1 files changed, 82 insertions, 83 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 7d77f24d32a9..a4689eb2df28 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);
@@ -561,39 +553,25 @@ static inline int nameidata_drop_rcu_last_maybe(struct nameidata *nd)
  */
 void release_open_intent(struct nameidata *nd)
 {
-        if (nd->intent.open.file->f_path.dentry == NULL)
-                put_filp(nd->intent.open.file);
-        else
-                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;
+        struct file *file = nd->intent.open.file;
 
-        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);
+        if (file && !IS_ERR(file)) {
+                if (file->f_path.dentry == NULL)
+                        put_filp(file);
+                else
+                        fput(file);
         }
+}
 
-        return status;
+static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd)
+{
+        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.
@@ -602,24 +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)))
@@ -664,9 +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;
         }
@@ -773,6 +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);
 
@@ -803,10 +795,16 @@ __do_follow_link(const struct path *link, struct nameidata *nd, void **p)
  * Without that kind of total limit, nasty chains of consecutive
  * symlinks can cause almost arbitrarily long lookups. 
  */
-static inline int do_follow_link(struct path *path, struct nameidata *nd)
+static inline int do_follow_link(struct inode *inode, 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;
+        BUG_ON(inode != path->dentry->d_inode);
+
         if (current->link_count >= MAX_NESTED_LINKS)
                 goto loop;
         if (current->total_link_count >= 40)
@@ -1251,9 +1249,15 @@ 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)))
@@ -1266,8 +1270,13 @@ 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;
@@ -1309,16 +1318,6 @@ 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);
 }
@@ -1415,11 +1414,7 @@ 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);
+                        err = do_follow_link(inode, &next, nd);
                         if (err)
                                 goto return_err;
                         nd->inode = nd->path.dentry->d_inode;
@@ -1463,10 +1458,7 @@ 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);
+                        err = do_follow_link(inode, &next, nd);
                         if (err)
                                 goto return_err;
                         nd->inode = nd->path.dentry->d_inode;
@@ -1500,12 +1492,15 @@ 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))
@@ -1551,6 +1546,7 @@ static int path_walk(const char *name, struct nameidata *nd)
                 /* nd->path had been dropped */
                 current->total_link_count = 0;
                 nd->path = save;
+                nd->inode = save.dentry->d_inode;
                 path_get(&nd->path);
                 nd->flags |= LOOKUP_REVAL;
                 result = link_path_walk(name, nd);
@@ -2265,8 +2261,6 @@ static struct file *finish_open(struct nameidata *nd,
         return filp;
 
 exit:
-        if (!IS_ERR(nd->intent.open.file))
-                release_open_intent(nd);
         path_put(&nd->path);
         return ERR_PTR(error);
 }
@@ -2389,8 +2383,6 @@ exit_mutex_unlock:
 exit_dput:
         path_put_conditional(path, nd);
 exit:
-        if (!IS_ERR(nd->intent.open.file))
-                release_open_intent(nd);
         path_put(&nd->path);
         return ERR_PTR(error);
 }
@@ -2464,21 +2456,29 @@ struct file *do_filp_open(int dfd, const char *pathname,
         /* !O_CREAT, simple open */
         error = do_path_lookup(dfd, pathname, flags, &nd);
         if (unlikely(error))
-                goto out_filp;
+                goto out_filp2;
         error = -ELOOP;
         if (!(nd.flags & LOOKUP_FOLLOW)) {
                 if (nd.inode->i_op->follow_link)
-                        goto out_path;
+                        goto out_path2;
         }
         error = -ENOTDIR;
         if (nd.flags & LOOKUP_DIRECTORY) {
                 if (!nd.inode->i_op->lookup)
-                        goto out_path;
+                        goto out_path2;
         }
         audit_inode(pathname, nd.path.dentry);
         filp = finish_open(&nd, open_flag, acc_mode);
+out2:
+        release_open_intent(&nd);
         return filp;
 
+out_path2:
+        path_put(&nd.path);
+out_filp2:
+        filp = ERR_PTR(error);
+        goto out2;
+
 creat:
         /* OK, have to create the file. Find the parent. */
         error = path_init_rcu(dfd, pathname,
@@ -2553,6 +2553,7 @@ out:
                 path_put(&nd.root);
         if (filp == ERR_PTR(-ESTALE) && !(flags & LOOKUP_REVAL))
                 goto reval;
+        release_open_intent(&nd);
         return filp;
 
 exit_dput:
@@ -2560,8 +2561,6 @@ exit_dput:
 out_path:
         path_put(&nd.path);
 out_filp:
-        if (!IS_ERR(nd.intent.open.file))
-                release_open_intent(&nd);
         filp = ERR_PTR(error);
         goto out;
 }