1 files changed, 35 insertions, 2 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 998d5316921a..7d694194024a 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2202,6 +2202,8 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
         struct file *filp;
         struct inode *inode;
         int symlink_ok = 0;
+        struct path save_parent = { .dentry = NULL, .mnt = NULL };
+        bool retried = false;
         int error;
 
         nd->flags &= ~LOOKUP_PARENT;
@@ -2267,6 +2269,7 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
         if (nd->last.name[nd->last.len])
                 goto exit;
 
+retry_lookup:
         mutex_lock(&dir->d_inode->i_mutex);
 
         dentry = lookup_hash(nd);
@@ -2349,12 +2352,21 @@ finish_lookup:
                 return NULL;
         }
 
-        path_to_nameidata(path, nd);
+        if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) {
+                path_to_nameidata(path, nd);
+        } else {
+                save_parent.dentry = nd->path.dentry;
+                save_parent.mnt = mntget(path->mnt);
+                nd->path.dentry = path->dentry;
+
+        }
         nd->inode = inode;
         /* Why this, you ask?  _Now_ we might have grown LOOKUP_JUMPED... */
         error = complete_walk(nd);
-        if (error)
+        if (error) {
+                path_put(&save_parent);
                 return ERR_PTR(error);
+        }
         error = -EISDIR;
         if ((open_flag & O_CREAT) && S_ISDIR(nd->inode->i_mode))
                 goto exit;
@@ -2377,6 +2389,20 @@ common:
         if (error)
                 goto exit;
         filp = nameidata_to_filp(nd);
+        if (filp == ERR_PTR(-EOPENSTALE) && save_parent.dentry && !retried) {
+                BUG_ON(save_parent.dentry != dir);
+                path_put(&nd->path);
+                nd->path = save_parent;
+                nd->inode = dir->d_inode;
+                save_parent.mnt = NULL;
+                save_parent.dentry = NULL;
+                if (want_write) {
+                        mnt_drop_write(nd->path.mnt);
+                        want_write = 0;
+                }
+                retried = true;
+                goto retry_lookup;
+        }
         if (!IS_ERR(filp)) {
                 error = ima_file_check(filp, op->acc_mode);
                 if (error) {
@@ -2396,6 +2422,7 @@ common:
 out:
         if (want_write)
                 mnt_drop_write(nd->path.mnt);
+        path_put(&save_parent);
         terminate_walk(nd);
         return filp;
 
@@ -2459,6 +2486,12 @@ out:
         if (base)
                 fput(base);
         release_open_intent(nd);
+        if (filp == ERR_PTR(-EOPENSTALE)) {
+                if (flags & LOOKUP_RCU)
+                        filp = ERR_PTR(-ECHILD);
+                else
+                        filp = ERR_PTR(-ESTALE);
+        }
         return filp;
 
 out_filp: