jffs2: reduce the breakage on recovery from halfway failed rename()

d_instantiate(new_dentry, old_inode) is absolutely wrong thing to
do - it will oops if new_dentry used to be positive, for starters.
What we need is d_invalidate() the target and be done with that.

Cc: stable@vger.kernel.org # v3.18+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 8 insertions, 3 deletions

diff --git a/fs/jffs2/dir.c b/fs/jffs2/dir.c
index d211b8e18566..30c4c9ebb693 100644
--- a/fs/jffs2/dir.c
+++ b/fs/jffs2/dir.c
@@ -843,9 +843,14 @@ static int jffs2_rename (struct inode *old_dir_i, struct dentry *old_dentry,
 
                 pr_notice("%s(): Link succeeded, unlink failed (err %d). You now have a hard link\n",
                           __func__, ret);
-                /* Might as well let the VFS know */
-                d_instantiate(new_dentry, d_inode(old_dentry));
-                ihold(d_inode(old_dentry));
+                /*
+                 * We can't keep the target in dcache after that.
+                 * For one thing, we can't afford dentry aliases for directories.
+                 * For another, if there was a victim, we _can't_ set new inode
+                 * for that sucker and we have to trigger mount eviction - the
+                 * caller won't do it on its own since we are returning an error.
+                 */
+                d_invalidate(new_dentry);
                 new_dir_i->i_mtime = new_dir_i->i_ctime = ITIME(now);
                 return ret;
         }