xen/privcmd: create address space to allow writable mmaps
These are necessary to allow writeable mmap of the privcmd node to
succeed without being marked read-only for writenotify purposes. Which
in turn is necessary to allow mappings of foreign guest pages
[ Impact: bugfix: allow writable mappings ]
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
diff --git a/drivers/xen/xenfs/super.c b/drivers/xen/xenfs/super.c
index 8c74628..23f1cca 100644
--- a/drivers/xen/xenfs/super.c
+++ b/drivers/xen/xenfs/super.c
@@ -12,6 +12,8 @@
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/magic.h>
+#include <linux/mm.h>
+#include <linux/backing-dev.h>
#include <xen/xen.h>
@@ -22,12 +24,30 @@
MODULE_DESCRIPTION("Xen filesystem");
MODULE_LICENSE("GPL");
+static int xenfs_set_page_dirty(struct page *page)
+{
+ if (!PageDirty(page))
+ SetPageDirty(page);
+ return 0;
+}
+
+static const struct address_space_operations xenfs_aops = {
+ .set_page_dirty = xenfs_set_page_dirty,
+};
+
+static struct backing_dev_info xenfs_backing_dev_info = {
+ .ra_pages = 0, /* No readahead */
+ .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
+};
+
static struct inode *xenfs_make_inode(struct super_block *sb, int mode)
{
struct inode *ret = new_inode(sb);
if (ret) {
ret->i_mode = mode;
+ ret->i_mapping->a_ops = &xenfs_aops;
+ ret->i_mapping->backing_dev_info = &xenfs_backing_dev_info;
ret->i_uid = ret->i_gid = 0;
ret->i_blocks = 0;
ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
@@ -119,11 +139,25 @@
static int __init xenfs_init(void)
{
- if (xen_domain())
- return register_filesystem(&xenfs_type);
+ int err;
+ if (!xen_domain()) {
+ printk(KERN_INFO "xenfs: not registering filesystem on non-xen platform\n");
+ return 0;
+ }
- printk(KERN_INFO "XENFS: not registering filesystem on non-xen platform\n");
- return 0;
+ err = register_filesystem(&xenfs_type);
+ if (err) {
+ printk(KERN_ERR "xenfs: Unable to register filesystem!\n");
+ goto out;
+ }
+
+ err = bdi_init(&xenfs_backing_dev_info);
+ if (err)
+ unregister_filesystem(&xenfs_type);
+
+ out:
+
+ return err;
}
static void __exit xenfs_exit(void)