restore pinning the victim dentry in vfs_rmdir()/vfs_rename_dir()

We used to get the victim pinned by dentry_unhash() prior to commit
64252c75a219 ("vfs: remove dget() from dentry_unhash()") and ->rmdir()
and ->rename() instances relied on that; most of them don't care, but
ones that used d_delete() themselves do.  As the result, we are getting
rmdir() oopses on NFS now.

Just grab the reference before locking the victim and drop it explicitly
after unlocking, same as vfs_rename_other() does.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Simon Kirby <sim@hostway.ca>
Cc: stable@kernel.org (3.0.x)
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/namei.c b/fs/namei.c
index b52bc685465f..f4788365ea22 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2616,6 +2616,7 @@ int vfs_rmdir(struct inode *dir, struct dentry *dentry)
         if (!dir->i_op->rmdir)
                 return -EPERM;
 
+        dget(dentry);
         mutex_lock(&dentry->d_inode->i_mutex);
 
         error = -EBUSY;
@@ -2636,6 +2637,7 @@ int vfs_rmdir(struct inode *dir, struct dentry *dentry)
 
 out:
         mutex_unlock(&dentry->d_inode->i_mutex);
+        dput(dentry);
         if (!error)
                 d_delete(dentry);
         return error;
@@ -3025,6 +3027,7 @@ static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
         if (error)
                 return error;
 
+        dget(new_dentry);
         if (target)
                 mutex_lock(&target->i_mutex);
 
@@ -3045,6 +3048,7 @@ static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
 out:
         if (target)
                 mutex_unlock(&target->i_mutex);
+        dput(new_dentry);
         if (!error)
                 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
                         d_move(old_dentry,new_dentry);