linux: fix blkback/blktap2 interaction

blkback's page map code needs to be accessible to both blkback and
blktap2, irrespective of whether either or both are modules. The
most immediate solution is to break it out into a separate, library-
like component that doesn't need building if either of the two
consumers is configured off, and that gets built as a module if both
consumers are modules.

Also fix the dummy implementation of blkback_pagemap_read(), since
using BUG() there doesn't compile.

Signed-off-by: Jan Beulich <jbeulich@novell.com>

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index e9558ddc71db0305ed5891b0bd6a58f91a9e51cd..a153b5a486b6e947ebff87aa5e7d8be5906462fb 100644 (file)
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -75,6 +75,11 @@ config XEN_BLKDEV_TAP2
           as files, in memory, or on other hosts across the network.  This 
          driver can safely coexist with the existing blockback driver.
 
+config XEN_BLKBACK_PAGEMAP
+       tristate
+       depends on XEN_BLKDEV_BACKEND != n && XEN_BLKDEV_TAP2 != n
+       default XEN_BLKDEV_BACKEND || XEN_BLKDEV_TAP2
+
 config XEN_NETDEV_BACKEND
        tristate "Network-device backend driver"
         depends on XEN_BACKEND && NET

diff --git a/drivers/xen/blkback/Makefile b/drivers/xen/blkback/Makefile
index 466cdf0d2381d6f8f2f493b0b3a9223c9afda742..48e3e22111eecbc88af6435618b2931ea7dc394c 100644 (file)
--- a/drivers/xen/blkback/Makefile
+++ b/drivers/xen/blkback/Makefile
@@ -1,3 +1,4 @@
 obj-$(CONFIG_XEN_BLKDEV_BACKEND) := blkbk.o
+obj-$(CONFIG_XEN_BLKBACK_PAGEMAP) += blkback-pagemap.o
 
-blkbk-y        := blkback.o xenbus.o interface.o vbd.o blkback-pagemap.o
+blkbk-y        := blkback.o xenbus.o interface.o vbd.o

diff --git a/drivers/xen/blkback/blkback-pagemap.c b/drivers/xen/blkback/blkback-pagemap.c
index 77550b4ac2889f97f34107481df86c764b088054..f7d16d892293513a473e09564812526ebfc10757 100644 (file)
--- a/drivers/xen/blkback/blkback-pagemap.c
+++ b/drivers/xen/blkback/blkback-pagemap.c
@@ -1,4 +1,4 @@
-#include "common.h"
+#include <linux/module.h>
 #include "blkback-pagemap.h"
 
 static int blkback_pagemap_size;
@@ -22,6 +22,7 @@ blkback_pagemap_init(int pages)
        blkback_pagemap_size = pages;
        return 0;
 }
+EXPORT_SYMBOL_GPL(blkback_pagemap_init);
 
 void
 blkback_pagemap_set(int idx, struct page *page,
@@ -46,6 +47,7 @@ blkback_pagemap_set(int idx, struct page *page,
        entry->busid = busid;
        entry->gref  = gref;
 }
+EXPORT_SYMBOL_GPL(blkback_pagemap_set);
 
 void
 blkback_pagemap_clear(struct page *page)
@@ -67,6 +69,7 @@ blkback_pagemap_clear(struct page *page)
 
        memset(entry, 0, sizeof(*entry));
 }
+EXPORT_SYMBOL_GPL(blkback_pagemap_clear);
 
 struct blkback_pagemap
 blkback_pagemap_read(struct page *page)
@@ -89,3 +92,5 @@ blkback_pagemap_read(struct page *page)
        return *entry;
 }
 EXPORT_SYMBOL(blkback_pagemap_read);
+
+MODULE_LICENSE("Dual BSD/GPL");

diff --git a/drivers/xen/blkback/blkback-pagemap.h b/drivers/xen/blkback/blkback-pagemap.h
index 5e6809fcd6149e13db7be0bcd7c65dbffa2a2162..0becf22d0f45dffdacdbe596e7d091c16521c387 100644 (file)
--- a/drivers/xen/blkback/blkback-pagemap.h
+++ b/drivers/xen/blkback/blkback-pagemap.h
@@ -1,6 +1,7 @@
 #ifndef _BLKBACK_PAGEMAP_H_
 #define _BLKBACK_PAGEMAP_H_
 
+#include <linux/mm.h>
 #include <xen/interface/xen.h>
 #include <xen/interface/grant_table.h>
 
@@ -12,6 +13,25 @@ struct blkback_pagemap {
        grant_ref_t      gref;
 };
 
+#if defined(CONFIG_XEN_BLKBACK_PAGEMAP) || defined(CONFIG_XEN_BLKBACK_PAGEMAP_MODULE)
+
+int blkback_pagemap_init(int);
+void blkback_pagemap_set(int, struct page *, domid_t, busid_t, grant_ref_t);
+void blkback_pagemap_clear(struct page *);
 struct blkback_pagemap blkback_pagemap_read(struct page *);
 
+#else /* CONFIG_XEN_BLKBACK_PAGEMAP */
+
+static inline int blkback_pagemap_init(int pages) { return 0; }
+static inline void blkback_pagemap_set(int idx, struct page *page, domid_t dom,
+                                      busid_t bus, grant_ref_t gnt) {}
+static inline void blkback_pagemap_clear(struct page *page) {}
+static inline struct blkback_pagemap blkback_pagemap_read(struct page *page)
+{
+       BUG();
+       return (struct blkback_pagemap){-1, -1, -1};
+}
+
+#endif /* CONFIG_XEN_BLKBACK_PAGEMAP */
+
 #endif

diff --git a/drivers/xen/blkback/common.h b/drivers/xen/blkback/common.h
index 709b7a9c4d7d85274ac982f06a4bf55a1c792378..6dff5e7612977d708cd9b6a85d42f0d2d522c335 100644 (file)
--- a/drivers/xen/blkback/common.h
+++ b/drivers/xen/blkback/common.h
@@ -138,8 +138,4 @@ int blkif_schedule(void *arg);
 int blkback_barrier(struct xenbus_transaction xbt,
                    struct backend_info *be, int state);
 
-int blkback_pagemap_init(int);
-void blkback_pagemap_set(int, struct page *, domid_t, busid_t, grant_ref_t);
-void blkback_pagemap_clear(struct page *);
-
 #endif /* __BLKIF__BACKEND__COMMON_H__ */

diff --git a/drivers/xen/blktap2/device.c b/drivers/xen/blktap2/device.c
index 2137b7db585a3505a01697583d683ec04ff4668c..afbdcd545dc83a7c42ca03f390b43c1bcb614c81 100644 (file)
--- a/drivers/xen/blktap2/device.c
+++ b/drivers/xen/blktap2/device.c
@@ -13,13 +13,7 @@
 
 #include "blktap.h"
 
-#if defined(CONFIG_XEN_BLKDEV_BACKEND) || \
-    (defined(CONFIG_XEN_BLKDEV_BACKEND_MODULE) && defined(MODULE))
 #include "../blkback/blkback-pagemap.h"
-#else
-struct blkback_pagemap { };
-#define blkback_pagemap_read(page) BUG();
-#endif
 
 #if 0
 #define DPRINTK_IOCTL(_f, _a...) printk(KERN_ALERT _f, ## _a)