Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
  get rid of nameidata_dentry_drop_rcu() calling nameidata_drop_rcu()
  drop out of RCU in return_reval
  split do_revalidate() into RCU and non-RCU cases
  in do_lookup() split RCU and non-RCU cases of need_revalidate
  nothing in do_follow_link() is going to see RCU

1 files changed, 57 insertions, 65 deletions

diff --git a/fs/namei.c b/fs/namei.c
index ec4b2d0190a8..9e701e28a329 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -455,14 +455,6 @@ 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);
@@ -571,33 +563,15 @@ void release_open_intent(struct nameidata *nd)
         }
 }
 
-/*
- * 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)
+static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd)
 {
-        int status;
-
-        status = dentry->d_op->d_revalidate(dentry, nd);
-        if (status == -ECHILD) {
-                if (nameidata_dentry_drop_rcu(nd, dentry))
-                        return status;
-                status = dentry->d_op->d_revalidate(dentry, nd);
-        }
-
-        return status;
+        return dentry->d_op->d_revalidate(dentry, nd);
 }
 
-static inline struct dentry *
+static struct dentry *
 do_revalidate(struct dentry *dentry, struct nameidata *nd)
 {
-        int status;
-
-        status = d_revalidate(dentry, nd);
+        int status = d_revalidate(dentry, nd);
         if (unlikely(status <= 0)) {
                 /*
                  * The dentry failed validation.
@@ -606,24 +580,39 @@ do_revalidate(struct dentry *dentry, struct nameidata *nd)
                  * to return a fail status.
                  */
                 if (status < 0) {
-                        /* If we're in rcu-walk, we don't have a ref */
-                        if (!(nd->flags & LOOKUP_RCU))
-                                dput(dentry);
+                        dput(dentry);
                         dentry = ERR_PTR(status);
-
-                } else {
-                        /* Don't d_invalidate in rcu-walk mode */
-                        if (nameidata_dentry_drop_rcu_maybe(nd, dentry))
-                                return ERR_PTR(-ECHILD);
-                        if (!d_invalidate(dentry)) {
-                                dput(dentry);
-                                dentry = NULL;
-                        }
+                } else if (!d_invalidate(dentry)) {
+                        dput(dentry);
+                        dentry = NULL;
                 }
         }
         return dentry;
 }
 
+static inline struct dentry *
+do_revalidate_rcu(struct dentry *dentry, struct nameidata *nd)
+{
+        int status = d_revalidate(dentry, nd);
+        if (likely(status > 0))
+                return dentry;
+        if (status == -ECHILD) {
+                if (nameidata_dentry_drop_rcu(nd, dentry))
+                        return ERR_PTR(-ECHILD);
+                return do_revalidate(dentry, nd);
+        }
+        if (status < 0)
+                return ERR_PTR(status);
+        /* Don't d_invalidate in rcu-walk mode */
+        if (nameidata_dentry_drop_rcu(nd, dentry))
+                return ERR_PTR(-ECHILD);
+        if (!d_invalidate(dentry)) {
+                dput(dentry);
+                dentry = NULL;
+        }
+        return dentry;
+}
+
 static inline int need_reval_dot(struct dentry *dentry)
 {
         if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
@@ -668,9 +657,6 @@ 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;
         }
@@ -777,6 +763,8 @@ __do_follow_link(const struct path *link, struct nameidata *nd, void **p)
         int error;
         struct dentry *dentry = link->dentry;
 
+        BUG_ON(nd->flags & LOOKUP_RCU);
+
         touch_atime(link->mnt, dentry);
         nd_set_link(nd, NULL);
 
@@ -811,6 +799,11 @@ static inline int do_follow_link(struct path *path, struct nameidata *nd)
 {
         void *cookie;
         int err = -ELOOP;
+
+        /* We drop rcu-walk here */
+        if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry))
+                return -ECHILD;
+
         if (current->link_count >= MAX_NESTED_LINKS)
                 goto loop;
         if (current->total_link_count >= 40)
@@ -1255,9 +1248,15 @@ static int do_lookup(struct nameidata *nd, struct qstr *name,
                         return -ECHILD;
 
                 nd->seq = seq;
-                if (dentry->d_flags & DCACHE_OP_REVALIDATE)
-                        goto need_revalidate;
-done2:
+                if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
+                        dentry = do_revalidate_rcu(dentry, nd);
+                        if (!dentry)
+                                goto need_lookup;
+                        if (IS_ERR(dentry))
+                                goto fail;
+                        if (!(nd->flags & LOOKUP_RCU))
+                                goto done;
+                }
                 path->mnt = mnt;
                 path->dentry = dentry;
                 if (likely(__follow_mount_rcu(nd, path, inode, false)))
@@ -1270,8 +1269,13 @@ done2:
         if (!dentry)
                 goto need_lookup;
 found:
-        if (dentry->d_flags & DCACHE_OP_REVALIDATE)
-                goto need_revalidate;
+        if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
+                dentry = do_revalidate(dentry, nd);
+                if (!dentry)
+                        goto need_lookup;
+                if (IS_ERR(dentry))
+                        goto fail;
+        }
 done:
         path->mnt = mnt;
         path->dentry = dentry;
@@ -1313,16 +1317,6 @@ need_lookup:
         mutex_unlock(&dir->i_mutex);
         goto found;
 
-need_revalidate:
-        dentry = do_revalidate(dentry, nd);
-        if (!dentry)
-                goto need_lookup;
-        if (IS_ERR(dentry))
-                goto fail;
-        if (nd->flags & LOOKUP_RCU)
-                goto done2;
-        goto done;
-
 fail:
         return PTR_ERR(dentry);
 }
@@ -1419,9 +1413,6 @@ exec_again:
                         goto out_dput;
 
                 if (inode->i_op->follow_link) {
-                        /* We commonly drop rcu-walk here */
-                        if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry))
-                                return -ECHILD;
                         BUG_ON(inode != next.dentry->d_inode);
                         err = do_follow_link(&next, nd);
                         if (err)
@@ -1467,8 +1458,6 @@ last_component:
                         break;
                 if (inode && unlikely(inode->i_op->follow_link) &&
                     (lookup_flags & LOOKUP_FOLLOW)) {
-                        if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry))
-                                return -ECHILD;
                         BUG_ON(inode != next.dentry->d_inode);
                         err = do_follow_link(&next, nd);
                         if (err)
@@ -1504,12 +1493,15 @@ return_reval:
                  * We may need to check the cached dentry for staleness.
                  */
                 if (need_reval_dot(nd->path.dentry)) {
+                        if (nameidata_drop_rcu_last_maybe(nd))
+                                return -ECHILD;
                         /* Note: we do not d_invalidate() */
                         err = d_revalidate(nd->path.dentry, nd);
                         if (!err)
                                 err = -ESTALE;
                         if (err < 0)
                                 break;
+                        return 0;
                 }
 return_base:
                 if (nameidata_drop_rcu_last_maybe(nd))