1 files changed, 151 insertions, 0 deletions

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