[124/244] restore pinning the victim dentry in vfs_rmdir()/vfs_rename_dir()

[Greg KH]

3.0-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 1d2ef5901483004d74947bbf78d5146c24038fe7 upstream.

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@xxxxxxxxxxxxxxxxxx>
Tested-by: Simon Kirby <sim@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 fs/namei.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2582,6 +2582,7 @@ int vfs_rmdir(struct inode *dir, struct
 	if (!dir->i_op->rmdir)
 		return -EPERM;
 
+	dget(dentry);
 	mutex_lock(&dentry->d_inode->i_mutex);
 
 	error = -EBUSY;
@@ -2602,6 +2603,7 @@ int vfs_rmdir(struct inode *dir, struct
 
 out:
 	mutex_unlock(&dentry->d_inode->i_mutex);
+	dput(dentry);
 	if (!error)
 		d_delete(dentry);
 	return error;
@@ -3005,6 +3007,7 @@ static int vfs_rename_dir(struct inode *
 	if (error)
 		return error;
 
+	dget(new_dentry);
 	if (target)
 		mutex_lock(&target->i_mutex);
 
@@ -3025,6 +3028,7 @@ static int vfs_rename_dir(struct inode *
 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);


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