[PATCH] r/o bind mounts: track numbers of writers to mounts

[linux-2.6-omap-h63xx.git] / include / linux / mount.h

diff --git a/include/linux/mount.h b/include/linux/mount.h
index 2eecd2c8c760fbfde8225d756d200c01a2569c76..8c8e94369ac8ba096d67c2cc1d85ec97127b6956 100644 (file)
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -14,6 +14,7 @@
 
 #include <linux/types.h>
 #include <linux/list.h>
+#include <linux/nodemask.h>
 #include <linux/spinlock.h>
 #include <asm/atomic.h>
 
@@ -30,6 +31,7 @@ struct mnt_namespace;
 #define MNT_RELATIME   0x20
 
 #define MNT_SHRINKABLE 0x100
+#define MNT_IMBALANCED_WRITE_COUNT     0x200 /* just for debugging */
 
 #define MNT_SHARED     0x1000  /* if the vfsmount is a shared mount */
 #define MNT_UNBINDABLE 0x2000  /* if the vfsmount is a unbindable mount */
@@ -62,6 +64,11 @@ struct vfsmount {
        int mnt_expiry_mark;            /* true if marked for expiry */
        int mnt_pinned;
        int mnt_ghosts;
+       /*
+        * This value is not stable unless all of the mnt_writers[] spinlocks
+        * are held, and all mnt_writer[]s on this mount have 0 as their ->count
+        */
+       atomic_t __mnt_writers;
 };
 
 static inline struct vfsmount *mntget(struct vfsmount *mnt)