Merge branch 'vfs-scale-working' of git://git.kernel.org/pub/scm/linux/kernel/git/npiggin/linux-npiggin

* 'vfs-scale-working' of git://git.kernel.org/pub/scm/linux/kernel/git/npiggin/linux-npiggin:
  fs: fix do_last error case when need_reval_dot
  nfs: add missing rcu-walk check
  fs: hlist UP debug fixup
  fs: fix dropping of rcu-walk from force_reval_path
  fs: force_reval_path drop rcu-walk before d_invalidate
  fs: small rcu-walk documentation fixes

Fixed up trivial conflicts in Documentation/filesystems/porting

1 files changed, 24 insertions, 4 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 0b14f6910fc6..86643302079e 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -479,6 +479,14 @@ static int nameidata_dentry_drop_rcu(struct nameidata *nd, struct dentry *dentry
         struct fs_struct *fs = current->fs;
         struct dentry *parent = nd->path.dentry;
 
+        /*
+         * It can be possible to revalidate the dentry that we started
+         * the path walk with. force_reval_path may also revalidate the
+         * dentry already committed to the nameidata.
+         */
+        if (unlikely(parent == dentry))
+                return nameidata_drop_rcu(nd);
+
         BUG_ON(!(nd->flags & LOOKUP_RCU));
         if (nd->root.mnt) {
                 spin_lock(&fs->lock);
@@ -583,6 +591,13 @@ void release_open_intent(struct nameidata *nd)
                 fput(nd->intent.open.file);
 }
 
+/*
+ * Call d_revalidate and handle filesystems that request rcu-walk
+ * to be dropped. This may be called and return in rcu-walk mode,
+ * regardless of success or error. If -ECHILD is returned, the caller
+ * must return -ECHILD back up the path walk stack so path walk may
+ * be restarted in ref-walk mode.
+ */
 static int d_revalidate(struct dentry *dentry, struct nameidata *nd)
 {
         int status;
@@ -673,6 +688,9 @@ force_reval_path(struct path *path, struct nameidata *nd)
                 return 0;
 
         if (!status) {
+                /* Don't d_invalidate in rcu-walk mode */
+                if (nameidata_drop_rcu(nd))
+                        return -ECHILD;
                 d_invalidate(dentry);
                 status = -ESTALE;
         }
@@ -2105,11 +2123,13 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
                 dir = nd->path.dentry;
         case LAST_DOT:
                 if (need_reval_dot(dir)) {
-                        error = d_revalidate(nd->path.dentry, nd);
-                        if (!error)
-                                error = -ESTALE;
-                        if (error < 0)
+                        int status = d_revalidate(nd->path.dentry, nd);
+                        if (!status)
+                                status = -ESTALE;
+                        if (status < 0) {
+                                error = status;
                                 goto exit;
+                        }
                 }
                 /* fallthrough */
         case LAST_ROOT: