, shared_page, blkif->domid);
-
-	if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
-		BUG();
-
-	if (op.status) {
-		DPRINTK(" Grant table operation failure !\n");
-		return op.status;
-	}
-
-	blkif->shmem_ref = shared_page;
-	blkif->shmem_handle = op.handle;
-
-	return 0;
-}
-
-static void unmap_frontend_page(struct blkif_st *blkif)
-{
-	struct gnttab_unmap_grant_ref op;
-
-	gnttab_set_unmap_op(&op, (unsigned long)blkif->blk_ring_area->addr,
-			    GNTMAP_host_map, blkif->shmem_handle);
-
-	if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
-		BUG();
-}
-
-int blkif_map(struct blkif_st *blkif, unsigned long shared_page,
-	      unsigned int evtchn)
-{
-	int err;
-
-	/* Already connected through? */
-	if (blkif->irq)
-		return 0;
-
-	blkif->blk_ring_area = alloc_vm_area(PAGE_SIZE);
-	if (!blkif->blk_ring_area)
-		return -ENOMEM;
-
-	err = map_frontend_page(blkif, shared_page);
-	if (err) {
-		free_vm_area(blkif->blk_ring_area);
-		return err;
-	}
-
-	switch (blkif->blk_protocol) {
-	case BLKIF_PROTOCOL_NATIVE:
-	{
-		struct blkif_sring *sring;
-		sring = (struct blkif_sring *)blkif->blk_ring_area->addr;
-		BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE);
-		break;
-	}
-	case BLKIF_PROTOCOL_X86_32:
-	{
-		struct blkif_x86_32_sring *sring_x86_32;
-		sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring_area->addr;
-		BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE);
-		break;
-	}
-	case BLKIF_PROTOCOL_X86_64:
-	{
-		struct blkif_x86_64_sring *sring_x86_64;
-		sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring_area->addr;
-		BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE);
-		break;
-	}
-	default:
-		BUG();
-	}
-
-	err = bind_interdomain_evtchn_to_irqhandler(
-		blkif->domid, evtchn, blkif_be_int, 0, "blkif-backend", blkif);
-	if (err < 0) {
-		unmap_frontend_page(blkif);
-		free_vm_area(blkif->blk_ring_area);
-		blkif->blk_rings.common.sring = NULL;
-		return err;
-	}
-	blkif->irq = err;
-
-	return 0;
-}
-
-void blkif_disconnect(struct blkif_st *blkif)
-{
-	if (blkif->xenblkd) {
-		kthread_stop(blkif->xenblkd);
-		blkif->xenblkd = NULL;
-	}
-
-	atomic_dec(&blkif->refcnt);
-	wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0);
-	atomic_inc(&blkif->refcnt);
-
-	if (blkif->irq) {
-		unbind_from_irqhandler(blkif->irq, blkif);
-		blkif->irq = 0;
-	}
-
-	if (blkif->blk_rings.common.sring) {
-		unmap_frontend_page(blkif);
-		free_vm_area(blkif->blk_ring_area);
-		blkif->blk_rings.common.sring = NULL;
-	}
-}
-
-void blkif_free(struct blkif_st *blkif)
-{
-	if (!atomic_dec_and_test(&blkif->refcnt))
-		BUG();
-	kmem_cache_free(blkif_cachep, blkif);
-}
-
-int __init blkif_interface_init(void)
-{
-	blkif_cachep = kmem_cache_create("blkif_cache", sizeof(struct blkif_st),
-					 0, 0, NULL);
-	if (!blkif_cachep)
-		return -ENOMEM;
-
-	return 0;
-}
diff --git a/drivers/block/xen-blkback/vbd.c b/drivers/block/xen-blkback/vbd.c
deleted file mode 100644
index d0ff4cf91a34..000000000000
--- a/drivers/block/xen-blkback/vbd.c
+++ /dev/null
@@ -1,162 +0,0 @@
-/******************************************************************************
- * Routines for managing virtual block devices (VBDs).
- *
- * Copyright (c) 2003-2005, Keir Fraser & Steve Hand
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License version 2
- * as published by the Free Software Foundation; or, when distributed
- * separately from the Linux kernel or incorporated into other
- * software packages, subject to the following license:
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this source file (the "Software"), to deal in the Software without
- * restriction, including without limitation the rights to use, copy, modify,
- * merge, publish, distribute, sublicense, and/or sell copies of the Software,
- * and to permit persons to whom the Software is furnished to do so, subject to
- * the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
- * IN THE SOFTWARE.
- */
-
-#include "common.h"
-
-#define vbd_sz(_v)	((_v)->bdev->bd_part ? \
-			 (_v)->bdev->bd_part->nr_sects : \
-			  get_capacity((_v)->bdev->bd_disk))
-
-unsigned long long vbd_size(struct vbd *vbd)
-{
-	return vbd_sz(vbd);
-}
-
-unsigned int vbd_info(struct vbd *vbd)
-{
-	return vbd->type | (vbd->readonly ? VDISK_READONLY : 0);
-}
-
-unsigned long vbd_secsize(struct vbd *vbd)
-{
-	return bdev_logical_block_size(vbd->bdev);
-}
-
-int vbd_create(struct blkif_st *blkif, blkif_vdev_t handle, unsigned major,
-	       unsigned minor, int readonly, int cdrom)
-{
-	struct vbd *vbd;
-	struct block_device *bdev;
-
-	vbd = &blkif->vbd;
-	vbd->handle   = handle;
-	vbd->readonly = readonly;
-	vbd->type     = 0;
-
-	vbd->pdevice  = MKDEV(major, minor);
-
-	bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ?
-				 FMODE_READ : FMODE_WRITE, NULL);
-
-	if (IS_ERR(bdev)) {
-		DPRINTK("vbd_creat: device %08x could not be opened.\n",
-			vbd->pdevice);
-		return -ENOENT;
-	}
-
-	vbd->bdev = bdev;
-	vbd->size = vbd_size(vbd);
-
-	if (vbd->bdev->bd_disk == NULL) {
-		DPRINTK("vbd_creat: device %08x doesn't exist.\n",
-			vbd->pdevice);
-		vbd_free(vbd);
-		return -ENOENT;
-	}
-
-	if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom)
-		vbd->type |= VDISK_CDROM;
-	if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE)
-		vbd->type |= VDISK_REMOVABLE;
-
-	DPRINTK("Successful creation of handle=%04x (dom=%u)\n",
-		handle, blkif->domid);
-	return 0;
-}
-
-void vbd_free(struct vbd *vbd)
-{
-	if (vbd->bdev)
-		blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE);
-	vbd->bdev = NULL;
-}
-
-int vbd_translate(struct phys_req *req, struct blkif_st *blkif, int operation)
-{
-	struct vbd *vbd = &blkif->vbd;
-	int rc = -EACCES;
-
-	if ((operation != READ) && vbd->readonly)
-		goto out;
-
-	if (unlikely((req->sector_number + req->nr_sects) > vbd_sz(vbd)))
-		goto out;
-
-	req->dev  = vbd->pdevice;
-	req->bdev = vbd->bdev;
-	rc = 0;
-
- out:
-	return rc;
-}
-
-void vbd_resize(struct blkif_st *blkif)
-{
-	struct vbd *vbd = &blkif->vbd;
-	struct xenbus_transaction xbt;
-	int err;
-	struct xenbus_device *dev = blkback_xenbus(blkif->be);
-	unsigned long long new_size = vbd_size(vbd);
-
-	printk(KERN_INFO "VBD Resize: Domid: %d, Device: (%d, %d)\n",
-		blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice));
-	printk(KERN_INFO "VBD Resize: new size %llu\n", new_size);
-	vbd->size = new_size;
-again:
-	err = xenbus_transaction_start(&xbt);
-	if (err) {
-		printk(KERN_WARNING "Error starting transaction");
-		return;
-	}
-	err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
-			    vbd_size(vbd));
-	if (err) {
-		printk(KERN_WARNING "Error writing new size");
-		goto abort;
-	}
-	/*
-	 * Write the current state; we will use this to synchronize
-	 * the front-end. If the current state is "connected" the
-	 * front-end will get the new size information online.
