cifs: don't allow mmap'ed pages to be dirtied while under writeback (try #3)

[pandora-kernel.git] / fs / namei.c

diff --git a/fs/namei.c b/fs/namei.c
index d0066e1..e6cd611 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -70,7 +70,7 @@
  * name indicated by the symlink. The old code always complained that the
  * name already exists, due to not following the symlink even if its target
  * is nonexistent.  The new semantics affects also mknod() and link() when
- * the name is a symlink pointing to a non-existant name.
+ * the name is a symlink pointing to a non-existent name.
  *
  * I don't know which semantics is the right one, since I have no access
  * to standards. But I found by trial that HP-UX 9.0 has the full "new"
@@ -992,6 +992,12 @@ int follow_down_one(struct path *path)
        return 0;
 }
 
+static inline bool managed_dentry_might_block(struct dentry *dentry)
+{
+       return (dentry->d_flags & DCACHE_MANAGE_TRANSIT &&
+               dentry->d_op->d_manage(dentry, true) < 0);
+}
+
 /*
  * Skip to top of mountpoint pile in rcuwalk mode.  We abort the rcu-walk if we
  * meet a managed dentry and we're not walking to "..".  True is returned to
@@ -1000,19 +1006,26 @@ int follow_down_one(struct path *path)
 static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
                               struct inode **inode, bool reverse_transit)
 {
-       while (d_mountpoint(path->dentry)) {
+       for (;;) {
                struct vfsmount *mounted;
-               if (unlikely(path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) &&
-                   !reverse_transit &&
-                   path->dentry->d_op->d_manage(path->dentry, true) < 0)
+               /*
+                * Don't forget we might have a non-mountpoint managed dentry
+                * that wants to block transit.
+                */
+               *inode = path->dentry->d_inode;
+               if (!reverse_transit &&
+                    unlikely(managed_dentry_might_block(path->dentry)))
                        return false;
+
+               if (!d_mountpoint(path->dentry))
+                       break;
+
                mounted = __lookup_mnt(path->mnt, path->dentry, 1);
                if (!mounted)
                        break;
                path->mnt = mounted;
                path->dentry = mounted->mnt_root;
                nd->seq = read_seqcount_begin(&path->dentry->d_seq);
-               *inode = path->dentry->d_inode;
        }
 
        if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT))