[Xen-changelog] Cleanup backend block device logic under save/restore; this should

[Xen patchbot -unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User smh22@xxxxxxxxxxxxxxxxxxxx
# Node ID 37b93f40eb0a5c2bccff54d9b6b8357ee6b00864
# Parent  450c562b76aab05d8330a2337628b68766e58e6c
Cleanup backend block device logic under save/restore; this should 
fix the issues some people have seen with segfaults in vbd_translate 
and/or user-space hangs. 

Signed-off-by: Steven Hand <steven@xxxxxxxxxxxxx>

diff -r 450c562b76aa -r 37b93f40eb0a 
linux-2.6-xen-sparse/drivers/xen/blkback/common.h
--- a/linux-2.6-xen-sparse/drivers/xen/blkback/common.h Tue Nov 29 13:37:24 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/blkback/common.h Tue Nov 29 13:50:30 2005
@@ -38,6 +38,8 @@
        struct block_device *bdev;
 }; 
 
+struct backend_info; 
+
 typedef struct blkif_st {
        /* Unique identifier for this interface. */
        domid_t           domid;
@@ -48,8 +50,10 @@
        /* Comms information. */
        blkif_back_ring_t blk_ring;
        struct vm_struct *blk_ring_area;
-       /* VBDs attached to this interface. */
+       /* The VBD attached to this interface. */
        struct vbd        vbd;
+       /* Back pointer to the backend_info. */
+       struct backend_info *be; 
        /* Private fields. */
        enum { DISCONNECTED, CONNECTED } status;
 #ifdef CONFIG_XEN_BLKDEV_TAP_BE
@@ -103,6 +107,8 @@
 
 irqreturn_t blkif_be_int(int irq, void *dev_id, struct pt_regs *regs);
 
+void update_blkif_status(blkif_t *blkif); 
+
 #endif /* __BLKIF__BACKEND__COMMON_H__ */
 
 /*
diff -r 450c562b76aa -r 37b93f40eb0a 
linux-2.6-xen-sparse/drivers/xen/blkback/interface.c
--- a/linux-2.6-xen-sparse/drivers/xen/blkback/interface.c      Tue Nov 29 
13:37:24 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/blkback/interface.c      Tue Nov 29 
13:50:30 2005
@@ -112,7 +112,9 @@
 
        blkif->irq = bind_evtchn_to_irqhandler(
                blkif->evtchn, blkif_be_int, 0, "blkif-backend", blkif);
-       blkif->status = CONNECTED;
+
+       /* We're potentially connected now */
+       update_blkif_status(blkif); 
 
        return 0;
 }
diff -r 450c562b76aa -r 37b93f40eb0a 
linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c
--- a/linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c Tue Nov 29 13:37:24 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c Tue Nov 29 13:50:30 2005
@@ -50,6 +50,16 @@
                            unsigned int);
 
 
+void update_blkif_status(blkif_t *blkif)
+{ 
+       if(blkif->irq && blkif->vbd.bdev) {
+               blkif->status = CONNECTED; 
+               (void)blkif_be_int(0, blkif, NULL); 
+       }
+       maybe_connect(blkif->be); 
+}
+
+
 static ssize_t show_physical_device(struct device *_dev, char *buf)
 {
        struct xenbus_device *dev = to_xenbus_device(_dev);
@@ -81,6 +91,7 @@
                be->backend_watch.node = NULL;
        }
        if (be->blkif) {
+               be->blkif->status = DISCONNECTED; 
                blkif_put(be->blkif);
                be->blkif = NULL;
        }
@@ -122,6 +133,9 @@
                xenbus_dev_fatal(dev, err, "creating block interface");
                goto fail;
        }
+
+       /* setup back pointer */
+       be->blkif->be = be; 
 
        err = xenbus_watch_path2(dev, dev->nodename, "physical-device",
                                 &be->backend_watch, backend_changed);
@@ -209,7 +223,8 @@
                device_create_file(&dev->dev, &dev_attr_physical_device);
                device_create_file(&dev->dev, &dev_attr_mode);
 
-               maybe_connect(be);
+               /* We're potentially connected now */
+               update_blkif_status(be->blkif); 
        }
 }
 
@@ -235,7 +250,7 @@
                if (err) {
                        return;
                }
-               maybe_connect(be);
+               update_blkif_status(be->blkif); 
                break;
 
        case XenbusStateClosing:

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