omap3: Add external VBUS power switch and overcurrent detect onIGEP v2 board

[karo-tx-linux.git] / fs / pnode.c

diff --git a/fs/pnode.c b/fs/pnode.c
index 8d5f392ec3d39fa12a025ec3a6045b7ef8f790a4..8066b8dd748f6800a09694ee62c2a0b33c97d20a 100644 (file)
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -86,7 +86,7 @@ static int do_make_slave(struct vfsmount *mnt)
 
        /*
         * slave 'mnt' to a peer mount that has the
-        * same root dentry. If none is available than
+        * same root dentry. If none is available then
         * slave it to anything that is available.
         */
        while ((peer_mnt = next_peer(peer_mnt)) != mnt &&
@@ -126,6 +126,9 @@ static int do_make_slave(struct vfsmount *mnt)
        return 0;
 }
 
+/*
+ * vfsmount lock must be held for write
+ */
 void change_mnt_propagation(struct vfsmount *mnt, int type)
 {
        if (type == MS_SHARED) {
@@ -147,6 +150,11 @@ void change_mnt_propagation(struct vfsmount *mnt, int type)
  * get the next mount in the propagation tree.
  * @m: the mount seen last
  * @origin: the original mount from where the tree walk initiated
+ *
+ * Note that peer groups form contiguous segments of slave lists.
+ * We rely on that in get_source() to be able to find out if
+ * vfsmount found while iterating with propagation_next() is
+ * a peer of one we'd found earlier.
  */
 static struct vfsmount *propagation_next(struct vfsmount *m,
                                         struct vfsmount *origin)
@@ -186,10 +194,6 @@ static struct vfsmount *get_source(struct vfsmount *dest,
 {
        struct vfsmount *p_last_src = NULL;
        struct vfsmount *p_last_dest = NULL;
-       *type = CL_PROPAGATION;
-
-       if (IS_MNT_SHARED(dest))
-               *type |= CL_MAKE_SHARED;
 
        while (last_dest != dest->mnt_master) {
                p_last_dest = last_dest;
@@ -202,13 +206,18 @@ static struct vfsmount *get_source(struct vfsmount *dest,
                do {
                        p_last_dest = next_peer(p_last_dest);
                } while (IS_MNT_NEW(p_last_dest));
+               /* is that a peer of the earlier? */
+               if (dest == p_last_dest) {
+                       *type = CL_MAKE_SHARED;
+                       return p_last_src;
+               }
        }
-
-       if (dest != p_last_dest) {
-               *type |= CL_SLAVE;
-               return last_src;
-       } else
-               return p_last_src;
+       /* slave of the earlier, then */
+       *type = CL_SLAVE;
+       /* beginning of peer group among the slaves? */
+       if (IS_MNT_SHARED(dest))
+               *type |= CL_MAKE_SHARED;
+       return last_src;
 }
 
 /*
@@ -264,12 +273,12 @@ int propagate_mnt(struct vfsmount *dest_mnt, struct dentry *dest_dentry,
                prev_src_mnt  = child;
        }
 out:
-       spin_lock(&vfsmount_lock);
+       br_write_lock(vfsmount_lock);
        while (!list_empty(&tmp_list)) {
                child = list_first_entry(&tmp_list, struct vfsmount, mnt_hash);
                umount_tree(child, 0, &umount_list);
        }
-       spin_unlock(&vfsmount_lock);
+       br_write_unlock(vfsmount_lock);
        release_mounts(&umount_list);
        return ret;
 }
@@ -290,6 +299,8 @@ static inline int do_refcount_check(struct vfsmount *mnt, int count)
  * other mounts its parent propagates to.
  * Check if any of these mounts that **do not have submounts**
  * have more references than 'refcnt'. If so return busy.
+ *
+ * vfsmount lock must be held for read or write
  */
 int propagate_mount_busy(struct vfsmount *mnt, int refcnt)
 {
@@ -347,6 +358,8 @@ static void __propagate_umount(struct vfsmount *mnt)
  * collect all mounts that receive propagation from the mount in @list,
  * and return these additional mounts in the same list.
  * @list: the list of mounts to be unmounted.
+ *
+ * vfsmount lock must be held for write
  */
 int propagate_umount(struct list_head *list)
 {