-	 */
-	err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state);
-	if (err) {
-		printk(KERN_WARNING "Error writing the state");
-		goto abort;
-	}
-
-	err = xenbus_transaction_end(xbt, 0);
-	if (err == -EAGAIN)
-		goto again;
-	if (err)
-		printk(KERN_WARNING "Error ending transaction");
-abort:
-	xenbus_transaction_end(xbt, 1);
-}
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index b41ed65db2d3..0c263a248007 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -20,6 +20,8 @@
 #include <stdarg.h>
 #include <linux/module.h>
 #include <linux/kthread.h>
+#include <xen/events.h>
+#include <xen/grant_table.h>
 #include "common.h"
 
 #undef DPRINTK
@@ -36,6 +38,7 @@ struct backend_info {
 	char *mode;
 };
 
+static struct kmem_cache *blkif_cachep;
 static void connect(struct backend_info *);
 static int connect_ring(struct backend_info *);
 static void backend_changed(struct xenbus_watch *, const char **,
@@ -106,6 +109,154 @@ static void update_blkif_status(struct blkif_st *blkif)
 	}
 }
 
+struct blkif_st *blkif_alloc(domid_t domid)
+{
+	struct blkif_st *blkif;
+
+	blkif = kmem_cache_alloc(blkif_cachep, GFP_KERNEL);
+	if (!blkif)
+		return ERR_PTR(-ENOMEM);
+
+	memset(blkif, 0, sizeof(*blkif));
+	blkif->domid = domid;
+	spin_lock_init(&blkif->blk_ring_lock);
+	atomic_set(&blkif->refcnt, 1);
+	init_waitqueue_head(&blkif->wq);
+	blkif->st_print = jiffies;
+	init_waitqueue_head(&blkif->waiting_to_free);
+
+	return blkif;
+}
+
+static int map_frontend_page(struct blkif_st *blkif, unsigned long shared_page)
+{
+	struct gnttab_map_grant_ref op;
+
+	gnttab_set_map_op(&op, (unsigned long)blkif->blk_ring_area->addr,
+			  GNTMAP_host_map, shared_page, blkif->domid);
+
+	if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
+		BUG();
+
+	if (op.status) {
+		DPRINTK(" Grant table operation failure !\n");
+		return op.status;
+	}
+
+	blkif->shmem_ref = shared_page;
+	blkif->shmem_handle = op.handle;
+
+	return 0;
+}
+
+static void unmap_frontend_page(struct blkif_st *blkif)
+{
+	struct gnttab_unmap_grant_ref op;
+
+	gnttab_set_unmap_op(&op, (unsigned long)blkif->blk_ring_area->addr,
+			    GNTMAP_host_map, blkif->shmem_handle);
+
+	if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
+		BUG();
+}
+
+int blkif_map(struct blkif_st *blkif, unsigned long shared_page,
+	      unsigned int evtchn)
+{
+	int err;
+
+	/* Already connected through? */
+	if (blkif->irq)
+		return 0;
+
+	blkif->blk_ring_area = alloc_vm_area(PAGE_SIZE);
+	if (!blkif->blk_ring_area)
+		return -ENOMEM;
+
+	err = map_frontend_page(blkif, shared_page);
+	if (err) {
+		free_vm_area(blkif->blk_ring_area);
+		return err;
+	}
+
+	switch (blkif->blk_protocol) {
+	case BLKIF_PROTOCOL_NATIVE:
+	{
+		struct blkif_sring *sring;
+		sring = (struct blkif_sring *)blkif->blk_ring_area->addr;
+		BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE);
+		break;
+	}
+	case BLKIF_PROTOCOL_X86_32:
+	{
+		struct blkif_x86_32_sring *sring_x86_32;
+		sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring_area->addr;
+		BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE);
+		break;
+	}
+	case BLKIF_PROTOCOL_X86_64:
+	{
+		struct blkif_x86_64_sring *sring_x86_64;
+		sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring_area->addr;
+		BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE);
+		break;
+	}
+	default:
+		BUG();
+	}
+
+	err = bind_interdomain_evtchn_to_irqhandler(
+		blkif->domid, evtchn, blkif_be_int, 0, "blkif-backend", blkif);
+	if (err < 0) {
+		unmap_frontend_page(blkif);
+		free_vm_area(blkif->blk_ring_area);
+		blkif->blk_rings.common.sring = NULL;
+		return err;
+	}
+	blkif->irq = err;
+
+	return 0;
+}
+
+void blkif_disconnect(struct blkif_st *blkif)
+{
+	if (blkif->xenblkd) {
+		kthread_stop(blkif->xenblkd);
+		blkif->xenblkd = NULL;
+	}
+
+	atomic_dec(&blkif->refcnt);
+	wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0);
+	atomic_inc(&blkif->refcnt);
+
+	if (blkif->irq) {
+		unbind_from_irqhandler(blkif->irq, blkif);
+		blkif->irq = 0;
+	}
+
+	if (blkif->blk_rings.common.sring) {
+		unmap_frontend_page(blkif);
+		free_vm_area(blkif->blk_ring_area);
+		blkif->blk_rings.common.sring = NULL;
+	}
+}
+
+void blkif_free(struct blkif_st *blkif)
+{
+	if (!atomic_dec_and_test(&blkif->refcnt))
+		BUG();
+	kmem_cache_free(blkif_cachep, blkif);
+}
+
+int __init blkif_interface_init(void)
+{
+	blkif_cachep = kmem_cache_create("blkif_cache", sizeof(struct blkif_st),
+					 0, 0, NULL);
+	if (!blkif_cachep)
+		return -ENOMEM;
+
+	return 0;
+}
 
 /*
  *  sysfs interface for VBD I/O requests