Merge branch 'stable/for-jens-4.2' of git://git.kernel.org/pub/scm/linux/kernel/git...

[cascardo/linux.git] / drivers / block / xen-blkback / blkback.c

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 713fc9f..2126842 100644 (file)
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -83,6 +83,13 @@ module_param_named(max_persistent_grants, xen_blkif_max_pgrants, int, 0644);
 MODULE_PARM_DESC(max_persistent_grants,
                  "Maximum number of grants to map persistently");
 
+/*
+ * Maximum order of pages to be used for the shared ring between front and
+ * backend, 4KB page granularity is used.
+ */
+unsigned int xen_blkif_max_ring_order = XENBUS_MAX_RING_PAGE_ORDER;
+module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, S_IRUGO);
+MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
 /*
  * The LRU mechanism to clean the lists of persistent grants needs to
  * be executed periodically. The time interval between consecutive executions
@@ -1438,6 +1445,12 @@ static int __init xen_blkif_init(void)
        if (!xen_domain())
                return -ENODEV;
 
+       if (xen_blkif_max_ring_order > XENBUS_MAX_RING_PAGE_ORDER) {
+               pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
+                       xen_blkif_max_ring_order, XENBUS_MAX_RING_PAGE_ORDER);
+               xen_blkif_max_ring_order = XENBUS_MAX_RING_PAGE_ORDER;
+       }
+
        rc = xen_blkif_interface_init();
        if (rc)
                goto failed_init;