new helpers: lock_mount_hash/unlock_mount_hash

aka br_write_{lock,unlock} of vfsmount_lock.  Inlines in fs/mount.h,
vfsmount_lock extern moved over there as well.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 13 insertions, 0 deletions

diff --git a/fs/mount.h b/fs/mount.h
index 3168dc41bad..7076f25af35 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -1,6 +1,7 @@
 #include <linux/mount.h>
 #include <linux/seq_file.h>
 #include <linux/poll.h>
+#include <linux/lglock.h>
 
 struct mnt_namespace {
 	atomic_t		count;
@@ -83,6 +84,18 @@ static inline void get_mnt_ns(struct mnt_namespace *ns)
 	atomic_inc(&ns->count);
 }
 
+extern struct lglock vfsmount_lock;
+
+static inline void lock_mount_hash(void)
+{
+	br_write_lock(&vfsmount_lock);
+}
+
+static inline void unlock_mount_hash(void)
+{
+	br_write_unlock(&vfsmount_lock);
+}
+
 struct proc_mounts {
 	struct seq_file m;
 	struct mnt_namespace *ns;