author: David Howells <dhowells@redhat.com> 2006-09-27 01:50:16 -0700
committer: Linus Torvalds <torvalds@g5.osdl.org> 2006-09-27 08:26:14 -0700
commit: 5da6185bca064e35aa73a7c1f27488d2b96434f4
parent: 0ec76a110f432e98277e464b82ace8dd66571689
Commit Summary:
Diffstat:
1 file changed, 20 insertions, 0 deletions
diff --git a/fs/char_dev.c b/fs/char_dev.c
index 3483d3cf8087..0009346d827f 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -19,11 +19,30 @@
#include <linux/kobj_map.h>
#include <linux/cdev.h>
#include <linux/mutex.h>
+#include <linux/backing-dev.h>
#ifdef CONFIG_KMOD
#include <linux/kmod.h>
#endif
+/*
+ * capabilities for /dev/mem, /dev/kmem and similar directly mappable character
+ * devices
+ * - permits shared-mmap for read, write and/or exec
+ * - does not permit private mmap in NOMMU mode (can't do COW)
+ * - no readahead or I/O queue unplugging required
+ */
+struct backing_dev_info directly_mappable_cdev_bdi = {
+ .capabilities = (
+#ifdef CONFIG_MMU
+ /* permit private copies of the data to be taken */
+ BDI_CAP_MAP_COPY |
+#endif
+ /* permit direct mmap, for read, write or exec */
+ BDI_CAP_MAP_DIRECT |
+ BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP),
+};
+
static struct kobj_map *cdev_map;
static DEFINE_MUTEX(chrdevs_lock);
@@ -461,3 +480,4 @@ EXPORT_SYMBOL(cdev_del);
EXPORT_SYMBOL(cdev_add);
EXPORT_SYMBOL(register_chrdev);
EXPORT_SYMBOL(unregister_chrdev);
+EXPORT_SYMBOL(directly_mappable_cdev_bdi);